[meteorite-list] Mercury data

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Mon, 20 Jun 2011 22:21:44 -0600
Message-ID: <BANLkTi=8MH8HQhzZCEoACv5zXuELkUTKnQ_at_mail.gmail.com>

Carl:

My guess is that the FeO data are not ready for primetime. As I
understand it the XPS and the GRS on Messenger both will produce data
on FeO. So I guess we will just have to wait until more information
trickles out through press releases. The good stuff will probably be
presented in a special session at some high profile meeting like AGU
or LPSC, which are months away ? perhaps a Science or Nature issue
will be coming out earlier. I think most people will not be surprised
if the Mercurian surface is low in FeO. That?s what reflectance
spectroscopy is already suggesting. I can think of a very low FeO
achondrite that is sitting in our museum ? about a ton of it! But
seriously, I think that Mercury should also have ages that are not all
~4.5 Ga, more like the range in lunar basalts, so that?s an important
thing to consider. A word of caution about the global datasets taken
from orbit: remember that so far no shergottite basalts have been seen
with Mars orbital remote sensing, the global compositions are
summations of very large areas and are not like looking at a
geologists outcrop, let alone a nice martian meteorite hand sample.

Carl

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
------------------------------------------------------------------------

On Mon, Jun 20, 2011 at 5:33 PM, <cdtucson at cox.net> wrote:
> Carl.,
> Thank you so much for this very good information. So,
> If as you say the FeO is such a big deal. Why then would they have neglected to mention it if they found it?
> Is it possible Mercury is extremely depleted in FeO?
> I mean how could they miss it if it's there?
> And if it's not there. What kind of basalt would that match?
> Thank you.
> Carl
> --
>
>
>
> "Democracy is two wolves and a lamb voting on what to have for dinner. Liberty is a well-armed lamb contesting the vote".
>
>
> ---- Carl Agee <agee at unm.edu> wrote:
>> 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 Tue 21 Jun 2011 12:21:44 AM PDT