Rodinia

Rodinia

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In geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, Rodinia (from the Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

 "Родить", rodit, meaning "to give birth") is the name of a supercontinent
Supercontinent
In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...

, a continent which contained most or all of Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's landmass. According to plate tectonic reconstructions
Plate reconstruction
Plate reconstruction is the process of reconstructing the positions of tectonic plates relative to each other or to other reference frames, such as the earth's magnetic field or groups of hotspots, in the geological past...

, Rodinia existed between 1.1 billion and 750 million years ago, in the Neoproterozoic
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1,000 to 542.0 ± 1.0 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods...

 era. It formed at ~1.0 Ga by accretion and collision of fragments produced by breakup of the older supercontinent, Columbia
Columbia (supercontinent)
Columbia, also known as Nuna and Hudsonland, was one of Earth's oldest supercontinents. It was first proposed by J.J.W. Rogers and M. Santosh and is thought to have existed approximately 1.8 to 1.5 billion years ago in the Paleoproterozoic Era. Zhao et al...

, which was assembled by global-scale 2.0-1.8 Ga collisional events.

Rodinia broke up in the Neoproterozoic and its continental fragments were re-assembled to form another supercontinent, called Pangaea
Pangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....

 300-250 million years ago. In contrast with Pangaea, little is known yet about the exact configuration and geodynamic
Geodynamics
Geodynamics is a subfield of geophysics dealing with dynamics of the Earth. It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading, mountain building, volcanoes, earthquakes, faulting and...

 history of Rodinia. Paleomagnetic evidence
Paleomagnetism
Paleomagnetism is the study of the record of the Earth's magnetic field in rocks. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form. This record provides information on the past behavior of Earth's magnetic field and the past location of...

 provides some clues to the paleolatitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 of individual pieces of the Earth's crust, but not to their longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

, which geologists have pieced together by comparing similar geologic features, often now widely dispersed.

The extreme cooling of the global climate around 700 million years ago (the so called Snowball Earth
Snowball Earth
The Snowball Earth hypothesis posits that the Earth's surface became entirely or nearly entirely frozen at least once, some time earlier than 650 Ma . Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical...

 of the Cryogenian
Cryogenian
The Cryogenian is a geologic period that lasted from . It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran...

 period) and the rapid evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 of primitive life during the subsequent Ediacaran
Ediacaran
The Ediacaran Period , named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon...

 and Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 periods are often thought to have been triggered by the breaking up of Rodinia.

Paleogeographic reconstructions


The idea that a supercontinent existed in the early Neoproterozoic arose in the 1970s
1970s
File:1970s decade montage.png|From left, clockwise: US President Richard Nixon doing the V for Victory sign after his resignation from office after the Watergate scandal in 1974; Refugees aboard a US naval boat after the Fall of Saigon, leading to the end of the Vietnam War in 1975; The 1973 oil...

, when geologists mentioned that orogens of this age exist on virtually all craton
Craton
A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...

s. Examples are the Grenville orogeny
Grenville orogeny
The Grenville Orogeny was a long-lived Mesoproterozoic mountain-building event associated with the assembly of the supercontinent Rodinia. Its record is a prominent orogenic belt which spans a significant portion of the North American continent, from Labrador to Mexico, as well as to Scotland...

 in North America, the Uralian orogeny
Uralian orogeny
The Uralian orogeny refers to the long series of mountain building events that raised the Ural Mountains, starting in the Late Carboniferous and Permian periods of the Palaeozoic Era, ca. 318-299 and 299-251 Mya, and ending with the last series of continental collisions in Triassic to early...

 in Siberia and the Dalslandian orogeny in Europe.

Since then many alternative reconstructions have been proposed for the configuration of the cratons in this supercontinent. Most of these reconstructions are based on the correlation of the orogens on different cratons. Though the configuration of the core cratons in Rodinia is now reasonably well known, recent reconstructions still differ in many details. Geologists try to decrease the uncertainties by collecting geological and paleomagnetical data.

Rodinia's landmass was probably centered south of the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

. Most reconstructions show Rodinia's core was formed by the North American craton (the later paleocontinent of Laurentia
Laurentia
Laurentia is a large area of continental craton, which forms the ancient geological core of the North American continent...

), surrounded in the southeast with the East European craton
East European craton
The East European craton is the core of the Baltica proto-plate and consists of three crustal regions/segments: Fennoscandia to the northwest, Volgo-Uralia to the east, and Sarmatia to the south...

 (the later paleocontinent of Baltica
Baltica
Baltica is a name applied by geologists to a late-Proterozoic, early-Palaeozoic continent that now includes the East European craton of northwestern Eurasia. Baltica was created as an entity not earlier than 1.8 billion years ago. Before this time, the three segments/continents that now comprise...

), the Amazonian craton ("Amazonia") and the West African craton
West African craton
The West African craton is one of the five large masses, or cratons, of the Precambrian basement rock of Africa that make up the African Plate, the others being the Kalahari craton, Congo craton, Saharan Metacraton and Tanzania craton. These land masses came together in the late Precambrian and...

