鄂尔多斯盆地燕山运动及其与油气关系

鄂尔多斯盆地是中国中西部重要的含油气盆地之一。燕山期是盆地油气运移和聚集的主要时期。通过晚中生代及其周缘地区沉积格局、构造变形、晚侏罗世—早白垩世的岩浆及热事件的分析 ,认为晚侏罗世以前盆地主要受特提斯构造域的控制 ,古太平洋板块对盆地格局的影响在晚侏罗世晚期以后才有所表现。深部地幔蠕散是盆地古地温场变化的主要原因。它不但导致了盆地地温梯度的急剧升高 ,而且还对后期盆地周缘的地壳浅层次构造变形有一定的影响 ,也是造成晚中生代山西地区与鄂尔多斯盆地差异的重要因素 ,还对油气的运移和聚集起着控制作用。综合燕山期盆地古应力场、古地温场及构造变形特点 ,可以认为燕山期构造运动对鄂尔多斯盆地的油气分布至关重要

YANSHANIAN MOVEMENT IN ORDOS BASIN AND ITS RELATIONSHIP WITH DISTRIBUTION OF OIL AND GAS

Ordos basin is one of the important oil and gas bearing basins in the mid-western part of China. Yanshanian period is the main stage for migration and accumulation of oil and gas in this basin. Based on the analyses of the late Mesozoic sedimentary framework, structural deformation, and of late Jurassic-early Cretaceous magmatic and thermal events in the basin and its adjacent regions, it is suggested that the basin prior to the late Jurassic was mainly controlled by Tethys tectonic domain, whereas influence of Paleo-Pacific plate on the Ordos basin seems to appear until late Jurassic. The possible mechanism of change in paleo-thermal field in the basin was caused by deep mantle dispersion which not only led to drastic raising of the geothermal gradient in the basin, but influenced on late shallow level structural deformation in surrounding regions of the basin. In addition, the mantle dispersion was a dominant factor controlling the migration and accumulation of oil and gas in the basin, and alse an important element for the difference in late Mesozoic between Shanxi region and Ordos basin. In general, the characteristics of paleo-stress field , paleo-geothermal and structural deformation in Yanshan period reflect that the Yanshan movement was playing the most important role for distribution of oil and gas in the basin.