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羌塘盆地东部冬曲地区上三叠统巴贡组 沉积环境分析

作    者:占王忠1,2, 彭清华1,2, 陈文彬1,2
单    位:1 中国地质调查局成都地质调查中心; 2 自然资源部沉积盆地与油气资源重点实验室
基金项目:受中国地质调查局项目“羌塘盆地金星湖-隆鄂尼油气资源战略调查”(编号:DD20160159)等联合资
摘    要:
塘盆地东部冬曲地区上三叠统巴贡组主要发育暗色细粒碎屑岩沉积。冬曲野外露头剖面巴贡组碎屑岩的岩性特征、沉积构造、概率累积曲线、粒度参数和C-M图等的分析结果表明:冬曲地区巴贡组砂岩总体较细,分选较差,概率累积曲线主要为“一段式”,悬浮总体含量较高,跳跃总体和滚动总体较少;在C-M图上表现为与C=M基线平行的直线段;沉积构造发育深海—半深海复理石标志性的Paleodictyon古网迹遗迹化石。综合研究认为冬曲地区巴贡组为一套典型的远源滑塌浊积岩沉积。结合邻区巴贡组沉积特征,推测羌塘盆地晚三叠世具有多岛海的古地理格局。
关键词:羌塘盆地;晚三叠世;粒度分析;沉积环境;多岛海

Analysis of depositional environment of the Upper Triassic Bagong Formation in Dongqu area of the eastern Qiangtang Basin

Author's Name: ZHAN Wangzhong,PENG Qinghua,CHEN Wenbin
Institution: Chengdu Geological Survey Center, China Geological Survey
Abstract:
The Upper Triassic Bagong Formation in Dongqu area of the eastern Qiangtang Basin is mainly composed of dark fine clastic rock. The lithologic characters, sedimentary structures, probability cumulative grain size curves, grain-size parameters and C-M pattern of the sandstones of Bagong Formation in Dongqu outcrop profile all show as follows: the sandstones is generally fine and poorly sorted, the probability cumulative curve of the sandstones mostly represents one-stage, with a high percentage of the suspension and low percentage of the traction and saltation. In the C-M diagram, a line segment parallel to the C=M baseline is represented. The sedimentary structure of Paleodictyon trace fossils ,which is flysch marks of deep sea—moderate sea, developed in Bagong Formation. Based on the comprehensive analysis, it is concluded that the Bagong Formation is a typical set of far-source fluxoturbidite in Dongqu area. Combined with the depositional characteristics of Bagong Formation in adjacent area, it is inferred that a palaeogeographic pattern of archipelago in Late Triassic developed in Qiangtang Basin.
Keywords: grain size analysis; sedimentary environment; archipelago; Late Triassic; Qiangtang Basin
投稿时间:2017-11-29  
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