; in the south with the Rio de la Plata
Rio de la Plata Craton
The Río de la Plata craton is one of the five cratons of the South American continent. The other four cratons are: Amazonian, São Francisco, Río Apa and Arequipa–Antofalla.It crops out in southern Uruguay and parts of Argentina...

 and São Francisco craton
Sao Francisco craton
The São Francisco craton is located in the eastern part of South America. Outcrops in the Brazilian states of Minas Gerais and Bahia.It includes a number of different blocks of the Archean basement, separated by orogenic belts. The belts are characterized by sediment basins and passive continental...

s; in the southwest with the Congo
Congo craton
The Congo craton, covered by the Palaeozoic-to-recent Congo basin, is an ancient Precambrian craton that with four others makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time...

 and Kalahari craton
Kalahari craton
The Kalahari craton is a craton, an old and stable part of the continental lithosphere with thick crust and deep lithospheric roots extending up to a few hundred kilometers into the Earth's mantle, that occupies a large portion of South Africa and consists of the Kaapvaal, the Zimbabwe craton, the...

s; and in the northeast with Australia
Australia (continent)
Australia is the world's smallest continent, comprising the mainland of Australia and proximate islands including Tasmania, New Guinea, the Aru Islands and Raja Ampat Islands...

, India
Indian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...

 and eastern Antarctica. The positions of Siberia
Siberia (continent)
Siberia is the craton located in the heart of the region of Siberia. Siberia or "Angaraland" is today the Central Siberian Plateau...

 and North
North China craton
The North China Craton is one of the smaller continental cratons of the Earth. It covers a total area of around 1.7 million square kilometres in the northeast of China, most of Korea and the southern part of Mongolia, and has a shape quite akin to a funnel, with a long east-west axis in the...

 and South China
South China (continent)
South China continent, also known as South China craton, South Chinese craton, or Yangtze craton, was an ancient continent that contained today's South and Southeast China , Indochina, and parts of Southeast Asia...

 north of the North American craton differ strongly depending on the reconstruction:
  • SWEAT-Configuration (Southwest US-East Antarctica craton): Antarctica is on the Southwest of Laurentia and Australia is at the North of Antarctica.
  • AUSWUS-Configuration (Australia-western US): Australia is at the West of Laurentia.
  • AUSMEX-Configuration (Australia-Mexico): Australia is at the location of nowadays Mexico relative to Laurentia.
  • Bogdanova et al. (2009) based on Li et al. (2008) has South China on the West coast of Laurentia.
  • Siberia attached to the western US (via the Belt Supergroup
    Belt Supergroup
    The Belt Supergroup, is an assemblage of Mesoproterozoic sedimentary rocks which outcrop chiefly in western Montana, but also exposed in Idaho, Washington, Wyoming, and British Columbia. It is most famous as the formation that makes up Glacier National Park in northwest Montana...

    ), as in Sears and Price (2000).
  • Rodinia of Scotese
    Christopher Scotese
    Christopher R. Scotese is geologist at the University of Texas at Arlington. He received his PhD from the University of Chicago in 1985. He is creator of the Paleomap Project, which aims to map Earth over the last billion years, and is credited with predicting Pangaea Ultima, a possible future...

    .

Little is known about the paleogeography before the formation of Rodinia. Paleomagnetic and geologic data is only definite enough to form reconstructions that are generally agreed on from the breakup of Rodinia onwards. Rodinia was probably formed between 1100 and 1000 million years ago and broke up again before 750 million years ago. Rodinia was surrounded by the superocean
Superocean
A superocean is an ocean which surrounds a supercontinent. It is less commonly defined as any ocean larger than the current Pacific Ocean. Named global superoceans include Mirovia, which surrounded the supercontinent Rodinia, and Panthalassa, which surrounded the supercontinent Pangaea...

 geologists are calling Mirovia
Mirovia
Mirovia was a hypothesized superocean which may have been a global ocean surrounding the supercontinent Rodinia in the Neoproterozoic Era, about 1 billion to 750 million years ago. The Mirovia may be essentially identical to, or the precursor of, the hypothesized Pan-African Ocean, which followed...

 (from Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

 мировой, mirovoy, meaning "global"; Родина, rodina, meaning "motherland").

Break up


In contrast to Rodinia's formation, the movements of continental masses during and since its breakup are fairly well understood. Rift
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....

ing did not start everywhere simultaneously. Extensive lava flows and volcanic eruptions of Neoproterozoic age are found on most continents, evidence for large scale rifting about 750 million years ago. As early as 850 and 800 million years ago, a rift developed between the continental masses of present-day Australia, eastern Antarctica, India and the Congo and Kalahari cratons on one side and later Laurentia, Baltica, Amazonia
Amazonian shield
The Amazonian shield is a geologic province located in South America and occupies much of the eastern part of the continent. Smaller areas of Precambrian rocks to the North and South of the Amazonian shield are the Guiana Shield, Rio Apa and Platian cratons, to the West there is the Sao Francisco...

 and the West African and Rio de la Plata cratons on the other. This rift developed into the Adamastor Ocean during the Ediacaran.

