羌塘盆地高精度航空重磁调查对盆地基底性质与构造格局的启示  

High-precision airborne gravity and magnetic survey analysis of the Qiangtang basin:implications for basin basement properties and tectonic framework

作　　者：周道卿 曹宝宝 赵睿[1] 胡悦 魏岩岩 肖梦楚 段宏伟 胡夏炜 郑宇舟 ZHOU Daoqing;CAO Baobao;ZHAO Rui;HU Yue;WEI Yanyan;XIAO Mengchu;DUAN Hongwei;HU Xiawei;ZHENG Yuzhou(China Aero Geoph ysical Survey and Remote Sensing Center for Natural Resources,Beijing 100083,China;Key Laboratory of Airborne Geo physics and Remote Sensing Geology,Ministry of Natural Resources,Beijing 100083,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国自然资源航空物探遥感中心,北京100083 [2]自然资源部航空地球物理与遥感地质重点实验室,北京100083 [3]中国地质大学地质过程与矿产资源国家重点实验室,北京100083

出　　处：《地质学报》2021年第11期3178-3191,共14页Acta Geologica Sinica

基　　金：中国地质调查局项目(编号DD20160065、DD20190025)资助的成果。

摘　　要：羌塘盆地是我国陆域面积最大的中生代海相沉积盆地,该盆地基底属性和深部构造特征尚未形成统一认识。最新获取的高精度航空重、磁资料发现北羌塘整体表现为"磁力高、重力低",南羌塘与之相反,并且北羌塘基底磁性明显强于南羌塘;基于航磁数据计算的基底深度显示出南、北羌塘具有明显差异,北羌塘基底深度普遍在7.0~15.0 km,凹陷中心多达6个;南羌塘基底深度稍浅,多在5.0~13.0 km,凹陷中心只有3个。南、北羌塘截然不同的重磁场特征表明羌塘盆地并不存在统一的前寒武系变质基底,南、北羌塘是两个完全不同的构造单元。E—W向的"中央隆起带"将羌塘盆地一分为二,使其整体呈现"两坳夹一隆"的构造格局,并可以进一步划分为31个凸起区和9个凹陷区。The Qiangtang basin is the largest Mesozoic marine sedimentary basin in China.However,a comprehensive understanding of the basement properties and deep structural characteristics of the basin is not yet available.The latest high-precision airborne gravity and magnetic data were used to constrain the basement properties and deep tectonic patterns of the Qiangtang basin.The gravity and magnetic field maps show that in contrast to the Southern Qiangtang block,the Northern Qiangtang block displays"high magnetic and low gravity field".Also,the magneticity of the basement in the Northern Qiangtang is significantly stronger than that of the Southern Qiangtang.In addition,the calculation results show that the basement of Northern Qiangtang depression is deeper,generally between 7.0~15.0 km,and there are 6 depression centers.The basement of the Southern Qiangtang depression is slightly shallower,mostly in 5.0~13.0 km,with 3 depression centers.The obviously differences in gravity and magnetic field indicate that there is no unified Precambrian basement in this basin,and the Northern and Southern Qiangtang blocks may be composed of completely different tectonic units.The consecutive central uplift belt divides the Qiangtang basin into two parts,presenting a structural pattern of"two depressions sandwiching one uplift".In this study,31 raised area and 9 sag areas were identified in the Qiangtang basin.

关 键 词：重磁场 基底 构造单元 羌塘盆地 

分 类 号：P631.2[天文地球—地质矿产勘探] P618.13[天文地球—地质学]