[meteorite-list] The COMET that killed the dinosaurs

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 22 May 2009 17:30:14 -0500
Message-ID: <66CE0345F4484C0D86D2F729B625A9DD_at_ATARIENGINE2>

Dear Doug, EP, List,

> Keller, who as a matter of fact does believe a shower
> was likely involved and allows that it could have been
> cometary and happened over a longer span of time...

Doug, while touting a series of impacts as the cause of the
K-T extinction for a few years, Keller now rejects any role
for any impact, no matter how big... Well, sometimes she
does... and sometimes not.

The latest version of Kellerism presents the "view of the
K-T mass extinction mechanism where extraterrestrial
impact had no influence on the faunal mass extinction,?
http://www.dailyprincetonian.com/2009/05/06/23652/

Keller has supported the volcanic theory since 2003:
http://www.sciencedaily.com/releases/2003/09/030926065930.htm

She continues to do so today:
"The impact had little immediate effect on the planet?s biome.
Says Keller: ?It didn?t kill the dinosaurs. In fact, it didn?t cause
much damage that we can determine from the geological record
[The Scientist]. ?We found not a single species went extinct
as a result of the Chicxulub impact,? says Keller."
http://blogs.discovermagazine.com/80beats/2009/04/29/new-study-casts-doubt-on-the-asteroid-strike-theory-of-dino-extinction/

Not a single species. Didn't cause much damage. Check.

While supporting, in some venues, the volcanic gas theory as
the sole cause, she has also said "It was, instead, a progressive
multi-event catastrophe, a concerted assault on the whole
edifice of life by a combination of massive volcanism, multiple
impacts and their associated climatic and environmental changes."
http://www.geolsoc.org.uk/gsl/site/GSL/lang/en/chicxulub

[I don't know how she explains that, in the sedimentary layers
between Deccan Trap basalt flows, there are dinosaur fossils.
So, the Traps couldn't even kill the dinos that lived right on
the same continent with them. OK. Back to Gerta's Story...]

You will note that in this statement, she assigns impact an
importance second only to the massive volcanism of the Deccan
Traps, in her more recent statement she flatly asserts that impacts
like Chicxulub don't "cause much damage." Elsewhere she has
asserted that big impacts simply have no measurable effect on the
Earth.

But then, in 2006, she suggested that global warming weakened
many species and that they were then extincted by another, bigger
and yet undiscovered impact! "What the microfossils are saying
is that Chicxulub probably aided the demise of the dinosaurs,
but so did Deccan trap volcanism's greenhouse warming effect
and finally a second huge impact that finished them off."
http://www.geosociety.org/news/pr/06-47.htm

If I had a hammer...

For those who bother to read these posts because they're
interested in impacts, this must be confusing. Shall we
bottom-line it?

Let's do that.

The debate is about ~20 inches of strata, gritty limey stuff that
is found between the level of the impact and the time of the
extinction in sites near to Chicxulub (Mexico, Texas). It's about
whether 1.) that 20 inches is dead pulverized debris from the
impact slammed across the landscape and/or deposited by one of
the biggest tidal waves in the history of the planet OR whether
2.) it's quiet sediment with traces of undisturbed lifeforms in it.

Almost everyone who studied it says it's #1. Keller says #2. The
answer depends on close examination of the material, something
both sides have done (for decades). The evidence of life or no life
is forams or no forams.

What's a foram?

Foraminifera are microscopic marine creatures with tiny stony
skeletons (just like us, only forams wear theirs on the outside).
When they die, the stone shell remains. It can persist for millions
or hundreds of millions of years. Some limestones are virtually
made out of foram skeletons.

So the tiny crystals in this limestone layer are either forams
or they're just crystals, once-living or never-living. And inorganic
crystals are hard to distinguish from organic ones except in
exceptional close and precise examination, SEM, Xray, and the
like. I suggested everybody look at the evidence in:
http://www.falw.vu/~smit/csdp/debates.htm
(not because I favor Smit but because his pictures of Keller's
samples are bigger and clearer than on the GeoSociety website).

What I see (and I mean that to emphasize my subjectivity) is
that a lot of Keller's forams are NOT forams. For example, their
"cell walls" do not have the pores of a living cell, while "real"
forams do. And likewise, some of Keller's forams ARE forams.

The problem of whether this means anything is this: even if
Keller's forams were true once-living forams, it would not prove
that they were alive when they were deposited in this strata,
since foram skeletons persist for a very long time. The "real"
forams in Keller samples could have been dead for a million
years before they got there or they could have died in place
and in peace.

