Changes in paleo-erosion rates, and interactions between erosion, deposition and deformation in the Issyk Kul basin, Kyrgyzstan

伊塞克湖(字面意思是“热湖”)是一个位于中亚中心的大湖，目前是内部排干的。吉尔吉斯天山山脉、南至5216米的Terskey Alatau山脉和北至4973米的昆盖山脉和Zaili Alatau山脉之间的构造位置，解释了丰富的可容纳空间，导致了晚新生代约4公里的地层堆积。超过4000m的冰川山脉，一个拥有约670m深湖的深水欠充填盆地，南北山脉之间5 mm/年的大地GPS测量缩短速率，以及过去几Ma期间进入盆地的活动变形，使这里成为研究中亚强烈侵蚀、沉积和构造信号之间关系的理想地点。同时，它位于西风水汽输送路径上，不受季风影响，使伊塞克库尔成为气候研究的重要目标。事实上，2011年在吉尔吉斯斯坦举行的国际地球科学中心讲习班指出，破译伊塞克湖盆地的形成时间和形成机制对于了解伊塞克湖的演变非常重要。这项建议的重点是量化侵蚀速度随时间的变化。我们的目标是：(1)在地层剖面上利用宇宙成因核素和古地磁方法确定沉积年龄和古侵蚀堆积速率。(2)利用年代地层序列的稳定同位素分析重建古降水和植被格局。(3)编制现有的Issyk Kul盆地测井资料，量化盆地的沉降量，作为该地区构造记录的替代。有了这个综合的数据库，我们将能够处理侵蚀速率随时间的变化，湖盆在百万年时间尺度上的演变，并检查导致侵蚀、沉积和盆地内变形迁移的各种力量之间的相互作用。

Issyk Kul (literally 'Hot Lake') is a large, presently internally-drained lake in the heart of Central Asia. The structural position between mountain ranges belonging to the Kyrgyz Tien Shan, the Terskey Alatau (up to 5216 m) on the south and the Kungey and Zaili Alatau (up to 4973 m) on the north, explains the abundant accommodation space which has lead to the accumulation of ca. 4 km of strata during the late Cenozoic. The combination of glaciated ranges exceeding 4000m, a deep, presently underfilled basin hosting an ~670m deep lake, geodetic GPS-derived shortening rates of 5 mm/yr between the northern and southern ranges, and active deformation which has propagated into the basin during the past several Ma make this is an ideal location to study relationships between the strong erosional, depositional and tectonic signals in Central Asia. At the same time its position in the path of Westerly moisture transport, outside the monsoon influence, makes Issyk Kul an important target for climatic research. Indeed, the 2011 ICDP Workshop held in Kyrgyzstan noted that deciphering the timing and mechanism of formation of the Issyk Kul basin is important for understanding the evolution of Lake Issyk. This proposal focuses on quantifying how erosion rates have changed over time. Our goals are as follows: (1) Determine depositional ages and paleo-erosion and sediment accumulation rates using cosmogenic nuclide and paleomagnetic methods on stratigraphic sections. (2) Reconstruct paleo-precipitation and -vegetation patterns using stable isotopic analyses from dated stratigraphic sequences. (3) Compile existing well logs from the Issyk Kul basin to quantify basin subsidence as a proxy for the tectonic record of the region. With this combined database, we will be able to address changes in erosion rates over time, the evolution of the lake basin over the million year time scale, and examine interactions between the forces responsible for erosion, deposition, and the migration of deformation within the basin.