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Researchers at the University of Kansas believe evidence for these uplifts lie in the increased amounts of an element found in the continental crust that they've subsequently detected in marine fossils whenever mass extinctions have occurred.
The fact that the element, strontium-87, is suddenly appearing in the oceans means that there must have been sudden huge tectonic movements that the researchers believe played havoc with marine life.
Adrian Melott, a Professor of Physics and Astronomy at the University of Kansas , said: 'Strontium-87 is produced by radioactive decay of another element, rubidium, which is common in igneous rocks in continental crust.
'So, when a lot of this type of rock erodes, a lot more Sr-87 is dumped into the ocean, and its fraction rises compared with another strontium isotope, Sr-86.'
An uplifting of the continents, Melott explains, is the most likely explanation for this type of massive erosion event.
'Continental uplift increases erosion in several ways,' he said. 'First, it pushes the continental basement rocks containing rubidium up to where they are exposed to erosive forces. Uplift also creates highlands and mountains where glaciers and freeze-thaw cycles erode rock.
'The steep slopes cause faster water flow in streams and sheet-wash from rains, which strips off the soil and exposes bedrock. Uplift also elevates the deeper-seated igneous rocks where the Sr-87 is sequestered, permitting it to be exposed, eroded, and put into the ocean.'
The massive continental uplift suggested by the strontium data would also reduce sea depth along the continental shelf where most sea animals live.
That loss of habitat due to shallow water, Melott and collaborators say, could be the reason for the periodic mass extinctions and periodic decline in diversity found in the marine fossil record.
'What we're seeing could be evidence of a "pulse of the earth" phenomenon,' Melott said. 'There are some theoretical works which suggest that convection of mantle plumes, rather like a lava lamp, should be coordinated in periodic waves.'
The result of this convection deep inside the Earth could be a rhythmic throbbing - almost like a cartoon thumb smacked with a hammer - that pushes the continents up and down.
Melott's data suggest that such pulses likely affected the North American continent. The same phenomenon may have affected other continents as well, but more research would be needed to show that, he says.
Results of the study will be published in the March issue of The Journal of Geology.
the rest of us theorize.
Seems like core heating to me. Would produce what we see. As to what is doing the core heating, well, could be an influx of neutrinos. Could be as simple as filling a capacitor like the Milky Way and we at E may be the edge where the capacitor experiences overload and discharges as a non-locality way over there at the center of the MW, the AGN. I note G1.9 is antimatter visiting us periodically by piercing the ORT shell and receiving a repulse to sling itself back out and toward its opposite matter pole. This visitor is responsible for the compression of the heliosphere, and subsequent rebounding of same when it departs. In the past 5,000 y cycles it has meant catastrophe due to its greater energy form, but now in its degraded neutron bitsy form it cannot compress to Mercury, merely to Venus. We are saved due to weakness. But we now deal with greater neutrino input.