Geology of the Himalaya
Encyclopedia
The geology of the Himalaya is a record of the most dramatic and visible creations of modern plate tectonic forces. The Himalayas
, which stretch over 2400 km between the Namche Barwa syntaxis in Tibet
and the Nanga Parbat
syntaxis in Pakistan
, are the result of an ongoing orogeny
— the result of a collision between two continental tectonic plates
. This immense mountain range
was formed by tectonic forces and sculpted by weathering
and erosion
. The Himalaya-Tibet region supplies freshwater for more than one-fifth of the world population
, and accounts for a quarter of the global sedimentary budget
. Topographically, the belt has many superlatives: the highest rate of uplift (nearly 10 mm/year at Nanga Parbat
), the highest relief (8848 m at Mt. Everest Chomolangma), among the highest erosion rates at 2–12 mm/yr, the source of some of the greatest rivers and the highest concentration of glaciers outside of the polar regions. This last feature earned the Himalaya its name, originating from the Sanskrit
for "the abode of the snow".
and the Palaeozoic, the Indian sub-continent, bounded to the north by the Cimmerian Superterranes
, was part of Gondwana
and was separated from Eurasia
by the Paleo-Tethys Ocean
(Fig. 1). During that period, the northern part of India was affected by a late phase of the Pan-African orogeny
which is marked by an unconformity between Ordovician
continental conglomerates and the underlying Cambrian
marine sediments. Numerous granitic
intrusions dated at around 500 Ma are also attributed to this event.
In the Early Carboniferous
, an early stage of rifting developed between the Indian continent and the Cimmerian Superterranes. During the Early Permian
, this rift
developed into the Neotethys ocean (Fig. 2). From that time on, the Cimmerian Superterranes drifted away from Gondwana towards the north. Nowadays, Iran
, Afghanistan
and Tibet
are partly made up of these terranes.
In the Norian
(210 Ma), a major rifting episode split Gondwana in two parts. The Indian continent became part of East Gondwana, together with Australia
and Antarctica. However, the separation of East and West Gondwana, together with the formation of oceanic crust, occurred later, in the Callovian
(160-155 Ma). The Indian plate then broke off from Australia and Antarctica in the Early Cretaceous
(130-125 Ma) with the opening of the "South Indian Ocean" (Fig. 3).
In the Upper Cretaceous (84 Ma), the Indian plate began its very rapid northward drift covering a distance of about 6000 km, with the oceanic-oceanic subduction continuing until the final closure of the oceanic basin and the obduction
of oceanic ophiolite onto India and the beginning of continent-continent tectonic interaction starting at about 65 Ma in the Central Himalaya. The change of the relative speed between the Indian and Asian plates from very fast (18-19.5 cm/yr) to fast (4.5 cm/yr) at about 55 Ma is circumstantial support for collision then. Since then there has been about 2500 km of crustal shortening and rotating of India by 45° counterclockwise in Northwestern Himalaya to 10°-15° counterclockwise in North Central Nepal relative to Asia (Fig. 4).
While most of the oceanic crust
was "simply" subducted below the Tibetan block during the northward motion of India, at least three major mechanisms have been put forward, either separately or jointly, to explain what happened, since collision, to the 2500 km of "missing continental crust
". The first mechanism also calls upon the subduction of the Indian continental crust below Tibet. Second is the extrusion or escape tectonics mechanism which sees the Indian plate as an indenter that squeezed the Indochina
block out of its way. The third proposed mechanism is that a large part (~1000 km or ~800 to ~1200 km) of the 2500 km of crustal shortening was accommodated by thrusting and folding of the sediments of the passive Indian margin together with the deformation of the Tibetan crust.
Even though it is more than reasonable to argue that this huge amount of crustal shortening most probably results from a combination of these three mechanisms, it is nevertheless the last mechanism which created the high topographic relief of the Himalaya.
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
, which stretch over 2400 km between the Namche Barwa syntaxis in Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...
and the Nanga Parbat
Nanga Parbat
Nanga Parbat is the ninth highest mountain on Earth, the second highest mountain in Pakistan and among the eight-thousanders with a summit elevation of 8,126 meters...
syntaxis in Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
, are the result of an ongoing orogeny
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...
