In-geology,-a-supercontinent-is-the-assembly-of-most-or-all-of-Earth's-continental-blocks-or-cratons-to-form-a-single-large-landmass.^[1][2][3]-However,-some-earth-scientists-use-a-different-definition,-"a-grouping-of-formerly-dispersed-continents",-which-leaves-room-for-interpretation-and-is-easier-to-apply-to-Precambrian-times^[4]-although-at-least-about-75%-of-the-continental-crust-then-in-existence-has-been-proposed-as-a-limit-to-separate-supercontinents-from-other-groupings.^[5]

Supercontinents-have-assembled-and-dispersed-multiple-times-in-the-geologic-past-(see-table).-According-to-modern-definitions,-a-supercontinent-does-not-exist-today;^[1]-the-closest-in-existence-to-a-supercontinent-is-the-current-Afro-Eurasian-landmass,-which-covers-approx.-57%-of-Earth's-total-land-area.-The-supercontinent-Pangaea-is-the-collective-name-describing-all-of-the-continental-landmasses-when-they-were-most-recently-near-to-one-another.-The-positions-of-continents-have-been-accurately-determined-back-to-the-early-Jurassic,-shortly-before-the-breakup-of-Pangaea-(see-animated-image).^[6]-The-earlier-continent-Gondwana-is-not-considered-a-supercontinent-under-the-first-definition-since-the-landmasses-of-Baltica,-Laurentia-and-Siberia-were-separate-at-the-time.^[7]

The-following-table-names-reconstructed-ancient-supercontinents,-using-Bradley's-2011-looser-definition,^[7]-with-an-approximate-timescale-of-millions-of-years-ago-(Ma).

There-are-two-contrasting-models-for-supercontinent-evolution-through-geological-time.-The-first-model-theorizes-that-at-least-two-separate-supercontinents-existed-comprising-Vaalbara-(from-~3636-to-2803 Ma)-and-Kenorland-(from-~2720-to-2450 Ma).-The-Neoarchean-supercontinent-consisted-of-Superia-and-Sclavia.-These-parts-of-Neoarchean-age-broke-off-at-~2480-and-2312 Ma-and-portions-of-them-later-collided-to-form-Nuna-(Northern-Europe-North-America)-(~1820 Ma).-Nuna-continued-to-develop-during-the-Mesoproterozoic,-primarily-by-lateral-accretion-of-juvenile-arcs,-and-in-~1000 Ma-Nuna-collided-with-other-land-masses,-forming-Rodinia.^[4]-Between-~825-and-750 Ma-Rodinia-broke-apart.^[12]-However,-before-completely-breaking-up,-some-fragments-of-Rodinia-had-already-come-together-to-form-Gondwana-(also-known-as-Gondwanaland)-by-~608 Ma.-Pangaea-formed-by-~336 Ma-through-the-collision-of-Gondwana,-Laurasia-(Laurentia-and-Baltica),-and-Siberia.

The-second-model-(Kenorland-Arctica)-is-based-on-both-palaeomagnetic-and-geological-evidence-and-proposes-that-the-continental-crust-comprised-a-single-supercontinent-from-~2.72 Ga-until-break-up-during-the-Ediacaran-Period-after-~0.573 Ga.-The-reconstruction^[13]-is-derived-from-the-observation-that-palaeomagnetic-poles-converge-to-quasi-static-positions-for-long-intervals-between-~2.72–2.115,-1.35–1.13,-and-0.75–0.573 Ga-with-only-small-peripheral-modifications-to-the-reconstruction.^[14]-During-the-intervening-periods,-the-poles-conform-to-a-unified-apparent-polar-wander-path.-Although-it-contrasts-the--first-model,-the-first-phase-(Protopangea)-essentially-incorporates-Vaalbara-and-Kenorland-of-the-first-model.-The-explanation-for-the-prolonged-duration-of-the-Protopangea-Paleopangea-supercontinent-appears-to-be-that-lid-tectonics-(comparable-to-the-tectonics-operating-on-Mars-and-Venus)-prevailed-during-Precambrian-times.-According-to-this-theory,-Plate-tectonics-as-seen-on-the-contemporary-Earth-became-dominant-only-during-the-latter-part-of-geological-times.^[14]-This-approach-was-widely-criticized-by-many-researchers-as-it-uses-incorrect-application-of-paleomagnetic-data.^[15]

