车排子地区新近系沙湾组物源与沉积相分析

在前人研究基础之上,利用地震、测井、录井、岩心、薄片、地球化学等资料,以砂岩厚度、砂岩碎屑成分、沉积期古地貌、砂岩重矿物含量等多方面的证据确定研究区沙湾组的物源方向,并利用岩石学、粒度分析、测井相、地震相等资料或方法研究沙湾组沉积相类型和展布特征,最后结合构造背景、古地貌、层序地层体系域的构成样式尝试对其沉积相模式进行研究。结果表明:车排子地区沙湾组发育西南方向伊林黑比尔根山和西北方向扎伊尔山两个物源体系,且西南方向的物源延伸距离远,波及范围大;沙湾组发育辫状河三角洲、扇三角洲、湖泊3种沉积相类型,南部地区发育大范围展布的退积型辫状河三角洲,北部主要发育扇三角洲,其前端和侧翼发育滨浅湖滩坝砂沉积;辫状河三角洲前缘水下分支河道砂体容易形成上倾尖灭型岩性圈闭,滨浅湖滩坝砂容易形成透镜体岩性圈闭。

Analysis of provenance and sedimentary facies of Neogene Shawan formation in Chepaizi area

Based on the previous studies and by using the data of seismic,logging,cores,slice and geochemical,the source direction of Shawan group of study area was confirmed through various evidence of sandstone thickness,sandstone clastic composition,paleo-geomorphology and sandstone heavy mineral content.The sedimentary facies and Shawan group exhibition characteristics were studied by means of the data and method of petrology,grain size analysis,log facies and seismic facies.The sedimentary facies model was studied by combining with the construction background,paleo-geomorphology and the structure style of sequence stratigraphic system.The results show that the provenance of Shawan area includes two source system directions,which are Elaine black bill root mountain in southwest direction and Zaire mountain in northwest.Moreover,the extension distance of southwest direction of provenance is long and the influence range is wide.The sedimentary facies of Neogene Shawan group include braided delta,fan delta and lakes phase.Large scope of the southern area exhibits the back multiplicative braided delta and the northern area develops fan delta.And the coastal-shallow lake sand sedimentary appears in the front and the sides.The subaqueous distributary channel sand of braided stream delta front is easy to form the type of pointed lithologic trap and the coastal-shallow lake sand develops the lens lithologic trap easily.