[meteorite-list] Mercury data

From: Michael Mulgrew <mikestang_at_meteoritecentral.com>
Date: Sun, 19 Jun 2011 17:43:45 -0700
Message-ID: <BANLkTik9uPShoW+=vK=dyef2pQ6vpdfUXA_at_mail.gmail.com>

Mercury or not, whatever the Angrite parent body is/was is sure to be
interesting once it is figured out. The oxygen isotope analysis sure
points to a large, differentiated parent body. It makes me wonder
about the moons in the Jovian system. Ganymede, for example, is
larger than Mercury (currently) is; I wonder if we have any
Ganymeteorites in our collections waiting to be discovered?

Food for thought,
-Michael in so. Cal.

On Sun, Jun 19, 2011 at 3:59 PM, Sterling K. Webb
<sterling_k_webb at sbcglobal.net> wrote:
>
> Thanks, Carl. That's was what I was hoping for.
>
> There are two "Theories of Mercury" --- the old one,
> that Mercury formed from inner disk materials, all
> iron and refractories, and the new one, that Mercury
> suffered a "Giant Impact' which added its iron to the
> Mercurian core but blasted Mercury's crust off to be
> lost.
>
> Sometimes the Giant Impact Theory is interpreted
> as a much-larger Mercury that lost much of its crust
> to a series of Pretty Dam Big Impacts that contributed
> no iron but blasted Mercury's crust off to be lost just
> the same.
>
> The old "All Iron And Refractories" theory seems, at
> first glance, to be dead, but wait! there's still a heart
> beat. The Crust is not The Planet. If Mercury has been
> pasted through the ages by errant asteroids and comets
> from Out-System that have been tossed down into high
> eccentricity orbits, that crust of volatiles could be the
> accretion of 4 billion years of Jupiter's trash toss-out.
>
> There's a lot wrong with this idea. It's hard to deliver
> material to Mercury without splashing it right off into
> the grip of the Sun's powerful gravity, and it would
> take a lot of material to pave a planet miles deep.
> Perhaps the "anomalous" crust was delivered by the
> Late Bombardment?
>
> Sulfur, visible as yellow swirls, streaks and patches
> surrounding the pits that burped it, got up and
> screamed "Volatiles!" even before those scans were
> released. It's just like Io, but a lot hotter. It can't
> accumulate like it does on Io Still, if Mercury is
> still boiling out sulfur after "billions and billions"
> of years, it must have started with a LOT of volatiles.
>
> Recent images of Mercury can be found at:
> http://www.nasa.gov/mission_pages/messenger/multimedia/mercury_images_coll_archive_1.html
>
>> Maybe Mercury formed farther from the
>> Sun and migrated inwards...
>
> It's a whole new solar system. Jumpin' Jupiter
> wandering back and forth . Now, we have Migrating
> Mercury. The problem is "migrated from where?"
> Where do huge-iron-cored terrestrial planets with
> scads of volatiles form? It's really hard to think of
> any spot that provides vast amounts of both.
>
>
> Sterling K. Webb
> -------------------------------------------------------------------
> ----- Original Message ----- From: "Carl Agee" <agee at unm.edu>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Sunday, June 19, 2011 11:16 AM
> Subject: [meteorite-list] Mercury data
>
>
>> Of course it's still early days on understanding the Mercury data
>> coming back from Messenger, but I think there are a few simple things
>> that can be said about the two geochemical graphs that were part of
>> the press release. The major element graph of Al/Si versus Mg/Si
>> clearly shows that the measured Mercurian surface is similar to
>> basaltic and mantle rocks from the Earth. They plot along the Earth
>> array and look to be a bit more olivine-rich than mid-ocean ridge
>> basalts, but not as olivinerich as mantle peridotites, perhaps more
>> like Archean Earth komatiites. The measured Mercurian surface is NOT
>> delpleted in aluminum, like Martian basalts or Angrites. Also,
>> Messenger is clearly not measuring rocks like the lunar anorthositic
>> highlands. The major element that is still missing from this puzzle is
>> iron. The data do not say anything about the FeO content of the
>> Mercurian surface -- this is a pretty big deal, and until that is
>> known it will difficult to know exactly what we are looking at -- let
>> alone if there is a match for any known meteorite type.
>>
>> The potassium/thorium plot shows that Mercury is a lot like the other
>> terrestrial planets in terms of volatile element content. It seems to
>> be closest to the K/Th of Mars which is quite surprising, since Mars
>> is thought to be the most volatile rich of the rocky planets. This
>> runs counter to the idea that the inner solar system is chemically
>> zoned with volatile elements concentrated out at Mars and lower in
>> towards the Sun. But who knows? Maybe Mercury formed farther from the
>> Sun and migrated inwards.
>>
>> There was a brief mention of substantial amounts of sulfur, but no
>> data in the multimedia press release, so it would be interesting to
>> know what they mean by "substantial amounts". Also, why do they think
>> it is in the form of sulfide and not sulfate?
>>
>> See how important these missions of planetary exploration are and how
>> fragmentary our understanding is?
>>
>> Just my opinion....
>>
>> Carl Agee
>>
>> --
>> Carl B. Agee
>> Director and Curator, Institute of Meteoritics
>> Professor, Earth and Planetary Sciences
>> MSC03 2050
>> University of New Mexico
>> Albuquerque NM 87131-1126
>>
>> Tel: (505) 750-7172
>> Fax: (505) 277-3577
>> Email: agee at unm.edu
>> http://epswww.unm.edu/iom/pers/agee.html
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Received on Sun 19 Jun 2011 08:43:45 PM PDT