云南墨江金矿床硅质岩沉积环境的地球化学探讨  

Geochemistry of depositional environment of siliceous rocks from Mojiang gold deposit in Yunnan Province

作　　者：谢桂青[1] 胡瑞忠[1] 方维萱[1] 漆亮[1] 

机构地区：[1]中国科学院地球化学研究所矿床开放实验室,贵州贵阳550002

出　　处：《地球化学》2001年第5期491-497,共7页Geochimica

基　　金：国家杰出青年科学基金(49925309);国家重点研究发展规划项目(G1999043200);云南省院校科技合作项目(YK98008-3)

摘　　要：墨江金矿床金厂组中下段硅质岩的形成与热水沉积作用有关,但中段受到正常化学沉积作用的影响。根据硅质岩的地球化学特征,初步讨论了硅质岩的沉积(构造)环境。硅质岩的δCe、稀土元素对Ce/La-La/Yb图解、δ30Si和Sr/Ba值的特征表明它形成于海水较深的沉积环境。根据硅质岩MnO/TiO2、Al/(Al+Fe)、(La/Ce)N、δCe和(La/Yb)N的特征推测它形成于大陆边缘-远洋盆地过渡位置。结合岩石组合、地球化学特征和同位素年代学,认为墨江金矿床硅质岩的沉积环境可能为晚泥盆世后期扬子地块被动大陆边缘快速裂陷的深海槽盆,它不是哀牢山蛇绿岩套“三位一体”中的一部分。The siliceous rocks of Jinchang Formation are a product of hydrothermal sedimentation in Mojiang gold deposit, but the medium member attached to Jinchang Formation mixed normal chemical sediments. Depositional environment of siliceous rocks is discussed according to element geochemistry and silicon isotopic characteristics. The value of δCe, the diagram of Ce/La versus La/Yb, δ30Si and Sr/Ba of the siliceous rocks show that the rocks were formed in deep sea environment. According to value of MnO/TiO2, Al/(Al+Fe), (La/Ce)N, δCe and (La/Yb)N of the siliceous rocks, it is indicated that they probably deposited in transitional area between the continental margin and oceanic basin environment. According to rock assemblage and geochemistry and isotopic chronology characteristics, the siliceous rocks are probably located to rapid split deep sea slot of passive continental margin of Yangtze Block of Late Devonian, and are not considered to be a part of Ailaoshan ophiolites.

关 键 词：沉积环境 地球化学 硅质岩 墨江金矿床 云南 热水沉积作用 

分 类 号：R618.51[医药卫生—外科学] P59[医药卫生—临床医学]