Geological and isotopic evidence for magmatic-hydrothermal

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Geology, C–H–O–S–Pb isotope systematics and geochronology of the Yindongpo gold

Geology,C –H –O –S –Pb isotope systematics and geochronology of the Yindongpo gold deposit,Tongbai Mountains,central China:Implication for ore genesisJing Zhang a ,Yan-Jing Chen b ,c ,⁎,Franco Pirajno d ,Jun Deng a ,Hua-Yong Chen c ,e ,Chang-Ming Wang aaState Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China bKey Laboratory of Orogen and Crust Evolution,Peking University,Beijing 100871,China cKey Laboratory for Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China dCentre for Exploration Targeting,School of Earth and Environment,University of Western Australia,35Stirling Highway,Crawley WA 6008,Australia eCODES ARC Center of Excellence in Ore Deposits,University of Tasmania,7001,Australiaa b s t r a c ta r t i c l e i n f o Article history:Received 19September 2012Received in revised form 10January 2013Accepted 13January 2013Available online 11February 2013Keywords:GeologyIsotope geochemistry Ore genesisYindongpo gold deposit Tongbai MountainsThe Yindongpo gold deposit is located in the Weishancheng Au –Ag-dominated polymetallic ore belt in Tongbai Mountains,central China.The ore bodies are stratabound within carbonaceous quartz –sericite schists of the Neoproterozoic Waitoushan Group.The ore-forming process can be divided into three stages,represented by early barren quartz veins,middle polymetallic sul ﬁde veinlets and late quartz –carbonate stockworks,with most ore minerals,such as pyrite,galena,native gold and electrum being formed in the middle stage.The average δ18O water values changed from 9.7‰in the early stage,through 4.9‰in the middle stage,to −5.9‰in the late stage,with the δD values ranging between −65‰and −84‰.The δ13C CO 2values of ore ﬂuids are between −3.7‰and +6.7‰,with an average of 1.1‰.The H –O –C isotope systematics indi-cate that the ore ﬂuids forming the Yindongpo gold deposit were probably initially sourced from a process of metamorphic devolatilization,and with time gradually mixed with meteoric water.The δ34S values range from −0.3‰to +5.2‰,with peaks ranging from +1‰to +4‰.Fourteen sul ﬁde samples yield 206Pb/204Pb values of 16.990–17.216,207Pb/204Pb of 15.419–15.612and 208Pb/204Pb of 38.251–38.861.Both S and Pb isotope ratios are similar to those of the main lithologies of the Waitoushan Group,but differ from other lithologic units and granitic batholiths in the Tongbai area,which suggest that the ore metals and ﬂuids originated from the Waitoushan Group.The available K –Ar and 40Ar/39Ar ages indicate that the ore-forming process mainly took place in the period of 176–140Ma,during the transition from collisional compression to extension and after the closure of the oceanic seaway in the Qinling Orogen.The Yindongpo gold deposit is interpreted as a stratabound orogenic-style gold system formed during the transition phase from collisional compression to extension.The ore metals in the Waitoushan Group were extracted,transported and then accumulated in the carbona-ceous sericite schist layer.The carbonaceous sericite schist layer,especially at the junction of collapsed anti-cline axis and fault structures,became the most favorable locus for the ore bodies.©2013Elsevier B.V.All rights reserved.1.IntroductionThe concept of orogenic-type gold deposit was ﬁrst introduced by Bohlke (1982)and then thoroughly addressed by Groves et al.(1998),Kerrich et al.(2000)and Goldfarb et al.(2001)to de ﬁne a class of structurally controlled gold deposits formed by ﬂuids,assumed to have originated mainly from syn-to post-orogenic metamorphic devolatilization.Several structurally-controlled lode gold deposits in China and elsewhere have been assigned to the class of orogenic gold de-posits (Chen et al.,2000a,2000b,2001,2012a,2012b;Chen et al.,2005a,2008;Crispini et al.,2011;Fan et al.,2003;Hart et al.,2002;Jiang et al.,2009a,2009b;Kerrich et al.,2000;Mao et al.,2002;Rui et al.,2002;Zhao et al.,2011;Zhou et al.,2002)and interpreted to have mainly formed during continental collision tectonics.Consequently,a tectonic model for collisional orogeny,metallogeny and ﬂuid ﬂow (CMF model)was established to interpret the metallogenic mechanism and space –time patterns of various genetic types including orogenic gold lodes (Chen and Fu,1992;Chen et al.,2004;Pirajno,2009,2012).Many structurally-controlled Ag±Pb –Zn,Pb –Zn±Ag,Cu and Mo lodes have also been interpreted as orogenic type (Chen,2006),including the Tieluping and Yindonggou Ag deposits in Henan province (Chen et al.,2004,2005b;Sui et al.,2000;Zhang et al.,2009);the Gaojiabaozi Ag de-posit in Liaoning province (Wang et al.,2008;Yu et al.,2009);the Tiemurt Pb –Zn –Cu (Zhang et al.,2012),the Wulasigou Cu (Zheng et al.,2012)and Mengku Fe (Wan et al.,2012)deposits in Xinjiang;the Lengshuibeigou,Xigou and Wangpingxigou Pb –Zn±Ag deposits inOre Geology Reviews 53(2013)343–356⁎Corresponding author at:Key Laboratory of Orogen and Crust Evolution,Peking University,Beijing 100871,China.E-mail address:yjchen@ (Y.-J.Chen).0169-1368/$–see front matter ©2013Elsevier B.V.All rights reserved./10.1016/j.oregeorev.2013.01.017Contents lists available at SciVerse ScienceDirectOre Geology Reviewsj ou r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /o r e g e or e vHenan province(Qi et al.,2007,2009;Yao et al.,2008);the Bainaimiao Cu±Au deposit in Inner Mongolia(Li et al.,2008);and the Zhifang Mo (Deng et al.,2008),the Dahu Mo–Au(Li et al.,2011a;Ni et al.,2008, 2012)and the Longmendian Mo(Li et al.,2011b)deposits in Henan province.Recent advances have not only improved the understanding of ore genesis and exploration targeting in orogenic belts,but also intro-duced several new uncertainties.One of them is whether the orogenic type deposit can occur as stratabound style;if not,how to clarify the ge-netic type of deposits formed by metamorphic ore-formingﬂuids that focused in speciﬁc lithologies(e.g.,carbonaceous beds,stratigraphic un-conformities);and if so,what are the geochemical signatures and metal sources of these stratabound orogenic-type deposits.Several gold de-posits,such as Muruntau in Uzbekistan,Kumtor in Kyrgyzstan,Sukhoi Log in Russia,Homestake in USA(Bierlein and Maher,2001;Goldfarb et al.,2001)and Sawayardun in Xinjiang(Chen et al.,2012a,b;Liu et al.,2007),Yangshan in Gansu(Yang et al.,2006,2009)and Yindongpo in Henan(Chen,1995;Zhou et al.,2002),show stratabound characteris-tics but alsoﬁt an orogenic-style of mineral system.In this contribution we report the results of studies on the Yindongpo gold deposit,which occurs in the Weishancheng ore belt in Tongbai Mountains,Henan province,central China(Zhang et al., 2011).The Yindongpo deposit contains32,337kg Au at an average grade of7.61g/t,130.5t Ag at an average grade of38.41g/t, and26,792t Pb at an average grade of0.95%(Zhang Guan,pers. comm.).The deposit is characterized by a stratabound to stratiform ge-ometry,and has attracted the interest of geologists for its metallogenic style,ore genesis,spatial distribution and economic potential(Chen and Fu,1992;HBGMR,1985;Hu et al.,1988;Luo,1992;Xu et al.,1995; Zhang et al.,2009).However,an integrated study on the deposit has not been reported as yet.This paper summarizes the geology and H–O–C–S stable and radiogenic isotopic systematics of the Yindongpo gold deposit,and discusses the sources of ore metals andﬂuids,as well as the ore-forming mechanism(s).2.Geological setting2.1.Regional geologyThe Tongbai Mountains are part of the Central China Orogen (Fig.1A)that was formed during the Mesozoic collision between the Yangtze and North China continents(Wu and Zheng,2012),with the Shang-Dan fault zone being interpreted as main suture(Fig.1B).The Shang-Dan suture zone comprises ophiolite slices and Paleozoic–Triassic sediments,the latter containing radiolarian fossils(Du et al., 1997;Feng et al.,1994).North of the Shang-Dan suture is the northern Qinling accretionary belt(Chen et al.,2009)that includes the Qinling Metamorphic Complex,the Erlangping and Kuanping terranes.These terranes are south of the Luanchuan fault,which is accepted as the boundary between the Qinling Orogen and the reactivated southern margin of the North China Craton(Fig.1B).The Qinling Metamorphic Complex comprises the Qinling Group(pre-Rodinian metamorphic basement)and Neoproterozoic to Paleozoic granitoids which were mostly formed in magmatic-arc settings.The Erlangping terrane, which hosts the Weishancheng ore belt,is bound by the Zhu-Xia fault to south and the Waxuezi fault to north(Fig.1B,C),and mainly com-prises Neoproterozoic–Early Paleozoic volcano-sedimentary succes-sions and associated intrusions that formed in a back-arc basin(Chen et al.,2004;Hu et al.,1988;Sun et al.,2002).In the Kuanping terrane, the Kuanping Group mainly consists of Mesoproterozoic muscovite–biotite(quartz)schists,metagabbros,basaltic rocks and ophiolite slices, and is interpreted as a Mesoproterozoic ophiolite complex accreted to the southern margin of North China Craton(Gao et al.,1991;He etal.,Fig.1.Schematic map showing the geology of the Tongbai Mountains(Zhang et al.,2011).A)Location of the Qinling–Tongbai–Dabie Mountains.B)Tectonic framework of the Qinling–Tongbai–Dabie Mountains.C)Geology of the Tongbai Mountains and the location of the Yindongpo gold deposit.SDF,Shang-Dan suture zone;MLF,Mian-Lue suture zone.SBF,San-Bao fault;F1,Machaoying fault;F2,Luanchuan fault;F3,Waxuezi fault;F4,Zhu-Xia fault;F5,Tong-Shang fault;F6,Tan-Lu fault;F7,Duanzhuang(Duanzhuang–Duimenchong)fault.344J.Zhang et al./Ore Geology Reviews53(2013)343–3562009;Hu et al.,1988;Luo,1992;Zhao et al.,2004,2009).The Kuanping Group is locally covered by or interleaved with Neoproterozoic to Early Paleozoic metamorphic sediments,and thereby is interpreted to have developed in Neoproterozoic or Early Paleozoic(Chen et al.,2009;and reference therein).The Weishancheng Au–Ag-dominated polymetallic ore belt in the northern Tongbai Mountains,strikes WNW for about20km with a width of ca.1km,and is located in the Erlangping terrane,north of the Zhu-Xia fault(F4in Fig.1C).Its eastern and western extensions are covered by Wucheng and Nanyang Cenozoic basins,respectively. The ore belt contains the Yindongpo Au deposit,the Poshan Ag deposit and the Yindongling Ag-dominated polymetallic deposit,as well as nu-merous small ore deposits or occurrences(Figs.1and2).2.2.Local geologyAll the deposits and occurrences in the Weishancheng ore belt are hosted in low-grade metamorphic carbonaceous rocks of the Waitoushan Group(Figs.1and2),which has a total thickness of about2500m and consists of mica schist,quartz–mica schist,plagioclase–amphibole schist, marble and minor quartzite.The Waitoushan Group is divided into the Upper Waitoushan,Mid-dle Waitoushan and Lower Waitoushan Formations(abbreviated as UWF,MWF and LWF respectively in the following text andﬁgures), each containing several members(Fig.3).The UWF is mainly composed of quartz–mica schist.The MWF comprises plagioclase–amphibole schist and carbonaceous quartz–sericite schist.The LWF contains more plagioclase–amphibole schist and marble.In the Tongbai Mountains,the Waitoushan Group is unique for its high abundance of organic carbon,Au,Ag and other metallic elements(Chen and Fu, 1992;HBGMR,1994).The Yindongpo gold deposit is hosted in the sec-ond member of MWF(Fig.3).The axis of the Heqianzhuang anticline strikes90°–120°,and is subparallel with the regional faults(Fig.2).This anticline comprises the Waitoushan Group and Dalishu Formation of the Erlangping Group.The anticlinal axis dies to the east and the hinge plunges towards the west.The Waitoushan Group occurs along the axis of the anticline,whereas the Dalishu Formation forms its southern limb.The orebodies are mainly sited in the hinge and/or along the two limbs of the anticline(Figs.2B,4,5A,C).The NW-trending faults are the dominant regional structures,and are crosscut by the ENE-trending,post-ore faults(Fig.2A).The largest fault is labeled F1and controls the Yindongpo deposit(Fig.2B).The anticline was intruded by granitic plutons,such as the Taoyuan Paleozoic granodiorite pluton and Liangwan monzogranite pluton.The Taoyuan granodiorite yields biotite K–Ar ages of390–357Ma,with the magma being sourced from the basement of northern Qinling accre-tionary belt(Zhang et al.,1999,2000).It intruded the Erlangping Group and Early Paleozoic quartz diorite then was intruded by granites,such as the Liangwan pluton,of Mesozoic age(Yanshanian;see below) (Figs.1and2).The Liangwan monzogranite pluton intruded the Dalishu Formation of the Erlangping Group(Figs.1and2)at128–111Ma(bio-tite K–Ar,whole rock Rb–Sr isochrones)and originated from partial melting of the Tongbai complex in southern Qinling terrane,implying that the lower crust of northern Tongbai Mountains(corresponding to northern Qinling accretionary belt)contains the components fromtheFig.2.Schematic map showing regional and ore geology of the Yindongpo Au deposit.A)Geology of the Weishancheng ore belt after Zhang et al.(2011).B)Geology and distribution of the Yindongpo orebodies,modiﬁed after HBGMR(1994).Abbreviations:XLZ,Xialaozhuang;GLZ,Guolaozhuang;ZZ,Zhangzhuang;LJC,Luanjiachong;JZ,Jiangzhuang;WG,Weigou;NXG, Nanxiaogou;ZhZ,Zhuzhuang.345J.Zhang et al./Ore Geology Reviews53(2013)343–356southern Qinling terrane,via a northward-directed continental subducting slab (Zhang et al.,1999,2000,2011).3.Deposit geology3.1.Characteristics of the orebodiesThe Yindongpo gold deposit covers an area 2km long and 0.6–0.9km wide (Fig.2B).The distribution of the orebodies is strictly con-trolled by carbonaceous beds (graphite-rich quartz –sericite schists)and the Heqianzhuang anticline and fault systems (Figs.2and 4A).The orebodies are typically stratabound and lenticular in shape,or occur as saddles and veins,and generally dip with the hosting strata (Fig.2B).The orebodies in the northern limb of the anticline are steeper than those in the southern limb (Fig.2B).The contacts between orebodies and wallrocks are gradational and are determined by a cut-off grade.The depth of orebodies increases from southeast to northwest.Most of orebodies are hosted in the second member of MWF (Figs.2B,3and 4),especially in the silici ﬁed quartz –sericite schist and/or carbonaceous quartz –sericite schist.The No.0exploration line divides the Yingdongpo deposit into east-ern and western sectors.The eastern sector contains 19ore bodies,with Nos.1,2,3and 3–1being thick,long and continuously mineralized (Figs.2B and 4).In the western ore sector,Nos.51,52,54and 55are the most important orebodies,but are thinner,smaller and less contin-uously mineralized than those in the eastern sector (Figs.2B and 4).The No.1orebody is the largest,with Au reserves accounting for 78%of the ore in eastern sector (HBGMR,1994).It is 1600m long,600m deep and 8m wide,with average grades of 6.23g/t Au and 50g/t Ag,respectively.The ores were mined by open pitting and underground operation.3.2.Ore types and ore mineral assemblagesAltered tectonite breccia,ﬁne vein-disseminated silici ﬁed schist,and silici ﬁed (carbonaceous)quartz –sericite schist (Fig.5),are all Au,Ag,Fe,Cu,Sb,As,Bi,Pb,Zn,Co and Sn enriched,but only Au attained suf ﬁcient ore grades to be economically extracted.Ore minerals include sul ﬁdes,native elements,sulfates and oxides (Fig.5),such as pyrite,chalcopy-rite,sphalerite,galena,native gold,electrum and argentite,and ac-counting for up to 10%of the ore by volume.Gangue minerals are mainly quartz,sericite and carbonate.Fine-grained graphite is com-monly present in the ores (Fig.5D).Cataclastic textures and ﬁssure-ﬁllings are commonly observed.Stockworks,veinlets,disseminations,and banded ores are the main ore styles (Fig.5).3.3.Mineralization stages and wallrock alterationOn the basis of the paragenetic sequences of minerals (Fig.6),ore petrography and crosscutting relationships,the ore-forming process can be divided into three stages,namely,an early-stage barren quartz veins or replacement with or without pyrite (Fig.5F),a middlestageFig.3.Lithostratigraphy and ore metal concentrations of the Waitoushan Group.From HBGMR (1994).346J.Zhang et al./Ore Geology Reviews 53(2013)343–356with polymetallic sul ﬁdes (Fig.5G,H),and a late stage of quartz –carbonate veinlets (Fig.5I).Abundant pyrite,galena,native gold,electrum and other ore minerals formed in the middle stage.Three stage ﬂuid –rock interactions resulted in wallrock alteration,mainly including silici ﬁcation,sericitization,carbonation and chloritization.Silici ﬁcation is the most prominent and in the early stage it was pervasive.Locally,the wallrocks were completely re-placed by ﬁne-grained quartz with minor sericite,forming sericite-bearing siliceous replacement and/or quartz veins.In this case,the primary fabrics of wallrocks,such as schistosity and cleavage,cannot be observed because they were obliterated by pervasive silici ﬁcation.In general,ore grades increase with increasing intensity of hydrother-mal alteration.4.Samples and analytical methodsMost samples in this study were collected from No.1orebody at Levels of 155,145,115and 75(the digits represent the meters above the sea level).Sampling was carried out taking into account the ﬁeld recognition of lateral zonation and the three-stage evolution of the mineralization.Rock samples collected from different strata were pulverized in an agate mill under 200meshes.Mineral aggregates were taken from the specimens using tweezers and then were crushed into grains with sizes of 0.1–0.5mm.After panning and ﬁltration,clean mineral grains (quartz,calcite,and sul-ﬁdes)were handpicked under the binocular microscope.In order to eliminate other interlocking minerals (e.g.sul ﬁdes),quartz separates were soaked in HNO 3-solution at a temperature between 60and 80°C for 12h and rinsed with deionized water.Then the separates were treated 6times using supersonic centrifugal clari ﬁer and rinsed with deionized water for a week.The last rinsed water was monitored by an atomic absorption spectrophotometer to con ﬁrm that no ions were left.The samples were dried in an oven before analysis.For sul ﬁdes,approximately 10to 50mg were ﬁrst leached in acetone to remove surface contamination and then washed by distilled water and dried at 60°C in the oven.The carbonate separates were only washed by distilled water and dried at 60°C in the oven.The analytical methods were explained in detail by Ding (1988).The carbon isotopic composition of ﬂuid inclusion was measured on CO 2.Separated from ﬂuid inclusions in quartz and calcite during thermal decrepitation,the CO 2gas was collected and condensed using a liquid nitrogen-alcohol cooling trap (−70°C)for analysis on a MAT-252mass spectrometry.Hydrogen isotope analysis of water contained in ﬂuid in-clusions was collected in a similar manner.After collection the water was puri ﬁed and then reduced using zinc to produce hydrogen which was analyzed on a MAT-253mass spectrograph.To measure oxygen iso-tope ratios,quartz separates were reacted with BrF 5at 500–550°C for at least 5h to generate O 2which was condensed using liquid nitrogen.The collected O 2was converted to CO 2at about 700°C with platinum as cat-alyzer,and then the CO 2was analyzed on MAT-252mass spectrometry.Sulfur isotope ratios in sul ﬁdes were analyzed on SO 2using Delta-S mass spectrometer.For lead isotope ratios,approximately 10to 50mg of sul ﬁde samples was ﬁrst leached in acetone to remove surface contamination and then washed by distilled water and dried at 60°C in the oven.Washed sul ﬁdes were dissolved in dilute mix solution of nitric acid and hydro ﬂuoric acid.Following ion exchange chemistry,the lead in the solution was loaded onto rhenium ﬁlaments using a phosphoric acid –silica gel emitter.The lead isotopic compositions were measured on MAT-261thermal ioniza-tion mass spectrometer with the standard sample NBS 981.The H –O –C isotopes were measured in the State Key Laboratory of Lithosphere Evolution,Institute of Geology and Geophysics,Chinese Academy of Science.Isotopic data were reported in per mil relative to the Vienna SMOW standard for oxygen and hydrogen,and the Peedee Belemnite limestone (PDB)standard for carbon.Both sulfur and lead isotope analyses were ﬁnished at the Open Laboratory of Iso-topic Geochemistry,Chinese Academy of Geological Sciences.The Sul-fur isotopic compositions were reported relative to the Canyon Diablo Triolite (CDT)standard.Total uncertainties were estimated to be bet-ter than ±0.2‰for δ18O,±2.0‰for δD,±0.2‰for δ13C,and ±0.2‰for δ34S at the σlevel respectively.Estimated precision for the 206Pb/204Pb,207Pb/204Pb and 208Pb/204Pb ratios is about 0.1%,0.09%and 0.30%at the 2σlevel respectively.The K –Ar isochron age was analyzed by RGA-10dating system in Key Laboratory of Orogen and Crust Evolution,PekingUniversityFig.4.Simpli ﬁed exploration sections showing orebodies of the Yindongpo Au deposit.Modi ﬁed after HBGMR (1994).347J.Zhang et al./Ore Geology Reviews 53(2013)343–356and the systematic error of K –Ar dating is estimated to be b 4%.The 40Ar/39Ar plateau age was analyzed at the Geochronology Research Laboratory of Queen's University,Ontario,Canada.40Ar/39Ar analyses were performed by standard laser step-heating techniques described in detail by Clark et al.(1998).All data have been corrected for blanks,mass discrimination,and neutron-induced interferences.A plateau age is obtained when the apparent ages of at least three consecutive steps,comprising a minimum of 55%of the 39Ar k released,agreeFig.5.Geology,ore type and mineral assemblages of the Yindongpo gold deposit.A)Heqianzhuang anticline axis shown at an open pit;B)ore-hosting fault developed along the boundary between carbonaceous schist and two-mica schist;C)north limb of the No.55orebody (30°∠60°)and its foot-and hanging-walls;D)a small-size anticline in altered carbonaceous quartz schist;E)pyrite-bearing quartz veinlets in carbonaceous quartz schist;F)early-stage barren,milky quartz vein;G)pyrite-rich,high-grade ore;H)middle-stage ore rich in pyrite and galena;I)late-stage quartz-carbonate vein;J)chalcopyrite armored with covellite;K)euhedral pyrite in quartz;L.pyrite with cataclastic texture;M)sphalerite with thin ﬁlm of tiny galena;N)sphalerite containing chalcopyrite droplets,forming exsolution texture;O)early-stage pyrite replaced by galena.348J.Zhang et al./Ore Geology Reviews 53(2013)343–356within 2σerror with the integrated age of the plateau segment.Errors and isotope-correlation diagrams represent the analytical precision at ±2σ.5.Isotope systematics 5.1.Hydrogen –oxygen isotopesThe δD and δ18O values for the Yindongpo ore deposit are listed in Table 1.The δ18O water was calculated according to the δ18O mineral and trapping temperature of ﬂuid inclusion which was estimated according to homogenization temperature and its pressure correlation.The ﬂuids of early-stage quartz (sample 99H09)have an δ18O water value of about +10.6‰,higher than the maximum for magmatic water,suggesting that the ﬂuids were sourced from metamor-phic devolatilization rather than magmatism (Chen et al.,2005b,2008).It is common knowledge that magmatic ﬂuids are generated from the magma above the temperature of 573°C (lowest eutectic point).The δ18O water ratio of the initial magmatic ﬂuids is not higher than the δ18O quartz of the equilibrated magmatic rocks,due to 1000ln αquartz –water >0when T b 724°C.Hence the maximum δ18O water value of magmatic water was estimated to be 9‰(Fig.7).During continuous cooling and water –rock reaction processes,the δ18O water of magmatic water was reduced again along with the formation of hy-drothermal minerals such as quartz.If the ﬂuids forming the Yindongpo deposit were initially magmatic and still kept δ18O water =+10.6‰when the temperature decreased to 414°C,their initial δ18O water must be far higher than 10.6‰.Such δ18O water value is obviously higher than the estimated maximum for magmatic water,also higher than the δ18O values of granitoids in Qinling –Tongbai Mountains,which range 6.1‰–10.4‰(Chen et al.,2000b ).Thus,the early stage ﬂuid must be metamorphic in origin,instead of magmatic or meteoric,which is further supported by sulfur and lead isotope signatures,discussed ahead.The δ18O values of the middle-stage ﬂuids range from +3.1‰to +5.5‰,averaging +4.9‰;whereas the δD values range from −68‰to −84‰,and average −75‰.Compared to the early-stage ﬂuids,sam-ples of the middle-stage ﬂuids clearly shift towards the meteoric water line (Fig.7),suggesting a signi ﬁcant input of meteoric water into the ﬂuid system.The δ18O water values of late-stage quartz and calcite are between −8.1‰and −3.7‰,averaging −5.9‰.Such low δ18O water values strong-ly indicate that the ﬂuids were mainly sourced from meteoric water.Con-sidering the δD ratios in ﬂuids vary in a narrow range (−65to −85‰)in early and middle stages,we estimate that the late stage δD water values are similar to the middle stage.These measured and estimated δD water values are close to that of Mesozoic meteoric water in Qinling Moun-tains (Fig.7).Assuming that the average δD water value of the late stage is same to that of the middle stage,the late stage samples are close to or shift towards the meteoric water line,especially to the domain of Mesozoic meteoric water in Qinling mountain range (Fig.7),which was drawn by Zhang (1989)from a H –O isotope geochemical study of numerous meteoric hydrothermal deposits formed in Mesozoic.This suggests that the late stage ﬂuids are of meteoric origin.In conclusion,the average δ18O Water values changed from 9.7‰in the early stage,through 4.9‰in the middle stage and −5.9‰in the late stage,with the δD values ranging between −60‰and −90‰,strongly support that the ore ﬂuids of the Yindongpo gold deposit were initially sourced from metamorphic devolatilization,and later changed to mainly meteoric water,from the early to the late stages of the mineralization process.5.2.Carbon isotopesThe δ13C CO 2values of the early-and middle-stage ﬂuids forming the Yindongpo Au deposit widely vary between −3.7‰and +6.7‰,with an average of 1.1‰(Table 1).These values are higher than those of organic matter (ca.−27‰),atmospheric CO 2(−7to −11‰;Hoefs,2004),freshwater carbonate (−9to −20‰:Hoefs,2004),igneous rocks (−3to −30‰:Hoefs,2004;Zheng,1999),continental crust (−7‰:Faure,1986)and the mantle (−5to −7‰:Hoefs,2004);and therefore,the CO 2in the ﬂuids forming the Yindongpo mineral system cannot independently have been supplied by any one or a mixture of the above-mentioned reservoirs.The marine carbonate,which is the carbon reservoir with highest δ13C value (ca.0.5‰;Schidlowski,1998),must be considered as the source of CO 2in the ore ﬂuids,at least as a necessary end-member,considering that released CO 2via decarbonation could have higher δ13C than the residue carbonates (Jiang et al.,2004;Tang et al.,2011,in press ).The δ13C values of the carbonates in Waitoushan Group range from +1.9‰to +2.9‰(Table 1),suggesting that they most likely provided CO 2(with the highest δ13C value of 6.7‰)for the Yindongpo ore ﬂuid-system via metamorphic de-carbonation.The δ13C values of calcite in late-stage veins at Yindongpo deposit range from −2.4‰to −0.6‰(Table 1),and correspond to the δ13C CO 2values of −2.8‰to −1.0‰calculated using the carbon isotope fractionation equation of for calcite –CO 2system (Chacko et al.,1991).The calculated δ13C CO 2values are lower than the δ13C CO 2values of ore-forming ﬂuids in early and middle stages,suggesting that the ﬂuid system was mixed with or replaced by meteoric water,which ef ﬁciently reduced the δ13Cvalue.Fig.6.Paragenetic sequence for major minerals of the Yindongpo Au deposit.349J.Zhang et al./Ore Geology Reviews 53(2013)343–356。

