关键词: 构造特征, 原地岩体, 鄂尔多斯地块, 鄂尔多斯西缘, 构造带, 推覆体, 保存条件, 逆冲推覆作用, 逆冲推覆构造, 前缘带

Abstract: The main type of the west margin tectonics belt of the Ordos massif is characterised by thrust nappe.The over thrust nappe consists of four parts:nappe system,front zone,outer front zone and autochthon.The structural belt consists of many major thrust faults extended north-south approximately.The fault plane inclined towards west and over thrusted towards east,with an over thrust distance of 20-40m.The fault plane mainly slided along the coal-bearing formation in Carboniferous system and Permian system,with high dip angle at the upper part,low angle at the lower part and it is approximately horizontal in the depth.Klippen are found at many places on the ground surface in the region.Because strikes of the main thrust fault is changed,the belt is divided into four section from the north to the south.Each of the sections has its own structural features.This belt is one the most favouravle areas for the exploration of oil and gas in Ordos massif due to its thick sediments,better source rocks and reservoir rocks,and the pressure of various types of traps.The key to the oil and gas exploration is the maturity of the source rocks and the preservation of the oil and gas.The author states that the autochthons and outer front zones have better preservation condition and higher maturity of the source rock.The autochthons of the Lousan-Majiatan section and the northern part of the outer front zone of structural belt are most favourable for oil and gas exploration.