[meteorite-list] Martian Mineral Could Be Linked to Microbes (Stevensite)

[Ron Baalke]

http://news.anu.edu.au/2014/05/20/martian-mineral-could-be-linked-to-microbes/

Martian mineral could be linked to microbes
Australian National University
May 20, 2014
 
Scientists have discovered that the earliest living organisms on Earth 
were capable of making a mineral that may be found on Mars.

The clay-mineral stevensite has been used since ancient times and was 
used by Nubian women as a beauty treatment, but scientists had believed 
deposits could only be formed in harsh conditions like volcanic lava and 
hot alkali lakes.

Researchers led by Dr Bob Burne from the ANU Research School of Earth 
Sciences have found living microbes create an environment that allows 
stevensite to form, raising new questions about the stevensite found on 
Mars.

"It's much more likely that the stevensite on Mars is made geologically, 
from volcanic activity," Dr Burne said.

"But our finding - that stevensite can form around biological organisms 
- will encourage re-interpretation of these Martian deposits and their 
possible links to life on that planet."

Dr Burne and his colleagues from ANU, University of Western Australia 
and rock imaging company Lithicon, have found microbes can become encrusted 
by stevensite, which protects their delicate insides and provides the 
rigidity to allow them to build reef-like structures called "microbialites".

"Microbialites are the earliest large-scale evidence of life on Earth," 
Dr Burne said. "They demonstrate how microscopic organisms are able to 
join together to build enormous structures that sometimes rivalled the 
size of today's coral reefs."

He said the process still happens today in some isolated places like Shark 
Bay and Lake Clifton in Western Australia.

"Stevensite is usually assumed to require highly alkaline conditions to 
form, such as volcanic soda lakes. But our stevensite microbialites grow 
in a lake less salty than seawater and with near-neutral pH."

One of the paper's authors, Dr Penny King from ANU, is a science co-investigator 
on NASA's Mars Curiosity rover, which uncovered the presence of possible 
Martian stevensite.

The findings also have implications for how some of the world's largest 
oil reservoirs were formed.

The discovery was made using ANU-developed imaging technology licensed 
to Lithicon. The data was run on Raijin, the most powerful supercomputer 
in the Southern Hemisphere, based at the National Computational Infrastructure 
in Canberra.

The research is published in Geology.