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In the igneous environment, metasomatism produces skarns, greisen, and may affect hornfels in the contact metamorphic aureole adjacent to an intrusive rock mass. In the metamorphic environment, metasomatism is driven by mass transfer from a volume of metamorphic rock at higher stress and temperature into a zone with lower stress and temperature ...
The rocks range in age from Precambrian to Miocene. The geology is complicated due to folding, faulting, and thrusting and are largely unfossiliferous. Tectonically, the entire Lesser Himalayas consists of two sequences of rocks: allochthonous, and autochthonous-para autochthonous units; with various nappes, klippes and tectonic windows.
In geology, metasedimentary rock is a type of metamorphic rock. Such a rock was first formed through the deposition and solidification of sediment. Then, the rock was buried underneath subsequent rock and was subjected to high pressures and temperatures, causing the rock to recrystallize. The overall composition of a metasedimentary rock can be ...
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.
Plastiglomerate could potentially form a marker horizon of human pollution on the geologic record. [1] [4] [5] [6] and may survive as future fossils. [2] [5] Plastiglomerate may also conceivably form in plastic-polluted regions affected by lava flows or forest fires. [1] [5] [6] They have been found on the surface as well as beneath the sand.
The nappes—large, stacked sheets of rock—found in the Tethys Himalayan mountain range, are primarily composed of sedimentary rocks, such as limestone formed from the accumulation and compression of sediments like sand, mud, and shells deposited in the Neo-Tethys seabed during the Paleogene" (66 Mya–23 Mya). [23]
The Munsiari Group, originally situated at the base of the Lesser Himalayan Sequence, is exposed at the windows. The crystalline rocks exposed are found to have exceptionally young apatite fission track cooling age of less than 3Ma [23] and rapid cooling rate of 40-50 °C/Ma, [8] comparing to other rocks in the region. This indicates that the ...
Satellite image of the Himalayas Spatial arrangement of the Himalayan tectonostratigraphic zones. Modified from N.R. McKenzie et al 2011 [1]. Pre-collisional Himalaya is the arrangement of the Himalayan rock units before mountain-building processes resulted in the collision of Asia and India.