Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Global Extinction: Gradual Doom as Bad as Abrupt

07.02.2012
In "The Great Dying" 250 million years ago, the end came slowly

The deadliest mass extinction of all took a long time to kill 90 percent of Earth's marine life--and it killed in stages--according to a newly published report.


The geology of Griesbach Creek in the Arctic tells an ancient tale of slow extinction.
Credit: C.M. Henderson

It shows that mass extinctions need not be sudden events.

Thomas Algeo, a geologist at the University of Cincinnati, and 13 colleagues have produced a high-resolution look at the geology of a Permian-Triassic boundary section on Ellesmere Island in the Canadian Arctic.

Their analysis, published today in the Geological Society of America Bulletin, provides strong evidence that Earth's biggest mass extinction phased in over hundreds of thousands of years.

About 252 million years ago, at the end of the Permian period, Earth almost became a lifeless planet.

Around 90 percent of all living species disappeared then, in what scientists have called "The Great Dying."

Algeo and colleagues have spent much of the past decade investigating the chemical evidence buried in rocks formed during this major extinction.

The world revealed by their research is a devastated landscape, barren of vegetation and scarred by erosion from showers of acid rain, huge "dead zones" in the oceans, and runaway greenhouse warming leading to sizzling temperatures.

The evidence that Algeo and his colleagues are looking at points to massive volcanism in Siberia as a factor.

"The scientists relate this extinction to Siberian Traps volcanic eruptions, which likely first affected boreal life through toxic gas and ashes," said H. Richard Lane, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

The Siberian Traps form a large region of volcanic rock in Siberia. The massive eruptive event which formed the traps, one of the largest known volcanic events of the last 500 million years of Earth's geologic history, continued for a million years and spanned the Permian-Triassic boundary.

The term "traps" is derived from the Swedish word for stairs--trappa, or trapp--referring to the step-like hills that form the landscape of the region.

A large portion of western Siberia reveals volcanic deposits up to five kilometers (three miles) thick, covering an area equivalent to the continental United States. The lava flowed where life was most endangered, through a large coal deposit.

"The eruption released lots of methane when it burned through the coal," Algeo said. "Methane is 30 times more effective as a greenhouse gas than carbon dioxide.

"We're not sure how long the greenhouse effect lasted, but it seems to have been tens or hundreds of thousands of years."

Much of the evidence was washed into the ocean, and Algeo and his colleagues look for it among fossilized marine deposits.

Previous investigations have focused on deposits created by a now vanished ocean known as Tethys, a precursor to the Indian Ocean. Those deposits, in South China particularly, record a sudden extinction at the end of the Permian.

"In shallow marine deposits, the latest Permian mass extinction was generally abrupt," Algeo said. "Based on such observations, it has been widely inferred that the extinction was a globally synchronous event."

Recent studies are starting to challenge that view.

Algeo and co-authors focused on rock layers at West Blind Fiord on Ellesmere Island in the Canadian Arctic.

That location, at the end of the Permian, would have been much closer to the Siberian volcanoes than sites in South China.

The Canadian sedimentary rock layers are 24 meters (almost 80 feet) thick and cross the Permian-Triassic boundary, including the latest Permian mass extinction horizon.

The investigators looked at how the type of rock changed from the bottom to the top. They looked at the chemistry of the rocks and at the fossils contained in the rocks.

They discovered a total die-off of siliceous sponges about 100,000 years earlier than the marine mass extinction event recorded at Tethyan sites.

What appears to have happened, according to Algeo and his colleagues, is that the effects of early Siberian volcanic activity, such as toxic gases and ash, were confined to the northern latitudes.

Only after the eruptions were in full swing did the effects reach the tropical latitudes of the Tethys Ocean.

The research was also supported by the Canadian Natural Sciences and Engineering Research Council and the National Aeronautics and Space Administration Exobiology Program.

In addition to Algeo, co-authors of the paper are: Charles Henderson, University of Calgary; Brooks Ellwood, Louisiana State University; Harry Rowe, University of Texas at Arlington; Erika Elswick, Indiana University, Bloomington; Steven Bates and Timothy Lyons, University of California, Riverside; James Hower, University of Kentucky; Christina Smith and Barry Maynard, University of Cincinnati; Lindsay Hays and Roger Summons, Massachusetts Institute of Technology; James Fulton, Woods Hole Oceanographic Institution; and Katherine Freeman, Pennsylvania State University.

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Greg Hand, University of Cincinnati (513) 556-1822 handgl@ucmail.uc.edu
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>