岩浆流体对冲绳海槽海底成矿热水系统的可能贡献  

Possible Contribution of Magmatic Fluids to Seafloor Ore-forming Hydrothermal System in the Okinawa Trough

作　　者：侯增谦[1] 艾永德[1] 曲晓明 张琦玲 唐绍华 

机构地区：[1]中国地质科学院,北京100037

出　　处：《地质学报》1999年第1期57-65,共9页Acta Geologica Sinica

基　　金：国家攀登项目(编号:95-预-39);国家自然科学基金(编号:49773177)

摘　　要：海底火山活动区成矿热液流体来源长期存在争议。尽管海水来源说更为流行,但本文提供的下列证据表明,来自长英质岩浆的流体对冲绳海槽现代活动热水成矿系统有较大贡献:①冲绳海槽JADE热水区出现异常高热流,其下方1～2km处存在浅位长英质岩浆房;②CO_2、烃类、H_2等气体在热水成矿体系中极度富集甚至形成独立气流,与热水流体共存。气体的碳、氦同位素资料表明其来自长英质岩浆体系;③JADE成矿热水系统存在异常高温(330～392℃)和高盐度(6.7％～7.5％)热流体端元;④热水蚀变岩具较高的δ^(18)O组成(12.3‰～14.7‰),据热液石英δ^(18)O和流体充填温度估算的初始流体δ^(18)O组成与岩浆水相当。The sources of ore-forming hydrothermal fluid in the seafloor volcanic activity regions has been debated matter. Although the hypothesis of the source from sea water is more prevalent, the following evidences show that the fluid derived from felsic magma makes more contributions to the modern active hydrothermal ore-forming system in the Okinawa trough than sea water :① anormally high heat flow values appear in JADE hydrothermal area of the Okinawa trough ,and a shallow-level felsic magma chamber occurs at depths of 1 - 2km beneath seafloor; ②gases such as CO2, hydrocarbon and H2 are extremely concentrated and even form independent gas flow coexisting with hydrothermal fluids in ore-forming hydrothermal system. C and O isotopic data demonstrate that these gases are derived from the felsic magma system; ③the JADE ore-forming hydrothermal system contains hydrothermal fluid end-member with anormally-high temperature (330-382℃) and high salinity (6. 7%-7. 5%); ④hydrothermally altered rocks have higher δ18O values (12- 3‰-14. 7‰). Based on the hydrothermal quartz δ18O and the filled temperature of fluid, theδ18O of initial fluid is estimated to be equivalent to that of magmatic fluid.

关 键 词：岩浆流体 冲绳海槽 海底成矿 热水系统 

分 类 号：P744[天文地球—海洋科学] P588.11