What caused the supercontinent of Pangea to split apart?
Pangaea: Facts about an ancient supercontinent
About 300 million years ago, Earth didn't have seven continents, merely instead ane massive supercontinent called Pangaea, which was surrounded by a single sea called Panthalassa.
The explanation for Pangaea'south germination ushered in the modern theory of plate tectonics, which posits that the Globe's outer shell is cleaved up into several plates that slide over Earth's rocky shell, the mantle.
Over the course of the planet's 4.v billion-twelvemonth history, several supercontinents have formed and broken upwardly, a result of churning and circulation in the Earth's mantle, which makes up 84% of the planet's volume, co-ordinate to the U.South. Geological Survey (opens in new tab). This breakup and formation of supercontinents has dramatically altered the planet'south history.
"This is what'south driven the unabridged evolution of the planet through time. This is the major backbeat of the planet," said Brendan White potato, a geology professor at the St. Francis Xavier University, in Antigonish, Nova Scotia.
Pangaea'south history
More than a century ago, the scientist Alfred Wegener proposed the notion of an aboriginal supercontinent, which he named Pangaea (sometimes spelled Pangea), after putting together several lines of evidence.
The first and most obvious was that the "continents fit together like a tongue and groove," something that was quite noticeable on whatever accurate map, Potato said. Another telltale hint that Earth'south continents were all ane land mass comes from the geologic record. Coal deposits found in Pennsylvania have a like composition to those spanning beyond Poland, Great Great britain and Germany from the same time flow. That indicates that North America and Europe must have once been a single landmass. And the orientation of magnetic minerals in geologic sediments reveals how Earth'southward magnetic poles migrated over geologic time, Tater said.
In the fossil tape, identical plants, such as the extinct seed fern Glossopteris, are found on now widely disparate continents. And mount chains that now prevarication on dissimilar continents, such as the Appalachians in the United States and the Atlas Mountains spanning Morocco, Algeria and Tunisia were all part of the Central Pangaea Mountains, formed through the collision of the supercontinents Gondwana and Laurussia.
The word "Pangaea" comes from the Greek "pan," which means "all," and "gaia" or "Earth," co-ordinate to the Online Etymology Dictionary (opens in new tab). The supercontinent formed through a gradual process spanning a few hundred million years.
In the early Phanerozoic eon (541 meg years ago to now), almost all of the continents were in the Southern Hemisphere, with Gondwana, the largest continent, spanning from the South Pole to the equator, according to a chapter in the scientific volume "Ancient Supercontinents and the Paleogeography of Globe (opens in new tab)" (Elsevier, 2021). The Northern Hemisphere was largely covered by the Panthalassic Bounding main. Some other sea — called Iapetus, after a mythical Greek titan — between the paleo-continents Laurentia, Baltica and Gondwana, began to close during the Ordovician menses (485 million to 444 one thousand thousand years ago) and then disappeared during the Silurian period (444 million to 419 meg years agone), when Baltica and Avalonia collided with Laurentia to form Laurussia, according to the affiliate, "Phanerozoic paleogeography and Pangea (opens in new tab)."
Finally, about 320 million years ago, there was a major collision, geologically speaking, "when Gondwana, Laurussia, and intervening terranes collided to class the Pangea supercontinent," according to the affiliate, written by Earth scientists Trond Torsvik, Mathew Domeier and Robin Cocks.
Even so, Pangaea wasn't the megalithe most people call back information technology is. "Pangea never included all the continents at whatever one time," according to the chapter. For instance, "the Paleotethys Ocean to the due east of Pangea remained wide throughout the Carboniferous [359 1000000 to 299 million years agone] and presented something of a barrier between the supercontinent and a number of large, independent Asian terranes, including Tarim, North China, South China, and Annamia."
Subsequently, during the Permian period (299 million to 251 meg years agone), "many former peri-Gondwanan terranes drifted off the due north-east Gondwana margin, commencing the opening of the Neotethys Bounding main," according to the affiliate.
When did Pangaea intermission autonomously?
Pangaea broke up in several phases betwixt 195 million and 170 meg years agone. The breakup began most 195 one thousand thousand years agone in the early on Jurassic menstruation, when the Fundamental Atlantic Ocean opened, according to the chapter. The supercontinent fractured largely along previous sutures.
Gondwana (what is now Africa, Southward America, Antarctica, Republic of india and Australia) first split from Laurasia (Eurasia and North America). And so about 150 million years ago, Gondwana bankrupt up. Republic of india peeled off from Antarctica, and Africa and Due south America rifted, co-ordinate to a 1970 commodity in the Periodical of Geophysical Research (opens in new tab). Around lx million years agone, North America split off from Eurasia.
Pangaea's climate
Having one massive landmass made for very unlike climatic cycles. For instance, the interior of the continent may accept been utterly dry, as it was locked behind massive mount chains that blocked all moisture or rainfall, Murphy said.
But the coal deposits found in the Us and Europe reveal that parts of the ancient supercontinent near the equator must take been a lush, tropical rainforest, similar to the Amazonian jungle, Murphy said. (Coal forms when dead plants and animals sink into swampy water, where pressure and water transform the cloth into peat, then coal.)
"The coal deposits are essentially telling us that there was plentiful life on land," Murphy told Live Science.
Climate models ostend that the continental interior of Pangaea was extremely seasonal, according to a 2016 commodity in the periodical Palaeogeography, Palaeoclimatology, Palaeoecology (opens in new tab). The researchers in this report used biological and physical information from the Moradi Formation, a region of layered paleosols (fossil soils) in northern Niger, to reconstruct the ecosystem and climate during the time period when Pangaea existed. Comparable with the modern-twenty-four hours African Namib Desert and the Lake Eyre Basin in Australia, the climate was generally arid with short, recurring wet periods that occasionally included catastrophic flash floods.
