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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 ...
Metasomatism (from the Greek μετά metá "change" and σῶμα sôma "body") is the chemical alteration of a rock by hydrothermal and other fluids. [1] It is traditionally defined as metamorphism which involves a change in the chemical composition, excluding volatile components. [2]
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 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.
Porphyry – Textural form of igneous rock with large grained crystals in a fine matrix; Pumice – Extremely vesicular volcanic rock, typically light-colored; Pyroxenite – Igneous rock - a coarse grained plutonic rock composed of >90% pyroxene; Quartz diorite – Igneous, plutonic rock – A diorite with >5% modal quartz
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 ...
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith ) is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F) and, often, elevated pressure of 100 megapascals (1,000 bar ) or more, causing profound physical or chemical changes.