View source for Panthalassa

{{short description|Prehistoric superocean that surrounded Pangaea}}
{{About||the Miles Davis album|Panthalassa: The Music of Miles Davis 1969–1974|the Japanese race horse|Panthalassa (horse)}}

[[File:Panthalassa 250Ma.jpg|thumb|upright=1.3|The Panthalassa superocean 250 million years ago]]
[[File:Pangaea 200Ma.jpg|thumb|upright=1.3|The supercontinent [[Pangaea]] in the early Mesozoic (at 200 [[Megaannum|Ma]]) surrounded by Panthalassa.]]
[[File:Pacific Ocean 180Ma.jpg|thumb|upright=1.3|The [[Pacific Plate]] began forming when the [[triple junction]] at the center of Panthalassa destabilized about 190 million years ago.]]
'''Panthalassa''', also known as the '''Panthalassic Ocean''' or '''Panthalassan Ocean''' (from [[Ancient Greek|Greek]] {{lang|grc|[[wikt:πᾶν|πᾶν]]}} "all" and {{lang|grc|[[wikt:θάλασσα#Ancient Greek|θάλασσα]]}} "sea"),<ref name=OnlineEtDict>{{cite web|title=Panthalassa|url=http://www.etymonline.com/index.php?term=Panthalassa&allowed_in_frame=0|publisher=[[Online Etymology Dictionary]]}}</ref> was the vast [[superocean]] that encompassed planet [[Earth]] and surrounded the [[supercontinent]] [[Pangaea]], the latest in a series of supercontinents in the [[history of Earth]]. During the [[Paleozoic]]–[[Mesozoic]] transition ({{Circa}} 250&nbsp;{{abbr|Ma|million years ago}}), the ocean occupied almost 70% of Earth's surface, with the supercontinent Pangaea taking up the remaining one third. The original, ancient [[ocean floor]] has now completely disappeared because of the continuous [[subduction]] along the [[continental margin]]s on its circumference.<ref>{{Harvnb|Isozaki|2014|loc=Permo–Triassic Boundary Superanoxia and Extinction, pp. 290–291}}</ref> Panthalassa is also referred to as the '''Paleo-Pacific''' ("old Pacific") or '''Proto-Pacific''' because the [[Pacific Ocean]] is a direct continuation of Panthalassa.

==Formation==

The supercontinent [[Rodinia]] began to break up 870–845&nbsp;{{abbr|Ma|million years ago}} probably as a consequence of a [[Large low-shear-velocity provinces|superplume]] caused by mantle slab avalanches along the margins of the supercontinent. In a second episode {{Circa}} 750&nbsp;{{abbr|Ma|million years ago}} the western half of Rodinia started to rift apart: western [[Kalahari craton|Kalahari]] and [[South China (continent)|South China]] broke away from the western margins of [[Laurentia]]; and by 720&nbsp;{{abbr|Ma|million years ago}} Australia and East Antarctica had also separated.<ref>{{Harvnb|Li|Bogdanova|Collins|Davidson|2008|loc=Superplume events, continental rifting, and the prolonged break-up process of Rodinia (ca. 860–570 Ma), pp. 199–201}}</ref> In the Early Jurassic the Pacific Plate opened originating from a [[triple junction]] between the Panthalassic [[Farallon Plate|Farallon]], [[Phoenix Plate|Phoenix]], and [[Izanagi Plate|Izanagi]] plates. Panthalassa can be reconstructed based on magnetic lineations and fracture zones preserved in the western Pacific.<ref name="Seton-Müller-intro">{{Harvnb|Seton|Müller|2008|loc=Introduction, p. 263}}</ref>

