Has late Cenozoic climate change lead to enhanced erosion in the Kyrgyz and Chinese Tien Shan?

本研究的一个基本问题和主要目标是破译气候和构造在山带演化中的相互作用，特别是晚新生代气候变化是否导致了侵蚀的加剧。我们建议在吉尔吉斯和中国天山地区使用热年代学来检验这一假设。高温法（磷灰石裂变径迹，锆石U-Th/He）将用于确定几个范围的开始和扩展；然后将使用低温法（磷灰石上的U-Th/He）来测试这些地区在过去5 Ma中是否经历了一次强化的挖掘事件。构造地质学和制图将有助于确定挖掘的规模和机制。这将对晚新生代造山带的发育提供一个全面的认识。确定这样一个年轻的构造运动脉冲在空间和时间上是同步的还是不同步的，并将这一记录与以前的历史进行比较，将有助于区分影响变形和隆起的构造和气候驱动因素。该项目的第二个目标是描述天山的新生代构造生长特征，天山是一个由基底隆起组成的破碎前陆，分别类似于北美和南美的Laramide和sierra Pampeanas形态构造省。目前，地震活动性和缩短性分布于整个造山带宽度；然而，缩短开始于山带南缘，并向北迁移。

A fundamental question and the primary goal of this study is deciphering the interplay of climate and tectonics in the evolution of mountain belts, in particular, whether late Cenozoic climate change has led to enhanced erosion. We propose to test this hypothesis in the Kyrgyz and Chinese Tien Shan using thermochronology. Higher temperature methods (apatite fission track, U-Th/He on zircon) will be used to establish the onset and propagation of exhumation of several ranges; lower temperature methods (U-Th/He on apatite) will then be used to test if these regions experienced an enhanced episode of exhumation in the last 5 Ma. Structural geology and mapping will aid in determining the magnitude and mechanisms of exhumation. This will provide a thorough understanding of the late Cenozoic development of the orogen. Determining whether such a young pulse of tectonism is spatially and temporally synchronous or asynchronous and comparing this record with the previous history will allow the differentiation between tectonic and climatic driving factors that influence deformation and uplift. The second goal of this project is to characterize the Cenozoic tectonic growth of the Tien Shan, a broken foreland comprised of basement uplifts akin to the North and South American Laramide and Sierras Pampeanas morphostructural provinces, respectively. At present, seismicity and shortening are distributed throughout the width of the orogen; however, shortening commenced on the southern margin of the mountain belt and migrated northwards.