摘要:克拉通盆地内古隆起是了解板内变形机制的重要窗口，也是油气、煤、盐、铀等矿产勘查的主要对象，一直是盆地分析的热点领域。本文以鄂尔多斯盆地中央古隆起为例，利用新的高精度反射地震剖面与深探井资料，解剖古隆起的地质结构，刻画构造演化过程，探讨其形成机制。研究表明，鄂尔多斯盆地古生代隆起带发育在华北克拉通地块中西部，自伊盟—杭锦旗、乌审旗—定边，南延至镇原—正宁一带，呈“工”字形，面积达7.5×104 km2以上；伊盟凸起为基底隆起，镇原隆起为多阶段、间隙性发育的剥蚀与沉积型隆起，定边凸起为沉积型隆起。它是基底分异构造格局与周缘板块构造事件共同控制的产物，为在中元古代裂陷基础上早古生代被动大陆边缘背景下发育演化的古隆起；古生代早期，邻接周缘洋盆表现为台缘隆起；石炭纪晚期—二叠纪早期，因差异升降而具陆缘隆起性质；印支晚期—燕山期以来，隐伏于天环坳陷之下埋藏沉没。鄂尔多斯盆地中央隆起带为多机制复合成因，伊盟凸起为基底强烈伸展、长期剥露剥蚀型隆起；镇原凸起为西缘断阶迁移、南缘前缘隆起叠加的复合隆起；定边凸起为断阶迁移、挤压叠加的继承性隆起。鄂尔多斯盆地中央隆起带对盆地内部的构造—沉积分异施加了重要影响，其两翼斜坡带是油气聚集的有利区带。
关键词: 克拉通盆地/
古隆起/
板内变形/
构造演化/
成因机制/
鄂尔多斯盆地
Abstract:The paleo-uplift in the intra-cratonic basin is not only the key window to understand the in-plate deformation mechanism, but also the main exploration target of the mineral deposits such as oil and gas, coal, salt, and uranium etc. It is always the hot topic for basin analysis. Taking the central paleo-uplift in the Ordos basin as an example, the paper is to analyze its geologic structure, characterize the process of tectonic evolution, and discuss the formation mechanism by utilizing the newly acquired high-resolution reflection seismic profiles and deep boreholes. It shows that, the uplift zone in Paleozoic is situated on the western North China Craton, which goes from the Yimeng-Hangjinqi High in the north, the Wushenqi-Dingbian High in the middle, and to Zhenyuan-Zhenning High in the south taking a form of “工”character in Chinese words, with an area more than 7.5×104 km2. The Yimeng High is a basement uplift, while the Zhenyuan High is a multi-stage and continual depositional uplift intervening with erosion, and the Dingbian High is a typical depositional uplift. The central uplift zone is resulted from both of the differentiation in the basement framework and the tectonic events of the peripheral plates, characterized by the paleo-high under the tectonic setting of passive margin in Early Paleozoic on the basis of the Middle Proterozoic rifts. In the earlier Paleozoic, it is the uplift along the platform margin adjacent to the oceanic basins. In the Late Carboniferous to the Early Permian, it has a character of uplift circled the continent due to the differential subsidence. It is buried under the Mesozoic Tianhuan depression since the late Indosinian to the Yanshanian Movements. It has thus a composite origin of different mechanisms, with the Yimeng High a basement uplift of extensive extension, long-period exhumation, and denudation, the Zhenyuan High a composite uplift characterized by the normal fault-step migration along its western margin and the superimposition of fore-bulges along its southern margin, while the Dingbian High a succeeded uplift being the superimposing of the late period compression upon the early period migration of normal fault-steps. It has an important influences in the tectonic-and-depositional differentiation in the basin with its two limbs the much favorable zones for oil and gas accumulation.
Key words:Cratonic basin/
Paleo-uplift/
In-plate deformation/
Tectonic evolution/
Formation mechanism/
Ordos Basin
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