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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.
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 ...
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.
Despite the difficulties in defining the Main Central Thrust, the following definitions of the Main Central Thrust have been made based on various criteria: By lithologic criteria, the Main Central Thrust is defined as the boundary between quartzite and phyllite , from the Lesser Himalayan Sequence; and the orthogneiss biotite -rich schist ...
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 ...
[22] [24] The Greater Himalayas (also known as Himadri) form the highest section of the Himalayas and extend for about 2,300 km (1,400 mi) from northern Pakistan to northern Arunachal Pradesh in India. The sub-range has an average elevation of more than 6,100 m (20,000 ft) and contains many of the world's tallest peaks, including Everest.
Most rocks contain silicate minerals, compounds that include silica tetrahedra in their crystal lattice, and account for about one-third of all known mineral species and about 95% of the earth's crust. [6] The proportion of silica in rocks and minerals is a major factor in determining their names and properties. [7]