[meteorite-list] Acapulcoite/Lodranite Parent-body

From: al mitt <almitt_at_meteoritecentral.com>
Date: Mon, 19 Jul 2010 23:15:25 -0400
Message-ID: <020D24E237D246D88014BBBF9D23532E_at_StarmanPC>

Hi Jeff,

Here is what McSween has to say about these two classes. Distinct in
appearance but form a coherent group with continuously varying
characteristics. They share simular mineralogies, both being composed
largely of olivine and pyroxene, with minor plagioclase, iron-nickel metal,
and troilite. They have similar oxygen isotopic composition, however they
don't define a clear mass-fractionation line.

He states that Tim McCoy and colleges shown that the acapuloite-lodranite
achondites represent sesidues from varying degrees of partial melting of
chondrites, ranging from less than 1% to as great as 25%. It is thought that
the lodranite material formed deeper in the parent body, and rising melts
generated from them passed through fractures in the overlying acapulites on
the way to the surface.

An age of 4.56 billion years has been determained for the Acapulco-lodranite
parent body from percise lead isotop chronometer. Partial melting occured
shortly after accretion.

Spectra of acapulcoites are similar to those of ordinary chondrites and
lodranites have spectra similar to a variety of "S" subtype asteroids,
suggestions include S(III), S(IV), and S(V) depending on the amount of melt
extracted.

--AL Mitterling


----- Original Message -----
From: "Jeff Kuyken"
To: "Meteorite List"
Sent: Monday, July 19, 2010 7:23 AM
Subject: [meteorite-list] Acapulcoite/Lodranite Parent-body


> Hi all,
>
> Does anyone know enough about the Acapulcoite/Lodranite Parent-body to
> know what the main differences between the classifications are? Is it just
> the grain size or is there a composition difference etc too? Any paper
> references would be appreciated.
>
> Thanks,
>
> Jeff
Received on Mon 19 Jul 2010 11:15:25 PM PDT