== Reconstruction of ocean basin ==
Most of the oceanic plates that formed the ocean floor of Panthalassa have been subducted and so traditional plate tectonic reconstructions based on [[Magnetic anomaly|magnetic anomalies]] can therefore be used only for remains from the Cretaceous and later. The former margins of the ocean, however, contain [[allochthon]]ous [[terrane]]s with preserved Triassic–Jurassic intra-Panthalassic volcanic arcs, including Kolyma–Omolon (northeast Asia), Anadyr–Koryak (east Asia), Oku–Niikappu (Japan), and [[Wrangellia Terrane|Wrangellia]] and [[Stikinia]] (western North America).
Furthermore, [[seismic tomography]] is being used to identify subducted slabs in the mantle from which the location of former Panthalassic subduction zones can be derived. A series of such subduction zones, called Telkhinia, defines two separate oceans or systems of oceanic plates—the Pontus and Thalassa oceans.<ref>{{Harvnb|Van der Meer|Torsvik|Spakman|Van Hinsbergen|2012|p=215}}</ref>
Named marginal oceans or oceanic plates include (clockwise) [[Mongol-Okhotsk Ocean|Mongol-Okhotsk]] (now a [[Suture (geology)|suture]] between Mongolia and Sea of Okhotsk), Oimyakon (between Asian craton and Kolyma-Omolon), [[Slide Mountain Ocean]] (British Columbia),<ref name=N2000>{{Harvnb|Nokleberg|Parfenov|Monger|Norton|2000}}</ref> and [[Mezcalera Ocean|Mezcalera]] (western Mexico).

===Eastern margin===
The eastern margin of the ocean coincided with the western margin (modern coordinates) of the continent Laurentia. The western margin  of Laurentia originated during the Neoproterozoic break-up of Rodinia. The [[North American Cordillera]] is an accretionary [[orogen]], which grew by the progressive addition of allochthonous terranes along this margin from the Late Palaeozoic. Devonian back-arc volcanism reveals how this eastern Panthalassic margin developed in the mid-Paleozoic into the [[Convergent boundary|active margin]] it still is today.

Most of the [[continental fragment]]s, [[volcanic arc]]s, and [[Oceanic basin|ocean basins]] added to Laurentia this way contained faunas of Tethyan or Asian affinity. Similar terranes added to the northern Laurentia, in contrast, have affinities with Baltica, Siberia, and the northern [[Caledonian orogeny|Caledonies]]. The latter terranes were probably accreted along the eastern Panthalassa margin by a [[Caribbean Plate|Caribbean]]–[[Scotia Plate|Scotia]]-style subduction system.<ref>{{Harvnb|Colpron|Nelson|2009|pp=273–275}}</ref>

===Western margin===
The evolution of the Panthalassa–Tethys boundary is poorly known because little oceanic crust is preserved—both the Izanagi and the conjugate Pacific Ocean floor is subducted and the ocean ridge that separated them probably subducted {{Circa}} 60–55&nbsp;{{abbr|Ma|million years ago}}. Today, the region is dominated by the collision of the [[Australian Plate]] with a complex network of plate boundaries in south-east Asia, including the [[Sundaland]] block. Spreading along the Pacific-Phoenix ridge ended 83&nbsp;Ma at the Osbourn Trough at the [[Tonga Trench|Tonga]]-[[Kermadec Trench]].<ref name="Seton-Müller-intro" />

During the Permian, [[atoll]]s developed near the Equator on the mid-Panthalassic seamounts. As Panthalassa subducted along its western margin during the Triassic and Early Jurassic, those seamounts and palaeo-atolls were [[Accretion (geology)|accreted]] as allochthonous limestone blocks and fragments along the Asian margin.<ref>{{Harvnb|Kani|Hisanabe|Isozaki|2013|loc=Geologic setting, p. 213}}</ref> One such migrating atoll complex now form a {{Convert|2|km|mi|adj=mid|spell=in|-long}} and {{Convert|100|to(-)|150|m|ft|adj=mid|-wide}} body of limestone in central [[Kyushu]], south-west Japan.<ref>{{Harvnb|Kasuya|Isozaki|Igo|2012|loc=Geological Setting, p. 612}}</ref>