The-Phanerozoic-supercontinent-Pangaea-began-to-break-up-215 Ma-and-is-still-doing-so-today.-Because-Pangaea-is-the-most-recent-of-Earth's-supercontinents,-it-is-the-most-well-known-and-understood.-Contributing-to-Pangaea's-popularity-in-the-classroom-is-the-fact-that-its-reconstruction-is-almost-as-simple-as-fitting-the-present-continents-bordering-the-Atlantic-type-oceans-like-puzzle-pieces.^[4]

A-supercontinent-cycle-is-the-break-up-of-one-supercontinent-and-the-development-of-another,-which-takes-place-on-a-global-scale.^[4]-Supercontinent-cycles-are-not-the-same-as-the-Wilson-cycle,-which-is-the-opening-and-closing-of-an-individual-oceanic-basin.-The-Wilson-cycle-rarely-synchronizes-with-the-timing-of-a-supercontinent-cycle.^[1]-However,-supercontinent-cycles-and-Wilson-cycles-were-both-involved-in-the-creation-of-Pangaea-and-Rodinia.^[6]

Secular-trends-such-as-carbonatites,-granulites,-eclogites,-and-greenstone-belt-deformation-events-are-all-possible-indicators-of-Precambrian-supercontinent-cyclicity,-although-the-Protopangea-Paleopangea-solution-implies-that-Phanerozoic-style-of-supercontinent-cycles-did-not-operate-during-these-times.-Also,-there-are-instances-where-these-secular-trends-have-a-weak,-uneven,-or-absent-imprint-on-the-supercontinent-cycle;-secular-methods-for-supercontinent-reconstruction-will-produce-results-that-have-only-one-explanation,-and-each-explanation-for-a-trend-must-fit-in-with-the-rest.^[4]

The-causes-of-supercontinent-assembly-and-dispersal-are-thought-to-be-driven-by-convection-processes-in-Earth's-mantle.-Approximately-660 km-into-the-mantle,-a-discontinuity-occurs,-affecting-the-surface-crust-through-processes-like-plumes-and-superplumes-(aka-large-low-shear-velocity-provinces).-When-a-slab-of-the-subducted-crust-is-denser-than-the-surrounding-mantle,-it-sinks-to-discontinuity.-Once-the-slabs-build-up,-they-will-sink-through-to-the-lower-mantle-in-what-is-known-as-a-"slab-avalanche".-This-displacement-at-the-discontinuity-will-cause-the-lower-mantle-to-compensate-and-rise-elsewhere.-The-rising-mantle-can-form-a-plume-or-superplume.^[1]

Besides-having-compositional-effects-on-the-upper-mantle-by-replenishing-the-large-ion-lithophile-elements,-volcanism-affects-plate-movement.^[1]-The-plates-will-be-moved-towards-a-geoidal-low-perhaps-where-the-slab-avalanche-occurred-and-pushed-away-from-the-geoidal-high-that-can-be-caused-by-the-plumes-or-superplumes.-This-causes-the-continents-to-push-together-to-form-supercontinents-and-was-evidently-the-process-that-operated-to-cause-the-early-continental-crust-to-aggregate-into-Protopangea.^[16]-Dispersal-of-supercontinents-is-caused-by-the-accumulation-of-heat-underneath-the-crust-due-to-the-rising-of-very-large-convection-cells-or-plumes,-and-a-massive-heat-release-resulted-in-the-final-break-up-of-Paleopangea.^[17]-Accretion-occurs-over-geoidal-lows-that-can-be-caused-by-avalanche-slabs-or-the-downgoing-limbs-of-convection-cells.-Evidence-of-the-accretion-and-dispersion-of-supercontinents-is-seen-in-the-geological-rock-record.

