[meteorite-list] Chelyabinsk Meteorite Sheds Light on Dinosaur Extinction Mystery

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Wed, 16 Jul 2014 18:23:26 -0400
Message-ID: <CAKBPJW8ZEyHkU1DKCV0DaVa94Ne5bSpno8jsDwjLYT7XVbP-5g_at_mail.gmail.com>

This is an interesting theory. But, how does Chelyabinsk completely
rule out a carbonaceous KT impactor? Until we recover an extant
sample of the KT impactor, the question is still unanswered. Yes,
there are dark meteorites that are not carbon-rich. But how does this
fact rule out a carbonaceous (or any) impactor for the KT impact? Am
I missing something?

Best regards,

MikeG

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On 7/16/14, Ron Baalke via Meteorite-list
<meteorite-list at meteoritecentral.com> wrote:
>
>
> NEWS RELEASE FROM THE PLANETARY SCIENCE INSTITUTE
>
> FROM:
> Alan Fischer
> Public Information Officer
> Planetary Science Institute
> 520-382-0411
> 520-622-6300
> fischer at psi.edu
>
> Russian Meteorite Sheds Light on Dinosaur Extinction Mystery
>
> July 16, 2014, Tucson, Ariz. -- A long-standing debate about the source of
> the asteroid that impacted the Earth and caused the extinction of the
> dinosaurs has been put to rest thanks to the Chelyabinsk meteorite that
> disintegrated over Russia in February 2013, a new paper published in the
> journal Icarus shows.
>
> Astronomers have debated whether the dinosaur killer was linked to the
> breakup of a large asteroid forming the Baptistina Asteroid Family (BAF)
> beyond Mars, some of which ended up on Earth-crossing orbits. The asteroid
> impacting Earth is thought to have been dark and carbonaceous. The BAF
> hypothesis was bolstered by them being dark and with a spectral shape
> similar to carbonaceous meteorites.
>
> Analysis of the Chelyabinsk meteorite shows that shock produced during
> catastrophic disruption of a large asteroid can darken otherwise bright
> silicate material. Shock darkening was first reported by Dan Britt (now at
> the University of Central Florida) in the early 1990s. The Chelyabinsk
> meteorite has both bright unshocked and dark shocked material. However, the
> details of the spectra of the dark Chelyabinsk material closely reproduces
> spectral signatures seen with members of the Baptistina Asteroid Family,
> said Planetary Science Institute Research Scientist Vishnu Reddy, lead
> author of  "Chelyabinsk meteorite explains unusual spectral properties of
> Baptistina Asteroid Family that appears in Icarus.
>
> "Shock and impact melt can make bright asteroids dark, Reddy said. "In
> other words, not all dark asteroids are rich in carbon as once thought."
> The latest measurements rule out the possibility for the Baptistina family
> being the source of the K/T impactor, he added.
>
> 'The link between the K/T impacator, thought to be carbonaceous, and BAF,
> has been proved invalid," Reddy said.
>
> Chelyabinsk provided a great opportunity to see the mixture of shocked and
> unshocked material in a single meteorite, Reddy said while cautioning that
> no clear evidence exists that the Russian meteorite itself came from the
> Baptistina family.
>
> "The new finding has implications for hazards from Near-Earth Objects and
> for mining asteroids for space-based resources," Reddy said. "A potential
> target identified as primitive and rich in volatiles/organics and carbon
> based on its spectral colors could in fact be just shocked material with
> entirely different composition."
>
> PSI researchers David P. O'Brien and Lucille Le Corre were among the
> co-authors on the paper.
>
> This research work was supported by grants from NASA's Planetary Mission
> Data Analysis Program, NEOO Program and Planetary Geology and Geophysics
> Program.
>
>
> CONTACT:
> Vishnu Reddy
> Senior Scientist
> 808-342-8932
> reddy at psi.edu
>
> PSI INFORMATION:
> Mark V. Sykes
> Director
> 520-622-6300
> sykes at psi.edu
>
>
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Received on Wed 16 Jul 2014 06:23:26 PM PDT