藏南定日地区上三叠统-古近系构造沉降分析与沉积盆地特征  

Tectonic subsidence analysis of Late Triassic-Paleogene strata in Tingri area,Tibetan Tethyan Himalaya and evolution of sedimentary basins

作　　者：李娟[1] 胡修棉[1] 

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学与工程学院,南京210093

出　　处：《岩石学报》2013年第11期3843-3851,共9页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(2012CB822001);中国科学院战略性先导科技专项(B类;XDB03010106);国家自然科学基金项目(41172092)联合资助

摘　　要：构造沉降史研究是沉积盆地分析的一项重要内容。本文对藏南定日地区上三叠统-古近系进行了构造沉降史分析。研究表明:特提斯喜马拉雅定日地区晚三叠世-古近纪经历了由被动大陆边缘盆地沉降向周缘前陆盆地沉降的转换过程,根据构造沉降曲线特征,可划分为五个阶段。第I-III阶段即晚三叠世-晚白垩早期为被动大陆边缘沉降阶段,构造沉降曲线总体比较缓,沉降速率整体呈指数衰减,反映被动大陆边缘稳定的构造沉降过程。第IV阶段晚白垩晚期-古新世早期为构造隆升,古新世晚期再次为稳定构造沉降。对于晚白垩晚期-古新世早期的隆升有两种可能的解释,即德干地幔柱上涌引起的隆升或大陆碰撞板块挠曲引起的隆升。第V阶段始新世时期为印度-亚洲大陆碰撞形成的周缘前陆盆地沉降期,构造沉降曲线斜率增大,沉降速率增加,反映了该时期前陆盆地前渊区快速的沉降特征。Tectonic subsidence history is an important part of the sedimentary basin analysis. This paper draws the tectonic subsidence history of Tibetan Tethyan Himalaya during Late Triassic-Paleogene. Our results show that the Tingrl area of Tethyan Himalayan experienced a transitional subsidence from passive continental margin to peripheral foreland basin and can be divided into five phases. Stages I-III from Late Triassic to early Late Cretaceous are the period of passive margin basin with relatively low tectonic subsidence. The subsidence rate decreases exponentially, reflecting the stable tectonic subsidence process of the passive continental margin. Stage IV shows a late Late Cretaceous-Early Paleocene tectonic uplift followed by Late Paleocene stable tectonic subsidence. There are two possible explanations for the late Late Cretaceous-Early Paleocene tectonic uplift： one is mantle upwelling, another is plate flexure caused by the continental collision. Stage V of Eocene stage is the subsidence of peripheral foreland basin with increased subsidence rate.

关 键 词：构造沉降 晚三叠世-古近纪 被动大陆盆地 前陆盆地 定日 藏南 

分 类 号：P542[天文地球—构造地质学]