四川盆地峨眉山雷口坡组底部黏土岩(绿豆岩)的年代学及地球化学特征  

Geochronological and Geochemical Characteristics of the Claystone ( Mung Bean Rock)at the Bottom of the Leikoupo Formation in the Emeishan Area,Sichuan Basin,China

作　　者：李宸 郎兴海 邓煜霖 王旭辉 李壮 杨宗耀 LI Chen;LANG Xing-hai;DENG Yu-lin;WANG Xu-hui;LI Zhuang;YANG Zong-yao(College of Earth Science,MNR Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,China;School of Geography&Resource Science,Neijiang Normal University,Neijiang Sichuan 641100,China;Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 611756,China)

机构地区：[1]成都理工大学地球科学学院,国土资源部构造成矿成藏重点实验室,成都610059 [2]西北大学大陆动力学国家重点实验室,西安710069 [3]内江师范学院地理与资源科学学院,四川内江641100 [4]西南交通大学地球科学与环境工程学院,成都611756

出　　处：《矿物岩石地球化学通报》2020年第4期810-825,共16页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：大陆动力学国家重点实验室开放课题(18LCD04);国家自然科学基金资助项目(41972084);四川省杰出青年科技人才项目(20JCQN0139)。

摘　　要：四川盆地峨眉山地区中三叠统雷口坡组底部发育了一层特殊的黏土岩(绿豆岩),为确定其形成时代和成因,对其进行了锆石U-Pb定年、X射线衍射分析及主、微量元素含量测试。结果表明,黏土岩(绿豆岩)的锆石U-Pb年龄为(247.6±1.1) Ma,代表了峨眉山地区雷口坡组底部黏土岩的形成年龄。镜下及X衍射特征表明黏土岩的主要矿物为伊利石,另含有少量方解石和石英。主、微量元素分析表明,黏土岩具有长英质火山岩的特征,可能与当时的华南酸性岩浆活动有成因联系。综合分析认为,该套黏土岩(绿豆岩)是由华南火山活动形成的中酸性火山物质漂移搬运至沉积盆地,在富K、Li等元素的盆地卤水作用下,经埋藏成岩作用而形成的。In order to explore the age and petrogenesis of the claystone(mung bean rock)at the bottom of the Middle Triassic Leikoupo formation in the Emeishan area,Sichuan basin,the zircon U-Pb dating,X-ray diffraction,and major and trace elemental geochemical analysis of the claystone have been carried out in this study.The results show that the U-Pb age of(247.6±1.1)Ma for zircons from the claystone(mung bean rock)represents the formation age of the claystone at the bottom of the Leikoupo formation in theEmeishan area.The features of microscopy and X-ray diffraction show that the claystone is mainly composed of illite,with minor calcite and quartz.The results of major and trace element analyses show that the claystone has characteristics of the felsic volcanic rock,which could be genetically related to the acidic magmatic volcanic activity in South China at that time.Based on the comprehensive analysis,it is believed that the claystone(mung bean rock)could be formed by burial diagenesis of materials which were firstly transported to the sedimentary basin from intermediate-acidic volcanic materials of volcanic activities in South China,and then were interacted with the basin brine enriched in K,Li,and other elements.

关 键 词：黏土岩 锆石U-PB年代学 地球化学 雷口坡组 峨眉山地区 

分 类 号：P588.22[天文地球—岩石学]