The first group of cratons would eventually, around 550 million years ago (on the boundary between the Ediacaran and Cambrian), fuse again with Amazonia, West Africa and the Rio de la Plata craton. This tectonic phase
Tectonic phase
A tectonic phase or deformation phase is in structural geology and petrology a phase in which tectonic movement or metamorphism took place. Tectonic phases can be extensional or compressional in nature....

 is called the Pan-African orogeny
Pan-African orogeny
The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago....

. It created a configuration of continents that would remain stable for hundreds of millions of years in the form of the continent Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

.

In a separate rifting event about 610 million years ago (halfway in the Ediacaran period), the Iapetus Ocean
Iapetus Ocean
The Iapetus Ocean was an ocean that existed in the Neoproterozoic and Paleozoic eras of the geologic timescale . The Iapetus Ocean was situated in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia...

 formed. The eastern part of this ocean formed between Baltica and Laurentia, the western part between Amazonia and Laurentia. Because the exact moments of this separation and the partially contemporaneous Pan-African orogeny are hard to correlate, it might be that all continental mass was again joined in one supercontinent between roughly 600 and 550 million years ago. This hypothetical supercontinent is called Pannotia
Pannotia
Pannotia, first described by Ian W. D. Dalziel in 1997, is a hypothetical supercontinent that existed from the Pan-African orogeny about six hundred million years ago to the end of the Precambrian about five hundred and fifty million years ago. It is also known as the Vendian supercontinent...

.

Influence on paleoclimate and life


Unlike later supercontinents, Rodinia itself was entirely barren. It existed before life colonized dry land, and, since it predated the formation of the ozone layer
Ozone layer
The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone . This layer absorbs 97–99% of the Sun's high frequency ultraviolet light, which is potentially damaging to the life forms on Earth...

, it was too exposed to ultraviolet sunlight for any organism to inhabit it. Nevertheless, its existence did significantly influence the marine life of its time.

In the Cryogenian period the Earth experienced large glaciations, and temperatures were at least as cool as today. Substantial areas of Rodinia may have been covered by glacier
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...

s or the southern polar ice cap
Polar ice cap
A polar ice cap is a high latitude region of a planet or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land; only that it must be a body of...

.

Low temperatures may have been exaggerated during the early stages of continental rifting. Geothermal heating
Geothermal heating
Geothermal heating is the direct use of geothermal energy for heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of geothermal heating in 2004...

 peaks in crust about to be rifted; and since warmer rocks are less dense
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

, the crustal rocks rise up relative to their surroundings. This rising creates areas of higher altitude, where the air is cooler and ice is less likely to melt with changes in season, and it may explain the evidence of abundant glaciation in the Ediacaran
Ediacaran
The Ediacaran Period , named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon...

 period.

The eventual rifting of the continents created new oceans, and seafloor spreading
Seafloor spreading
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....

, which produces warmer, less-dense oceanic lithosphere
Oceanic lithosphere
Oceanic lithosphereOceanic lithosphere is typically about 50-100 km thick , while the continental lithosphere has a range in thickness from about 40 km to perhaps 200 km; the upper ~30 to ~50 km of the typical continental lithosphere is crust...

. Due to its lower density, hot oceanic lithosphere will not lie as deep as old, cool oceanic lithosphere. In periods with relatively large areas of new lithosphere, the ocean floors come up, causing the eustatic sea level to rise. The result was a greater number of shallower seas.

The increased evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

 from the larger water area of the oceans may have increased rainfall, which, in turn, increased the weathering of exposed rock. By inputting data on the ratio of stable isotopes 18O:16O into computer models, it has been shown that in conjunction with quick-weathering of volcanic rock
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...

, this increased rainfall may have reduced greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 levels to below the threshold required to trigger the period of extreme glaciation known as Snowball Earth
Snowball Earth
The Snowball Earth hypothesis posits that the Earth's surface became entirely or nearly entirely frozen at least once, some time earlier than 650 Ma . Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical...

.

Increased volcanic activity also introduced into the marine environment biologically active nutrients, which may have played an important role in the development of the earliest animals.

See also

  • Columbia (supercontinent)
    Columbia (supercontinent)
    Columbia, also known as Nuna and Hudsonland, was one of Earth's oldest supercontinents. It was first proposed by J.J.W. Rogers and M. Santosh and is thought to have existed approximately 1.8 to 1.5 billion years ago in the Paleoproterozoic Era. Zhao et al...

     for one possible reconstruction of an earlier supercontinent
  • Supercontinent cycle
    Supercontinent cycle
    The supercontinent cycle describes the quasi-periodic aggregation and dispersal of Earth's continental crust. There are varying opinions as to whether the amount of continental crust is increasing, decreasing, or staying about the same, but it is agreed that the Earth's crust is constantly being...


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