from the can't-feel-the-earth-move-under-my-feet...uh-oh dept.
Major volcanic events linked to the slowing of tectonic plates:
In the past history of Earth there have been times when magma from the molten mantle has flowed out into, or over, the solid crust of the planet. In the cases where these major volcanic events have led to excessive accumulations of lava, the resulting formations have been termed Large Igneous Provinces (LIPs). Some LIPs have an aerial extent of a few million km2 and involve volumes of igneous rock totaling up to a million km3. Such phenomena clearly had major impacts on the geology, structure and natural environments where they occurred.
[...] In the new study, led by scientists in the School of Natural Sciences at Trinity College Dublin, chemical data was obtained from ancient mudstone deposits in Wales by drilling a borehole down to a depth of 1.5 km. Analysis of the chemical markers enabled the researchers to link two key events that occurred around 183 million years ago, during the Toarcian stage at the end of the Early Jurassic Period.
The team discovered that this time period coincides directly with the occurrence of the major volcanic activity that gave rise to the Karoo and Ferrar LIP's which covered parts of what are today southern Africa and Antarctica with lava. This time was also characterized by increased concentrations of greenhouse gases, by some of the most severe climatic and environmental changes ever, and by the Pliensbachian–Toarcian extinction event that affected the world's fauna and flora.
[...] "Scientists have long thought that the onset of upwelling of molten volcanic rock, or magma, from deep in Earth's interior, as mantle plumes, was the instigator of such volcanic activity but the new evidence shows that the normal rate of continental plate movement of several centimeters per year effectively prevents magma from penetrating Earth's continental crust," said Professor Micha Ruhl, who led the research team.
"It seems it is only when the speed of continental plate movement slows down to near zero that magmas from mantle plumes can effectively make their way to the surface, causing major Large Igneous Province volcanic eruptions and their associated climatic perturbations and mass extinctions."
[...] The scientists hypothesize that a slowing of continental plate movement was the critical event that enabled magma to rise to the Earth's surface and cause the major volcanic events that have punctuated Earth's history. This volcanic activity, in turn, is thought to have delivered the devastating climatic and biological upheavals that led to some of the most extreme extinctions of biological life.
Journal Reference:
Micha Ruhl, Stephen P. Hesselbo, Hugh C. Jenkyns, et al., Reduced plate motion controlled timing of Early Jurassic Karoo-Ferrar large igneous province volcanism [open], Sci Adv, 8, 36, 2022. DOI: 10.1126/sciadv.abo0866
(Score: 2) by janrinok on Friday September 16 2022, @10:50AM (1 child)
The first question that I have is are the plates slowing down again (thus leading to another extreme ecological event) or is the current extent of volcanic activity significantly unchanged? Answering such questions would require records going back much further in time than I believe we currently have, unless somebody in our community has some particular knowledge or expertise in this subject and can help me out?
(Score: 0) by Anonymous Coward on Friday September 16 2022, @10:55PM
So, what if these times slower movement happened only during super continents (wow we up to ten now) thus, very little movement. That would explain the LIP crossing South Africa and Antarctica.