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The geology of Kyrgyzstan began to form during the Proterozoic. The country has experienced long-running uplift events, forming the Tian Shan mountains and large, sediment filled basins. [1]
The Precambrian tectonic evolution of the region is poorly understood. Geologists infer that the Northern Turkestan domain likely formed along the margin of the Proterozoic Baltica-Siberia continent. The Tarim Block may have belonged to Gondwanaland, based on paleontological evidence. Although paleomagnetic data for the Tien Shan mountains is lacking, some have suggested that the ocean closed to form the Turkestan domain may have been a branch of the proto-Pacific Ocean. The Paleozoic rocks in the Tien Shan mountains are the remnants of accreted island arcs, mainly from the Ordovician onward.
During the Vendian, the Northern Turkestan domain was part of the Kipchak island arc system between the East European and Siberian continent, separated by the Terksey back-arc basin which had originated as a rift basin. The Tien Shan mountains began to form in the Ordovician out of three island arcs amalgamated by the subduction of Terksey oceanic crust beneath the Kungey Arc, Sandalash Arc and subduction of Paleotethys Ocean crust under the Yagnob Arc. The Kyrgyz Block formed in the middle Ordovician with closure of the Terksey Basin and then underwent deformation. Coarse molasse sediments lie unconformably on top of subduction-related granite intrusions and volcanic rocks. North and south of the Terksey Suture, formed during the event, late Ordovician collision-related granites.
Into the Silurian, the Sandalash magmatic arc remained along the southern margin of the Kyrgyz Block. Turkestan oceanic crust was subducated beneath the Sandalash magmatic arc. By the early Devonian, magmatic activity was taking place in the northern Tien Shan mountains, likely as a result of the subducting Turkestan crust. Sedimentation occurred in shallow seas and on the passive margin of the Tarim-Alay Block.
Magmatic activity resumed in the Carboniferous, with spreading in the Turkestan Ocean and renewed subduction under the Kyrgyz Block. By the late Carboniferous, collision between the Tarim-Alay microcontinent and the Kyrgyz Block was underway, emplacing large nappe features with ophiolite deposits on top of the Tarim-Alay basement rocks. Magmatism continued through the Permian in the Tien Shan mountains, accompanied by deformation and the deposition of molasse sediments in different basins. [2]
Structural geologists distinguish a number of tectonic features from the Paleozoic including the Nikolaev's Line, Talas-Fergana Fault, Turkestan Suture and Terskey Suture.
At the start of the Mesozoic, depressions began to develop in the Triassic, accumulating thick, coal-bearing sediments. The East Fergana pull-apart basin aligned along the Talas-Fergana Fault. The western edge of the basin has delta sediments while the center of the basin reflects deep water sediments. Material and fossils continued to accumulate into the Jurassic as the units were folded.
A shallow water basin covered the region in the Cretaceous, leaving behind salt water fauna west of the Talas-Fergana fault. Alluvial deposits mark the edges of the saline lake and Cretaceous deposits accumulated up to 500 meters thick. The lake became a shallow intracontinental sea, lasting into the Cenozoic. Lagoon deposits accumulated through the Eocene, until the sea began to retreat in late Paleogene times. The retreat was brought on with the collision of India with Asia around 50 million years ago. Cretaceous-Eocene sedimentary rocks are up to two kilometers thick in the Fergana Basin. The Oligocene, the entire region had shifted to lagoon and continental deposition.
To the east of the Fergana Range, there are no Cretaceous or Paleocene sediments. Continental sediments accumulated there beginning in the Eocene, formed clay, siltstone and sandstone, interbedded with thinner layers of gypsum, marl, conglomerate and limestone in river valleys formed in the central Tien Shan Mountains in the Oligocene and Miocene. These deposits range widely from several meters thick to several kilometers. They reach their greatest thickness of four kilometers in Fergana, Atbashi and Naryn basins. Tien Shan mountain rocks show no signs of folding from the Cretaceous through the Paleogene and lie with an angular unconformity atop basement rocks.
Tectonic activity rapidly resumed in the late Pliocene, leading to erosion of continental sediments into intermontane basins into the Quaternary. Folding developed into the Quaternary in the Tien Shan mountains as global changes in climate brought on the Pleistocene ice ages. Most ridges in the mountain range are asymmetric anticlines bounded by reverse and thrust faults. Folding and thrusting is often oriented toward major basins like the Fergana, Chur or Tarim basins. [3]
Due to tectonic activity since the Pliocene, Kyrgyzstan has intense seismic activity on a regular basis. There have been more than 11 earthquakes magnitude 6 or greater on the Richter scale since 1865. The most activity centers on the Kyrgyz Ranges, Kungey Ranges and East Fergana region.