The-influence-of-known-volcanic-eruptions-does-not-compare-to-that-of-flood-basalts.-The-timing-of-flood-basalts-has-corresponded-with-a-large-scale-continental-break-up.-However,-due-to-a-lack-of-data-on-the-time-required-to-produce-flood-basalts,-the-climatic-impact-is-difficult-to-quantify.-The-timing-of-a-single-lava-flow-is-also-undetermined.-These-are-important-factors-on-how-flood-basalts-influenced-paleoclimate.^[6]

Global-paleogeography-and-plate-interactions-as-far-back-as-Pangaea-are-relatively-well-understood-today.-However,-the-evidence-becomes-more-sparse-further-back-in-geologic-history.-Marine-magnetic-anomalies,-passive-margin-match-ups,-geologic-interpretation-of-orogenic-belts,-paleomagnetism,-paleobiogeography-of-fossils,-and-distribution-of-climatically-sensitive-strata-are-all-methods-to-obtain-evidence-for-continent-locality-and-indicators-of-the-environment-throughout-time.^[4]

Phanerozoic-(541-Ma-to-present)-and-Precambrian-(4.6 Ga-to-541 Ma)-had-primarily-passive-margins-and-detrital-zircons-(and-orogenic-granites),-whereas-the-tenure-of-Pangaea-contained-few.^[4]-Matching-edges-of-continents-are-where-passive-margins-form.-The-edges-of-these-continents-may-rift.-At-this-point,-seafloor-spreading-becomes-the-driving-force.-Passive-margins-are-therefore-born-during-the-break-up-of-supercontinents-and-die-during-supercontinent-assembly.-Pangaea's-supercontinent-cycle-is-a-good-example-of-the-efficiency-of-using-the-presence-or-lack-of,-these-entities-to-record-the-development,-tenure,-and-break-up-of-supercontinents.-There-is-a-sharp-decrease-in-passive-margins-between-500-and-350 Ma-during-the-timing-of-Pangaea's-assembly.-The-tenure-of-Pangaea-is-marked-by-a-low-number-of-passive-margins-during-336-to-275 Ma,-and-its-break-up-is-indicated-accurately-by-an-increase-in-passive-margins.^[4]

Orogenic-belts-can-form-during-the-assembly-of-continents-and-supercontinents.-The-orogenic-belts-present-on-continental-blocks-are-classified-into-three-different-categories-and-have-implications-for-interpreting-geologic-bodies.^[1]-Intercratonic-orogenic-belts-are-characteristic-of-ocean-basin-closure.-Clear-indicators-of-intracratonic-activity-contain-ophiolites-and-other-oceanic-materials-that-are-present-in-the-suture-zone.-Intracratonic-orogenic-belts-occur-as-thrust-belts-and-do-not-contain-any-oceanic-material.-However,-the-absence-of-ophiolites-is-not-strong-evidence-for-intracratonic-belts,-because-the-oceanic-material-can-be-squeezed-out-and-eroded-away-in-an-intracratonic-environment.-The-third-kind-of-orogenic-belt-is-a-confined-orogenic-belt-which-is-the-closure-of-small-basins.-The-assembly-of-a-supercontinent-would-have-to-show-intracratonic-orogenic-belts.^[1]-However,-interpretation-of-orogenic-belts-can-be-difficult.

The-collision-of-Gondwana-and-Laurasia-occurred-in-the-late-Palaeozoic.-By-this-collision,-the-Variscan-mountain-range-was-created,-along-the-equator.^[6]-This-6000-km-long-mountain-range-is-usually-referred-to-in-two-parts:-the-Hercynian-mountain-range-of-the-late-Carboniferous-makes-up-the-eastern-part,-and-the-western-part-is-called-the-Appalachians,-uplifted-in-the-early-Permian.-(The-existence-of-a-flat-elevated-plateau-like-the-Tibetan-Plateau-is-under-much-debate.)-The-locality-of-the-Variscan-range-made-it-influential-to-both-the-northern-and-southern-hemispheres.-The-elevation-of-the-Appalachians-would-greatly-influence-global-atmospheric-circulation.^[6]