ICP-MS分析

ICP-MS分析1000-0569/2007/023(02)43227—32ActaPetrologicaSinica岩石地质样品的一次阴离子色谱法Hf分离及其MC—ICP-MS分析杨岳衡张宏福刘颖谢烈文祁昌实,Y ANGYueHeng一,ZHANGH0ngFu,LIUYing3XIELieWen,Qt涂湘林ChangShi?andTUXiangLin1.中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京1000292.中国科学院广州地球化学研究所同位素年代学和地球化学重点实验室,广州5106403.中国科学院研究生院,北京1000391.StateKeyLaboratoryofLithosphericEvolution,lttstitttteofGeologyandGeophysics,Chi neseAcademyofScie~es,Beijing100029,China2.KeyLaboratoryofhompeGeochronologyandGeochemistry,GuangzhouInstituteofGeo chemistry,ChineseAcademyofSciences,Guangzhou510640,China3.GraduateSchooloftheChineseAcademyofSciences,Beijing100039,China2006-09—30收稿.2006—12-25改回.Y angYH,ZhangHF,LiuY,XieLW,QiCSandTuXL.2007. samplesusinganionexchangechromatographyanditsisotopic23(2):227—232OnecolumnprocedureforHfpurificationingeologicalanalysesbyMe-ICP-MS.ActaPetrologicaSinica,AbstractAone—columnprocedureforHfpurificationingeologicalsamplesusinganionexchangechromatog raphyanditsisotopicanalysesbyMC—ICP—MSwasdevelopedinthispaper.ThechemicalseparationbetweenHfandisobaricelementssu chasLu,Yband matrixmaterialslikeTiWascarriedoutsimultaneouslythroughpopularanionexchangechro matography.Thistechniqueavoidsusing popularmultipleionexchangechromatography,specialextractionchromatographicresinsa ndperchloricacidtobreakdownHfand REEfluoridesafterHFdissolvedtherock.Hfyieldsare>90%andtotalproceduralblanksa reca.50pg.Muhipleanalysesof StandardReferenceMaterialsdemonstratethatthismethodwassimple,time—saving,inexpensiveandefficient,especiallysuitablefor theHfisotopiccompositionofyoungsamples.KeywordsHfisotope,MC—ICP—MS,Anionexchangechromatography,Geologicalsamples摘要本文建立了适合MC—ICP—MS测试地质样品中Hf同位素的一次阴离子交换化学分离方法.使用常规的阴离子交换树脂就可以完成Hf与干扰元素和基体元素的分离,避免了当前广泛采用的多次离子交换柱的麻烦,也无需使用特效树脂,HF处理样品后,也不必使用HC10赶尽HF.Hf的回收率大于90%,过程空白约为50pg.岩石标样的重复分析表明,该方法简单,快速,经济,有效,尤其适合年轻地质样品Hf同位素组成分析.关键词Hf同位素;MC—ICP—MS;阴离子交换色谱法;地质样品中图法分类号P588.122近十年来,多接收器电感耦合等离子体质谱(Multi—CollectorInductivelyCoupledPlasmaMassSpectrometry:MC—ICP—MS)的出现,使得高电离能元素Hf的同位素测试变得简便和快捷,不但样品的化学分离大大简化,而且质谱测试速度也大大加快.国际核心刊物有关Hf同位素分析方法及其应用研究成果不断涌现(Blichert—Toft,2001).在这一国际Hf同位素热潮下,国内Hf同位素研究也取得了可喜的进展.李献华等(2003)首次进行了锆石的激光取样(Laser本文受国家自然科学基金委大陆动力学重点项目(40534022),国家杰出青年科学基金项目(40225009)和中国科学院广州地球化学研究所所长测试基金联合资助.第一作者简介:杨岳衡,男,1970年生,在职博士生,同位素地球化学专业,E-mail:***********************228Ablation:LA)MC—ICP—MS测试Hf同位素研究,随后徐平等(2004)也开展了系列标准锆石Hf同位素工作.短短几年时间,国内学者的努力使得锆石LA—MC—ICP—MS的Hf同位素测试技术13趋成熟,并得到了国际同行认可(wueta1.,2006),为我国学者运用该技术研究国内地质问题提供了条件,相应地,也取得了可喜的研究成果(1Jela1.,2005a;Y angeta1.,2005;Zhengeta1.,2005;Jiangeta1.,2006;Lieta1.,2006;Wueta1.,2006;Xiaeta1.,2006;Y angeta1.,2006a;2006b;Zhangeta1.,2006a;2006b).同时,国内多家实验室也先后建立了岩石样品(Yuaneta1.,2004;李献华等,2005b;韩宝福等,2006)的Hf分离方法.总体而言,目前岩石样品的Hf分离方法不是采用多次阴,阳离子交换(Blichert.Torteta1.,1997;Davideta1.,1999;Amelineta1.,1999;LeFevreandPin2001;Kleinhannseta1.,2002;Bizzarroeta1.,2003;LeFevreandPin2005;韩宝福等,2006;Lueta1.,2007)就是使用特效树脂(如Ln,UTEV A,TODGA树脂)(Munkereta1.,2001;Yuaneta1.,2004;李献华等,2005b;Connelly2006;Connellyeta1.,2006;Laeta1.,2007)来实现Hf与干扰元素和基体元素分离.同时,由于Hf极易与F一络合的特性,样品经过HF溶解后,都必须用HC104赶尽HF(PatchettandTatsumoto1980;SaltersandHart1994;Munkereta1.,2001;韩宝福等,2006; Connelly2006;Connellyeta1.,2006;Lueta1.,2007),否则严重影响Hf的回收,或者,避免HF的使用而采用碱熔方法处理样品(LeFevreandPin2001;Bizzarroeta1.,2003;Ubecketa1.,2003;LeFevreandPin2005;李献华等,2005b).本文在前人工作的基础上(Munkereta1.,2001),利用Hf与F一络合在阴离子树脂有较高的分配系数,而干扰元素(Yb,Lu)不在柱上吸附.同时,在不同的酸度体系下又实现基体元素(rri)与Hf的分离,从而一次在阴离子交换柱上实现Hf与其他元素的分离,这样既可以采用HF溶解样品,又无需使用HC10赶尽HF,也避免了特效树脂(如Ln树脂)的有限使用次数的限制(Munkereta1.,2001;Yuaneta1., 2004),降低了成本.岩石标样的重复测试表明,该方法简单,快速,经济,有效.ActaPetrologicaSinica岩石2007,23(2)l样品溶解与化学分离本实验中使用高纯水(电阻率>18MI'I);HC1,HNO,HF是北京化工厂优级纯试剂经过二次亚沸蒸馏纯化得到; HAc,H:O和H,BO,为北京化工厂优级纯试剂;标准溶液AlfaHf100001xg/ml(No.14374),AlfaLulO001xg/ml(No. 35765),AlfaYb10001~g/ml(No.13819),AlfaZrlO001xg/ml (No.13875)和AlfaTi1000g/ml(No.35768)购自Johnson MattheyCompany的AlfaAesar公司,逐级稀释为工作溶液;标准溶液Ta(1O001xg/m1)和W(1O001xg/m1)购自国家标准物质研究中心,逐级稀释为工作溶液;树脂为Bio—RadAG1.X8 (200～400mesh,C1一型),装填树脂材料为Bio.Rad2ml(0.8×4cm).称取lOOmg样品,于7mlSavillex溶样罐中,加入2ml浓HF和0.5ml浓HNO,置于电热板上保温一周,期间不时摇动溶样罐,使得样品充分溶解,蒸干样品,加入适量的HBO和HC1,保温l2小时溶解样品,再次蒸干,然后加入6MHC1溶解样品,蒸干,最后加入3MHC1溶解样品,保温l2小时,然后加入少量的水和微量HF,准备上柱.化学分离的详细步骤见表1.2质谱测试Hf同位素分析是在中国科学院地质与地球物理研究所岩石圈演化国家重点实验室ThermalFinniganNeptuneMC—ICP—MS上完成的.有关仪器详细介绍,详细参见文献(wueta1.,2006).Hf同位素组成的测定,全部采用静态方式,具体的法拉第杯结构:L4:"Yb,L3=Lu,L2:蜥Yb+Lu+Hf,Ll=77Hf,Center=78Hf,Hl:79Hf,H2=柏Ta+柏Hf+柏W,H3:Ta,H4=w.测量"Yb是为了监控"Yb对"6Hf的干扰,测量Lu是为了监控Lu对"Hf的干扰,测量…Ta是为了监控Ta对.Hf的干扰,测量w是为了监控.w表1一次阴离子交换柱的Hf分离流程Table1OnecolumnprocedureforHfpurificationusinganionexchangechromatography杨岳衡等:地质样品的一次阴离子色谱法Hf分离及其MC—ICP—MS分析对Hf的干扰.在测试样品之前,使用实验室的内部标准AlfaHf标准溶液(200ng/m1)对Neptune进行参数优化,包括等离子体部分(炬管位置和载气流速等参数)和离子透镜参数,以达到最大灵敏度.通常,200ng/mlAlfaHf的标准溶液,Hf信号强度为3.5V左右.在以后的实际样品测试过程中,只是对炬管位置和载气流速稍作调节即可进行实际样品的测量.仪器的操作条件参见文献(wueta1.,2006).化学分离后的Hf用2%HNO+0.1%HF溶液引入质谱,使用自由雾化进样方式.样品测量完成后,使用2%HNO+0.1%HF溶液清洗进样系统,然后开始下一个样品的测量.通常,完成一个样品的测量时间为10Min,两个样品之间洗涤时间为5Min.经验表明,2%HNO+0.1%HF混合溶液比单纯2%HNO而言,洗涤Hf具有更好的效果.3结果与讨论3.1结果重复测试岩石标样Hf同位素分析结果列于表2.可以看出,国家岩石标样GSR-3(玄武岩)的表2岩石标样的Hf测试结果Table2ResultsofHfisotopicanalysesforSRM229".Hf/"Hf比值与碱熔后用特效树脂(如Ln树脂)的结果在误差范围内完全一致(李献华等,2005b),其他国际岩石标样BCR一1,BHVO一2,W-2的Hf/"Hf比值与文献报道的值在误差范围内也完全一致(PatchettandTatsumoto1980: Blichert—Toft2001;Davideta1.,2001;LeFevreandPin2001: Munkereta1.,2001;Chueta1.,2002;Bizzarroeta1.,2003; Ubecketa1.,2003;Lapeneta1.,2004:Weieta1.2004:Wittingeta1.2006;李献华等,2005b;韩宝福等,2006).以上测试结果表明,我们所获得的Hf同位素组成是准确可信的,化学分离方法是有效的.3.2讨论Munkereta1.(2001)发展了适合zr同位素MC.ICP—MS分析的单柱阴离子色谱法分离方法.由于zr,Hf极其相似化学行为,同时MC—ICP—MS测试zr,Hf同位素的要求又不尽相同,如Mo,Cr40Ar,W干扰zr,Yb,"6Lu,GdO,DyO干扰Hf,.Ta和啪W干扰.Hf,我们在此基础上发展了适合Hf同位素MC—ICP—MS分析的化学分离方法.(1)硼酸在地质样品分析中,HF作为破坏硅酸盐有效试剂广泛使用,钙和镁作为主量元素在地质样品中则大量存在,尤其对基性和超基性样品而言,大量氟化钙,镁沉淀严重影响Hf的回收(Blichert—Toft,2001;Connellyeta1.,2006),同时,稀土元素也容易形成氟化物沉淀.因此,我们在HF样品溶解后加入适量的硼酸来络合F一,破坏氟化物沉淀,使得钙,镁和稀土元素以阳离子形式存在,大大提高了Hf的回收率,同时,也使得以阳离子形式的稀土元素在阴离子交换树脂上不停留.(2)同质异位素由于同质异位素("Yb,Lu)的存在以及稀土元素氧化物(GdO,DyO)干扰Hf.因此,稀土元素必须彻底与Hf分离.在阴离子交换柱上,稀土元素等阳离子不在阴离子柱上吸附,穿柱而过,而Hf与F结合的络合阴离子则紧紧吸附在树脂上,只有在较高浓度HC1才能够淋洗下来,这就保证了稀土元素与Hf的彻底分离,有效地避免了MC—ICP—MS分析Hf时的同质异位素干扰. 同时,在实际质谱测试过程中,也可以通过"Yb和"Lu的信号强度来监控它们与Hf的分离程度,质谱测试数据显示,"Yb和Lu法拉第杯的信号强度均小于0.00004V,充分说明了它们之间的彻底分离.研究表明,当含Hf溶液中"Yb!Hf和"Lu/Hf的信号强度均小于0.0001时,不必对"Hf/"Hf比值做同质异位素的干扰校正(李献华等,2005b).尽管在阴离子交换柱上Hf与稀土元素能够有效的分离,但为了检验NeptuneMC—ICP—MS对同质异位素的干扰扣除能力,在AlfaHf标准溶液(200ng/ml,下同)中加入不同量的Lu和Yb来进行实验,测试结果表明,在Lu/Hf<0.1,Yb/Hf<0.04时,NeptuneMC—ICP—MS可以完全有效的进行同质异位素的干扰扣除(图1A,B),这也进一步印证了LA—2300.282220.282200.282l8至0.282160.282l40.282l2000002000060001000400080020060l0408 000010000400008000200060010040080206l0Lu/Hf0.2824O0.282350.28230028225028220ActaPetrologicaSinica岩石2007,23(2):l{_000O020*******l000400080020060l040000l00004000080002000600l00400802Yb/Hf图1AlfaHf中加入不同量Lu,Yb对MC—ICP—MS测试Hf的影响Fig.1EffectsofAHfanalyseswithanadditionofvariableLu.Ybcontents 0282230.2822l兰0.28219:.{_lI;i..l}I'}Il{{一.工ll'A00o00200006000l00040008002006010400004000080o0200060,0J00400802lI}}".Ili.一fii00000200006000l00040008002006010400004000080o02000600l0040080206w/Hf图2AlfaHf中加入不同量Ta,w对MC—ICP—MS测试Hf的影响Fig.2EffectsofAlfaHfanalyseswithanadditionofvariableTa,Wcontents MC—ICP—MS进行(斜)锆石Hf同位素分析时"Hf的同质异位素干扰主要来自"Yb.此外,在化学分离中Ta和w与Hf之间的彻底分离则是比较困难的,尽管它们对".Hf没有直接的干扰,但是'册Ta和啪w干扰.Hf,为此,在AlfaHf标准溶液中加入不同量的Ta和w来进行实验,测试结果表明,Ta和w的存在对MC.ICP—MS测试Hf没有影响(图2A,B). (3)基体元素MC.ICP—MS较以前经典的热电离质谱(ThermalIonizationMassSpectrometry:TIMS)或热一二次离子质谱(hotSecondaryIonMassSpectrometry:hot—SIMS)测试Hf最突出的优点是无需zr,Hf分离.由于zr,Hf极其相似的化学性质,几乎相同的离子半径(分别为0.80,0.81h),实现它们之间的分离需要非常繁琐的步骤(Patchettand Tatsumoto1980:SaltersandHart1994),而这恰恰是Hf化学分离的难点,也是以前TIMS和hot—SIMS必须克服的难关(Bliehert.T0fl2001).研究表明,Zr/Hf达到200(祁昌实等,2005)甚至到800(Goolaertseta1.,2004)对Hf同位素的MC—ICP.MS测试没有影响.在NeptuneMC—ICP—MS进行不同zr/H喊验,结果表明,大量zr的存在不影响Hf同位素的测试(图3A),Zr,Hf无需分离,这样化学分离大大简化.同时,MC.ICP—MS对Ti,Hf之间分离也没有TIMS或hot—SIMS要求那么苛刻.尽管Ti的存在对Hf的MC—ICP—MS分析没有质谱干扰,但是大量Ti的存在容易在锥孑L堆积,大大降低了Hf的传输效率,造成电障效应,引起仪器产生质量漂移(Blichert—Toileta1.,1997),因此,绝大部分还是需要与Hf分离.Goolaertseta1.(2004)曾对样品中Ti含量对Hf同位素测定的影响作过研究,在Ti/Hf浓度比值高达30的JMC-475标准溶液中s176Hf/Hf测量结果没有受到明显的影响.研究表明,在醋酸,硝酸和双氧水混合体系中,n与F一的络合离子的分配系数很小(～1),远远小于zr,Hf络合F一的络合离子的分配系数(大于100)(Munkereta1.,2001),因此,在该条件下,可以实现Ti与Hf的有效分离.在实际地质样品中,TiO含量变化较大,一般为0.01—4%,杨岳衡等:地质样品的一次阴离子色谱法Hf分离及其MC—ICP—MS分析0.282220.282200.282l80.282l60282l4Mean:0.282185±0.000013(2SDN=22).TI:…it.I;…IITlT…T:?工工一fl,上t上tt圭王1i士f-t～.AMcan:0.282187±0.000007(2SDN=26)T?TTI-.r.TITTT{IITIITll1T}TII~TTTIIH.Bo1o4o.826lo305070901200l0.40.826103050709012016020000.20.6l4820406080l0000.20.6l4820406080l00l40l80ZHfTi/Hf图3AlfaHf中加入不同量Zr,Ti对MC—ICP—MS测试Hf的影响Fig.3EffectsofAlfaHfanalyseswithanadditionofvariableZr,Ticontents 金红石则达90%以上,我们使用4MHAc+8mMHNO3+1%H,0,混合溶液淋洗,可以看到非常明显的橙黄色溶液,直到变成无色,接下来,用6MHC1+0.1MHF淋洗并接收zr,Hf用于进一步分析.在NeptuneMC—ICP—MS也进行不同Ti/Hf试验(图3B),结果表明,即使Ti/Hf达到200,也没有观察到对Hf的MC—ICP—MS测试有明显的影响.通常化学分离后,Ti/Hf通常小于5,这样不会对Hf分析有影响,从岩石标样的测试结果也间接证明了这一点.4小结建立了一次阴离子交换柱实现Hf与干扰元素和基体元素的化学分离方法.该方法既可以采用HF处理样品,又无需用HCIO赶HF,也避免了使用特效树脂.岩石标样的重复测试表明,该方法简单,快速,经济,有效,尤其适合年轻地质样品Hf同位素组成分析.致谢本文前期实验是在中国科学院广州地球化学研究所同位素年代学与同位素地球化学重点实验室完成的.实验室主任李献华研究员给予悉心的指导和热情帮助.作者与北京大学地球与空间科学学院韩宝福教授和西北大学教育部大陆动力学实验室袁红林博士就相关问题进行了讨论与交流.两位匿名审稿人提出了宝贵的修改意见,进一步完善了论文.在此,一并致以诚挚的谢意.ReferencesBizzarroM,BakerJA,UlfbeckD.2003.ANewDigestionandChemical SeparationTechniqueforRapidandHighlyReproducible DeterminationofLu/HfandHfIsotopeRatiosinGeologicalMaterials byMC—ICP—MS.Geostand.Newslett.,27(2):133—14523lBliched..r0flj.ChauvelC.AlbaredeF.1997.SeparationofHfandLuf0rhigh—precisionisotopeanalysisofrocksamplesbymagnetic sector-multiplecollectorICPMS.Contrib.Minera1.Petro1..127: 248—260Blichert..r0flj.2001.0ntheLu—Hfisotopegeochemistryofsilicate rocks.Geostand.Newslett.,25(1):4l一56ConnellyJN.2006.Improveddissolutionandchemicalseparation methodsforLu—Hfgarnetchronometry.Geochem.Geophys. Geosyst.,7:Q04005,doi:10.1O29/20o5GGoolO82 ConnellyJN,UlfbeckD,ThraneKeta1.2006.PurifyingLuandHff0r analysesbyMC—ICP—MSusingTODGAresin.Chem.Geo1..233: l26一l36DavidK,BirckJL,TeloukPeta1.1999.Applicationofisotopedilution forDrecisemeashrement0fZr/Hfand176H￡/77Hfratiosbymass spectrometry(ID.TIMS/ID—MC—ICP—MS).Chem.Geo1..157:l—l2GoolaertsA,MattielliN,Jongjeta1.2004.HfandLuIsotopic ReferenceV altiesfortheZirconStandard9150obvMC—ICPMS. Chem.Geo1..2o6:l一9HanBF.ZhangL.GuLBeta1.2006.SeparationofHffromrocksamplesforisotopeanalysisbyMC—ICP—MSusingion—exchange chromatographymethod.ActaPetrologicaSinica,22(2):513—516 (inChinesewithEnglishabstract)JiangYH,JiangSY,LingHFeta1.2006.Low—degreemeltingofa metasomatizedlithosphericmantlefortheoriginofCenozoicYulong monzogranite—porphyry.eastTibet:GeochemicalandSrNdPbHf isotopicconstraints.EarthP1anet.Sci.Lett..24l:617—633K1einhannsI.KreissigK,binedchemical separationofLu,Hf,Sm,NdandREEsfromasinglerockdigest: DreciseandaccurateisotopedeterminationsofLu—HfandSm—Nd usingmuhicollector—ICP—MS.Ana1.Chem.74:67—73LeFe,vreB.PinC.2005.Astraightforwardseparationschemeforc0nc0mitantLuHfandSmNdisotoperatioandisotopedilution analysis.AnalyticaChimicaActa.543:209—22lkFe,vreB.PinC.2001.Anextractionchromatographymethodf0rHf separationpriortoisotopicanalysisusingmuhiplecollectionICP—massspectrometry.Ana1.Chem..73:2453—2460LiXH,LiangXR,WeiGJeta1.2003.PreciseanalysisofzirconHfisot0pesbvLAM—MC—ICPMS.Geochimica,32:86—9O(inChinese withEnglishabstract)LiXH,QiCS,LiuY eta1.2005a.PetrogenesisoftheNeopro—temzoic232bimodalvolcanicrocksalongthewesternmar~noftheY angtzeBlock:NewconstraintsfromHfisotopesandFe/Mnratios.Chin.Sci.Bul1..50:248l一2486LiXH,Qics.LiuYeta1.2005b.RapidseparationofHffromrock samplesforisotopeanaIvsisbyMC—ICPMS:amodifiedsingle—colunlll exlractionchromatographymethod.Geochimica,34(2):109一ll4 (inChinesewithEnglishabstract)LiXH,LiZX,WingateMTDeta1.2006.Geochemistrv0fthe755Ma MundineWelldykeswalTfl,northwesternAustralia:Partofa NeoproterozoicmantlesuperplumebeneathRodinia?Preeambrian Res..146:l—l5LuYH.AkioMakishimaandEizoNakamura.2o07.PurifieationofHfin silicatematerialsusingextractionchromatographicresin,andits applicati0ntoprecisedetemilnati0nof76Hf/77HfbvMC—ICP—MS with79Hfspike.J.Ana1.At.Speetrom..22:69—76MtinkerC,WeyerS,SchererE,MezgerK.2001.Separationofhigh fieldstrengthelements(Nb,Ta,zr,Hf)andLufromrocksamples forMC—ICPMSmeasurements.Geochem.Geophys.Geosyst.2.10. 1029/2o0lGCO0o183PatchettP.TatsumotoJ.1980.Aroutinehigh—precisionmethodforLu—Hfisotopegeochemistryandchronology.M.,Contrib.Minera1.Petro1..75:263—267QiCS,LixH,LiangxReta1.2005.High—precisionmeasurementofHf isotopicreferencevaluesfortheU—Pbgeochronologystandardzircons bymulti—collectorICP.MS.JournalofChineseMassSpectrometry Society,26(3):149—154.(inChinesewithEnglishabstract) SaltersVJM.1994.76Hf/Hfdeterminationinsmallsamp1esbva high—temperatureSIMStechnique.Ana1.Chem.,66:4186—4189 UlfbeckD,BakerJA,WaightTeta1.2003.Rapidsampledigestionby fusionandchemicalseparationofHfforisotopicanalysisbyMC..ICP. MS.anta.59:365—373WeisD.KiefferB.MaersehalkCeta1.2o05.High—precisionPb—Sr-Nd—HfisotopiccharaterizationofUSGSBHV0.1andBHVO-2reference materials.Geoehem.Geophys.Geosyst.,2,10.1O29/2oo4GCoo0852WittigN,BakerJAandDownesH.2006.Datingthemantlerootsofyoungcontinentalcrust.Geology,34(4):237—240 WiedenbeckM.AlleP.CorfuFeta1.1995.rhreenaturalzircon standardsforUrhPb.LuHf.traceelement.andREEanalyses. Geostand.Newslett..19:l一23Wu,F.Y.,Y ang,Y.H.,Xie,L.W.,eta1.2o06.Hfisotopic compositionsofthestandardzirconsandbaddeleyitesusedinUPb geochronology.Chem.Geo1.,234:105—126Xia,X.P.,Sun,M.,Zhao,G.C.,eta1.2006.UPbandHfisotopic studyofdetritalzirconsfromtheWulashankhondalites:Constraints ontheevolutionoftheOrdosTerrane.WesternBlockoftheNorth ChinaCraton.EarthPIanet.Sci.Lett..24l:581—593XuP,WuFY.XieLWeta1.2oo4.Hfisotopiccompositionsofthe standardzirconsforU—Phdating.Chin.Sci.Bul1..49:1642一l(珥8Y angJH,WuFY,ChungSLeta1. significanceofEarlyCretaceous uhrabigh—pressureorogenicbelt,2005.Petrogenesisandtectonic graniticmagmastismintheSuluEastChina.Chem.Geo1.,222:ActaPetrologicaSinica岩石2007,23(2)2【x】一23lY angJH,WuFY,ChungSLeta1.2006a.Ahybridoriginforthe QianshanA—typegranites,northeastChina:GeochemicalandSr—Nd—Hfisotopicevidence.Lithos.89:89—106Y angJH.WuFY,ShaoJAeta1.2006b.OntheinitialtimingoftheY anshanMountainbuilding.EarthPlanet.Sei.Lett.,246:145一l6oY angXJ.PinC.2000.Determinationoftracezirconiumandhafniumin basalticrocksbyinductivelycoupledplasmaatomicemission spectrometryafterchemicalseparation:allevaluationoftwomethods basedonextractionchromatography,Analyst,125:453—457 YuanHL.GaoS.UweNeta1.2004.,nmckingthecontinental founderingprocess:evidencefromhafniumisotopiccompositionsby multiplecollectorinductivelycoupledplasmasmass spectrome.p344ZhangJH,GeWC,WuFY.2006a.Mesozoicbimodalsuiteandits geologicalsignificanceinZhalantunoftheGreatXing'anRange: zir?。