No way to tell.

There are other baffles. Are the few burrows really burrows?
Has life worked this strata over (bioturbulence) or not? Even
that is not decisive. If this is impact debris, would not the
few surviving living things be scrounging through it in sheer
desperation in the weeks or months after the impact before
they starved or were poisoned by the disrupted environment?
When many creatures die, the eating is good... for a while.

No way to tell.

That it's a tense issue is because for Keller to be right, dozens
of scientists in the same field have to be wrong. Not just wrong --
incompetent. And the only way to explain Keller being wrong
is the same reason: she's incompetent. You can see why folks
would get a little snippy in this lofty debate of noble science.

Another point is this. The strata under discussion are all found
close to the impact site (Mexico, Texas). In Spain, in China, in
Africa, there is NO separation of impact layer and extinction
layer. They lay on each other as flat as a strap with no intervening
strata.

Now, IF there was a 300,000 year gap between the impact and the
extinction, wouldn't it show up EVERYWHERE in the world? Or,
at a minimum, wouldn't show up SOMEWHERE else? And, the
truth is -- it doesn't. Not anywhere. Not even in undisturbed
ocean sediment. (See: MacLeod, K.G., Whitney, D.L., Huber, B.T.,
Koeberl, C., 2007. Impact and extinction in remarkably complete
K/T boundary sections from Demerara Rise, tropical western
North Atlantic. Geol. Soc. Amer. Bull. 119 (1), 101?115.) They
were unable to find the stony corpse of even one Cretaceous
micro-organism above the impact layer in any core sample.

Not one.

Here's a summary of those results:
http://gsa.confex.com/gsa/2004AM/finalprogram/abstract_80313.htm
And here's the full paper:
http://www.univie.ac.at/geochemistry/koeberl/publikation_list/293-KT-boundary-Demerara-GSAB2007.pdf

One impact. One extinction. Simultaneous (well, geologically
anyway). Adieu, T. Rex.

That's what the evidence seems to say. Well, that's what it
says to 97% of all the researchers in the field. Or maybe
it's 99%. People who don't like the idea of impact as a process
like Keller; she plays to them. But then, those people don't
study impacts. Nasty things. And they don't know much about
them. Then, she turns around and suggests even bigger impacts.
She gets a great deal of press but very few supporters. She's
very popular among people with a "cultural" interest in science.

Now me, I take the long view. Once there were dinosaurs.
Now there are not. They all died out at about the same time,
along with the wonderful ammonites. (Who weeps for the
ammonites? You dinochauvinistes!) It doesn't exonerate
the Killer Asteroid if it took a thousand years, 100,000 years,
or a million years to kill the Dinos. Still guilty as charged.
Did they die all once? Gasp, Flop? Did it take 5000 years?
10,000 years? (There seems to be a Dead Zone about that
length.) 25,000 years (which is all that remains of Keller's
300,000 years)? And even Smit says it took 35,000 years...
So, how many years are we arguing about? Any?

What difference?

No dinos. Cryptozoologists see dinos in African lakes but it's
a sad drab world -- there are no dinos in the lake, or on the
plateau mountain of Auyan Tepui, and Conan-Doyle's dream
of a Lost World is just a dream. No dinos, just a 3212-foot-high
waterfall, the highest in the world. No pterodactyls in Illinois,
although one was spotted in 1948. No plesiosaurs in Loch Ness.
'Tho I canna be sure... No living fossils except a deep-water
fish and deep-water nautilii that kept their heads down
(or shells down).

They're gone. It was quick but probably not painless. Read
more (much more) at:
http://books.google.com/books?id=ZaIO8wl_OZIC
if you can stand to read a GoogleBook, or this one:
http://books.google.com/books?id=kAup0TOL09gC
particularly Graham Ryder's article starting on page 31.

He points out that the K-T boundary was quickly recognized
almost two centuries ago. It was quite different than other
boundaries and it was always clear that it was a sharp and
abrupt change; Darwin called it "wonderfully sudden."
Actually finding the boundary in the field was easy, even
in 1850 -- chalk overlaid with gooey clay. Thus, it is a
particularly ironic reversal that some geologists spend a
lot of time and effort to make it seem gradual when the
one thing geologists knew about it for centuries was
that it was abrupt.

EP, you asked me to calculate the impact. It's been done by
far better than I; I'll send you a list of URL's Off-List. Size?

Think Big. Then... Think Bigger.

