[meteorite-list] Permian-Triassic Mass Extinction Cause: 'SickEarth'

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sat Oct 21 18:54:38 2006
Message-ID: <002a01c6f563$de5eccc0$21e38c46_at_ATARIENGINE>

Hi, All,

    Ah, press-release-science! The part of such
announcements that is annoying is that there is
no room in a press release for evidence, unless
it's one piece of new-discovery evidence. None
of that here. It's a theory...

    So, as I read the (by now) many press pieces
on "Sick Earth Syndrome." I assume that there
must a good record of long-term variations and
declines in Permian oxygen levels. That's certainly
what the articles imply.

    I went a-Googling to find such a record, and --
guess what? -- there isn't one. The Permian was
an oxygen rich period mostly. There IS a record of
an "event" covering less than a half million years
which shows a thin layer with a sudden and dramatic
drop in oxygen accompanied by a dramatic marine
extinction, then a thicker layer showing a partial
recovery to still-low oxygen levels accompanied
by continuing extinction at a lesser rate, followed
a layer that begins the "oxygen boom" of the Triassic.
http://palaeo.gly.bris.ac.uk/Essays/wipeout/default.html

    This, of course, is EXACTLY what I (for example)
would expect the record of the biggest impact of the
last half-billion years to look like. I don't think that
a half-million years is very long to recover from such
an immense whack! But the palaeontologists are saying
(in effect) that it can only be an "asteroid" disaster if
the dramatic aftermath of a major impact are limited
to the eye-blink of a fruit bat in time. In geologic terms,
they're demanding we find a "discontinuity" but no
after effects.

    All these changes -- sulfate events, methane events,
dramatic climate change up, down and sideways, with
erratic atmospheric gas levels -- are perfectly explained
by an impact's effect on the Earth, particularly since
they're crammed into a short time span. The geologists
have a short time span event to blame: the flood basalts
of the Siberian Traps. Now, if they had the vaguest idea
what causes giant basalt floods, they'd be in a better
position to thumb their nose at an asteroid... But they
don't know.

    We have flood basalt events all over the Solar
System, of course, and it's pretty obvious what
caused them. And we have a mechanism for flood
basalts on Earth having been caused by impacts
(focused shock waves). And the uncommonness
of flood basalts is on the same order as the
uncommonness of a Big Whack. Then, there are
the coincidences like Chicxulub and the Deccan
Traps, and this one, too.

    In the Permian, there was only one continent,
good old Pangea, and lots of shallow ocean everywhere
else. Since the Permian event was a largely marine
extinction (94% of all marine species) and the odds on
an asteroid striking ocean are good, that too is suspicious.
Ocean crust is nowhere older than 200 million years,
so direct evidence (crater) of an ocean strike is gone.
Marenco's long-term sulfur isotope variations are
fully explicable in terms of the changes in continents
and oceans but are they great enough to "wipeout"
nearly all life?

    For 5 million years after the Event, there is no
evidence of the existence of coral reefs. Note that
this not the absence of the coral animals that build
them, but the absence of the reefs themselves. OK,
I can believe that sulfite killed the coral critters, but
explain to me how it removed all their housing as
well? I have trouble with that. Of course, the biggest
tidal wave in a billion years could sweep away their
reefs, no problem... Corals came back, obviously,
but it took them 20-30 million years. Sounds like
they had to bulding all-new housing from scratch,
doesn't it? AND, the continental configuration that
supposedly caused all this difficulty hadn't changed
one bit in the intervening time! If the continental
configuration can cause a mass extinction, why
didn't it keep on causing it? Change of heart?

    The half-million years of trouble marked by China's
Bed 25, 26, and 27 is only 30 cm thick and the layer
that shows the disaster (#25) is only 5 of those 30
centimeters, or about 80,000 years worth at uniform
rates of depositation. Of course, Bed 25 could be
from 10,000 years of depositation, too, or even only
1000 years.

    All these timescales are too short to date at
251 million years in the past. Layer 25 is full of
evidence of the Siberian Traps vulcanism, and that
surely went on a while. So, the "sharpness" of
the triggering event is not determinable. And the
iridium layer, if there even was one, would be
lost in it, as would most extraterrestrial markers
('cept the gasses in the buckeyballs?).

    I don't know if the Wilkes Land Crater will pan
out, nor Becker's Buckyballs, but if this were Las
Vegas, I would still put my money on the Permian
Whacker (knockout in the first round) over the
Siberian Gassy Wipeout as The Winnah!


Sterling K. Webb
----------------------------------------------------------
----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Friday, October 20, 2006 3:52 PM
Subject: [meteorite-list] Permian-Triassic Mass Extinction Cause:
'SickEarth'


>
> http://www.eurekalert.org/pub_releases/2006-10/uosc-mec102006.php
>
> Public release date: 20-Oct-2006
>
> Contact: Carl Marziali
> marziali_at_usc.edu
> 213-740-4751
> University of Southern California
>
> Mass extinction's cause: 'Sick Earth'
>
> USC earth scientists turn up clues to explain disappearance of 90
> percent of ancient species
>
> What really caused the largest mass extinction in Earth's history?
>
> USC earth scientists will reveal new clues at the annual meeting of the
> Geological Society of America in Philadelphia Oct. 22-25.
>
> The Permian-Triassic extinction, as it is called, is not the one that
> wiped out the dinosaurs. Nor does the cause appear to have been a
> meteorite strike, as in that famous event.
>
> The most likely explanation for the disappearance of up to 90 percent of
> species 250 million years ago, said David Bottjer, is that "the earth
> got sick."
>
> Bottjer, professor of earth sciences in the USC College of Letters, Arts
> and Sciences, leads a research group presenting several new pieces of
> the P-T extinction puzzle.
>
> Matthew Clapham, a recent Ph.D. graduate of Bottjer's laboratory, has
> found that species diversity and environmental changes were "decoupled"
> long before the extinction. Conditions on the planet were deteriorating
> long before species began to die off, Bottjer said, casting doubt on the
> meteorite strike theory.
>
> "People in the past used to think this big mass extinction was like a
> car hitting a wall," he said. Instead, Clapham's interpretation of the
> geological record shows "millions of years of environmental stress."
>
> Pedro Marenco, a doctoral student in Bottjer's lab, has been testing a
> leading theory for the P-T extinction: that a warming of the earth and a
> slowdown in ocean circulation made it harder to replace the oxygen
> sucked out of the water by marine organisms. According to the theory,
> microbes would have saturated the water with hydrogen sulfide, a highly
> toxic chemical.
>
> For a mass extinction "you really needed a good killer, and it [hydrogen
> sulfide] is really nasty stuff," Bottjer said.
>
> Marenco has measured large changes in the concentration of sulfur
> isotopes that support the hydrogen sulfide theory.
>
> ###
>
> Bottjer is slated to chair a symposium on the P-T extinction and, in a
> related presentation, to propose the Moenkopi geological formation in
> the American Southwest as a promising candidate for studying the
> extinction through analysis of the different stresses on land and sea
> during that period.
>
> Bottjer's symposium, as well as his and Marenco's presentations, take
> place Oct. 24. Clapham presents his results Oct. 22.
>
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Received on Sat 21 Oct 2006 06:54:29 PM PDT