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.

主动的左滑动Altyn Tagh断层沿着藏族高原的西北边缘延伸了1200公里以上，使其成为印度亚洲碰撞中的一阶结构。 沿Altyn Tagh断层测量全新世滑移速率对于促进对主要肠内断层系统的机械行为的理解以及区分亚洲地壳和岩石圈的矛盾的流变模型至关重要。 先前的工作已经为断层的中央部分产生了两个矛盾的滑移率：GPS和古疗法研究的速率约为10mm/y 0.01至2-3千年前，而地貌重建的产量约为6至11.3千年前的30 mm/yr。 在2到6000年前，滑移率数据存在一个重要的时间差距，可以通过以下方式解释：（1）在几千年的时间内，滑动率变化的三倍； （2）时间恒定且缓慢（约10 mm/yr）的滑动速率；或（3）及时恒定且快速（约30mm/yr）的滑动速率。这项为期三年沿着中央Altyn Tagh断层的三年综合古糖和滑移率研究将区分这三个假设的滑移历史，这是2至6千年的差距。古介质学研究表征了最严重的表面破裂的大小，年龄，偏移和幅度。滑动速率是通过重建六个新地点的流离失所河流立管来确定的。 使用放射性碳，光学刺激的发光和宇宙放射性核素方法测量和日期，正在测量和日期。建立沿着阿尔蒂·塔格（Altyn tagh）断层的全新世滑动历史对于确定亚洲是否最好将亚洲视为微板岩或薄粘性床单。 这场辩论的核心是关于在过去10，000年中过错的速度的争议。这项研究的结果将（1）解决有争议的滑移速率，并允许区分分散和局部大陆变形模型； （2）为室内故障动力学模型提供了观察性约束； （3）提高对阿尔蒂·塔格（Altyn Tagh）断层附近人口中心的地震风险的理解。