Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Salt holds samples of ancient seas

02.11.2001


Calcium content of ancient water hints at origins of shelled life.
© Corbis


Water trapped for millions of years gives a glimpse of oceans’ turbulent past.

Drops of sea water entombed within salt crystals millions of years ago are giving researchers a glimpse of ancient oceans. The water, trapped during evaporation, reveals that the seas have seen large chemical changes during their history.

"The consensus had been that sea-water chemistry hadn’t changed that much over the past 600 million years," says geochemist Juske Horita of Oak Ridge National Laboratory, Tennessee. The trapped drops are the "first strong evidence" to the contrary, he says.



Geologist Tim Lowenstein, of the State University of New York, Binghamton, and his colleagues gathered crystals from rock salt deposits, froze them and sliced them open. Using X-rays, they probed the chemical composition of water pockets as small as 30 micrometres across - one third of the width of a human hair1.

Crystals from Australia, the Middle East and the Americas, spanning the past 550 million years, suggest that the ratio of calcium to magnesium in sea water has fluctuated by a factor of more than five.

This record needs to be read with care, cautions geologist Robert Goldstein, of the University of Kansas. Salt crystals form only in unusual environments such as lagoons. To translate the droplets into an accurate reflection of the ocean of the time requires "many, many assumptions", Goldstein says.

Despite these drawbacks, Horita believes that "it is probably the best geological record we have right now".

Drop in the ocean

The challenge now is to match the mooted changes in sea-water chemistry with the geological forces that might have caused them. Possible suspects include underwater volcanoes and earthquakes.

When sea-floor plates move apart they release calcium into the water. Lowenstein’s team found that calcium-rich sea water tended to come from periods of ocean-floor spreading.

"It’s a neat picture," says Goldstein. But it’s not complete. Minerals washed off the land by rivers also influence ocean chemistry, as does the atmosphere, he points out.

Recreating how atmosphere, Earth and ocean interacted in the past should help us predict how ocean chemistry will respond to future forces such as rising levels of greenhouse gases. But, warns Goldstein, the final story "will be a lot more complicated than we could ever have imagined".

Life also plays its part. Animals remove large amounts of calcium - a key component of shells and skeletons - from the ocean. Lowenstein’s team saw a large rise in the amount of calcium in the ocean around the time of the Cambrian Explosion.

"This is the period about 540 million years ago when the major animal groups appear in the fossil record. Rising calcium may have stimulated the origin of shelled organisms", Lowenstein speculates.

References
  1. Lowenstein, T. K. et al. Oscillation in Phanerozoic seawater chemistry: evidence from fluid inclusions. Science, 294, 1086 - 1088, (2001).

JOHN WHITFIELD | Nature News Service
Further information:
http://www.nature.com/nsu/011108/011108-1.html
http://www.nature.com/nsu/

More articles from Earth Sciences:

nachricht NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>