Rodinia

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One of several discussed reconstructions of Rodinia.

Rodinia is a hypothetical supercontinent of the Proterozoic . It is said to have been formed 1.1 billion years ago and initially broken into two large fragments around 800 million years ago. Rodinia was surrounded by a single ocean, Mirovia .

The name comes from the Russian word родина for "homeland" or "родить" for "to give birth", because the cores of all later continents were united in Rodinia . It was coined in 1990 by Mark McMenamin and Dianna Schulte McMenamin .

The existence of a supercontinent in the Neoproterozoic is no longer disputed in research. However, there are two fundamentally different concepts, the Rodinia concept and the Palaeopangea concept by John D. Piper . The Rodinia concept is currently favored in the literature. The position of the continents within Rodinia and the chronology are still controversial.

Arrangement of the land masses

The model of a supercontinent Rodinia is based on a continent configuration in which Laurentia formed the center around which the other continents were grouped. On the other hand, the Palaeopangea model by John D. Piper, which is based on the Pangea- like arrangement of the continents, is completely different . In the meantime, the Rodinia model has also differentiated itself into several variants, which are referred to in the literature as SWEAT, AUSWUS and AUSMEX.

The SWEAT variant (of S outh w est US - Ea st at t arctica) assumes that Antarctica southwest of Laurentia joined. Australia was adjacent to Antarctica to the north.

The AUSWUS variant (of from tralia - w estern US ), however, believes that Australia was at that time on the western edge of Laurentia. Antarctica was in the same position on Australia as in the SWEAT variant, but had no direct contact with Laurentia due to Australia's further southern position.

In the AUSMEX variant (of from tralia - Mex ico) is Australia further south of Laurentia (relative to the current situation in North America) and closed at about the level of Mexico at Laurentia on.

Bogdanova et al. (2009) based on Li et al. (2008) rejects all three variants. Both works are based on a Rodinia configuration with southern China on the west coast of Laurentia. Parts of South America adjoined the east coast of Laurentia, with Baltica to the north . To the south of Laurentia lay various blocks of the later Gondwana , to the north of Laurentia lay Greenland and Siberia. The positions relate roughly to the orientation of today's North America. In contrast, Goodge et al. (2008) used the SWEAT model again. There is still a long way to go before research can come up with a consistent model of a supercontinent, Rodinia.

Rodinia as a geological continent

One of the several possible continent arrangements 550 million years ago - Rodinia has already disintegrated.

Rodinia was formed through plate tectonic and orogenetic processes in the period between 1300 and 900 million years, mainly through the large-scale Grenville orogeny 1250 to 980 million years ago, on the western and southern edge of Laurentia and North America from the Labrador Peninsula to Mexico and the north - Scotland and Baltica .

In Western Europe , the Dalslandian Orogeny or Svekonorwegian orogeny developed between 1140 and 960 million years ago in the areas of southern Sweden and southern Norway. It correlates with the Grenville orogeny.

In Africa, the Kibaran orogeny, 1.4 to 1 billion years ago, took place in the Congo basin and in the Namaqua-Natal belt of South Africa, the Usagara-Ubendian orogeny and the Irumid orogeny in Malawi and Zambia .

Other orogenes formed in Antarctica , the Indian subcontinent and Australia as well as South America (Amazonia).

Continental fragments of the collapsed hypothetical supercontinent of Columbia were involved .

About 900 million years ago, all of the continental blocks that existed at that time were probably united into a supercontinent. Rodinia persisted as a supercontinent for about 150 million years before breaking up into two large blocks (Northern Rodinia and Southern Rodinia). Continental rifting was widespread between 825 and 740 million years ago . The cause was probably a superplume under Rodinia, which episodic plume events around 825, 780 and 750 million years ago suggest. In the Upper Precambrian (650–550 million years ago) the three neoproterozoic continents Northern Rodinia, Southern Rodinia and the Congo Craton collided during the Cadomian Orogeny and formed the second Neoproterozoic supercontinent, Pannotia ("Greater Gondwana").

On the basis of paleomagnetic data , petrological age determinations and geological correlations of rocks , orrogens , continental drifts , rift formations and mantle plumes , the following synthesis of the formation, configuration and decay of Rodinia was established.

