Privileged Planet: plate tectonics driving evolution (Introduction)

by David Turell , Friday, May 31, 2024, 18:19 (108 days ago) @ David Turell

A long study at two points:

https://phys.org/news/2024-05-mountain-linked-major-extinction-event.html

"As life on Earth rapidly expanded a little over 500 million years ago during the Cambrian explosion, Earth had tectonic plates slowly crashing into each other, building mountains and starting a series of unfortunate events that led to a mass extinction.

"These plate interactions further led to magma rising to the Earth's surface, large amounts of greenhouse gases entering the atmosphere, and rapid climate change. The resulting extinction decimated animal groups, like archaeocyathids (reef-building marine sponges) and hyoliths (animals with small conical shells).

"It's unusual to point to a tectonic cause for an extinction event," said John Goodge, a professor emeritus at the University of Minnesota Duluth, "but the evidence is compelling."

"Goodge and his colleagues realized the link to plate tectonics after comparing field notes from sites in Antarctica and southern Australia. They noticed that the two locations, which were once near each other around the equator as part of the supercontinent Gondwana, had nearly identical records of mountain building right before the extinction.

***

"It all started when Goodge and fellow scientists set up their bright yellow and blue tents on a snow-covered glacier in Antarctica. Over two field seasons, they traveled by helicopter and snowmobile to the Holyoake Range and examined fossils from the carbonate reef structures to pinpoint the extinction. A separate team found similar records in Australia in 2011."

The paper:

https://www.science.org/doi/10.1126/sciadv.adl3452

"The Cambrian explosion, one of the most consequential biological revolutions in Earth history, occurred in two phases separated by the Sinsk event, the first major extinction of the Phanerozoic. Trilobite fossil data show that Series 2 strata in the Ross Orogen, Antarctica, and Delamerian Orogen, Australia, record nearly identical and synchronous tectono-sedimentary shifts marking the Sinsk event. These resulted from an abrupt pulse of contractional supracrustal deformation on both continents during the Pararaia janeae trilobite Zone. The Sinsk event extinction was triggered by initial Ross/Delamerian supracrustal contraction along the edge of Gondwana, which caused a cascading series of geodynamic, paleoenvironmental, and biotic changes, including (i) loss of shallow marine carbonate habitats along the Gondwanan margin; (ii) tectonic transformation to extensional tectonics within the Gondwanan interior; (iii) extrusion of the Kalkarindji large igneous province; (iv) release of large volumes of volcanic gasses; and (v) rapid climatic change, including incursions of marine anoxic waters and collapse of shallow marine ecosystems."

Comment: all of this can only happen if a planet has plate tectonics. Gould said our arrival depended upon contingencies. Plate tectonics is a major one.