[meteorite-list] Evidence Against Permian-Triassic Asteroid ImpactPublished

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Wed, 12 Dec 2007 18:54:21 -0600
Message-ID: <004201c83d22$b36719c0$5d22e146_at_ATARIENGINE>

Hi, List, and all Fans of Bad Asteroid Behavior,

The abstract refers to two distinct episodes of
accelerated weathering and abundance of black
carbon granules separated in time, and touts this
as "evidence" against the "impact theory," while
accepting the later of two identically described
episodes as an impact marker. So, the question is:
what, if anything, about the first such episode makes
it not proof of an impact if the second seemingly
identical episode is accepted as such?

It sounds very much like the Gerta Keller nonsense
(and it is nonsense) about an event 300,000 years
before Chixulub "proving" that a major asteroid
didn't cause an extinction, some other major asteroid
impact event did, or that it was a coincidence, or
whatever it is that Keller is trying to prove except
that she can get her name in The New York Times.

Nowhere is the magnitude of the time separation
between the two apparently identical episodes actually
given. (That's why God invented numbers.) These
"abstracts" that are too abstract to name a figure
are meaningless exercises in publicity (subliminal:
mammoth-tooth). If, for example, it were roughly
a 300,000 year gap (like Kller's imaginary gap), that
would demand an isotope dating precision of one
part in a thousand. We're good, but we're not that
good. Show me your error bars! Even a full 1%
divergence in dates by isotope dating is ridiculous.

What they are talking about is tiny shifts in the ratios
of carbon isotopes in sediments -- two sediments,
one marine and one terrestrial. The resolution of this
technique in quarter billion year old former sludge is
not good. It is good over the last 100,000 years; it's
fair over the last million years. Additionally, they are
assuming the changes in each to be synchronous
when it well known that such records are not always
in synch (the case of cave carbonates in the Western
US during the last ice age that don't match the Atlantic
or world-wide marine sediment record for O-topes);
comparing them is suspect. Just as in the above case,
the terrestrial record is that of one locale. Good, but
what about the rest of the planet?

    "The global carbon cycle, the enhanced terrestrial
weathering, the marine photic zone euxinia, the faunal
mass extinction, and the cyanobacterial expansion all
occurred as two episodes, showing a close coupling
among the ocean, the atmosphere, and the land system
at that time." That is the Gimmick -- they have to argue
that they are simultaneous for this thing to fly, because
such evidence is usually NOT "closely" coupled.

    You may well be asking your self, "What the heck is
euxinia?" and why should I care? "Euxinia" is the one-dollar
word for when the ocean bottom are stirred up and mixed
with the upper layers were photosynthetic life lives, poisoning
them with decayed material, mostly hydrogen sulfide; they
all die. The explanation for this suddenly happening and
countless trillions of tons of sediments being suddenly
stirred up to the surface of the world's oceans so violently
that it doesn't settle for a 100,000's of years is... Well, what?
Stormy weather? Do you suppose a 50 km asteroid being
dropped in the ocean might do it? OK, dumb question.
You should also realize that most oceanic sediments are
found just off the continental shelves, vulnerable to tidal
waves, especially big ones.
(Scroll down to "Green Tide.")

When's the last time you saw world-wide "photic zone
euxinia"? Well, never. Or found a record of it? Well. the
K-T event, but... For every abstract (like every expert),
there is an equal and opposite abstract (or expert). That's
Newton's First Law of Scientific BS (Bovine Signifier):
Nov., 2006: "We examine the changes to both organic
and inorganic carbon isotopes across the Permian?
Triassic boundary at two marine sections from South
China (Meishan and Shangsi) and compare these to
data from other previously published sections. Through
these analyses, we demonstrate that a decrease in delta-13C
occurred during the extinction event throughout the
Paleo-Tethys ocean. The extent and intensity of the
decrease varies by location averaging a negative shift
of ~ 5%. Several possibilities as to the cause of this
shift exist including Siberian trap volcanism, a change
in the terrestrial/marine organic carbon input to the
system, or a change in the dominant marine biota
brought about through environmental changes (such
as widespread ocean anoxia/euxinia)."

Yeah, that'll kill 96% of all Life on Earth...

That's one shift, Asteroid Fans, not two, and it's
gradual and different in different locations (subliminal:
spot terrestrial data is meaningless). And, of course,
no mention of an asteroid here, but I hear, in some far
back room, drunken geologists singing "You can Take
Yer Asteroid and Shove It." No, let's blame it on, say,
"environmental changes," that's it: Global Warming!!*
"That's where the funding is now. The hell with asteroids..."

