唐古拉山地区三叠纪层序地层分析及构造演化

Sequence stratigraphy and tectonic evolution of the Triassic strata in the Tanggula Mountain area,Xizang

三叠纪充填的一套碳酸盐岩—碎屑岩地层,被划分为两个超层序和5个层序单元。超层序Ⅰ以复理石建造为特征,是金沙江缝合带初始碰撞作用的产物,是唐古拉山地区三叠纪前陆盆地早期挠曲沉降构造活动的沉积响应,标志着晚三叠世诺利期前陆盆地业已形成;超层序Ⅱ以磨拉石与酸性火山岩建造为特征,是前陆盆地晚期冲断抬升构造演化的沉积响应,表明晚三叠世瑞替期来自造山带的沉积物开始越过前陆隆起向隆后盆地迁移。

The Triassic carbonate-siliciclastic strata in the Tanggula Mountain area are separated, by three regional tectonic-sequence boundaries （Ta, Td and Tf） and three sequence boundaries （Tb, Tc and Te）, into two supersequences and five sequences. Supersequence 1 dominated by flysch formations as the products formed during the initial collision of the Jinshajiang suture zone and sedimentary responses to the tectonic events of downwarping and settlement in the early stage of the Triassic foreland basin marks the formation of the foreland basin in the Tanggula Mountain area during the Norian （Late Triassic）. Supersequence 2 dominated by molasses and acidic volcanic formations occur as the sedimentary responses to the tectonic events of thrusting and uplifting in the foreland basin during the Triassic, implying that the sediments derived from the orogenic zones bypassed the foreland uplifts and migrated towards the back-uplift basin during the Rhaetian （Late Triassic）.