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 Multi-year submarine-canyon study challenges textbook theories about turbidity currents
12.12.2017 | Monterey Bay Aquarium Research Institute

nachricht How do megacities impact coastal seas? Searching for evidence in Chinese marginal seas
11.12.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>