Geology of the Himalayas

Fig 1: The Earth in the Early Permian (290 million years ago) when India was part of Gondwana and bordered to the north by the Cimmerian Superterrane. Paleogeographic reconstruction by Dèzes (1999), based on Stampfli & Borel (2002) and Patriat & Achache (1984).[a]
Fig 2: The Earth at the Permian-Triassic boundary. The opening of the Neotethys separates the Cimmeridian Superterrane from Gondwana. Based on Stampfli & Borel (2002) and Patriat & Achache (1984).([1][2][3])[b]
Fig 3: The earth in the Cretaceous. The Cimmeridian Superterrane has accreted to Mega Laurasia, the oceanic crust of the Neotethys is subducted to the north along the Dras volcanic arc, the Shigatze Ocean opens as a consequence of back-arc spreading, India is separated from Africa and E. Gondwana and the Indian Ocean opens. Paleogeographic reconstructions based by Dèzes (1999), on Stampfli & Borel (2002) and Patriat & Achache (1984).
Fig 4: The northward drift of India from 71 Ma ago to present time. Note the simultaneous counter-clockwise rotation of India. Collision of the Indian continent with Eurasia occurred at about 55 million years ago. Source: www.usgs.org (modified)
Fig 5: Geologic - Tectonic map of the Himalaya, modified after Le Fort & Cronin (1988). Green is the Indus-Yarlung suture zone.
Fig 6: Geological Map of the NW Himalaya; for references, see image description or bibliography. HHCS: High Himalayan Cristalline Sequence; ISZ: Indus Suture Zone; KW: Kishtwar Window; LKRW: Larji-Kulu-Rampur Window; MBT: Main Boundary Thrust; MCT: Main Central Thrust; SF: Sarchu Fault; ZSZ: Zanskar Shear Zone.
Fig 7: Simplified cross-section of the north-western Himalaya showing the main tectonic units and structural elements by Dèzes (1999).
Fig 8: Indus-Yarlung suture zone separates Himalayas from the Transhimalayas. Lhasa Terrane (also called Karakoram-Lhasa Block/Terrane) lies within the Transhimalayas in its east side. Bangong-Nujiang Suture Zone separates Qiangtang Terrane from the Lahsa Terrane

The geology of the Himalayas is a record of the most dramatic and visible creations of the immense mountain range formed by plate tectonic forces and sculpted by weathering and erosion. The Himalayas, which stretch over 2400 km between the Namcha Barwa syntaxis at the eastern end of the mountain range and the Nanga Parbat syntaxis at the western end, are the result of an ongoing orogeny — the collision of the continental crust of two tectonic plates, namely, the Indian Plate thrusting into the Eurasian Plate. The Himalaya-Tibet region supplies fresh water for more than one-fifth of the world population, and accounts for a quarter of the global sedimentary budget. Topographically, the belt has many superlatives: the highest rate of uplift (nearly 10 mm/year at Nanga Parbat), the highest relief (8848 m at Mt. Everest Chomolangma), among the highest erosion rates at 2–12 mm/yr,[4] the source of some of the greatest rivers and the highest concentration of glaciers outside of the polar regions. This last feature earned the Himalaya its name, originating from the Sanskrit for "the abode of the snow".

From south to north the Himalaya (Himalaya orogen) is divided into 4 parallel tectonostratigraphic zones and 5 thrust faults which extend across the length of Himalaya orogen. Each zone, flanked by the thrust faults on its north and south, has stratigraphy (type of rocks and their layering) different from the adjacent zones. From south to north, the zones and the major faults separating them are the Main Frontal Thrust (MFT), Subhimalaya Zone (also called Sivalik), Main Boundary Thrust (MBT), Lesser Himalaya (further subdivided into the "Lesser Himalayan Sedimentary Zone (LHSZ) and the Lesser Himalayan Crystalline Nappes (LHCN)), Main Central thrust (MCT), Higher (or Greater) Himalayan crystallines (HHC), South Tibetan detachment system (STD), Tethys Himalaya (TH), and the Indus‐Tsangpo Suture Zone (ISZ).[5] North of this lies the Transhimalaya in Tibet which is outside the Himalayas. The Himalayas border the Indo-Gangetic Plain to the south, Pamir Mountains to the west in Central Asia, and the Hengduan Mountains to the east on the China–Myanmar border.

From east to west the Himalayas are divided into 3 regions, Eastern Himalaya, Central Himalaya, and Western Himalaya, which collectively house several nations and states.


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