Abstract: The foreland basins of the Mesozoic and Cenozoic in mid-western area of China are located in the eastern end of Northern Basin groups of Tethys tectonics.The forming of foreland basin was controlled by the revolution of Tethys Tectonics.Two epochs of foreland basins were developed in mid-western China during the Early Mesozoic and the Late Cenozoic respectively. Foreland basins may be divided into three types and four kinds of responding foreland basins (or thrust belts).All of those foreland basins were controlled by the evolution of Thetys tectonics.Two epochs of foreland basins both underwent the tension tectonics.The tectonics environments of the foreland basins formed the specific geological characteristics for natural gas.Effective resource rock was grown in the tension tectonics settings.Foreland thrust belts were developed in the compression tectonics settings.The foreland was well match with the trapping time and space in the large rowed and belted structural traps.The early foreland basin and thrust belt were altered and superposed by the structures of the late foreland basin.The traps in the main body of the early foreland basin almost were seriously damaged,and the traps in the thrust frontier,fore-deep and fore-bulge slopes and uplift of the early foreland basin could be well preserved.For the late foreland basin,the large structural traps in the thrust belt and fore bulge have some good conditions for pooling gas and will be the key exploration targets recently.

Key words: China’s mid-western areas, foreland basin, foreland thrust belt, Thetys tectonics, natural gas geology

摘要： 前陆盆地是指呈线性收缩于造山带和克拉通之间、由造山带逆冲负荷引起挠曲并沉降成狭长的沉积单元。中国中西部中新生代前陆盆地都处于特提斯北缘盆地群东端,其形成主要受特提斯演化控制。中生代以来,中国中西部地区分别在中生代早期、新生代晚期发育两期前陆盆地,又被分为3类、4种相应的前陆盆地(前陆逆冲带),主要由前陆盆地早期拉张环境下的细粒沉积物或碳酸盐岩和前陆挤压期的粗粒沉积物叠置而成,成为前陆盆地特有的二元结构。发育了前陆盆地特有的天然气地质特征,即拉张构造背景下沉积有效的烃源岩层系、挤压背景下发育前陆逆冲带、喜山期形成成排成带的大型圈闭。早期前陆逆冲带被后期构造改造叠加,主体部位构造圈闭破坏严重,冲断带前锋、前渊、前缘斜坡和隆起部位圈闭保存较好;晚期前陆逆冲带与前缘隆起构造圈闭发育,成藏条件好,是近期勘探的主攻目标。

关键词: 中国中西部, 前陆盆地, 前陆逆冲带, 特提斯构造, 天然气地质