Continents-affect-the-climate-of-the-planet-drastically,-with-supercontinents-having-a-larger,-more-prevalent-influence.-Continents-modify-global-wind-patterns,-control-ocean-current-paths,-and-have-a-higher-albedo-than-the-oceans.^[1]-Winds-are-redirected-by-mountains,-and-albedo-differences-cause-shifts-in-onshore-winds.-Higher-elevation-in-continental-interiors-produces-a-cooler,-drier-climate,-the-phenomenon-of-continentality.-This-is-seen-today-in-Eurasia,-and-rock-record-shows-evidence-of-continentality-in-the-middle-of-Pangaea.^[1]

The-term-glacial-epoch-refers-to-a-long-episode-of-glaciation-on-Earth-over-millions-of-years.^[18]-Glaciers-have-major-implications-on-the-climate,-particularly-through-sea-level-change.-Changes-in-the-position-and-elevation-of-the-continents,-the-paleolatitude-and-ocean-circulation-affect-the-glacial-epochs.-There-is-an-association-between-the-rifting-and-breakup-of-continents-and-supercontinents-and-glacial-epochs.^[18]-According-to-the-first-model-for-Precambrian-supercontinents-described-above-the-breakup-of-Kenorland-and-Rodinia-was-associated-with-the-Paleoproterozoic-and-Neoproterozoic-glacial-epochs,-respectively.-In-contrast,-the-second-solution-described-above-shows-that-these-glaciations-correlated-with-periods-of-low-continental-velocity-and-it-is-concluded-that-a-fall-in-tectonic-and-corresponding-volcanic-activity-was-responsible-for-these-intervals-of-global-frigidity.^[14]-During-the-accumulation-of-supercontinents-with-times-of-regional-uplift,-glacial-epochs-seem-to-be-rare-with-little-supporting-evidence.-However,-the-lack-of-evidence-does-not-allow-for-the-conclusion-that-glacial-epochs-are-not-associated-with-the-collisional-assembly-of-supercontinents.^[18]-This-could-just-represent-a-preservation-bias.

During-the-late-Ordovician-(~458.4-Ma),-the-particular-configuration-of-Gondwana-may-have-allowed-for-glaciation-and-high-CO₂-levels-to-occur-at-the-same-time.^[19]-However,-some-geologists-disagree-and-think-that-there-was-a-temperature-increase-at-this-time.-This-increase-may-have-been-strongly-influenced-by-the-movement-of-Gondwana-across-the-South-Pole,-which-may-have-prevented-lengthy-snow-accumulation.-Although-late-Ordovician-temperatures-at-the-South-Pole-may-have-reached-freezing,-there-were-no-ice-sheets-during-the-early-Silurian-(~443.8 Ma)-through-the-late-Mississippian-(~330.9 Ma).^[6]-Agreement-can-be-met-with-the-theory-that-continental-snow-can-occur-when-the-edge-of-a-continent-is-near-the-pole.-Therefore,-Gondwana,-although-located-tangent-to-the-South-Pole,-may-have-experienced-glaciation-along-its-coast.^[19]

Though-precipitation-rates-during-monsoonal-circulations-are-difficult-to-predict,-there-is-evidence-for-a-large-orographic-barrier-within-the-interior-of-Pangaea-during-the-late-Paleozoic-(~251.902 Ma).-The-possibility-of-the-SW-NE-trending-Appalachian-Hercynian-Mountains-makes-the-region's-monsoonal-circulations-potentially-relatable-to-present-day-monsoonal-circulations-surrounding-the-Tibetan-Plateau,-which-is-known-to-positively-influence-the-magnitude-of-monsoonal-periods-within-Eurasia.-It-is-therefore-somewhat-expected-that-lower-topography-in-other-regions-of-the-supercontinent-during-the-Jurassic-would-negatively-influence-precipitation-variations.-The-breakup-of-supercontinents-may-have-affected-local-precipitation.^[20]-When-any-supercontinent-breaks-up,-there-will-be-an-increase-in-precipitation-runoff-over-the-surface-of-the-continental-landmasses,-increasing-silicate-weathering-and-the-consumption-of-CO₂.^[12]

Even-though-during-the-Archaean-solar-radiation-was-reduced-by-30-percent-and-the-Cambrian-Precambrian-boundary-by-six-percent,-the-Earth-has-only-experienced-three-ice-ages-throughout-the-Precambrian.^[6]-Erroneous-conclusions-are-more-likely-to-be-made-when-models-are-limited-to-one-climatic-configuration-(which-is-usually-present-day).^[21]

