云南地区深部电性结构特征

Characteristic of deep electrical structure in Yunnan region

收集了云南省5条重要大地电磁测深(MT)剖面资料,并加以分析研究,划分6个地块;中甸地块在地壳内存在低阻带(层),推断由低阻管流通道引起,并存在地幔柱;腾冲地块在地壳内存在低阻体,推断由岩浆囊引起;保山地块存在壳-幔低阻带,推断由上地幔隆起产生壳-幔熔融物质引起;兰坪-思茅地块在地壳内横向整体呈低—高—低电性结构特征,推断地块中心区上地幔的基性和超基性幔源隆起引起高阻,隆起区顶两侧岩浆熔融引起低阻;扬子地块(云南部分)在地壳内存在低阻带(层),推断与主要与断裂(带)活动构造有关;华南地块(云南部分)大地电磁测深剖面涉及很小区域,缺乏代表性,没有分析研究.

Five important Magnetotelluric Sounding(MT)profiles data of Yunnan region were collected and analyzed,and six blocks were divided.There were low resistivity zones(layers)in the crust of Zhongdian block,inferring to be caused by low resistivity pipelines and mantle plumes.There were low resistivity bodies in the crust of Tengchong block which maybe induced by the Magma sacs.Low resistivity zones exited in the crust and mantle of Baoshan block,inferringto be caused by melting material because of the uplift of upper mantle.The Lanping-Simao block was characterized by low-high-low electrical structure in the transverse direction of the crust,and itcould be inferre that the uplift of the basic and ultrabasic upper mantle in the central area of the block caused high resistivity,and the melting of magma on both sides of the uplift area caused low resistivity.There were low resistivity zones(layers)in the crust of Yangzi block(Yunnan),which was inferred to be related to active structures of major faults(zone).Magnetotelluric sounding profiles of South China Block(Yunnan)involved a small area,which lacked ofrepresentation,so it wasn’t analyzed.