Volcanoes Wiped Out All Forests 250 Million Years Ago

Massive volcanic eruptions wiped out the world's forests about 250 million years ago, leaving the planet teeming with wood-eating fungi, according to a new study.

The finding confirms that even hardy trees didn't survive the Permian mass extinction, one of the most devastating losses of life Earth has ever known.

Introduction: Hotspot volcanism on Earth is restricted
to relatively small areas, on the order of 100 km
in diameter, and is generally believed to result from narrow
upwellings of hot mantle material called ‘plumes’.
At first glance, hotspots appear randomly distributed.
General associations with geoid highs and divergent
plate margins have been noted [1], and hotspots tend to
occur in provinces separated by spotless areas [2]. Matyska
[3] investigated angular symmetries of hotspot distributions,
and showed that the highest maxima were
obtained with 180° rotations. Rampino and Caldeira [4]
also conducted a statistical analysis of large and small
data sets and found that more hotspots occur as nearly
antipodal pairs than would be expected from random
distributions.
The rise of antipodal plumes from the core-mantle
boundary through a convecting mantle seems unlikely,
but axial focusing of an impact’s energy by the spherical
Earth might underlie the antipodal pairing of hotspots [5,
6]. Such a focusing mechanism has been proposed to
explain seismically disrupted terrains antipodal to major
impact basins on the Moon and Mercury [7], and to explain
formation of fractured crust on Mars opposite the
Hellas basin—perhaps later exploited as a conduit for
volcanism at Alba Patera [8].

GRACE GRAVITY EVIDENCE FOR AN IMPACT BASIN IN WILKES LAND, ANTARCTICA

GRACE gravity evidence for an impact basin in Wilkes Land, Antarctica

New details on the east Antarctic gravity field from the Gravity Recovery and Climate Experiment (GRACE) mission reveal a prominent positive free-air gravity anomaly over a roughly 500-km diameter subglacial basin centered on (70°S, 120°E) in north central Wilkes Land.

This regional inverse correlation between topography and gravity is quantitatively consistent with thinned crust from a giant meteorite impact underlain by an isostatically disturbed mantle plug.

The inferred impact crater is nearly three times the size of the Chicxulub crater and presumably formed before the Cretaceous formation of the east Antarctic coast that cuts the projected ring faults. It extensively thinned and disrupted the Wilkes Land crust where the Kerguelen hot spot and Gondwana rifting developed but left the adjacent Australian block relatively undisturbed.

The micrometeorite and fossil evidence suggests that the impact may have occurred at the beginning of the greatest extinction of life on Earth at ?260 Ma when the Siberian Traps were effectively antipodal to it. Antipodal volcanism is common to large impact craters of the Moon and Mars and may also account for the antipodal relationships of essentially half of the Earth's large igneous provinces and hot spots. Thus, the impact may have triggered the “Great Dying” at the end of the Permian and contributed to the development of the hot spot that produced the Siberian Traps and now may underlie Iceland.