准噶尔盆地东部滴水泉地区侏罗系八道湾组沉积特征与沉积演化模式

Sedimentary Characteristics and Evolution Model of the Jurassic Badaowan Formation in the Dishuiquan Area in Eastern Junggar Basin

在对区域地质、岩心、测井及地震资料分析的基础上,研究了准噶尔盆地东部滴水泉地区侏罗系八道湾组沉积特征、沉积相展布特征及沉积演化模式。结果表明:研究区八道湾组主要发育辫状河、辫状河三角洲和湖泊3种沉积相类型,可进一步细分为辫状河道、泛滥平原、辫状河三角洲平原、辫状河三角洲前缘及滨浅湖5种亚相类型,以及水道、心滩、湿地、分流河道、水下分流河道、支流间湾、河口坝、远砂坝和滨浅湖泥9种微相类型。J1b1段沉积期,由北东方向的克拉美丽山提供物源,分别向南、向西发育大范围砾质辫状河沉积;J1b2段沉积期,湖进开始由南西向北东方向上超,湖泊范围可达研究区内的古剥蚀区,分布了广阔的湖泊相沉积;J1b3段沉积期,构造活动强烈,物源供给充沛,大量碎屑物从克拉美丽山进入滴水泉地区,形成辫状河三角洲沉积。准噶尔盆地侏罗纪沉积环境及背景条件具有'沟梁相间、盆大水浅、河长扇短、源多坡缓'的特点,结合研究区的沉积特征及沉积展布特征,提出研究区为辫状河—湖泊—辫状河三角洲相结合的沉积演化模式。

Based on the analyses of regional geology, core, logging and seismic data, the sedimentary characteristics, distribution features of sedimentary facies and the sedimentary evolution model of Dishuiquan area are examined. The results show that the study area mainly develops three sedimentary facies including braided river, braided river delta and lacustrine, five types of sedimentary subfacies including braided channel, floodplain, braided river delta plain, braided river delta front and shore-shallow lacustrine, and nine types of sedimentary microfacies including channel, channel bar, wetland, distributary channel, underwater distribu- tary channel, tributary bay, mouth bar, distal bar and shore-shallow lacustrine mud. Based on sedimentary characteristics and deposits distribution, an evolutionary model with braided river-lake-braided river delta facies integrated is proposed. In the deposifional period of J1 b2; the source came from Kelameili Mountain in the northeast,and it developed large area of gravel braided rivers to the south and west. In the depositional period of J1b2 ,the lacustrine transgressive onlapped from southwest to northeast,the lakes could reach the ancient denudation area, and it developed large area of lacustrine sediments. In the depositional period of J1b3 ,tectonic activity were intensive and source supply was abundant. Large amounts of elastic sediments came into the Dishuiquan area from Kelameili Mountain and it developed braided river delta. Jurassic strata in Junggar basin are characterized by ＂groove alternating with roof; shallow water in wide basin; wide- spreading river and restricted fan,multi-source and gentle slope＂.