陨石撞地球英语作文简单

陨石撞地球英语作文简单Title: A Close Encounter: When a Meteorite Strikes Earth。

Introduction:The universe is an awe-inspiring expanse, filled with celestial bodies ranging from distant stars to wandering asteroids. Occasionally, these cosmic travelers venture too close to home, leading to dramatic events like meteorite impacts on Earth. In this essay, we delve into the phenomenon of meteorite impacts and their implications.What is a Meteorite?A meteorite is a solid piece of debris from an object such as a comet, asteroid, or meteoroid that survives its passage through Earth's atmosphere and lands on theplanet's surface. These fragments can vary in size fromtiny grains to massive boulders weighing several tons. Whenthey collide with Earth, they can cause significant damage depending on their size and velocity.The Impact Process:When a meteorite enters Earth's atmosphere, it encounters resistance from air molecules, causing it to heat up and glow brightly, creating a spectacular sight known as a meteor or shooting star. Most meteoroids burn up completely during this fiery descent, never reaching the surface. However, if the meteorite is large enough and robust, it can withstand the intense heat and pressure, making it through to impact the Earth's surface.Consequences of Impact:The consequences of a meteorite impact can be profound, ranging from localized destruction to global cataclysms. Small meteorites may create impact craters and cause minimal damage, while larger ones can unleash devastation on a much grander scale. Historical records and geological evidence indicate that several mass extinction events inEarth's history, including the demise of the dinosaurs, may have been triggered by massive meteorite impacts.Scientific Importance:Despite the potential for destruction, meteorite impacts also present invaluable scientific opportunities. The study of meteorites provides insights into the composition and evolution of our solar system. By analyzing the chemical and isotopic signatures of meteorites, scientists can unravel the mysteries of planetary formation and early solar system dynamics.Mitigation and Preparedness:Given the potential threat posed by meteorite impacts, scientists and policymakers are actively engaged in efforts to mitigate the risks and enhance preparedness. Advanced telescopes and monitoring systems are deployed to track near-Earth objects (NEOs) and identify potential impact threats well in advance. Additionally, international collaborations facilitate the development of strategies fordeflecting or intercepting incoming asteroids or comets, thus reducing the likelihood of catastrophic impacts.Conclusion:In conclusion, meteorite impacts represent afascinating yet potentially hazardous aspect of our dynamic universe. While these cosmic collisions have shaped Earth's history and continue to pose risks to our planet, they also offer valuable opportunities for scientific discovery and exploration. Through continued research, vigilance, and collaboration, we can better understand and mitigate the impact of these celestial visitors, ensuring the safety and resilience of our planet for generations to come.。

Chemical and isotopic systematics of oceanic

Basl肘，
From SAUNDERS , eds) , 1989 , Magmatism in the Ocean Geological Socicty Special Publication No. 42 , pp. 313-345.
3 13
3 14
Major issues in the chemical evolution and geodynamics of the mantle
A first-order aim in the study of oceanic basa Its is to improve our understanding of the chemical
S.-s. Sun & W. F. McDonough
contribute to the geochemica\ and isotopic evolution of mantle reservoirs. The nature of mantle convection processes through time (whole mantle or layered mantle) is critical to our understanding of the chemica\ and thermal evo\ution of the Earth. The term ‘ reservoir' is used here in a general sense to refer to a part of the man tI e which has a partícular regíonal chemical and isotopic composítion , whereas the term ‘ componen t' speci缸" ally refers to a reservoir (or many reservoìrs) in thεmantle with an isotopically distinctive composition (eg HIMU , EM , MORB). This use of theterm ‘compone时， is similar to that in Zindler & Hart (1986). In essεnce each mantle reservoir carries an identifiable chemistry and isotopic fingerprínt of the specific processes and environments whích hav已 acted upon it. These composítional fingerprints reflect the responses to such factors as partìal melting under di在'erent P-T-X(C0 2 , water rich , melts or fluids) conditions , sediment subduction , and recycling of oceanic crust and asthenosphere through the subduction zone environment. Mantle differentiation processes through time Our understandin喜 of mantle differentiation 蹈' sociated with the Earth's accretion , core formation and the e挂rly history of man tI e-crust fractionation relies upon chemical and isotopíc studies of Archaean to modern volcanic rocks and other planetary bodies , petrological and chemical experiments carried out under hightemperature and high-prεssure conditions , and numerical modelling of the thermal evolution of the Earth. Even if some thermal models favour the pr出 ence of upper and lower mantle convection cells at present (eg Richter 1985) , there is no obvious reason to argue against whole-mantle convectÌon during the early history of the Earth. It is generaIl y assumed that the early Earth's man tI e temperature was higher (eg 2000 oC surface potential temperature) (Richter 1985) , which would favour vigorous , and probably chaotic , whole-mantle convection with possible largescale mantle meIting. Consequent1 y , it is very likely that the lower mantle would have been ìnvolved in the formation of the earliest enriched lithosphere , resulting in an incompatibleelement-dεpleted character , ie a non-primitive fractionated Iower mantle. At the same time , dense early-formed severely hydrothermaIl y altered mafic to ultramafic crust and lithospheric mantle may well have been rapidly recycI ed back i 挝o the convective mantle by meteorite

生命探测器的英文作文

生命探测器的英文作文Life Detector: Unveiling the Enigma of Extraterrestrial Life.In the vast cosmic tapestry, the question of extraterrestrial life has captivated the human imagination for centuries. As we embark on an ambitious quest to unravel the mysteries of the cosmos, the development oflife detectors has emerged as a crucial tool in our search for signs of life beyond Earth.Life detectors, also known as biosignatures, are scientific instruments designed to identify the presence of life by detecting specific chemical or physical signatures that are characteristic of living organisms. These signatures can range from the presence of complex organic molecules to the emission of waste products or the detection of specific biosignatures in geological samples.One of the most promising types of life detectors isthe chemical biomarker. Biomarkers are molecules that are produced by living organisms and can persist in the environment long after the organism itself has died. Someof the most common biomarkers include amino acids, carbohydrates, lipids, and nucleic acids. These molecules are essential for the basic functions of life, and their detection in extraterrestrial environments could provide strong evidence of past or present life.Another type of life detector is the isotopic biomarker. Isotopes are different forms of the same element that have the same number of protons but different numbers of neutrons. Isotopic ratios in the environment can beaffected by the presence of life, as certain isotopes are preferentially used by living organisms. By analyzing isotopic ratios in geological samples, scientists can infer the presence of life in an ancient environment.Life detectors can also be used to detect the presenceof waste products produced by living organisms. For example, the presence of methane in an extraterrestrial atmosphere could be a sign of microbial life, as methane is abyproduct of the metabolism of certain types of bacteria. Similarly, the detection of oxygen in an atmosphere could indicate the presence of photosynthetic life, as oxygen is a byproduct of photosynthesis.The development of life detectors has opened up new possibilities for exploring the question ofextraterrestrial life. By deploying life detectors on space probes and landers, scientists can analyze samples from other planets and moons in search of signs of life. The Mars rovers, for example, are equipped with a variety of life detectors that have been used to analyze the chemical composition of the Martian surface and search for evidence of past or present life.The detection of life beyond Earth would have profound implications for our understanding of the universe and our place within it. It would provide definitive proof thatlife is not unique to our planet and could potentially lead to new insights into the origins and evolution of life. The search for extraterrestrial life is an ongoing scientific endeavor, and the development of life detectors is a vitalpart of that quest. As we continue to explore the depths of space, the possibility of finding life beyond Earth is more tantalizing than ever before.。

同位素参考文献

参考资料这里列出部分书籍和文献目录，供初次进入实验室工作的研究生参考1、放射性同位素地球化学基本原理1) Dickin AP, 1995. Radiogenic Isotope Geology. Cambridge University Press (reprinted in 1997, 2000, 2002).Faure, G, 1986, Principles of Isotope Geology (Second edition). New York: John Wiley & Sons. pp589.(第一版出版于1977年，有中译本：G.福尔著，潘曙兰、乔广生译，同位素地质学原理。

北京：科学出版社，1983)2) 陈岳龙，杨忠芳，赵志丹编著，2005年。

同位素地质年代学与地球化学。

北京：地质出版社，441页。

2、同位素分析技术通论1) 黄达峰，罗修泉，李喜斌，邓中国等编著，2006年，同位素质谱技术与应用。

质谱技术丛书。

北京：化学工业出版，311页。

2）赵墨田，曹永明，陈刚，姜山编著，2006年，无机质谱概论。

质谱技术丛书。

北京：化学工业出版社，322页。

许荣华，张宗清，宋鹤彬，1985，稀土地球化学和同位素地质新方法。

北京：地质出版社，159页。

3、U-Th-Pb同位素分析1）Hanchar JM and Hoskin PWO, eds. 2003. Zircon. Reviews in Mineralogy and Geochemistry Vol. 53. pp500.2）Randall RP and Stephen RN, 2003. Zircon U-Th-Pb geochronology by isotope Dilution – thermal ionization mass Spectrometry (ID-TIMS). In: Hanchar JM and Hoskin PWO, eds. Zircon. Reviews in Mineralogy and Geochemistry Vol. 53. pp183-213.3）Randall R. Parrish, Randall R. Parrish, and Stephen R. Noble. 2003. Historical Development of Zircon Geochronology.Reviews in Mineralogy and Geochemistry Vol. 53. pp145-181.4）Chen F, Hegner E, Todt W (2000) Zircon ages and Nd isotopic and chemical compositions of orthogneisses from the Black forest, Germany: evidence for a Cambrian magmatic arc. Int J Earth Sciences 88:791–8025) Mattinson, J.M., 1994. A study of complex discordance in zircons using step-wise dissolution techniques. Contrib.Mineral. Petrol. 116, 117– 129.6) Krogh TE. 1982. Improved accuracy of U–Pb zircon ages by the creation of more concordant systems using an airabrasion technique. Geochim Cosmochim Acta Vol. 46: 637-6497）Krogh TE. 1973. A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations. Geochimica et Cosmochimica Acta Vol. 37: 485-4948) Poller U, Liebetrau V, Todt W (1997) U–Pb single-zircon dating under cathodelum- ine scence control (CLC-method):application to polymetamorphic orthogneisses. Chem Geol 139:287–2979) W. M. White. 1997. Geochemistry. Hopkins University Press. pp701.10) 沈渭洲编著，1994，同位素地质学教程。

地化名词

地化名词及解释1．有机化合物(organic compound):除CO2、碳酸盐岩和金属碳化物外的所有含碳原子化合物2．烃类化合物(hydrocarbons compound):指只含碳、氢元素的化合物，包括正构烷烃、支链烷烃、环烷烃和芳香烃。

3．非烃化合物/杂原子化合物（NSO化合物）(non hydrocarbon compounds/heteroatom compounds): 在组成石油、沥青和干酪根的有机化合物中，除C、H原子外的其它原子称为杂原子，含杂原子的化合物称为杂原子化合物或非烃化合物4．烷烃（saturated group）：只有碳氢单键的稳定分子称为烷烃或饱和烃5．立体化学(Stereochemistry):在分子中，原子之间的立体的或三维的关系称为立体化学6．同分异构体(isomeride)分子式相同而其结构基团排列不同的化合物称为同分异构体7．碳架异构：(carbon skeleton isomerism):碳架异构是由碳架中原子(atom)结合的顺序不同而产生的异构8．取代位置异构(coordination isomerism):取代位置异构是由于取代基在碳链或环上位置不同而产生的异构9．官能团异构(functional group isomerism) :官能团的异构是由于官能团的不同而形成的异构10．互变异构(tautomerism): 互变异构是由于活泼氢可以改变在分子内的位置产生的异构，该反应是可逆的11．立体异构(stereo isomerism):立体异构是指具有相同的分子式和相同的原子连接顺序，但是由于分子内的原子在空间排布的位置不同而产生的异构12．顺反异构(geometric Isomerism)：指由于共价键的旋转受到阻碍而产生原子在空间排布的位置不同的异构13．构象异构(conformational isomerism)：指由于分子内单键旋转位置不同而产生的异构。

桐柏秦岭岩群的两类变质作用_任留东

2
区域地质
秦岭造山带是一条具有复杂地壳结构和组成、经历了多
期地质过程的复合型造山带，中国南、北大陆于印支期完成了主体拼合而形成统一的中国大陆（张国伟等，2001 ）。以分为南秦岭、北秦岭构造单元，其中北秦岭主商丹断裂为界，要出露 3 个变质单元，由北向南，依次为宽坪群、二郎坪群和秦岭群，其间为构造接触。秦岭群主要由黑云斜长片麻岩、斜长角闪岩、石榴（蓝晶）夕线片麻岩，以及石英岩、变粒岩、石墨大理岩、石墨片岩及钙硅酸盐岩等组成（游振东等， 1991 ），为一套中深变质杂岩系，变质程度普遍达角闪岩相，局部达麻粒岩相，伴随强烈深熔混合岩化和多期次变形、岩浆侵入活动（游振东等，1991 ；王涛和杨家喜，1993 ），近年还在秦岭群北缘发现有一套高压超高压岩片，并报道有柯石英假象和锆石中含金刚石包裹体（ Hu et al. ，1995 ； Yang et al. ， 2003 ）。秦岭群现多称秦岭岩群。桐柏地区的秦岭岩群则产出麻粒岩（翟淳等，1997 ； Xiang et al. ，2010 ，2012 ）（图 1）。同位素年代学研究表明，榴辉岩的峰期变质年龄在 500 ～ 485Ma 之间， 480Ma 已经开始折返，并在 470Ma 左右折返到了地壳浅部（ Yang et al. ，2003 ；刘良等，2009 ，2013 ； Wang et al. ， 2011 ； Bader et al. ， 2013 ）。而在秦岭岩群南部松树沟地区也出露有高压麻粒岩及其退变的榴闪岩，其变质时代与北侧的榴辉岩相似，高压麻粒岩、榴辉岩变质时代 505Ma（张建新等， 2011 ）；低压角闪二辉麻粒岩变质时代为 440 ± 2Ma， 2011 ）。角闪岩相变质时代 426 ± 1Ma（张建新等，

澳大利亚布罗肯希尔(Broken Hill)铅锌银矿床

澳大利亚布罗肯希尔(Broken Hill)铅锌银矿床康欢;江思宏【期刊名称】《矿床地质》【年(卷),期】2015(034)006【总页数】4页(P1346-1349)【作者】康欢;江思宏【作者单位】中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037;中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037【正文语种】中文从全球范围来看，铅锌矿床的最主要类型是SEDEX型和MVT型。

而SEDEX型铅锌矿床以单个矿床储量巨大、品位高为特征，位于澳大利亚新南威尔士州西北部的布罗肯希尔(Broken Hill)铅锌银矿床就是一个典型实例。

它是世界上最大的铅锌银矿床之一，矿石储量2.8亿吨，矿石品位:w(Pb)为10%;w(Zn)为8.5%;w(Ag)为148 g/t(Walters，1996)，自1883年发现以来，已开采矿石约2亿吨。

布罗肯希尔铅锌银矿床在大地构造位置上处于南澳克拉通东部元古宙柯纳莫纳(Curnamona)省东南缘的布罗肯希尔地块(图1a)，该地块主要由古元古代—中元古代变质沉积岩和变质火成岩组成(Massimo et al.，2015)，出露的地层主要是威利雅马超群(Willyama Supergroup)，厚度7～11 km，原岩由泥质岩、砂屑泥质岩、砂屑岩、长英质和基性火山岩以及热水沉积岩组成，与上覆的阿德雷德系浅海相沉积物呈不整合接触。

威利雅马超群从下到上可划分为4个群，分别是塔卡林加(Thackaaringa)群、布罗肯希尔群、孙当(Sundown)群和帕拉根(Paragon)群。

威利雅马超群的长英质变质火山岩形成于1730～1690 Ma，并在1600 Ma经历了高级区域变质作用。

由北向南，区域变质作用由绿片岩相变为麻粒岩相，表明变质程度逐渐增强。

这次高级区域变质作用至少伴随了两期区域变形，并在退变质过程中发生了第三期变形作用(约1580 Ma)。

《信息检索与利用》综合检索报告

《信息检索与利用》综合检索报告一、Internet信息检索1.据《通志·氏族略》载：在京兆、河间一带的王氏族人，据说是周文王的第十五个儿子毕公高的后代，因此这一支系乃是出自于姬姓；在北海（今山东境内）、陈留（今河南开封附近）一带的王姓则传说是帝舜的后代，这一支系出自于妫姓之王；不仅华夏族的王室之后不少是以王为姓，许多少数民族的部落首领、执政者的后代也有以王为姓的，其意与上述出自姬姓、妫姓、子姓的王氏大致相同。

