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

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>