Geologists confirm oxygen levels of ancient oceans

Jun 10, 2014 by Rob Enslin
Geologists confirm oxygen levels of ancient oceans
Earth's landscape, as it may have looked more than 2.5 billion years ago. Credit: Peter Sawyer, The Smithsonian Institute

(Phys.org) —Zunli Lu and Xiaoli Zhou, an assistant professor and Ph.D. student, respectively, in the Department of Earth Sciences, are part of an international team of researchers whose findings have been published by the journal Geology (Geological Society of America, 2014). Their research approach may have important implications for the study of marine ecology and global warming.

"More than 2.5 billion years ago, there was little to no in the oceans, as methane shrouded the Earth in a haze," says Lu, a member of Syracuse University's Low-Temperature Geochemistry Research Group. "Organisms practicing photosynthesis eventually started to overpower reducing chemical compounds [i.e., electron donors], and oxygen began building up in the atmosphere. This period has been called the Great Oxidation Event."

Using a novel approach called iodine geochemistry, Lu, Zhou and their colleagues have confirmed the earliest appearance of dissolved oxygen in the ocean's surface waters.

Central to their approach is iodate, a form of iodine that exists only in oxygenated waters. When iodate is detected in carbonate rocks in a marine setting, Lu and company are able to measure the elemental ratio of iodine to calcium. This measurement, known as a proxy for ocean chemistry, helps them figure out how much oxygen has dissolved in the water.

"Iodine geochemistry enables us to constrain in oceans that have produced calcium carbonate minerals and fossils," says Lu, who developed the proxy. "What we've found in ancient rock reinforces the proxy's reliability. Already, we're using the proxy to better understand the consequences of ocean deoxygenation, due to rapid ."

Explore further: Earth's breathable atmosphere a result of continents taking control of the carbon cycle

add to favorites email to friend print save as pdf

Related Stories

In hot water: Ice Age findings forecast problems

Dec 20, 2011

(PhysOrg.com) -- The first comprehensive study of changes in the oxygenation of oceans at the end of the last Ice Age (between about 10 to 20,000 years ago) has implications for the future of our oceans under global warming. ...

It's elemental: Paper celebrates discovery of iodine

Dec 06, 2011

(PhysOrg.com) -- It's not every day that an element gets to celebrate a bicentennial, and a University of Delaware professor is pleased to have been invited to the "birthday party" for iodine, which was discovered ...

Recommended for you

Stuck-in-the-mud plankton reveal ancient temperatures

9 hours ago

New research in Nature Communications showing how tiny creatures drifted across the ocean before falling to the seafloor and being fossilised has the potential to improve our understanding of past climat ...

NASA sees Mozambique Channel's new tropical storm

9 hours ago

Tropical Cyclone 15S formed in the Mozambique Channel of the Southern Indian Ocean, and the Global Precipitation Measurement or GPM core satellite gathered data on its rainfall rates.

How rain is dependent on soil moisture

9 hours ago

It rains in summer most frequently when the ground holds a lot of moisture. However, precipitation is most likely to fall in regions where the soil is comparatively dry. This is the conclusion reached by ...

ESA image: Hungarian mosaic

10 hours ago

This image of Hungary, with the political border in white, is a mosaic of 11 scans by Sentinel-1A's radar from October to December 2014.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

frostedfields
not rated yet Jun 10, 2014
These findings are illuminating; however these two authors are the second and sixth authors, respectively; let's credit the primary author - Dalton Hardisty - along with them.

This is research coming out of the University of California, Riverside (four of the seven authors are UCR faculty/alumni), and so claiming credit for Syracuse is not necessarily inaccurate but a bit misleading.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.