— the result of a collision between two continental tectonic plates
Tectonic Plates
Tectonic Plates is a 1992 independent Canadian film directed by Peter Mettler. Mettler also wrote the screenplay based on the play by Robert Lepage. The film stars Marie Gignac, Céline Bonnier and Robert Lepage.-Plot summary:...
. This immense mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
was formed by tectonic forces and sculpted by weathering
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...
and erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
. The Himalaya-Tibet region supplies freshwater for more than one-fifth of the world population
World population
The world population is the total number of living humans on the planet Earth. As of today, it is estimated to be billion by the United States Census Bureau...
, and accounts for a quarter of the global sedimentary budget
Sedimentary budget
Sedimentary budgets are a coastal management tool used to analyse and describe the different sediment inputs and outputs on the coasts, which is used to predict morphological change in any particular coastline over time...
. Topographically, the belt has many superlatives: the highest rate of uplift (nearly 10 mm/year at Nanga Parbat
Nanga Parbat
Nanga Parbat is the ninth highest mountain on Earth, the second highest mountain in Pakistan and among the eight-thousanders with a summit elevation of 8,126 meters...
), the highest relief (8848 m at Mt. Everest Chomolangma), among the highest erosion rates at 2–12 mm/yr, the source of some of the greatest rivers and the highest concentration of glaciers outside of the polar regions. This last feature earned the Himalaya its name, originating from the Sanskrit
Sanskrit
Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...
for "the abode of the snow".
The making of the Himalaya
During Late PrecambrianPrecambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
and the Palaeozoic, the Indian sub-continent, bounded to the north by the Cimmerian Superterranes
Cimmeria (continent)
Cimmeria was an ancient microcontinent that existed about 200 million years ago. It rifted north from Gondwana during the Late Carboniferous and collided against eastern Laurasia during the Late Triassic together with the Chinese continents. The collision created new mountain ranges between...
, was part of Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
and was separated from Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
by the Paleo-Tethys Ocean
Paleo-Tethys Ocean
The Paleo-Tethys Ocean was an ancient Paleozoic ocean. It was located between the paleocontinent Gondwana and the so called Hunic terranes. These are divided into the European Hunic and Asiatic Hunic...
(Fig. 1). During that period, the northern part of India was affected by a late phase of the Pan-African orogeny
Pan-African orogeny
The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago....
which is marked by an unconformity between Ordovician
Ordovician
The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...
continental conglomerates and the underlying Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
marine sediments. Numerous granitic
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
intrusions dated at around 500 Ma are also attributed to this event.
In the Early Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
, an early stage of rifting developed between the Indian continent and the Cimmerian Superterranes. During the Early Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
, this rift
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....
developed into the Neotethys ocean (Fig. 2). From that time on, the Cimmerian Superterranes drifted away from Gondwana towards the north. Nowadays, Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...
, Afghanistan
Afghanistan
Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...
and Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...
are partly made up of these terranes.
In the Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
(210 Ma), a major rifting episode split Gondwana in two parts. The Indian continent became part of East Gondwana, together with Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and Antarctica. However, the separation of East and West Gondwana, together with the formation of oceanic crust, occurred later, in the Callovian
Callovian
In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....
(160-155 Ma). The Indian plate then broke off from Australia and Antarctica in the Early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
(130-125 Ma) with the opening of the "South Indian Ocean" (Fig. 3).
In the Upper Cretaceous (84 Ma), the Indian plate began its very rapid northward drift covering a distance of about 6000 km, with the oceanic-oceanic subduction continuing until the final closure of the oceanic basin and the obduction
Obduction
Obduction is the overthrusting of continental crust by oceanic crust or mantle rocks at a convergent plate boundary. It can occur during an orogeny, or mountain-building episode....
of oceanic ophiolite onto India and the beginning of continent-continent tectonic interaction starting at about 65 Ma in the Central Himalaya. The change of the relative speed between the Indian and Asian plates from very fast (18-19.5 cm/yr) to fast (4.5 cm/yr) at about 55 Ma is circumstantial support for collision then. Since then there has been about 2500 km of crustal shortening and rotating of India by 45° counterclockwise in Northwestern Himalaya to 10°-15° counterclockwise in North Central Nepal relative to Asia (Fig. 4).
