Provenance analysis of Neogene sediments in the Thakkhola-Mustang Graben (central Nepal)

The Thakkhola-Mustang Graben, which reflects Neogene extensional tectonics in the Tibetan Plateau and Himalaya, lies north of the Dhaulagiri-Annapurna ranges and south of the Yarlung-Tsangpo Suture Zone. The regional geology of the basin is dominated by a basement of Tibetan-Tethys sedimentary rocks of Paleozoic and Mesozoic ages, unconformably overlain by continental debris (more than 850 m) of Neogene to Quaternary age (Fort et al., 1982; Yoshida et al., 1984). Stratigraphically, the graben sediments have been divided into four formations; the Miocene Tetang and Thakkhola formations, disconformably overlain by the Plio-Pleistocene Sammargaon and Marpha formations. In the present study, the sediment provenance and the nature of the source rocks have been investigated.