西藏定结、定日一带上石炭统纳兴组重力流沉积及其地质意义

西藏定结、定日一带上石炭统纳兴组为一套厚度巨大的陆源碎屑沉积,该组中部首次识别出重力流沉积．重力流沉积可划分为3个类型：崩塌沉积、碎屑流沉积和浊流沉积,以碎屑流沉积常见．通过沉积相和基于沉积物组分及地球化学方面的物源分析,判断该区晚石炭世存在小型洼陷盆地,其形成与晚石炭世海西伸展运动有关,纳兴组重力流沉积与下伏滨浅海沉积之间具一伸展不整合。

Gravity Flow Deposit in Naxing Formation of Upper Carboniferous in Dingjie and Dingri, Tibet, and Their Geological Significances

Naxing Formation of Upper Carboniferous in Dingri and Dingjie, Tibet, is a terrigeneous clastic deposit with huge thickness. Gravity flow facies including collapse, debris flow and turbite facies are distinguished firstly in the middle part of the formation. The sedimentary facies and source analysis based on sediment composition and geochemical characteristics reveals that the environment of the area in Late Carboniferous used to be a small fault basin related with the Hercynian extensional movement, and that an extensional unconformity is situated between the gravity flow facies and shore-shelf facies in the lower part of Naxing Formation.