新疆叶城晚新生代山前盆地演化与青藏高原北缘的隆升——Ⅱ沉积相与沉积盆地演化

Evolution of Neogene Foreland Basin in Yecheng, Xinjiang, and Uplift of Northern Tibetan Plateau——Ⅱ Facies Analysis

叶城盆地属于塔里木盆地的西南坳陷 ,在晚新生代沉积了巨厚的磨拉石建造。盆地的演化具有阶段性 ,反映了西昆仑山不断的隆升。中新世 ,盆地的沉积环境为曲流河和辨状河等河湖相环境 ,到上新世早期变为冲积扇的远端。晚上新世 (～ 3.6 Ma)开始 ,盆地的沉积环境发生了质的变化 ,沉积物以粗颗粒砾岩为主 ,沉积环境为干旱气候条件下的冲 -洪积扇近端。沉积相的变化 ,反映了昆仑山在晚上新世有强烈的隆升。

The Yecheng foreland basin is a part of the southwest sag of the Tarim Basin and contains late Cenozoic molassic deposits with great thickness. The phased evolution of the basin mirrors the uplift of the Kunlun mountains. The sedimentary environment during the Miocene was characterized by low-gradient meandering rivers, and became distal fan during the Early Pliocene. Significant change in the sedimentary environment occurred in the Late Pliocene, when the deposits were dominated by debris flow material. The basin became a proximal alluvial fan under arid climatic regime. Changes in the sedimentary environment indicate the uplift of the northern Tibetan Plateau since the Late Pliocene.