This work narrows it down pretty
precisely and pretty well makes the l9inkage to the Siberian Traps bullet
proof. What caused the Traps will remain
open for debate and I like to leave open the possibility of an extreme
penetration by an iron nickel meteorite.
We do have nickel associated with the upwelling.
Whatever the situation, it is
certain that a massive outflow of basalt ensured and the out gassing was large
enough to overwhelm nature’s ability to absorb CO2. It pretty well falls together and I think we
can now assume the event itself as the causation of the Permian Extinction
without any further controversy. One
really does not look for tigers when you have dead bear lying on the carcass.
It is nice to see dates tightened
up like this and welcome. It even
supports a long protracted period of activity that kept things badly suppressed
throughout.
It is also an excellent reminder
that mankind in the long term needs to provide against any such recurrence. The risk is not non zero and can be prepared
for at least through careful study to assess actual risks.
Researchers pinpoint date and rate of Earth's most extreme extinction
Results stem from largest ever examination of fossil marine species
Thursday, November 17, 2011
Charles Henderson (middle) of the University
of Calgary collects material from a
sedimentary layer in Shangsi , Sichuan
Province, China
It's well known that Earth's most severe mass extinction occurred about
250 million years ago. What's not well known is the specific time when
the extinctions occurred. A team of researchers from North America
and China
"This is the first paper to provide rates of such massive
extinction," says Dr. Charles Henderson, professor in the Department
ofGeoscience at the University
of Calgary
About 95 percent of marine life and 70 percent of terrestrial life
became extinct during what is known as the end-Permian, a time when continents
were all one land mass called Pangea. The environment ranged from desert
to lush forest. Four-limbed vertebrates were becoming diverse and among them
were primitive amphibians, reptiles and a group that would, one day, include
mammals.
Through the analysis of various types of dating techniques on
well-preserved sedimentary sections from South China to Tibet, researchers
determined that the mass extinction peaked about 252.28 million years ago
and lasted less than 200,000 years, with most of the extinction lasting about
20,000 years.
"These dates are important as it will allow us to understand the
physical and biological changes that took place," says Henderson
There is ongoing debate over whether the death of both marine and
terrestrial life coincided, as well as over kill mechanisms, which may include
rapid global warming, hypercapnia (a condition where there is too
much CO2 in the blood stream), continental aridity and massive wildfires. The
conclusion of this study says extinctions of most marine and
terrestrial life took place at the same time. And the trigger, as suggested by
these researchers and others, was the massive release of CO2 from volcanic
flows known as the Siberian traps, now found in northern Russia
Henderson's conodont research was integrated with other data
to establish the study's findings.Conodonts are extinct, soft-bodied
eel-like creatures with numerous tiny teeth that provide critical information
on hydrocarbon deposits to global extinctions.
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