[meteorite-list] Black Diamonds: A interesting PBS NOVA article

From: Bob WALKER <qwalkra_at_meteoritecentral.com>
Date: Mon, 13 Apr 2009 05:12:40 +1000
Message-ID: <31FFB331B43E4DC3A72F0D2B2E79AE03_at_your0a700f0aaf>

http://arxiv.org/ftp/physics/papers/0608/0608014.pdf

----- Original Message -----
From: "Fries, Marc D" <marc.d.fries at jpl.nasa.gov>
To: <meteorite-list at meteoritecentral.com>
Sent: Monday, April 13, 2009 4:57 AM
Subject: Re: [meteorite-list] Black Diamonds: A interesting PBS NOVA article


> Wish I?d seen this one when it came out; I?d have gladly written a
> rebuttal
> paper. Not quite sure how they can claim there is a "complete absence of
> a
> deep Earth fingerprint", especially since they point out the low delta-C13
> values in carbonadoes themselves. The same range of values is seen in
> reduced carbon from both terrestrial and martian igneous rocks, as other
> papers have noted. Nitrogen has been noted in mantle fluids numerous
> times
> as well and could easily be the source of the nitrogen in carbonadoes.
> I've
> never seen "planar defect lamellae" in a carbonado, which this paper
> mentions but doesn't show. Planar defects can be simply the result of
> strain while buried, and only for silicates have the criteria for
> distinguishing strain-induced lamellae from shock-derived PDF's been
> established. All of the features of carbonadoes can be explained by
> formation in a deep-Earth environment from carbonaceous fluids or gases
> with
> the caveat that it would have to be a very reducing environment. There
> are
> two comments to be made about that - 1) that very fact has been used to
> explain away the possibility that a natural reactor is the source of
> carbonadoes, and 2) it would be a rare environment, but that is consistent
> with the fact that carbonadoes have basically only been found once in
> Earth's historical record. It also only requires a casual perusal of the
> mineral record to see examples of extremes of both reducing and oxidizing
> environments in the Earth's crust.
>
> Beyond this note, I'm really too busy to get into this. Carbonadoes are
> very cool and still mysterious, but I have yet to see a convincing
> argument
> that they are extraterrestrial. I've examined a few myself and found them
> to be a marvelous oddity, but a terrestrial oddity. I certainly wouldn't
> evoke an asteroid-sized diamond impactor to explain them.
>
> Cheers,
> MDF
>
> On 4/10/09 9:28 PM, "Steve Schoner" <schoner at mybluelight.com> wrote:
>
>> Here is the first article by Stephen Haggarty and others:
>>
>> http://www.garai-research.com/research%20statement/carbonado/carbonado-infrare
>> d.htm
>>
>> Looks to be a very compelling argument.
>>
>> Steve.
>>
>> [meteorite-list] Black Diamonds: A interesting PBS NOVA article
>> Paul bristolia at yahoo.com
>> Fri Apr 10 23:15:49 EDT 2009
>>
>> * Previous message: [meteorite-list] Gamma Ray Burst caused mass
>> extinction? (With URLs to PDF Files)
>> * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
>>
>>
>> Steve Schoner wrote:
>>
>> "Here is a very interesting PBS article on carbonados.
>>
>> http://www.pbs.org/wgbh/nova/diamond/sky2.html "
>>
>> Also look at:
>>
>> Kagi, H. and S. Fukura, 2008, Infrared and Raman spectroscopic
>> observations of Central African carbonado and implications for
>> its origin. European Journal of Mineralogy. vol. 20, no. 3,
>> pp. 387-393, DOI: 10.1127/0935-1221/2008/0020-1817
>> http://eurjmin.geoscienceworld.org/cgi/content/abstract/20/3/387
>>
>> McCall, G.J.H., 2009, The carbonado diamond conundrum.
>> Earth-Science Reviews. vol. 93, no. 3-4, pp. 85&#8211;91.
>> http://dx.doi.org/10.1016/j.earscirev.2009.01.002
>>
>> Yokochi, R., D. Ohnenstetter, and Y. Sano, 2008, Intragrain
>> Variation in g13C And Nitrogen Concentration Associated
>> with Textural Heterogeneities of Carbonado. The Canadian
>> Mineralogist. vol. 46, no. 5, pp. 1283-1296, DOI:
>> 10.3749/canmin.46.5.1283
>> http://canmin.geoscienceworld.org/cgi/content/abstract/46/5/1283
>>
>> Diamonds, II: Diamond and Carbonado: Crystal Habits and Surface
>> Morphology
>> http://www.turnstone.ca/diamond2.htm
>>
>> yours,
>>
>> Paul H.
>>
>>
>>
>>
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Received on Sun 12 Apr 2009 03:12:40 PM PDT