Pleistocene rapid uplift of the Himalayan frontal ranges recorded in the Kathmandu and Siwalik basins

摘要

Core-drilling project carried out in the southern margin of the Kathmandu Basin revealed that muddy debris flow deposits dammed up the Proto-Bagmati river to form the Paleo-Kathmandu Lake during the Jaramillo subchron from 1.07 to 0.97 Ma. Subsequent deposition of the alluvial fanglomerate, derived from the uplifting Mahabharat Range to the south, raised the dam deepening the lake-water. After 1 Ma, in the southern part of the basin, palaeo-current directions changed from southward to northward and deposition of gneissose and granitic detritus are replaced by meta-sediments derived from the Mahabharat Range.