The Relationship Between Geophysical Field Features And Sandstone-type Uranium Deposits In The West-south Of Ordos Basin

Ordos basin,located in the west of North China Platform,is a Mesozoic Basin with lots of prtroleum,gas,caol,uranium and other mines,which is formed after many tectonic movements and sedimentary evolutions.Our study area is the southwest part of Ordos basin,where has been found sevral uranium deposits and has good exploration prospect.However,the geological and geophysical studies for this area are insufficient.Therefore,by analyzing the observed materials of gravity and magnetism and discussing the temporal and spatical relationship between geophysical fields and uranium deposits,this dissertation aims to provide geophysical basis for uranium mine exploration in this area.Our study methods mainly include collecting the gravity and magnetic material of the southwest part of Ordos basin,determining the position of discovered uranium mines,combining the previous research results and data processing of gravity and magnetic materials with RGIS software.And then,we interpret the geophysical fields of gravity and magnetic abnormal distribution and use these results to deduce faults structures and the effects of magnetic bodies on uranium mine.Further,with seismic and logging data,we choose two profiles to invert gravity field,and analyze the quantitative and qualitative relationship of geological layers and uranium mine position.At last,we construt the temporal and spatical relationship of gravity and magnetic abonormal fearures and uranium mine distribution.The study results show that the faults trends mainly include NE,EW,SN and NW,of which F1,F2 and F3 control the distribution of uranium mine,the intersections of main faults and secondary faults are the position of found uranium mine,the ancient rocks with strong magnetism is the main uranium source rocks,uranium are found in stable layers.The plane distribution features of uranium mines are that they are located in both sides of main faults and the intersections of main faults and secondary faults,uranium deposits are distributed in the aera of transition region from high gravity to low gravity,there are many magnetic bodies with different scales in the transition region from high magnetic to low magnetic aeras.Our study could provide guidance for uranium mines prediction and the prospecting regions are Pingliang,Yijun-Huangling,Binxian-Xunyi.