Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mining ancient ores for clues to early life

11.12.2012
Scientists probe Canadian sulfide ore to confirm microbial activity in seawater 2.7 billion years ago

An analysis of sulfide ore deposits from one of the world's richest base-metal mines confirms that oxygen levels were extremely low on Earth 2.7 billion years ago, but also shows that microbes were actively feeding on sulfate in the ocean and influencing seawater chemistry during that geological time period.

The research, reported by a team of Canadian and U.S. scientists in Nature Geoscience, provides new insight into how ancient metal-ore deposits can be used to better understand the chemistry of the ancient oceans – and the early evolution of life.

Sulfate is the second most abundant dissolved ion in the oceans today. It comes from the "rusting" of rocks by atmospheric oxygen, which creates sulfate through chemical reactions with pyrite, the iron sulfide material known as "fool's gold."

The researchers, led by PhD student John Jamieson of the University of Ottawa and Prof. Boswell Wing of McGill, measured the "weight" of sulfur in samples of massive sulfide ore from the Kidd Creek copper-zinc mine in Timmins, Ontario, using a highly sensitive instrument known as a mass spectrometer. The weight is determined by the different amounts of isotopes of sulfur in a sample, and the abundance of different isotopes indicates how much seawater sulfate was incorporated into the massive sulfide ore that formed at the bottom of ancient oceans. That ancient ore is now found on the Earth's surface, and is particularly common in the Canadian shield.

The scientists found that much less sulfate was incorporated into the 2.7 billion-year-old ore at Kidd Creek than is incorporated into similar ore forming at the bottom of oceans today. From these measurements, the researchers were able to model how much sulfate must have been present in the ancient seawater. Their conclusion: sulfate levels were about 350 times lower than in today's ocean. Though they were extremely low, sulfate levels in the ancient ocean still supported an active global population of microbes that use sulfate to gain energy from organic carbon.

"The sulfide ore deposits that we looked at are widespread on Earth, with Canada and Quebec holding the majority of them," says Wing, an associate professor in McGill's Department of Earth and Planetary Science. "We now have a tool for probing when and where these microbes actually came into global prominence."

"Deep within a copper-zinc mine in northern Ontario that was once a volcanically active ancient seafloor may not be the most intuitive place one would think to look for clues into the conditions in which the earliest microbes thrived over 2.7 billion years ago," Jamieson adds. "However, our increasing understanding of these ancient environments and our abilities to analyze samples to a very high precision has opened the door to further our understanding of the conditions under which life evolved."

The other members of the research team were Prof. James Farquhar of the University of Maryland and Prof. Mark D. Hannington of the University of Ottawa.

The Natural Sciences and Engineering Research Council of Canada made this study possible through fellowships to Jamieson and a Discovery grant to Wing.

To access the study's abstract: http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1647.html

Chris Chipello | EurekAlert!
Further information:
http://www.mcgill.ca

More articles from Earth Sciences:

nachricht SwRI-led team’s research shows giant asteroids battered early Earth
01.08.2014 | Southwest Research Institute

nachricht NASA Sees Zombie Tropical Depression Genevieve Reborn
31.07.2014 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Anzeige

Anzeige

Event News

Counting down to FEBS-EMBO 2014 in Paris, France

29.07.2014 | Event News

9th European Wood-Based Panel Symposium 2014 – meeting point for the wood-based material branch

24.07.2014 | Event News

“Lens on Life” - Artists and Scientists Explore Cell Divison

08.07.2014 | Event News

 
Latest News

Igniting a supernova explosion

01.08.2014 | Physics and Astronomy

When Particles Fall Left and Right at the Same Time

01.08.2014 | Physics and Astronomy

Quick blood test for malaria

01.08.2014 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>