西藏羊八井现代地下热水系统硫矿的成矿作用

SULFUR MINERALIZATION OF MODERN GEOTHERAMAL SYSTEM IN YANGBAJING BASIN OF XIZANG

通过对羊八井盆地地热流体的地球化学、气体成分、同位素特征以及泉华、岩矿等资料的研究 ,确认该地下热水溶液中的水主要来自大气降水 ,部分来自深部 ;矿质大部分源自对围岩的淋滤和溶解 ,少部分物质 ,如易挥发成分则与岩浆体有关 ;热源则由地壳浅部岩浆体供给。根据羊八井地热水成矿作用特点和矿化分布规律 ,提出成矿区主要位于地热流体卸压排泄系统成矿的论点 ,并建立了羊八井盆地地热水系统成矿概念模型。

The geothermal heat fluids circulating about within the Yangbajing basin of Xizang were probed with respect to their geochemistry , gas composition and isotopic characters, coupled with the studies of the related sinterite, rocks and minerals. The results indicated that the water of the head fluids was sourced dominantly from meteoric water and locally from underground depths, that the mineralizing materials were related mainly to the leaching of the trapping rocks and that few mounts, such as volatile components, were caused by heat diffusion of shallow seated magmatic activities. Sulfur mineralization took place mostly at places where the geothermal heat fluids could release pressure to move, an argument that is based on knowledge of the mineralizing features and distribution and on establishment of a metallogenetic model for the geothermal system. Sulfur and sulfides owed their origins, to a great extent, to microbial contributions in the geothermal basin.