[FPSPACE] The COMET that killed the dinosaurs

[E.P. Grondine]

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 interpretation. 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




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