Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



WATER WORLD
Sea level as a metronome of Earth's history
by Staff Writers
Geneva, Switzerland (SPX) May 30, 2017


If the variations of the sea level are known, it is possible to predict the presence of large sedimentary accumulations created by turbidites, which often contain large volumes of hydrocarbons, one of the holy grails of exploration geology.

Sedimentary layers record the history of the Earth. They contain stratigraphic cycles and patterns that precisely reveal the succession of climatic and tectonic conditions that have occurred over millennia, thereby enhancing our ability to understand and predict the evolution of our planet.

Researchers at the University of Geneva (UNIGE), Switzerland, - together with colleagues at the University of Lausanne (UNIL) and American and Spanish scientists - have been working on an analytical method that combines observing deep-water sedimentary strata and measuring in them the isotopic ratio between heavy and light carbon.

They have discovered that the cycles that punctuate these sedimentary successions are not, as one might think, due solely to the erosion of mountains that surround the basin, but are more ascribable to sea level changes. This research, which you can read in the journal Geology, paves the way for new uses of isotopic methods in exploration geology.

The area south of the Pyrenees is particularly suitable for studying sedimentary layers. Rocks are exposed over large distances, allowing researchers to undertake direct observation. Turbidites can be seen here: large sediment deposits formed in the past by underwater avalanches consisting of sand and gravel.

"We noticed that these turbidites returned periodically, about every million years. We then wondered what the reasons for this cyclicity were", explains Sebastien Castelltort, professor in the department of earth sciences in UNIGE's faculty of sciences.

The ups and downs of oceans regulate sedimentation cycles
The geologists focused their attention on Eocene sedimentary rocks (about 50 million years ago), which was particularly hot, and undertook the isotopic profiling of the sedimentary layers. "We took a sample every 10 metres," says Louis Honegger, a researcher at UNIGE, "measuring the ratio between 13C (heavy carbon stable isotope) and 12C (light carbon stable isotope). The ratio between the two tells us about the amount of organic matter, the main consumer of 12C, which is greater when the sea level is high.

The variations in the ratio helped us explore the possible link with the sea level". The research team found that the turbidite-rich intervals were associated with high 12C levels, and almost always corresponded to periods when the sea level was low. It seems that sedimentary cycles are mainly caused by the rise and fall of the sea level and not by the episodic growth of mountains.

When the sea level is high, continental margins are flooded under a layer of shallow water. Since the rivers are no longer able to flow, they begin to deposit the sediments they carry there. This is why so little material reaches the deep basins downstream. When the sea level is low, however, rivers erode their beds to lower the elevation of their mouth; they transfer their sediment directly to the continental slopes of the deep basins, creating an avalanche of sand and gravel.

Consequently, if the variations of the sea level are known, it is possible to predict the presence of large sedimentary accumulations created by turbidites, which often contain large volumes of hydrocarbons, one of the holy grails of exploration geology.

Measuring stable carbon isotopes: a new indicator of reservoir rocks
The research provides a new role for the use of carbon isotopes. "From now on, continues Castelltort, we know that by calculating the ratio between 13C and 12C sampled in similar slope deposits close to continents, we can have an indication of the sea level, which means it's possible to better predict the distribution of sedimentary rocks in our subsurface".

In addition, this measurement is relatively simple to perform and it provides accurate data - a real asset for science and mining companies. The study also highlights the importance of sea levels, which are a real metronome for the Earth's sedimentary history.

"Of course," concludes Honegger, "tectonic deformation and erosion are important factors in the formation of sedimentary layers; but they play a secondary role in the formation of turbidite accumulations, which are mainly linked to changes in the sea level".

WATER WORLD
Sequestering blue carbon through better management of coastal ecosystems
Logan UT (SPX) May 28, 2017
Focusing on the management of carbon stores within vegetated coastal habitats provides an opportunity to mitigate some aspects of global warming. Trisha Atwood from Utah State University's Watershed Sciences Department of the Quinney College of Natural Resources and the Ecology Center has collaborated with several co-authors from Australia, including lead author Peter Macreadie from Deakin Unive ... read more

Related Links
Universite de Geneve
Water News - Science, Technology and Politics


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

Comment using your Disqus, Facebook, Google or Twitter login.

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

WATER WORLD
GMV to supply Copernicus services in support to EU external action

Refugees face 'acute crisis' in cyclone-hit Bangladesh

Targeted conservation could protect more of Earth's biodiversity

Study finds Congo's miners often resort to hunting wildlife for food

WATER WORLD
A new tool for discovering nanoporous materials

Space junk could destroy satellites, hurt economies

New Zealand company partners with U.S. Army for engineered skin

New method allows real-time monitoring of irradiated materials

WATER WORLD
A 3-D look at the 2015 El Nino

Sea level as a metronome of Earth's history

Report: China plans underwater monitoring system

Bacteria may supercharge the future of wastewater treatment

WATER WORLD
NASA Discovers a New Mode of Ice Loss in Greenland

Previously, on Arctic warming

New Light on the Future of a Key Antarctic Glacier

Methane seeping from Arctic seabed may have an upside

WATER WORLD
In China, maggots finish plates, and food waste

Bordeaux pins hopes for ravaged vineyards on June bloom

Bordeaux pins hopes for ravaged vineyards on June bloom

Helping plants pump iron

WATER WORLD
Sri Lanka appeals for help as floods foul water supply

Sri Lanka deploys thousands of troops as flood toll climbs to 169

Sri Lanka deploys more troops as flood toll climbs to 180

Study explains severity of 9.2 magnitude Sumatra earthquake

WATER WORLD
Benin to invest in one of West Africa's last wildlife havens

Ivory Coast army chief meets mutineers in their barracks

Biafra's military veterans: no regrets, 50 years on

Rwanda to control presidential candidates' social media use

WATER WORLD
Researchers Identify Conductor of Brain's Neural Orchestra and Begin to Decode the Score

Fossil skeleton confirms earliest primates were tree dwellers

Springs were critical water sources for early humans in East Africa, Rutgers study finds

New hypothesis about the origin of humankind suggests oldest hominin lived in Europe




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. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. 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