新疆41°N88°E大地电磁标准点深部电性结构初步研究  

Preliminary Study on Deep Electrical Structure at the Magnetotelluric Standard Point 45°N88°E Region in Xinjiang

作　　者：胡祥云[1] 李永洲[1,2] 彭荣华[1] 霍光谱[3] 

机构地区：[1]中国地质大学地球物理与空间信息学院,湖北武汉430074 [2]中石油煤层气有限责任公司,北京100028 [3]河南省地质调查院,河南郑州450001

出　　处：《工程地球物理学报》2014年第3期277-285,共9页Chinese Journal of Engineering Geophysics

基　　金：国家深部专项(编号:SinoProbe-02);国家自然科学基金项目(编号:41274077)联合资助

摘　　要：近年来,大地电磁（MT）在揭示壳幔电性结构、深部找矿和油气勘探等方面正发挥着举足轻重的作用。本文所研究的41°N88°E标准点位于塔里木盆地的东北部区域和天山板内造山带的南侧。通过采用RRI反演方法对不同模式的MT数据进行了反演研究,获得了研究区域内可靠的二维电性结构。结合区内地质和其它物探资料,探讨了该地区的地下电性结构变化特征及其地质意义。根据41°N88°E号标准点地区NS剖面和WE剖面的反演结果,该区域纵向上存在两个起伏较大的电性分界面;整个剖面可分为3个主电性层：第一电性层为表层低阻层;第二电性层为壳内高阻层,包括两个沿剖面不连续分布的区块,规模和埋深有很大差别,整体具有北薄南厚和东薄西厚的特征;第三电性层表现为中低阻特征,位于莫霍面以下。东部的却尔却克构造岩片下有一低阻区域,推测为软流圈隆起使塑性的软流圈物质上涌到较浅的位置从而形成了高导层。研究区莫霍面深度起伏较大,总体上呈现出北浅南深和东浅西深的趋势。其中库鲁克塔格断隆地区莫霍面深度较浅约为35km左右,带有上凸的趋势;孔雀河斜坡区莫霍面深度在50~55km,带有下凹形状。In recent years,magnetotellurics has played an increasingly important role in the study of electrical structure of the crust and upper mantle,deep mineral exploration,oil and gas exploration and other fields.The magnetotelluric standard point 41°N88°E region of this paper is located between the northeast area of the Tarim basin and the south of theTianshan orogenic belt.The two-dimensional（2D）electrical structure of the studying region is obtained by using a RRI inverse scheme.Based on known geological and other geophysical data of this region,the subsurface consists of three distinct electrical layers.The first layer is characterized by high conductivity extending down to about 15km depth;the second layer ranging from 30to 60km in depth consists of two discontinuous resistive domains whose scales and depths vary greatly;while the third layer below the Moho shows medium resistivity,the eastern domain of which below the Queerqueke tectonic slice is highly conductive.This may be plastic asthenospheric materials in lower crust due to asthenospheric bump.The depth of Moho in this region varies greatly along NS or WE profiles,The depth of Moho in the Kuruktag fault uplift is about 35km with a convex trend,while the depth of Moho in the Kongquehe slope is 50~55km with a concave trend.

关 键 词：大地电磁测深 电性结构 电阻率 二维反演 

分 类 号：P631.3[天文地球—地质矿产勘探]