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下扬子区二叠系层序地层的地球化学特征

杜小弟 黄志诚 陈智娜 刘家润   

  1. 南京大学地球科学系
  • 收稿日期:1996-09-20 修回日期:1996-09-20 出版日期:1996-09-20 发布日期:1996-09-20

GEOCHEMICAL CHARACTERISTICS OF PERMIAN SEQUENCE IN LOWER YANGTZE REGION

Du Xiaodi, Huang Zhicheng, Cheng Zhina, Liu Jiaren   

  1. Department of Earth Sciences, Nanjing University
  • Received:1996-09-20 Revised:1996-09-20 Online:1996-09-20 Published:1996-09-20

摘要: 本文以安徽巢县平顶山、鬼门关剖面为例,阐述了二叠系沉岩的主要岩石类型,即灰岩、硅质岩和泥质岩的岩石学特征及稀土元素组成特点;划分出七种沉积相类型,即局限台地相、开阔台地相、斜坡相、盆地相、三角洲相、汪 相和陆缘泻湖相;识别出七个Ⅲ级层序,其中四个为Ⅰ型层,三个为Ⅱ型层序。对栖霞组灰岩的地球化学测试数据进行了统计分析,总结了海侵体系域,高水位体系域的氧碳同位素、稀土元素和微量元素组成的差异,并认为造成差异的原因是海平面升降变化对氧、碳同位素、稀土元素和微量元素的影响机理不同所致。

Abstract: Permian in Lower Yangtze Region is a typical sequence of mixed carbonate, chert and terrigenous clastics. Taking the Permian profiles in Chaoxian, Anhui as examples, the authors discuss its petrological and REE distribution characteristics. Seven sedimentary facies are divided, namely: restricted platform, open platform, continental slope, basin, delta, neritic and continental marginal lagoon facies, The Permian can be divided into seven third-order sequences. Four of them are type I sequences, other three agre type II sequences. Then the authors elaborate geochemical characteristics of these sequences. With the rising of sea level, δ13C is gradually increased and δ18O decreased. When sealevel changed, the high stand systems tract (HST) and the trangresivestand systems tract (TST) have different REE compositions. The total REE of TST is greater than that of HST. The trace element distribution characteristics in TST is different from that of HST. Based on above work, the authors conclude that geochemical parameters such as O and C isotopes, REE and trace elements are helpful to sequence analysis.