While most of the oceanic crust
Oceanic crust
Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium...
was "simply" subducted below the Tibetan block during the northward motion of India, at least three major mechanisms have been put forward, either separately or jointly, to explain what happened, since collision, to the 2500 km of "missing continental crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
". The first mechanism also calls upon the subduction of the Indian continental crust below Tibet. Second is the extrusion or escape tectonics mechanism which sees the Indian plate as an indenter that squeezed the Indochina
Indochina
The Indochinese peninsula, is a region in Southeast Asia. It lies roughly southwest of China, and east of India. The name has its origins in the French, Indochine, as a combination of the names of "China" and "India", and was adopted when French colonizers in Vietnam began expanding their territory...
block out of its way. The third proposed mechanism is that a large part (~1000 km or ~800 to ~1200 km) of the 2500 km of crustal shortening was accommodated by thrusting and folding of the sediments of the passive Indian margin together with the deformation of the Tibetan crust.
Even though it is more than reasonable to argue that this huge amount of crustal shortening most probably results from a combination of these three mechanisms, it is nevertheless the last mechanism which created the high topographic relief of the Himalaya.
Major tectonic subdivisions of the Himalaya
One of the most striking aspects of the Himalayan orogen is the lateral continuity of its major tectonic elements. The Himalaya is classically divided into four tectonic units that can be followed for more than 2400 km along the belt (Fig. 5 and Fig. 7).- The Subhimalaya forms the foothills of the Himalayan Range and is essentially composed of MioceneMioceneThe Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
to PleistocenePleistoceneThe Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
molassicMolasseThe term "molasse" refers to the sandstones, shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains. The molasse is deposited in a foreland basin, especially on top of flysch, for example that left from the rising Alps, or erosion in the Himalaya...
sediments derived from the erosion of the Himalaya. These molasse deposits, known as the Muree and Siwaliks Formations, are internally folded and imbricated. The Subhimalaya is thrust along the Main Frontal Thrust over the QuaternaryQuaternaryThe Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
alluviumAlluviumAlluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...
deposited by the rivers coming from the Himalaya (Ganges, IndusIndus RiverThe Indus River is a major river which flows through Pakistan. It also has courses through China and India.Originating in the Tibetan plateau of western China in the vicinity of Lake Mansarovar in Tibet Autonomous Region, the river runs a course through the Ladakh district of Jammu and Kashmir and...
, Brahmaputra and others), which demonstrates that the Himalaya is still a very active orogen. - The Lesser Himalaya (LH) is mainly formed by Upper ProterozoicProterozoicThe Proterozoic is a geological eon representing a period before the first abundant complex life on Earth. The name Proterozoic comes from the Greek "earlier life"...
to lower CambrianCambrianThe Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
detrital sediments from the passive Indian margin intercalated with some granites and acid volcanics (1840 ±70 Ma). These sediments are thrust over the Subhimalaya along the Main Boundary Thrust (MBT). The Lesser Himalaya often appears in tectonic windows (Kishtwar or Larji-Kulu-Rampur windows) within the High Himalaya Crystalline Sequence. - The Central Himalayan Domain, (CHD) or High Himalaya, forms the backbone of the Himalayan orogen and encompasses the areas with the highest topographic relief. It is commonly separated into four zones.
- The High Himalayan Crystalline Sequence, HHCS (approximately 30 different names exist in the literature to describe this unit; the most frequently found equivalents are Greater Himalayan Sequence, Tibetan Slab and High Himalayan Crystalline) is a 30-km-thick, medium- to high-grade metamorphic sequence of metasedimentary rocks which are intruded in many places by granites of Ordovician (c. 500 Ma) and early Miocene (c. 22 Ma) age. Although most of the metasediments forming the HHCS are of late ProterozoicProterozoicThe Proterozoic is a geological eon representing a period before the first abundant complex life on Earth. The name Proterozoic comes from the Greek "earlier life"...
to early CambrianCambrianThe Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
age, much younger metasediments can also be found in several areas (Mesozoic in the Tandi syncline and Warwan region, Permian in the Tschuldo slice, Ordovician to Carboniferous in the Sarchu Area). It is now generally accepted that the metasediments of the HHCS represent the metamorphicMetamorphismMetamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
equivalents of the sedimentary series forming the base of the overlying Tethys Himalaya. The HHCS forms a major nappeNappeIn geology, a nappe is a large sheetlike body of rock that has been moved more than or 5 km from its original position. Nappes form during continental plate collisions, when folds are sheared so much that they fold back over on themselves and break apart. The resulting structure is a...
