Proto-Tethys Ocean
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The Proto-Tethys or Theic Ocean was an ancient
ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...
that existed from the latest
Ediacaran The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last ...
to the
Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...
(550–330 Ma).


History of concept

The name "Proto-Tethys" has been used inconsistently for several concepts for a supposed predecessor of the
Paleo-Tethys Ocean The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; ex ...
, a palaeocean that separated the margins of
Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
, often referred to as peri-Gondwana, from various continents and Gondwana-derived continental fragments from Precambrian times and onwards. According to , after the Cadomian orogenic events 550 Ma, the Proto-Tethys Ocean formed the eastern part of an oceanic domain (of which the
Iapetus In Greek mythology, Iapetus (; ; ), also Japetus, is a Titan, the son of Uranus and Gaia and father of Atlas, Prometheus, Epimetheus, and Menoetius. He was also called the father of Buphagus and Anchiale in other sources. Iapetus was linked ...
and Tornquist oceans formed the western parts) which subducted under the northern margins of
Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
. In this model the Proto-Tethys separated the
North China North China () is a list of regions of China, geographical region of the People's Republic of China, consisting of five province-level divisions of China, provincial-level administrative divisions, namely the direct-administered municipalities ...
and
Baltica Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, i ...
continents from Gondwana. In the Early Ordovician 500-480 Ma, the Proto-Tethys was subducted under Cadomia as a result of the
Chamrousse Chamrousse () is a ski resort in Southeastern France, in the Belledonne mountain range near Grenoble in the Isère department. It is located in a commune of the same name and is situated on the Recoin at and the Roche Béranger at . The ski ...
back-arc basin A back-arc basin is a type of geologic Structural basin, basin, found at some convergent boundary, convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found ...
. used the name 'Ran Ocean' for a similar concept, the Cambrian-Ordovician ocean that separated Baltica from Gondwana. Other geologists dispute the existence of such an ocean.


Palaeozoic evolution

The ocean formed when
Pannotia Pannotia (from Greek: ''wikt:pan-, pan-'', "all", ''wikt:νότος, -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neo ...
disintegrated, Proto-Laurasia (Laurentia, Baltica, and Siberia) rifted away from a supercontinent that would become
Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
. Proto-Tethys formed between these two supercontinents. The ocean was bordered by Panthalassic Ocean to the north, separating it from Panthalassa by island arcs and
Kazakhstania Kazakhstania (), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia which consists of the area roughly centered on Lake Balkhash, north and east of the Aral Sea, south of the Siberian craton and west of the Alta ...
. The Proto-Tethys expanded during the
Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...
. The ocean was at its widest during the Late
Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...
to Middle
Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...
. The ocean was situated between the
Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...
to the west, and
Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
to the east. The ocean began to shrink during the Late Silurian, when
North China North China () is a list of regions of China, geographical region of the People's Republic of China, consisting of five province-level divisions of China, provincial-level administrative divisions, namely the direct-administered municipalities ...
, and
South China South China ( zh, s=, p=Huá'nán, j=jyut6 naam4) is a geographical and cultural region that covers the southernmost part of China. Its precise meaning varies with context. A notable feature of South China in comparison to the rest of China is ...
moved away from Gondwana and headed north. In the late
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
, the microcontinent of
Kazakhstania Kazakhstania (), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia which consists of the area roughly centered on Lake Balkhash, north and east of the Aral Sea, south of the Siberian craton and west of the Alta ...
collided with Siberia, shrinking the ocean even more. The ocean closed when the North China
craton A craton ( , , or ; from "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of contine ...
collided with Siberia-Kazakstania continent in the
Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...
, while the Paleo-Tethys Ocean expanded.


See also

*
Paleo-Tethys Ocean The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; ex ...
*
Tethys Ocean The Tethys Ocean ( ; ), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era. It was the predecessor to the modern Indian Ocean, the Mediterranean Sea, and the Eurasia ...
*
Rheic Ocean The Rheic Ocean (; ) was an ocean which separated two major paleocontinents, Gondwana and Laurussia ( Laurentia- Baltica- Avalonia). One of the principal oceans of the Paleozoic, its sutures today stretch from Mexico to Turkey and its closure r ...


References


Notes


Sources

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External links


Proto-tethys ocean
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Paleo-Tethys and Proto-Tethys
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– at PaleoMap Project (North China microcontinent begins to collide with Siberia-Kazakstania continent closing the Proto-Tethys) Historical oceans Proterozoic Cambrian paleogeography Ordovician paleogeography Silurian bodies of water Devonian paleogeography Carboniferous paleogeography