塔里木盆地上奥陶统桑塔木组混合沉积特征及控制因素

摘要

陆源碎屑与碳酸盐混合沉积是一种沉积机理特殊而又有重要意义的沉积现象,在塔里木盆地上奥陶统桑塔木组广泛发育.在前人研究成果的基础上,本文结合区域地质资料、钻(测)井资料、岩芯观察描述、室内样品分析等,对其混合沉积的沉积特征、沉积类型、沉积环境等方面进行了研究.结果表明:研究区微观上表现为陆源碎屑与碳酸盐沉积物组分的混积岩,宏观上则表现为陆源碎屑岩、碳酸盐岩、混积岩相互叠加的混积层系,混积层系主要分为渐变型,突变I型、突变II型、复合I型、复合II型.发育混合沉积的环境主要为混积潮坪、混积台地、混积台地边缘、混积陆棚.在此基础上以沉积学原理为指导建立了塔里木盆地上奥陶统桑塔木组混合沉积模式,并进一步归纳和讨论了研究区混合沉积的控制因素.%Mixed sedimentation of terrigenous clastic and carbonate is a sedimentary phenomena has special sedimentation mechanism and significant. It is developed extensively in the Upper Ordovician Sangtamu Formation of the Tarim basin. This paper studied the mixed sedimentation in this area based on regional geological data, well logging data, observation of wells cores, indoor sample analysis. The results show that the research area is characterized by interactive sediments of terrigenous clastic and carbonate on the microscopic level, called "mixed sedimentary rock". And in the macro performance of the mixed sequence composed of terrigenous clastic rock, carbonate rock and mixed sedimentary rock. The mixed sequence is divided into 5 types of gradient, mutation-Ⅰ, mutation-Ⅱ, compound-Ⅰ, compound-Ⅱ. Mixed sedimentary environments are occurrence of sedimentary facies such as mixed tidal flat, mixed platform,mixed platform margin, mixed shelf. Combination of tectonic setting and guided by the sedimentary principle, this paper proposed a mixed sedimentation model of the Upper Ordovician Sangtamu Formation in Tarim basin. And further summarized and discussed controlling factors of the mixed sedimentation.