【作者】 张帆；

【导师】 魏文博；

【作者基本信息】 中国地质大学（北京） ， 地球物理学， 2013， 博士

【摘要】 论文依托“深部探测技术与实验研究”专项课题（SinoProbe-02-04），以全长大于2000km的大井-泉州超长大地电磁测深剖面数据为基础，采用Robust估计、远参考道处理、功率谱挑选等大地电磁测深数据处理技术，获得高质量的大地电磁测深频率响应，通过大地电磁测深三维正演模拟，研究海岸效应对近海地区大地电磁测深资料的影响，通过计算Swift和Bahr二维偏离度、相位张量、磁场感应矢量、电性主轴方位等参数对大地电磁测深剖面沿线区域的维性信息进行分析，维性分析表明大地电磁测深剖面数据整体二维性较好，通过二维非线性共轭梯度反演，获得青藏高原东北缘-华南壳、幔电性结构模型。对青藏高原东北缘-华南壳、幔电性结构模型分析研究表明，青藏高原东部电性结构具有纵向分层、横向分块的特征，纵向上大致可分为中、低阻-高阻-低阻-中、高阻4个电性层，华南地区的电性结构与青藏高原东部的电性结构差异较大，整体呈现出高阻特征，并具有横向分块和局部的纵向分层特征。青藏高原东部地区中、下地壳广泛发育有壳内高导层，以西秦岭北缘断裂带为界，南、北两侧大地构造单元的壳内高导层可能具有不同的成因机制。北侧祁连地块的壳内高导层可能是由于含盐流体的填充引起的，南侧西秦岭构造带和松潘-甘孜地块的壳内高导层可能是由于地壳内部岩石的局部熔融和含盐流体的填充两种因素共同作用引起的。华夏地块广泛分布有花岗岩，西部由于强烈的板内变形，可能在地壳内部形成了独特的构造-岩浆作用，中部在地幔热物质上涌和大陆伸展构造的联合作用下，可能出现了地壳内部的局部熔融现象，东部在太平洋板块向西俯冲的作用下，可能发生了强烈的壳、幔之间的物质交换和热流传输作用。龙门山断裂带地区的电性结构特征反映了青藏高原东部中、上地壳脆性物质沿高导的滑脱面产生的逆冲推覆构造，以及扬子地块楔入到青藏高原东部的中、下地壳和上地幔内部形成的楔入构造，逆冲推覆构造和楔入构造的共同作用可能是青藏高原东部地壳隆升的主要原因。更多还原

【Abstract】 Under the auspices of the SinoProbe-02-04, a long magnetotelluric profile whichis longer than2000km was acquired from the town of Dajing in the northeasternmargin of the Tibetan Plateau to the city of Quanzhou in South China. Many methodshave been used during the magnetotelluric data processing such as the robustestimation, the remote reference method and the editing of the power spectrum in orderto acquire the high quality magnetotelluric data. The effects of the ocean coast onmagnetotelluric data have been studied by three-dimensional electromagnetic forwardmodeling. The qualitative analyses of the electrical structure along the profile havebeen done by analyzing many parameters such as Swift skewness, Bahr skewness,phase tensor, magnetic induction vector, and direction of strike. Dimensionalityanalysis has shown a good two-dimensional character along the profile. Subsurfaceelectrical structure has been obtained through nonlinear conjugate gradients algorithmfor two-dimensional magnetotelluric inversion.The electrical resistivity model along the profile indicates that the electricalstructure in eastern Tibetan Plateau is characterized by four distinct layers in verticaldirection and block division in horizontal direction. The electrical properties betweeneastern Tibetan Plateau and South China are quite different. The electrical resistivity ishigh in South China. The electrical structure in South China is characterized by blockdivision in horizontal direction and distinct layering partially in vertical direction.There are the high-conductivity layers in the middle and lower crust in easternTibetan Plateau. The distribution of the high-conductivity layers in different blocks isbased on different formation processes. The high-conductivity layers in the crust underQilian block are likely due to the existence of saline fluids. The high-conductivitylayers in the crust under West Qinling orogeny and Songpan-Ganzi block are likelydue to the existence of partial melts and saline fluids.The granitic rocks are the main components of the continental crust in Cathaysiablock. There might be tectono-magmatism in the crust in western Cathaysia block due to continental intraplate deformations. Both upsurge of heat mantle materials andcontinental rifting might result in partial melts in the crust in central Cathaysia block.Delivery of thermal energy and interaction between crust and mantle in easternCathaysia block might be induced in the stage that Pacific plate subducted to theEurasian continent.The Longmenshan fault in the electrical resistivity model along the profilepresents the overthrusting between the eastern margin of the Tibetan Plateau and theYangtze block. The conductive layer in the range of mid to upper crust marks thedetachment surface under the Longmenshan nappe structure. The boundary betweenthe conductive Tibetan Plateau and the resistive Yangtze block has been shown belowthe conductive layer. The relationship between eastern Tibetan Plateau and Yangtzeblock might reflects the uplift mechanism of eastern Tibet Plateau.更多还原