塔里木盆地上奥陶统沉积及古地理特征

THE SEDIMENTARY AND PALAEOGEOGRAPHIC CHARACTERISTICS OF THE UPPER ORDOVICIAN IN THE TARIM BASIN

王恕一 黄继文 蒋小琼

Wang Shuyi Huang Jiwen Jiang Xiaoqong

中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214151, China

晚奥陶世是塔里木盆地沉积—构造重要的转换时期,在寒武—中奥陶世西浅东深的古地理基础上,叠加了南北向隆坳相间的格局,形成了塔里木盆地中西部的混积陆棚沉积体系和东部的深海槽盆沉积体系。由于构造运动的不均衡,中西部的混积陆棚沉积体系无论在纵向和横向上都有很大变化。纵向上呈现出由早期有较多内源碳酸盐沉积到晚期以大量陆源物为主的变化。早中期发育以恰尔巴克组为代表的碳酸盐缓坡沉积(塔北南部和巴楚唐王城一带)和以良里塔格组为代表的碳酸盐台地沉积,形成了塔中、塔北及巴楚唐王城3个碳酸盐台地;晚期则发育以碎屑岩为主的桑塔木组斜坡—潮坪沉积。横向上,远离周边隆起的深坳地区发育却尔却克组混积外陆棚深水盆地浊积沉积(混积陆棚东部)和混积外陆棚深水盆地静水泥岩沉积(柯坪、沙西、阿瓦提一带)。水体较浅、海底坡度较缓的巴楚断隆地区则为混积内陆棚沉积。东部深海槽盆为超补偿深海浊积沉积,与中西部陆棚之间仍保持着地形陡变的坡折带,与外陆棚沉积比较,其浊积层序更发育,粗碎屑也明显增多。

The Late Ordovician epoch is an important period of sedimentation-structure transform in the Tarim Basin.On the palaeogeographic basis of being shallow in the west and deep in the east in the Cambrian-Middle Ordovician epoch,the north-south directional sedimentary framework of uplift alternating with depression was added,forming the diamictic continental shelf deposit system in the center and west and the deep-sea trough basin deposit system in the east of Tarim Basin.Because the tectogenesis was not harmonious,the vertical diamictic continental shelf deposit system in the center and west of Tarim Basin was different from the transverse one.The vertical variation is that there are many autogenic carbonate sediments in the earlier period and that terricolous sediments are dominant in the later period.In the early and middle periods,carbonate mild slope deposit of Qiaerbake Formation and carbonate platform deposit of Lianglitage Formation developed,forming three carbonate platforms in the center and north of Tarim Basin and in Bachu-Tangwangcheng area.In the later period,the Sangtamu Formation slope-tidal flat deposit with detrital rock being dominant developed.Transversely,in the deep depression areas away from the surrounding uplifts,the Querqueke Formation turbidite deposit with diamictic outer continental shelf deep basin facies developed in the east of the diamictic continental shelf and the static water mudstone deposit with diamictic outer continental shelf deep basin facies developed in Keping,Shaxi and Awati areas.In Bachu upheaval area with shallow water body and gentle sea-bottom slope gradient,the diamictic inner continental shelf deposit developed.The supercompensated deep-sea turbidite deposit developed in the eastern deep-sea trough basin.There still exists a slope-break zone with topography greatly varing between the central and western continental shelfs.Comparing with the outer continental shelf deposit,its turbidite sequence further developed and the coarse clastics obviously increased.

https://doi.org/10.11781/sysydz200603236