[[Fusulinida|Fusuline]] [[foraminifera]], a now extinct order of single-celled organisms, diversified extensively and developed [[gigantism]]—the genus ''Eopolydiexodina'', for example, reached up to {{Convert|16|cm|abbr=on}} in size—and structural sophistication, including symbiont relationships with photosynthesising algae, during the Late Carboniferous and Permian,<ref name="Groves2009Foraminifera">{{cite journal |last1=Groves |first1=John R. |last2=Yue |first2=Wang |date=1 September 2009 |title=Foraminiferal diversification during the late Paleozoic ice age |url=https://bioone.org/journals/paleobiology/volume-35/issue-3/0094-8373-35.3.367/Foraminiferal-diversification-during-the-late-Paleozoic-ice-age/10.1666/0094-8373-35.3.367.short |journal=Paleobiology |volume=35 |issue=3 |pages=367–392 |doi=10.1666/0094-8373-35.3.367 |bibcode=2009Pbio...35..367G |s2cid=130097035 |access-date=4 September 2022|url-access=subscription }}</ref> in what is known as the [[Carboniferous-Earliest Permian Biodiversification Event]].<ref name="CPBE">{{cite journal |last1=Shi |first1=Yukun |last2=Wang |first2=Xiangdong |last3=Fan |first3=Junxuan |last4=Huang |first4=Hao |last5=Xu |first5=Huiqing |last6=Zhao |first6=Yingying |last7=Shen |first7=Shuzhong |date=September 2021 |title=Carboniferous-earliest Permian marine biodiversification event (CPBE) during the Late Paleozoic Ice Age |url=https://www.sciencedirect.com/science/article/pii/S0012825221002002 |journal=Earth-Science Reviews |volume=220 |article-number=103699 |doi=10.1016/j.earscirev.2021.103699 |bibcode=2021ESRv..22003699S |access-date=4 September 2022|url-access=subscription }}</ref> The Capitanian mass extinction event {{Circa}} 260&nbsp;{{abbr|Ma|million years ago}}, however, put an end to that development, with only dwarf taxa persisting throughout the Permian until the final fusuline extinction in the [[Permian-Triassic extinction event|Great Dying]] {{Circa}} 252&nbsp;{{abbr|Ma|million years ago}}. Permian fusulines also developed a remarkable provincialism by which fusulines can be grouped into six domains.<ref>{{Harvnb|Kasuya|Isozaki|Igo|2012|loc=Introduction, pp. 611–612}}</ref>
Because of the large size of Panthalassa, a hundred million years could separate the accretion of different groups of fusulines. Assuming a minimum accretion rate of {{convert|3|cm/year}}, the seamount chains on which those groups evolved would be separated by at least {{Convert|3000|km|abbr=on}}. Those groups apparently evolved in completely different environments.<ref>{{Harvnb|Kasuya|Isozaki|Igo|2012|loc=Migrating seamounts and fusuline territories in Panthalassa, pp. 620–621}}</ref>

A significant sea-level drop at the end of the Permian led to the [[end-Capitanian extinction event]]. The cause for the extinction is disputed, but a likely candidate is an episode of global cooling, which transformed a large amount of sea-water into continental ice.<ref>{{Harvnb|Kofukuda|Isozaki|Igo|2014|loc=Global cooling as a possible cause, p. 64}}</ref>

Seamounts accreted in eastern Australia as parts of the [[Hunter-Bowen orogeny|New England orogen]] reveal the [[Hotspot (geology)|hotspot]] history of Panthalassa.<ref>{{Harvnb|Flood|1999|loc=Abstract}}</ref> From the Late Devonian to the Carboniferous, Gondwana and Panthalassa converged along the eastern margin of Australia along a west-dipping subduction system, which produced (west to east) a magmatic arc, a [[forearc]] basin, and an accretionary wedge. Subduction ceased along that margin in the Late Carboniferous and jumped eastward. From the Late Carboniferous to the [[Cisuralian|Early Permian]] the New England orogen was dominated by an extensional setting related to a subduction to strike-slip transition. Subduction was re-initiated in the Permian and the granitic rocks of the New England [[Batholith]] were produced by a magmatic arc, indicating the presence of an active plate margin along most of the [[Orogeny|orogen]]. Permian to Cretaceous remains of the convergent margin, preserved as fragments in [[Zealandia]] ([[New Zealand]], [[New Caledonia]], and the [[Lord Howe Rise]]), were rifted off Australia during the Late Cretaceous to Early Tertiary break-up of eastern Gondwana and the opening of the [[Tasman Sea]].<ref>{{Harvnb|Waschbusch|Beaumont|Korsch|1999|loc=Tectonic setting of the New England orogen and adjacent basins, pp. 204–206}}</ref>

The [[Cretaceous]] Junction Plate, located north of Australia, separated the eastern [[Tethys Ocean|Tethys]] from Panthalassa.<ref>{{Harvnb|Talsma|Müller|Bunge|Seton|2010}}</ref>