At 170 kilometers, Chicxulub is the third biggest impact crater
surviving on the Earth's surface, being exceeded only by the 250km
Sudbury (1.85 billion years old) with twice its area and the 300km
Vredefort (2.2 billion years old) with three times its area. They're
arguing about whether there's an outer ring wall at 300 kilometers
at Chicxulub (making it as big as Vredefort, unless Vreddy had an
outer ring at 550 km...)

Think of the movie "Armageddon" without the happy ending.
The Chicxulub Fall wasn't a once-in-a-100,000,000-year accident.
It was a once-in-a-billion-year accident. Did it briefly set the
entire planet on fire? They say so... Take a good look at:
http://www.lpi.usra.edu/science/kring/epo_web/impact_cratering/enviropages/wildfires.html

It changed the World forever. "50% of all genera were extinct.
17% of all animal families were wiped out. 50% of all angiosperms
in North America alone went extinct. All of the dinosaurs save
the birds were extinct. The great marine reptiles were gone.
The pterosaurs were toast. The majority of the archosaurs and
most diapsid megafauna was swept away. The archosaur grip
on the ecologies that had lasted for 150 million years, was ended."
http://thedragonstales.blogspot.com/2009/04/kt-extinction-day-sky-fell.html

And see, he didn't even mention the ammonites either....

The same Joanne Bourgeois that thinks chevrons are not
tidal-wave-deposited (recently discussed on the List) is the
one who modeled the tsunami from Chicxulub as being
4000 to 5000 meters high.

A tidal wave three miles high. Hmmm.

At the Brazos coast in Texas where Keller's sediments are,
it was still 100+ meters. Bourgeois describes the sediments
as full of fragments and shards: fish teeth, dead wood, shell
fragments, chunks of smashed clay...
http://books.google.com/books?id=o-837rmqfPEC&pg=PA81&lpg=PA81&dq=chicxulub+tidal+wave+height&source=bl&ots=33c3ShaH_w&sig=UbLBhKQWGelvfCUxGvaM-_oyxvo&hl=en&ei=nEAWSq3qGsurtgeK2umADQ&sa=X&oi=book_result&ct=result&resnum=5

Doesn't sound like quiet sedimentation to me...

Unless, like Keller, you think the biggest impact in a billion
years had no effect whatsoever -- none. "Not a single species
went extinct as a result of the Chicxulub impact," she says.
Lady, I have a bridge in Brooklyn I want to sell you... at a very
reasonable price. Used, yes... but in excellent condition.



Sterling K. Webb
------------------------------------------------------------------------------------------------
----- Original Message -----
From: "Mexicodoug" <mexicodoug at aim.com>
To: <epgrondine at hotmail.com>; <meteorite-list at meteoritecentral.com>;
<8cba8660c696b38-b6c-795 at webmail-de18.sysops.aol.com>;
<fpspace at friends-partners.org>
Sent: Thursday, May 21, 2009 5:34 PM
Subject: Re: [meteorite-list] The COMET that killed the dinosaurs


