Re: KT Boundary Inquiry


" George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote in message
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"Alan Kellogg" <mythusmage@xxxxxxxxxxxxxx> wrote in message
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In article <WyY2g.117963$oL.92988@attbi_s71>,
" George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote:

"Ken Shaw" <kshaw1967@xxxxxxxxx> wrote in message
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Alan Kellogg wrote:
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" George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote:

"Alan Kellogg" <mythusmage@xxxxxxxxxxxxxx> wrote in message
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In article <KPa2g.695261$084.275927@attbi_s22>,
"George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote:

"Alan Kellogg" <mythusmage@xxxxxxxxxxxxxx> wrote in message
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In article <XS82g.695129$084.428317@attbi_s22>,
"George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote:

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George wrote:
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George wrote:
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Alan Kellogg wrote:
Where can I find up-to-date information on the
period
of
time
leading
up
to the KT Extinction Event?

Walter Alvarez's book "T. Rex and the Crater of Doom"

I believe the question was about "up-to-date
information".
Isn't
that
book
nearly ten years old?

So?

So, it is not up-to-date information. It is also not an
unbiased
view
of
the current thinking.

Seems pretty thorough to me. Can you point out significant
weak
points
in his book?

The weakest link in the book is that it is ten years old. As
such,
there
has since been tons of data collected and interpreted, a lot
of
which
questions whether an impact actually caused the dinosaurs to
go
extinct.
The date of the Yucatan impacter has been brought into
question - it
may
be
older than the K-T boundary event. That and the fact that
the
famous
irridium layer has been found right smack in the middle of
the
Deccan
traps, a fact which not only helps date the traps, but
indicates
that
the
volcanism associated with them was ongoing before during and
after
the
K-T
boundary event. In other words, a lot of data has been
collected
that
dispute the impact theory of the demise of the dinosaurs, and
that
supports
the volcanism associated with the Deccan traps and the
resulting
climate
change as a possible major cause. These are my major beefs
with
the
book.
I'm sure there are others I've overlooked.

The fact that the largest extinction level event in geologic
history,
that
of the P-T event, is not associated with an impact, but is
associated
with
the Siberian traps weakens the impact theory for the K-T
event,
and
strengthens the theory for the Deccan traps being the most
likely
cause
of
the changes which resulted in the demise of the dinosaurs and
many
other
lifeforms. Stay tuned.

George

Now, the Siberian Traps occured during major climatological
changes
caused by the formation of Pangea, thus I can't hold the Traps
entirely
responsible. Nothing so dramatic was going on when the Deccan
Traps
were
underway, except for the Chixilub impact. Thus I consider it
most
likely
that the impact was contributory to the extinction event at
the
K-T
Boundary, much as the formation of Pangea was contributory at
the
P-T
extinction event. In either event too many severe changes too
fast for
certain species to survive.

I can't say that I agree with that assessment. Data from the
nearly
complete P-T boundary stratigraphic sections located in
Greenland
appear
to
indicate severe climate changes that coincided with the
production
of
the
Siberian Traps. It has been postulated that the Siberian
volcanism
caused
a rise in global temperatures that was high enough to cause
rapid
release
of clathrates built up on the ocean floor. The sudden release
of
such
huge
quantities of methane is suggested to have resulted in a runaway
greenhouse
that caused the extinctions. In addition, the evidence suggests
that
this
happened repeatedly over an extended period of time, and very
nearly
coincided with the periodic eruptions in Siberia. That there
were
two
'great dyings' that coincide or nearly coincide with the release
of
massive
quantities of basaltic lava onto the Earth's surface certainly
does
make
a
strong case that the events (the extinctions and the production
of
prodigious amounts of lava) are linked.

George

What of the climatic changes produced by the assembly of Pangea
at
or
around the same time? As I said, contributory.

I've not seen an papers that describe climate changes resulting
from
the
coming together of the continents toform Pangea. Obviously, they
would
contribute to climate change in some way, but whether it would
beenough to
wipe out 95% of all species, I have a doubt. But then, neither
have I
seen
the data.

I don't doubt the Siberian Traps would've produced a massive
extinction
event in and of themselves, but the contemporaneous tectonic
events
surely made matters much worse.

Why? What tectonic changes could have had a more severe effect on
land and
aquatic life than the production of so much greenhouse gas, and the
resulting increase in global atmospheric and oceanic temperatures,
and
how?

George

Habitat loss; coastal becomes inland, oceans currets chang,; wind
patterns change, marshes and swamps dry up, change in humidity both
local and world wide, change in sea leves, mountain building. Enough
changes to place sufficient stress on species to push them over the
edge
towards extinction. Thus exaserpating the extinction event.

George, you are a tad too enamored of the Siberian Traps. They were,
after all, not the only act at that concert.

He is obsessed with the Deccan and Siberian traps. He went so far as
to
deny global dimming would result from an asteroid impact in a previous
go around on whether the bolide impact was the proximate cause of the
K-T extinction.

Umm, you'll have to refresh my memory on exactly when I made that
statement, Ken. But since you brought it up, you'll have to provide
some
concrete evidence that such a dimming actually occurred. Yes,
theoretically, if a large enough bolide were to strike the earth, you
could
get such dimming. The question is not whether or not that is possible,
but
whether or not dimming actually happened and caused the referred to
extinctions.

George

Can you show that dimming would not occur following such an event? We
are, after all, taking about mega tons (at least) of material being
thrown into the air. Followed by smoke from the fires.

I'll repeat: The question is not whether dimming could occur, but whether
or not it DID occur.

George


No it isn't. Not with a crater that size. It's like asking if a 120 mm tank
cannon can shoot through a paper plate. Just grounding the jets during the
scare after the Twin Towers went down reduced dimming significantly in North
America. It amounted to one degree extra difference in day and night
temperatures in some regions. Figuring out how much dimming occurred and how
long the dimming lasted after the impact will keep people busy a while.
Anyone who wants to know if it occurred and demands evidence is pretty much
asking to be walked around and by passed.


.

Relevant Pages

  • Re: KT Boundary Inquiry
    ... traps, a fact which not only helps date the traps, but indicates that ... The fact that the largest extinction level event in geologic history, ... the Siberian Traps occured during major climatological changes ... I've not seen an papers that describe climate changes resulting from the ...
    (sci.bio.paleontology)
  • Re: KT Boundary Inquiry
    ... traps, a fact which not only helps date the traps, but indicates that ... The fact that the largest extinction level event in geologic history, ... the Siberian Traps occured during major climatological changes ...
    (sci.bio.paleontology)
  • Re: KT Boundary Inquiry
    ... traps, a fact which not only helps date the traps, but indicates that ... The fact that the largest extinction level event in geologic history, ... the Siberian Traps occured during major climatological changes ... I've not seen an papers that describe climate changes resulting from the ...
    (sci.bio.paleontology)
  • Re: KT Boundary Inquiry
    ... George wrote: ... traps, a fact which not only helps date the traps, but indicates that ... The fact that the largest extinction level event in geologic history, ... the Siberian Traps occured during major climatological changes ...
    (sci.bio.paleontology)
  • Re: KT Boundary Inquiry
    ... George wrote: ... traps, a fact which not only helps date the traps, but indicates that ... The fact that the largest extinction level event in geologic history, ... the Siberian Traps occured during major climatological changes ...
    (sci.bio.paleontology)