王氏的众多分支中数来仍以源自周文王姬姓子孙的那一支名气最大。

这一支王姓源自原来的周朝，也即今天的甘肃、陕西西安一带，其后来的主要分封之地在今山东省境。

根据考证，晋朝中兴名臣王导就是这支王氏在山东繁衍的子孙，其子孙世代簪缨，使王氏成为一时望族。

2.洛阳名胜有龙门石窟、白马寺、牡丹、汉光武帝陵、杜甫墓等等。

洛阳特产有黄河大鲤鱼、牛心柿、唐三彩、河洛奇石、洛阳青铜器等等。

洛阳有名的小吃餐馆一般都在老城区，可以坐出租车到达。

3.题名：《核工业铀资源勘查遥感应用的创新与数字勘查技术系统研究》作者：刘德长赵英俊仉宝聚王霞题名：《资源勘查图件计算机辅助编绘系统的结构分析与开发策略研究》作者：刘刚汪新庆李伟忠田宜平二、综合课题检索1.检索课题题目：金矿床地质特征及成因类型2.检索词：金（gold）矿床(deposit) 地质特征(geological characteristics) 成因类型(genetic types)3.检索程序：本课题题目是有关地质采矿专业的课题，专业性很强。

可以采用的检索系统有google的学术搜索，维普资讯（），中国期刊网，SCI，EI等。

检索关键词包括金矿床、地质特征、成因类型。

检索提问式包括：文献类型选择，查询范围选择，查询年限选择，输入关键词。

4.检索结果：（1）《平顶山岩金矿床地质特征及成因类型》摘要：一、地质概况平顶山金矿床位于黑龙江省东北部嘉荫县境内，隶属于兴凯湖---布列亚山地块区，佳木斯隆起带。

小学上册第十四次英语第2单元测验试卷

小学上册英语第2单元测验试卷考试时间：80分钟（总分:120）A卷一、综合题(共计100题共100分)1. 填空题：I received a new ________ (玩具) from my parents.2. 选择题：What is the name of the famous scientist known for his theory of general relativity?A. Albert EinsteinB. Isaac NewtonC. Niels BohrD. Richard Feynman3. 选择题：What do we call a tool used for writing?A. BrushB. PencilC. EraserD. Ruler4. 选择题：What do you call a person who studies rocks?A. BiologistB. GeologistC. ChemistD. Astronomer答案:B5. 选择题：What do we call the season after winter?A. SpringB. SummerC. FallD. Autumn答案:AThe ________ is known for its friendly nature.7. 听力题：The boiling point of water is _______ degrees Celsius.8. 听力题：She is wearing a warm ___. (sweater)9. 听力填空题：My favorite outdoor activity is __________ because it’s adventurous.10. 听力题：The capital of Belarus is _______.11. 填空题：I enjoy building things with my ____. (积木)12. 填空题：I love to go ________ (滑板) with my friends.13. 填空题：The _______ (Indigenous peoples) have lived in America for thousands of years.14. 听力题：My mom enjoys making ____ (jams) from fruits.15. 选择题：What is the name of the famous volcano in Italy?A. Mount FujiB. Mount VesuviusC. Mount St. HelensD. Mount Kilimanjaro答案: B. Mount Vesuvius16. 填空题：We can _____ (cultivate) plants in our garden.17. 选择题：What do we call a person who flies airplanes?A. PilotB. EngineerC. MechanicD. Stewardess答案: AThe ______ (蓝鲸) is known to be the largest animal ever.19. 听力题：The movie was very ___ (funny).20. sh Civil War was fought from ________ (1936) to 1939. 填空题：The Span21. 听力题：I see a _____ (tree/bush) in the yard.22. 听力填空题：I feel excited when I __________ because it makes me __________.23. 填空题：A ________ (植物观察志愿者) contributes to knowledge.24. 填空题：The frog's croak is a sign of ______ (繁殖).25. 填空题：This is my mother, she is a __________ (医生) at the hospital.26. 填空题：The _____ (cantaloupe) is a sweet melon.27. 听力题：The Earth's crust is constantly being ______ by geological forces.28. 选择题：What do you call the baby of a kangaroo?A. CubB. JoeyC. CalfD. Kit答案:B29. 选择题：Which vehicle travels on water?A. CarB. AirplaneC. BicycleD. Boat答案:DShe is wearing a pretty ___. (scarf)31. 填空题：The _____ (洋娃娃) can wear different dresses.32. 填空题：The hummingbird is the only bird that can fly ______ (倒退).33. 填空题：I saw a ______ (蜗牛) on the sidewalk.34. 填空题：I enjoy writing letters to my ______ (亲戚). It helps us stay connected even when we’re far apart.35. 选择题：How many seconds are there in a minute?A. 30B. 60C. 90D. 12036. 选择题：What is the process called when a caterpillar becomes a butterfly?A. MetamorphosisB. EvolutionC. TransformationD. Development答案:A37. 听力题：The __________ is where tectonic plates converge.38. 听力题：We are going to ___ a concert. (attend)39. 听力题：The chemical formula for iron(II) chloride is ______.40. 听力题：The study of Earth's geological history is important for understanding ______.41. 选择题：What do you call a frozen form of water?A. IceC. LiquidD. Vapor答案:A42. 填空题：My mom loves to __________ (旅行).43. 选择题：What do we call a young penguin?A. ChickB. PupC. CalfD. Kit答案:A. Chick44. 填空题：We water the ________ every day.45. 选择题：Which planet has the longest day?A. EarthB. VenusC. MarsD. Mercury46. 听力题：The __________ is a region of the Earth’s surface that is above sea level.47. 填空题：I enjoy planting ______.48. 听力题：A polymer is a large molecule made up of many ______.49. 听力题：Metals can conduct __________.50. 填空题：My dog loves to play with a ______ (球) in the park.51. 选择题：What do we use to cut paper?A. ScissorsB. TapeC. Glue答案:A52. 填空题：I want to _______ (了解)更多关于艺术.53. 听力题：The chemical formula for hexanoic acid54. 听力题：The chemical formula for strontium hydroxide is _______.55. 听力题：I enjoy _____ (观看) movies at home.56. 听力题：The chemical formula for sodium fluoride is _____.57. 填空题：The movie starts at _______ (七点).58. 选择题：What is the name of the famous fictional detective?A. Sherlock HolmesB. Hercule PoirotC. Miss MarpleD. Philip Marlowe答案:A59. Mountains are located in ________ (落基山脉位于________). 填空题：The Roma60. 听力题：I like to ride my _____ (bike/car) to school.61. 听力题：Space probes have helped us learn about the outer ______.62. 选择题：Which candy is shaped like a bean and comes in many flavors?A. ChocolateB. Jelly BeanC. LollipopD. Gum答案：B63. 选择题：Which one is a fruit?A. LettuceB. PotatoC. TomatoD. Carrot答案:C64. 选择题：What do we call the game played on a board with black and white squares?A. Snakes and LaddersB. ChessC. CheckersD. Monopoly65. 填空题：The _____ (肥料) helps improve soil quality.66. 听力题：My favorite game is ______ (Scrabble).67. 听力题：Light travels faster than ______.68. 填空题：The ________ is a type of plant that has thorns.69. 选择题：What do we call a person who studies the history of specific cultures?A. AnthropologistB. HistorianC. ArchaeologistD. Sociologist答案: A70. 听力题：My sister is good at playing ____ (board games).71. 选择题：What do we call a long piece of writing, often fictional?A. PoemB. StoryC. EssayD. Novel72. e _______ (爬行) animals. 填空题：Snakes a73. 填空题：I like to play with my ________ at home.74. 听力题：The chemical symbol for mercury is __________.75. 填空题：The _____ (greenhouse) helps plants grow year-round.76. 听力题：The city of Baghdad is the capital of _______.77. 听力题：The _____ (piano) is out of tune.78. 听力题：The symbol for copper is _____.79. 听力题：A ______ is a type of fish that can be found in rivers.80. 选择题：How many zeros are in one hundred?A. OneB. TwoC. ThreeD. Four答案: B81. 填空题：I saw a _______ (大象) at the zoo yesterday.82. 听力题：The chemical symbol for magnesium is ______.83. 小狐狸) has bright, orange fur. 填空题：The ___84. 选择题：How many players are on a basketball team?A. 5B. 6C. 7D. 8答案:A. 585. 选择题：What is the capital of Morocco?A. CasablancaB. RabatC. MarrakechD. Tangier答案:B86. 听力题：The law of conservation of energy states that energy cannot be ______.87. 选择题：What is the name of the fairy tale character who lives in a tower?A. CinderellaB. RapunzelC. Snow WhiteD. Belle88. 填空题：My ________ (玩具) is colorful and fun.89. 听力题：I have _____ (one/two) pet cats.90. 听力题：My aunt enjoys attending ____ (concerts).91. 填空题：The stars are ________ (闪闪发光).92. 填空题：The __________ (历史的动态) reflects society.93. 听力题：She _____ (likes/love) to read stories.94. 选择题：What is the name of the fairy in "Peter Pan"?A. Tinker BellB. WendyC. CinderellaD. Ariel答案:A95. 填空题：My favorite thing to do at home is ______.96. 听力题：We have a ________ (debate) about issues.97. 选择题：What is the color of a typical banana?A. GreenB. YellowC. RedD. Blue98. 填空题：My ___ (小兔子) has long ears and a fluffy tail.99. 听力题：A horse gallops across the _____.100. 填空题：The __________ (峭壁) overlooks the sea.。