==Palaeo-oceanography==
Panthalassa was a hemisphere-sized ocean, much larger than the modern Pacific. It could be expected that the large size would result in relatively simple ocean current circulation patterns, such as a single gyre in each hemisphere, and a mostly stagnant and stratified ocean. Modelling studies, however, suggest that an east–west [[sea surface temperature]] (SST) gradient was present in which the coldest water was brought to the surface by [[upwelling]] in the east while the warmest water extended west into the Tethys Ocean.
Subtropical gyres dominated the circulation pattern. The two hemispherical belts were separated by the undulating [[Intertropical Convergence Zone]] (ITCZ).<ref name="Arias-p3">{{Harvnb|Arias|2008|loc=The Panthalassa Ocean, pp. 3–5}}</ref>

In northern Panthalassa, there were mid-latitude westerlies north of 60°N with easterlies between 60°N and the Equator. Atmospheric circulation north of 30°N is associated with the North Panthalassa High, which created [[Ekman transport|Ekman convergence]] between 15°N and 50°N and Ekman divergence between 5°N and 10°N. A pattern developed that resulted in [[Sverdrup balance|Sverdrup transport]] that went northward in divergence regions and southward in convergence regions. Western boundary currents resulted in an anti-cyclonic subtropical North Panthalassa gyre at mid-latitudes and a meridional anti-cyclonic circulation centred on 20°N.<ref name="Arias-p3" />

In tropical northern Panthalassa, trade winds created westward flows while equatorward flows were created by westerlies at higher latitudes. Consequently, trade winds moved water away from Gondwana towards Laurasia in the northern Panthalassa Equatorial Current. When the western margins of Panthalassa were reached, intense western boundary currents would form the Eastern Laurasia Current. At mid-latitudes, the North Panthalassa Current would bring the water back east where a weak Northwestern Gondwana Current would finally close the gyre. The accumulation of water along the western margin, coupled with the [[Coriolis force|Coriolis effect]], would have created a Panthalassa Equatorial Counter Current.<ref name="Arias-p3" />

In the southern Panthalassa, the four currents of the subtropical gyre, the South Panthalassa Gyre, rotated counterclockwise. The South Equatorial Panthalassa Current flowed westward between the Equator and 10°S into the western, intense South Panthalassa Current. The South Polar Current then completed the gyre as the Southwestern Gondwana Current. Near the poles easterlies created a subpolar gyre that rotated clockwise.<ref name="Arias-p3" />

==See also==
{{portal|Oceans}}
* {{annotated link|Ring of Fire}}
* {{annotated link|Paleontology}}
* {{annotated link|Plate tectonics}}