The climate besides influenced where animals lived. During the late Triassic, Reptile-like animals in the family unit Procolophonidae lived in 1 region, while mammal relatives, known as cynodonts, lived in another, a 2011 written report in the periodical Proceedings of the National Academy of Sciences (opens in new tab) found. Cynodonts inhabited ane tropical area of Pangaea, where monsoon-like rains fell twice a yr. Upwardly north, procolophonids lived in temperate regions where it only rained in one case a year. It's probable that the cynodonts needed a water-rich area, which restricted their movements on Pangaea, the researchers said.
"It's interesting that something as bones as how the body deals with waste tin can restrict the move of an entire grouping," Whiteside said in a statement (opens in new tab). In drier areas, "the reptiles had a competitive advantage over mammals," which is probable why they stayed in that location, Whiteside said.
Pangaea animals
Pangaea existed for more than than 100 million years, and during that time many creature groups thrived. During the Permian menses, insects such every bit beetles and dragonflies flourished, as did the predecessors of mammals: the synapsids. But the existence of Pangaea overlapped with the worst mass extinction in history, the Permian-Triassic (P-TR) extinction event. Likewise called the Great Dying, it occurred around 252 million years agone and caused 96% of all marine species and around 70% of terrestrial species to get extinct, according to the Geological Club of America (opens in new tab).
The early Triassic period saw the ascension of archosaurs, a group of animals that eventually gave rise to crocodiles, birds and a plethora of reptiles, including pterosaurs. And well-nigh 230 million years agone some of the primeval dinosaurs emerged on Pangaea, including theropods, largely cannibal dinosaurs that by and large had air-filled basic and feathers like to birds.
Wheel in history
The current configuration of continents is unlikely to be the last. Supercontinents have formed several times in Earth's history, only to be split off into new continents. Right at present for instance, Australia is inching toward Asia, and the eastern portion of Africa is slowly peeling off from the rest of the continent.
Based on the emergence of other supercontinents in the Precambrian supereon (4.five billion to 541 million years ago), information technology appears that supercontinents occur periodically every 750 million years, according to a 2012 report in the periodical Gondwana Research (opens in new tab).
Well-nigh scientists believe that the supercontinent wheel is largely driven past circulation dynamics in the mantle, according to a 2010 article in the Journal of Geodynamics (opens in new tab).
Beyond that, the details go fuzzy. While the heat formed in the mantle likely comes from the radioactive decay of unstable elements, such as uranium, scientists don't hold on whether there are mini-pockets of heat menstruum inside the mantle, or if the entire crush is one big heat conveyor belt, Spud said.
Current research on Pangaea
Scientists have created mathematical, 3D simulations to better understand the mechanisms behind continental motility. In a 2018 commodity in the periodical Geoscience Frontiers (opens in new tab), Globe scientists Masaki Yoshida and M. Santosh explained how they produced simulations of large-scale continental movements since the breakup of Pangaea about 200 million years ago. The models show how tectonic plate motion and curtain convection forces worked together to break apart and movement large land masses. For example, Pangaea's large mass insulated the mantle underneath, causing mantle flows that triggered the initial breakup of the supercontinent. Radioactive decay of the upper mantle too raised the temperature, causing upward pall flows that bankrupt off the Indian subcontinent and initiated its northern motility.
Yoshida and Santos created boosted geological models to predict mantle convection and continental movement patterns 250 one thousand thousand years in the time to come. These models suggest that over millions of years, the Pacific Bounding main volition close as Australia, N America, Africa, and Eurasia come together in the Northern Hemisphere. Eventually, these continents will merge, forming a supercontinent called "Amasia." The two remaining continents, Antarctica and South America, are predicted to remain relatively immobile and split up from the new supercontinent.
Boosted reporting by Carol Stoll, Live Science contributor
Additional resources
- Enroll in the free online Cousera grade "Our Earth: Its Climate, History, and Processes (opens in new tab)" offered past the University of Manchester in the U.G.
- U.S. Geological Survey: This Dynamic World: The Story of Plate Tectonics (opens in new tab)
- Cheque out this interactive map (opens in new tab) that shows where modern countries could have sat on the Pangaea supercontinent.
Bibliography
Alive Science. "What is plate tectonics?" May 26, 2021.
U.S. Geological Survey. "The Interior of the Earth (opens in new tab)." Last modified Jan. 14, 2011.
Online Etymology Dictionary. "Pangaea (opens in new tab)."
Torsvik, T.H., et al. "Affiliate xviii - Phanerozoic paleogeography and Pangea (opens in new tab). 2021.
Robert Southward. Dietz,John C. Holden. Journal of Geophysical Research (opens in new tab). 1970.
Looy, C.5. et al. Palaeogeography, Palaeoclimatology, Palaeoecology (opens in new tab). 2016.
Jun Liu and Fernando Abdala. "Early Evolutionary History of the Synapsida (opens in new tab)." Sept. 21, 2013.
Geological Society of America. "The "Great Dying (opens in new tab)." May 19, 2021.
Whiteside, J.H., et al. Proceedings of the National Academy of Sciences (opens in new tab). 2011.
Brown University. "On Pangaea, the supercontinent, breadth and rain dictated where species lived (opens in new tab)." May 12, 2011.
Joseph G. Meert. Gondwana Research (opens in new tab). 2012.
Yard. Santosh. Periodical of Geodynamics (opens in new tab). 2010.
Masaki Yoshida and One thousand. Santosh. Geoscience Frontiers (opens in new tab). 2018.
Source: https://www.livescience.com/38218-facts-about-pangaea.html
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