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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.
Metavolcanic rock is volcanic rock that shows signs of having experienced metamorphism. [1] In other words, the rock was originally produced by a volcano , either as lava or tephra . The rock was then subjected to high pressure, high temperature or both, for example by burial under younger rocks, causing the original volcanic rock to ...
the Lesser Himalayan Sequence, which is mainly composed of low-grade Proterozoic metasediments to unmetamorphosed rocks, fringed by the Main Boundary Thrust and the Main Central Thrust; the Greater Himalayan Crystalline complex, which is mainly composed by high-grade gneiss and migmatite , fringed below by the Main Central Thrust and the South ...
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.
Prominently orogenic belts on the Earth are the circum-Pacific orogenic belt (Pacific Ring of Fire) and Alpine-Himalayan orogenic belt. [5] Since these orogenic belts are young orogenic belts, they form large mountain ranges; crustal activity is active and accompanied by volcanic belts and seismic belts.
Geologically, the Sivalik Hills belong to the Tertiary deposits of the outer Himalayas. [5] They are chiefly composed of sandstone and conglomerate rock formations, which are the solidified detritus of the Himalayas [5] to their north; they are poorly consolidated. The sedimentary rocks comprising the hills are believed to be 16–5.2 million ...
For example, if the protolith is known to be basalt, the rock will be described as a metabasalt. Likewise, a metamorphic rock whose protolith is known to be a conglomerate will be described as a metaconglomerate. For a metamorphic rock to be classified in this manner, the protolith should be identifiable from the characteristics of the ...