下扬子巢湖地区二叠系栖霞组硅质结核地球化学特征与成因研究  

Geochemical characteristics and genesis of siliceous nodulesof Permian Qixia Formation in the Lower Yangtze Terrace,Chaohu District

作　　者：王跃 张金龙[3] 周奇明 陈岳龙[1] 李大鹏[1] 康欢[1] WANG Yue;ZHANG Jinlong;ZHOU Qiming;CHEN Yuelong;LI Dapeng;KANG Huan(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;China Nonferrous Metals(Guilin)Geology and Mining Co.,Ltd.,Guilin 541004,Guangxi,China;Shixi Oilfield Operation Area,Xinjiang Oilfield Company,Karamay 834000,Xinjiang,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国有色桂林矿产地质研究院有限公司,广西桂林541004 [3]新疆油田公司石西油田作业区,新疆克拉玛依834000

出　　处：《矿产与地质》2020年第1期91-100,共10页Mineral Resources and Geology

基　　金：国家重点研发计划项目(2016YFC0600608)资助。

摘　　要：在野外地质调查的基础上,对下扬子巢湖地区二叠系栖霞组硅质结核地球化学特征进行了系统的分析。结果表明:下扬子巢湖地区二叠系栖霞组硅质结核核w(SiO 2)为73.50%~96.95%(平均值为85.84%),其他元素含量较低。在主量元素的判别上,硅质成因为生物质成因;在Ti/V-V/Y判别图解中,巢湖地区栖霞组硅质结核来源于洋中脊与大洋盆地端元区域;在元素氧化还原关系上,硅质结核显示出有氧、贫氧与厌氧混合状态;在稀土元素配分图解中,显示出中稀土元素富集,稀土元素总量与P 2 O 5具有很好的相关性和Ce的负异常。在此基础上,结合二叠纪全球气候与海陆位置及洋流的关系,认为下扬子巢湖地区二叠系栖霞组硅质结核是在二叠纪全球气候转变的背景下,在洋流的作用下,来源于大洋中脊与大洋盆地的硅质被大陆边缘的硅质生物捕获而形成硅质结核,洋流作用在硅质结核的形成上起到关键作用。Based on the field geological survey,the geochemical characteristics of silicic nodules in Permian Qixia Formation in the Lower Yangtze Terrace are systematically analyzed.The result shows that the SiO 2 content of siliceous nodules is 73.50%–96.95%(average:85.84%)in Permian Qixia Formation within Chaohu area,and the contents of other elements are lower.In the discriminant of the main elements,the genesis of siliceous nodules is biomass type.In the Ti/V-V/Y discriminant diagram,the siliceous nodules of Qixia Formation in the Chaohu area is derived from the mid-ocean ridge and the end zone of ocean basin.On the redox relation of elements,the siliceous nodules show the mixed state of aerobic,anaerobic and anaerobic states.In the rare earth element distribution diagram,it shows the enrichment of middle rare earth elements,ΣREE has a good correlation with P 2 O 5 content and the anomaly of Ce is negative.On this basis,combined with the relationship between the Permian global climate and the location of the sea and land and ocean currents,it is believed that the siliceous nodules of Permian Qixia Formation in the lower Yangtze Terrace within Chaohu area are under the background of global climate change in the Permian period.In the ocean currents,silica from the mid-ocean ridge and ocean basin is captured by siliceous organisms on the continental margin to form siliceous nodules.The ocean current plays a key role in the formation of siliceous nodules.

关 键 词：硅质结核 二叠系 栖霞组 地球化学特征 洋流作用 巢湖地区 

分 类 号：P588.244[天文地球—岩石学]