2005_Isotopes and sustainability of ground water resources(华北)_陈宗宇

Isotopes and Sustainability of Ground Water Resources,North China Plainby Chen Zongyu 1,2,Nie Zhenlong 1,Zhang Zhaoji 1,Qi Jixiang 1,and Nan Yunju 1AbstractGround water in deep confined aquifers is one of the major water resources for agricultural,industrial,and domestic uses in the North China Plain.Detailed information on ground water age and recharge is vital for the proper management of these water resources,and to this end,we used carbon 14of dissolved inorganic carbon and tritium in water to measure the age and determine the recharge areas of ground water in the North China Plain.These isotopic data suggest that most ground water in the piedmont part of the North China Plain is <40years old and is recharged locally.In contrast,ground water in the central and littoral portions of the North China Plain is 10,000to 25,000years old.The d 18O (d D)values of this ground water are 1.7&(11&)less than that in the piedmont plain ground water and possibly reflect water recharged during a cooler climate during the last glaci-ation.The temperature of this recharge,based on d 18O values,ranges from 3.7°C to 8.4°C,compared to 12°C to 13°C of modern recharge water.The isotopic data set combined indicates that ground water in the central and litto-ral part of the North China Plain is being mined under non–steady state conditions.IntroductionGround water is one of the most important natural re-sources in the North China Plain (Figure 1).It provides ~56%of the water supply for more than 100million peo-ple.Ground water is also the source of much of the water used for irrigation.The exploitation of ground water from deep confined aquifers on a large scale started in the 1970s.Since many developing cities are located on the plain,pumping of ground water is increasing annually,and the potentiometric surface of the aquifers is continu-ally declining.Local cones of influence have developed in Beijing,Tianjin,Baoding,Shijiazhuang,Hengshui,and Cangzhou,and since 1990,some of these cones in the central part of the plain have merged.The depths to thepotentiometric surface in the central parts of these cones have declined from 3to 80m from 1968to 1998(Zhang et al.2000).Two fundamental questions related to the sustainability of the ground water resource are1.How old is this potable water supply?2.What is the recharge of the deep confined aquifer?(Are we ‘‘mining’’ground water?)The most common approach used to answer these questions is to apply natural chemical tracers (Nativ and Riggio 1989;Wood and Sanford 1995;Clark et al.1998;James et al.2000).Naturally occurring stable (H,O)and radiogenic (3H,14C)isotopes of water have been widely used over the past 40years to address problems related to ground water recharge,delineation of flow systems,and quantification of mass-balance relationships (Fontes 1980;Gonfiantini 1986;Siegel 1991;Gat 1996;Clark and Fritz 1997;Rozanski et al.1997).We herein report the results of a study designed to analyze the age and recharge of ground water in deep confined aquifers in the North China Plain by using a suite of isotopic tracers to test the hypothesis that deep ground water may now be exploited at rates that exceed natural recharge.1Departmentof Water Resources and Environmental Engi-neering,China University of Geosciences,100083,29Xueyaun Lu,Haidian District,Beijing,People’s Republic of China.2Corresponding author:Institute of Hydrogeology and Envi-ronmental Geology,Chinese Academy of Geological Sciences,050803,Zhengding,Hebei,People’s Republic of China;fax:(86)-311-8021225;chenzy@Received May 2002,accepted April 2004.Copyright ª2005National Ground WaterAssociation.Study AreaThe North China Plain overlies a thick Cenozoic sed-imentary basin covering~150,000km2and is bordered by the Taihang Mountains to the west,by the Bohai Sea to the east,by the Yanshan Mountain to the north,and by the Yellow River to the south.The flat plain slopes gener-ally west to east from an altitude of~100m above sea level(a.s.l.)to~1to2m a.s.l.The plain geographically consists of three parts:(1)the piedmont pluvial plain;(2) the central alluvial and floodplain;and(3)the littoral delta plain(Figure1).The climate is continental,semi-arid,with mean annual temperatures of~12°C and sum-mer maximum and winter minimum of46°C and228°C, respectively(Wu1992).The annual precipitation ranges from500to600mm(Chen1999).Precipitation is domi-nated by the summer monsoon from June to August (Zhang et al.2000).The mean potential evaporation ranges from1100to1800mm(Liu and Wang1992).The entire North China Plain is drained by the Haihe River, the South Canal connecting the Yellow and Haihe rivers, the Luanhe River,and their tributaries.Most surface water flow occurs in the rainy season.The rocks underlying the North China Plain are Archean to Quaternary in age.The bedrock consists of Archean gneiss and Proterozic carbonate rocks overlain by thick Tertiary and Quaternary deposits.The Quater-nary deposits are from150to600m thick and consist of fluvial deposits in the piedmont plain,alluvial and lacus-trine deposits in the central plain,and alluvial deposits interbedded with marine deposits in the littoral plain (Chen1999).There are four aquifers(Chen1999):(1)the‘‘Holo-cene formation’’;(2)an upper Pleistocene formation;(3) a middle Pleistocene formation;and(4)a lower Pleisto-cene formation(Figure2).Aquifer1is an unconfined aquifer,~60m thick,con-sisting of coarse-grained sand in the piedmont plain to fine-grained sand in the littoral plain.Ground water is fresh in the piedmont plain but saline in the central and littoral plains(total dissolved solids[TDS]>2g/L).Iso-tope data(Zhang et al.1987)show that this saline water is the result of evaporative concentration.Aquifer2is a shallow confined aquifer,60m thick, consisting of sandy gravel,medium to fine sand.Asinaquifer1,ground water is saline,with TDS>2g/L,from the central to the littoral plains.Zhang et al.(1987)sug-gested that the accumulation of salt in these sediments was caused by continental salinization.Aquifer3,more than90m thick,is a confined aqui-fer consisting of sandy gravel in the piedmont plain to medium to fine sand in the central and the littoral plains. In contrast to aquifers1and2,ground water is fresh, with TDS of0.3to0.5g/L(Chen1999).Aquifer4is50to60m thick and>350m deep and consists of cemented sandy gravel and a thin layer of weathered sand20to40m thick.Dissolved solids in this water are<1000mg/L.From the central plain to the littoral plain,the main sand layer changes from medium-fine sand ~30m thick to fine sand and silts~20m thick.TDS in this water are~500to1500mg/L and1500to2000mg/L in the central and littoral plain,respectively.A recent study (Zhang et al.2000)suggests some of this water originate from induced recharge from overlying aquifers.Both aqui-fers3and4are the targets of exploitation.Isotopic investigations of water in shallow aquifers in the North China Plain(Zhang et al.1987;Liu et al. 1997)showed that the confined aquifer in the North China Plain is recharged at adjacent piedmont areas,and the artesian system discharges water into overlying shal-low aquifers that contain saline water.Their studies,how-ever,focused on the isotopic composition of water in the shallow unconfined aquifer rather than the deep poten-tially exploitable ground water resource.MethodsSamples of ground water were collected for isotope analyses in August1999from the deep confined aquifer along a flowpath from the outcrop to the discharge area (Figure1).Samples for d18O,d D,and tritium in ground water were collected in1-L glass bottles with airtight caps.The samples for carbon isotope determination in dissolved inorganic carbon(DIC)(d13C)were collected by precipitating BaCO3by adding excess BaCl2to120L of water,previously brought to pH 12by addition of NaOH.Temperature and pH were measured in situ with a portable Hanna pH meter that was calibrated before use.Alkalinity was measured by Gran titration.Isotopic analyses were done by the Open Laboratory of Environ-mental Geology and the Central Laboratory of Hydro-geology,the Ministry of Land Resources,China.Stable isotopes of ground water were determined using the CO2equilibration method for18O/16O ratios(Epstein and Mayeda1953)and the zinc-reduction method for D/H ratios(Coleman et al.1982),followed by analysis with a Finnigan MAT isotope ratio mass spectrometer (MAT251).Analyses are reported in standard d notation representing per mill deviations from the standard mean ocean water(SMOW)standard.Precision for d D and d18O are±1.0&and±0.1&,respectively.Tritium was determined on electrolytically enriched water samples by low-level proportional counting,and re-sults are reported in tritium units(TU),with a typical error of±1TU(Eichinger et al.1980).The14C of DIC was determined radiometrically by liquid scintillation counting after conversion to benzene(Fontes1971).The detection limit(in percent modern carbon[pmc])is between0.7and 1pmc.The d13C analyses were determined on a mass spectrometry and reported as d values relative to Pee Dee belemnite(PDB)standard.Precision for d13C is±0.2&. The analytical results are presented in Table1.The stable isotopic composition of ground water was used to evaluate whether recharge to the deepaquifersT a b l e 1A n a l y t i c a l R e s u l t s f o r G r o u n d W a t e r i n t h e N o r t h C h i n a P l a i nA r e aN o .D e p t h (m )S c r e e n L e n g t h (m )T (°C )p H H C O 32(m g /L )d 18O (&)d D (&)3H (T U )d 13C (P D B )14C (p m c )14CA g e (U n c o r r e c t e d ,k aB .P .)14C A g e (V o g e l ,k a B .P .)14C A g e (T a m e r ,k a B .P .)14C A g e (P e a r s o n ,k a B .P .)P i e d m o n t p l a i n 35150100–14935.07.60216.6210.2273129.331.359.67.24.26.83315016.07.46360.329.22671129.363.873.71.3M o d e r n 0.93211015.07.48336.829.42694429.766.163.461M o d e r n 1314020–3711.07.40289.828.326332210.4111.07M o d e r n M o d e r n M o d e r n M o d e r n 307030–7813.07.40271.527.726427210.359.054.42M o d e r n 2.429150125–14817.07.40241.028.9267629.662.313.91.5M o d e r n 1.428251200–24719.07.30198.329.0266129.424.5011.69.26.88.927200150–19819.07.30201.428.9269129.576.922.2M o d e r n M o d e r n M o d e r n 26310260–30719.08.17269.028.9270129.437.378.15.82.55.525265190–26321.37.42265.428.92701210.256.304.72.4M o d e r n 2.7C e n t r a l p l a i n34300223–29530.07.20228.8211.6279<129.96.6622.420.019.120.124350260–34520.57.85112.3211.0274<129.818.4014.011.68.511.723310260–30721.08.00111.1211.1279<129.616.4214.912.69.412.422340255–33622.07.6994.6210.8285129.910.9318.315.912.916.021380282–37523.17.70103.7210.8282229.310.2218.916.513.516.020330195–32520.57.90213.6210.5278129.612.8417.014.611.514.519380241–37619.07.70466.8210.5280129.28.0320.818.515.518.018280200–26018.58.00161.7210.8275128.715.2515.513.210.012.217300225–29822.08.00162.3210.8276129.112.2317.415.011.814.416400285–39718.08.10169.0210.7280128.913.5616.514.110.913.415370292–36031.88.20144.0210.7280127.86.2922.920.517.218.61428020.58.20143.4210.6283125.511.6517.815.412.210.713300220–29824.08.20140.3210.3282228.06.8522.219.816.518.112310280–30518.98.10146.4210.5282128.311.0918.215.812.614.511320282–31818.87.90263.6211.7280<128.69.9419.116.713.615.710300249–29818.07.70341.7210.4277229.013.4716.614.211.213.59370290–34520.07.80335.6210.2279<1210.97.1221.819.516.420.48345300–33823.07.75314.3210.12791211.518.3014.011.78.613.0L i t t o r a l p l a i n7360340–35721.07.85335.6210.22812210.17.2521.719.316.219.66350240–29024.57.90300.8210.02781210.210.3318.816.413.316.85378215–37522.07.75277.6210.12767211.211.1018.215.812.816.94380280–37624.07.80387.529.6272127.918.5213.911.68.59.83413310–37025.57.85241.0210.02803210.910.2618.816.413.317.42437370–43021.77.90360.029.9274228.714.0816.213.810.712.9170034.07.80329.529.4277<1211.12.4430.728.325.229.4488C.Zongyu et al.GROUND WATER 43,no.4:485–493occurred under the same general climatic condition as current conditions.Tritium activity was measured to determine where modern recharge has penetrated the aquifers.Tritium activity in precipitation was elevated thousands of times more than background as a result of atomic weapons testing in the Pacific Ocean during the early1960s.This water can be identified in the subsur-face by tritium activities greater than~20TU(Clark and Fritz1997).The stable isotopes of carbon in DIC were measured to evaluate geochemical processes,such as methanogenesis and sulfate reduction,and14C of inor-ganic carbon was measured to determine ground water age(Clark and Fritz1997).ResultsThe results of isotopic tracer analysis in this study show three distinct groups of water(Table2,Fig-ure3).One group is found in the piedmont plain,and two groups are found in the central and littoral plains.d D and d18OThe isotopically heaviest water was from the pied-mont,and the isotopically lightest water was from central plain(Figure3).With the exception of six enriched2H samples collected from the central plain(11,17,18,23, 24,and34),all samples plot below,but parallel to,the meteoric water line of d D=7.4d18O16.3(Zhang et al. 1991,derived from data obtained at Shijiazhuang station of the International Atomic Energy Agency network for China,located at114.25°N and38.02°E).The fitted least squares line for these data is d D=7.3d18O23.6 (Figure3);difference in the intercept between this regres-sion line and the one at Shijiazhuang probably is related to local hydrometeorological effects.Along the flowpath,d D values decrease from262.7&(no.31)to270&(no.25), while d18O values decrease from27.7&(no.30)to 29.7&(no.25)in the piedmont plain(Figure4,Table2). In the central plain,d18O values range from11.0& (no.24)to10.1&(no.8),and d D values vary from 285&(no.22)to279&(no.8).In the littoral plain,d D and d18O values range from10.2&(no.7)to29.4&(no.1)and from281&(no.7)to272&(no.4),respectively. d18O values of water in the central plain are,on average, 1.7&less than in the piedmont plain water,and d D values are11&less than in the piedmont plain water.Tritium(3H)Generally,the tritium contents of ground water are higher in the piedmont plain than in the littoral area and higher in shallow aquifer than in deep aquifer(Figures4 and5).In the piedmont plain,only four samples(30,31, 32,and33)had tritium activity>6TU.These four sample sites are in a recharge area from wells with depths <150m.The rest of samples were collected at depths of more than150m and their tritium content is<2TU, which is effectively background level.The tritium content of two samples(3and5)from the littoral plain is rela-tively high,probably caused by mixing in wells.14C of DICThe14C values of DIC generally decrease with increasing depth and distance from the recharge area along the flowpath(Figures4and5)from111to10.2pmc within the first100km and then from18.52to2.44pmc (Figure4).In the piedmont plain,the14C activity for sample no.31collected from a shallow well of40-m depth is 111pmc.The activities for sample nos.29,30,32,33, and35,collected from wells of70-to150-m depth,rangeTable2Summary of Isotopic Compositions in AquifersTracer Piedmont Plain Central Plain Littoral Plain 14C content(pmc)24.5to111.1 6.3to18.4 2.4to18.5 14C age(ka B.P.)7to modern20to1025to11d18O(&)27.7to210.2210.1to211.729.4to210.2 d D(&)263to273274to285272to281 18O temperature(°C)15to108to410to83H(TU)1to44<21to7d13C(PDB)29.3to210.425.5to211.527.9to211.2 pH7.30to8.177.20to8.207.75to7.90from31.4to66.2pmc.The14C activities for sample nos. 25,26,27,and28from251-to310-m depth range from 24.5to56.3pmc.The14C activities for samples collected from wells in the central plain that penetrate to deep confined aquifers are6.3to18.4pmc.The14C values for samples collected from wells in the littoral plain are18.5to7.3pmc.Sam-ple no.1,however,was collected from a well of700-m depth,and its14C content is2.4pmc.DiscussionAge of Ground Water in the Confined Aquiferd18O(d D)values for ground water in the central plain and littoral plain portions of the North China Plain are1.7&(11&)less than for the piedmont plain ground water.This depletion is similar to that found in water from other deep confined systems(e.g.,Sonntag et al. 1979;Dray et al.1983;Rozanski1985;Clark and Fritz 1997).A few samples from the central plain are enriched in deuterium.Chemical processes,such as methano-genesis and sulfate reduction,can cause d D values to move up from the local meteoric water line without corre-sponding shifts in d18O values.The2H enrichment for the six samples from the central plain(Figure3)probably is related to methanogenesis because the d13C DIC values of this water are not very low and therefore inconsistent with sulfate reduction by an organic substrate.In fresh water, methanogenesis generally proceeds by the CO2reduction pathway,which enriches the residual DIC.The d13C enrichment of a few parts per mill in this water(Table1)is consistent with the hypothesis of CH4generation by CO2reduction.Future work will hopefully determine if geochemical process affected or currently affects the water chemistry in the aquifer.Much of the deep confined ground water in the North China Plain is probably thousands of years old.This paleo ground water is often characterized by depleted18O and2H with respect to modern recharge because it was recharged during a colder climate in the Pleistocene.The values of both d D and d18O in ground water from the deep aquifers of the North China Plain decrease by~20& and2&(SMOW),respectively,between where ground water has demonstrably modern14C and3H signatures, and where14C is consistently<20pmc and3H is non-detectable(Figure4).This relationship suggests that ground water beneath the central to littoral plains was most likely recharged during the late Pleistocene.Ground water in the piedmont plain(sample nos.29, 30,31,32,and33)contains considerable amounts of tritium and therefore is<40years old.Conversely, ground water with tritium content<2TU is more than40 years old.Much of the carbon in ground water derives from gaseous CO2in the vadose zone.However,this carbon with modern activity of14C(~100pmc)is usually diluted by low–14C activity carbon dissolved from minerals dur-ing ground water recharge.The interpretation of ground water ages based on14C analyses of DIC can be further complicated by isotope exchange reactions between the carbonate phases and microbial respiration.There are several methods to correct the initial14C activity for dead-carbon dilution(e.g.,V ogel1970;Tamers1975; Pearson and White1967;Mook1976;Fontes and Garnier 1979).Most correction methods are based on isotopic and chemical mixing calculations.Isotopic mixing is based on the hypothesis that13C can be used as an analogue for14C because both have a similar chemical behavior.Chemical mixing is based on the stoichiometric relationships of car-bonate mineral dissolution.To calculate ground water age in the North China Plain,we considered as a first approximation that DIC does not exchange with carbonate sediments.In this case, ~50%input of the carbon in DIC is derived from soil car-bon dioxide and the other half from dissolving carbonate minerals(Tamers1975)—half of the carbon introduced into the ground water is live carbon and half is dead car-bon.We also assumed that all of the carbon dioxide comes from the soil zone and that all the bicarbonate is derived from dissolving carbonate minerals.The ground water ages(Table1)calculated by the Tamer model are not far from ages calculated from an alternative approach, wherein75%of the DIC is assumed to be derived from soil carbon dioxide(V ogel1993).In both cases,we assumed that the d13C for mineral carbonate was0&and that for soil carbon dioxide was213&(V ogel1993). Thus,the age of tritium-bearing water in the piedmont plain is from7ka B.P.to modern.The ground water in the central plain falls in an age bracket of10to20ka B.P.,and the ground water age in the littoral plain is up to 25ka B.P.Ground Water RechargeThe isotopic data indicate that ground water in the deep confined aquifer was recharged under conditions different from today.Relatively modern ground water oc-curs in the piedmont plain,which is recharged locally from precipitation.The14C activity of this water ranges from~25to111pmc and has equivalent14C ages<7ka B.P.This ground water was recharged during the late Holocene.The tritium in some of these watersamplessuggests that they were even recharged during the past 40years.Based on the temperature-d18O correlation for precipitation in China(Zheng et al.1983;d18O=0.35t2 13.0&),calculated recharge temperature for water in the piedmont plain ranges from10.3°C to15°C,which agrees with the modern annual mean air temperature.Thus,the recharge time of ground water in the piedmont plain could be as short as a few decades and the water no older than a few thousand years.The active ground water recharge zone has a thickness of~150m.Here,in the piedmont plain,ground water is renewable.In contrast,ground water in the central plain is char-acterized by14C content between6.3and18.4pmc,and equivalent14C ages are10to20ka B.P.The tritium con-tent of most samples is<1TU.The d18O value ranges from210.1&to211.7&and is less by1.7&than in the piedmont plain.Calculated recharge temperature ranges from3.7°C to8.4°C,~4°C to8°C lower than in the pied-mont plain.Given the present-day temperature-elevation gradient,20.45°C/100m(Zhang1991),the temperature at the maximum elevation of recharge,1000m(Chen 1999),should be only3.6°C to4.5°C lower than in the recharge area.Therefore,elevation cannot be the sole con-tributor to the observed isotopic depletion.It is possible that recharge took place during the past glacial period when recharge was greater because of the lack of vegeta-tion in colder,winter periods.This conclusion agrees with the results of a pollen study(Kong and Du1980)and paleo-hydrology(Shi and Yin1996).The14C activity of ground water in the littoral plain is<18.5pmc,and equivalent14C ages are11to25ka B.P.The d18O and d D values of ground water here is slightly higher than in the central plain.Calculated re-charge temperature based on observed d18O values ranges from8°C to10°C.The lowest14C content of sample no.1,with14C age~25ka B.P.may reflect water that was recharged during the past glacial period. Conclusions and Implications for Water Resources ManagementThere are very important and practical implications for water resources management in knowing the age of ground water in the North China Plain.The calculated ground water ages and their distributions(Figure6)show that modern-age water is only found in the piedmont plain. Ground water in this zone is a renewable resource,and water exploitation is potentially sustainable.In contrast, 14C data,the stable isotopic composition of the ground water,and the lack of tritium combined show that ground water in other parts of the deep confined aquifer may date, in part,to Pleistocene times.These aquifers are being ‘‘mined’’;more water is being withdrawn than can be re-plenished and the resource is inherently finite and limited. AcknowledgmentsThis work was financially supported by the National Natural Science Foundation of China(NSFC grant no.4047215).The authors would like to thank Ronit Nativ, Michael Burns,and David C.Gosselin for helpful com-ments and review of the manuscript.Special thanks to Don Siegel for reviewing multiple versions of the manu-script and for help in editing the document.We also thank Xu Jiaming for his help during sampling water and Halldor Armannsson for his contribution to language revision.ReferencesChen,W.H.1999.Ground Water in Hebei.Beijing,China: Seismological Press.Clark,I.D.,and P.Fritz.1997.Environmental Isotopes in Hydro-geology.New York:Lewis Publishers.Clark,J.F.,M.L.Davisson,G.B.Hudson,and P.A.Macfarlane.1998.Noble gases,stable isotopes,and radiocarbon as tracers of flow in the Dakota aquifer,Colorado and Kansas.Journal of Hydrology211,no.1/4:151–167.Coleman,M.L.,T.J.Sheppard,J.J.Durham,J.E.Rouse,and G.R.Moore.1982.Reduction of water with zinc for hydrogen isotope analysis.Analytical Chemistry54,no.6:993–995. Dray,M.,R.Gonfiantini,and G.M.Zuppi.1983.On the isotopic composition of groundwater in the southern Sahara.In Paleoclimates and Paleowaters:A Collection of Environ-mental Isotope Studies,ed.M.Dray,R.Gonfiantini,andG.M.Zuppi,STI/PUB/621,187–199.Vienna,Austria:IAEA. Eichinger,L.,M.Forster,H.Rast,W.Rauert,and M.Wolf.1980.Experience gathered in low-level measurement of3H in water.In Low-Level3H Measurement,IAEA-TECDOC-246,43–64.Vienna,Austria:IAEA.Epstein,S.,and T.Mayeda.1953.Variation of18O content of waters from natural sources,Geochimica et Cosmochimica Acta4,no.5:213–224.Fontes,J.-C.,and J.M.Garnier.1979.Determination of the ini-tial14C activity of the total dissolved carbon—A review of the existing models and a new approach.Water Resources Research15,no.2:399–413.Fontes,J.Ch.1980.Environmental isotopes in ground water hydrology.In Handbook of Environmental Isotope Geo-chemistry,ed.P.Fritz and J.Ch.Fontes,75–140.Am-sterdam,The Netherlands:Elsevier Science Publications. Fontes J.Ch.1971.Un ensemble destine a la mesure de l’activite du radiocarbon naturel par scintillation liquide.Revue de Geographie Physique et de Geologie Dynamique2,XIII, fasc.1:67–86.Gat,J.R.1996.Oxygen and hydrogen isotopes in the hydrologic cycle.Annual Review of Earth and Planetary Sciences24, 225–262.Gonfiantini,R.1986.Environmental isotopes in lake studies.In Handbook of Environmental Isotope Geochemistry,vol.2, ed.P.Fritz and J.C.Fontes,113–168.Amsterdam,The Netherlands:Elsevier.James,E.R.,M.Manga,T.P.Rose,and G.B.Hudson.2000.The use of temperature and the isotopes of O,H,C,and noble gases to determine the pattern and spatial extent of ground water flow.Journal of Hydrology237,no.1/2:100–112. Kong,Z.C.,and N.Q.Du.1980.Vegetational and climatic changes in the past30,000–1000years in Beijing.Acta Botanica Sinica24,no.4:330–338.Liu,C.F.,P.Y.Wang,and L.Zhou.1997.The environment sig-nificance of H,O,C and Cl isotopic composition in ground water of Hebei Plain.Earth Science Frontiers(China Uni-versity of Geosciences,Beijing)4,no.4:267–274.Liu C.F.,and P.Y.Wang.1992.The environment significance of isotope composition in ground water of Hebei Plain.In Pro-ceedings of International Workshop on Ground Water and Environment,382–386.Beijing,China:Seismological Press. Mook,W.G.1976.The dissolution-exchange model for dating ground water with carbon-14.In Interpretation of492 C.Zongyu et al.GROUND WATER43,no.4:485–493Environmental Isotope and Hydrochemical Data in Ground Water Hydrology,STI/PUB/429,213–225.Vienna,IAEA. Nativ,R.,and R.Riggio.1989.Meteorologic and isotopic char-acteristics of precipitation events with implications for ground-water recharge,Southern High Plains.Atmospheric Research23,no.1:51–82.Pearson,F.J.,and D.E.White.1967.C-14ages and flow rates of water in Carrizo Sand,Atascosa County,TX.Water Re-sources Research3,no.1:251–261.Rozanski,K.1985.Deuterium and oxygen-18in European groundwaters-links to atmospheric circulation in the past.Chemical Geology(Isotope Geoscience Section),52, 349–363.Rozanski,K.,S.J.Johnsen,U.Schotterer,and L.G.Thompson.1997.Reconstruction of past climates from stable isotope records of palaeo-precipitation preserved in continental archives.Hydrological Sciences Journal42,no.5:725–745. Shi,D.H.,and X.Yin.1996.A latitudinal section studied on the evolution of terrestrial water system in northern China since late Pleistocene.In30th International Geological Congress Abstracts,vol.1,92.Beijing,China:Geological Publishing House.Siegel, D.I.1991Evidence for dilution of deep,confined, ground water by vertical recharge of isotopically heavy Pleistocene water.Geology19,no.5:433–436. Sonntag,C.,E.Klitzsch,E.P.Lohnert,E.M.El-shazli,K.O.Munnich,Ch.Junghans,U.Thorweihe,K.Weistoffer,andF.M.Swailem.1979.Palaeoclimatic information from deu-terium and oxygen-18in carbon-14dated North Saharan groundwaters.In Isotope Hydrology1978,vol.2,569–581.Vienna,Austria:IAEA.Tamers,M.A.1975.Validity of radiocarbon dates on ground water.Geophysical Survey,no.2:217–239.V ogel,J.C.1993.Variability of carbon isotope fractionation during photosynthesis.In Stable Isotopes and Plant Carbon-Water Relations,ed.J.R.Ehleringer, A.E.Hall, and G.D.Farquhar,29–38.San Diego,California:Aca-demic Press.V ogel,J.C.1970.Carbon-14dating of ground water.In Isotope Hydrology1970,STI/PUB/255,225–239.Vienna,Austria: IAEA.Wood,W.W.,and W.E.Sanford.1995.Chemical and isotopic methods for quantifying ground water recharge in a regional, semiarid environment.Ground Water,no.3:458–468. Wu,C.1992.The Environmental Evolution During the Last40 ka B.P.in the North China Plain.Beijing,China:Press of Science and technology.Zhang,H.P.,E.K.Liu,D.S.Wang,Y.K.Jia,and J.C.Sun.1991.Composition of stable isotopes of precipitation and control-ling factors in China.Bulletin of the Institute of Hydro-geology and Engineering Geology,Chinese Academy of Geological Sciences7,no.1:101–110.Zhang,J.C.1991.Climate in China.Beijing,China:China Meteorological Press.Zhang,Z.G.,H.P.Zhang,J.C.Sun,L.J.Yang,Y.L.Cui,L.H.Wu,J.X.Qi,and J.M.Xu.1987.Environmental isotope study related to ground water age,flow system and saline water origin in Quaternary aquifer of Hebei plain.Hydro-geology and Engineering Geology96,no.4:1–6. Zhang,Z.H.,Z.L.Shen,Y.Q.Xue,F.H.Ren,D.H.Shi,Z.Z.Yin, Z.X.Zhong,and X.H.Sun.2000.Evolution of Ground Water Environment in the North China Plain.Beijing, China:Geological Publish House.Zheng,S.H.,F.G.Hou,and B.L.Ni.1983.The study of oxygen and hydrogen stable isotope in meteoric water in China.Chinese Science Bulletin,no.13:801–806.C.Zongyu et al.GROUND WATER43,no.4:485–493493。

扬子陆核古元古代晚期构造热事件与扬子克拉通演化

2343扬子陆核古元古代晚期构造热事件与扬子克拉通演化凌文黎高山张本仁周炼徐启东(中国地质大学地球科学学院, 武汉430074.Email:**************.cn)摘要对扬子克拉通太古宙高级区域变质岩系变质事件进行了Sm-Nd 同位素定年(1939~1958 Ma), 综合区内同类岩石的SHRIMP 锆石U-Pb 等相关年龄数据和地质事件, 确认这一时期构造热事件的存在并对其地质意义进行了解析. 通过与扬子克拉通其他地区早期基底岩系形成时代的对比分析, 表明古元古代晚期在整个扬子克拉通范围内存在一次重要的构造热事件, 并导致了扬子陆块统一基底的形成.关键词崆岭高级区构造热事件古元古代统一基底扬子克拉通是我国东部大陆重要的组成陆块之一, 了解其早期的形成与构造演化对充分认识中国大陆地壳的组成长英质TTG岩类主量和微量元素特征, 选取了两个具代表性的样品作为区内斜长角闪岩和副片麻岩的典型代表, 并从中分离出单矿物, 进行Sm-Nd 法内部等时线年龄测定, 以期确定其变质作用发生的时间.斜长角闪岩样品KH35采于崆岭黄凉河剖面, 岩石呈深灰色, 致密块状构造. 显微镜下造岩矿物角闪石和斜长石与石榴石呈镶嵌状花岗变晶结构, 并略具定向. 各矿物颗粒均具较完好晶形, 斜长石和角闪石也基本未见蚀变现象. 矿物组成(体积比)为: 角闪石约54(0.3~0.4mm)(0.075~0.375 mm)和少量以磁铁矿为主2344的不透明矿物. 部分石榴石中含有以斜长石和石英为主的细小包裹体.KH05采于同一剖面, 为副变质长英质岩, 灰白色花岗(-鳞片)变晶结构和片麻状构造. 造岩矿物结晶粒度较KH35粗大, 可能与变质过程中的重结晶作用有关. 矿物组成为: 石英约52%(0.5~2 mm)黑云母约2%~3(0.2~0.4 mm)和少量磁铁矿等不透明矿物. 石榴石嵌于长石和石英颗粒间, 晶形较完整. 斜长石多发生一定程度的绢云母化.样品岩石化学和REE 含量分析由湖北省地质矿产局岩矿分析测试中心完成, 分析方法与质量参见文献[4].Sm-Nd同位素分析由国土资源部壳幔体系组成图1 崆岭变质岩石KH05和KH35样品REE配分曲线2345表2 样品KH05和KH35稀土元素组成(µg/g)样号La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu ∑REEKH0558.610911.441.5 6.82 1.03 6.060.78 3.910.69 1.940.29 2.050.30244.4KH3516.734.54.1717.03.681.334.240.704.480.942.620.422.440.3293.543 Sm-Nd 同位素年龄样品KH05和KH35全岩及单矿物Sm-Nd 同位素测定结果列于表3. 对其中石榴石和斜长石单矿物进行了重复分析, 以检查数据的可信性. 两样品矿物-全岩内部等时线年龄(采用ISOPLOT 软件[5]计算)示于图2.表3 KH05和KH35及其单矿物Sm-Nd 同位素组成a)样号样品143Nd/144Nd2σm 147Sm/144Nd Nd/µg g −1t DM /Ga b)t 2DM /Ga c)KH05-W 片麻岩0.511 288 6 × 10−60.108 7(0.109 4)44.34(44.17)7.978(7.998) 2.692.712.792.77KH05-Gt 石榴石0.512 416(0.512 410)15 × 10−618 × 10−60.196 0 3.518 1.140KH05-Pl 长石0.510 802(0.510 814)12 × 10−616 × 10−60.069 39.236 1.058KH35-W 斜长角闪岩0.512 0029 × 10−60.152 515.21 3.838 2.84 2.52KH35-Pl 长石0.511 334(0.511 349)17 × 10−623 × 10−60.101 5 4.8120.808 0KH35-Gt 石榴石0.517 879(0.517 887)16 × 10−619 × 10−60.609 8 1.099 1.108KH35-Hb角闪石0.512 158(0.512 149)9 × 10−611 × 10−60.151 518.574.656a)括号内数据为重复测定结果; b)采用DMM εNd (0) = +10(143Nd/144Nd = 0.513 15, 147Sm/144Nd = 0.213 7) 的线性演化模式计算; c) 二阶段亏损地幔模式年龄, 其中地壳147Sm/144Nd = 0.118, t = 1.95 Ga副片麻岩(KH05)由全岩石榴石和斜长石组成的等时线年龄为(1958 ± 15) Ma, εNd (t )为−1.5, 等时线也具有很好的线性(MSWD =1.46), 但当回归等时线包括角闪石单矿物时, 等时线年龄值误差增大, 即(1944 ±250) Ma. 误差增大源于角闪石相对等时线的偏移(MSWD=61.6),可能与作为含水矿物的角图2 斜长角闪岩(KH35)与副片麻岩(KH05)Sm-Nd 内部等时线W:全岩; Gt:石榴石; Pl:斜长石; Hb:角闪石2346闪石的Sm-Nd 同位素体系后变质期有一定程度的开放有关.从统计学角度, 崆岭高级变质区斜长角闪岩和副片麻岩的内部等时线年龄谐合一致, 说明区内岩石于约1 950 Ma 共同经历了一次构造热变质事件.4 讨论对于同位素年代学定年数据的检验通常有两种途径晋宁运动ｇ−1Nd/µg2347约2 000 Ma, 并在约1 850 Ma 基本结束.K-Ar 年龄应代表了基底岩系峰期变质后K-Ar 同位素体系冷却封闭的时间, 并以钾长质花岗岩大型岩基的侵入标志构造岩浆事件的结束. 在这一事件过程中, 可能形成了部分初生地壳物质, 并具有较深的侵位, 其存在通过如黄陵花岗岩于晋宁期的地壳深熔作用揭示出来.崆岭地区是目前惟一得到同位素年代学充分证实的扬子克拉通太古宙基底出露地区, 而广泛的扬子克拉通其他地区基底岩系的主要形成时代却为古元古代[11]: 据对244件扬子克拉通不同岩类样品的Sm-Nd 同位素数据统计[12], 其t DM 模式年龄(按现代亏损地幔εNd = +10的线性演化计算)频数峰值位于1.6~2.0 Ga. Li 等人[13]在对扬子克拉通南缘新元古代中期~震旦纪早期的细粒沉积岩做Sm-Nd 同位素分析时发现, 随着大量初生地壳物质的加入, 沉积岩t DM 模式年龄从约1.8 Ga 下降至约1.3 Ga,表明了该地区基底岩系的主要形成时代物质交换及动力学开放研究实验室资助项目.参考文献1凌文黎, 高山, 郑海飞, 等. 扬子克拉通黄陵地区崆岭杂岩Sm-Nd 同位素地质年代学研究扬子克拉通23484 Ling W L, Gao S, Cheng J P, et al. Geochmical characteristic of the Archean high-grad Terrain of the Kongling complex and early crustal evolution of the Yangtze craton. Journal of China University of Geosciences, 1998, 9(2): 100~1085 Ludwig R K. ISOPLOTA Plotting and Regression Program for Radiogenic-isotope Data, Version 2.96. Revision of U SGeological Survey Open File Report 91-445, 1998. 1~496Gao S, Ling W L, Qiu Y , et al. Contrasting geochemical and Sm-Nd isotopic compositions of Archearn metal sediments from the Kongling high-grade terrain of the Yangtze Craton: Evidence for cratonic evolution and redistribution of REE during crustal anatexis. Geochim Cosmochim Acta, 1999, 63(13): 2071~20887 姜继圣. 黄陵变质地区的同位素地质年代及地壳演化. 长春地质学院学报, 1987, (3): 1~118 富公勤. 黄陵断隆北部太古界花岗岩-绿岩地体的发现. 岩石矿物, 1993, (1): 5~139 中国地质年表工作组. 中国地质年表. 北京: 地质出版社, 1987. 14810 冯定犹, 李志晶, 张自超. 黄陵花岗岩类岩基南部岩体侵入时代和同位素特征. 湖北地质, 1991, 5(2): 1~1211 Wang H, Qiao X. Proterozoic stratigraphy and tectonic framework of China. Geol Mag, 1984, 121: 599~61412 陆松年, 杨春亮, 蒋明媚, 等. 前寒武纪大陆地壳演化示踪. 北京: 地质出版社, 1996. 15613Li X H, McCulloch M T. Secular variations in the Nd isotopic composition of Late Proterozoic sediments from the southern margin of the Yangtze Block: Evidence for a Proterozoic continental collision in SE China. Precambrian Res, 1996, 76:67~7614 陈江峰, 周泰禧, 邢凤鸣. 皖南浅变质岩和沉积岩钕同位素组成及沉积物物源区. 科学通报, 1989, 34(20): 1572~157415 张海祥, 孙大中, 朱炳泉, 等. 赣北元古代变质沉积岩的铅钕同位素特征. 中国区域地质, 2000, 19: 66~7116谢智, 陈江峰, 董树文, 等. 大别造山带浅变质岩的锆石U-Pb 年龄. 地球学报, 1999, 20: 335~340(2000-04-21收稿, 2000-07-07收修改稿)。

地质学报.英文版.

