Featured Research

from universities, journals, and other organizations

Geologists Push Back Date Basins Formed, Supporting Frozen Earth Theory

Date:
July 4, 2008
Source:
University of Florida
Summary:
Even in geology, it's not often a date gets revised by 500 million years. But geologists now say they have found strong evidence that a half-dozen major basins in India were formed a billion or more years ago, making them at least 500 million years older than commonly thought.

Even in geology, it's not often a date gets revised by 500 million years. But University of Florida geologists say they have found strong evidence that a half-dozen major basins in India were formed a billion or more years ago, making them at least 500 million years older than commonly thought.

Related Articles


The findings appear to remove one of the major obstacles to the Snowball Earth theory that a frozen Earth was once entirely covered in snow and ice -- and might even lend some weight to a controversial claim that complex life originated hundreds of million years earlier than most scientists currently believe.

"In modern geology, to revise the age of basins like this by 500 million years is pretty unique," says Joe Meert, a UF associate professor of geology.

Agreed Abhijit Basu, a professor of geological studies at Indiana University: "The required revision is enormous -- 500 million years or about 11 percent of total Earth history."

Meert is one of eight authors of a paper on the research that recently appeared in the online edition of the journal Precambrian Research.

The Purana basins -- which include the subject of the study, the Vindhyan basin -- are located south of New Delhi in the northern and central regions of India. They are slight, mostly flat depressions in the Earth's crust that span thousands of square miles. For decades, Meert said, most geologists have believed the basins formed 500 million to 700 million years ago when the Earth's crust stretched, thinned and then subsided.

Meert said that date may have originated in early radiometric dating of sediment from the basin. Radiometric dating involves estimating age based on the decay or radioactive elements. Additionally, he said, apparent fossils retrieved from the basin seemed to have originated between 500 million and 700 million years ago.

The researchers were working on an unrelated project and had no intention of re-examining the basins' age. But then a UF graduate student, Laura Gregory, dated a kimberlite retrieved from the Vindhyan basin to about 1,073 million years ago. A kimberlite is a volcanic rock that contains diamonds.

Gregory also used paleomagnetism, a technique that estimates where rocks were formed by using the orientation of their magnetic minerals. Curious about whether the kimberlite results would apply more generally to the region, fellow UF graduate student Shawn Malone compared the kimberlite's orientation to other rocks from the Vindhyan basin. To his surprise, he found the orientations were virtually identical.

As a result, the geologists expanded the investigation, using a modified chain saw to drill wine-cork-sized cores out of dozens of rocks collected from 56 sites. Their contents all also had the same or very similar magnetic orientation, Meert said.

Much of the basins are composed of sediments that cannot be dated using any method. But Meert said the sediment also contains zircon, which can be dated using laser mass spectrometry -- vaporizing tiny bits of the rocks with a laser, then analyzing their uranium and "daughter" lead contents to tease out their formation date based on rates of decay.

All the zircon the researchers tested originated 1,020 million years ago, Meert said.

The Snowball Earth theory posits that the Earth was covered in snow and ice from about 635 million to 700 million years ago. While much geological evidence has been found to support that theory worldwide, the Vindhyan and other Purana basins lacked numerous telltale signs, such as striated or scratched boulders formed when ice drags small pebbles over bedrock and boulder beds derived from glaciers known as tillites, Meert said. As a result, he said, the basins represented a prominent obstacle to the theory.

The new study removes that obstacle because it pushes back the origins of the basins to well before Snowball Earth would have occurred.

A 2007 study, conducted independently of the UF study and published in the Journal of Geology, dated rocks from another Purana basin to 1,020 million years ago, another 500-million-year revision. One of its authors was M.E. "Pat" Bickford, a professor emeritus at Syracuse University's department of earth sciences. Bickford said the revisions of the age of the Purana basins calls into question the hypothesis that they formed when the supercontinent Rodinia broke up. Rodinia is thought to have separated into the modern continents about 700 million years ago, but the revisions make the basins too old for that split, Bickford said.

The UF research could also support a Swedish paleontologist's controversial dating of multicellular creatures called Ediacarans from an older part of the basin to 1.6 billion years. But, said Meert, "Of all the implications of this research, the notion that Ediacaran-like organisms may be much older than 580 million years is probably the most speculative."


Story Source:

The above story is based on materials provided by University of Florida. Note: Materials may be edited for content and length.


Cite This Page:

University of Florida. "Geologists Push Back Date Basins Formed, Supporting Frozen Earth Theory." ScienceDaily. ScienceDaily, 4 July 2008. <www.sciencedaily.com/releases/2008/07/080703115359.htm>.
University of Florida. (2008, July 4). Geologists Push Back Date Basins Formed, Supporting Frozen Earth Theory. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2008/07/080703115359.htm
University of Florida. "Geologists Push Back Date Basins Formed, Supporting Frozen Earth Theory." ScienceDaily. www.sciencedaily.com/releases/2008/07/080703115359.htm (accessed October 30, 2014).

Share This



More Earth & Climate News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Mudslide in Sri Lanka Buries Houses

Deadly Mudslide in Sri Lanka Buries Houses

AP (Oct. 29, 2014) A mudslide triggered by monsoon rains buried scores of workers' houses at a tea plantation in central Sri Lanka on Wednesday, killing at least 10 people and leaving more than 250 missing, an official said. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Galapagos Tortoises Bounce Back, But Ecosystem Lags

Galapagos Tortoises Bounce Back, But Ecosystem Lags

Newsy (Oct. 29, 2014) The Galapagos tortoise has made a stupendous recovery from the brink of extinction to a population of more than 1,000. But it still faces threats. Video provided by Newsy
Powered by NewsLook.com
Saharan Solar Project to Power Europe

Saharan Solar Project to Power Europe

Reuters - Business Video Online (Oct. 29, 2014) A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Matt Stock reports. Video provided by Reuters
Powered by NewsLook.com
Obama: The US Will Not 'run and Hide' From Ebola

Obama: The US Will Not 'run and Hide' From Ebola

AP (Oct. 29, 2014) Surrounded by health care workers in the White House East Room, President Barack Obama said the U.S. will likely see additional Ebola cases in the weeks ahead. But he said the nation can't seal itself off in the fight against the disease. (Oct. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins