Thakkhola Fm
Type Locality and Naming
Thakkhola graben fill succession. The Thakkhola Formation covers mainly the central and north parts of the graben.
Lithology and Thickness
Lacustrine silt with coarse clastics. Most of the lower half of the succession is represented by alluvial fan and fluvial conglomerates with subrounded pebbles and cobbles of limestone, quartzite, sandstone, and granite. Beds of lacustrine limestone, calcareous siltstone, and sandstone also occur at various intervals; especially the upper half. The Thakkhola Formation is more than 600 m thick and younger than 8 Ma (Garzione et al. 2000, 2003).
Relationships and Distribution
Lower contact
Unconformity (5 to 10 degrees), with Tetang Fm below.
Upper contact
Overlain by Sammargaon Fm
Regional extent
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
Age
Depositional setting
Alluvial and lacustrine. 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