鄂尔多斯盆地两种不同成因古隆起的特征及其在油气勘探中的意义

Two different genetic types of paleouplift in the Ordos basin and its significance in oil and gas exploration

鄂尔多斯盆地位于华北克拉通西部,是中国大型含油气盆地之一。基底结构复杂,具有明显的不均匀性,基底顶面表现为2个大型隆起,北部为伊克昭盟隆起,中南部为中央古隆起。伊盟隆起具有继承性,继承了结晶基底的形态,上石炭统太原组直接覆盖在变质基底之上。中央古隆起则是盆地西缘和南缘在元古宙秦(岭)祁(连)贺(兰)三叉裂谷基础上发育的古元古代被动大陆边缘,并发展成为主动大陆边缘,于中奥陶世—中石炭世秦祁海槽向东、向北方向俯冲碰撞,形成古生代前陆盆地,其前隆部分平面上构成了L形的中央古隆起。

The Ordos basin located in the west part of the North China craton is one of the large petroleum-bearing basins. It has a complex and obviously heterogeneous basement structure with two large uplifts on top of the basement. The northern one is called the Yimeng paleouplift, and the south-central one, the Central paleouplift. The Yimeng paleouplift inherits the shape of the crystalline basement, with the Upper Carboniferous directly covering the metamorphosed basement; whereas the Central paleouplift is the Paleoproterozoic passive continental margin that originated from the western and southern margins of the Ordos basin on the basis of the Proterozoic Qinling-Qilian-Helan triple rifts and developed as an active continental margin. During the Middle Ordovician to Middle Carboniferous, the Qinling-Qilian ocean trough was subducted and collided in east and north directions, thus forming the Paleozoic foreland basin, and its front bulge formed the L-shaped Central paleouplift.