鄂尔多斯盆地西缘奥陶纪克里摩里期—乌拉力克期构造—岩相古地理特征

Tectonic-lithofacies paleogeographic characteristics of Ordovician Kelimoli and Wulalike stages in the western edge of Ordos Basin

为了查明鄂尔多斯盆地奥陶系克里摩里组—乌拉力克组构造—沉积响应特征,为该区有利勘探区带预测与目标优选提供技术支撑,依据地震、测井、钻井岩心、微观薄片及野外剖面等资料,在构造控沉积思想指导下,对鄂尔多斯盆地西缘奥陶纪克里摩里期—乌拉力克期古构造格局及沉积特征进行了系统研究。结果表明:(1)克里摩里期—乌拉力克期古构造格局整体体现出"一陆一隆一坳、过渡带北东向凸—凹相间"的分异特征;(2)克里摩里期—乌拉力克期为镶边台地沉积模式,沉积相类型包括台地边缘、斜坡、深水陆棚和盆地;(3)古构造格局控制沉积相平面展布,台地边缘沿中央古隆起及隆坳过渡带上的北东向凸起分布;斜坡相主要沿隆坳过渡带上的北东向凹陷分布;深水陆棚相和盆地相主要沿西部坳陷分布。

In order to find out the tectonic-sedimentary characteristics of the Ordovician Kelimoli-Wulalike formations in the Ordos Basin,and provide technical support for the prediction and target optimization of favorable exploration zones in this area,the paleotectonic pattern and sedimentary characteristics of the Ordovician Kelimoli-Wulalike stages in the western edge of the Ordos Basin are studied systematically under the guiding ideology of tectonic controlling deposition,based on seismic,well logging,drilling cores,microscopic thin section and outcrops.The results indicate that:(1)The paleotectonic pattern of the Kelimoli-Wulalike stages reflects the characteristics of"one land,one uplift and one depression,and high and sag alternate with each other along the northeast direction of transition zone";(2)The deposition pattern of the Kelimoli-Wulalike stages is rimmed shelf and the types of sedimentary facies include platform edge,slope,deep-water shelf and basin;(3)The paleotectonic pattern controls the plane distribution of sedimentary facies.The platform margins are distributed along the central paleo-uplift and the NE-trending bulge on the uplift transition zone,the slope facies are mainly distributed along the NE-trending sag on the uplift transition zone;the deep-water shelf facies and basin facies are mainly distributed along the western depression.