扬子地台北缘中上二叠统层状硅质岩的地球化学特征及其对古地理、古海洋演化的响应  

Geochemical Characteristics of the Middle-Upper Permian Bedded Cherts in the Northern Margin of the Yangtze Block and Its Response to the Evolution of Paleogeography and Paleo-Ocean

作　　者：程成[1] 李双应[1] 赵大千 颜玲[3] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]山东黄金有色矿业集团有限公司,济南250000 [3]安徽省地震局,合肥230031

出　　处：《矿物岩石地球化学通报》2015年第1期155-166,共12页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金(41172097;40972082)

摘　　要：为探讨华南地区二叠纪硅质岩的硅质来源和形成背景,本文以扬子地台北缘中上二叠统孤峰组和大隆组层状硅质岩为研究对象,对采自孤峰组和大隆组层状硅质岩样品进行了主量元素、微量元素和稀土元素分析测试,同时收集了大量前人有关孤峰组和大隆组的资料。上述研究结果表明,孤峰组和大隆组层状硅质岩的Al/(Al+Fe+Mn)、Si/(Si+Al+Fe)平均值分别为0.57、0.91和0.48、0.97,结合Al-Fe-Mn三角图解,指示它们主要为生物成因;其Ce/Ce*、(La/Ce)N和(La/Yb)N平均值分别为0.86、1.58、1.27和0.75、1.52、1.46,结合沉积环境判别图,表明其沉积环境均主要为大陆边缘,推测硅质岩的形成可能与上升流的活动有关。部分地区存在热水成因硅质岩和/或受热水影响硅质岩并往往沿同沉积断裂分布,暗示同沉积断裂可能为热水活动提供通道。To discuss the origin and sedimentary background of chert in South China,we took the bedded cherts in Gufeng and Dalong Formations which locate in the northern margin of the Yangtze block as examples. In this study,we collected extended literature data about these two formations and systematically analyzed major,trace and rare earth elements contents of cherts collected from the formations. The average values of Al /（Al ＋ Fe ＋ Mn） and Si /（Si ＋ Al ＋ Fe） ratios for Gufeng and Dalong Formations are 0. 48 and 0. 97,and 0. 57 and 0. 91,respectively,which combined with plots of Al-FeMn of cherts indicated that they are mainly biogenic cherts. The average values of Ce/Ce＊,（La/Ce）Nand（La/Yb）Nfor Gufeng and Dalong Formations are 0. 86,1. 58 and 1. 27 and 0. 75,1. 52 and 1. 46,respectively,which combined with diagrams of sedimentary environments suggested that they were mainly deposited at continental margins. According to their origin and sedimentary background,we concluded that formations of the cherts were more likely associated with activities of upwelling. The hydrothermal chert and chert influenced by hydrotherm tended to distribute along the syndepositional faults in some areas,which may implied that syndepositional faults provided channels for the hydrotherms.

关 键 词：硅质岩 地球化学 上升流 热水沉积 中上二叠统 扬子地台北缘 

分 类 号：P588.244[天文地球—岩石学] P534.46[天文地球—地质学]