Editing Devonian (section)

==Paleogeography==
The Devonian world involved many continents and ocean basins of various sizes. The largest continent, [[Gondwana]], was located entirely within the [[Southern Hemisphere]]. It corresponds to modern day [[South America]], [[Africa]], [[Australia]], [[Antarctica]], and [[India]], as well as minor components of [[North America]] and [[Asia]]. The second-largest continent, Laurussia, was northwest of Gondwana, and corresponds to much of modern-day [[North America]] and [[Europe]]. Various smaller continents, [[microcontinents]], and [[terrane]]s were present east of Laurussia and north of Gondwana, corresponding to parts of Europe and Asia. The Devonian Period was a time of great [[plate tectonics|tectonic]] activity, as the major continents of [[Laurussia]] and [[Gondwana]] drew closer together.<ref name="Cocks-2016">{{Citation |title=Devonian |date=2016 |url=https://www.cambridge.org/core/books/earth-history-and-palaeogeography/devonian/56EB82A628FA7B830FEB1F9A8E5DF77F |work=Earth History and Palaeogeography |pages=138–158 |editor-last=Cocks |editor-first=L. Robin M. |place=Cambridge |publisher=Cambridge University Press |doi=10.1017/9781316225523.009 |isbn=978-1-316-22552-3 |access-date=2022-07-24 |editor2-last=Torsvik |editor2-first=Trond H.|url-access=subscription }}</ref><ref name="Golonka-2020">{{Cite journal |last=Golonka |first=Jan |date=2020-03-01 |title=Late Devonian paleogeography in the framework of global plate tectonics |url=https://www.sciencedirect.com/science/article/pii/S0921818120300187 |journal=Global and Planetary Change |language=en |volume=186 |pages=103129 |doi=10.1016/j.gloplacha.2020.103129 |bibcode=2020GPC...18603129G |s2cid=212928195 |issn=0921-8181|url-access=subscription }}</ref>

Sea levels were high worldwide, and much of the land lay under shallow seas, where tropical [[reef]] organisms lived. The enormous "world ocean", [[Panthalassa]], occupied much of the [[Northern Hemisphere]] as well as wide swathes east of Gondwana and west of Laurussia. Other minor oceans were the [[Paleo-Tethys Ocean]] and [[Rheic Ocean]].<ref name="Cocks-2016" /><ref name="Golonka-2020" />

=== Laurussia ===
[[File:Laurussia Euramerica.svg|thumb|263x263px|Continental boundary of [[Laurussia]] (Euramerica) and its constituents, superimposed onto modern coastlines]]
By the early Devonian, the continent Laurussia (also known as [[Euramerica]]) was fully formed through the collision of the continents [[Laurentia]] (modern day North America) and [[Baltica]] (modern day northern and eastern Europe). The tectonic effects of this collision continued into the Devonian, producing a string of mountain ranges along the southeastern coast of the continent. In present-day eastern North America, the [[Acadian orogeny|Acadian Orogeny]] continued to raise the [[Appalachian Mountains]]. Further east, the collision also extended the rise of the [[Caledonian orogeny|Caledonian Mountains]] of [[Great Britain]] and [[Scandinavia]]. As the Caledonian Orogeny wound down in the later part of the period, [[orogenic collapse]] facilitated a cluster of granite intrusions in Scotland.<ref name="Cocks-2016" />

