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A major extinction in the midst of a immense expansion of life on Earth may have been drive byplate tectonics .
New research finds link between rock layer in Antarctica and Southern Australia , which at the time were part of the supercontinent Gondwana . This advise that like kinetics were occurring aroundthe supercontinentroughly 513 million years ago : Mountains were uplifting , ancient reefs were dying , and erode material from the continent was pouring into the sea . These instant in time coincide with the defunctness cognise as the Sinsk event , say study leaderPaul Myrow , a sedimentologist at Colorado College .
Trilobite fossils recovered from the Transantarctic Mountains.
" peculiarly , it was plate tectonic theory that set off an extinction , " Myrow told Live Science .
The Sinsk effect occur during the Cambrian period ( 540 million to 485 million years ago ) , which saw a Brobdingnagian diversification of life onEarthknown as theCambrian explosion .
But in the middle of this brandish , the Sinsk extinction killed off several major groups , including cone - shelled animate being called hyoliths and sponges called archaeocyathids , which once built tremendous reefs all over the globe . Researchers know that the Sinsk case was linked to fall levels of oxygen in the oceans , but they have n’t been able to pinpoint the precise cause .
A map showing the positions of Australia and Antarctica in the Gondwanan supercontinent.
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Now , Myrow and his colleagues say they have the result . The tectonics of Gondwana , which formed between 600 million and 540 million year ago , trigger off a series of events that drowned the archaeocyathid reef and altered the oceans , they report March 29 in the journalScience Advances .
The clue to these event was found in rock bed in Antarctica ’s Transantarctic Mountains and on Kangaroo Island , Australia . Myrow and his fellow pile up samples in Antarctica in 2011 , including trilobite fogy from long - dead archaeocyathid reefs . Then , about a year ago , Pomona College geologistRobert Gainestold Myrow he ’d seen like rocks on Kangaroo Island , which is also studded with fossil trilobite .
These trilobite were the key to the timing of the loss of the reefs . Because trilobitesevolvedquickly , researcher can state how previous a careen is by the coinage of trilobite fossilized inside it . In both Antarctica and Australia , the fogy dated to between 514 million and 512 million years ago — properly around the fourth dimension of the Sinsk event .
" Everything clicked into place , " Myrow said . " There was the same geologic story all the way over in Australia as there was in Antarctica . "
At the time of the Sinsk effect , both continents were part of Gondwana , with today ’s Antarctica sitting on the equator and Australia at a higher parallel . The locations showed a like tarradiddle in the rock and roll layer . The extinction of the archaeocyathid Witwatersrand coincided with gargantuan mountain - edifice events . As the mountains pop up on kingdom , the nearby shallow ocean right off the coast settle in a kind of seesaw motion of the crust . This make the archaeocyathid reefs to suddenly deepen , submerging them past their power to survive . Next , erosion from the new mountain ranges dump layer of cobbles and crushed rock over the submerge reefs .
Meanwhile , Myrow say , the architectonic movements that caused slew to lift in some place also caused the incrustation to stretch out in others , allowing magma to rise to the surface and harden into the rock basalt , a geologic formation known as a “ large igneous province . ” These hot magmas convey lots ofgreenhouse gas , like sulfur dioxide and carbon dioxide , induce Earth ’s atmosphere to warm up .
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This warming , in turn , slowed the circulation in the ocean — a phenomenon that researchers worrymay occur again todaywith human - inducedclimate modification . This slowdown of sea circulation led less - atomic number 8 - rich water to sink to the sea bottom . This kill off many existing organisms , Myrow said .
" The old , more primitive ones did n’t do so well , " he say .
Large igneous state have been blamed for other extinctions , but with less certainty than the Sinsk event , Myrow said , " I do n’t know of any others that I could point to where it ’s so intelligibly laid out . "
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