Another Dinosaur Extinction Theory: Mantle Plume/Volcanic Eruption

[Richard W Travsky <rtravsky@uwyo.edu>]

http://www.cf.ac.uk/news/releases/0309/030911.html

The extinction of the dinosaurs - thought to be caused by an asteroid
impact some 65 million years ago - was more likely to have been caused by
a mantle plume - a huge volcanic eruption from deep within the earths
mantle, the region between the crust and the core of the earth. This
theory, already supported by a significant body of geologists and
palaeontologists, is strengthened by new evidence to be presented at an
international conference at Cardiff University on 11-12 September.

Research by an American earth scientist, Professor Gerta Keller and her
team, suggests that a similar eruption under the Indian Ocean several
million years before the extinction of the dinosaurs had a similarly
devastating impact on the environment. However, at this earlier time there
is no evidence of any asteroid impact.

Her findings are based on analysis of microfossil assemblages, which were
found inside cores that had been drilled deep into sediments on the ocean
floor.

The eruptions that were responsible for these two extinction events were
as a result of mantle plumes - a phenomenon caused by rising hot mantle
from deep within the earth. Likened to the actions of a lava lamp, the
mantles heat causes it to rise and mushroom out; it then flattens causing
the mantle to melt and erupt magma over the earths surface and across an
area of some 1,000 kilometres diameter. These eruptions last between one
and two million years and more than one million cubic kilometres of lava
can be erupted in that time. 
...