Navigation Links
Microfossils challenge prevailing views of the effects of 'Snowball Earth' glaciations on life
Date:5/26/2009

(Santa Barbara, Calif.) New fossil findings discovered by scientists at UC Santa Barbara challenge prevailing views about the effects of "Snowball Earth" glaciations on life, according to an article in the June issue of the journal Nature Geoscience.

By analyzing microfossils in rocks from the bottom of the Grand Canyon, the authors have challenged the view that has been generally assumed to be correct for the widespread die-off of early life on Earth.

"Snowball Earth" is the popular term for glaciations that occurred between approximately 726 and 635 million years ago and are hypothesized to have entombed the planet in ice, explained co-author Susannah Porter, assistant professor of earth science at UCSB. It has long been noted that these glaciations are associated with a big drop in the fossil diversity, suggesting a mass die-off at this time, perhaps due to the severity of the glaciations. However, the authors of the study found evidence suggesting that this drop in diversity occurred some 16 million or more years before the glaciations. And, they offer an alternative reason for the drop.

A location called the Chuar Group in the Grand Canyon serves as "one of the premier archives of mid-Neoproterozoic time," according to the article. This time period, before Snowball Earth, is preserved as a sort of "snapshot" in the canyon walls.

The scientists found that diverse assemblages of microscopic organic-walled fossils called acritarchs, which dominate the fossil record of this time, are present in lower rocks of the Chuar Group, but are absent from higher strata. In their place, there is evidence for the bacterial blooms that, the authors hypothesize, most likely appeared because of an increase in nutrients in the surface waters. This process is known as eutrophication, and occurs today in coastal areas and lakes that receive abundant runoff from fertilizers used in farming.

"One or a few species of phytoplankton monopolizes nutrients at the expense of others," said Porter, explaining the die-off of diverse acritarchs. "In addition, the algal blooms result in high levels of organic matter production, which we see evidence of in the high organic carbon content in upper Chuar Group rocks. In fact, the organic carbon content is so high in the upper Chuar Group, oil companies were interested in the Chuar Group as a possible source of oil and natural gas." As a result of high levels of organic matter, oxygen levels in the water can become depleted, resulting in widespread "dead zones." Porter and colleagues also found evidence for extreme anoxia in association with the bacterial blooms.

In an accompanying article describing the process of discovering the microfossils, Porter described a highlight of the trip, "when we rode through the rapids and descended into 'Powell's bowels' where the oldest rocks in the Grand Canyon frame the river passage. These rocks formed deep in the Earth approximately 1.8 billion years ago, and are very different in appearance from the overlying rocks."

The scientists braved extreme sun, rattlesnakes, scorpions, and dehydration to gather their data. They traveled by foot, helicopter, and river rafts, the last of which capsized on one occasion although the samples remained intact.


'/>"/>

Contact: Gail Gallessich
gail.g@ia.ucsb.edu
805-893-7220
University of California - Santa Barbara
Source:Eurekalert  

Related biology news :

1. Microfossils disclose geologic history of eastern California
2. The challenges of avian influenza virus: Mechanism, epidemiology and control
3. Association for Molecular Pathology joins ACLU to challenge gene patents
4. SRI International receives $100,000 Grand Challenges Explorations grant
5. Winners announced in the Elsevier Grand Challenge
6. Major international study challenges notions of how genes are controlled in mammals
7. Climate change: Global risks, challenges and decisions
8. Y chromosome and surname study challenges infidelity myth
9. Phytoplankton cell membranes challenge fundamentals of biochemistry
10. Experts discuss challenges in integrative approaches to science
11. Leading research agencies announce new international competition: "The digging into data challenge"
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Microfossils challenge prevailing views of the effects of 'Snowball Earth' glaciations on life
(Date:6/2/2016)... , June 2, 2016 The Department ... has awarded the 44 million US Dollar project, for the ... Vehicle Plates including Personalization, Enrolment, and IT Infrastructure , ... in the production and implementation of Identity Management Solutions. Numerous ... however Decatur was selected for the ...
(Date:5/20/2016)... MINNEAPOLIS , May 20, 2016  VoiceIt ... technology partnership with VoicePass. By working ... user experience.  Because VoiceIt and VoicePass take slightly ... two engines increases both security and usability. ... expressed excitement about this new partnership. ...
(Date:4/28/2016)... and BANGALORE, India , April ... EdgeVerve Systems, a product subsidiary of Infosys (NYSE: ... today announced a global partnership that will provide ... to use mobile banking and payment services.      ... a key innovation area for financial services, but it also ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... June 27, 2016 , ... Newly created 4Sight ... solutions to the healthcare market. The company's primary focus is on new product ... marketing strategies that are necessary to help companies efficiently bring their products to ...
(Date:6/27/2016)... Ginkgo Bioworks , a leading organism design company ... as one of the World Economic Forum,s Technology ... companies. Ginkgo Bioworks is engineering biology to manufacture ... the nutrition, health and consumer goods sectors. The ... Fortune 500 companies to design microbes for their ...
(Date:6/24/2016)... NY (PRWEB) , ... June 24, 2016 , ... While ... machines such as the Cary 5000 and the 6000i models are higher end machines ... is the height of the spectrophotometer’s light beam from the bottom of the cuvette ...
(Date:6/23/2016)... ... 23, 2016 , ... UAS LifeSciences, one of the leading ... UP4™ Probiotics, into Target stores nationwide. The company, which has been manufacturing high ... its list of well-respected retailers. This list includes such fine stores as Whole ...
Breaking Biology Technology: