Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study casts doubt on ’Snowball Earth’ theory

30.09.2005


Remains of photosynthesizing microbes in prehistoric rocks suggest Earth was not ice-bound



A study that applied innovative techniques to previously unexamined rock formations has turned up strong evidence on the "Slushball Earth" side of a decades-long scientific argument.

The study appears in the Sept. 29 Science Express. The lead author is Alison Olcott, a Ph.D. student of earth sciences in the USC College of Letters, Arts and Sciences.


Geologists agree that prehistoric Earth was locked in a deep freeze during Precambrian times, about 750 to 600 million years ago. They disagree over the severity of the glaciation.

"Snowball Earth" proponents, who say that Earth’s oceans were covered by thick ice, explain the survival of life by hypothesizing the existence of small warm spots, or refugia.

On the other side are supporters of a "Slushball Earth" that would have included large areas of thin ice or open ocean, particularly around the equator.

The debate has tended to revolve around the same rock samples and analytical techniques, Olcott said. So she and her team focused on a drill core of little-known black shale deposits from southeastern Brazil and applied lipid biomarker techniques to identify prehistoric organisms based on the fatty remains of their cell membranes.

The team, which included scientists from USC, Caltech, the University of Maryland and a Brazilian mining company, identified "a complex and productive microbial ecosystem," including photosynthesizing organisms that could not have existed under a thick layer of ice.

"If there was ice, it had to have been thin enough that organisms could photosynthesize below it or within it," Olcott said.

Frank Corsetti of the USC College, one of Olcott’s advisers and a co-author on the paper, said: "What she has provided is the first real evidence that substantial photosynthesis occurred in the Earth’s oceans during the extreme ice age 700 million years ago, which is a challenge for the snowball theory."

The evidence from the drill core does not prove that large parts of the ocean remained free of sheet ice during the pre-Cambrian glaciation. It is statistically unlikely but possible, Olcott said, that the drill core found one of the tiny "refugia" for marine life whose existence is allowed under the "Snowball Earth" hypothesis.

But, she said, "finding the one anomalous spot would be quite unlikely," adding that the drill core came from an extensive formation of rocks with similar characteristics.

"At what point does an enormous refugium become open ocean?" she asked.

Skeptics also may argue that the rocks do not necessarily date to a glacial era, Olcott said. But her team found evidence of glacial activity in the samples, such as dropstones (continental rocks dropped by melting glaciers into marine deposits) and glendonites (minerals that only form in near-freezing water).

Objections aside, the paper’s main contribution may be the application of new techniques to an old chestnut.

"Geologists don’t necessarily think of looking for traces of microbes left in the rocks. This is the first direct look at the ecosystem during this time period," said Olcott, who credited USC’s geobiology program, one of a handful in the country, with influencing her thinking.

"They really try to synthesize between geology and biology. It was a new way to attack the problem."

Corsetti agrees. "The climate of collaboration between geologists and biologists," he said, "is unusually good at USC … it was this way of thinking that provided the impetus for the project in the first place."

Carl Marziali | EurekAlert!
Further information:
http://www.usc.edu

More articles from Studies and Analyses:

nachricht WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf

nachricht First form of therapy for childhood dementia CLN2 developed
25.04.2018 | Universitätsklinikum Hamburg-Eppendorf

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>