Tetang Fm
Type Locality and Naming
Thakkhola-Mustang graben fill succession. This formation is well exposed in the vicinity of the village of Tetang and in the Dhinkyo Khola.
Lithology and Thickness
Basal conglomerate (ca. 65 m). Followed by fluvial conglomerates and sandstones, with some intercalated lacustrine limestone, calcareous silt, and siltstone. In it, some thin beds of lignite are also present (Yoshida et al. 1984). The conglomerate contains rounded to subrounded pebbles and cobbles of quartzite, limestone, phyllite, shale, sandstone, and granite. The Tetang Formation is more than 200 m thick
Relationships and Distribution
Lower contact
Major unconformity onto mid-Cretaceous uplifted Muding Fm.
Upper contact
Unconformity (5 to 10 degrees), then Thakkhola Fm.
Regional extent
Southeast part of Thakkhola-Mustang graben fill succession. This Cenozoic east–west extensional phase of Tibet has created many small and some large grabens dated about 14 or 8 Ma (Coleman and Hodges 1995; Harrison et al. 1995; Blisniuk et al. 2001). Some of the important ones are the Thakkhola–Mustang Graben, Gyirong Graben, and Yadong Graben. The Thakkhola–Mustang Graben is about 90 km long and 20–30 km wide.
GeoJSON
Fossils
Plant fossils
Age
Depositional setting
The sediments in the Thakkhola–Mustang graben were deposited in alluvial fan, braided river, glacio-fluvial, and lacustrine environments. The paleocurrent directions measured on imbricated pebbles from all formations of the basin show a generally southwards flow, whereas limestone microfacies analysis indicates a flat and shallow lacustrine environment of carbonate deposition (Adhikari 2009).
Additional Information