Most of Laurussia was located south of the equator, but in the Devonian it moved northwards and began to rotate counterclockwise towards its modern position. While the most northern parts of the continent (such as [[Greenland]] and [[Ellesmere Island]]) established tropical conditions, most of the continent was located within the natural dry zone along the [[Tropic of Capricorn]], which (as nowadays) is a result of the convergence of two great air-masses, the [[Hadley cell]] and the [[Ferrel cell]]. In these near-deserts, the [[Old Red Sandstone]] sedimentary beds formed, made red by the oxidised iron ([[hematite]]) characteristic of drought conditions. The abundance of red sandstone on continental land also lends Laurussia the name "the Old Red Continent".<ref>{{Cite encyclopedia |url=https://www.britannica.com/science/Devonian-Period |title=Devonian Period |series=geochronology |encyclopedia=Encyclopedia Britannica |access-date=2017-12-15 |df=dmy-all |language=en}}</ref> For much of the Devonian, the majority of western Laurussia (North America) was covered by subtropical [[Inland sea (geology)|inland seas]] which hosted a diverse ecosystem of reefs and marine life. Devonian marine deposits are particularly prevalent in the [[Midwestern United States|midwestern]] and [[Northeastern United States|northeastern]] United States. Devonian reefs also extended along the southeast edge of Laurussia, a coastline now corresponding to southern [[England]], [[Belgium]], and other mid-latitude areas of Europe.<ref name="Cocks-2016" />

In the Early and Middle Devonian, the west coast of Laurussia was a passive margin with broad coastal waters, deep silty embayments, river deltas and estuaries, found today in [[Idaho]] and [[Nevada]]. In the Late Devonian, an approaching volcanic [[island arc]] reached the steep slope of the continental shelf and began to uplift deep water deposits. This minor collision sparked the start of a mountain-building episode called the [[Antler orogeny]], which extended into the Carboniferous.<ref name="Cocks-2016" /><ref>{{cite web |url=http://jan.ucc.nau.edu/~rcb7/devpaleo.html |archive-url=https://web.archive.org/web/20100415135733/http://jan.ucc.nau.edu/~rcb7/devpaleo.html |title=Devonian Paleogeography, Southwestern US |archive-date=April 15, 2010 |last=Blakey |first=Ron C. |website=jan.ucc.nau.edu |url-status=dead |publisher=Northern Arizona University |df=dmy-all}}</ref> Mountain building could also be found in the far northeastern extent of the continent, as minor tropical island arcs and detached Baltic terranes re-join the continent. Deformed remnants of these mountains can still be found on Ellesmere Island and [[Svalbard]]. Many of the Devonian collisions in Laurussia produce both mountain chains and [[foreland basin]]s, which are frequently fossiliferous.<ref name="Cocks-2016" /><ref name="Golonka-2020" />

=== Gondwana ===
[[File:Early-Middle Devonian chasmataspids paleogeography.png|left|thumb|306x306px|The Early-Middle Devonian world, with major continents Gondwana (Go), Euramerica/Laurussia (Eu), and Siberia (Si)]]
Gondwana was by far the largest continent on the planet. It was completely south of the equator, although the northeastern sector (now Australia) did reach tropical latitudes. The southwestern sector (now South America) was located to the far south, with [[Brazil]] situated near the [[South Pole]]. The northwestern edge of Gondwana was an [[active margin]] for much of the Devonian, and saw the [[Accretion (geology)|accretion]] of many smaller land masses and island arcs. These include [[Chilenia]], [[Cuyania]], and [[Chaitenia]], which now form much of [[Chile]] and [[Tectonic evolution of Patagonia|Patagonia]].<ref name="Cocks-2016" /><ref name="Herve2018">{{cite journal |last1=Hervé |first1=Francisco|author-link1=Francisco Hervé |last2=Calderón |first2=Mauricio |last3=Fanning |first3=Mark |last4=Pankhurst |first4=Robert|author-link4=Robert John Pankhurst |last5=Rapela |first5=Carlos W. |last6=Quezada |first6=Paulo |year=2018 |title=The country rocks of Devonian magmatism in the North Patagonian Massif and Chaitenia |url=http://www.andeangeology.cl/index.php/revista1/article/view/V45n3-3117 |journal=[[Andean Geology]] |volume=45 |issue=3 |pages=301–317 |doi=10.5027/andgeoV45n3-3117|doi-access=free |bibcode=2018AndGe..45..301H |hdl=11336/81577 |hdl-access=free }}</ref> These collisions were associated with [[volcanic activity]] and [[plutons]], but by the Late Devonian the tectonic situation had relaxed and much of South America was covered by shallow seas. These south polar seas hosted a distinctive brachiopod fauna, the Malvinokaffric Realm, which extended eastward to marginal areas now equivalent to South Africa and Antarctica. Malvinokaffric faunas even managed to approach the South Pole via a tongue of Panthalassa which extended into the [[Paraná Basin]].<ref name="Cocks-2016" />

