[meteorite-list] 3.5 Billion-Year-Old Bacterial Ecosystems Found In Western Australia

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 12 Nov 2013 10:50:33 -0800 (PST)
Message-ID: <201311121850.rACIoX7Z021070_at_zagami.jpl.nasa.gov>

http://www.news.uwa.edu.au/201311116238/research/pilbara-home-35-billion-year-old-bacterial-ecosystems

Pilbara home to 3.5 billion-year-old bacterial ecosystems
The University of Western Australia
November 11, 2013
 
Evidence of complex microbial ecosystems dating back almost 3.5 billion
years has been found in Western Australia's Pilbara region by an international
team including UWA Research Assistant Professor David Wacey.

The research, published this week in the journal Astrobiology has revealed
the well-preserved remnants of a complex ecosystem in a 3.5 billion-year-old
sedimentary rock sequence.

Professor Wacey said identifying and reconstructing Earth's earliest biosphere
was challenging because the oldest sedimentary rocks were not only rare,
but also almost always changed by hydrothermal and tectonic activity.

"The Pilbara region of Western Australia is one of the rare geological
regions that provides insight into the early evolution of life on Earth,"
he said.

"Mound-like deposits created by ancient bacteria, called stromatolites,
and microfossils of bacteria have previously been discovered in this region.
 However, a phenomenon called microbially induced sedimentary structures,
or MISS, had not previously been seen in rocks of this great age."

MISS were created by microbial mats as the microbial communities responded
to changes in physical sediment dynamics, Professor Wacey said.

"A common example would be the binding together of sediment grains by
microbes to prevent their erosion by water currents," he said. "The significance
of MISS is that they not only demonstrate the presence of life, but also
the presence of whole microbial ecosystems that could co-ordinate with
one another to respond to changes in their environment."

Professor Wacey, based at the ARC Centre of Excellence for Core to Crust
Fluid Systems, the Centre for Microscopy, Characterisation and Analysis,
and the Centre for Exploration Targeting, worked with US colleagues Nora
Noffke and Daniel Christian of Old Dominion University, and Bob Hazen
of the Carnegie Institute Washington.

The team described the various MISS from the ancient coastal flats preserved
in the Dresser Formation and found close similarities in both form and
preservation style to MISS in younger rocks.

Associate Professor Noffke, lead author of the paper, said the research
extended the geological record of MISS by almost 300 million years and
showed that complex mat-forming microbial communities likely existed almost
3.5 billion years ago.

MISS are among the targets of Mars rovers, which search for similar biological
signals on that planet's surface. Hence, the team's findings could be
significant for studies of life elsewhere in our solar system.

Media references

Assistant Professor David Wacey (Centre for Microscopy, Characterisation
and Analysis) (+61 8) 6488 8064
UWA Public Affairs Media Team (+61 8) 6488 7977 / (+61 4) 32 637 716
Received on Tue 12 Nov 2013 01:50:33 PM PST