[meteorite-list] 300 million years later

[W&S Schroer]

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