塔里木盆地早古生代构造古地理演化与烃源岩

塔里木陆块为一具前寒武系基底的克拉通盆地,早震旦世—寒武纪陆块内和边缘发生裂解,至中奥陶世转为被动大陆边缘,组建塔北和塔中两个遥相对应的碳酸盐台地和边缘斜坡,其间的阿瓦提—满加尔地区为克拉通内浅海—深水盆。满参1井以东至满加尔为欠补偿的深海槽盆,早期沉积了富生物营养链的烃源岩,晚奥陶世克拉通转为前陆碎屑岩沉积,满加尔坳陷反转为浊流盆地。碎屑岩由东向西、由南东向北西迁移,造成向塔北和塔中海侵上超,结束碳酸盐台地演化的同时,沉积了局限台地型和台缘斜坡灰泥丘相的烃源岩。奥陶纪时塔里木盆地演化和沉积相的配置,是加里东期盆山转换的重要反响,形成多个沉积-构造转换面。早加里东运动,造成下早奥陶统与寒武系的假整合;中加里东运动即晚奥陶世始,塔里木转为前陆盆地,塔北和塔中分别为前陆隆起,阿瓦提—满加尔为复合隆间盆地;晚加里东运动(始于早志留世)发生了大规模的海退。

Tectonic paleogeographic evolution and source rocks of the Early Paleozoic in the Tarim Basin

The Tarim block is a eratonic basin with a Precambrian basement. Between the Early Neoproterozoic and the Cambrian. the Tarim block broke up, and in the Middle Ordovician passive continental margins and associated carbonate platforms developed in the northern and southern parts of the block The Awati-Manjiaer intracratonic basin formed between the north-Tarim platform and the mid-Tarirn platform, while an abyssal incomplete compensational trough Manjiaer basin with slow rate of deposition was formed in an area between the Manjiaer basin and east of Mancan well No. 1. From the Cambrian to the Early Ordovician, a .source rock with abundant organic matter formed in the abyssal trough, but in the Late Ordovician, the Tarim craton changed into a foreland structure with deposition of clastic rocks, while turbidites accumulated in the Manjiaer basir. The migration of terrigenous clastic sediments from east to west and southeast to northwest, resulted in sea transgression onto the north-Tarim and mid-Tarim palaeo-uplifts. Excellent hydrocarbon source rocks of limited platform and margin slope mound facies developed in the marginal slopes of the carbonate platforms. The evolution of Tarim basin and the distribution of its sedimentary facies in the Ordovician are an important reflection of Caledonian basin-range transition, and developed several sedimentary-tectonic- transitional surfaces The Early Caledonian movement resulted in a pseudo-conformity between Cambrian and Low- er OrdovieiarL The Middle Caledonian caused the formation of the Tarim foreland basin, the north-Tarim and centralTarim palaeo-uplifts, and the Awati-Manjiaer basin between the two uplifts. As a result, the tectonic framework of Tarim was established. From the Early Silurian large scale of retrogression bad begun accompanying the Late Caledonian movement.