    * The Late Permian WAS a high temperature episode,
    the hottest mean global climate in the last billion years.
    The evidence is that much of the globe's land masses
    (equatorial and lower temperate zones) were devoid
    of either plant or animal life and thoroughly "desertified."
    So, the Earth was in trouble even before...

Then, there is the assumption that an intervening sediment
was deposited at the "usual" rate as the earlier or later
sediments when there is no reason to assume that in the
midst of a cataclysmic event, anything is "usual." We know
the PT asteroid hit was either oceanic and gigantic or
coastal and gigantic -- corals disappeared for 5,000,000
years! (Add asteroid; stir vigorously.) As for intervening
sedimentary bands, what exactly would be the depositation
record of a tidal wave 5000 meters high? How many times
would it circle the planet? How many times would the oceans
withdraw from the coasts hundreds of miles and then return
to crash a thousand miles or more inland, cresting mountain
ranges along the way? Gee, could that disturb sedimentation


As to whether this "evidence" (if it's any good) proves the
absence of an impact, it would seem to me that it provides
even better evidence of TWO asteroid hits. A "big" impactor
would have to be the result of an asteroidal "breakup." Such
breakups produce, virtually by definition, multiple objects of
varying sizes. It would seem to me that a big impact can only
occur when there are a "population" of big impactors, which
means the chance of multiple hits is vastly enhanced. (It could
be that the "Permian Pounder" was the last of that huge flock
of impactors generated between 400 and 600 million years and
it took 150-200 million years to find us, but less likely. If it was,
it would be an L or LL.. Find me a piece! That'll settle it.)

As for my cavalier attitude about "proving" an huge asteroid
impact, well, it will be nice when it happens, but I don't have
"to prove it." It is as certain an event over the time scale of
100 million or 500 million years as the existence of the Moon
or the Sun. It is a necessary condition deriving from the mass
constitution of the solar system as Euclidianly certain as any
long-term event ever gets. "When" is a detail... I'm going to get
one of the bumper stickers that says: "Impacts Happen!" And
both I and the holders of that ^other^ bumper sticker are right.

As for impacts and extinctions, well, in the absence of a truly
compelling and locked-down case for a unique terrestrial cause,
it does seem to be an absurd coincidence that the two hang
out together so often. Coincidence is a poor explanation; it
lacks depth and richness, and makes you look silly, to boot.
Let's go with: "Careless finback reptile technology wantonly
increased atmospheric greenhouse gases until the oceans all
flipped over at once and poisoned them because of their
failure to adopt non-carbon-polluting transport." Yeah, that
ought to do it... That funding should be here any day now.

Sterling K. Webb
----- Original Message -----
From: "Paul" <bristolia at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Wednesday, December 12, 2007 3:21 PM
Subject: [meteorite-list] Evidence Against Permian-Triassic Asteroid

In ?December Media Highlights: Geology and GSA Today? at:
http://www.geosociety.org/news/pr/07-68.htm, there is:

Xie, S., R. D. Pancost, J. Huang, P. B. Wignall, J.
Yu, X. Tang, L. Chen, X. Huang, and X. Lai, 2007,
Changes in the global carbon cycle occurred as two
episodes during the Permian-Triassic crisis. Vol. 35,
no. 12, pp. 1083-1086.


The press release stated:

?Earth witnessed its most severe mass extinction 250
million years ago. This extinction has been thought
to be abrupt and probably caused by an extraterrestrial
impact. However, Xie et al. present several lines of
geochemical evidence from a South China section (an
optimal section to study the biotic crisis) that
indicates a two-episodic global change in association
with the ecological crisis. The global carbon cycle,
the enhanced terrestrial weathering, the marine
photic zone euxinia, the faunal mass extinction,
and the cyanobacterial expansion all occurred as two
episodes, showing a close coupling among the ocean,
the atmosphere, and the land system at that time. In
particular, Xie et al. found that the first episode
occurred before the presumed bolide impact. The
temporal sequence of these two events suggests that
the biotic crisis was a consequence of prolonged and
episodic changes in the marine and continental
systems, and argues against an extraterrestrial
impact as the main cause.?


Paul H.

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Received on Wed 12 Dec 2007 07:54:21 PM PST

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