[meteorite-list] 300 million years later

From: W&S Schroer <schroer_at_meteoritecentral.com>
Date: Sun, 24 Oct 2010 15:37:28 +1030
Message-ID: <0181D53D4B77436B8E6A908A75FFC7B6_at_WERNER>

Article in the 'Brisbane Times':

300 million years later, an asteroid gives up its secret

October 24, 2010 - 12:05PM

A University of Queensland (UQ) researcher has found evidence of a major
asteroid impact that occurred near the Queensland-South Australia border
more than 300 million years ago.

The asteroid, which produced a shock zone at least 80km wide, could be the
second-largest asteroid ever found in Australia.

UQ geothermal energy researcher Dr Tongu Uysal discovered the asteroid
impact during his studies of the Cooper Basin, which is a large geothermal
energy resource being developed on the border between Queensland and South
Australia.

"I noticed that the quartz grains in the rock had unusual planar deformation
features that indicated either it had been exposed to extreme tectonic
pressure or a large asteroid impact," Dr Uysal said.

"The rock deformations were confirmed as being the result of an asteroid
impact through microscopic examination of the quartz crystals and further
laboratory tests.

"The results suggest that either a very large asteroid or a cluster of
asteroids landed, but we need to do further testing to verify this."

Dr Uysal said the impact of the asteroid triggered a huge explosion and
caused the ground water to boil and induce chemical and mineralogy changes
in the surrounding rocks.

"This may have resulted in the reconcentration of various heat-producing
elements which has made the Cooper Basin such a rich source of geothermal
energy today," he said.

The land surface that the asteroid hit is now buried under layers of
sedimentary rock and Dr Uysal thinks the original crater has most likely
eroded away.

He said further studies of rock samples from drill holes in the Cooper Basin
were required to more accurately map the extent of the impact area and allow
scientists to estimate the size of the asteroid.

Australia's largest recorded asteroid impact is at Woodleigh, east of Shark
Bay in Western Australia.

The Woodleigh impact structure is 120km in diameter and was produced by an
asteroid six to 12km across, about 360 million years ago.

Dr Uysal, along with Dr Andrew Glikson from the Australian National
University, will present his findings at the Australian Geothermal Energy
Conference in Adelaide from November 19.

Arcticle here: http://tiny.cc/md43h

Cheers
Werner Schroer
Received on Sun 24 Oct 2010 01:07:28 AM PDT