Subscribe free to our newsletters via your
. 24/7 Space News .


Subscribe free to our newsletters via your




















EARLY EARTH
Ancient rocks record first evidence for photosynthesis that made oxygen
by Staff Writers
Madison WI (SPX) Oct 09, 2015


Aaron Satkoski, a scientist in the UW-Madison Geoscience Department, holds a sample sawn from a 3.23-billion-year-old rock core sample found in South Africa. The bands show different types of sediment falling to the ocean floor and solidifying into rock. The sample provides the earliest known evidence for oxygenic photosynthesis. Image courtesy David Tenenbaum/University of Wisconsin-Madison. For a larger version of this image please go here.

A new study shows that iron-bearing rocks that formed at the ocean floor 3.2 billion years ago carry unmistakable evidence of oxygen. The only logical source for that oxygen is the earliest known example of photosynthesis by living organisms, say University of Wisconsin-Madison geoscientists.

"Rock from 3.4 billion years ago showed that the ocean contained basically no free oxygen," says Clark Johnson, professor of geoscience at UW-Madison and a member of the NASA Astrobiology Institute. "Recent work has shown a small rise in oxygen at 3 billion years. The rocks we studied are 3.23 billion years old, and quite well preserved, and we believe they show definite signs for oxygen in the oceans much earlier than previous discoveries."

The most reasonable candidate for liberating the oxygen found in the iron oxide is cyanobacteria, primitive photosynthetic organisms that lived in the ancient ocean. The earliest evidence for life now dates back 3.5 billion years, so oxygenic photosynthesis could have evolved relatively soon after life itself.

Until recently, the conventional wisdom in geology held that oxygen was rare until the "great oxygenation event," 2.4 to 2.2 billion years ago.

The rocks under study, called jasper, made of iron oxide and quartz, show regular striations caused by composition changes in the sediment that formed them. To detect oxygen, the UW-Madison scientists measured iron isotopes with a sophisticated mass spectrometer, hoping to determine how much oxygen was needed to form the iron oxides.

"Iron oxides contained in the fine-grained, deep sediment that formed below the level of wave disturbance formed in the water with very little oxygen," says first author Aaron Satkoski, an assistant scientist in the Geoscience Department. But the grainier rock that formed from shallow, wave-stirred sediment looks rusty, and contains iron oxide that required much more oxygen to form.

The visual evidence was supported by measurements of iron isotopes, Satkoski said. The samples, provided by University of Johannesburg collaborator Nicolas Beukes, were native to a geologically stable region in eastern South Africa.

Because the samples came from a single drill core, the scientists cannot prove that photosynthesis was widespread at the time, but once it evolved, it probably spread. "There was evolutionary pressure to develop oxygenic photosynthesis," says Johnson. "Once you make cellular machinery that is complicated enough to do that, your energy supply is inexhaustible. You only need sun, water and carbon dioxide to live."

Other organisms developed forms of photosynthesis that did not liberate oxygen, but they relied on minerals dissolved in hot groundwater - a far less abundant source than ocean water, Johnson adds. And although oxygen was definitely present in the shallow ocean 3.2 billion years ago, the concentration was only estimated at about 0.1 percent of that found in today's oceans.

Confirmation of the iron results came from studies of uranium and its decay products in the samples, says co-author Brian Beard, a senior scientist at UW-Madison. "Uranium is only soluble in the oxidized form, so the uranium in the sediment had to contain oxygen when the rock solidified."

Measurements of lead formed from the radioactive decay of uranium showed that the uranium entered the rock sample 3.2 billion years ago. "This was an independent check that the uranium wasn't added recently. It's as old as the rock; it's original material," Beard says.

"We are trying to define the age when oxygenic photosynthesis by bacteria started happening," he says. "Cyanobacteria could live in shallow water, doing photosynthesis, generating oxygen, but oxygen was not necessarily in the atmosphere or the deep ocean."

However, photosynthesis was a nifty trick, and sooner or later it started to spread, Johnson says. "Once life gets oxygenic photosynthesis, the sky is the limit. There is no reason to expect that it would not go everywhere."

The study was funded by NASA and published in Earth and Planetary Science Letters.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of Wisconsin-Madison
Explore The Early Earth at TerraDaily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
EARLY EARTH
Stability of surviving communities increases following mass extinction
Washington DC (SPX) Oct 07, 2015
By using fossil data, researchers have found that the structure of ecological communities leading up to the Permian-Triassic Extinction, one of the largest drivers of biodiversity loss in history, is a key predictor of the ecological communities that would demonstrate stability through the event. As we are confronted with the reality of modern day mass extinction, identifying factors that ... read more


EARLY EARTH
Lunar Pox

Space startup confirms plans for robotic moon landings

Asteroids found to be the moon's main 'water supply'

Russian scientist hope to get rocket fuel, water, oxygen from Lunar ice

EARLY EARTH
MRO imagery reveals Red Planet's stressed substrate

Geology Award Going to Mars Landing Site Expert at JPL

Terraforming the Red Planet: Nuclear Blasts Could Warm Mars for Humans?

NASA Lays the Groundwork for Homesteading in Space

EARLY EARTH
Selected NASA Discovery Missions Include Three With PSI Ties

NASA Selects Investigations for Future Key Planetary Mission

Chinese herbal expert among Nobel medicine prize winners

Down to Earth and walking the line

EARLY EARTH
Exhibition on "father of Chinese rocketry" opens in U.S.

The First Meeting of the U.S.-China Space Dialogue

China's new carrier rocket succeeds in 1st trip

China launches new type of carrier rocket: state media

EARLY EARTH
Meet the International Docking Adapter

NASA extends Boeing contract for International Space Station

Russian launches cargo spaceship to the ISS

Successful re-entry of H-II Transfer Vehicle Kounotori5

EARLY EARTH
Arianespace signs ARSAT to launch a new satellite for Argentina

Ariane 5 orbits Sky Muster and ARSAT-2

A satellite launcher for the Middle East

45th Space Wing supports ULA's 100th launch

EARLY EARTH
The Most Stable Source of Light in the World

Earth-class planets likely have protective magnetic fields, aiding life

Stellar atmosphere can be used to predict the composition of rocky exoplanets

Watching an exoplanet in motion around a distant star

EARLY EARTH
Caution: Shrinks when warm

Flipping molecular attachments amps up activity of CO2 catalyst

New system allows heightened purity of a metal binding compound

Redefining temperature with precision lasers




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News








The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement