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63-513: Until roughly 140  million years ago , the Indian plate formed part of the supercontinent , Gondwana , together with modern Africa, Australia, Antarctica, and South America. Gondwana fragmented as these continents drifted apart at different velocities; a process which led to the opening of the Indian Ocean . In the late Cretaceous approximately 100  million years ago , and subsequent to

126-532: A preservation bias . During the late Ordovician (~458.4 Ma), the particular configuration of Gondwana may have allowed for glaciation and high CO 2 levels to occur at the same time. 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

189-504: A limit has been proposed in which a continent must include at least about 75% of the continental crust then in existence in order to qualify as a supercontinent. Moving under the forces of plate tectonics , supercontinents have assembled and dispersed multiple times in the geologic past. According to modern definitions, a supercontinent does not exist today; the closest is the current Afro-Eurasian landmass, which covers approximately 57% of Earth's total land area. The last period in which

252-550: A low number of passive margins during 336 to 275 Ma, and its break-up is indicated accurately by an increase in passive margins. 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. Intercratonic orogenic belts are characteristic of ocean basin closure. Clear indicators of intracratonic activity contain ophiolites and other oceanic materials that are present in

315-534: A result irreconcilable to current theories of plate tectonics and a refutation of the plume-push hypothesis. Pérez-Díaz concludes that the accelerated movement of the Indian plate is an illusion wrought by large errors in geomagnetic reversal timing around the Cretaceous–Paleogene boundary , and that a recalibration of the time scale shows no such acceleration exists. The collision with the Eurasian plate along

378-578: A single lava flow is also undetermined. These are important factors on how flood basalts influenced paleoclimate . Global palaeogeography 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

441-401: 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. Besides having compositional effects on

504-519: A supercontinent would have to show intracratonic orogenic belts. 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. This 6000-km-long mountain range is usually referred to in two parts: the Hercynian mountain range of the late Carboniferous makes up

567-693: Is a tectonic plate that includes most of Eurasia (a landmass consisting of the traditional continents of Asia and Europe ), with the notable exceptions of the Arabian Peninsula , the Indian subcontinent , and the area east of the Chersky Range in eastern Siberia . It also includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge . The western edge

630-514: Is a triple junction plate boundary with the North American plate and Nubian plate at the seismically active Azores triple junction extending northward along the Mid-Atlantic Ridge towards Iceland . Ridges like the Mid-Atlantic ridge form at a divergent plate boundary . They are located deep underwater and very difficult to study. Scientists know less about ocean ridges than they do

693-642: Is almost as simple as fitting together the present continents bordering the Atlantic ocean like puzzle pieces. For the period before Pangaea, there are two contrasting models for supercontinent evolution through geological time . The first model theorizes that at least two separate supercontinents existed comprising Vaalbara and Kenorland , with Kenorland comprising 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 and North America). Nuna continued to develop during

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756-561: Is an association between the rifting and breakup of continents and supercontinents and glacial epochs. According to the model for Precambrian supercontinent series, the breakup of Kenorland and Rodinia was associated with the Paleoproterozoic and Neoproterozoic glacial epochs, respectively. In contrast, the Protopangea–Paleopangea theory shows that these glaciations correlated with periods of low continental velocity, and it

819-498: 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 is derived from the observation that palaeomagnetic poles converge to quasi-static positions for long intervals between ~2.72–2.115 Ga; 1.35–1.13 Ga; and 0.75–0.573 Ga with only small peripheral modifications to

882-448: Is concluded that a fall in tectonic and corresponding volcanic activity was responsible for these intervals of global frigidity. 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. This could just represent

945-534: Is evidence for a large orographic barrier within the interior of Pangaea during the late Paleozoic (~251.9 Ma). The possibility of the southwest–northeast 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

1008-472: Is seen today in Eurasia , and rock record shows evidence of continentality in the middle of Pangaea. The term glacial-epoch refers to a long episode of glaciation on Earth over millions of years. 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

1071-477: 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 S in sulfates and C in carbonates , which were strongly influenced by an increase in atmospheric oxygen. Granites and detrital zircons have notably similar and episodic appearances in

1134-439: Is the opening and closing of an individual oceanic basin . The Wilson cycle rarely synchronizes with the timing of a supercontinent cycle. However, supercontinent cycles and Wilson cycles were both involved in the creation of Pangaea and Rodinia. Secular trends such as carbonatites , granulites , eclogites , and greenstone belt deformation events are all possible indicators of Precambrian supercontinent cyclicity, although

1197-461: 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. When any supercontinent breaks up, there will be an increase in precipitation runoff over the surface of the continental landmasses, increasing silicate weathering and

1260-500: 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. 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

1323-468: 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. Many studies of the Milankovitch cycles 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

