Main Central Thrust

The Main Central Thrust is a major geological fault where the Indian plate has pushed under the Eurasian plate along the Himalaya. The fault slopes down to the north and is exposed on the surface in a NW-SE direction (strike). It is a thrust fault that continues along 2900 km of the Himalaya mountain belt.[1]

The generally accepted definition of the Main Central Thrust is that it is a ductile shear zone along which the High-grade Great Himalayan Crystalline complex was placed above the low-grade to unmetamorphosed Lesser Himalayan Sequence.[2] However, this definition is not perfect because of many difficulties and complications defining the Main Central Thrust.

Many geologists have researched the Main Central Thrust using various different criteria such as lithology,[2][3] metamorphic isograd,[4] geochronology,[5] geochemistry,[6] and strain magnitude.[7][8] None of these are reliable if used independently. Furthermore, there is uncertainty because of the differences along-strike in the active ages of the Main Central Thrust. It was not all formed at the same time.

Figure 1. Simplified geological map of Himalaya.[9] The Main Central Thrust is indicated by solid line and triangles.
  1. ^ Upreti, B. N. "An overview of the stratigraphy and tectonics of the Nepal Himalaya" Journal of Asian Earth Sciences 17.5 (1994): 577–606.
  2. ^ a b Helm, A., and A. Gansser. "Central Himalaya, Geological observations of the Swiss expedition 1936." Memoires de la Societe Helvetique des Sciences Naturelles 73.1,245 (1939).
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  9. ^ Pierre Dèzes 1999, "Tectonic and metamorphic Evolution of the Central Himalayan Domain in Southeast Zanskar (Kashmir, India)". Mémoires de Géologie (Lausanne) No. 32, ISSN 1015-3578