Two times lowering of lake water at around 48 and 38 ka, caused by possible earthquakes, recorded in the Paleo-Kathmandu lake, central Nepal Himalaya
Two times lowering of lake water at around 48 and 38 ka, caused by possible earthquakes, recorded in the Paleo-Kathmandu lake, central Nepal Himalaya
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据记录，尼泊尔喜马拉雅山中部古加德满都湖因可能的地震而在 48 和 38ka 左右出现两次湖水下降
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
M. Paudel
中科院分区：
文献类型：
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作者：
H. Sakai;R. Fujii;M. Sugimoto;R. Setoguchi;M. Paudel
通过沉积相、微化石分析和AMS 14C测年，
尼泊尔喜马拉雅山脉中部过去存在的古加德满都湖水位下降事件和排水过程。加德满都盆地南部和中部由湖相Kalimati组向三角洲相Sunakothi组的沉积相变化，以及植硅体Bambusoideae和盘星藻的突然和显著增加，海绵骨针和炭粒的同时减少，支持了48和38 ka前后水位的下降。根据花粉分析，这两次事件都发生在相对温暖湿润的气候条件下，从而支持它们是由构造原因而不是气候变化触发的。第一个事件可能与可能发生的大地震有关，震中在古加德满都湖附近。在靠近加德满都山谷北部的朗塘地区发生的一次大型滑坡产生的假玄武玻璃岩的年代为51 ± 13 ka，可能与这次地震有关。最后，约12ka时，加德满都盆地中部残留湖的水被完全排干。
AbstractSedimentary facies and micro-fossil analyses, and AMS14C dating were performed in order to reveal
the water-level fall events and draining process of the lake (Paleo-Kathmandu Lake) that existed in the past in the Central Nepal Himalaya. The sedimentary facies change from the lacustrine Kalimati Formation to the deltaic Sunakothi Formation in the southern and central Kathmandu basin, and the abrupt and prominent increase of phytoliths Bambusoideae and Pediastrum, and contemporaneous decrease of sponge spicule and charcoal grains around 48 and 38 ka support the lowering of water level at these times. According to the pollen analysis, both events occurred under rather warm and wet climate, thus supporting that they were triggered by tectonic cause and not by climate change. The first event might be linked to a possible occurrence of a large earthquake with an epicenter in the vicinity of the Paleo-Kathmandu Lake. The occurrence of a mega landslide in Langtang area close to the north of the Kathmandu Valley producing pseudotachylite dated at 51 ± 13 ka could be linked to this earthquake. Finally, the water was completely drained out from the remnant lake at the central part of the Kathmandu basin by ca.12 ka.