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1386-500: The Main Himalayan Thrust . Supercontinent In geology , a supercontinent is the assembly of most or all of Earth 's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leaves room for interpretation and is easier to apply to Precambrian times. To separate supercontinents from other groupings,

1449-523: The Mesoproterozoic , primarily by lateral accretion of juvenile arcs, and in ~1000 Ma Nuna collided with other land masses, forming Rodinia . Between ~825 and 750 Ma Rodinia broke apart. However, before completely breaking up, some fragments of Rodinia had already come together to form Gondwana by ~608 Ma . Pangaea formed through the collision of Gondwana, Laurasia ( Laurentia and Baltica ), and Siberia . The second model (Kenorland-Arctica)

1512-403: The upper mantle by replenishing the large-ion lithophile elements , volcanism affects plate movement. 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

1575-571: The 1783 eruption of Laki and the 2010 eruption of Eyjafjallajökull , are caused by the North American and the Eurasian plates moving apart, which is a result of divergent plate boundary forces. The convergent boundary between the Eurasian plate and the Indian plate formed the Himalayas mountain range. The geodynamics of Central Asia is dominated by the interaction between the Eurasian plate and

1638-552: The Greater Himalayan fragment and India explains the apparent discrepancy between the crustal shortening estimates in the Himalaya and paleomagnetic data from India and Asia. However, the proposed ocean basin was not constrained by paleomagnetic data from the key time interval of ~120 Mya to ~60 Mya. New paleomagnetic results of this critical time interval from southern Tibet do not support this Greater Indian Ocean basin hypothesis and

1701-709: The Indian plate to compress at a rate of four mm (0.16 in) per year. The westerly side of the Indian plate is a transform boundary with the Arabian plate called the Owen Fracture Zone , and a divergent boundary with the African plate called the Central Indian Ridge (CIR). The northerly side of the plate is a convergent boundary with the Eurasian plate forming the Himalaya and Hindu Kush mountains , called

1764-402: 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

1827-481: 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). 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 coasts. Though precipitation rates during monsoonal circulations are difficult to predict, there

1890-399: 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

1953-480: The amount of convergence between India and Asia (~3,600 km or 2,200 mi). These authors propose a continental fragment of northern Gondwana rifted from India, traveled northward, and initiated the "soft collision" between the Greater Himalaya and Asia at ~50 Mya. This was followed by the "hard collision" between India and Asia occurred at ~25 Mya. Subduction of the resulting ocean basin that formed between

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2016-413: The associated dual collision model. In 2007, German geologists suggested the reason the Indian plate moved so quickly is that it is only half as thick (100 km or 62 mi) as the other plates which formerly constituted Gondwana. The mantle plume that once broke up Gondwana might also have melted the lower part of the Indian subcontinent , which allowed it to move both more quickly and farther than

2079-524: The boundary between India and Nepal formed the orogenic belt that created the Tibetan Plateau and the Himalaya Mountains, as sediment bunched up like earth before a plow . The Indian plate is currently moving north-east at five cm (2.0 in) per year, while the Eurasian plate is moving north at only two cm (0.79 in) per year. This is causing the Eurasian plate to deform, and

2142-676: The boundary from the Nansen Ridge through a broad zone of deformation in North Asia to the Sea of Okhotsk then south through Sakhalin Island and Hokkaido to the triple junction in the Japan Trench . But this simple view has been successfully challenged by more recent research. During the 1970s, Japan was thought to be located on the Eurasian plate at a quadruple junction with the North American plate when

2205-400: 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

2268-414: The breakup of Precambrian supercontinents and the lack of land plants as a carbon sink . 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

2331-422: 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. 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

2394-407: The collision occurred between 55 and 50 Mya, the Indian plate would have covered a distance of 3,000 to 2,000 km (1,900–1,200 mi), moving more quickly than any other known plate. In 2012, paleomagnetic data from the Greater Himalaya was used to propose two collisions to reconcile the discrepancy between the amount of crustal shortening in the Himalaya (~1,300 km or 800 mi) and

2457-723: The consumption of CO 2 . Even though during the Archaean solar radiation was reduced by 30 percent and the Cambrian - Precambrian boundary by 6 percent, the Earth has only experienced three ice ages throughout the Precambrian. Erroneous conclusions are more likely to be made when models are limited to one climatic configuration (which is usually present-day). 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,

2520-452: The contemporary Earth became dominant only during the latter part of geological times. This approach was widely criticized by many researchers as it uses incorrect application of paleomagnetic data. A supercontinent cycle is the break-up of one supercontinent and the development of another, which takes place on a global scale. Supercontinent cycles are not the same as the Wilson cycle , which

