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Topic: Supercontinent cycle

	Supercontinent cycle - Wikipedia, the free encyclopedia
		The supercontinent cycle describes the quasi-periodic aggregration and dispersal of Earth's continental crust.
		The Supercontinent cycle is the complement to the Wilson Cycle.
		This is the situation that was observed during the Paleozoic Supercontinent Cycle and is being observed for the Mesozoic-Cenozoic Supercontinent Cycle, still in progress.
	en.wikipedia.org /wiki/Supercontinent_cycle (986 words)

	Tectonic Pause: Towards the Unification of Earth Sciences - Karunakar Marasakatla
		This Supercontinent cycle repeats on the Earth as long as there is enough heat in the core to drive the convection in the mantle.
		The past six Manvantara cycles and the past six Earths are the past six Supercontinent cycles and the present Manvantara or the seventh Earth started with the breakup of the Pangaea around 250 Ma.
		The salty ocean was the water around the Supercontinent and the fresh ocean was the water from the melting ice sheets after the breakup of the Supercontinent.
	www.geocities.com /karunakarm/unifiedtheory.html (8181 words)

	News story: Supercontinents and snowball Earth events
		Supercontinent formation is a collision and merger of multiple continents.
		Each Manvantara cycle lasts for approximately 308 million years and the age of the Earth was mentioned as 2 billion years.
		Appropriate time period for the seven Supercontinent cycles is another 3 billion years and this time is in accordance with the present standards of the Earth and planetary sciences for the hospitable environment to continue on the Earth.
	www.geocities.com /karunakarm/press062501.html (1116 words)

	Global Tectonic Cycles
		Cycle duration (period) seems to lie in the range of 400 to 500 million years.
		Ocoee meta-sediments (in the Cohutta mountains) probably were deposited in rift basins during breakup of Pangea's ancestor supercontinent.
		Cycle period may be other than 450 million years, or perhaps not all cycles have the same duration.
	home.att.net /~cochrans/tectcy01.htm (443 words)

	A synopsis of plate tectonics
		The cycle begins with a supercontinent perched on one side of the earth, balanced on the other side by a superocean.
		The supercontinent fragments, sending small continental pieces across the ocean to collide to form another supercontinent on the opposite side of the earth.
		This supercontinent cycle does not just go round and round, however, for with each cycle new continental crust is generated, and the continents get bigger.
	csmres.jmu.edu /geollab/Fichter/PlateTect/synopsis.html (1023 words)

	Wilson cycle introduction
		The supercontinent cycle maps out the large scale history of the earth, the formation and fragmentation of the continents, within an overall evolutionary enlargement of the total size of the continents with each cycle.
		Note that they come together in the Wilson Cycle where the six tectonic regimes of the lithosphere can be said to have been constructed inductively from observation, or to exist logically through plate tectonic theory.
		The Wilson cycle brings together all the processes of plate tectonics, and all the processes by which individual rocks are generated, and uses them to tell a plausible story of how plate tectonic theory and individual minerals and rocks are related.
	csmres.jmu.edu /geollab/Fichter/PlateTect/wilsonintro.html (846 words)

	k35 The supercontinent cycle (Site not responding. Last check: 2007-10-11)
		However, the high end of the 270 to 715 My range is exceeded if the clustering of radiometric ages of times of crystallization of shield rocks do indicate a supercontinent formed about 1800 Ma and one, that was breaking up as it was forming elsewhere, existed about 2600 Ma.
		The supercontinents themselves evidently have a short duration of 50 ±50 My or are never wholly formed and are breaking up in one place as they are forming elsewhere.
		Fragmentation of a supercontinent is not along lines of prior continent sutures except by chance, locally, and there only approximately.
	geowords.com /histbooknetscape/k35.htm (571 words)

	sciforums.com - Explanation for Pangea?
		Supercontinents did not come and go in cycles in the beginning because they depended on too many variable and unknown factors when the earth was forming.
		The short "abstract" of the article you cited was very interesting but if you notice it only referrs to Pangaea 300 mya and on: no reference to their supposed h hypothetical "three billion years, in a process known as the supercontinent cycle." I think this is pure spectulation - no proof, no evidence.
		Also, Earth's continents are formed by plate tectonics, but the reason that we have a difference between land mass and ocean floor crust is because of the differences between the density of the rock (isostasy).
	www.sciforums.com /printthread.php?t=50652 (2218 words)

