ISOTOPE GEOCHEMISTRY OF DACHA GOLD DEPOSITS IN TIBET
ISOTOPE GEOCHEMISTRY OF DACHA GOLD DEPOSITS IN TIBET
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发表时间：
2002
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通讯作者：
Xiao Run
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作者：
Xiao Run
通过对西藏大岔金矿床流体包裹体中S、Pb、Si同位素和水的H、O同位素的研究，发现其δ 34 S CDT值范围为11 ‰ ~ 16 ‰，平均值为14 ‰，接近大气硫和深源岩浆硫，地层、岩浆岩和矿石在构造格局上均位于造山带周围;石英脉的均一温度为440 8 ~ 501 8℃，δ DV-SMOW为-126‰ ~-98‰，δ OV-SMOW为2 0 8 ‰ ~ 8 84‰，流体包裹体中水为典型的岩浆水; NBS-28的δ 30 Si值为-0.5 ‰ ~-0.6 ‰，硅可能来自基性和中基性岩浆岩。西藏大岔地区原生金矿床的成矿物质来源主要有三个方面。第一个物源为木嘎岗日群第二、三组海相热水沉积物，其中含有大量成矿物质。第二类是深埋于特提斯地层中的基性、中基性岩浆岩，为金矿床提供了大部分的金、硅。中酸性岩浆岩是提供各种成矿物质的主要岩石。本区成矿流体主要为经大气降水或海水强烈改造的岩浆热液。
Based on the studies of S, Pb, Si isotopes and H,O isotopes of water in the fluid inclusions from Dacha gold deposits in Tibet, the range of δ 34 S CDT value is 1 1‰-1 6‰ with average 1 4‰,which close to meteoric sulphur and depth origin magma sulphur; the leads of stratum, magma rock and ore are located around orogen belt in the pattern of tectonic; the temperatures of homogenization of quartz veins range from 440 8 to 501 8℃, δ D V-SMOW from -126‰ to -98‰ , δ O V-SMOW from 2 08‰ to 8 84‰, that means the water in fluid inclusion is typical magmatic water; the δ 30 Si NBS-28 ranges from -0 5‰ to -0 6‰,and the silicon possibly come from the basic and intermediate basic magma rocks. Three sources are recognized for the metallogenic material of the primary gold deposits in Dacha area,Tibet. The first source is the second and third formations of the Mugagangri group, the marine thermal water sediments which bear a lot of metallogenic material. The second source is deep buried basic and intermediate basic magmatic rocks which occur in Tethys bed and provide most of the gold and silicon for the gold deposits. The third one is intermediate acid magmatic rocks which are the main rocks providing various matellogenic material. The main matellogenic fluid of this area is the magmatic hydrothermal fluid reformed strongly by meteoritic water or sea water.