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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.
The Greater Himalayan Crystalline complex, also known as the High Himalayan Crystalline Sequence, [14] is composed of high-grade metamorphic rocks aged between Paleoproterozoic and Ordovician. [4] Over the 4.5–8 km thick layer, paragneiss , schist and orthogneiss are observed.
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.
Metamorphic rocks are created by rocks that have been transformed into another kind of rock, usually by some combination of heat, pressure, and chemical alteration. Sedimentary rocks are created by a variety of processes but usually involving deposition, grain by grain, layer by layer, in water or, in the case of terrestrial sediments, on land ...
The Himalayan foreland basin has been divided on the basis of modern drainage divides, [2] and subsurface topography. [7] [8] Subdivisions based on drainage divides are most commonly used, with the Indus Basin reflecting the drainage area of the Indus River, and the Ganga Basin representing the drainage area of the Ganges River.
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 ...