古地理学报2024，Vol.26Issue(4)：763-778,16.DOI:10.7605/gdlxb.2024.04.059
塔里木盆地阿瓦提凹陷三叠系层序特征与沉积古地理演化
Sequence characteristics and sedimentary palaeogeography evolution of the Triassic in Awati sag,Tarim Basin
摘要
Abstract
In order to clarify the sedimentary-palaeogeography characteristics and sequence frame-work of the Triassic in Awati sag,Tarim Basin,based on the research ideas of terrigenous sequence stra-tigraphy and lake-basin sedimentology,and using basic data consisting of drilling core and seismic data,this paper puts forward new understanding on sequence division,sediment provenance,and sedimentary-palaeogeography distribution and evolution.In this study,the Ohobluk Formation and Karamay Formation of the Triassic in Awati sag are divided into seven third-order sequences,among which the Lower Triassic Ohobluk Formation is divided into five(SQ1-SQ5)and the Middle Triassic Karamay Formation is divid-ed into two sequences(SQ6-SQ7).Each sequence is composed of the lowstand system tract(LST),transgressive system tract(TST),and highstand system tract(HST).It is suggested that the Triassic in Awati sag is characterized by fan deltas,braided river deltas,and shore-shallow lacustrine facies con-trolled by multiple sources.There are four major sources around the sag and the sediment supply is mainly from the southwestern Bachu Uplift and the western Keping Fault Uplift,then from the northern Tabei Up-lift and the southeastern Tazhong Uplift.The braided river delta plain subfacies are mainly distributed at the southern and southwestern edge of the sag,mainly composed of coarse grained sandstone and sandy gravel sandbodies of braided distributary channel microfacies.The center of the lake basin is located in the eastern part of the sag.Within the sag,there are braided delta front subfacies and lacustrine facies,main-ly composed of underwater braided distributary channels and beach bar sandbodies.During the Triassic,the lake basin experienced stages of early initiation,intermediate growth and peak,and finally filling and extinction.The early stage of the Lower Triassic(SQ1-SQ2 period),corresponding to the development of the lower part of the Ohobluk Formation,is the initiation stage of the Awati lake basin in the Triassic.Sediments mainly came from the Bachu Uplift in the south and the Keping Fault Uplift in the west.The sedimentary facies were distributed in an asymmetric belt from south to north,with the development of braided delta plain and front subfacies and shore-shallow lacustrine subfacies.Moreover,during that stages,the lake basin is shallow in the south and deep in the north,shallow in the west and deep in the east.The middle to late stage of the Lower Triassic(SQ3-SQ5 period),corresponding to the development of the upper member of the Ohobluk Formation,is the growth and peak period of lake basin.With the con-tinuous progradation of sources from the southwest and west towards the basin,fan delta facies were formed.At the same time,the lake basin expanded to the north and northeast,forming a braided delta plain and front subfacies that continuously migrated from south to north,while the northeast is a shore-shallow to semi-deep lacustrine subfacies.The early-middle period of the Middle Triassic(SQ6-SQ7 period),corresponding to the development of the Karamay Formation,is the filling and extinction period of the lake basin.The migration of the subsidence center to the northeast region resulted in the continuous progradation of the sources,causing the lake basin to rapidly shrink and eventually died out.关键词
塔里木盆地/阿瓦提凹陷/三叠系/层序/沉积古地理演化Key words
Tarim Basin/Awati sag/Triassic/sequence/sedimentary palaeogeography evolution分类
天文与地球科学引用本文复制引用
贾进华..塔里木盆地阿瓦提凹陷三叠系层序特征与沉积古地理演化[J].古地理学报,2024,26(4):763-778,16.基金项目
国家科技重大专项(编号:2016ZX05046-001)资助.[Financially supported by the National Science and Technology Major Project of China(No.2016ZX05046-001)] （编号:2016ZX05046-001）
