摘要
三叠纪时期,塔里木盆地进入前陆盆地演化阶段,发育前陆坳陷、前缘隆起及隆后坳陷3个典型的前陆盆地构造单元。为了探讨隆后坳陷区三角洲沉积特征,以桑塔木地区为例,利用岩心、钻井、测井、分析化验及三维地震等资料,采用"点-线-面"相结合的方法系统研究其三叠系克拉玛依组沉积特征。结果表明,研究区发育辫状河三角洲和曲流河三角洲两大沉积体系,并且垂向上具有辫状河三角洲向曲流河三角洲演化的特征。辫状河三角洲平原以分流河道沉积为主,辫状河三角洲前缘以水下分流河道沉积为主,而河口坝与远砂坝发育规模均较小;曲流河三角洲平原发育分流河道、天然堤及沼泽等,曲流河三角洲前缘则以水下分流河道和河口坝沉积为主。克拉玛依组三角洲的演化不仅受控于前陆盆地构造运动所导致的地形坡度的变化,而且气候由干旱—半干旱向湿润的转化也起到一定作用。在对2类三角洲沉积特征及成因分析的基础上,建立隆后坳陷区三角洲的沉积演化模式。
Tarim Basin entered into foreland basin evolution stage during Triassic period,forming three typical tectonic units（foredeep,forebulge,and backbulge）.In order to discuss the sedimentary characteristics of deltas in the backbulge zone,based on the comprehensive analyses of cores,logging,analysis assay as well as 3D seismic data,the sedimentary characteristics of Triassic Karamay Formation in Sangtamu area were analyzed.The results show that two types of deltas were developed in the study area,namely braided river delta and meandering river delta,and it changed from the former to the latter vertically.The underlying braided river delta is mainly consisted of coarse sandstone,with well lateral continuity and large thickness,while the overlying meandering river delta is exact opposite.Both deltas mainly developed plain and front subfacies.The plain subfacies of braided river delta is primarily composed of distributary channel,while the subaqueous distributary channel microfacies composes the main part of front subfacies,with mouth bar and distal bar locally developed.The distributary channel,levee and swamp microfacies can be identified in meandering river delta plain subfacies,and its front subfacies is chiefly consisted of subaqueous distributary channel and mouth bar.The delta pattern transformation in the study area is controlled by topographic slope change caused by tectonic activities of foreland basin.The paleoclimate changed from arid-semiarid to humid also played an important role.Finally,based on the origin analysis of deltas,the evolution models of delta in backbulge zone were built.
出处
《岩性油气藏》
CSCD
北大核心
2016年第3期34-41,共8页
Lithologic Reservoirs
基金
国家重大油气专项"前陆盆地油气成藏规律
关键技术及目标评价"(编号:2011ZX05003)资助
关键词
辫状河三角洲
曲流河三角洲
沉积特征
演化模式
隆后坳陷
桑塔木地区
braided river delta
meandering river delta
sedimentary characteristics
evolution models
backbulge zone
Sangtamu area
