Chronology of relict lake deposits around the Suwalong paleolandslide in the upper Jinsha River, SE Tibetan Plateau: Implications to Holocene tectonic perturbations
Chronology of relict lake deposits around the Suwalong paleolandslide in the upper Jinsha River, SE Tibetan Plateau: Implications to Holocene tectonic perturbations
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DOI：
10.1016/j.geomorph.2014.04.027
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发表时间：
2014-07
期刊：
影响因子：
3.9
通讯作者：
Pengfei Wang;Jian Chen;Fuchu Dai;W. Long;Chong Xu;Jimin Sun;Z. Cui
中科院分区：
文献类型：
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作者：
Pengfei Wang;Jian Chen;Fuchu Dai;W. Long;Chong Xu;Jimin Sun;Z. Cui
苏瓦隆古滑坡周围暴露出的残体沉积物为认识活动带地区前滑坡堰塞湖的形成过程和可能的成因提供了契机。残坝上下游均发现两级古堰塞湖沉积台地。利用14c测年和OSL测年对滑坡及其周围残湖沉积物进行了年代学研究。阻断金沙江的苏瓦龙滑坡的最小年龄约为1355 yr BP，其周围两个湖相沉积台地的最小年龄分别为1.8和1.3 ka BP。在堰塞湖沉积物中发现了地震液化引起的软沉积变形记录，为古地震事件的存在提供了有力证据。据此推断，苏瓦龙滑坡可能是由古地震或古地震与降雨事件共同引发的。苏瓦龙滑坡坝遗址周围的滑坡堰塞湖沉积物年代学表明，金沙江上游八塘—中杂河段的大规模滑坡形成于多个时期，可能是由几次古地震事件（分别发生在1900年、1355年和1115年BP左右）引发的，表明该地区的金沙江断裂可能在全新世晚期以来非常活跃。
The Suwalong paleolandslide is located in the Batang–Zhongza reach of the upper Jinsha River, at the southeast margin of the Tibetan Plateau where tectonic activity is very strong, and has formed a great deal of large paleolandslides or their relicts. The relict deposits that have been exposed around the Suwalong paleolandslide provide an opportunity to understand the formation process and potential origin of a former landslide-dammed lake in the active belt region. Two-level platforms of ancient dammed lake deposits were found on both the upstream and downstream sides of the relict landslide dam. The chronology of the landslide and its surrounding relict lake deposits were studied by using14C dating and OSL dating. The minimum age of the Suwalong landslide blocking the Jinsha River was shown to be about 1355 yr BP, and those of its surrounding two platforms of lacustrine sediments were shown as 1.8 and 1.3 ka BP. The recordings of the soft-sediment deformations induced by seismic liquefaction were found in the dammed lake sediments, thus providing substantial evidence for the existence of the paleoseismic events. We can infer that the Suwalong landslide may have been triggered by a paleoearthquake or combination of paleoearthquake and rainfall events. The chronology of the landslide-dammed lake deposits around the relict Suwalong landslide dam reveals that the large-scale landslides in the Batang–Zhongza reach of the upper Jinsha River were formed during numerous periods, namely the large-scale landslides may have been triggered by several paleoearthquake events (occurring at around 1900, 1355, and 1115 yr BP), indicating that the Jinsha River faults in the area may have been quite active since the late Holocene.