塔里木盆地奥陶纪岩相古地理特征及礁滩分布

Lithofacies paleogeographical characteristics and reef-shoal distribution during the Ordovician in the Tarim Basin

张丽娟 李勇 周成刚 李猛 韩杰 张博

Zhang Lijuan Li Yong Zhou Chenggang Li Meng Han Jie Zhang Bo

奥陶纪是塔里木盆地及其周缘构造和沉积演化的关键时期。早-中奥陶世海平面开始缓慢上升,塔里木盆地基本继承了晚寒武世的沉积背景;晚奥陶世早期区域构造运动由拉张转为挤压,盆地周边(主要是南边)进一步隆升,台地内的地形分化进一步增大。塔里木盆地在奥陶纪发育了两种类型的台地边缘相,古气候环境适合生物礁体发育。陡坡型台地边缘带相对较窄,礁滩复合体厚度大,平行台缘连续性好,高能相带位于外缘,以塔中Ⅰ号坡折带最为典型;缓坡型台地边缘带相对较宽,礁滩复合体厚度相对较小,由系列的小礁体组成,主要分布在轮南、巴楚凸起边缘、和田河地区。台地边缘礁滩体和台内滩以及岩溶不整合是油气勘探的主攻领域。

The Ordovician is the key period of tectonic movement and depositional evolution in the Tarim basin and its peripheral area.From the Early to Middle Ordovician,the sea level begun to rise slowly and the Tarim basin basically inherited the Late Cambrian sedimentary settings.In the early Late Ordovician,the regional tectonic movement converted from extension to compression,the peripheral area of the basin(mainly to its south) kept uplifting,and the differentiation of topography was enhanced in the platform.In Ordovician,Tarim basin developed two types of platform marginal facies and the paleoclimatic conditions were favorable for reef development.The marginal facies on the steep slop of platform was relatively narrow,the reef-bank complex was large in thickness and good in continuity in direction parallel with the platform margin and the high energy facies belt was located on the outer margin,with Tazhong I slope break zone as a typical example.In contrast,the marginal facies on the gentle slope of platform was relatively wide,the reef complex is relatively small in thickness,composed of small reefs and distributed in Lunnan,the edge of Bachu uplift and Hetian area.Platform marginal reefbanks,intraplateform banks and karst unconformities are main targets of exploration.

10.11743/ogg20070605