> Hi Ed,
>
> The case we are discussing is the suspected and curious Nickel and
> Gold rich pseudometeorite or meteorite from DSDP Hole 576 recovered by
> UCLA's Cosmochemist Frank T. Kyte.
>
> Without giving my personal opinion, here are Kyte's thought on whether
> his object and the Chicxulub impactor in general is a COMET:
>
> "Analyses of a small fossil meteorite [sic] as well as the isotopic
> composition of Cr in K-T boundary sediments, point to a projectile
> similar to carbonaceous chondrite. Physical debris (i.e., Ni-rich
> spinels) in the global fallout is restricted to a single layer, and
> there is no strong evidence to support any hypothesis other than a
> single, geologically instantaneous accretionary event. This
> observation, in addition to the apparent lack of an increased flux of
> 3-He at the K-T boundary are strong arguments against a comet shower
> at 65 Ma. That the K-T meteorite [sic] is more similar to anhydrous,
> porous IDPs is also reason to suspect an asteroidal, rather than a
> cometary source for the K-T projectile."
>
> Ref: Catastrophic Events and Mass Extinctions, eds. Christian Koeberl,
> Kenneth G. MacLeod: GSA Special Paper 356 Kyte, F.T., (2002) Boulder,
> Co., "Traces of the extraterrestrial component in sediments and
> inferences for Earth's accretion history", pp. 21-38.
>
> As I said in my original post, "What this "meteorite" fragment proves
> is questionable in relation to the [K-T] debate." You would get more
> support fro
> m Dr. Keller, who as a matter of fact does believe a shower was likely
> involved and allows that it could have been cometary and happened over
> a longer span of time. Kyte, and old friend of Smit, believes the
> opposite. Each of these scientists believes this because they have
> woven a scenario on how they think it went down and these are the
> deductions from their interpretations of their theories. There is no
> absolute answers knowable yet, just a lot of foam trials on the sea.
>
> Best wishes,
> Doug
>
>
>
>
> -----Original Message-----
> From: E.P. Grondine <epgrondine at hotmail.com>
> To: mexicodoug at aim.com; meteorite-list at meteoritecentral.com;
> 8cba8660c696b38-b6c-795 at webmail-de18.sysops.aol.com;
> fpspace at friends-partners.org
> Sent: Thu, 21 May 2009 4:49 pm
> Subject: The COMET that killed the dinosaurs
>
>
> Message: 6
> Date: Thu, 21 May 2009 16:01:26 -0400
> From: Mexicodoug
> Subject: Re: [meteorite-list] K-T fossil meteorite picture
>
>
> Dear Bernd, List,
>
> Thanks for the interesting post on this curious case.
>
> So everyone can enjoy this 0.25cm "fossil" "meteorite" which Kyte
> classified as a "CV, CO, or CR carbonaceous chondrite", here is an
> original image in color:
> http://tinyurl.com/qf8u9w
>
> The "meteorite" is also described as an unclassified hematite and clay
> fragment from the core sample DSDP Hole 576 in the western North
> Pacific (32? 21.4'N, 164? 16.5'E), 1000 miles WNW of Green Island of
> the Hawaiian Islands and 1400 miles ESE of Tokyo
> ).
>
> The "meteorite" is not yet an official meteorite, relict or not (if it
> is certain it is a meteorite - unknown to me why not :-)). Kyte's
> office at UCLA has been between his colleagues Wasson and Rubin's and
> he was a co-author with them though the publications appear all prior
> to the "meteorite", so the answer to why not is probably easy to get.
>
> The extremely high gold concentration in it (which at one point I
> believe it was Koeberl said likely disqualified it as a "meteorite")
> has not been explained other than by speculation:
>
> http://tinyurl.com/qn3ssc
>
> Kyte has classified the only meteorite from the Pacific Ocean, a 2.4
> million year old mesosiderite officially named Eltanin, found 5km
> below sea level in other core samples, which he interprets to be part
> of the largest meteorite fall dropped, ever recovered on Earth. (TKW
> 1.2 Kg
> mostly in sub centimeter sized weathered fragments).
>
> Here are some very nice thin sections of the alleged relict meteorite
> from another picture in that original Nature Letter for list members'
> perusal:
> http://tinyurl.com/q4r89e
>
> Source: Letters to Nature, Frank T. Kyte sent this in originally on 2
> June 1998:
> Kyte, F.T., Nature, "A meteorite from the Cretaceous/Tertiary
> boundary", 19 November 1998, V. 396, pp. 237-239.
> http://www.nature.com/nature/journal/v396/n6708/full/396237a0.html
>
> From what I can gather, most scientists have called the K-T boundary
> fragment "meteorite" Kyte's interpretatio
> n. It should be noted that Kyte was co-author on several papers with
> Jan Smit and the two were close colleagues during the magical period
> of the early 1980's after
> Luis Alvarez did the then eye-opening K-T boundary work wit his son
> and collaborators. While the Alvarez' didn't particularly care much
> for the search for the crater, one collaborator, Jan Smit believes he
> was instrumental in the discovery of the Chicxulub crater and
> vindication
> of Alvarez' Dino extinction theory and fervently defends the work.
> Smit doesn't acknowledge challenger Princeton's Gerta Keller's group's
> interpretations which would suggest anything different on the grounds
> of Occam's Razor, in that a single impact explains everything and any
> mess is because there was turbulence afterwards shaking up everything,
> something that Keller doesn't buy as an argument stopper. Keller
> believes the extinction event is likely more complex, and has applied
> her version of chronostratigraphical study in great detail to the
> layers, and supports the possibility of multiple impacts and other
> terrestrial explanations. The latter two have become rivals and both
> (especially Smit) display emotional disdain for the other's work. They
> are both good scientists. What this "meteorite" fragment proves is
> questionable in relation to the debate. Kyte also classifies a 3.8
> billion year old impact on earth as a CV by looking at the chromium
> content of ancient sediments.
>
> Best wishes,
> Doug
>
>
>
>
>
>
> Hotmail? has ever-growing storage! Don?t worry about storage limits.
> Check it out. =
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
Received on Fri 22 May 2009 06:30:14 PM PDT