Kyrgyzstan is notable for significant deposits of antimony and mercury, such as the Chauvay, Kadamzhai and Khaydarkan deposits. These are examples of quartz-fluorite-antimonite-cinnabar (also known as jasperoid type deposits), while others are quartz-dickite-cinnabar or magnesian-carbonate-cinnabar (or listvenite)_ types. The primary types of deposits are common at the contact between Carboniferous limestone and overlying Silurian shales and Devonian sandstone nappe formations. Listvenite deposits are typically associated with serpentine mélange. Contact metamorphism skarn deposit gold, hydrothermal gold, pegmatite hosted tin, cassiterite-quartz and iron ore in Proterozoic slates are also common together, with smaller amounts of zinc, aluminum, lead, vanadium and uranium.
Oil and gas are found in commercial quantities in the Fergana Basin in Jurassic, Cretaceous, Paleogene and Neogene sedimentary rocks. The oil is low in sulfur and the natural gas is dry with up to 72 percent methane. The South Fergana Basin, the Uzgen Basin, Kavak Basin and Southern Issyk Kul Basin all host coal deposits from the Triassic and Jurassic formed under continental conditions, with 70 percent hard coal. [4]
The Alay or Alai Range is a mountain range that extends from the Tien Shan mountain range in Kyrgyzstan west into Tajikistan. It is part of the Pamir-Alay mountain system. The range runs approximately east to west. Its highest summit is Pik Tandykul, reaching 5544 m. It forms the southern border of the Fergana Valley, and in the south it falls steeply to the Alay Valley. The southern slopes of the range drain into the Kyzylsuu or Vakhsh River, a tributary of the Amu Darya. The streams that drain the northern slopes of the range are tributaries of the Syr Darya, and empty into the Fergana Valley to the north of the range. Pik Skobeleva, 5,051 metres (16,572 ft), is also a well-known summit. European route E007: Tashkent – Kokand – Andijan – Osh – Irkeshtam crosses the range by the Taldyk Pass. The range is also traversed by Pamir highway.
The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediments from the mountain chain spread throughout the present-day Appalachians and midcontinental North America.
The Tian Shan is a mountain range in central Asia that extends through western China, Kazakhstan, and Kyrgyzstan. The Tian Shan is 2,800 kilometres (1,700 mi) long, and up to 7,400 metres (24,300 ft) high. Throughout the Tian Shan there are several intermontane basins separated by high ranges. Plate tectonic theory makes the assumption that deformation is concentrated along plate boundaries. However, active deformation is observed in the Tian Shan, far from plate boundaries. This apparent contradiction of plate tectonic theory makes the Tian Shan a key place to study the dynamics of intracontinental deformation.
The Lhasa terrane is a terrane, or fragment of crustal material, sutured to the Eurasian Plate during the Cretaceous that forms present-day southern Tibet. It takes its name from the city of Lhasa in the Tibet Autonomous Region, China. The northern part may have originated in the East African Orogeny, while the southern part appears to have once been part of Australia. The two parts joined, were later attached to Asia, and then were impacted by the collision of the Indian Plate that formed the Himalayas.
The base of rocks that underlie Borneo, an island in Southeast Asia, was formed by the arc-continent collisions, continent–continent collisions and subduction–accretion due to convergence between the Asian, India–Australia, and Philippine Sea-Pacific plates over the last 400 million years. The active geological processes of Borneo are mild as all of the volcanoes are extinct. The geological forces shaping SE Asia today are from three plate boundaries: the collisional zone in Sulawesi southeast of Borneo, the Java-Sumatra subduction boundary and the India-Eurasia continental collision.
The geology of Myanmar is shaped by dramatic, ongoing tectonic processes controlled by shifting tectonic components as the Indian plate slides northwards and towards Southeast Asia. Myanmar spans across parts of three tectonic plates separated by north-trending faults. To the west, a highly oblique subduction zone separates the offshore Indian plate from the Burma microplate, which underlies most of the country. In the center-east of Myanmar, a right lateral strike slip fault extends from south to north across more than 1,000 km (620 mi). These tectonic zones are responsible for large earthquakes in the region. The India-Eurasia plate collision which initiated in the Eocene provides the last geological pieces of Myanmar, and thus Myanmar preserves a more extensive Cenozoic geological record as compared to records of the Mesozoic and Paleozoic eras. Myanmar is physiographically divided into three regions: the Indo-Burman Range, Myanmar Central Belt and the Shan Plateau; these all display an arcuate shape bulging westwards. The varying regional tectonic settings of Myanmar not only give rise to disparate regional features, but they also foster the formation of petroleum basins and a diverse mix of mineral resources.