The northern rim of Gondwana was mostly a passive margin, hosting extensive marine deposits in areas such as northwest Africa and [[Tibet]]. The eastern margin, though warmer than the west, was equally active. Numerous mountain building events and [[granite]] and [[kimberlite]] intrusions affected areas equivalent to modern day eastern [[Australia]], [[Tasmania]], and Antarctica.<ref name="Cocks-2016" />

=== Asian terranes ===
[[File:380 Ma plate tectonic reconstruction.png|thumb|200px|The earth at 380 Ma, centered on the [[Paleo-Tethys Ocean]], which fully opened during the Devonian]]Several island microcontinents (which would later coalesce into modern day Asia) stretched over a low-latitude [[archipelago]] to the north of Gondwana. They were separated from the southern continent by an oceanic basin: the [[Paleo-Tethys Ocean|Paleo-Tethys]]. Although the western Paleo-Tethys Ocean had existed since the Cambrian, the eastern part only began to rift apart as late as the Silurian. This process accelerated in the Devonian. The eastern branch of the Paleo-Tethys was fully opened when [[South China craton|South China]] and [[Annamia block|Annamia]] (a [[terrane]] equivalent to most of [[Indochina]]), together as a unified continent, detached from the northeastern sector of Gondwana. Nevertheless, they remained close enough to Gondwana that their Devonian fossils were more closely related to Australian species than to north Asian species. Other Asian terranes remained attached to Gondwana, including [[Sibumasu]] (western Indochina), Tibet, and the rest of the [[Cimmeria (continent)|Cimmerian]] blocks.<ref name="Cocks-2016" /><ref name="Golonka-2020" />
[[File:Nostolepis distribution Early Devonian paleogeography.png|left|thumb|288x288px|World map at 400 Ma (Early Devonian), showing continents and [[terrane]]s with modern continent borders superimposed]]
While the South China-Annamia continent was the newest addition to the Asian microcontinents, it was not the first. [[North China craton|North China]] and the [[Tarim Block]] (now northwesternmost China) were located westward and continued to drift northwards, powering over older oceanic crust in the process. Further west was a small ocean (the Turkestan Ocean), followed by the larger microcontinents of [[Kazakhstania]], [[Siberia (continent)|Siberia]], and [[Amurian Plate|Amuria]]. Kazakhstania was a volcanically active region during the Devonian, as it continued to assimilate smaller island arcs.<ref name="Cocks-2016" /> The island arcs of the region, such as the Balkhash-West Junggar Arc, exhibited biological endemism as a consequence of their location.<ref>{{Cite journal |last1=Wang |first1=Z. H. |last2=Becker |first2=R. T. |last3=Aboussalam |first3=Z. S. |last4=Hartenfels |first4=S. |last5=Joachimski |first5=Michael M. |last6=Gong |first6=Y. M. |date=15 April 2016 |title=Conodont and carbon isotope stratigraphy near the Frasnian/Famennian (Devonian) boundary at Wulankeshun, Junggar Basin, NW China |url=https://www.sciencedirect.com/science/article/pii/S0031018215007646 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |series=Ecosystem evolution in deep time: evidence from the rich Palaeozoic fossil records of China |volume=448 |pages=279–297 |doi=10.1016/j.palaeo.2015.12.029 |bibcode=2016PPP...448..279W |issn=0031-0182 |access-date=11 November 2023|url-access=subscription }}</ref>