	The Supercontinent Cycle (Site not responding. Last check: 2007-10-11)
		Supercontinents are the collection of all the Earth's continents compressed together.
		The Wilson cycle is the process by which continents rift, spread apart, and form ocean basins.
		Scientist believe geologic events such as these, as well as the current rates of sea floor spreading, fit a cycle of events that have reoccured every 440 million years throughout Earth's history.
	www.emporia.edu /earthsci/student/stitz (306 words)

	Earth and Space Science \| Session 2
		The first known supercontinent is called Rodinia (from Russian, meaning "homeland"), and it is thought to have formed about 1.1 billion years ago.
		Although the exact size and configuration of Rodinia cannot be estimated, rocks of ancestral North America are thought to have formed the core of the giant continent.
		This supercontinent cycle is called the Wilson Cycle after J. Tuzo Wilson, the Canadian geologist who first described it.
	learner.org /channel/courses/essential/earthspace/session2/closer3.html (400 words)

	Essentials of Geology : Chapter 19 : Overview
		The sea-level cycle: The sea’s transgressions and regressions have left a physical record of major sedimentary sequences and their minor subdivisions called cyclothems.
		The rock cycle: Earth’s internal processes (including rifting, mantle plumes, subduction, sea-floor spreading, and convergence) and external processes (including weathering, erosion, and deposition) cycle the atoms of minerals through the three basic rock types (igneous, sedimentary, and metamorphic).
		The hydrologic cycle: Water may exist in any of its states (gas, liquid, or solid) as it cycles through the oceans, atmosphere, surface water, groundwater, glaciers, soil, and living organisms.
	www.wwnorton.com /earth/egeo/overview/ch19.htm (956 words)

	Resource Description: item 1490
		The theory of continental drift and the supercontinent, Pangaea, was first proposed in 1912.
		Researchers are now speculating that every 500 million years the continents assemble into a single supercontinent.
		The tectonic interactions associated with the formation and breakup of such supercontinents provide a new way to view the origin of the Earth's mountain belts.
	infocus.sl.nsw.gov.au /res/resdesc.cfm?res_code=1490 (78 words)

	ScienceWeek
		Although the mechanisms responsible are controversial, many geoscientists agree that repeated cycles of supercontinent amalgamation and dispersal have not just taken place, but also have had a profound effect on the evolution of the Earth's crust, atmosphere, climate and life over billions of years.
		First, the break-up of Rodinia is heralded by, and accompanied by, the eruption of large basaltic provinces, resulting in an increase of the weatherability of the continental surface and consumption of atmospheric CO2 on the 10^(6)-yr timescale.
		The existence of a supercontinent in the Precambrian (before 544 million years ago) was proposed in the 1970s, when many geologists noted a large number of mountain belts with similar ages (1300 to 1000 million years old) that are today located on different continents.
	scienceweek.com /2004/sa040730-5.htm (1424 words)

	Geologic Cycles & Events
		The Pan-African orogenic cycle is approximately correlative with the Sauk
		orogenic cycles (E), and tectonic phases of the supercontinent cycles (F).
		Much of the Pangean supercontinent was located in lower subtropical to tropical latitudes (Figure 10D).
	www.geocomplexity.com /Global_cycles.htm (5790 words)

	Geology 105 - Lecture Key Points (Site not responding. Last check: 2007-10-11)
		Sutures are marked by reverse faults, highly contorted rocks, oceanic rocks such as pillow basalts, and slices of the Earth's mantle.
		As subduction progresses, the old rifted edges of the old supercontinent are brought back together until they collide and become stitched together again into another supercontinent.
		At some later time, when a new hotspot begins to rise, rifting of the supercontinent will occur again – typically at the weakest points within the supercontinent – the old suture zones.
	faculty.washington.edu /sechern/key/041122.html (327 words)

