重庆城口地区早前寒武系黑色岩系研究:(3)巴山组硅质岩中PGE异常的地球化学研究  

PRE-EARLY CAMBRIAN BLACK ROCK SERIES IN CHENGKOU DISTRICT,CHONGQING:(3) PGE GEOCHEMISTRY OF LOWER-CAMBIRAN CHERTS IN BASHAN GROUP.

作　　者：李晓彪[1] 罗远良 罗泰义[1] 周明忠[1] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室 [2]重庆市地质矿产勘查开发总公司205地质队,重庆永川402360

出　　处：《矿物学报》2007年第3期315-324,共10页Acta Mineralogica Sinica

基　　金：国家自然科学基金(40672053);重庆市地质矿产勘查开发总公司与中国科学院地球化学研究所合作项目

摘　　要：以猪草河剖面和羊儿坝剖面为例,进行硅质岩的PGE与微量元素等地球化学分析,结果表明:槽区硅质岩中的PGE异常受控于硅质岩中火山物质(蚀变成粘土矿物)的多少,PGE与Sc、Rb、Cs、Ti、Cr、Zr等具有良好的相关性;猪草河剖面远离陆源区,沉积厚度大,更靠近火山活动区域,接受火山粗碎屑物质的量多;羊儿坝剖面远离火山活动中心,主要接受了火山灰等细碎屑物质,更接近陆源区,受一定量的陆源碎屑物质影响。根据Cr/Co、Nb/Ta、Pd/Ir-Ni/Cu及Ni/Pd-Cu/Ir对岩浆性质的约束,当时岩浆性质为基性玄武岩。根据La-Y-Nb图解和Th-Hf-Ta图解的进一步约束,表明当时的火山岩浆性质为钙碱性的火山弧玄武岩。According to the geochemical analysis of the PGE and trace dements in the siliceous rocks from the Zhucaohe and Yang＇ erba sections, it is concluded that ： （1） the PGE anomaly relies on the quantity of magmagene ingredients （clay minerals, etc. ） in geosynclinal siliceous rocks, and the PGE are closely related with some elements such as Sc, Rb, Cs, Ti, Cr, Zr, etc; （2） the Zhucaohe section with thicker sediments and much bigger volcanic debris is far from the landderived region and close to the volcanically active area; while the Yang＇ erba section with much smaller volcanic ashes is far from the center of volcano activity area and close to the land-derived region and affected by certain land-derived debris; （3） the constraints of Cr/Co, Nb/Ta, Pd/Ir-Ni/Cu and Ni/Pd-Cu/Ir on magma quality indicate that the temporal magma is characteristic of basic basalts; and （4） the further constraints of La-Y-Nb and Th-Hf-Ta indicate that the temporal magma is characteristic of calc-alkaline island-arc volcanic basalts.

关 键 词：硅质岩 PGE 下寒武统 城巴地区 

分 类 号：P534.41[天文地球—古生物学与地层学] P536[天文地球—地质学]