South Tibetan Detachment

There are three primary rock units present in the Himalaya: the Lesser Himalayan Sequence (LHS; mainly low-grade Proterozoic metasediments, yellow in map), the Greater Himalayan Crystalline complex (GHC; largely high-grade paragneisses and migmatite, orange in map), and the Tethyan Himalayan Sequence (THS; dominantly low-grade late Proterozoic to Eocene shelf sediments; blue in map)[1] More information about these rock units can be found by reading about the geology of Nepal.

Tectonics geologists agree that the GHC, between the LHS and the THS, is between these two faults and is somehow being moved towards the surface and being exposed today.

[4] The main problem that the South Tibetan detachment is expected to help resolve is the method of emplacement of the GHC between the LHS and THS within the Himalaya.

The Himalaya offers many opportunities to study all factors that go into mountain building such as continental collisions, erosion, and even climatic changes.

In respect of it being 'the place where the highest regional scale low-angle normal fault of the Earth can be directly observed', the International Union of Geological Sciences (IUGS) included 'The South Tibetan Detachment System in the Rongbuk Valley' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022.

Figure 1: Geology of the Himalaya: Lesser Himalayan Sequence (yellow), Greater Himalayan Crystalline complex (orange), Tethyan Himalayan Sequence (blue)
Figure 2: Wedge extrusion model.
Figure 3: Channel flow model.
Figure 4: Tectonic wedging model.