安徽省巢湖地区二叠纪栖霞组、孤峰组硅质岩地球化学特征对比及大地构造背景分析

发布时间：2018-06-29 23:33

本文选题：硅质岩 + 海盆　；参考：《现代地质》2017年04期

【摘要】：为探讨下扬子地区二叠系硅质岩的硅质来源和形成背景,以巢湖地区二叠纪栖霞组和孤峰组硅质岩为研究对象,收集了前人大量有关栖霞组和孤峰组的研究成果和数据,并对采自栖霞组和孤峰组硅质岩样品进行了主量元素、微量元素、稀土元素测试。栖霞组、孤峰组硅质岩样品测试结果显示,硅质岩的稀土元素经北美页岩标准化后的配分曲线近似平坦型向左倾斜,有弱Ce负异常,且HREE弱富集,反映了热水沉积硅质岩的特征。研究区硅质岩样品的Al-FeMn三角图中,样品投点分布较广,即Al比值变化范围较大,认为是岩浆在喷发过程中受硅-铝质陆壳混染作用的结果。结合沉积环境判别指标分析认为:栖霞组硅质岩沉积时期其沉积环境主要为大陆边缘环境;孤峰组硅质岩沉积时期其沉积环境为大陆边缘-海盆过渡环境。从栖霞组到孤峰组沉积时期,海侵规模不断变大,水体变深,海盆面积扩大,研究区在不同时期沉积环境存在差异。研究区栖霞组、孤峰组硅质岩的沉积与大陆边缘裂陷活动紧密相关。
[Abstract]:In order to study the origin and formation background of the siliceous rocks of the Permian in Lower Yangtze area, taking the Qixia formation and the Gufeng formation of the Permian in Chaohu area as the research objects, a great deal of research results and data of Qixia formation and Gufeng formation have been collected. The main elements, trace elements and rare earth elements of siliceous rock samples collected from Qixia formation and Gufeng formation were tested. The samples of siliceous rocks from Qixia formation and Gufeng formation show that the rare earth elements of siliceous rocks are approximately flat and inclined to the left through the normalized distribution curve of North American shale, with weak ce negative anomalies and weak HREE enrichment. It reflects the characteristics of hydrothermal sedimentary siliceous rocks. In the Al-FeMn triangle diagram of siliceous rock samples in the study area, the distribution of the sample input points is relatively wide, that is, the Al ratio varies in a large range, which is considered to be the result of the magma being mixed by silicon-aluminite continental crust during the eruption process. Based on the discriminant analysis of sedimentary environment, it is concluded that the sedimentary environment of siliceous rocks in Qixia formation is mainly continental margin environment, and that of siliceous rock in Gufeng formation is the transitional environment between continental margin and oceanic basin during the sedimentary period of Gufeng formation. From Qixia formation to Gufeng formation, the scale of transgression becomes larger, the water body deepens, and the basin area expands. The sedimentary environment of the study area is different in different periods. The deposition of siliceous rocks in Qixia formation and Gufeng formation in the study area is closely related to the continental margin rifting activity.
【作者单位】：中国石油大学(华东)地球科学与技术学院;中国有色金属工业昆明勘察设计研究院有限公司;
【基金】：国家自然科学基金项目(41272123) 中央高校基本科研业务费专项资金项目(13CX06016A)
【分类号】：P548;P588.244

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