Rodinia forms

By 1100 mya the continents Laurentia , Siberia , the cratons of North China, Cathaysia (part of today's South China) and probably Rio de la Plata were already united to one landmass, while the Yangtze Craton began with the north-west side of Laurentia to collide. These cratons were located in northern temperate latitudes. All other continental blocks (Greater India ( India with NE Madagascar , Sri Lanka and the Seychelles ), West Africa, Amazonia (Amazon shield), Kalahari, Congo-São Francisco with the Sahara metacraton and the Tarim block) were still from Laurentia separated. With the exception of Greater India, which was grouped in high northern latitudes, the rest to the west of Laurentia were between higher northern and southern zones.

About 1050 mya, the Kalahari craton collided with Laurentia to the west, and the Yangtze craton continued its collision. Laurentia with the merged blocks had moved from north to equatorial latitudes. Greater India, Australia with East Antarctica and the Tarim Bloc were located in mid to higher northern latitudes, while Baltica, West Africa, Amazonia and Congo-São Francisco with the Sahara metacraton were grouped opposite. Except for Baltica, West Africa and Amazonia, which were south of Laurentia, the remaining blocks were west of Laurentia.

Around 1000 mya the cratons Congo-São Francisco had united with the Sahara-Metacraton, West Africa as well as Amazonia and Baltica in the west to south with Laurentia. This configuration was now in low southern latitudes up to the South Pole. The still separate blocks of Greater India, Australia with East Antarctica and the Tarim Block were located in northern subtropical to tropical zones.

About 900 my ago, with the collision of Greater India, Australia with East Antarctica and the Tarim Block on the north-west side of Laurentia, almost all of the larger continental blocks that existed at that time were combined into one supercontinent. The Arabic-Nubian shield developed in the area of ​​the Sahara metacraton. Rodinia grouped itself mainly south of the equator to the south pole.

Although Rodinia’s existence is undisputed, there are several models of its continental configuration and geographic location. Most of the reconstructions show the North American craton, later the continent Laurentia, as Rodinia's core. This was surrounded in the southeast by the Eastern European Kraton , the later Baltica. To the south lay the Amazonia (Amazon Shield) and the West Africa craton, while the south-west were the Rio de la Plata and Congo-São Francisco cratons. To the west, the Kraton Kalahari, the Sahara Metacraton and the Arab-Nubian Shield joined. To the north lay Greater India, Australia with East Antarctica and the Tarim Block. The positions of Siberia and of the North China and South China cratons north of the North American craton differ greatly depending on the reconstruction. Rodinia was surrounded by the global ocean Mirovia .

Rodinia disintegrates

Rodinia began to decay through rifting at different points and at different times. Various larger intrusions arose between 870 and 845 mya , which have been detected in South China and Africa as well as in Scandinavia and Scotland. These are seen as the beginning of the decay of Rodinia and signs of Plume events. The supercontinent had meanwhile migrated to low northern areas.

From 825 mya, a superplume developed in northern polar latitudes, which lasted about 25 my, followed by rift breaks in continental areas with various intracontinental intrusions. A plume cluster was presumably formed close to the surface, distributed over larger areas. Australia with East Antarctica, South China, the Tarim Block, Kalahari and the Arab-Nubian Terrane were affected. The supercontinent had meanwhile migrated to the low northern areas and had turned right by about 90 degrees.

Another superplume arose from 780 mya in equatorial latitudes. The land masses of Rodinia were now grouped around the equator. A strong ocean floor spreading to the west separated Greater India and the Arab-Nubian Shield from the rest of the continental masses.

From 750 mya this superplume also caused rifting in the western areas. Australia with East Antarctica, the Tarim Block and the south-western Congo-São Francisco craton with Meta-Sahara were separated. A triple junction (triple point) also generated the splitting off of the southern Chinese kraton.

By 720 mya, a large ocean had formed between Australia with East Antarctica, South China and the northern flank of Laurentia. The Kalahari Kraton and Siberia began to break away from Laurentia. The continental blocks were still grouped around the equator. The Panthalassa Ocean opened while the Mirovia Ocean subducted. Rodinia had largely disintegrated again. Extensive lava flows and volcanic eruptions have been found on most of the continents.

The world climate was in a so-called ice house phase, the Sturtic Ice Age , according to the snowball earth hypothesis .

Between 630 and 550 mya, Amazonia, Siberia, Baltica, Kalahari and Rio de la Plata broke away from Laurentia. Except for North and South China, Australia with East Antarctica, Greater India and the Tarim Block, the remaining continental masses were in low southern latitudes. Laurentia, Siberia and Baltika were opposite the rest of the land configuration.