	Bryson Burke Diamond Corporation: Diamond Exploration and Mining in Canada
		Togther they formed a supercontinent named Pangea that persisted only for a brief 70 million years or so before Africa and North America parted ways.
		Fit in supercontinent not clear, but likely represents subduction along the west side of Rodinia.
		As described the super continent cycle is far reaching.
	brysonburke.com /grenville_supercontinent_theory.html (775 words)

	Adult Articles (Site not responding. Last check: 2007-10-11)
		Earth's continents are thought to be undergoing a long cycle of colliding and separating: during the period of continental assembly continental crust collides, merges, and forms new continents; and during continental fragmentation continental crust is separated by deep rifts that become centers of new ocean basins.
		During the time that sea level is low (when the world is dominated by a single supercontinent or when the continents are widely dispersed and the ocean floor is the oldest) large amounts of silicate minerals in the continental crust are dissolved and carried to the oceans.
		In the past the different stages of the supercontinent cycle have also influenced patterns of weather and climate, the composition of the atmosphere and oceans, glaciation, and ocean circulation.
	www.cfmsinc.org /Newsletter/News1999/awards99/aa.htm (20607 words)

	Self-Service Science Forum Message (Site not responding. Last check: 2007-10-11)
		This cycle of supercontinents and continents has controlled the climate on our planet, and has ultimately chosen what sort of life we see here on earth.
		This brand-new theory about recycling the supercontinents is put forward by 3 scientists having separate specialities in the fields of Plate Movements, Oceanography and Geochemistry.
		As the supercontinents broke apart, vast areas of tropical coastline were created, and the weather reports became finer and milder.
	www2.abc.net.au /science/k2/stn-archive1/posts/topic6642.shtm (1189 words)

	GEOL 102 Orogenesis II (Site not responding. Last check: 2007-10-11)
		The sequence of events (and resulting lithologies) described last lecture has been called a Supercontinent Cycle (or a Wilson Cycle, after J. Tuzo Wilson, who linked spreading centers and subduction zones).
		Wilson Cycles are the largest scale manifestations of crustal cyclical processes.
		Wilson Cycles have been in operation since the origin of modern-style tectonics, and will operate as long as the core continues to generate sufficient heat (i.e., as long as its fissionable "fuel" holds out).
	www.geol.umd.edu /~tholtz/G102/102oro2.htm (113 words)

	THE EARLY TRIASSIC AND THE SUPERCONTINENT CYCLE
		Because a supercontinent acts as an insulator that traps mantle heat, once Pangea formed the mantle began heating up and producing basaltic magma that rose to the surface.
		Formation of flood basalts and large igneous provinces was common from the later part of Pangea’s existence into the subsequent breakup, and this time interval was also marked by significant increases in atmospheric carbon dioxide.
		Thus the end-Permian mass extinction and Early Triassic represent the most severe of the Pangean biotic crises, and the bottleneck which the effects of this supercontinent produced on metazoan life is still manifest today.
	gsa.confex.com /gsa/2004AM/finalprogram/abstract_75435.htm (499 words)

	Geology of the North American Craton
		The relative disposition of continental fragments during the dispersal phase of a supercontinent cycle can be examined in terms of the intercontinental migration patterns of shallow marine faunas such as brachiopods and trilobites.
		In this respect, care should be taken not to confuse transgressions of the seas due to sea level rise on a tilted surface with transgressions related to the tilting itself.
		During supercontinent breakup continents get that sinking feeling because they move off the positive thermal anomaly that keeps them buoyant while they are part of a thermally insolated supercontinent.
	instruct.uwo.ca /earth-sci/300b-001/nacraton.htm (3717 words)

	plate lecture - fossil evidence and effects of plate motions
		Gondwana and Pangeae are large continental masses (super continents) that formed and split apart.
		So in addition to the Wilson cycle, which explores the type of history we would expect on a continent scale, there is a proposed supercontinent cycle that is thought to have occurred on a global scale.
		Break up into groups of four and work on developing a cycle diagram that depicts how biogeographic patterns would change with the continental configuration, a la the Wilson and supercontinent cycle.
	maps.unomaha.edu /maher/plate/week10/life.html (1338 words)