Cold-winters-in-continental-interiors-are-due-to-rate-ratios-of-radiative-cooling-(greater)-and-heat-transport-from-continental-rims.-To-raise-winter-temperatures-within-continental-interiors,-the-rate-of-heat-transport-must-increase-to-become-greater-than-the-rate-of-radiative-cooling.-Through-climate-models,-alterations-in-atmospheric-CO₂-content-and-ocean-heat-transport-are-not-comparatively-effective.^[21]

CO₂-models-suggest-that-values-were-low-in-the-late-Cenozoic-and-Carboniferous-Permian-glaciations.-Although-early-Paleozoic-values-are-much-larger-(more-than-ten-percent-higher-than-that-of-today).-This-may-be-due-to-high-seafloor-spreading-rates-after-the-breakup-of-Precambrian-supercontinents-and-the-lack-of-land-plants-as-a-carbon-sink.^[19]

During-the-late-Permian,-it-is-expected-that-seasonal-Pangaean-temperatures-varied-drastically.-Subtropic-summer-temperatures-were-warmer-than-that-of-today-by-as-much-as-6–10-degrees-and-mid-latitudes-in-the-winter-were-less-than-−30-degrees-Celsius.-These-seasonal-changes-within-the-supercontinent-were-influenced-by-the-large-size-of-Pangaea.-And,-just-like-today,-coastal-regions-experienced-much-less-variation.^[6]

During-the-Jurassic,-summer-temperatures-did-not-rise-above-zero-degrees-Celsius-along-the-northern-rim-of-Laurasia,-which-was-the-northernmost-part-of-Pangaea-(the-southernmost-portion-of-Pangaea-was-Gondwana).-Ice-rafted-dropstones-sourced-from-Russia-are-indicators-of-this-northern-boundary.-The-Jurassic-is-thought-to-have-been-approximately-10-degrees-Celsius-warmer-along-90-degrees-East-paleolongitude-compared-to-the-present-temperature-of-today's-central-Eurasia.^[21]

Many-studies-of-the-Milankovitch-fluctuations-during-supercontinent-time-periods-have-focused-on-the-Mid-Cretaceous.-Present-amplitudes-of-Milankovitch-cycles-over-present-day-Eurasia-may-be-mirrored-in-both-the-southern-and-northern-hemispheres-of-the-supercontinent-Pangaea.-Climate-modeling-shows-that-summer-fluctuations-varied-14–16-degrees-Celsius-on-Pangaea,-which-is-similar-or-slightly-higher-than-summer-temperatures-of-Eurasia-during-the-Pleistocene.-The-largest-amplitude-Milankovitch-cycles-are-expected-to-have-been-at-mid-to-high-latitudes-during-the-Triassic-and-Jurassic.^[21]

Granites-and-detrital-zircons-have-notably-similar-and-episodic-appearances-in-the-rock-record.-Their-fluctuations-correlate-with-Precambrian-supercontinent-cycles.-The-U–Pb-zircon-dates-from-orogenic-granites-are-among-the-most-reliable-aging-determinants.-Some-issues-exist-with-relying-on-granite-sourced-zircons,-such-as-a-lack-of-evenly-globally-sourced-data-and-the-loss-of-granite-zircons-by-sedimentary-coverage-or-plutonic-consumption.-Where-granite-zircons-are-less-adequate,-detrital-zircons-from-sandstones-appear-and-make-up-for-the-gaps.-These-detrital-zircons-are-taken-from-the-sands-of-major-modern-rivers-and-their-drainage-basins.^[4]-Oceanic-magnetic-anomalies-and-paleomagnetic-data-are-the-primary-resources-used-for-reconstructing-continent-and-supercontinent-locations-back-to-roughly-150-Ma.^[6]

Plate-tectonics-and-the-chemical-composition-of-the-atmosphere-(specifically-greenhouse-gases)-are-the-two-most-prevailing-factors-present-within-the-geologic-time-scale.-Continental-drift-influences-both-cold-and-warm-climatic-episodes.-Atmospheric-circulation-and-climate-are-strongly-influenced-by-the-location-and-formation-of-continents-and-mega-continents.-Therefore,-continental-drift-influences-mean-global-temperature.^[6]

