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.

摘要： 鄂尔多斯地块西缘构造带的主要形式是逆冲推覆构造.逆冲推覆构造由推覆体系、前缘带、前缘外带和原地岩体四部分组成的.构造带主要成份是数条近南北延伸的逆冲断层,断面西倾向东逆冲,推覆距离20～40千米.断面上陡下缓,深部近于水平,并沿石炭系和二叠系煤系地层滑脱.地面见多处飞来峰.由于主要断裂走向的变化,构造带从北而南分为四段.各段有其各自的特征.该区是鄂尔多斯地块最有利的勘探地区之一,其沉积岩厚,生储油岩好,圈闭类型多.油气勘探的关键问题是生油岩的成熟度和油气的保存条件.作者认为,原地岩体和前缘外带保存条件好,演化程度高.罗山-马家滩段的原地岩体和构造带北段的前缘外带是石油勘探的最有利地区.

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