The geology of Ukraine is the regional study of rocks, minerals, tectonics, natural resources and groundwater in Ukraine. The oldest rocks in the region are part of the Ukrainian Shield and formed more than 2.5 billion years ago in the Archean eon of the Precambrian. Extensive tectonic evolution and numerous orogeny mountain-building events fractured the crust into numerous block, horsts, grabens and depressions. Ukraine was intermittently flooded as the crust downwarped during much of the Paleozoic, Mesozoic and early Cenozoic, before the formation of the Alps and Carpathian Mountains defined much of its current topography and tectonics. Ukraine was impacted by the Pleistocene glaciations within the last several hundred thousand years. The country has numerous metal deposits as well as minerals, building stone and high-quality industrial sands.
The geology of Kazakhstan includes extensive basement rocks from the Precambrian and widespread Paleozoic rocks, as well as sediments formed in rift basins during the Mesozoic.
The geology of Laos includes poorly defined oldest rocks. Marine conditions persisted for much of the Paleozoic and parts of the Mesozoic, followed by periods of uplift and erosion. The country has extensive salt, gypsum and potash, but very little hydrocarbons and limited base metals.
The geology of Uzbekistan consists of two microcontinents and the remnants of oceanic crust, which fused together into a tectonically complex but resource rich land mass during the Paleozoic, before becoming draped in thick, primarily marine sedimentary units.
The geology of Thailand includes deep crystalline metamorphic basement rocks, overlain by extensive sandstone, limestone, turbidites and some volcanic rocks. The region experienced complicated tectonics during the Paleozoic, long-running shallow water conditions and then renewed uplift and erosion in the past several million years ago.
The geology of Turkmenistan includes two different geological provinces: the Karakum, or South Turan Platform, and the Alpine Orogen.
The geology of Romania is structurally complex, with evidence of past crustal movements and the incorporation of different blocks or platforms to the edge of Europe, driving recent mountain building of the Carpathian Mountains. Romania is a country located at the crossroads of Central, Eastern, and Southeastern Europe. It borders the Black Sea to the southeast, Bulgaria to the south, Ukraine to the north, Hungary to the west, Serbia to the southwest, and Moldova to the east.
The geology of Slovakia is structurally complex, with a highly varied array of mountain ranges and belts largely formed during the Paleozoic, Mesozoic and Cenozoic eras.
The geology of the Czech Republic is very tectonically complex, split between the Western Carpathian Mountains and the Bohemian Massif.
The geology of Iraq includes thick sequences of marine and continental sedimentary rocks over poorly understood basement rock, at the junction of the Arabian Plate, the Anatolian Plate, and the Iranian Plate.
The geology of Italy includes mountain ranges such as the Alps and the Apennines formed from the uplift of igneous and primarily marine sedimentary rocks all formed since the Paleozoic. Some active volcanoes are located in Insular Italy.
The Junggar Basin is one of the largest sedimentary basins in Northwest China. It is located in Xinjiang, and enclosed by the Tarbagatai Mountains of Kazakhstan in the northwest, the Altai Mountains of Mongolia in the northeast, and the Heavenly Mountains in the south. The geology of Junggar Basin mainly consists of sedimentary rocks underlain by igneous and metamorphic basement rocks. The basement of the basin was largely formed during the development of the Pangea supercontinent during complex tectonic events from Precambrian to late Paleozoic time. The basin developed as a series of foreland basins – in other words, basins developing immediately in front of growing mountain ranges – from Permian time to the Quaternary period. The basin's preserved sedimentary records show that the climate during the Mesozoic era was marked by a transition from humid to arid conditions as monsoonal climatic effects waned. The Junggar basin is rich in geological resources due to effects of volcanism and sedimentary deposition. According to Guinness World Records it is a land location remotest from open sea with great-circle distance of 2,648 km from the nearest open sea at 46°16′8″N86°40′2″E.
The Central Asian Orogenic Belt (CAOB), also called the Altaids, is one of the world's largest Phanerozoic accretionary orogens, and thus a leading laboratory of geologically recent crustal growth. The orogenic belt is bounded by the East European Craton and the North China Craton in the Northwest-Southeast direction, as well as Siberia Craton and Tarim Craton in the Northeast-Southwest direction. It formed by ocean closures during Neoproterozoic to the late Phanerozoic time, from around 750 to 150 Ma. Like many other accretionary orogenic belts, the Central Asian Orogenic Belt consists of a huge amount of magmatic arcs, arc-related basins, accretionary complexes, seamounts, continental fragments and ophiolites. It is also considered a relatively distinctive collisional orogenic belt because widespread subduction-accretion complexes and arc magmatic rocks can be found in the region, but collision-related foreland basins are not common.
The geology of the Kimberley, a region of Western Australia, is a rock record of early Proterozoic plate collision, orogeny and suturing between the Kimberley Craton and the Northern Australia Craton, followed by sedimentary basin formation from Proterozoic to Phanerozoic.
