ENPNewswire-August 27, 2019--UNIVERSITY OF HELSINKI: First direct evidence for a mantle plume
origin of Jurassic flood basalts in southern Africa
Known as a "mantle plume
," this narrow conduit sends hot rock to the surface.
While the older islands have disappeared below the sea as they moved away from the mantle plume
, the youngest islands, Isabela and Fernandina, are still being formed.
They were using computer simulations to see how the geology of the western United States may have evolved over the last 20 million years and found "little support for the traditional mantle plume
hypothesis," according to the (https://news.illinois.edu/view/6367/590721) University of Illinois .
A volcano forms on a tectonic plate above a mantle plume
. As the plate moves, the plume gives birth to a series of volcanoes.
Scientists have seismic evidence that the deep part of the mantle is a graveyard where long ago slabs of earth were subducted, or thrust underneath one another, creating separate regions with different chemical compositions that eventually made their way to the surface in a hot mantle plume
, or upwelling, as the core heated the rock into magma.
While geologists had studied a variety of volcanic structures across Australia, the new study -- published in the journal Nature -- is the first to suggest they were all formed by the same mantle plume
, a narrow upwelling of magma sourced deep from within the Earth's mantle near the core.
Although the relation between these magmatic provinces and igneous activity in the Baltic Sedimentary Basin area are unclear, the latter might be related alternatively to (i) mantle plume
activity or/and (ii) wrenching extension resulting from strike-slip movements along the Tornquist Zone in the west.
This current find is "the missing link between the mantle plume
and the shallow magma chamber," according to geophysicists.
The results of the spatial distribution and sizes of the seamounts, shapes and arrangements of bases, differences in the topographic tendencies in the Easter Island and Salas y Gomez Island areas, together with geochemical and seafloor ages information, support the argument that the best mechanism to explains the origin of the volcanic chains is that of the existence of a hotspot caused by a mantle plume
localized to the W of Salas y Gomez Island, probably at ~107[degrees]W.