Siberia was located just north of the equator as the largest landmass in the Northern Hemisphere. At the beginning of the Devonian, Siberia was inverted (upside down) relative to its modern orientation. Later in the period it moved northwards and began to twist clockwise, though it was not near its modern location. Siberia approached the eastern edge of Laurussia as the Devonian progressed, but it was still separated by a seaway, the [[Ural Ocean]]. Although Siberia's margins were generally tectonically stable and ecologically productive, rifting and deep [[mantle plume]]s impacted the continent with [[flood basalt]]s during the Late Devonian. The [[Altai-Sayan region]] was shaken by volcanism in the Early and Middle Devonian, while Late Devonian magmatism was magnified further to produce the [[Vilyuy Traps]], flood basalts which may have contributed to the Late Devonian Mass Extinction. The last major round of volcanism, the Yakutsk Large Igneous Province, continued into the Carboniferous to produce extensive kimberlite deposits.<ref name="Cocks-2016" /><ref name="Golonka-2020" />

Similar volcanic activity also affected the nearby microcontinent of Amuria (now [[Manchuria]], [[Mongolia]] and their vicinities). Though certainly close to Siberia in the Devonian, the precise location of Amuria is uncertain due to contradictory [[Paleomagnetism|paleomagnetic]] data.<ref name="Cocks-2016" />

=== Closure of the Rheic Ocean ===
The Rheic Ocean, which separated Laurussia from Gondwana, was wide at the start of the Devonian, having formed after the drift of [[Avalonia]] away from Gondwana. It steadily shrunk as the period continued, as the two major continents approached near the [[equator]] in the early stages of the assembly of [[Pangaea]]. The closure of the Rheic Ocean began in the Devonian and continued into the Carboniferous. As the ocean narrowed, endemic marine faunas of Gondwana and Laurussia combined into a single tropical fauna. The history of the western Rheic Ocean is a subject of debate, but there is good evidence that Rheic oceanic crust experienced intense [[subduction]] and [[metamorphism]] under Mexico and Central America.<ref name="Cocks-2016" /><ref name="Golonka-2020" />

The closure of the eastern part of the Rheic Ocean is associated with the assemblage of central and southern Europe. In the early Paleozoic, much of Europe was still attached to Gondwana, including the terranes of [[Iberia]], [[Armorican terrane|Armorica]] (France), [[Palaeo-Adria]] (the western Mediterranean area), [[Bohemia]], [[Franconia]], and [[Saxothuringian Zone|Saxothuringia]]. These continental blocks, collectively known as the Armorican Terrane Assemblage, split away from Gondwana in the Silurian and drifted towards Laurussia through the Devonian. Their collision with Laurussia leads to the beginning of the [[Variscan orogeny|Variscan Orogeny]], a major mountain-building event which would escalate further in the Late Paleozoic. Franconia and Saxothuringia collided with Laurussia near the end of the Early Devonian, pinching out the easternmost Rheic Ocean. The rest of the Armorican terranes followed, and by the end of the Devonian they were fully connected with Laurussia. This sequence of rifting and collision events led to the successive creation and destruction of several small seaways, including the Rheno-Hercynian, Saxo-Thuringian, and Galicia-Moldanubian oceans. Their sediments were eventually compressed and completely buried as Gondwana fully collided with Laurussia in the Carboniferous.<ref name="Cocks-2016" /><ref name="Golonka-2020" /><ref>{{Cite journal |last1=Franke |first1=Wolfgang |last2=Cocks |first2=L. Robin M. |last3=Torsvik |first3=Trond H. |date=2017 |title=The Palaeozoic Variscan oceans revisited |url=https://linkinghub.elsevier.com/retrieve/pii/S1342937X17301399 |journal=Gondwana Research |language=en |volume=48 |pages=257–284 |doi=10.1016/j.gr.2017.03.005|bibcode=2017GondR..48..257F |url-access=subscription }}</ref>