地质学报.英⽂版.2019-06-251.Taxonomy and Stratigraphy of Late Mesozoic Anurans and Urodeles from ChinaWANG Yuan2.Early Permian Conodonts from the Baoshan Block, Western Yunnan, ChinaJI Zhansheng，YAO Jianxin，JIN Xiaochi，YANG Xiangning，WANG Yizhao，Yang Hailin，WU Guichun3.Conodont Biostratigraphy of the Middle Cambrian through Lowermost Ordovician in Hunan, South ChinaDONG Xiping，John E.REPETSKI，Stig M.BERGSTR(O)M4.K-Ar Geochronology of Mesozoic Mafic Dikes in Shandong Province, Eastern China:Implications for Crustal ExtensionLiu Shen，HU Ruizhong，Zhao Junhong，Feng Caixia5.SHRIMP Geochronology of Volcanics of the Zhangjiakou and Yixian Formations, Northern Hebei Province, with a Discussion on the Age of the Xing'anling Group of the Great Hinggan Mountains and Volcanic Strata of the Southeastern Coastal Area of ChinaNIU Baogui，HE Zhengjun，SONG Biao，REN Jishun，Xiao Liwei6.Panorama of the Opening-Closing Tectonics Theory in ChinaYang Weiran，ZHENG Jiandong7.Characteristics and Tectonic Significance of the Gravity Field in South ChinaYAN Yafen，Wang Guangjie，ZHANG Zhongjie8.Surplus Space Method:A New Numerical Model for Prediction of Shallow-seated Magmatic BodiesDENG Jun，Huang Dinghua，Wang Qingfei，WAN Li，YAO Lingqing，GAO Bangfei，Liu Yan9.An Inverse Analysis of the Comprehensive Medium Parameters and a Simulation of the Crustal Deformation of the Qinghai-Tibet PlateauYang Zhiqiang，Chen Jianbing，JU Tianyi，LI Tianwen10.A Simple Monte Carlo Method for Locating the Three-dimensional Critical Slip Surface of a SlopeXIE Mowen11.Geochemistry of Ore Fluids and Rb-Sr Isotopic Dating for the Wulong Gold Deposit in Liaoning, ChinaWEI Junhao，QIU Xiaoping，GUO Dazhao，Tan Wenjuan12.Distribution Characteristics of Effective Source Rocks and Their Control on Hydrocarbon Accumulation:A Case Study from the Dongying Sag, Eastern ChinaZhu Guangyou，JIN Qiang，ZHANG Shuichang，Dai Jinxing，Zhang Linye，LI Jian13.Speleogenesis of Selected Caves beneath the Lunan Shilin and Caves of Fenglin Karst in Qiubei, YunnanStanka (S)EBELA，Tadej SLABE，LIU Hong，Petr PRUNER14.Abstracts of Acta Geologica Sinica (Chinese edition) Vol.78, No.6, 200415.Contents of Acta Geologica Sinica Vol.78, Nos.1-6, 20041.New Data of Phosphatized Acritarchs from the Ediacaran Doushantuo Formation at Weng'an, Guizhou Province, Southwest China2.A New Genus of Fossil Cycads Yixianophyllum gen. nov. from the Late Jurassic Yixian Formation, Western Liaoning, China3.On a New Genus of Basal Neoceratopsian Dinosaur from the Early Cretaceous of Gansu Province, China4.A Preliminary Study on the Red Beds in the Northern Heyuan Basin, Guangdong Province, China5.Field Relationships, Geochemistry, Zircon Ages and Evolution of a Late Archaean to Palaeoproterozoic Lower Crustal Section in the Hengshan Terrain of Northern China6.Relationships between Basic and Silicic Magmatism in Continental Rift Settings: A Petrogeochemical Study of Carboniferous Post-collisional Rift Silicic Volcanics in Tianshan, NW China7.SHRIMP Age of Exotic Zircons in the Mengyin Kimberlite, Shandong, and Their Formation8.Jurassic Intra-plate Basaltic Magmatism in Southeast China: Evidence from Geological and Geochemical Characteristics of the Chebu Gabbroite in Southern Jiangxi Provincete Paleozoic Fluid Systems and Their Ore-forming Effects in the Yuebei Basin, Northern Guangdong, China10.Origin and Distribution of Groundwater Chemical Fields of the Oilfield in the Songliao Basin, NE China11.Origins of High H2S-bearing Natural Gas in China12.Abstracts of Acta Geologica Sinica (Chinese Edition) Vol. 79, No. 5, 200513.GUIDANCE FOR CONTRIBUTORS1.A New Ceratopsian from the Upper Jurassic Houcheng Formation of Hebei, ChinaZHAO Xijin，CHENG Zhengwu，XU Xing，Peter J. 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ZHOU Yuefei，WANG Rucheng，LU Jianjun，LI Yiliang18.Abstracts of Acta Geologica Sinica (Chinese Edition) Vol. 80, No. 7, 200619.Abstracts of Acta Geologica Sinica (Chinese Edition) Vol. 80, No. 8, 200620.GUIDANCE FOR CONTRIBUTORS1.Jinfengopteryx Compared to Archaeopteryx, with Comments on the Mosaic Evolution of Long-tailed Avialan BirdsJIShu'an，JI Qiang2.New Nodosaurid Dinosaur from the Late Cretaceous of Lishui, Zhejiang Province, ChinaL(U) Junchang，JIN Xingsheng，SHENG Yiming，LI Yihong，WANG Guoping，Yoichi AZUMA3.The First Stegosaur (Dinosauria, Ornithischia) from the Upper Jurassic Shishugou Formation of Xinjiang, ChinaJIA Chengkai，Catherine A. FOSTER，XU Xing，James M. 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REVERDATTO9.Early Indosinian Weiya Gabbro in Eastern Tianshan, China: Elemental and Sr-Nd-O Isotopic Geochemistry, and Its Tectonic ImplicationsZHANG Zunzhong，GU Lianxing，WU Changzhi，ZHAI Jianping，LI Weiqiang，TANG Junhua10.Diagenesis and Fluid Flow History in Sandstones of the Upper Permian Black Jack Formation, Gunnedah Basin, Eastern AustraliaBAI Guoping，John B. KEENE11.REE Geochemistry of Sulfides from the Huize Zn-Pb Ore Field, Yunnan Province: Implication for the Sources of Ore-forming MetalsLI Wenbo，HUANG Zhilong，QI Liang12.In, Sn, Pb and Zn Contents and Their Relationships in Ore-forming Fluids from Some In-rich and In-poor Deposits in ChinaZHANG Qian，ZHU Xiaoqing，HE Yuliang，ZHU Zhaohui13.Burial Records of Reactive Iron in Cretaceous Black Shales and Oceanic Red Beds from Southern TibetHUANG Yongjian，WANG Chengshan，HU Xiumian，CHEN Xi14.Modes of Occurrence and Geological Origin of Beryllium in Coals from the Pu'an Coalfield, Guizhou, Southwest ChinaYANG Jianye15.40Ar/39Ar Dating of the Shaxi Porphyry Cu-Au Deposit in the Southern Tan-Lu Fault Zone, Anhui ProvinceYANG Xiaoyong，ZHENG Yongfei，XIAO Yilin，DU Jianguo，SUN Weidong16.Carbonate Sequence Stratigraphy of a Back-Arc Basin: A Case Study of the Qom Formation in the Kashan Area, Central IranXU Guoqiang，ZHANG Shaonan，LI Zhongdong，SONG Lailiang，LIU Huimin17.Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, ChinaGAN Huajun，XIAO Xianming，LU Yongchao，JIN Yongbin，TIAN Hui，LIU Dehan18.Occurrences of Excess 40Ar in Hydrothermal Tourmaline:Interpretations from 40Ar-39Ar Dating Results by Stepwise HeatingQIU Huaning，PU Zhiping，DAI Tongmo19.Removal of Cadmium Ions from Aqueous Solution by Silicate-incorporated HydroxyapatiteSHI Hebin，ZHONG Hong，LIU Yu，DENG Jinyang20.GUIDANCE FOR CONTRIBUTORS1.A New Titanosauriform Sauropod from the Early Late Cretaceous of Dongyang, Zhejiang ProvinceL(U) Junchang，Yoichi AZUMA，CHEN Rongjun，ZHENG Wenjie，JIN Xingsheng2.New Fossil Beetles of the Family Elateridae from the Jehol Biota of China (Coleoptera: Polyphaga)CHANG Huali，REN Dong3.New Record of Palaeoscolecids from the Early Cambrian of Yunnan, ChinaHU Shixue，LI Yong，LUO Huilin，FU Xiaoping，YOU Ting，PANG Jiyuan，LIU Qi，Michael STEINER4.Three New Stoneflies (Insecta: Plecoptera) from the Yixian Formation of Liaoning, ChinaLIU Yushuang，RENDong，Nina D. SINITSHENKOVA，SHIH Chungkun5.Annelid from the Neoproterozoic Doushantuo Formation in Northeastern Guizhou, ChinaWANG Yue，WANG Xunlian6.A New Female Cone, Araucaria beipoiaoensis sp. nov. from the Middle Jurassic Tiaojishan Formation, Beipiao, Western Liaoning, China and Its Evolutionary SignificanceZHENG Shaolin，ZHANG Lidong，ZHANG Wu，YANG Yajun7.The Most Complete Pistosauroid Skeleton from the Triassic of Yunnan, ChinaZHAO Lijun，Tamaki SATO，LI Chun8.Chitinozoans from the Fenxiang Formation (Early Ordovician) of Yichang, Hubei Province, ChinaCHENXiaohong，Florentin PARIS，ZHANG Miao9.Sedimentary Features and Implications for the Precambrian Non-stromatolitic Carbonate Succession: A Case Study of the Mesoproterozoic Gaoyuzhuang Formation at the Qiangou Section in Yanqing County of BeijingMEI Mingxiang10.Jurassic Tectonics of North China: A Synthetic ViewZHANG Yueqiao，DONG Shuwen，ZHAO Yue，ZHANG Tian11.Thick-skinned Contractional Salt Structures in the Kuqa Depression, the Northern Tarim Basin: Constraints from Physical ExperimentsYU Yixin，TANG Liangjie，YANG Wenjing，JIN Wenzheng，PENG Gengxin，LEI Ganglin12.Jurassic Tectonic Revolution in China and New Interpretation of the "Yanshan Movement"DONG Shuwen，ZHANG Yueqiao，LONG Changxing，YANG Zhenyu，JI Qiang，WANG Tao，HU Jianming，CHEN Xuanhuate Mesozoic Thermotectonic Evolution of the Jueluotage Range,Eastern Xinjiang, Northwest China: Evidence from Apatite Fission Track DataZHU Wenbin，WAN Jinglin，SHU Liangshu，ZHANG Zhiyong，SU Jinbao，SUN Yan，GUO Jichun，ZHANG Xueyun14.Basin-and Mountain-Building Dynamic Model of "Ramping-Detachment-Compression" in the West Kunlun-Southern Tarim Basin MarginCUI Junwen，LI Pengwu，GUO Xianpu，DING Xiaozhong，TANG Zhemin15.High Pressure Response of Rutile Polymorphs and Its Significance for Indicating the Subduction Depth of Continental CrustMENG Dawei，WU Xiuling，FAN Xiaoyu，ZHANG Zhengjie，CHEN Hong，MENG Xin，ZHENG Jianping HtTp:// 16.Exsolutions of Diopside and Magnetite in Olivine from Mantle Dunite, Luobusa Ophiolite, Tibet, ChinaRENYufeng，CHEN Fangyuan，YANG Jingsui，GAO Yuanhong17.SAED and HRTEM Investigation of PalygorskiteCHEN Tao，WANG Hejing，ZHANG Xiaoping，ZHENG Nan18.Petrologic and REE Geochemical Characters of Burnt RocksHUANG Lei，LIU Chiyang，YANG Lei，ZHAO Junfeng，FANG Jianjun19.Precise Dating and Geological Significance of the Caledonian Shangyou Pluton in South Jiangxi ProvinceMAO Jianren，ZENG Qingtao，LI Zilong，HU Qing，ZHAO Xilin，YE Haimin20.SHRIMP U-Pb Zircon Dating of the Tula Granite Pluton on the South Side of the Altun Fault and Its Geological ImplicationsWU Suoping，WU Cailai，WANG Meiying，CHEN Qilong，Joseph L. WOODEN21.Geochemistry and SHRIMP Zircon U-Pb Age of Post-Collisional Granites in the Southwest Tianshan Orogenic Belt of China: Examples from the Heiyingshan and Laohutai PlutonsLONG Lingli，GAO Jun，WANG Jingbin，QIANQing，XIONG Xianming，WANG Yuwang，WANG Lijuan，GAO Liming22.Zircon LA-ICP MS U-Pb Age, Sr-Nd-Pb Isotopic Compositions and Geochemistry of the Triassic Post-collisional Wulong Adakitic Granodiorite in the South Qinling, Central China, and Its PetrogenesisQIN Jiangfeng，LAI Shaocong，WANG Juan，LI Yongfei23.Estimating Influence of Crystallizing Latent Heat on Cooling-Crystallizing Process of a Granitic Melt and Its Geological ImplicationsZHANG Bangtong，WU Junqi，LING Hongfei，CHEN Peirong24.Archean Mass-independent Fractionation of Sulfur Isotope:New Evidence of Bedded Sulfide Deposits in the Yanlingguan-Shihezhuang area of Xintai, Shandong ProvinceLI Yanhe，HOU Kejun，WAN Defang，YUE Guoliang 25.Geochemical Mapping: With Special Emphasis on Analytical RequirementsXIE Xuejing，CHENG Hangxin，LIU Dawen1.A Baby Pterodactyloid Pterosaur from the Yixian Formation of Ningcheng, Inner Mongolia, ChinaL(U) Junchang2.A New Theropod Dinosaur from the Middle Jurassic of Lufeng, Yunnan, ChinaWU Xiao-chun，Philip J.CURRIE，DONG Zhiming，PAN Shigang，WANG Tao3.Aerodynamic Characteristics of the Crest with Membrane Attachment on Cretaceous Pterodactyloid NyctosaurusXING Lida，WU Jianghao，LU Yi，L(U) Junchang，JI Qiang4.New Fossil Palaeontinids from the Middle Jurassic of Daohugou, Inner Mongolia, China(Insecta, Hemiptera)WANG Ying，REN Dong5.Evolution of Dentary Diastema in Iguanodontian DinosaursKatsuhiro KUBOTA，Yoshitsugu KOBAYASHI6.Revision of the Clam Shrimp Genus Magumbonia from the Upper Jurassic of the Luanping Basin,Hebei,Northern ChinaLI Gang，SHEN Yanbin，LIU Yongqing，Peter BENGTSON，Helmut WILLEMS，Hiramichi HIRAN07.Yarlongite:A New Metallic Carbide MineralSHI Nicheng，BAI Wenji，LI Guowu，XIONG Ming，FANG Qingsong，YANG Jingsui，MA Zhesheng，RONG He8.Phase Equilibria of Hornblende-Bearing Eclogite in the Western Dabie Mountain,Central ChinaZHANG Jingsen，WEI Chunjing，LOU Yuxing，SU Xiangli9.Diagenesis and Evolution of the Holocene Coquinite from the Haishan Island,Eastern Guangdong,ChinaSUNJinlong，XU Huilong，QIU Xuelin，ZHAN Wenhuan，LI Yamin10.Structural Characteristics and Formation Mechanism in the Micangshan Foreland,South ChinaXU Huaming，LIU Shu，QU Guosheng，LI Yanfeng，SUN Gang，LIU Kang11.Tectonic Evolution of the Middle Frontal Area of the Longmen Mountain Thrust Belt, Western Sichuan Basin, ChinaJIN Wenzheng，TANG Liangjie，YANG Keming，WAN Guimei，L(U) ZhiZhou，YU Yixinx12.Oxygen and Hydrogen Isotopes of Waters in the Ordos Basin,China: Implications for Recharge of Groundwater in the North of Cretaceous Groundwater BasinYANG Yuncheng，SHEN Zhaoli，WENG Dongguang，HOU Guangcai，ZHAO Zhenhong，WANG Dong，PANG Zhonghe13.Variations of Microbial Communities and the Contents and Isotopic Compositions of Total Organic Carbon and Total Nitrogen in Soil Samples during Their PreservationTAO Qianye，LI Yumei，WANG Guo'an，QIAO Yuhui，LIU Tung-Sheng14.Tectonic Landform of Quaternary Lakes and Its Implications for Deformation in the Northern Qinghai-Tibet PlateauWANG An，WANG Guocan，LI Dewei，XIE Defan，LIU Demin15.A Climatic Sequence Stratigraphic Model in the Terrestrial Lacustrine Basin:A Case Study of Green River Formation,Uinta Basin,USAWANG Junling，ZHENG Herong，XIAO Huanqin，ZHONG Guohong，Ronald STEEL，YIN Peigui16.Accumulation Mechanisms and Evolution History of the Giant Puguang Gas Field, Sichuan Basin, ChinaHAOFang，GUO Tonglou，DU Chunguo，ZOU Huayao，CAI Xunyu，ZHU Yangming，LI Pingping，WANGChunwu，ZHANG Yuanchun17.Origin and Accumulation of Natural Gases in the Upper Paleozoic Strata of the Ordos Basin in Central ChinaZHU Yangming，WANG Jibao，LIU Xinse，ZHANG Wenzheng18.Differential Tectonic Deformation of the Longmen Mountain Thrust Belt,Western Sichuan Basin,ChinaTANG Liangjie，YANG Keming，JIN Wenzheng，WAN Guime，L(U) Zhizhou，YU Yixin19.Tectonic Framework and Deep Structure of South China and Their Constraint to Oil-Gas Field DistributionWANG Qingchen，LIU Jinsong，DU Zhili，CAI Liguorge-scale Tazhong Ordovician Reef-fiat Oil-Gas Field in the Tarim Basin of ChinaZHOU Xinyuan，WANG Zhaoming，YANG Haijun，ZHANG Lijuan，HAN Jianfa，WANG Zhenyu注：本⽂为⽹友上传，不代表本站观点，与本站⽴场⽆关。

恐龙迁徙英文作文

恐龙迁徙英文作文Title: The Migration of Dinosaurs。

Introduction:Dinosaurs, the ancient giants that once roamed the Earth, captivate our imagination with their sheer size and mysterious extinction. One of the fascinating aspects of these creatures is their migration patterns. In this essay, we delve into the phenomenon of dinosaur migration, exploring its significance, possible reasons, and the evidence supporting it.Significance of Dinosaur Migration:Migration is a common phenomenon observed in various animal species, serving crucial ecological and survival purposes. Similarly, dinosaurs, despite their dominance over terrestrial ecosystems, were not exempt from migratory behavior. Understanding their migration patterns providesvaluable insights into their biology, ecology, and interactions with the environment.Evidence of Dinosaur Migration:Evidence of dinosaur migration primarily comes fromfossil records and geological studies. Fossilized trackways, particularly those found in sedimentary rocks, offer compelling evidence of large-scale movement patterns. For example, the discovery of extensive trackways in regionslike the Western Interior Seaway in North America suggests long-distance migrations by certain dinosaur species.Additionally, isotopic analysis of dinosaur bones and teeth provides clues about their dietary habits and geographic movements. Variations in isotopic signatures across different regions indicate shifts in habitat and migration between distinct ecosystems.Reasons for Dinosaur Migration:Several factors likely influenced dinosaur migration,including changes in climate, food availability, reproductive behavior, and the need to avoid predators. Seasonal migrations might have occurred in response to fluctuations in temperature and vegetation, with dinosaurs moving to more favorable habitats during harsh winters or dry seasons.Furthermore, the search for breeding grounds and nesting sites could have driven migratory behavior in certain species. Coastal regions or riverbanks might have served as preferred nesting sites for dinosaurs, prompting seasonal migrations to these areas for reproduction.Migration Routes and Patterns:Determining the specific routes and patterns of dinosaur migration poses challenges due to the scarcity of direct evidence. However, geological and paleontological studies provide some insights into potential migration routes based on fossil distributions and landscape reconstructions.For instance, the presence of similar dinosaur species across different continents suggests the existence of land bridges or connections between landmasses during the Mesozoic era. These land bridges facilitated the exchangeof fauna between continents, leading to intercontinental migrations of dinosaurs.Implications for Dinosaur Ecology and Evolution:Studying dinosaur migration enriches our understandingof their ecological roles and evolutionary strategies. Migration likely played a crucial role in dispersingspecies across vast geographical areas, shapingbiodiversity patterns and ecosystem dynamics over millionsof years.Furthermore, migration may have influenced evolutionary processes, such as speciation and adaptation to new environments. By exploring the relationship betweenmigration and evolutionary change, scientists can gain insights into the long-term resilience of dinosaur populations and their responses to environmental challenges.Conclusion:In conclusion, the migration of dinosaurs represents a fascinating aspect of their biology and behavior. Through fossil evidence, isotopic analysis, and geological studies, scientists continue to unravel the mysteries surrounding dinosaur migration patterns. By understanding the drivers and implications of migration, we gain deeper insights into the lives of these ancient creatures and the dynamic nature of prehistoric ecosystems.。

四川丹巴县独狼沟金矿床成因：来自同位素证据

第59卷第3期2023年5月地质与勘探GEOLOGY AND EXPLORATIONVol.59No.3May，2023四川丹巴县独狼沟金矿床成因：来自同位素证据凡韬1，2，3，王春林1，2，3，杨波1，2，蔺吉庆1，3，王毅1，杨开均1，张超1（1.四川省第七地质大队，四川乐山614000；2.四川省深地资源勘查开发研究院，四川乐山614200；3.张建东劳模创新工作室，四川乐山614200）［摘要］四川丹巴县独狼沟金矿床是扬子陆块西缘金成矿带上的一个大型金矿床。

矿体呈较高品位、较厚单体石英脉充填于构造破碎带之间，呈透镜状、似层状和层状产出，受断层构造影响极为明显，具热液矿床特征。

矿物学、锆石U-Pb测年成果和稀土元素及微量元素等方面研究显示矿床主要受两期热液成矿作用影响，早期热液成矿作用形成以磁黄铁矿、黄铁矿等高温热液矿物为主的金矿体，时限限定于184.2±1.1Ma；晚期热液成矿作用则形成以黄铜矿、叶碲铋矿等中温热液矿物为主的金矿体，时限限定于156.5±4.3Ma。

成矿流体氢氧同位素组成表明其与该时期区域岩浆作用存在一定关联而与区域变质作用关系不密切。

S同位素组成反映出其来源为深部来源的属性，在Pb同位素组成的研究中也对这一观点进行了验证。

成矿流体被认为是来自交代岩石圈地幔，在早侏罗世软流圈上涌事件影响下交代岩石圈地幔中挥发分上涌并活化上覆地层中的金，从而形成富金成矿流体并沿区域性深大断裂上移就位于地壳岩石地层中成矿。

成矿动力学机制与区域碰撞造山后由挤压向伸展转换的大地构造背景密切关联，认为独狼沟金矿床为典型造山型金矿床。

［关键词］U-Pb锆石年代学岩石化学同位素地球化学矿床成因独狼沟金矿丹巴县四川省［中图分类号］P618.51［文献标识码］A［文章编号］0495-5331（2023）03-0481-16Fan Tao,Wang Chunlin,Yang Bo,Lin Jiqing,Wang Yi,Yang Kaijun,Zhang Chao.Genesis of the Dulanggou gold deposit in Danba County of Sichuan Province:Based on isotopic evidence[J].Geology and Exploration,2023,59(3):0481-0496.0前言国外学者研究认为造山型金矿是与增生造山作用或碰撞造山作用密切相关的一种热液型金矿床，大多沿活动大陆边缘带分布（Goldfarb andGroves，2015；Bierlein and Crowe，2000），其形成于造山作用后的转换挤压构造环境或伸展构造环境的区域变质岩地层中，产于汇聚板块边界上受韧脆性断裂控制的脉状或浸染状金矿床（Groves et al.，1998）。

