Collaborative Research: Is the Holocene Slip Rate along the Altyn Tagh Fault 10 mm/y, 30 mm/y, or Both? Infilling a 2-6 ka Data Gap Using 14C, OSL, and Stream Reconstructions

阿尔金断裂活动性强，沿青藏高原西北缘伸展沿着1200多km，是印支-亚洲碰撞带的一级构造。 测量阿尔金断裂带沿着全新世的滑动速率对于加深对主要陆内断裂系统力学行为的理解和区分亚洲地壳和岩石圈相互冲突的流变学模型是必不可少的。 以前的工作已经产生了两个矛盾的滑动速率的中央部分的断层：GPS和古地震学研究给出的速率约为10毫米/年之间的0.01和2-3千年前，而地貌重建产生的速率约为30毫米/年之间的6和113千年前。 在2000年到6000年之间的滑动率数据中有一个重要的时间差距，可以解释为：（1）滑动率在几千年内变化了三倍;（2）恒定和缓慢（约10毫米/年）的滑动率在时间上;或（3）恒定和快速（约30毫米/年）的滑动率在时间上。这项为期三年的沿阿尔金断裂带中心沿着的古地震和滑动速率综合研究将区分这三种假设的滑动历史，以确定两到六千年的间隔。古地震学研究确定了最近地表破裂的大小、年龄、偏移和震级。通过在六个新地点重建位移的河流阶地来确定滑动速率。 正在使用放射性碳、光激发发光和宇宙成因放射性核素方法对移位的河流阶地进行测量和年代测定。阿尔金断层沿着印支-亚洲碰撞中最大的活动走滑断层，它在欧亚大陆变形行为的长期争论中起着核心作用。 这场争论的核心是关于断层在过去10,000年中移动速度的争论。本次调查的结果将（1）解决有争议的滑动速率，并允许扩散和局部大陆变形模型之间的区别;（2）提供观测约束的模型，陆内断层动力学;（3）提高认识的地震风险，不断增长的人口中心附近的阿尔金山断层。

The active, left-slip Altyn Tagh Fault extends for over 1200 km along the northwestern margin of the Tibetan Plateau, making it a first-order structure within the Indo-Asian collision. Measuring the Holocene slip rate along the Altyn Tagh Fault is essential for both advancing understanding of the mechanical behavior of major intracontinental fault systems and discriminating between conflicting rheological models of the Asian crust and lithosphere. Previous work has produced two contradictory slip rates for the central portion of the fault: GPS and paleoseismological studies give rates of about 10mm/y between 0.01 and 2-3 thousand years ago whereas geomorphic reconstructions yield rates of approximately 30 mm/yr between 6 and 113 thousand years ago. There is an important temporal gap in slip-rate data between 2 and 6 thousand years ago that may be explained by: (1) slip rate variations by a factor of three over a few thousand years; (2) constant and slow (about 10 mm/yr) slip rate in time; or (3) constant and fast (about 30mm/yr) slip rate in time. This three-year, integrated paleoseismic and slip-rate study along the central Altyn Tagh fault will distinguish between these three hypothesized slip histories for the 2 to 6 thousand year gap. Paleoseismological studies characterize the size, age, offset and magnitude of the most-recent surface-breaking ruptures. Slip rates are determined by reconstructing displaced fluvial terrace risers at six new sites. Displaced fluvial terraces are being measured and dated using radiocarbon, optically stimulated luminescence, and cosmongenic radionuclide methods. Establishing the Holocene slip history along the Altyn Tagh Fault is important for determining if Asia is best viewed as a collage of microplates or a thin viscous sheet.The Altyn Tagh Fault, the largest active strike-slip fault within the Indo-Asian collision, plays a central role in a long-standing debate over the deformational behavior of the Eurasian continent and, by implication, continents in general. At the heart of this debate lies a dispute over the rate at which the fault moved during the last 10,000 years. The results from this investigation will (1) resolve the disputed slip rate and allow distinction between the diffuse and localized continental deformation models; (2) provide observational constraints for models of intracontinental fault dynamics; and (3) improve understanding of the seismic risk to growing population centers near the Altyn Tagh Fault.