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

合作研究：阿尔金断裂带全新世滑移率是10毫米/年、30毫米/年还是两者？

• 批准号: 0610040
• 负责人: J Ramon Arrowsmith
• 金额: $ 19.55万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0610040&HistoricalAwards=false
• 关键词: Collaborative; Research; Holocene; Slip; Rate

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.

活跃的左滑阿尔金断裂带沿青藏高原西北缘延伸1200多公里，是印亚碰撞中的一级构造。 测量沿阿尔金断层的全新世滑移率对于增进对主要陆内断层系统力学行为的理解以及区分亚洲地壳和岩石圈相互冲突的流变模型至关重要。 先前的工作对于断层的中心部分产生了两种相互矛盾的滑动速率：GPS和古地震学研究给出了0.01至2-3000年前的约10毫米/年的速率，而地貌重建产生的6至2000年前的约30毫米/年的速率。 11.3万年前。 2 到 6 千年前的滑移率数据存在一个重要的时间间隔，这可以通过以下方式解释：(1) 滑移率在几千年中变化了三倍； (2) 及时保持恒定且缓慢（约10毫米/年）的滑移率； (3) 及时保持恒定且快速（约 30 毫米/年）的滑移率。这项沿阿尔金断裂带中部进行的为期三年的综合古地震和滑移率研究将区分这三种假设的 2 至 6 千年间的滑移历史。古地震学研究描述了最近地表破裂破裂的大小、年龄、偏移量和震级。滑移率是通过在六个新地点重建移位的河流阶地立管来确定的。 正在使用放射性碳、光激发光和宇宙放射性核素方法对流离失所的河流阶地进行测量和年代测定。沿着阿尔金断层建立全新世滑动历史对于确定亚洲是否最好被视为微板块拼贴画或薄粘性片很重要。阿尔金断层是印度-亚洲碰撞中最大的活动走滑断层。在关于欧亚大陆乃至整个大陆变形行为的长期争论中发挥着核心作用。 这场争论的核心在于过去一万年断层移动速度的争论。这项调查的结果将（1）解决有争议的滑动率，并允许区分扩散和局部大陆变形模型； (2)为陆内断层动力学模型提供观测约束； (3) 提高对阿尔金断层附近不断增长的人口中心的地震风险的了解。