Rapid Late Quaternary Slip, Repeated Prehistoric Earthquake Rupture, and Widespread Landsliding Associated With the Karakudzhur Thrust, Central Kyrgyz Tien Shan
Rapid Late Quaternary Slip, Repeated Prehistoric Earthquake Rupture, and Widespread Landsliding Associated With the Karakudzhur Thrust, Central Kyrgyz Tien Shan
复制标题
DOI：
10.1029/2018tc005433
复制
发表时间：
2019-10
期刊：
影响因子：
4.2
通讯作者：
G. Campbell;R. Walker;K. Abdrakhmatov;S. Carolin;A. Carr;J. Elliott;J. Jackson;D. Mackenzie;M. Rizza;Á. Rodés
中科院分区：
文献类型：
--
作者：
G. Campbell;R. Walker;K. Abdrakhmatov;S. Carolin;A. Carr;J. Elliott;J. Jackson;D. Mackenzie;M. Rizza;Á. Rodés
野外研究表明，天山西南部的活动断裂沿山前和盆地内部分布在一系列东西向逆断裂上，其总和缩短速率与GPS测量结果一致。相比之下，很少有现场研究来确定天山中部和东部断层的分布和平均滑动速率。本文利用遥感和野外观测研究了吉尔吉斯斯坦天山中段卡拉库珠尔盆地的活动断裂和构造地貌。我们利用放射性碳测年、发光测年和铀系测年，提供了横跨盆地边界的逆断层垂直位移的三个河流阶地的年龄，并利用20°S倾角断层暴露估计了断层滑动速率。我们发现该断裂全新世的平均滑动速率为∼2.4-5.9 mm/年，这表明它容纳了GPS测量的大部分缩短。与天山西南部N-S缩短的分布相对均匀相反，目前明显的缩短可能集中在天山中部北部的几条活动断裂上。喀喇库珠尔断裂的最新地貌表现表明，它在近代史前曾在一次7级Mw≥大地震中破裂。古地震记录表明，约2.4ka以来曾发生过两次显著的地表破裂地震。最近一次地震可能伴随着周围高地大范围的山体滑坡和断层。
Field studies have shown that active faulting in the SW Tien Shan is distributed across a series of E‐W reverse faults along the range fronts and within basin interiors, with summed shortening rates that are consistent with GPS measurements. In contrast, few field studies have been undertaken to determine the distribution, and the average slip rates, of faults in the central and eastern parts of the Tien Shan. In this paper we use remote and field‐based observations to characterize the active faulting and tectonic geomorphology of the Karakudzhur Basin in the central Tien Shan of Kyrgyzstan. We use radiocarbon, luminescence, and uranium series dating to provide ages on three fluvial terraces that are vertically displaced across the basin‐bounding reverse fault and estimate fault slip rates using a 20°S dipping fault exposure. We find that the fault has a slip‐rate of ∼2.4–5.9 mm/year averaged over the Holocene, indicating that it accommodates a major part of the shortening measured by GPS. In contrast to the relatively uniform distribution of N‐S shortening in the SW Tien Shan, significant shortening may instead be concentrated at present on a few active faults in the northern part of the central Tien Shan. The fresh geomorphic expression of the Karakudzhur fault suggests that it has ruptured in recent prehistory in a large‐magnitude Mw ≥ 7 earthquake. From palaeoseismic trenching we show that two significant surface rupturing earthquakes have occurred since ~2.4 ka. The most recent earthquake was potentially accompanied by widespread landsliding and faulting in the surrounding highlands.