湖南宝山铜多金属矿床流体包裹体特征及氢氧同位素地球化学的初步研究_轩一撒

湖南宝山铜多金属矿床流体包裹体特征及氢氧同位素地球化学的初步研究*

轩一撒1，2袁顺达2＊＊弥佳茹2赵盼捞2原垭斌2张东亮3

XUAN YiSa1，2，YUAN ShunDa2＊＊，MI JiaRu2，ZHAO PanLao2，YUAN YaBin2and ZHANG DongLiang3

1.中科遥感科技集团有限公司，天津300000

2.中国地质科学院矿产资源研究所，北京100037

3.中南大学地球科学与信息物理学院，长沙410083

1.China Remote Sensing Technology Group Co.，Ltd，Tianjin300000，China

2.Institute of Mineral Resources，Chinese Academy of Geological Sciences，Beijing100037，China

3.Earth Science＆Geophysics Information College，Central South University，Changsha410083，China

2016-08-27收稿，2016-12-11改回.

Xuan YS，Yuan SD，Mi JR，Zhao PL，Yuan YB and Zhang DL.2017.Preliminary studies on the fluid inclusions and H-O isotopic geochemistry of the Baoshan copper polymetallic deposit，Hunan Province.Acta Petrologica Sinica，33（3）：873－886

Abstract The Baoshan deposit is the largest Cu deposit in southern Hunan Province，which is located on the connection part of Qin-Hang NE-trending ore belt and Nanling EW-trending polymetallic metallogenic belt.The Cu-polymetallic mineralization is associated with granodiorite porphyry.Copper-molybdenum ore bodies occur as disseminated ore in skarn between granodiorite porphyry and carbonate rocks，while lead-zinc sulfide ores occur as veins in the fault damage zone and within intrastratal fracture belts of the Carboniferous strata.Based on detailed field investigation of the Baoshan copper polymetallic deposit，we have carried out systematic microscope observation，detailed micro-thermometric measurement of the fluid inclusions，Laser Raman spectroscopic and H-O isotopic analyses，and preliminarily discussed the fluid evolution of the deposit.The following conclusions are obtained：（1）The mineralization of the Baoshan deposit can be divided into four stages，i.e.，the skarn stage，retrograde stage，metal sulfides stage and fluorite-calcite stage；（2）The main types of fluid inclusions for Baoshan deposit are liquid-rich inclusions.The ore-forming fluid of Baoshan deposit

belongs to H

2O-NaCl system.There is a little CO

2

in the gas phase and a few NaCl daughter minerals in the fluid inclusions；（3）The

homogenization temperatures of the fluid inclusions range from430ħto＞550ħ（mainly above550ħ）and the salinities are between 13.4%and21.98%NaCleqv in the skarn stage.The homogenization temperatures of the fluid inclusions range from211.8ħto395ħ（mainly260 320ħand360 395ħ）and the salinities range from3.71%to19.53%NaCleqv in the retrograde stage.The dramatic decrease in pressure from skarn stage to retrograde stage can be probably attributed in the transition from lithostatic pressure to hydrostatic pressure.In metal sulfides stage，the homogenization temperatures range from156.7ħto323.1ħ（mainly190 240ħ）and the salinities range from3.71%to19.84%NaCleqv.In fluorite-calcite stage，the homogenization temperatures are between100ħand266.5ħ（concentrated in145 180ħ）and the salinities are3.71% 19.84%NaCleqv.The trapping pressure can be estimated to be about23.8 169.9MPa which changed from lithostatic pressure to hydrostatic pressure，equivalent to a depth of2.25 6.29km which is centered in4 6km；（4）Theδ18O

H2O

values of the retrograde stage ore fluids which range from3.37ɢto7.47ɢ，are

correspondingδD

H2O values between－64ɢand－70ɢ.Theδ18O

H2O

values of metal sulfides stage and fluorite-calcite stage fluid are

from0.33ɢto5.28ɢ，implying a significant input of meteoric water.In general，the ore-forming fluid system varies from early，deep，magmatic fluid to late，shallow，meteoric water.Thus the ore-forming fluid was mainly magmatic water in the early stage，with 1000-0569/2017/033(03)-0873-86Acta Petrologica Sinica岩石学报

＊＊＊本文受国家自然科学基金项目（41373047、41173052、41672095）、中央级公益性科研院所基本业务费专项资金（K1204）和地质调查项目（N1307）联合资助．

第一作者简介：轩一撒，男，1990年生，硕士，地质工程师，从事高光谱遥感地质研究，E-mail：xuanys@chinarsgeo．com

通讯作者：袁顺达，男，1980年生，博士，研究员，矿床地球化学专业，E-mail：shundayuan@cags．ac．cn