Tectonic plates triggered a massive extinction 500 million years ago
A massive extinction known as the Sinsk event happened just as life expanded beyond parallel. Now scientists know that tectonic plates caused it.
The Cambrian period, which was 53.4 million years long between two ice ages, saw the biggest burst of life ever and produced sea creatures that look more like the future than the past. A massive extinction then followed known as the Sinsk event.
The Sinsk event killed off major groups including conical animals known as hyoliths with mustaches or curls for arms and sponges called archaeocyathids which look like cartoons. They diversified into hundreds of species that created the first reefs around the globe called the archaeocyathids reefs. They were destroyed by this cataclysmic event.
Researchers found fossils in Antarctica and Australia from the Sinsk event
Geologists already knew that falling levels of oxygen prompted the Sinsk event, but they didn’t know why that happened until now. Study leader Paul Myrow, a sedimentologist at Colorado College found that “oddly, it was tectonics that triggered an extinction.”
Myrow’s team studied trilobite fossils in 2011 from the extinct archaeocyathid reefs in Antarctica. About a decade later, Robert Gaines, a geologist from Pomona College, told them that he found similar rocks on Kangaroo Island in Australia with trilobite fossils. Trilobites, in particular, evolved so quickly that they can date a rock to stunning accuracy. These fossils date back to the Sinsk event because these animals went extinct.
“Everything clicked into place,” Myrow said. “There was the same geologic history all the way over in Australia as there was in Antarctica.”
The Sinsk event: As mountains rose, reefs fell
Antarctica and Southern Australia were once part of a supercontinent known as Gondwana that also included Africa, South America, and India. As tectonic shifted 600-540 million years ago, these reefs were destroyed after coming into existence in an incredible flourishing of life. Thanks to these trilobite fossils, they were able to pinpoint when the Sinsk event happened, around 513 million years ago, and it matched up with this massive geological shift.
Giant mountains thrusted into existence with the power of the Earth. The nearby shallow oceans dropped in a sea-saw motion. These reefs drowned under rock and debris that crushed them. Then, hot magma rose to the surface. It hardened and formed a geologic formation known as an igneous province. Water less rich in oxygen sunk to the bottom of the ocean as temperatures changed. That killed off many species. Scientists are concerned about climate change for that reason.
These large igneous provinces are linked to other extinctions. But, Myrow said, “I don’t know of any others that I could point to where it’s so clearly laid out.” So, the missing pieces came together, a true puzzle.
Now, researchers seem to be closer to being able to factually state that tectonic activity on the supercontinent of Gondwana brought an unprecedented and never-matched expansion of life that was followed by a massive extinction known as the Sinsk event because the rise of mountains drowned the archaeocyathid reefs.
Source: Interesting Engineering
Tectonic plates triggered a massive extinction 500 million years ago