柴达木盆地西部岩石圈电性结构研究  

Lithospheric electrical structure of western Qaidam Basin

作　　者：徐盛林[1,2] 邵兆刚 李冰[1,2] 陈宣华 王振东[3] 徐大兴 马英[3] 丁伟翠 周鹏超 王叶 XU Shenglin;SHAO Zhaogang;LI Bing;CHEN Xuanhua;WANG Zhendong;XU Daxing;MA Ying;DING Weicui;ZHOU Pengchao;WANG Ye(Chinese Academy of Geological Sciences,Beijing 100037,China;SinoProbe Laboratory,Ministry of Natural Resources of China,Beijing 100037,China;Qinghai Geological Survey,Xining 810001,Qinghai,China)

机构地区：[1]中国地质科学院,北京100037 [2]自然资源部深地科学与探测技术实验室,北京100037 [3]青海省地质调查局,青海西宁810001

出　　处：《地质通报》2024年第11期1907-1920,共14页Geological Bulletin of China

基　　金：中国地质调查局项目《深部地质调查》(编号:DD20230008);《西北重要构造廊带深部地质调查》(编号:DD20230229);青海省地质勘查专项基金项目《柴达木盆地西部构造体系与中新生代构造演化研究》(编号:2023085027ky002-1)。

摘　　要：柴达木盆地油气、矿产等资源丰富,其成因演化、物质组成和深部结构特征在青藏高原地质研究中更是举足轻重。大地电磁测深作为研究岩石圈电性结构的重要方法之一,可以为盆地动力学、资源勘查、矿床成因研究等提供重要支撑。在柴达木盆地西部的油泉子—花海子地区,布设了一条长约255 km的(超)宽频大地电磁测深测线,并获得二维反演剖面,结合区域地质资料和已有的地球化学、地球物理等研究成果,初步分析了研究区岩石圈尺度各重点电性层的构造意义。柴达木盆地西部新生界发育上、下2个变形强度不同的电性层,上部变形较弱的电性层含一套低于2Ω·m的超低阻层,与盆地深层优质卤水层对应,指示了良好的深层卤水找矿前景;下部电性层变形较强烈,底部可见一套生长电性层,推测盆地深部存在的主柴达木拆离断层在新生代控制了盆地的新生界沉积与构造变形。研究区深部电性结构差异明显,深部约50 km处有一条高低起伏的电性莫霍面,柴达木和苏干湖盆地深部以中低阻体为主,赛什腾山地区为有根的高阻体,油泉子—碱山地区中—下地壳为一套低阻体,昆特依地区深部可能存在软流圈物质的上涌。The Qaidam Basin is rich in oil,gas,and mineral resources.Its origin and evolutionary process,composition,and deep structural characteristics play a crucial role in geological research on the Qinghai−Tibetan Plateau.Considering that magentotelluric sounding as one of the vital methods to study the electrical structure of the lithosphere,it can provide significant support for basin dynamics,resource exploration and deposit genesis research.To better analyze the tectonic significance of the key electrical layers in the lithosphere of the Qaidam Basin,we conducted a(ultra-)broadband magnetotelluric sounding line about 255 km long from the Youquanzi to the Huahaizi in the western Qaidam Basin,which obtained a 2D profile,and including the combination with regional geological,the existing geochemical and geophysical research results.In the western Qaidam Basin,two Cenozoic electrical layers with different deformation strength developed in the upper and lower strata.The upper electrical layers with weak deformation contains a set of ultra-low resistivity layers lower than 2Ω·m,which corresponds to the high-quality brine layer in the deep basin,indicating a good prospect of deep brine prospecting.But the deformation of the lower electrical layer is relatively strong,and a set of growing electrical layer can be seen at the bottom.We considered that the existence of the main Qaidam detachment fault in the deep part controlled the Cenozoic sedimentary and tectonic deformation of the basin at the beginning of the Cenozoic.There are significant differences in the deep electrical structure of the research area,with a high and low undulating electrical Moho surface located about 50 kilometers deep.The deep parts of Qaidam Basin and Suganhu Basin are dominated by medium−low resistance bodies.The Saishiteng Mountain area is rooted with high resistivity body,while the middle and lower crust of the Youquanzi alkali mountain area is a set of low resistance bodies.There may be an upwelling of asthenosphere material in the deep

关 键 词：柴达木盆地西部 赛什腾山 大地电磁测深 电性结构 深层卤水找矿 

分 类 号：P31[天文地球—固体地球物理学] P631.325[天文地球—地球物理学]