ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    上扬子地区双河露头五峰组—龙马溪组下段化学层序地层分析

    Chemical Sequence Stratigraphy of the Wufeng Formation-lower Member of Longmaxi Formation in Shuanghe Outcrop, upper Yangtze

    • 摘要: 综合地球化学、高分辨层序地层学理论方法,利用双河露头资料及样品分析测试,采用多元统计方法优选出陆源输入强度相关元素组合Al-K-Ti-Mg-Rb-Cr-Zr、自生沉淀强度相关元素组合Ca-Mn-Ba-Co、有机质吸附及还原强度相关元素组合V-Ni-Mo-U-Cu-Zn作为化学层序地层划分指标体系,将双河露头五峰组划分为LCW四级层序,龙马溪组下段自下而上细分为MCL1-1、MCL1-2、MCL1-3、MCL1-4四级层序。陆源输入强度相关主微量元素组合总量在层序界面附近相对较高,而最大海泛面附近相对较低,具有元素总量减少-增加旋回性变化特征;而自生沉淀强度相关主量元素组合总量和微量元素组合总量、有机质吸附及还原强度相关微量元素组合总量在层序界面附近一般较低,在最大海泛面附近一般较高,具元素总量增多-减少旋回性变化特征。

       

      Abstract: Based on the theories and methods of comprehensive geochemistry and high resolution sequence stratigraphy, the data of Shuanghe outcrop and sample test are used to optimize the indicator system for the chemical sequence stratigraphic division.The division are the elements assemblages of Al-K-Ti-Mg-Rb-Cr-Zr related to terrigenous input intensity, the elements assemblages of Ca-Mn-Ba-Co related to autogenetic precipitation intensity, and the elements assemblages of V-Ni-Mo-U-Cu-Zn related to organic matter adsorption and deoxidation intensity. The Wufeng Formation is thus divided into LCW 4th-order sequence; and the lower part of Longmaxi Formation is divided into MCL1-1, MCL1-2, MCL1-3, MCL1-4 4th-order sequences accordingly from bottom to top. The total amount of major and trace element combinations related to the terrigenous input intensity is relatively high near the sequence boundary but relatively low near the most oceanic flooding surface, with the characteristics of decreasing-increasing cyclic changes of total elements. Autogenetic precipitation, organic matter adsorption and deoxidation intensity is generally lower near the sequence boundary and higher near the maximum flooding surface with the characteristics of increasing-decreasing cyclic changes of the total amount of elements.

       

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