江汉盆地西缘宜昌地区下白垩统五龙组辫状河沉积特征  

BRAIDED RIVER DEPOSITS OF THE LOWER CRETACEOUS WULONG FORMATION IN THE YICHANG AREA OF WESTERN JIANGHAN BASIN

作　　者：程龙[1] 李志宏[1] 阎春波[1] 张保民[1] 曾雄伟[1] 周鹏[1] 彭中勤[1] 

机构地区：[1]中国地质调查局武汉地质调查中心,湖北武汉430205

出　　处：《地层学杂志》2018年第1期90-99,共10页Journal of Stratigraphy

基　　金：中国地质调查局地质调查项目(编号:DD20160029)资助

摘　　要：以在江汉盆地西缘宜昌张家坳一带等地测制的4个下白垩统五龙组剖面为基础,笔者通过精细划分岩性组合和沉积构造分析等方法,识别出张家坳一带的五龙组一段和二段下部10种典型的岩相类型及岩相组合类型。根据岩相组合类型,进一步识别出6种属于砾质辫状河典型构型单元,分别为辫状河道、心滩、漫滩、废弃河道、决口扇和决口河道沉积构型单元,但是整体上以辫状河道和心滩构型单元为主。五龙组辫状河沉积在张家坳、土城一带为砾质近源辫状河沉积特征,与冲积扇关系密切,发育在河流的上游地段,主要分布于盆地边缘,物源来自西北部的黄陵背斜剥蚀区,而在向家嘴和三溪口一带相变为砂质辫状河沉积。Four new sections of the Lower Cretaceous Wulong Formation in Yichang area, west Jianghan Basin, were measured and studied. Based on lithological and sedimentary analyses, ten typical lithofacies and ten lithofacies assemblages were identified in the first and second members of the Wulong Formation in the Zhangjiaao area. Six typical rudaceous braid river configurations, including braided channel, mid-chan- nel bar, floodplain, abandoned channel, crevasse splay, and crevasse channel, were further analyzed. O- verall, the braided channel and mid-channel bar were the main configurations. The Wulong Formation ru- daceous braided river deposits in the Zhangjiangao-Tucheng area are near-source sediments related to allu- vial fans. The rudaceous deposits were developed in the upper reach of the rivers, which were located near the basin margin. The sedimentary material came from the erosional area in the northern Huanling anti- cline. The facies changed to sandy braided river deposits between the Xiangjiazui and Sanxikou areas.

关 键 词：资源地层 岩相 构型单元 辫状河 五龙组 下白垩统 江汉盆地 湖北 

分 类 号：P534.53[天文地球—古生物学与地层学]