准噶尔盆地西北缘检188井区下侏罗统八道湾组沉积特征及主控因素分析

Sedimentary facies and controlling factors of the Lower Jurassic Badaowan Formation in the Junggar Basin

通过对准噶尔盆地西北缘野外露头剖面和检188井区160多口井的岩石学特征、颜色、结构、沉积构造和古生物沉积相标志的研究,结合测井曲线响应特征,认为该区下侏罗统八道湾组属于湿润型辫状河沉积,发育河道和洪泛平原两个亚相。河道亚相又分为主水道、支水道和心滩3个微相,洪泛平原分为河漫滩、河漫沼泽和溢岸3个微相。测井曲线主要有箱形、钟形、漏斗形、指形和微齿形5种类型。在微相分析基础上编制了八道湾组12个小层的沉积微相平面图,建立了沉积相模式,指出河道呈东南向展布,认为由前陆湖盆边界区的造山运动导致的沉积区基准面变化和潮湿温暖的气候是影响研究区湿润型辫状河形成的主要控制因素。

The integration of lithology,sedimentary textures and structures,palaeontology and well logs shows that the Lower Jurassic Badaowan Formation in the Junggar Basin is assigned to the braided stream deposits under the humid climates,and consist of channel subfacies including the main channel,distributary channel and channel bar microfacies,and flood-plain subfacies including the overbank,backswamp and washover microfacies.These sedimentary microfacies display five types of well logs including box-shaped,belled-shaped,hopper-shaped,finger-shaped and zigzag well logs.The sedimentary microfacies analysis has led to the construction of the plans of 12 sublayers of the Badaowan Formation and sedimentary facies model for the Badaowan Formation.The orogenesis around the foreland lake basin boundary and humid climates are believed to be the main controls on the base-level variations and the formation of the braided stream deposits,respectively.