西藏南部晚侏罗世—白垩纪沉积与构造背景探讨  

THE LATE JURASSIC-CRETACEOUS SEDIMENTARY- TECTONIC DEVELOPMENT OF THE SOUTHERN XIZANG

作　　者：傅德荣[1] 刘训[1] 姚培毅[1] 

机构地区：[1]中国地质科学院地质研究所

出　　处：《地球学报》1990年第2期21-40,共20页Acta Geoscientica Sinica

摘　　要：根据岩石组合特征、沉积构造和沉积相序的分析,结合岩石化学测试数据和粒度分析结果,将西藏南部的晚侏罗世一白垩纪地层划分为5个沉积区,从南往北依次为:喜马拉雅陆棚-外陆棚沉积区;拉轨岗日斜坡沉积区;雅鲁藏布深海盆地沉积区;日喀则弧前盆地沉积区;拉萨弧间盆地沉积区。进一步确定了西藏南部沉积与构造演化的时空关系。In this paper, based on the field work in 1988, the authors suggested some ideas about late Jurassic to Cretaceous sedimentary-tectonic development of the southern Xizang as follows.The Upper Jurassic and Lower Cretaceous in southern Xizang could be divided into five tectonic-sedimentary area, they are: 1. north Himalaya area, which was the north continental margin of the Gandwanalandj 2. Larguigan-gri area, corresponding to the continental slope; 3. Yarlung Zangbo area, representing the oceanic basin of the 'Himalaya-Tethys'; 4. Xigaze area, which was the forearc basin in front of the Gangdesi magmatic arc; 5. Lhasa area, dominated by the late Jurassic to Cretaceous intraarc basin.During late Jurassic, with the spreading of 'Himalaya-Tethys and the thinning of the crust in this area, a deep-water oceanic basin was formed. In the both side of the oceanic basin, the different continental margins occurred. In Himalaya area of the south side, a series of stable-type clastic and carbonate sediments accumulated on the continental shelf, in which the carbon-ate-plateform facies and tidal-flat facies were dominant. Northward, in the Larguigangri area there were some deeper water sediments, represented by siliceous rocks, deep-water red mudstone and carbonate rocks, which implied the incompensated sedimentation on the continental slope. Meanwhile, some deep-water deposits, such as radiolaria- bearing abyssal mudstone and siliceous rocks accumulated in Yarlung Zangbo area, associated with a large number of ophiolites and olistostromes, marked the position of a oceanic basin. Above mentioned showed that the sea-water gradually deepened from south to north, and the tectonic-paleogeographical framework was of a transition from the shallow sea of continental shelf through deeper sea of continental slope to the abyssal oceanic basin, all of which indicated the future of a passive continental margin on the south side of 'Himalaya-Tethys' ocean. On the north side, across the Gangdise magmatic arc, some carbonate-plate-form type

关 键 词：西藏南部 沉积区 弧间盆地 沉积构造 地层划分 构造背景 晚侏罗世 结构成熟度 构造演化 弧前盆地 

分 类 号：P5[天文地球—地质学]