Study Of Lithosphere Conductive Structure Of North Ordos Block

Ordos block is located in the western part of the North China plate, it played animportant role in tectonic activity of the North China plate from Cenozoic era，andits tectonic activity and dynamics studies has been subject to the attention of themajority of geoscientists.This thesis is based on the deep detection technology andexperimental research projects“sinoprobe-01-02”，Selected magnetotelluric data getfrom northern Ordos Basin and its adjacent areas, specific scope E104°-E111°，N38°-N41°region, selected L38, L39, L40, L41sections along the longitudedirection。Through the skewness analysis and impedance tensor decomposition, the paperidentified the study area can be considereda two-dimensional structure of aNNE-trending。 The paper did one-dimensional, two-dimensional andthree-dimensional inversion. One-dimensional inversion method is the Bostickmethod and OCCAM method; the two dimensional inversion method is NLCGmethod, by different inversion mode and inversion parameter model comparison, weconsidered that the model with TM mode and tau=10is the best；three-dimensionalinversion method is the code from Bangkok University Professor WeerachaiSiripunvaraporn code (WSINV3DMT)。Three inversion methods are able to reflectthe “low-high-low” layered conductive structure model of the earth.Through the analysis of the inversion results，the paper divided the mainelectrical interface of the study area that the crustal thickness in the range of40-45km,the lithosphere thickness in the range of120-150km.Ordos block developed lots ofhigh-conductor，the shallow layers were the sedimentary cover with low resistancecharacter，the high-conductor in the lower crust was caused by saline fluids and thesaline fluids was prevented by a rigid “cap”,the exist of the cap in turn proved thatOrdos block was a stable block. The periphery of Ordos block developed lots of faults，the fault damaged the high-resistance stratum and change the distribution of the salinefluids。So，in the periphery of Ordos block，the development of the high-conductivitywas massive distribution, layering is not obvious.