藏北羌塘盆地早侏罗世中侏罗世早期沉积构造特征  

The Sedimentary and Tectonic Characteristics of Qiangtang Basin in the Early Jurassic in Northern Xizang(Tibet)

作　　者：王剑[1] 谭富文[1] 王小龙[1] 杜佰伟[1] 陈明[1] 

机构地区：[1]成都地质矿产研究所,成都610082

出　　处：《沉积学报》2004年第2期198-205,共8页Acta Sedimentologica Sinica

基　　金：国土资源部国际合作与科技司十五重大基础研究项目 (编号 :2 0 0 1 0 2 0 8)资助

摘　　要：侏罗纪早期是研究羌塘盆地形成过程、判别盆地性质的重要时期。通过开展早侏罗世 中侏罗世早期的沉积相、古流向、沉积厚度统计等分析 ,恢复了该时期羌塘盆地的古地理面貌 ,提出了侏罗纪早期羌塘盆地并非前陆盆地 ,而是伸展构造背景下形成的裂陷型盆地。该时期盆地以中央隆起带为界 ,南部为陆缘开阔海盆地 ,形成滨岸 浅海陆棚相碎屑岩沉积 ;北部为陆缘近海湖盆 ,成盆初期 (托尔期 )发生强烈的裂陷活动 ,形成一套火山碎屑岩沉积体系 ,可识别出三个北西向分布的裂陷槽 ,巴柔期快速下沉 ,沉积一套厚达 2 0 0 0m以上的冲积扇 湖泊三角洲 湖盆相碎屑岩夹少量灰岩和石膏沉积 ,沉降中心位于湖盆南部 ,表现出明显的继承性 ,随后逐步向北东迁移 ,海水自中央隆起带中段频繁向湖盆浸漫。巴通期中央隆起带进一步下沉 ,南、北羌塘连成一个统一的拗陷盆地 ,从此沉积作用进入稳定发展阶段 ,形成稳定的碳酸盐岩台地沉积体系。The Early Jurassic sedimentary phase is very important for studying the genetic process and type of Qiangtang Mesozoic basin, while it had an evident uneven fall. Based on lots of stratum sections, this paper makes an analysis to the lithofacies-paleogeographical features, paleocurrent directions, and thickness of the deposits during the period, and suggests that the basin is not foreland basin but fault-depression basin formed in extensional background. During this period, the basin can be divided to three parts,including northern depression, southern depression and central rise belt. The southern depression is continental margin nearshore open basin with littoral-shelf clastic deposit. The northern depression is continental margin nearshore lake basin with volcanic deposit in Toarcian; and pluvial fan and lacustrine clastic deposit bring some carbonates and gypsum in Bajocian, in which three fault-depression troughs can be identified, and the depression center migrated from southwest to northeast. The marine invaded over the middle part of the central rise belt to the lake basin frequently. In Bathonian, the northern and southern depression connects to a uniform basin with the falling of the central rise belt, and came to a stable evolution phase with carbonate deposit.

关 键 词：沉积盆地 油气资源 特提斯 侏罗纪 西藏 沉积构造 

分 类 号：P512.2[天文地球—地质学] P534.52