From around 600 mya, the next supercontinent, Pannotia, began to form from the Rodinia fragments.

literature

  • SV Bogdanova, SA Pisarevsky and ZX Li: Assembly and Breakup of Rodinia (Some Results of IGCP Project 440). Stratigraphy and Geological Correlation, 2009, 17 (3): 259-274, 2009 ISSN  0869-5938
  • JW Goodge, JD Vervoort, CM Fanning, DM Brecke, GL Farmer, IS Williams, PM Myrow, and DJ DePaolo: A positive test of East Antarctica – Laurentia Juxtaposition within the Rodinia supercontinent. Science, 321 (5886): 235-240, New York 2008. ISSN  0036-8075 doi : 10.1126 / science.1159189
  • Volker Kaminske: Location and structure of the supercontinent Rodinia in primeval times . Naturwissenschaftliche Rundschau 61 (12) pp. 634-635 (2009), ISSN  0028-1050
  • Marc AS McMenamin and Dianna L. Schulte McMenamin: The Emergence of Animals - The Cambrian Breakthrough. 217 pp., New York, Columbia University Press, 1990 ISBN 0-231-06646-5 and ISBN 0-231-06647-3
  • John DA Piper: The Neoproterozoic supercontinent: Rodinia or Palaeopangea? Earth and Planetary Science Letters, 176: 131-146, 2000 doi : 10.1016 / S0012-821X (99) 00314-3
  • ZX Li, SV Bogdanova, AS Collins, A. Davidson, B. De Waele, RE Ernst, ICW Fitzsimons, RA Fuck, DP Gladkochub, J. Jacobs, KE Karlstrom, S. Lul, LM Natapov, V. Pease, SA Pisarevsky , K. Thrane and V. Vernikovsky: Assembly, configuration, and break-up history of Rodinia: A synthesis. Precambrian Research, 160: 179-210, 2008 doi : 10.1016 / j.precamres.2007.04.021

Web links

Individual evidence

  1. ^ ZX Li, SV Bogdanova and others: Assembly, configuration, and break-up history of Rodinia: A synthesis. In: ScienceDirect, Precambrian Research, 160: 179-210, 2008 bdewaele.be PDF
  2. Scandinavia's geology website Kristallin.de
  3. Evolution of the Kibaran belt system in southwestern Africa ( Memento of the original from February 1, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Department of Geology, University of Botswana @1@ 2Template: Webachiv / IABot / www.st-andrews.ac.uk
  4. Evolution of the Namaqua-Natal Belt ScienceDirekt Journal of African Earth Sciences 46 (2006) 93-111
  5. ^ The Mesoproterozoic Irumide belt of Zambia ScienceDirekt Journal of African Earth Sciences 46 (2006) 36-70
  6. North China Kraton website Université Paris Sud
  7. Seismic Evidence for a Geosuture between the Yangtze and Cathaysia Blocks, South China website nature.com
  8. The India and South China cratons at the margin of Rodinia SienceDirekt Lithos Volume 123, Issues 1-4, April 2011, Pages 176-187
  9. The Río de la Plata Craton website Springer Link
  10. Yangtze Craton, Cathaysia and the South China Block Website Springer Link
  11. ^ Structure, evolution and palaeogeography of the West African craton and bordering belts during the Neoproterozoic ScienceDirect Precambrian Research Volume 69, Issues 1-4, October 1994, Pages 307-326
  12. ^ Archean Accretion and Crustal Evolution of the Kalahari Craton Journal of Petrologie April 8, 2009
  13. THE PROTEROZOIC HISTORY OF THE PROTO-CONGO CRATON OF CENTRAL AFRICA Department of Earth Sciences, Royal Museum for Central Africa, B-3080 Tervuren, Belgium
  14. The Saharan Metacraton Science Direct Journal of African Earth Sciences 34 (2002) 119-136
  15. ^ Archean crustal evolution of the northern Tarim craton, NW China ScienceDirekt Precambrian Research
  16. ^ Araban Shield website Saudi Geological Survey
  17. ^ The position of the Amazonian Craton in supercontinents Gondwana Research Volume 15, Issues 3-4, June 2009, Pages 396-407
  18. ^ Structure, evolution and palaeogeography of the West African craton and bordering belts during the Neoproterozoic Precambrian Research Volume 69, Issues 1-4, October 1994, Pages 307-326