Secular change in earth processes

EditorialSecular change in earth processes:Preface1.IntroductionUniformitarianism is a traditional approach used in many areas of geoscience that assumes the geologic processes observed today operated similarly throughout all of Earth history(Hutton,1788; Windley,1993),with such an ideology commonly encapsulated by the maxim“the present is the key to the past”.This concept is closely associated with the philosophical principle of Occam’s razor, as discussed by Gould(1987)in his critique of its usage in the nat-ural sciences:“we should try to explain the past by causes now in operation without inventing extra,fancy,or unknown causes,however plausible in logic,if available processes sufﬁce”.Nonetheless, although the spatio-temporal constancy of many natural phenom-ena(e.g.the rate of decay of radiogenic nuclides)appears to pro-mote direct comparison of the modern-day Earth with that of the past,the rock record preserves a wide range of petrological,struc-tural,geochemical,and isotopic evidence for signiﬁcant changes in earth-system processes and products over geological time.While some of these physio-chemical changes are thought to have occurred gradually,such as secular cooling of the Earth’s mantle(Herzberg et al.,2010),others likely took place over much shorter timescales,such as a rapid rise in the partial pressure of atmospheric O2at ca.2.3Ga(the Great Oxidation Event:Bekker et al.,2004).Such changes in ambient conditions may have signif-icant effects on the geological products that are preserved in the rock record,which has implications for interpretation of past tec-tonic regimes.How and why these processes have changed over time is important as they affect the mechanisms of growth and reworking of the continental crust(Hawkesworth et al.,2010), contribute to long-term global climate change(Sleep,2010),and control the location and timing of formation of mineral endow-ments necessary to support human ambition in the future (Goldfarb et al.,2010).Furthermore,understanding how plate tec-tonics developed on Earth allows us to gain greater insight into the evolution of other planetary bodies in our solar system and beyond(e.g.Noack and Breuer,2014;Wade et al.,2017).2.Contributions in this special issueThis special issue of Geoscience Frontiers assembles four papers authored primarily by early-career researchers that investigate various aspects of secular change throughout Earth history.These studies shed new light on the veracity of uniformitarianistic methods used to interpret the evolution of the Earth throughout geological time.Theﬁrst study in this Special Issue by Nicoli and Dyck(2018) examines the effects of secular change in the major-element composition of terrigenous sediments on the metamorphic prod-ucts that they may produce during accretionary or collisional orogenesis.Indeed,a number of recent studies have spearheaded a resurgence of interest in secular change in continental crust composition since ca.3.5Ga(e.g.Tang et al.,2016;Greber et al., 2017),which has been an area of research focus for many decades previously(e.g.Condie,1993).In their paper“Exploring the meta-morphic consequences of secular change in the siliciclastic composi-tions of continental margins”,Nicoli and Dyck(2018)applied thermodynamic phase equilibrium modeling to a range of bulk-rock compositions reported in the literature of varying age,from the Archean to the Phanerozoic,and examine the metamorphic rock types and partial melts that would form along classical Barrovian-type geotherms(Barrow,1912).They show that the muscovite dehydration melting has become increasingly important in metamorphosed shales through geological time,and partial melt compositions have become increasingly calcic and less maﬁc.In addition,the potential water budget of continental margins has decreased since the Archean,which has implications for the fertility of continental crust and may account for observed changes in the volume and diversity of orogenic magmas in the geological record(e.g.Ganne et al.,2016;Moyen and Laurent,2017).In the second contribution,Moreira et al.(2018)take a fresh new look at what is colloquially known as the“Siderian Quiet Interval”(ca.2.45e2.20Ga)characterized by a global magmatic lull,when some researchers have even suggested that plate tectonics tempo-rarily shut down altogether(Condie et al.,2009)or subduction zone magmatism had transitioned from continental settings to the lesser preserved ocean realm(Spencer et al.,2018).In this contribution entitled“Evolution of Siderian juvenile crust to Rhyacian high Ba e Sr magmatism in the Mineiro Belt,southern São Francisco Craton”, Moreira et al.(2018)document the results of geochemical and geochronological investigation of a suite of magmatic rocks from the Mineiro Belt,Brazil,that show a compositional transition from TTG to sanukitoids,consistent with the onset of subduction. The timing of initiation of plate tectonics on Earth is a hotly debated topic(e.g.Korenaga,2013,and references therein),and Moreira et al.(2018)provide new data that support a global onset at around the Archean e Proterozoic boundary.Peer-review under responsibility of China University of Geosciences(Beijing).H O S T E D BY Contents lists available at ScienceDirectChina University of Geosciences(Beijing)Geoscience Frontiersjournal homep age:www.elsevie/locate/gsfGeoscience Frontiers9(2018)965e966https:///10.1016/j.gsf.2018.05.0011674-9871/Ó2018,China University of Geosciences(Beijing)and Peking University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(/licenses/by-nc-nd/4.0/).Moving towards a broader-scale tectonic focus,Zhang et al. (2018)present a paper focused on the driving forces of supercon-tinent breakup,which is known to have occurred multiple times throughout geological time(e.g.Bradley,2011;Nance et al.,2014). Following on from the revolutionary paper by Forsyth and Uyeda (1975),where slab pull was shown to be the main driving force of plate tectonic motion on the Earth,Zhang et al.(2018)present theﬁrst study of its kind to quantify the relative contributions of plume push,subduction retreat,and gravitational collapse using global-scale3D geodynamical modeling.In their paper entitled “The dominant driving force for supercontinent breakup:Plume push or subduction retreat?”,they show that plume push is the dominant force that drives supercontinent breakup,and the associated plume-push stress is around three-times greater than that induced by subduction retreat within supercontinent interiors.Such a result has notable implications for our understanding of large-scale lithospheric dynamics and how plate tectonic force balancing has evolved throughout geological time.Finally,in a return to the rock record itself,Palin and Dyck(2018) provide an overview of the causes,consequences,and petrological implications of secular cooling of the mantle over geological time.A hotter Archean mantle is predicted to have produced a signiﬁcantly different structure and composition of primary oceanic crust than is observed today(Herzberg et al.,2010).In particular,subsolidus and suprasolidus phase relations for peridotitic mantle infer that primary oceanic crust as a whole and its uppermost basaltic portion should both be enriched in MgO in the Archean compared to today and depleted in Al2O3(and others;McKenzie and Bickle,1988), with these compositional trends supported by statistical investiga-tion of the volcanic and magmatic rock record(e.g.Keller and Schoene,2012).In their paper entitled“Metamorphic consequences of secular changes in oceanic crust composition and implications for uniformitarianism in the geological record”,Palin and Dyck(2018) examine the effects of this secular change in oceanic crust compo-sition on the metamorphosed products that would form during subduction,and show that many of the rock types observed in the Phanerozoic,which formed from relatively low-MgO maﬁc crust,would not have been stable in Archean or Proterozoic subduction zones.This work has key implications for the use of uni-formitarianistic principles to interpret geological processes and tec-tonic environments in the ancient rock record(e.g.Stern,2005; Palin and White,2016),which has long been a cornerstone of the discipline.We thank all the contributors to this Special Issue,and the referees who spared their valuable time to provide insightful and helpful comments.Dr.Lily Wang,Editorial Assistant at Geoscience Frontiers,and Prof.Santosh,Editorial Advisor,are also thanked for their support throughout the production process.We envisage that the papers assembled herein will be of interest to many researchers interested in the long-term evolution of the Earth.ReferencesBarrow,G.,1912.On the geology of lower dee-side and the southern highland border.Proceedings of the Geologists’Association23,275e290.Bekker,A.,Holland,H.D.,Wang,P.L.,Rumble,D.,Stein,H.J.,Hannah,J.L.,Coetzee,L.L., Beukes,N.J.,2004.Dating the rise of atmospheric oxygen.Nature427,117e120. Bradley,D.C.,2011.Secular trends in the geologic record and the supercontinent cycle.Earth-Science Reviews108,16e33.Condie,K.C.,1993.Chemical composition and evolution of the upper continental crust:contrasting results from surface samples and shales.Chemical Geology 104,1e37.Condie,K.C.,O’Neill,C.,Aster,R.C.,2009.Evidence and implications for a wide-spread magmatic shutdown for250My on Earth.Earth and Planetary Science Letters282,294e298.Forsyth,D.,Uyeda,S.,1975.On the relative importance of the driving forces of plate motion.Geophysical Journal of the Royal Astronomical Society43,163e200. Ganne,J.,Feng,X.,Rey,P.,De Andrade,V.,2016.Statistical petrology reveals a link between supercontinents cycle and mantle global climate.American Mineralo-gist101,2768e2773.Goldfarb,R.J.,Bradley,D.,Leach,D.L.,2010.Secular variation in economic geology.Economic Geology105,459e465.Gould,S.J.,1987.Time’s Arrow,Time’s Cycle:Myths and Metaphor in the Discovery of Geological Time.Harvard University Press,Cambridge,MA.Greber,N.D.,Dauphas,N.,Bekker,A.,Ptá c ek,M.P.,Bindeman,I.N.,Hofmann,A.,2017.Titanium isotopic evidence for felsic crust and plate tectonics3.5billion years ago.Science357,1271e1274.Hawkesworth, C.J.,Dhuime, B.,Pietranik, A.B.,Cawood,P.A.,Kemp, A.I.S., Storey, C.D.,2010.The generation and evolution of the continental crust.Journal of the Geological Society167,229e248.Herzberg,C.,Condie,K.,Korenaga,J.,2010.Thermal history of the Earth and its petrological expression.Earth and Planetary Science Letters292,79e88. Hutton,J.,1788.Theory of the earth;or an investigation of the laws observable in the composition,dissolution,and restoration of land upon the globe.Transac-tions of the Royal Society of Edinburgh1,209e304.Keller,C.B.,Schoene,B.,2012.Statistical geochemistry reveals disruption in secular lithospheric evolution about2.5Gyr ago.Nature485,490e493.Korenaga,J.,2013.Initiation and evolution of plate tectonics on Earth:theories and observations.Annual Review of Earth and Planetary Sciences41,117e151. McKenzie,D.,Bickle,M.J.,1988.The volume and composition of melt generated by extension of the lithosphere.Journal of Petrology29,625e679.Moreira,H.,Seixas,L.,Storey,C.,Fowler,M.,Lasalle,S.,Stevenson,R.,Lana,C.,2018.Evolution of siderian juvenile crust to rhyacian high Ba-Sr magmatism in the Mineiro Belt,southern São Francisco Craton.Geoscience Frontiers9,977e995. Moyen,J.F.,Laurent,O.,2017.Archaean tectonic systems:a view from igneous rocks.Lithos302e303,99e125.Nance,R.D.,Murphy,J.B.,Santosh,M.,2014.The supercontinent cycle:a retrospec-tive essay.Gondwana Research25,4e29.Nicoli,G.,Dyck, B.,2018.Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins.Geoscience Frontiers9,967e975.Noack,L.,Breuer,D.,2014.Plate tectonics on rocky exoplanets:inﬂuence of initial conditions and mantle rheology.Planetary and Space Science98,41e49. Palin,R.M.,Dyck,B.,2018.Metamorphic consequences of secular changes in oceanic crust composition and implications for uniformitarianism in the geological re-cord.Geoscience Frontiers9,1009e1019.Palin,R.M.,White,R.W.,2016.Emergence of blueschists on Earth linked to secular changes in oceanic crust composition.Nature Geoscience9,60e64.Sleep,N.H.,2010.The hadean e archaean environment.Cold Spring Harbor Perspec-tives in Biology2.https:///10.1101/cshperspect.a002527.Spencer,C.J.,Murphy,J.B.,Kirkland,C.L.,Liu,Y.,Mitchell,R.N.,2018.A Palaeoproter-ozoic tectono-magmatic lull as a potential trigger for the supercontinent cycle.Nature Geoscience11,97e101.https:///10.1038/s41561-017-0051-y. Stern,R.J.,2005.Evidence from ophiolites,blueschists,and ultrahigh-pressure metamorphic terranes that the modern episode of subduction tectonics began in Neoproterozoic time.Geology33,557e560.Tang,M.,Chen,K.,Rudnick,R.L.,2016.Archean upper crust transition from maﬁc to felsic marks the onset of plate tectonics.Science351,372e375.Wade,J.,Dyck,B.,Palin,R.M.,Moore,J.D.,Smye,A.J.,2017.The divergent fates of primitive hydrospheric water on Earth and Mars.Nature552,391e395. Windley,B.F.,1993.Uniformitarianism today:plate tectonics is the key to the past.Journal of the Geological Society of London150,7e19.Zhang,N.,Dang,Z.,Huang,C.,Li,Z.-X.,2018.The dominant driving force for super-continent breakup:plume push or subduction retreat?Geoscience Frontiers9, 997e1007.Richard M.Palin* Department of Geology and Geological Engineering,Colorado Schoolof Mines,Golden,CO80401,USAChristopher J.Spencer The Institute of Geoscience Research(TIGeR),School of Earth and Planetary Sciences,Curtin University,WA6102,AustraliaE-mail address:cspencer@.au*Corresponding author.E-mail address:richardmpalin@(R.M.Palin)Available online4May2018Editorial/Geoscience Frontiers9(2018)965e966 966。

ssat听力高分窍门二

ssat听力高分窍门二把握逻辑结构，破解天文学听力文章很多同学都说天文学是听力中最难的，因为不仅抽象，还会出现很多没听说过的专业名词，比如，这篇讲“弱阳吊诡”理论的文章一开头就把大家听晕了，什么paradox，pebble，fossilized algae，hydrogen，helium，stellar evolution这样的专业天文词汇一下子如大波僵尸扑面而来，反应速度着实有点儿跟不上。

那么，要如何应对这样生词多、话题抽象的天文学文章呢？答案是：把握逻辑结构。

只要听时清晰把握逻辑，再听懂几个关键词，马上就可以正确解题，开头1分多钟的内容都是浮云，听懂听不懂其实关系并不大。

Why is geological evidence of liquid water on Earth and Mars three to four billion years ago problematic？A. It suggests that the solar system is younger than it could possibly be.B. It suggests that the young Sun was less bright than it is todayC. It challenges the prevailing model of star formation.D.?It contradicts theories about the beginning of the universe.首先，我们要对题目做“缩句”，去掉一些冗余信息，请看标红的部分：为什么“地质学证据”有问题？好，我们再看对应原文中标红的关键词：Now，this apparent contradiction between geologic evidence and the stellar evolution model became known as the faint young Sun paradox.既然“地质学证据”与“星体进化模型”是“互相矛盾”的，那么，他们就像情敌见面分外眼红一样，彼此都容不得对方的存在。

