The 3D Electrical Structure Research On Northeast China Based On Array Regional Magnetotelluricmethod

This paper is on the subject "Experimental research of array type magnetotelluric standard network controlled framework on Northeast China(SinoProbe-01-04)" of the the first project"Mainland electromagnetic parameters of the standard network experimental study(SinoProbe-01)”of "Deep Exploration in China(SinoProbe)"(Mingsen Shang,2012),taking these as background.Based on the MT "standard points" of the graticule 4°×4° area electromagnetic parameters standard network controlled framework on Northeast of China,through data processing,analyzing the 3D electrical structures characteristic of Northeast China,combined with aeromagnetic,regional gravity,and seismic tomography and regional geology,structure information of the study area,study the lithosphere structure and area crust,deep structure characteristics of deep faults,the deep coupling relationship between each block,and dynamics mechanism of tectonic evolution in Northeast China.In this article,the lithosphere structure unit of Northeast China is divided into three large body:Xing Meng lithosphere block and Ji Hei lithosphere block,the north of north China block.Among them,Xing Meng lithosphere block can be further divided into two blocks:Erguna massif and Sing-an massif;Ji Hei lithosphere block can be further divided into three blocks:Song Nen massif and Jia Musi massif,Wan Dashan massif.From the research of array type magnetotelluric 2D and 3D electrical structure of the lithosphere on Northeast China,get the following conclusions:(1)On the overall performance,Longitudinal conductances are low in the north and south,high in the middle.SongLiao basin is high conductivity value,the north and south basin are low conductivity value;(2)The Great xingan mountains gravity gradient belt as dividing line,lithosphere is thicker in the middle and south of Great xingan mountains,than the west and north.The reason of thinning,may be due to the subduction of the Pacific plate,leading to lithospheric thickening,then delamination occurs,resulting in the thickness of lithosphere thinning in middle and north area of North China.Also may be due to the rift valley system of new generation stretch and tension.It is the outcome combining two mechanisms.At the same time,The magmatic process since Cenozoic,Also caused the lithosphere of Songliao basin performs high conductivity on the whole.