which is thrust over the Lesser Himalaya along the Main Central Thrust (MCT). - The Tethys Himalaya (TH) is an approximately 100-km-wide synclinorium formed by strongly folded and imbricated, weakly metamorphosedMetamorphismMetamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
sedimentary series. Several nappes, termed North Himalayan Nappes have also been described within this unit. An almost complete stratigraphic record ranging from the Upper Proterozoic to the Eocene is preserved within the sediments of the TH. Stratigraphic analysis of these sediments yields important indications on the geological history of the northern continental marginContinental marginThe continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Continental margins constitute about 28% of the oceanic area....
of the Indian continent from its Gondwanian evolution to its continental collision with Eurasia. The transition between the generally low-grade sediments of the Tethys Himalaya and the underlying low- to high-grade rocks of the High Himalayan Crystalline Sequence is usually progressive. But in many places along the Himalayan belt, this transition zone is marked by a major structure, the Central Himalayan Detachment System (also known as South Tibetan Detachment System or North Himalayan Normal Fault) which has indicators of both extension and compression (see ongoing geologic studies section below). - The Nyimaling-Tso Morari Metamorphic Dome, NTMD: In the Ladakh region, the Tethys Himalaya synclinorium passes gradually to the north in a large dome of greenschistGreenschistGreenschist is a general field petrologic term applied to metamorphic or altered mafic volcanic rock. The term greenstone is sometimes used to refer to greenschist but can refer to other rock types too. The green is due to abundant green chlorite, actinolite and epidote minerals that dominate the...
to eclogiticEclogiteEclogite is a mafic metamorphic rock. Eclogite is of special interest for at least two reasons. First, it forms at pressures greater than those typical of the crust of the Earth...
metamorphicMetamorphismMetamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
rocks. As with the HHCS, these metamorphic rocks represent the metamorphic equivalent of the sediments forming the base of the Tethys Himalaya. The Precambrian Phe Formation is also here intruded by several Ordovician (c. 480 Ma) granites. - The Lamayuru and Markha Units (LMU) are formed by flyschFlyschFlysch is a sequence of sedimentary rocks that is deposited in a deep marine facies in the foreland basin of a developing orogen. Flysch is typically deposited during an early stage of the orogenesis. When the orogen evolves the foreland basin becomes shallower and molasse is deposited on top of...
s and olistholiths deposited in a turbiditicTurbiditeTurbidite geological formations have their origins in turbidity current deposits, which are deposits from a form of underwater avalanche that are responsible for distributing vast amounts of clastic sediment into the deep ocean.-The ideal turbidite sequence:...
environment, on the northern part of the Indian continental slope and in the adjoining Neotethys basin. The age of these sediments ranges from Late Permian to Eocene.
- The High Himalayan Crystalline Sequence, HHCS (approximately 30 different names exist in the literature to describe this unit; the most frequently found equivalents are Greater Himalayan Sequence, Tibetan Slab and High Himalayan Crystalline) is a 30-km-thick, medium- to high-grade metamorphic sequence of metasedimentary rocks which are intruded in many places by granites of Ordovician (c. 500 Ma) and early Miocene (c. 22 Ma) age. Although most of the metasediments forming the HHCS are of late Proterozoic
- The Indus Suture Zone (ISZ) (or Indus-Yarlung-Tsangpo Suture Zone) defines the zone of collision between the Indian Plate and the Ladakh Batholith (also Transhimalaya or Karakoram-Lhasa Block) to the north. This suture zone is formed by:
-
-
- the Ophiolite MélangeMélangeIn geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically consists of a jumble of large blocks of varied lithologies...
s, which are composed of an intercalation of flysch and ophiolites from the Neotethys oceanic crust - the Dras Volcanics, which are relicts of a Late Cretaceous to Late JurassicJurassicThe Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
volcanic island arc and consist of basaltBasaltBasalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
s, daciteDaciteDacite is an igneous, volcanic rock. It has an aphanitic to porphyritic texture and is intermediate in composition between andesite and rhyolite. The relative proportions of feldspars and quartz in dacite, and in many other volcanic rocks, are illustrated in the QAPF diagram...
s, volcanoclastites, pillow lavaPillow lavaPillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in...
s and minor radiolarianRadiolariteRadiolarite is a siliceous, comparatively hard, fine-grained, chert-like, and homogeneous sedimentary rock that is composed predominantly of the microscopic remains of radiolarians. This term is also used for indurated radiolarian oozes and sometimes as a synonym of radiolarian earth...
chertChertChert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
s - the Indus MolasseMolasseThe term "molasse" refers to the sandstones, shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains. The molasse is deposited in a foreland basin, especially on top of flysch, for example that left from the rising Alps, or erosion in the Himalaya...