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ARTICLEGeological and isotopic evidence for magmatic-hydrothermal origin of the Ag –Pb –Zn deposits in the Lengshuikeng District,east-central ChinaChangming Wang &Da Zhang &Ganguo Wu &M.Santosh &Jing Zhang &Yigan Xu &Yaoyao ZhangReceived:7August 2012/Accepted:27March 2014/Published online:8April 2014#Springer-Verlag Berlin Heidelberg 2014Abstract The Lengshuikeng ore district in east-central China has an ore reserve of ∼43Mt with an average grade of 204.53g/t Ag and 4.63%Pb+Zn.Based on contrasting geological characteristics,the mineralization in the Lengshuikeng ore district can be divided into porphyry-hosted and stratabound types.The porphyry-hosted minerali-zation is distributed in and around the Lengshuikeng granite porphyry and shows a distinct alteration zoning including minor chloritization and sericitization in the proximal zone;sericitization,silicification,and carbonatization in the periph-eral zone;and sericitization and carbonatization in the distal zone.The stratabound mineralization occurs in volcano-sedimentary rocks at ∼100–400m depth without obvious zoning of alterations and ore minerals.Porphyry-hosted and stratabound mineralization are both characterized by early-stage pyrite –chalcopyrite –sphalerite,middle-stage acanthite –native silver –galena –sphalerite,and late-stage pyrite –quartz –calcite.The δ34S values of pyrite,sphalerite,and galena in the ores range from −3.8to +6.9‰with an average of +2.0‰.The C –O isotope values of siderite,calcite,and dolomite range from −7.2to −1.5‰with an average of −4.4‰(V-PDB)and from +10.9to +19.5‰with an average of +14.8‰(V-SMOW),respectively.Hydrogen,oxygen,and carbon iso-topes indicate that the hydrothermal fluids were derived main-ly from meteoric water,with addition of minor amounts of magmatic water.Geochronology employing LA –ICP –MS analyses of zircons from a quartz syenite porphyry yielded a weighted mean 206Pb/238U age of 136.3±0.8Ma considered as the emplacement age of the porphyry.Rb –Sr dating of sphalerite from the main ore stage yielded an age of 126.9±7.1Ma,marking the time of mineralization.The Lengshuikeng mineralization classifies as an epithermal Ag –Pb –Zn deposit.Keywords Stable isotope .Geochemistry .Porphyry .Stratabound .Ag –Pb –Zn .LengshuikengIntroductionThe Lengshuikeng ore district,located in the Jiangxi Province of east-central China (Fig.1a ),contains more than 50ore bodies belonging to seven deposits hosted in granite porphyry,pyroclastic,and carbonate rocks.The ore reserves in Lengshuikeng have been estimated at ∼43Mt with average grades of 2.11%Pb,2.61%Zn,204.53g/t Ag,0.08g/t Au,and 0.01%Cd.The ores can be grouped into two types:(1)porphyry-hosted (Yinluling,Baojia,and Yinzhushan)and (2)stratabound (Xiabao,Yinkeng,Yinglin,and Xiaoyuan).The porphyry-hosted mineralization is distributed within and around the Lengshuikeng granite porphyry,whereas the stratabound mineralization occurs in volcano-sedimentary rocks at ∼100–400m depth.The spatial distribution of the porphyry-hosted and stratabound ore bodies,their mineral constituents,and the zoning of alteration assemblages are markedly different from those of typical porphyry deposits.Editorial handling:T.Bissig and G.BeaudoinC.Wang (*):D.Zhang :G.Wu :M.Santosh :J.Zhang :Y .Xu :Y .ZhangState Key Laboratory of Geological Processes and MineralResources,China University of Geosciences,No.29,Xueyuan Road,Beijing 100083,People ’s Republic of China e-mail:wcm233@Y .XuNo.912Geological Surveying Team,Bureau of Geology and Mineral Exploration and Development,Yingtan 334000,ChinaMiner Deposita (2014)49:733–749DOI 10.1007/s00126-014-0521-8Over the past several decades,research in the Lengshuikeng ore district was focused on geological characteristics,mineral-ization,wall rock alteration,fluid inclusions,and geochemistry of the porphyry-hosted deposits (Deng 1991;Meng et al.2007;Wang et al.2010c ).Recently,stratabound Ag –Pb –Zn deposits have been found beneath the porphyry-hosted deposits,occur-ring in volcano-sedimentary rocks of the E ’huling Formation.This paper reports the geologic and isotopic characteristics of the porphyry-hosted and stratabound ores,in combination with those from Chinese literature.The regional and theLengshuikeng Ag –Pb –Zn ore district geologies,including the occurrence of ore bodies,and associated hydrothermal alter-ation are described,followed by a discussion of the origin of the Ag –Pb –Zn deposits.Regional geological settingThe Lengshuikeng ore district is located in northeastern Jiangxi Province,east-central China,close to the Shaoxing–Fig.1a Location map for the Lengshuikeng District.b Sketch map showing the Late Mesozoic volcanic-intrusive complex belt in SE China.c Sketch map showing the regional geology of the Lengshuikeng ore district and Dexing ore field (modified after Jiang et al.2011).Major faults in the study area:Shi –Hang Shiwandashan –Hangzhou as collision-induced suture zone between the Cathaysia and Yangtze blocks,SJ Shaoxing –Jiangshan,ZD Zhenghe –DapuJiangshan(SJ)fault between the Cathaysia and Yangtze blocks(Fig.1b).This fault represents the eastern part of the Shiwandashan–Hangzhou(Shi–Hang)fault zone and is con-sidered to mark the collisional suture zone in SE China(Yao et al.2011).Geophysical and remote sensing data suggest that the SJ fault extends deep into the lower crust and upper mantle (Fig.1c;Wang et al.2010c).The collisional amalgamation of the Cathaysia and Yangtze blocks into the proto“South China”Block(SCB)began in the early Qingbaikou period (∼950±50Ma)and was completed by the end of the Jinning Orogeny at ca.850Ma(Shu and Charvet1996;Charvet et al. 1996;Li et al.2008,2010;Zhang and Zheng2013).During the Sinian(ca.850–600Ma),the Yangtze and Cathaysia blocks were rifted.In the Caledonian(600–405Ma),the Yangtze and Cathaysia blocks collided for a second time and reunited within the SCB(Zhou et al.2002;Wang et al.2010a, b).During the Variscan(405–270Ma),extension within the SCB resulted in Paleozoic intracontinental rifts.The Indosinian collision between the South China and North China blocks occurred from the Palaeozoic to Late Triassic(ca.270–208Ma;Wang et al.2013a,2014a). Magmatic activity during208to180Ma is documented by bimodal magmatism in southeastern Hunan Province and the A-type granitic magmatism in southern Jiangxi Province(Zhao et al.1998;Yu et al.2006,2010).From Triassic to Early Jurassic(180–145Ma),most areas of the Wuyi Mountains in the northeastern part of the Cathaysia Block(Fig.1b)were folded and uplifted before undergoing extensional collapse.The region ex-perienced Early Cretaceous granite magmatism(145–100Ma) and the formation of large-scale Late Cretaceous–Paleogene red bed sedimentary basins between100and70Ma(Jahn 1974;Jahn et al.1990;Zhou et al.2006;Shu et al.2009;Wang et al.2014b).The Precambrian units include greenschist facies metamorphic rocks dated at1,000–800Ma(Fig.1c;Li et al.1996;Shu and Charvet1996;Zhou et al.2002; Shu et al.2009).The Cambrian and Ordovician rocks are mainly sandstone,mudstone,and carbonaceous mudstone. Silurian sedimentary rocks are absent.The Devonian, Carboniferous,and Permian strata comprise shallow marine to littoral facies clastic rocks,limestone,and dolomite.The Lower Triassic series consists of muddy limestone and shale. Middle Triassic strata are absent in most areas of the Wuyi Mountains.The Wuyi Mountains are largely composed of Late Mesozoic volcanic rocks and associated clastic strata (Fig.1c).Lower Jurassic strata include conglomerate and coarse arkosic sandstone,quartz sandstone,and siltstone with carbonaceous mudstone and coal-bed intercalations.Middle Jurassic strata are composed of terrestrial clastic rocks and bimodal volcanic rocks.Upper Jurassic strata comprise andes-ite and rhyolitic tuffs and tuffaceous siltstone(Liu1985;Ye 1987).Lower Cretaceous strata include rhyolitic welded tuffs with basalt intercalations(Yu et al.2006).Upper Cretaceous siltstone and mudstone are intercalated with gypsum-bearing layers and basalt,the latter with an age of105–98Ma(Yu et al.2001).Paleogene strata include coarse clastic rocks,siltstone,and mudstone with inter-calated gypsum and oil-bearing shale.Neogene silt-stones locally overlie the Paleogene rocks.Southeast China is characterized by extensive magmatism, which formed a belt of volcanic-intrusive complexes(Fig.1b). Two major tectono-magmatic periods have been recognized in the Wuyi Mountains:the Indosinian and the Yanshanian.The Indosinian magmatic period lasted from240to208Ma(Xie et al.2006).The Yanshanian igneous rocks formed during two main stages of Early Yanshanian(208–145Ma)and Late Yanshanian(145–90Ma)and are characterized by abundant rhyolitic volcanic rocks and highly aluminous granitoids(Jahn et al.1976;Chen1999;Li2000;Deng et al.2010,2011,2014; Zhou et al.2006;Zhao et al.2012).Geology of the Lengshuikeng ore districtDeposit geologyThe stratigraphic sequence in the Lengshuikeng District com-prises the Jurassic Daguding and E’huling Formations.The Daguding Formation is composed of andesite and rhyolitic tuffs and tuffaceous siltstone.The E’huling Formation is composed of tuffs,rhyolite,tuffaceous siltstone,sandstone, and manganese-and iron-rich carbonates,which are the main host of the stratabound ores.The NE-striking F1fault dipping toward NW(Figs.2and 3a)comprises the northern segment of the Hushi fault.The most prominent structural feature in the Lengshuikeng District is F2reverse fault(Figs.2and3a).The stratabound fracture along the manganese-and iron-rich carbonate strata(Fig.3a) was cemented by later ore sulfide minerals and hydrothermal alteration minerals.Middle Jurassic and Early Cretaceous magmatic rocks are exposed in the Lengshuikeng District(Fig.2).The Jurassic igneous rocks are mainly granitic including the Yinluling, Yinzhushan,Biaojia,and Yinglin porphyries.The Yinzhushan granite porphyry has been dated as162–159Ma (Meng et al.2007;Zuo et al.2010).The Early Cretaceous rocks include quartz syenite porphyry,rhyolite porphyry, alkali-feldspar granite porphyry,and mafic dykes(Fig.2). The quartz syenite porphyries crop out in the southeastern and northwestern parts of the Lengshikeng District(Fig.2),with widely dispersed chloritization,sericitization,silicifica-tion,and carbonatization,with associated pyrite.Wang et al.(2010c )and Meng et al.(2007)reported that rhyolite porphyry and alkali-feldspar granite porphyry cut all the granite por-phyry and pyroclastic carbonate ore-hosted rocks (Fig.3)as well as the quartz syenite porphyry.The least hydrothermally altered granite porphyries contain phenocrysts (15–35%)of quartz,plagioclase,K-feldspar,and biotite in a groundmass (65–85%)of subhedral K-feldspar,quartz,plagioclase,and minor biotite.Accessory minerals (∼1%)are mainly magnetite,zircon,and apatite.Most quartz crystals are xenomorphic and exhibit undulose extinction.The quartz syenite porphyries contain phenocrysts (33–55%)of K-feldspar (∼20%),biotite (∼10%),and plagioclase (∼8%)in a groundmass (45–67%)of subhedral K-feldspar,biotite,and quartz.K-feldspar phenocrysts are euhedral to subhedral,have a grain size of 2–5mm,and are locally replaced by sericite.Plagioclase phenocrysts are euhedral to subhedral,3–6mm in size,with evidence of weak silicification and sericitization.Biotite phenocrysts are 0.5–1.0mm in size and show alteration to chlorite and carbonate.Ore bodies and wall rock alterationAmong the various ore deposits,the Baojia porphyry-hosted deposit is the most important,accounting for 52%of the total ore reserve in the Lengshuikeng District (Fig.2).The porphyry-hosted ore bodies (Fig.3a )are associated with NNE-striking F 2reverse faults or comprise of fracture fillings in veins and breccias.Associated with the porphyry-hosted ore bodies is a distinct zoning of alteration and ore minerals,both vertically and laterally (Fig.3b,c ).An inner (or proximal)zone in the granite porphyry is characterized by enrichments in lead,zinc (with grade Pb+Zn >5%)with minor disseminated chalcopyrite and pyrite,and with minor chlorite and sericite alteration.The intermediate zone surrounds the inner zone near the contact between the granite porphyry and country rocks.This intermediate zone exhibits strong sericitization,carbonatization,and silicification,and in some cases,high-grade native silver mineralization (Ag >200g/t),with minor galena –sphalerite vein mineralization (Fig.4a ).The outer peripheral (or distal)zone is hosted by volcano-sedimentary country rocks to the granite porphyry and is de-fined by weakly developed silver,galena,sphalerite veins (Ag <100g/t;Pb+Zn <2%),and vein sericite and carbonate.Stratabound mineralization is hosted by manganese –iron carbonate layers of the E ’huling Formation (∼5.0–33.1-m thickness)between tuffaceous sandstone and rhyolitic crystal tuff (Jiangxi Bureau of Geology and Mineral Exploration and Development (JBGMED)1982;Meng et al.2007).These rocks are characterized by high-grade native silver minerali-zation (Ag >200g/t),lead,zinc (with grade Pb+Zn >5%)as veins and breccias,with minor vein chlorite,sericite,and carbonate (Fig.4b,c ).Ore mineralogy and paragenesisThe mineralization in stratabound and porphyry-hosted ores can be divided into three stages (Fig.5):stage 1,pyrite –chalcopyrite –sphalerite;stage 2,silver minerals –galena –sphalerite;and stage 3,pyrite –quartz –calcite.The mineral assemblage of stage 1is dominantly pyrite and Fe-rich sphal-erite,with small amounts of chalcopyrite,cubanite,galena,arsenopyrite,pyrrhotite,and minor quartz (Fig.6a –c ).Stage 1mineralization was accompanied by chloritization and sericitization,replacing K-feldspar and plagioclase crystals in rhyolitic crystal tuff and granite porphyry.Siderite is intergrown with sphalerite but occurs mostly as overgrowths on sphalerite or as monomineralic cement in breccias and thin veinlets.Stage 2was the principal stage of silver –lead –zinc mineralization.This stage is characterized by sericitization and carbonatization,and minor chloritization.The silver –lead –zinc minerals of stage 2fill the manganese –ironFig.2Geological map of the Lengshuikeng Ag –Pb –Zn ore district (after JBGMED 1982).Sections a and b are shown in Fig.3a –ccarbonate stratabound fractures.The dominant silver minerals are acanthite (Ag 2S)and native silver,which occur in fissures within manganese –iron carbonate or in the intergranular space between manganese –iron carbonate and early sulfides.In ad-dition,fine-grained canfieldite (Ag 8SnS 6),proustite (Ag 3AsS 3),aerosite (Ag 3SbS 3),Ag-bearing tetrahedrite (Cu 12Sb 4S 13),and kustelite (Ag,Au)occur in the intergranular pores of manganese –iron carbonate or as inclusions in galena,sphalerite,and other sulfides.The galena is euhedral and coarse-grained (Fig.6e ).V eins,veinlets,or disseminated silver minerals –gale-na –sphalerite are disseminated in the intergranular pores of manganese –iron carbonate (Fig.6f –h ).Stage 1pyrite is cut by galena and sphalerite vein (Fig.6b ),sphalerite surrounded by galena (Fig.4d ),and sphalerite cut by ankerite –galena vein.InFig.3Geological features along sections a and b of the Baojiao deposit in the Lengshuikeng ore district (after JBGMED 1982):a relationship of ore bodies,b alteration zoning,and c mineralized zonestage 3,ore minerals are dominated by pyrite,with lesser galena,pyrrhotite,and arsenopyrite.Calcite,quartz,and quartz –pyrite are characterized by open-space filling textures such as comb,veins,and veinlets and cut the stage 2galena or sphalerite veins (Figs.4e,f and 6d ).Sampling and analytical procedure for stable and radiogenic isotopesSamples were collected from ore materials at the −80,−120,−152,and −160m levels of underground workings,outcropsFig.4Macroscopic features of samples selected for ore mineralogy and paragenesis studies.a Porphyry-hosted ore with vein galena and with chloritization and sericitization.b Brecciated stratabound-type ore.c Stratabound-type ore with vein sphalerite and galena and with chloritization,sericitization,and carbonation (Lu et al.2012).d Sphalerite phase (stage 1)surrounded by galena (stage 2)(Lu et al.2012).e Pyrite (stage 1)intersected by quartz vein (stage 3).g Disseminated ore intersected by pyrite vein (stage 3).Sp sphalerite,Gn galena,Py pyrite,Chl chloritization,Ser sericitization,Cbn carbonation,and Qz quartz(Fig.2)at ∼160m.s.l.elevations,and two drill holes in the Lengshuikeng ore district.Pure mineral concentrates from the porphyry-hosted and stratabound ores and wallrocks were prepared using a combination of heavy liquid and magnetic-and hand-picking techniques,and these were then checked by X-ray diffraction to ensure mineral purity.Sulfur isotope analyses of sphalerite,galena,and pyrite were carried out at the Resource and Environment Analysis Centre of the Geochemistry Institute,Chinese Academy of Sciences.Pyrite,galena,and sphalerite were combusted with CuO at 1,000°C,and the sulfur isotopic compositions was determined on a MAT-253mass spectrometer.The sulfur isotopic compositions were reported relative to the Canyon Diablo Triolite (VCDT)standard.Routine analytical precision for standards material was ±0.2‰.Rhodochrosite,siderite,calcite,and ankerite were handpicked under a stereomicroscope and washed with dis-tilled water.Carbon and oxygen isotopic measurements were made in the Environmental Isotope Geochemistry Laboratory of the Institute of Geology and Geophysics,Chinese Academy of Science.About 150μg was reacted with phosphoric acid at 72°C for 6h using a GasBench II (Thermo-Finnigan).TheCO 2produced was analyzed for carbon and oxygen isotope ratios using a MAT-253isotope ratio mass spectrometer.The carbon and oxygen isotope measurements have a precision better than 0.1‰.Accuracy and precision were routinely checked by running the carbonate standard NBS-19after every six measurements of the samples.Carbon isotope ratios are reported relative to Peedee belemnite (V-PDB),and oxy-gen isotope ratios are reported relative to standard mean ocean water (V-SMOW).Rb –Sr analyses were performed at the Laboratory for Radiogenic Isotope Geochemistry (LRIG),Institute of Geology and Geophysics,Chinese Academy of Sciences (Li et al.2006).Sphalerite grains in Teflon®vessels,washed ultrasonically in analysis-grade alcohol and millipore water,were dissolved using 0.3ml 3N HNO 3and 0.1ml HF at 120°C.Rb and Sr were separated using ion exchange col-umns.Rb and Sr concentrations were measured by isotope dilution,and a mixed 87Rb/84Sr spike solution was used.Isotopic ratios of Rb and Sr were measured on an IsoProbe-T mass spectrometer at the LRIG.Correction of mass frac-tionation for Sr isotopic ratios was based on an 88Sr/86Sr value of 8.37521.Repeated measurements of NBS987Sr standard solution gave an average value of 87Sr/86Sr ratio of 0.710250±31(2σ).One quartz syenite porphyry sample in the Lengshuikeng District (Fig.2)was selected for U –Pb zircon dating by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA –(MC)–ICP –MS)at the Tianjin Institute of Geology and Mineral Resources,Tianjin,China (Li et al.2009).The zircon was ablated with a NUP193-FX ArF Excimer laser using a spot diameter of 35μm,with constant 13–14J/cm 2energy density and a frequency of 8–10Hz.The ablated material was carried in He into the plasma source of a GVI.All measurements were made in static mode,using Faraday cups for 238U,232Th,208Pb,206Pb,207Pb,and an ion-counting channel for 204Pb.A common Pb correction is achieved by using the measured 204Pb and assuming an initial Pb composition from Stacey and Kramers (1975).Analytical results Sulfur isotope dataThe δ34S values determined from 20sulfide samples collected in this study and δ34S data from previous works in the same area (Meng et al.2007;Xu et al.2001;No 912Geological Surveying Team (NGST)1997)are listed in Table 1and plotted in Fig.7.The δ34S values of sulfides in ores range from −3.8to 6.9‰with an average of 2.0‰.However,the majority of sulfide minerals have δ34S values between −1andFig.5Mineral paragenesis of the porphyry-hosted and stratabound ores in the Lengshuikeng ore district showing mineral assemblages4‰.The ranges of δ34S values of sulfides in the porphyry-hosted and stratabound ores from −3.8to 6.9‰(average 2.3‰)and −2.4to 4.9‰(average 1.7‰),respectively.The δ34S values of pyrite in the porphyry-hosted ores in pyrite –chalcopyrite –sphalerite (stage 1)range from 2.2to 4.9‰(average 3.9‰).However,the δ34S values of pyrite,sphaler-ite,and galena in the porphyry-hosted ores in silver minerals –galena –sphalerite (stage 2)range from −0.4to 3.1‰(average 2.0‰),0.9to 4.3‰(average 2.8‰),and −2.4to 2.8‰(average −0.4‰),respectively.The δ34S values of pyrite,sphalerite,and galena in the stratabound ores in pyrite –chal-copyrite –sphalerite (stage 1)range from 2.3to 4.0‰(average 3.3‰),3.5to 6.9‰(average 5.0‰),and 3.2‰,respectively.However,the δ34S values of pyrite,sphalerite,and galenainFig.6Photomicrographsshowing the salient mineralogical and textural aspects.a Pyrite disseminated in porphyry-hosted ore and replacing K-feldspar crystals.b Granite porphyry fragments cemented by sulfide minerals with brecciated vein structure and pyrite breccias intersected by galena and sphalerite vein (Su 2013).c Chalcopyrite,galena,andsphalerite in rhyolitic crystal tuff,with chloritization andsericitization.d Galena with “crumpled ”texture and galena and sphalerite intersected by quartz vein.e Dolomite replaced by sphalerite and sphalerite surrounded by galena.fAggregate of acanthite in the intergranular pores of ferromanganese carbonate (Lu et al.2012).g Subhedral native silver occurring in the intergranular pores of ferromanganese carbonate(Lu et al.2012).h Native silver vein in ferromanganese carbonate (Lu et al.2012).Aca acanthite,Cpy chalcopyrite,Dol dolomite,Fer ferromanganese carbonate,Gn galena,Ksp K-feldspar,Py pyrite,Qz quartz,Slv native silver,and Sp sphaleritethe stratabound ores in silver minerals–galena–sphalerite (stage2)range from2.3to2.8‰(average2.5‰),0.9to 3.8‰(average2.2‰),and−3.8to2.4‰(average0.1‰), respectively.Carbon and oxygen isotope dataThe carbon and oxygen isotope values of carbonate minerals were determined for nine hydrothermal siderite samples col-lected from the stratabound ores and crystal tuffs with weak alteration,two calcite vein samples,five ankerite vein sam-ples,and eight manganese–iron carbonate samples(rhodo-chrosite and siderite)from the volcano-sedimentary strata. Carbon and oxygen isotopic compositions are listed in Table2and plotted in Fig.8.Theδ13C PDB values in rhodochrosite and siderite samples from the volcano-sedimentary strata vary from−7.0to−2.4‰(Table2).Theδ13C PDB values of hydrothermal carbonates in siderite,calcite,and ankerite samples vary from−7.2to −2.2‰,from−3.3to−1.5‰,and from−3.9to−2.0‰,Table1Sulfur isotopic compositions of sulfide minerals from the Lengshuikeng Ag–Pb–Zn ore districtSample no.Mineral Stageδ34S(‰)Sample no.Mineral Stageδ34S(‰)Sample no.Mineral Stageδ34S(‰)Stratabound ores Stratabound ores Porphyry-hosted oresZK504Py1 3.7PD152-4Gn2 1.1ZK10412-1b Py2 1.9Zk13Py1 4.0ZK136-1Gn2−1.4L14c Py2 2.0ZK410-2Py1 3.0LSK-74a Gn2 1.8L15c Py2 1.7No12Py1 2.3N4-8-102b Gn20.1L16c Py2 2.4ZK515Py1 3.2S4-0-28b Gn20.2L26c Py2 1.5 LSK-9a Py1 3.5LSK-101a Gn2 2.0126-2-1a Py2−0.4 LSK-9-1a Py1 3.6LSK-102a Gn2 2.4130N-4a Sp2 4.3 LSK-41a Py1 2.7So-8-11b Gn2−1.7130S-1a Sp2 2.9 LSK-42a Py1 3.6N4-8-77b Gn2−0.1L17c Sp2 3.2ZK136-1Sp1 4.3N4-8-13b Gn2 1.1L18c Sp2 2.9PD160-6Sp1 5.8N4-8-96b Gn2−0.9L19c Sp2 2.6PD80-10Sp1 5.1N8-4-20b Gn20.2L20c Sp2 1.9Zk197Sp1 3.5So-12-23b Gn2−3.8LSK-77a Sp2 4.6No7Sp1 5.2N4-8-102b Py2 2.7LSK-78a Sp2 3.6PD152-4Sp1 4.6N8-8-26b Py2 2.3L27c Sp2 1.5ZK515Sp1 6.9So-8-11b Py2 2.3L28c Sp20.9 LSK-101a Sp1 4.6Porphyry-hosted ores130N-4a Gn2 1.2PD80-13Sp1 5.0L1c Py1 4.9130S-1a Gn20.1 LSK-74a Sp1 4.8L2c Py1 4.9LSK-77a Gn2 1.6ZK515Gn1 3.2L3c Py1 4.1L21c Gn2 2.8N4-8-77b Py1 3.0L4c Py1 4.1L22c Gn2−0.3N8-0-150b Py1 4.0L5c Py1 3.6L23c Gn2−0.9ZK136-1Py2 2.8L6c Py1 3.6L24c Gn2−1.7So-8-11b Sp2 2.3L7c Py1 2.2L25c Gn2−2.3N4-8-77b Sp2 2.8L8c Py2 3.1L29c Gn2−0.1N4-8-102b Sp2 1.0L9c Py2 3.0L30c Gn2−0.2 LSK-102a Sp2 3.8L10c Py2 2.6L31c Gn2−0.4So-12-23b Sp20.9L11c Py2 2.5L32c Gn2−0.9N4-8-77b Gn2−0.8L12c Py2 2.3L33c Gn2−1.1Zk29Gn2 1.6L13c Py2 2.3L34c Gn2−1.2Zk311Gn2−0.1ZK10010-718b Py2 2.3L35c Gn2−2.4Zk198-1Gn20.2ZK10010-719b Py2 1.4Sp sphalerite,Gn galena,Py pyritea Meng et al.(2007)b Xu et al.(2001)c NGST(1997)isotopic composition of sulfideminerals in the Lengshuikeng oredistrict.a All sulfide minerals.bSulfide minerals in porphyry-hosted ore.c Sulfide minerals instratabound oreTable2Carbon and oxygen isotopic compositions of carbonate minerals from the Lengshuikeng Ag–Pb–Zn ore district.Theδ18O SMOW values were calculated fromδ18O PDB values using the formula:δ18O SMOW=1.03091×δ18O+30.91(González and Lohmann1985)Sampling location Sample no.Lithology Mineralδ13C PDBδ18O SMOW ∼152m elev.PD152-3Manganese–iron carbonate Rhodochrosite−3.311.6∼160m elev.160-4Manganese–iron carbonate Rhodochrosite−2.418.0∼120m elev.PD120-9Manganese–iron carbonate Siderite−3.914.6∼152m elev.PD152-11Manganese–iron carbonate Siderite−5.313.0 13703drill hole Zk315Manganese–iron carbonate Siderite−2.716.8 15150drill hole Zk18Manganese–iron carbonate Siderite−5.914.9∼152m elev.PD152-10Manganese–iron carbonate Siderite−5.513.4 13704drill hole Zk198-1Manganese–iron carbonate Siderite−7.019.5∼160m elev.160-3Crystal tuff Hydrothermal siderite−2.217.9 13213drill hole ZK513-1Crystal tuff Hydrothermal siderite−3.917.5 15150drill hole Zk32Crystal tuff Hydrothermal siderite−4.213.5∼120m elev.PD120-5Crystal tuff Hydrothermal siderite−5.917.5∼160m elev.160-6Stratabound ore Hydrothermal siderite−3.816.8∼120m elev.No5Stratabound ore Hydrothermal siderite−5.413.6∼120m elev.PD120-6Stratabound ore Hydrothermal siderite−5.913.5∼152m elev.PD152-4Stratabound ore Hydrothermal siderite−3.613.7 13213drill hole ZK509Stratabound ore Hydrothermal siderite−7.212.8 15150drill hole Zk33Ankerite vein Ankerite−3.313.1 15150drill hole Zk34Ankerite vein Ankerite−2.013.5 15151drill hole ZK136Ankerite vein Ankerite−3.313.9 15151drill hole Zk138-2Ankerite vein Ankerite−3.911.0 13703drill hole Zk309Ankerite vein Ankerite−3.012.4 15151drill hole ZK138-3Calcite vein Calcite−1.510.9 13703drill hole Zk313Calcite vein Calcite−3.311.9 Surface a83Carboniferous Limestone0.619.6a NGST(1997)respectively (Table 2).The δ18O SMOW values in rhodochrosite and siderite samples from the volcano-sedimentary strata vary from 11.6to 19.5‰and from 10.9to 11.9‰,respectively (Table 2).The δ18O SMOW values of hydrothermal carbonates in siderite,calcite,and ankerite samples vary from 12.9to 17.9‰,from 10.9to 11.9‰,and from 11.0to 13.9‰.One Carboniferous limestone sample is isotopically heavy (19.6‰;NGST 1997).Rubidium and strontium isotope dataThe Rb –Sr analytical data of sphalerite are given in Table 3.The sphalerite was separated from the manganese –iron car-bonate ores in the silver minerals –galena –sphalerite stage.Data regression for isochron ages and weighted mean values were performed using the ISOPLOT software (Ludwig 2001),with 2%error for 87Rb/86Sr ratios and 0.05%error for 87Sr/86Sr at the 95%confidence level.The analytical data for sphalerite yielded an age of 126.9±7.1Ma (Fig.9)with an initial 87Rb/86Sr ratio of 0.71490(mean square weighted deviation (MSWD)=0.94).Zircon U –Pb geochronologyMeasured 206Pb/238U ages from individual zircons are shown in Fig.10,and the analytical results of LA –ICP –MS U –Pb dating are listed in Table 4.For the quartz syenite porphyry (sample T10),analyses from 20spots cluster close to the concordia,yielding a weighted mean 206Pb/238U age of 136.31±0.81Ma (2σ,MSWD=1.3;Fig.10).DiscussionAges of magmatism and mineralizationThe results presented in this study together with those from previous investigations suggest multistage magmatism in the Lengshuikeng and adjacent regions.The magmatic activity took place principally during three periods,in the Jurassic,earlier Early Cretaceous,and later Early Cretaceous.The Jurassic magmatism in the Lengshuikeng District is represented by the emplacement age of the graniteporphyry,Fig.8Plots of calculated δ18O SMOW versus δ13C PDB from various samples in the Lengshuikeng ore district.Carbonate fields are from previous studies.The data are from four different materials including marine carbonate (Baker and Fallick 1989;Hoefs 1997),continental carbonate (Hoefs 1997),sedimentary organic matter carbon (Hodson 1977;Hoefs 1997),and magma-mantle carbonate (Taylor et al.1967;Valley 1986;Ray et al.1999).This plot offers information about various processes of CO 2and carbonate ions including meteoric water influence,sea water penetration,sediment contamination,and high temperature influence,low temperature alteration (Deines 1989;Demrny and Harangi 1996;Demeny et al.1998;Hoernle et al.2002),decarboxylation and oxidation (Hofmann and Bernasconi 1998),decarbonate and carbon-ate dissolution (Lorrain et al.2003),crystallization differentiation with no significantly influence on the oxygen,and carbon isotopic composition (Santos and Clayton 1995;Bindeman 2008)Table 3Rb –Sr isotopiccompositions of sphalerite in the Lengshuikeng Ag –Pb –Zn ore districtSample no.Mineral Rb (μg/g)Sr (μg/g)87Rb/86Sr87Sr/86Sr(±2σ)I sr PD152-7Sphalerite 1.390 4.0800.98910.716557±340.71435ZK205Sphalerite 0.0960.9720.28660.715641±380.71500ZK513-1Sphalerite 2.060 1.820 3.27260.720846±220.71354No4Sphalerite0.9603.9600.70190.716056±180.71449。