山东玲珑金矿床成矿流体地球化学特征

山东玲珑金矿床成矿流体地球化学特征

王可勇1,张春燕2,樊岳铭2,张晓东

3

1.吉林大学地球科学学院,长春 130061

2.山东招远玲珑金矿,山东招远 265400

3.辽宁五龙四道沟金矿,辽宁丹东 118000

摘要:玲珑金矿床第一成矿阶段与含金黄铁矿共生的石英中主要发育4种类型的原生流体包裹体:Ñ气液两相,Ò含CO 2三相,ÓCO 2,Ô单液相包裹体。流体包裹体成分激光拉曼光谱分析及测温结果显示:¹Ña 型包体,气液比10%~15%,均一温度为162.7~235.6e ,w (N aCl)(盐度)为4.65%~7.59%,气相平均摩尔分数为:H 2O 96.48%,CO 22.4%;ºÑb 型包体,气液比30%~45%,均一温度266.9~349.2e ,w (N aCl)为10.8%~13.4%,气相平均摩尔分数为H 2O 69.75%,CO 224.74%;»Ò型含CO 2包体,CO 2相所占比例为20%~90%,其均一温度为193.5~321.6e ,w (N aCl)2.9%~5.3%,CO 2相中,H 2O 的摩尔分数为27.72%,CO 2为70.6%。包裹体成分分析及测温结果综合研究认为,玲珑金矿成矿过程中存在大气降水热液与地幔来源流体的混合作用,前者与从流体中分离出的富CO 2流体混合,以不同比例被捕获形成Ò型包体;而与分异出CO 2后的CO 2不饱和地幔流体混合,被捕获形成Ñb 型包体。两种流体混合导致的含矿热液物化条件变化对金的沉淀成矿具有重要意义。

关键词:山东玲珑金矿床;流体混合作用;流体包裹体测温;激光拉曼光谱分析中图分类号:P618.51 文献标识码:A 文章编号:1671-5888(2008)02-0194-08

收稿日期:2007-06-25

基金项目:国家自然科学基金项目(40572117);吉林大学博士科研启动基金

作者简介:王可勇(1965)),男,河北乐亭人,教授,博士,主要从事矿床学及流体包裹体的研究,E -mail:w angky @jlu.

。

Geochemical Characteristics of Ore -Forming Fluids

of the Linglong Gold Deposit in Shandong Province

WANG Ke -yong 1,ZH ANG Chun -y an 2,FAN Yue -m ing 2,ZH ANG Xiao -do ng 3

1.Colleg e of Earth S cie nces ,J ilin Univ er sity ,Ch angch un 130061,China

2.L ing long Gold M ine ,Zhaoyuan,S handong 265400,China

3.Sid aog ou Gold M ine ,Dandong ,L iaoning 118000,China

Abstract:Four types of primary fluid inclusions dev elo ped in quartz that inter grow th with gold -bearing pyrite in the Ling long g old deposit,namely,Ñaqueo us tw o -phase;Òcarbon diox ide -bearing three -phase;Ócarbon diox ide and Ôo nly liquid aqueous phase,respectively.The laser Rom an spec -tro scopic analy sis for com position and the microtherm ometric study o f fluid inclusio ns indicate that:¹

ty pe Ña fluid inclusions,in w hich the vapor vo lum es occupy 10%-15%,their homo genization tem pe -rature is 162.7-235.6e ,salinity is 4.65%-7.59%NaCl,the average co mpo sition of vapor phase is 96.48m ol%H 2O and 2.4mo l%CO 2;ºty pe Ñb fluid inclusio ns,in w hich the v apor volumes occupy 30%-45%,their homog enization temperature is 266.9-349.2e ,salinity is 10.8%-13.4%NaCl,the av er ag e co mpo sition of vapor phase is 69.75m ol%H 2O and 24.74m ol%CO 2;»ty pe Òfluid inclu -sions,w ith a w ide rang e o f 20%-90%for the carbo n dio xide vo lum es in fluid inclusio ns,their homo gen-i

第38卷 第2期

2008年3月

吉林大学学报(地球科学版)

Jour nal of Jilin U niver sity(Ea rth Science Editio n)

Vo l.38 No.2

M ar.2008

zation temper ature is 193.5-321.6e ,salinity is 2.9%-5.3%NaCl,the av er ag e composition o f the car -bon diox ide phase is 27.72m ol%H 2O and 70.60mo l%CO prehensive study o f compositional and micro thermo metr ic analysis of fluid inclusio ns leads to the conclusion that fluid m ixing betw een meteoric w ater -deriv ed and m antle -derived hydrotherm al solutions ex isted in the m etallog enetic pro cess o f Linglo ng g old deposit.The form er are mix ed w ith CO 2-rich fluids separated from mantle -der iv ed so lu -tions and then captur ed at differ ent ratios formed type Òfluid inclusions;w hereas mix ed w ith CO 2-unsaturated fluids w hich w as the rem nants o f mantle -der iv ed solutions after CO 2separatio n,could be captured to form type Ñb fluid inclusio ns.T he changes in phy sico -chemical co nditions o f o re -forming solutions resulted from tw o kinds of fluid mix ing have g reat significances to g old mineralization.

Key words:Linglong gold deposit o f Shandong Province;fluid mix ing;microtherm ometry of fluid inclusion;Laser Ro man spectroscopic analysis o f co mpo sitio n

山东玲珑金矿床为我国规模最大的金矿床之一,它地处胶东招)掖金矿带东部,大地构造位置则位于胶东前寒武纪地盾之EW

向栖霞复式背斜北图1

玲珑金矿床地质图[3]

Fig.1

Geological map of Linglong gold deposit

1.第四系;

2.滦家河中-粗粒花岗岩;

3.玲珑片麻状黑云母花岗岩;

4.主压扭性断裂带及其产状、扭错方式;

5.矿脉及其产状;

6.中基性脉岩;

7.含黄铁矿石英脉矿体产状;

8.含黄铁矿绢英岩矿体和绢英岩化碎裂石英脉及碎裂花岗岩矿体编号

缘,沂沭断裂带东侧[1]。该矿床产于花岗岩体之中,矿区范围内大面积出露玲珑片麻状黑云母花岗岩,而作为本区基底的太古界胶东群变质岩则多以残留体形式零散分布于花岗岩体内。区域上,玲珑黑云母花岗岩与胶东群地层呈渐变接触关系,两者的稀

土元素及同位素地球化学特征十分相似,表明玲珑花岗岩系胶东群地层重熔作用的结果[1]

。已有的K -Ar 、Rb -Sr 等时线年龄表明其形成于(150.12?3.65)~(156.40?11.99)M a,为燕山期产物[2-3]。矿区范围内已发现40余条有工业价值的金矿脉(图1),其产出受区域性破头青韧性剪切带下盘次级韧-脆性剪切断裂带控制。这些矿脉平面上近平行或雁行状排列,剖面上呈共轭形产出,区内金矿化类型分

195

第2期 王可勇,等:山东玲珑金矿床成矿流体地球化学特征