==References==
{{Reflist|30em}}

==Sources==
{{Refbegin|30em}}
* {{Cite journal
 | last = Arias | first = C.
 | title = Palaeoceanography and biogeography in the Early Jurassic Panthalassa and Tethys oceans
 | year = 2008 | journal = Gondwana Research | volume = 14 | issue = 3 | pages = 306–315
 | url = http://eprints.sim.ucm.es/12212/1/Arias__2008_1.pdf | access-date = 27 December 2016
 | doi = 10.1016/j.gr.2008.03.004 | bibcode = 2008GondR..14..306A
 }}<!-- {{Harvnb|Arias|2008}} -->
* {{Cite journal
 | last1 = Colpron | first1 = M.
 | last2 = Nelson | first2 = J. L.
 | title = A Palaeozoic Northwest Passage: Incursion of Caledonian, Baltican and Siberian terranes into eastern Panthalassa, and the early evolution of the North American Cordillera
 | year = 2009 | journal = Geological Society, London, Special Publications | volume = 318 | issue = 1 | pages = 273–307
 | url = http://www.em.gov.bc.ca/Mining/Geoscience/Staff/Documents/2009_NW_Passage.pdf | access-date = 28 December 2016
 | doi = 10.1144/SP318.10 | bibcode = 2009GSLSP.318..273C
 | s2cid = 128635186
 }}<!-- {{Harvnb|Colpron|Nelson|2009}} -->
* {{Cite conference
 | last1 = Flood | first1 = P. G.
 | title = Exotic seamounts within Gondwanan accretionary complexes, Eastern Australia
 | year = 1999 | conference = Regional geology, tectonics and metallogenesis: New England orogen | location = University of New England, Armidale | pages = 23–29
 | url = https://www.researchgate.net/publication/237842579 | access-date = 28 December 2016
 }}<!-- {{Harvnb|Flood|1999}} -->
* {{Cite journal
 | last = Isozaki | first = Y.
 | title = Memories of Pre-Jurassic Lost Oceans: How To Retrieve Them From Extant Lands
 | year = 2014 | journal = Geoscience Canada | volume = 41 | issue = 3 | pages = 283–311
 | doi = 10.12789/geocanj.2014.41.050 | citeseerx = 10.1.1.1001.9743
 }}<!-- {{Harvnb|Isozaki|2014}} -->
* {{Cite journal
 | last1 = Kani | first1 = T.
 | last2 = Hisanabe | first2 = C.
 | last3 = Isozaki | first3 = Y.
 | title = The Capitanian (Permian) minimum of <sup>87</sup>Sr/<sup>86</sup>Sr ratio in the mid-Panthalassan paleo-atoll carbonates and its demise by the deglaciation and continental doming
 | year = 2013 | journal = Gondwana Research | volume = 24 | issue = 1 | pages = 212–221
 | url = https://www.researchgate.net/publication/257517884 | access-date = 28 December 2016
 | doi = 10.1016/j.gr.2012.08.025 | bibcode = 2013GondR..24..212K
 }}<!-- {{Harvnb|Kani|Hisanabe|Isozaki|2013}} -->
* {{Cite journal
 | last1 = Kasuya | first1 = A.
 | last2 = Isozaki | first2 = Y.
 | last3 = Igo | first3 = H.
 | title = Constraining paleo-latitude of a biogeographic boundary in mid-Panthalassa: Fusuline province shift on the Late Guadalupian (Permian) migrating seamount
 | year = 2012 | journal = Gondwana Research | volume = 21 | issue = 2 | pages = 611–623
 | url = http://ea.c.u-tokyo.ac.jp/earth/Members/Isozaki/12Kasuya-GR.pdf | access-date = 28 December 2016
 | doi = 10.1016/j.gr.2011.06.001 | bibcode = 2012GondR..21..611K
 }}<!-- {{Harvnb|Kasuya|Isozaki|Igo|2012}} -->
* {{Cite journal
 | last1 = Kofukuda | first1 = D.
 | last2 = Isozaki | first2 = Y.
 | last3 = Igo | first3 = H.
 | title = A remarkable sea-level drop and relevant biotic responses across the Guadalupian–Lopingian (Permian) boundary in low-latitude mid-Panthalassa: Irreversible changes recorded in accreted paleo-atoll limestones in Akasaka and Ishiyama, Japan
 | year = 2014 | journal = Journal of Asian Earth Sciences | volume = 82 | pages = 47–65
 | url = https://www.researchgate.net/publication/260009345 | access-date = 28 December 2016
 | doi = 10.1016/j.jseaes.2013.12.010 | bibcode = 2014JAESc..82...47K
 }}<!-- {{Harvnb|Kofukuda|Isozaki|Igo|2014}} -->
* {{Cite journal
 | last1 = Li | first1 = Z. X.
 | last2 = Bogdanova | first2 = S. V.
 | last3 = Collins | first3 = A. S.
 | last4 = Davidson | first4 = A.
 | last5 = De Waele | first5 = B.
 | last6 = Ernst | first6 = R. E.
