Cretaceous-Earliest Tertiary Basin Development, Deformation, and Magmatism in Southern Tibet: Implications for Pre-Indo-Asian Collision Lithospheric Structure

大陆碰撞造山带是如何受到碰撞事件发生前沿辐合边缘运行的构造过程的影响的？青藏高原被普遍认为是碰撞造山带的原型，它是研究这个问题的一个完美的天然实验室，因为它包含了碰撞前、安第斯风格的弧相关构造以及新生代碰撞构造的记录。青藏高原演化的一般模式以地壳厚度和地幔结构的初始条件假设开始，这些条件对模式的结果有很大影响。然而，对这些假设的地质支持很少。本研究通过对藏南拉萨地体广泛暴露的白垩系和最早第三系盆地充填体和火成岩进行地质填图、构造、地层、沉积学和地质年代学研究，为碰撞前的变形史、盆地发育史、古地理史、剥蚀史和岩浆作用史提供新的约束条件。希望将这些新的约束条件与前人的研究结合起来，形成一个统一的构造模型，为印亚碰撞前藏南岩石圈结构提供现实的初始条件。研究结果对中亚地区新生代造山模式以及一般的碰撞造山模式具有广泛的指导意义。

How are continental collisional orogens preconditioned by tectonic processes that operate along convergent margins prior to the collisional events? The Tibetan plateau, which is generally accepted as the archetype of collisional orogens, is a perfect natural laboratory to study this question because it contains a record of pre-collisional, Andean-style arc-related tectonics as well as collisional tectonics during the Cenozoic. General models for Tibetan Plateau evolution begin with assumptions of initial conditions for crustal thickness and mantle structure that strongly influence the results of the models. However, geological support for these assumptions is scarce. This study is integrating geologic mapping and structural, stratigraphic, sedimentologic, and geochronologic studies of widely exposed Cretaceous and earliest Tertiary basin fill and igneous rocks in the Lhasa terrane of southern Tibet to provide new constraints on the pre-collisional history of strain, basin development, paleogeography, denudation, and magmatism. It is hoped that integration of these new constraints with previous studies will lead to a unified tectonic model that provides realistic initial conditions for the lithospheric structure of southern Tibet prior to the Indo-Asian collision. The results should have broad implications for models of Cenozoic orogeny in central Asia, as well as collisional orogenesis in general.