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之前沿聚合边缘运作的构造过程的预处理的？ 青藏高原被普遍认为是碰撞造山带的原型，是研究这个问题的完美天然实验室，因为它包含了碰撞前、安第斯型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型始于对地壳厚度和地幔结构初始条件的假设，这些初始条件强烈影响模型的结果。 然而，这些假设的地质支持很少。 这项研究将西藏南部拉萨地体广泛暴露的白垩纪和最早的第三纪盆地充填物和火成岩的地质测绘和结构、地层、沉积学和年代学研究结合起来，为碰撞前的应变历史、盆地发育、古地理、剥蚀和岩浆作用提供新的约束。 希望将这些新的约束与先前的研究相结合，形成一个统一的构造模型，为印度-亚洲碰撞之前藏南的岩石圈结构提供现实的初始条件。 这些结果应该对中亚新生代造山运动模型以及一般的碰撞造山作用具有广泛的影响。

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.