拉萨地块中二叠统洛巴堆组岩石磁学及其地质意义  

Magnetic characteristics of rocks and geological significance in the Middle Permian Luobadui Formation,Lhasa block,Tibet

作　　者：幸龙云 吴汉宁[1] 周亚楠[1] 卫弼天 姜南 吴珂 张伟杰 陈庆龙 王保锋 许鹏祥 兰书琪 李腾 张冬孟 邓晓红 刘非凡 武景岳 王嘉伟 程鑫[1] XING LongYun;WU HanNing;ZHOU YaNan;WEI BiTian;JIANG Nan;WU Ke;ZHANG WeiJie;CHEN QingLong;WANG BaoFeng;XU PengXiang;LAN ShuQi;LI Teng;ZHANG DongMeng;DENG XiaoHong;LIU FeiFan;WU JingYue;WANG JiaWei;CHENG Xin(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China;Department of Ocean Science and Engineering,Centre for Marine Magnetism(CM2),Southern University of Science and Technology,Shenzhen 518055,China;College of Petrol and Environmental Engineering,Yan'an University,Yan'an 716000,China;Gansu Provincial Coal Geological Exploration Institute,Lanzhou 730000,China)

机构地区：[1]西北大学地质学系/大陆动力学国家重点实验室,西安710069 [2]南方科技大学海洋科学与工程系,海洋磁学中心(CM2),深圳518055 [3]延安大学石油学院,延安716000 [4]甘肃煤炭地质勘查院,兰州730000

出　　处：《地球物理学进展》2023年第4期1517-1530,共14页Progress in Geophysics

基　　金：国家自然科学基金特提斯地球动力系统重大研究计划重点项目(91855211);国家自然科学基金面上项目(41774073,42074075);国家自然科学基金青年项目(41702233)联合资助。

摘　　要：拉萨地块是研究班公湖—怒江特提斯洋和雅鲁藏布江特提斯洋演化过程的关键,但印度—亚洲大陆的碰撞可能导致拉萨地块遭受不同程度的重磁化影响,为寻找理想地层进行古地磁研究,本文对拉萨地块中二叠世洛巴堆组砂岩、火山岩及灰岩样品进行详细的岩石磁学研究,以确定各类岩石是否具备记录原生剩磁信息的能力.结果表明砂岩样品中主要载磁矿物为磁黄铁矿,火山岩及灰岩样品中主要为磁铁矿或赤铁矿.结合区域地质资料和部分样品退磁实验,本文认为砂岩样品可能遭受林子宗群火山和岩浆活动所提供的区域热扰动影响,记录了古近系重磁化信息;火山岩和灰岩样品可能记录了岩石形成时期的原生剩磁信息,有望从中获得可靠古地磁数据.The Lhasa terrane is the key to study the evolution of the Bangong Co-Nujiang Tethys Ocean and the Yarlung-Zangbo Tethys Ocean.However,India-Asian continental collision may partly re-magnetize the Lhasa block.In this paper,in order to find suitable strata for paleomagnetic research and determine whether various rocks have the ability to record the primary remanence magnetism information,we carry out a detailed rock magnetic research on the sandstone,volcanic rock and limestone samples of the Middle Permian Luobadui Formation,Lhasa block.The results indicate that the main magnetic carriers in sandstone are pyrrhotite,and volcanic rock as well as limestone are magnetite or hematite.Combining with regional geological data and demagnetization experiments of some samples,we believe that the sandstone samples,have been affected by the regional thermal disturbance caused by the volcanic and magmatic activities of the Linzizong Group,may record the information of re-magnetization in the middle Paleogene;the volcanic rock and limestone samples may record the primary remanence magnetism information of rock formation,which is expected to obtain reliable paleomagnetic data.

关 键 词：拉萨地块 岩石磁学 古地磁学 重磁化 洛巴堆组 

分 类 号：P318[天文地球—固体地球物理学]