Oxygen-levels-of-the-Archaean-Eon-were-negligible-and-today-they-are-roughly-21-percent.-It-is-thought-that-the-Earth's-oxygen-content-has-risen-in-stages:-six-or-seven-steps-that-are-timed-very-closely-to-the-development-of-Earth's-supercontinents.^[22]

1. Continents-collide
2. Supermountains-form
3. Erosion-of-super-mountains
4. Large-quantities-of-minerals-and-nutrients-wash-out-to-open-ocean
5. Explosion-of-marine-algae-life-(partly-sourced-from-noted-nutrients)
6. Mass-amounts-of-oxygen-produced-during-photosynthesis

The-process-of-Earth's-increase-in-atmospheric-oxygen-content-is-theorized-to-have-started-with-the-continent-continent-collision-of-huge-landmasses-forming-supercontinents,-and-therefore-possibly-supercontinent-mountain-ranges-(super-mountains).-These-super-mountains-would-have-eroded,-and-the-mass-amounts-of-nutrients,-including-iron-and-phosphorus,-would-have-washed-into-oceans,-just-as-we-see-happening-today.-The-oceans-would-then-be-rich-in-nutrients-essential-to-photosynthetic-organisms,-which-would-then-be-able-to-respire-mass-amounts-of-oxygen.-There-is-an-apparent-direct-relationship-between-orogeny-and-the-atmospheric-oxygen-content.-There-is-also-evidence-for-increased-sedimentation-concurrent-with-the-timing-of-these-mass-oxygenation-events,-meaning-that-the-organic-carbon-and-pyrite-at-these-times-were-more-likely-to-be-buried-beneath-sediment-and-therefore-unable-to-react-with-the-free-oxygen.-This-sustained-the-atmospheric-oxygen-increases.^[22]

During-this-time,-2.65 Ga-there-was-an-increase-in-molybdenum-isotope-fractionation.-It-was-temporary-but-supports-the-increase-in-atmospheric-oxygen-because-molybdenum-isotopes-require-free-oxygen-to-fractionate.-Between-2.45-and-2.32 Ga,-the-second-period-of-oxygenation-occurred,-it-has-been-called-the-'great-oxygenation-event.'-Many-pieces-of-evidence-support-the-existence-of-this-event,-including-red-beds-appearance-2.3 Ga-(meaning-that-Fe³⁺-was-being-produced-and-became-an-important-component-in-soils).-The-third-oxygenation-stage-approximately-1.8 Ga-is-indicated-by-the-disappearance-of-iron-formations.-Neodymium-isotopic-studies-suggest-that-iron-formations-are-usually-from-continental-sources,-meaning-that-dissolved-Fe-and-Fe²⁺-had-to-be-transported-during-continental-erosion.-A-rise-in-atmospheric-oxygen-prevents-Fe-transport,-so-the-lack-of-iron-formations-may-have-been-due-to-an-increase-in-oxygen.-The-fourth-oxygenation-event,-roughly-0.6 Ga,-is-based-on-modeled-rates-of-sulfur-isotopes-from-marine-carbonate-associated-sulfates.-An-increase-(near-doubled-concentration)-of-sulfur-isotopes,-which-is-suggested-by-these-models,-would-require-an-increase-in-the-oxygen-content-of-the-deep-oceans.-Between-650-and-550 Ma-there-were-three-increases-in-ocean-oxygen-levels,-this-period-is-the-fifth-oxygenation-stage.-One-of-the-reasons-indicating-this-period-to-be-an-oxygenation-event-is-the-increase-in-redox-sensitive-molybdenum-in-black-shales.-The-sixth-event-occurred-between-360-and-260 Ma-and-was-identified-by-models-suggesting-shifts-in-the-balance-of-³⁴S-in-sulfates-and-¹³C-in-carbonates,-which-were-strongly-influenced-by-an-increase-in-atmospheric-oxygen.^[22][23]

• List-of-paleocontinents
• Superocean