Ore mineralization causing slope failure in a high-altitude mountain crest - on the collapse of an 8000 m peak in Nepal

One of the main preparatory causal factors for the gigantic Tsergo, Ri mass movement (Nepal Himalayas)-the pre-historic failure of a mountain crest encompassing today's Yala Peaks I (5520 m), II (5749 m) and III (5820 m)-was a sulfidic mineralized ore structure within a discordant leucogranitic dike just below these peaks. Geologic mapping within the landslide deposit with special consideration of the broken crest area, structural analysis of the ore body and its gangue, ore microscopy, uniaxial compression tests, SEM analyses of the failure planes, and triaxial compression tests support this thesis. Geomorphologically detailed reconstruction based on a terrain model (scale 1:5000) with the exact position of the broken crest and dislocated mass of the landslide confirms the assumption that the former mountain could have been the earth's 15th 8000 m peak in the Nepalese Himalayas. (C) 2002 Elsevier Science Ltd. All rights reserved.