 | last7 = Fitzsimons | first7 = I. C. W.
 | last8 = Fuck | first8 = R. A.
 | last9 = Gladkochub | first9= D. P.
 | last10 = Jacobs | first10 = J.
 | last11 = Karlstrom | first11 = K. E.
 | last12 = Lul | first12 = S.
 | last13 = Natapov | first13 = L. M.
 | last14 = Pease | first14 = V.
 | last15 = Pisarevsky | first15 = S. A.
 | last16 = Thrane | first16 = K.
 | last17 = Vernikovsky | first17 = V.
 | title = Assembly, configuration, and break-up history of Rodinia: A synthesis
 | year = 2008 | journal = Precambrian Research | volume = 160 | issue = 1–2
 | pages = 179–210
 | url = http://www.bdewaele.be/pdfs/Lietal_IGCP440_map_2008.pdf | access-date = 6 February 2016
 | doi = 10.1016/j.precamres.2007.04.021 | bibcode = 2008PreR..160..179L
 }}<!-- {{Harvnb|Li|Bogdanova|Collins|Davidson|2008}} -->
* {{Cite journal
 | last1 = Nokleberg | first1 = W. J.
 | last2 = Parfenov | first2 = L. M.
 | last3 = Monger | first3 = J. W. H.
 | last4 = Norton | first4 = I. O.
 | last5 = Khanchuk | first5 = A. I.
 | last6 = Stone | first6 = D. B.
 | last7 = Scotese | first7 = C. R.
 | last8 = Scholl | first8 = D. W.
 | last9 = Fujita | first9 = K.
 | title = Phanerozoic tectonic evolution of the circum-north Pacific
 | year = 2000 | journal = USGS 231 Professional Paper | volume = 1626 | pages = 1–122
 | url = https://pubs.usgs.gov/pp/2000/1626/pp1626.pdf | access-date = 27 December 2016
 }}<!-- {{Harvnb|Nokleberg|Parfenov|Monger|Norton|2000}} -->
* {{Cite conference
 | last1 = Seton | first1 = M.
 | last2 = Müller | first2 = R. D.
 | title = Reconstructing the junction between Panthalassa and Tethys since the Early Cretaceous
 | year = 2008 | conference = Eastern Australasian Basins III | publisher = Petroleum Exploration Society of Australia, Special Publications | location = Sydney | pages = 263–266
 | url = https://www.researchgate.net/publication/232095770 | access-date = 27 December 2016
 }}<!-- {{Harvnb|Seton|Müller|2008}} -->
* {{Cite journal
 | last1 = Talsma | first1 = A. S.
 | last2 = Müller | first2 = R. D.
 | last3 = Bunge | first3 = H.-P.
 | last4 = Seton | first4 = M.
 | title = The Geodynamic Evolution of the Junction Plate: Linking observations to high-resolution models
 | year = 2010 | journal = 4th EResearch Australasia Conference
 | url = http://earthbyte.org/Resources/Pdf/Talsma_eresearch_Brisbane_2010.pdf | access-date = 27 December 2016
 }}<!-- {{Harvnb|Talsma|Müller|Bunge|Seton|2010}} -->
* {{Cite journal
 | last1 = Van der Meer | first1 = D. G.
 | last2 = Torsvik | first2 = T. H.
 | last3 = Spakman | first3 = W.
 | last4 = Van Hinsbergen | first4 = D. J. J.
 | last5 = Amaru | first5 = M. L.
 | title = Intra-Panthalassa Ocean subduction zones revealed by fossil arcs and mantle structure
 | year = 2012 | journal = [[Nature Geoscience]] | volume = 5 | issue = 3 | pages = 215–219
 | url = http://www.geologist.nl/images/2012_vanderMeer_NatGeo.pdf | access-date = 27 December 2016
 | doi = 10.1038/ngeo1401 | bibcode = 2012NatGe...5..215V
 }}<!-- {{Harvnb|Van der Meer|Torsvik|Spakman|Van Hinsbergen|2012}} -->
* {{Cite conference
 | last1 = Waschbusch | first1 = P.
 | last2 = Beaumont | first2 = C.
 | last3 = Korsch | first3 = R. J.
 | title = Geodynamic modelling of aspects of the New England Orogen and adjacent Bowen, Gunnedah and Surat basins
 | year = 1999 | conference = Regional geology, tectonics and metallogenesis: New England orogen | location = University of New England, Armidale | pages = 203–210
 | url = https://www.researchgate.net/publication/237842579 | access-date = 28 December 2016
 }}<!-- {{Harvnb|Waschbusch|Beaumont|Korsch|1999}} -->
{{Refend}}

==External links==
* {{Cite web
 | title = Early Triassic | publisher = Paleomap project | date = 24 January 2001
 | url = http://scotese.com/newpage8.htm | access-date = 27 December 2016}}

[[Category:Plate tectonics]]
[[Category:Historical oceans]]
[[Category:Paleozoic paleogeography]]
[[Category:Mesozoic paleogeography]]