2583-426: The continental landmasses were near to one another was 336 to 175 million years ago, forming the supercontinent Pangaea . The positions of continents have been accurately determined back to the early Jurassic , shortly before the breakup of Pangaea. Pangaea's predecessor Gondwana is not considered a supercontinent under the first definition since the landmasses of Baltica , Laurentia and Siberia were separate at

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2646-416: The early continental crust to aggregate into Protopangea. 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. Accretion occurs over geoidal lows that can be caused by avalanche slabs or the downgoing limbs of convection cells. Evidence of

2709-571: The eastern boundary of the North American plate was drawn through southern Hokkaido . New research in the 1990s supported that the Okhotsk microplate was independent from the North American plate and a boundary with the Amurian microplate , sometimes described as "a division within the Eurasian plate" with an unknown western boundary. All volcanic eruptions in Iceland, such as the 1973 eruption of Eldfell ,

2772-572: The eastern part, and the western part is the Appalachian Mountains , uplifted in the early Permian . (The existence of a flat elevated plateau like the Tibetan Plateau is under 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. Continents affect

2835-440: The environment throughout time. 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. 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

2898-679: The gaps. These detrital zircons are taken from the sands of major modern rivers and their drainage basins . Oceanic magnetic anomalies and paleomagnetic data are the primary resources used for reconstructing continent and supercontinent locations back to roughly 150 Ma. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Eurasian plate The Eurasian plate

2961-474: The lack of iron formations may have been the result of 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

3024-462: The large size of Pangaea. And, just like today, coastal regions experienced much less variation. 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

3087-433: The mass amounts of nutrients, including iron and phosphorus , would have washed into oceans, just as is seen 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

3150-603: The other parts. The remains of this plume today form the Marion hotspot ( Prince Edward Islands ), the Kerguelen hotspot , and the Réunion hotspots . As India moved north, it is possible the thickness of the Indian plate degenerated further as it passed over the hotspots and magmatic extrusions associated with the Deccan and Rajmahal Traps . The massive amounts of volcanic gases released during

3213-533: The passage of the Indian plate over the hotspots have been theorised to have played a role in the Cretaceous–Paleogene extinction event , generally held to be due to a large asteroid impact . In 2020, however, geologists at the University of Oxford and the Alfred Wegener Institute found that new plate-motion models displayed increased movement speeds in all mid-ocean ridges during the late Cretaceous,

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3276-739: The planets of the solar system. There is another triple junction where the Eurasian plate meets the Anatolian sub-plate and the Arabian plate . The Anatolian sub-plate is currently being squeezed by the collision of the Eurasian plate with the Arabian plate in the East Anatolian Fault Zone . The boundary between the North American plate and the Eurasian plate in the area around Japan has been described as "shifty". There are different maps for it based on recent tectonics, seismicity and earthquake focal mechanism . The simplest plate geometry draws

3339-479: The rate of heat transport must increase to become greater than the rate of radiative cooling. Through climate models, alterations in atmospheric CO 2 content and ocean heat transport are not comparatively effective. CO 2 models suggest that values were low in the late Cenozoic and Carboniferous-Permian glaciations. Although early Paleozoic values are much larger (more than 10 percent higher than that of today). This may be due to high seafloor spreading rates after

3402-527: The reconstruction. 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

3465-553: The rest. The following table names reconstructed ancient supercontinents, using Bradley's 2011 looser definition, with an approximate timescale of millions of years ago (Ma). 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 involving plumes and superplumes (aka large low-shear-velocity provinces ). When

3528-471: 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

3591-591: The second period of oxygenation occurred, which has been called the 'great oxygenation event.' Evidence supporting this event includes red beds appearance 2.3 Ga (meaning that Fe 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 Fe had to be transported during continental erosion. A rise in atmospheric oxygen prevents Fe transport, so

3654-566: The splitting from Gondwana of conjoined Madagascar and India , the Indian plate split from Madagascar and formed Insular India . It began moving north, at about 20 cm (7.9 in) per year, and is believed to have begun colliding with Asia as early as 55  million years ago , in the Eocene epoch of the Cenozoic . However, some authors suggest the collision between India and Eurasia occurred much later, around 35  million years ago . If

3717-550: 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. Plate tectonics and the chemical composition of the atmosphere (specifically greenhouse gases ) are

3780-403: 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

3843-404: The time. A future supercontinent, termed Pangaea Proxima , is hypothesized to form within the next 250 million years. The Phanerozoic supercontinent Pangaea began to break up 215 Ma and this distancing continues today. Because Pangaea is the most recent of Earth's supercontinents, it is the best known and understood. Contributing to Pangaea's popularity in the classroom, its reconstruction

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3906-485: 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. At 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,

3969-422: 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 supercontinents. Therefore, continental drift influences mean global temperature. Oxygen levels of the Archaean were negligible, and today they are roughly 21 percent. It

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