塔里木盆地玉北地区奥陶系沉积相与沉积演化模式

在塔里木盆地玉北地区奥陶系层序地层格架建立的基础上,通过对岩心、钻井、测井、地震及古生物等相关资料分析,以地震地层学和海相碳酸盐岩沉积模式为指导,对玉北地区奥陶系沉积相进行详细的研究,结果表明研究区奥陶系可划分为台地潮坪、局限台地、开阔台地、台地边缘、陆架内缘斜坡和陆棚等6种沉积相,并明确了研究区奥陶纪各期沉积相平面展布特征,总结了纵向上的沉积演化规律为:早奥陶世早期发育台地潮坪相;早奥陶世晚期随着海平面的持续缓慢上升,过渡为局限台地相;中奥陶世演化为开阔台地相;晚奥陶世早期演变为斜坡相,至晚奥陶世中晚期则发育陆棚相沉积体系。综合考虑古地理沉积环境、沉积相平面组合规律及控制因素,建立了玉北地区奥陶系沉积演化模式。

Depositional Facies and Sedimentary Evolution Model of Ordovician in Yubei area,Tarim Basin

On the basis of the sequence stratigraphic framework, the sedimentation of Ordovician in the Yubei area of Tarim Basin was studied through the analysis of core, drilling, logging, seismic and palaeontological data. The results show that six sedimentary facies are developed during the Ordovician Period in the studied area, including platform tidal flat, restricted platform, open platform, platform margin, continental margin slope, and shelf. The lateral distribution of sedimentary facies of Ordovician Period were characterized respectively. The characteristics of vertical sedimentary evolution were summarized as follows: At the early stage of Early Ordovician the platform tidal flat facies were developed, and at the late stage, the transitional restricted platform were formed by sea-level rise continuously and gradually, then the open platform facies were developed at Middle Ordovician. At the early stage of Late Ordovician, the slope facies were developed, and at the late stage of Late Ordovician, the shelf depositional system was developed. By the comprehensive analysis of the lateral distribution and vertical evolution of Ordovician sedimentary facies, and the palaeogeographic sedimentary environment, and the controlling factors, the sedimentary evolution models of Ordovician in Yubei area were established.