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Encyclopedia > Kenorland

Kenorland was one of the earliest supercontinents found on Earth. It was formed during the Neoarchaean Era ~2.7 billion years ago by the accretion of Neoarchaean sanukitoid cratons and the formation of new continental crust. It comprised the Laurentia, Baltica, Australia, and Kalahari cratons. Tectonic magma-plume rifting began to occur between 2.48 to 2.45 Ga. The protracted breakup of Kenorland during the Late Neoarchaean and early Paleoproterozoic Era 2.48 to 2.10 Ga, during the Siderian and Rhyacian periods, is manifested by mafic dykes and sedimentary rift-basins on many continents. On early Earth, this type of bimodal deep mantle plume rifting is thought to have been common in Hadean, Archaean and Neoarchaean crust and continent formation, but the geological time period surrounding the break up of Kenorland is thought by most geologists to be the beginning of the transition point to the subsequent two-layer core-mantle plate tectonics convection theory that is commonly accepted today. In geology, a supercontinent is a land mass comprising more than one continental core, or craton. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... A geologic era is a subdivision of geologic time that is a separate classification that divides the Phanerozoic Eon into three parts timeframes. ... A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. ... North American craton. ... Baltica is the craton beneath northwestern Eurasia. ... The Kalahari Desert is a large, arid to semi-arid sandy area in southern Africa that covers about 500,000 km². It covers 70% of Botswana, and parts of Zimbabwe, Namibia and South Africa. ... A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. ... Magma is molten rock located beneath the surface of the Earth (or any other rocky planet), and which often collects in a magma chamber. ... The Archean (Archaean; previously known as the Archaeozoic or Archeozoic) is a geologic eon that refers to the time before the Proterozoic, 2500 Ma (million years ago). ... In geology, the Proterozoic is an eon prior to the first abundant complex life on Earth. ... The Siderian (from Greek sideros, iron) is the first geologic period in the Paleoproterozoic Era and lasted from 2500 million years ago to 2300 million years ago. ... From the GeoWhen Database: Rhyacian Period From 2300 +/- 0 To 2050 +/- 0 Ma Start Defined By: Fixed Date End Defined By: Fixed Date Start Based On: Gradstein, Ogg, Smith, et. ... In geology, mafic minerals and rocks are silicate minerals, magmas, and volcanic and intrusive igneous rocks that have relatively high concentrations of the heavier elements. ... Dyke (normal International spelling) or Dike (normal American spelling) can mean several things: A dyke / dike is a long wall built to keep out the sea or enclose land. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... The name Hadean refers to the geologic period before 3800 million years ago (mya). ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... The Archean (Archaean; previously known as the Archaeozoic or Archeozoic) is a geologic eon that refers to the time before the Proterozoic, 2500 Ma (million years ago). ... Bridge across the Álfagjá rift valley in southwest Iceland, the boundary of the Eurasian and North American continental tectonic plates. ...


Paleomagnetic studies show Kenorland was in generally low latitudes until the rifting breakup began 2.48 Ga. Paleomagnetic evidence shows that at 2.45 Ga the Fennoscandian Shield was joined to Laurentia and formed a unity with both the Kola and Karelia Cratons, and that the Fennoscandian Shield was located over the equator. The Kola and Karelia cratons began to drift apart ~2.45 Ga, and by 2.4 Ga the Kola craton was located at ~15 degrees latitude and the Karelia craton was located at ~30 degrees latitude. However, paleomagnetic evidence also shows that the Yilgarn craton (now the bulk of Western Australia) was not connected to Fennoscandia-Laurentia and at 2.45 Ga it was located at ~70 degrees latitude. This implies that at 2.45 Ga there was no longer a supercontinent and by 2.4 Ga an ocean existed between the Kola and Karelia cratons. Paleomagnetism refers to the orientation of the Earths magnetic field as it is preserved in various magnetic iron bearing minerals throughout time. ... The Baltic Shield (or Fennoscandian Shield) is a segment of the Earths crust belonging to the East European Craton, representing a large part of Scandinavia, northwestern Russia and the northern Baltic Sea. ... North American craton. ... Kola can refer to: Kola nut Kola Peninsula, in the far north of Russia Kola Island, part of the Aru Islands of Indonesia Kola language, spoken on Kola Island Mr. ... Map showing the parts Karelia is traditionally divided into. ... The Yilgarn Craton is a craton which constitutes the bulk of the Western Australian land mass. ...


The breakup of Kenorland was contemporary with the Huronian glaciation which lasted for over 60 million years. The Banded-Iron Formations(BIF) show their greatest extent at this period, indicating a massive increase in oxygen build-up from an estimated 0.1% of the atmosphere to 1%. The rise in oxygen levels caused the virtual disappearance of the greenhouse gas methane (oxidized into carbon dioxide and water). The simultaneous breakup of Kenorland generally increased continental rainfall everywhere, thus increasing erosion and further reducing the other greenhouse gas, carbon dioxide. With the reduction in greenhouse gases, and solar output being less than 85% its current power, led to a runaway Snowball Earth scenario, where average temperatures planetwide plummeted to below freezing. Despite the anoxia indicated by the BIF, photosynthesis continued, stabilizing climates at new levels during the second part of the Proterozoic Era. The Huronian glaciation was from 2400 mya to 2100 mya, during the Siderian and Rhyacian periods of the Paleoproterozoic era. ... A glaciation (a created composite term meaning Glacial Period, referring to the Period or Era of, as well as the process of High Glacial Activity), often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ... 2. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... The simplest hydrocarbon, methane, is a gas with a chemical formula of CH4. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect. ... The Snowball Earth hypothesis attempts to explain a number of phenomena noted in the geological record by proposing that an ice age that took place in the Neoproterozoic was so severe that the Earths oceans froze over completely, with only heat from the Earths planetary core causing some... A scenario (from the Italian, that which is pinned to the scenery) is a brief description of an event. ... Asphyxia is a condition of severely deficient supply of oxygen to the body. ...


References

Ramo, O.T., Halla, J., Nironen, M., Lauri, L.S., Kurhila, M.I., Kapyaho, A., Sorjonen-Ward, P., & Aikas, O., (2005). "Eurogranites 2005 - Proterozoic and Archean Granites and Related Rocks of the Finnish Precambrian". Online at: http://www.helsinki.fi/geology/files/Eurogranites2005.pdf


Mertanen, Satu (2004). "Paleomagnetic Evidences for the Evolution of the Earth during Early Paleoproterozoic". Symposium EV04: Interaction of Endogenic, Exogenic and Biological Terrestrial Systems. Online: http://www.the-conference.com/JConfAbs/6/EVO4.pdf


Pesonen, L.J., Elming, S.-Å., Mertanen, S., Pisarevsky, S., D’Agrella-Filho, M.S., Meert, J.G., Schmidt, P.W., Abrahamsen, N. & Bylund, G., (2003}. "Palaeomagnetic configuration of continents during the Proterozoic". Tectonophysics 375, 289-324.

Continents of the world


Africa-Eurasia

Americas

Eurasia


Africa

Antarctica

Asia

Australia

Europe

North America

South America

Geological supercontinents :  Gondwana · Laurasia · Pangaea · Pannotia · Rodinia · Columbia · Kenorland · Ur


 
 

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