, which is a continental clastic sequence (with rare interbeds of marine saltwater sediments) comprising alluvial fanAlluvial fanAn alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...
, braided stream and fluvio-lacustrine sediments derived mainly from the Ladakh batholith but also from the suture zone itself and the Tethyan Himalaya. These molasses are post-collisional and thus Eocene to post-Eocene. - The Indus Suture ZoneIndus-Yarlung suture zoneThe Indus-Yarlung suture zone or the Indus-Yarlung Zangbo suture is a tectonic suture in southern Tibet and across the north margin of the Himalayas which resulted from the collision between the Indian plate and the Eurasian plate starting about 52 Ma. The north side of the suture zone is the...
represents the northern limit of the Himalaya. Further to the North is the so-called Transhimalaya, or more locally LadakhLadakhLadakh is a region of Jammu and Kashmir, the northernmost state of the Republic of India. It lies between the Kunlun mountain range in the north and the main Great Himalayas to the south, inhabited by people of Indo-Aryan and Tibetan descent...
Batholith, which corresponds essentially to an active margin of Andean type. Widespread volcanismVolcanismVolcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....
in this volcanic arcVolcanic arcA volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...
was caused by the melting of the mantleMantle (geology)The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....
at the base of the Tibetan bloc, triggered by the dehydrationDehydrationIn physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
of the subducting Indian oceanic crust.
- the Ophiolite Mélange
-
See also
Localized geology and geomorphology topics for various parts of the Himalaya are discussed on other pages:- ZanskarZanskarZanskar is a subdistrict or tehsil of the Kargil district, which lies in the eastern half of the Indian state of Jammu and Kashmir. The administrative centre is Padum...
is a subdistrict of the Kargil districtKargil DistrictKargil is a district of Ladakh, Kashmir, India. Kargil lies near the Line of Control facing Pakistan-occupied Kashmir's Baltistan to the west, and Kashmir valley to the south. Zanskar is part of Kargil district along with Suru, Wakha and Dras valleys...
, which lies in the eastern half of the IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n state of Jammu and KashmirJammu and KashmirJammu and Kashmir is the northernmost state of India. It is situated mostly in the Himalayan mountains. Jammu and Kashmir shares a border with the states of Himachal Pradesh and Punjab to the south and internationally with the People's Republic of China to the north and east and the...
. - Indus River - the erosion at Nanga ParbatNanga ParbatNanga Parbat is the ninth highest mountain on Earth, the second highest mountain in Pakistan and among the eight-thousanders with a summit elevation of 8,126 meters...
is causing rapid uplifting of lower crustal rocks - Mount Everest
- Sutlej River - similar small scale erosion to the Indus
- Tibetan PlateauTibetan PlateauThe Tibetan Plateau , also known as the Qinghai–Tibetan Plateau is a vast, elevated plateau in Central Asia covering most of the Tibet Autonomous Region and Qinghai, in addition to smaller portions of western Sichuan, southwestern Gansu, and northern Yunnan in Western China and Ladakh in...
to the North (also discussed in Geography of TibetGeography of TibetThe geography of Tibet consists of the high mountains, lakes and rivers lying between Central, East and South Asia. Traditionally, Western sources have regarded Tibet as being in Central Asia, though today's maps show a trend toward considering all of modern China, including Tibet, to be part of...
) - Paleotethys
- HimalayasHimalayasThe Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
main page
External links
- "Geology and Petrographic study of the area from Chiraundi Khola to Thulo Khola, Dhading/Nawakot district, central Nepal". MS Thesis by Gyanendra Gurung
- Granitoids of the Himalayan Collisional Belt. Special Edition of "The Journal of the Virtual Explorer"
- Reconstruction of the evolution of the Alpine-Himalayan orogeny. Special Edition of "The Journal of the Virtual Explorer"
- "Geology of Nepal for Engineer"
- Wadia Institute of Himalayan Geology, Dehradun,India, main page