	Continental Drift
		· However, nowadays most geologists are convinced there exists a supercontinent cycle in which landmasses separate and move, collide and merge.This process has maybe repeated itself several times.
		· An earlier hypothesis of continental drift stated that many years ago the supercontinent of Pangaea fragmented into lesser continents that slowly drifted to reach their current position.
		· Mountain ranges appear to have become discontinuous when the supercontinent broke apart.
	www.yorku.ca /apanahi/1750/chapter7.htm (886 words)

	Mendenhall Postdoctoral Research Fellowship Program: Research Opportunities
		A critical first step in any continental-scale resource assessment of such reworked crustal blocks is to reassemble the pieces to their original, syn-mineral formation configurations.
		Presently, we are attempting to identify and assess contained resources within metallogenic provinces in the context of pre-Mesozoic(?) supercontinent growth.
		Newly developed global reconstruction scenarios are being used to evaluate and to derive the most plausible configurations of Pangea, Rodinia, and other hypothesized older supercontinents.
	geology.usgs.gov /postdoc/2004/opps/opp10.html (995 words)

	Plate lecture - supercontinents.
		Together they formed a supercontinent named Pangea that persisted only for a brief 70 million years or so before Africa and North America parted ways.
		Importance of Grenville rocks in reconstructions of Rodinia supercontinent: assembly mark.
		Dalziel, I. D., 1991, Pacific margins of Laurentia and East Antarctica-Australia as a conjugate rift pair: Evidence and implications for an Eocambrian supercontinent.
	maps.unomaha.edu /maher/plate/week12/super.html (1350 words)

	Naked Earth: The New Geophysics - PowerBookSearch!
		It is common knowledge that the continents once formed a giant landmass, called Pangaea, 180 million years ago, yet many readers will be unfamiliar with the Supercontinent Cycle?the belief, now shared by many geophysicists, that the Pangaean supercontinent was a recurrent, not a one-time, phenomenon.
		Furthermore, the existence of Pangaea seems to be stored like a memory in inner Earth's rocks and may be dictating where enormous floods of magma (molten rock) erupt.
		It is common knowledge that the continents once formed a giant landmass, called Pangaea, 180 million years ago, yet many readers will be unfamiliar with the Supercontinent Cycle-the belief, now shared by many geophysicists, that the Pangaean supercontinent was a recurrent, not a one-time, phenomenon.
	www.powerbooksearch.com /booksearch0525937714.html (866 words)

	The Geology of Stratigraphic Sequences:3540593489:Miall, Andrew D.:eCampus.com
		Cycles with Episodicities of Tens of Millions of Years
		Cycles with Episodicities of Less Than One Million Years
		Cycles with Episodicities of Tens to Hundreds of Millions of Years
	www.ecampus.com /bk_detail.asp?isbn=3540593489 (329 words)

	TECTONIC HISTORY OF RODINIA: CONSTRAINTS FROM STRONTIUM AND CARBON ISOTOPES AND CONTINENTAL CRUST PRODUCTION RATES (Site not responding. Last check: 2007-10-11)
		Possible fragmentation of a Paleoproterozoic supercontinent between 1.6 and 1.4 Ga correlates with only a weak decrease in the 87Sr/86Sr ratio of seawater (0.706 to 0.705), little or no change in
		The fact that Sr and C isotopes and crustal production rate show only a weak imprint of supercontinent fragmentation at 1.6-1.4 suggests that the Paleoproterozoic supercontinent underwent only minor breakup at this time.
		Meso to Neoproterozoic of the Western US: Record of Supercontinent Assembly and Breakup, and a Snowball Earth?
	gsa.confex.com /gsa/2001RM/finalprogram/abstract_5717.htm (332 words)

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