[meteorite-list] NWA 011 wanted

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:14 2004
Message-ID: <3B38DA96.DBE9A2EB_at_lehrer1.rz.uni-karlsruhe.de>

Norbert Classen wrote:

> Any information on NWA 011 is appreciated as well!

Hi Norbert and List,

MAPS 35-5, 2000, A019, excerpts:

Dhofar 007 And Northwest Africa 011: Two New Eucrites Of Different Types

S.V. Afanasiev, M.A. Ivanova, A.V. Korochantsev,
N.N. Kononkova, M.A. Nazarov
Vernadsky Institute of Geochemistry and Analytical
Chemistry, Moscow 117975, Russia (nazarov_at_geokhi.ru).


Introduction:

Here we report data received by studying two new eucrites, Dhofar 007
from the Oman desert and NWA 011 from the Sahara desert. Based on
chemical, petrologic, and mineralogical analyses they are classified as
cumulate (Dhofar 007) and noncumulate (NWA 011).

Results:

A meteorite shower, 37 pieces weighing a total of 21,270 g, was found in
1999 in the Dhofar region, Oman, and a single stone of 40 g was found in
the Sahara in 1999.

Achondrite Dhofar 007 is a monomict breccia with a gabbroitic structure
consisting of subhedral grains (0.2-0.8 mm) of pyroxene and plagioclase.

Northwest Africa 011 is an unbrecciated achondrite unlike Dhofar 007,
with a metagabbroitic structure consisting of subhedral grains of
pigeonite (0.5-0.6 mm) and plagioclase (0.05-0.1 mm).

Discussion:

The data obtained for Dhofar 007 are in the range of cumulate eucrites;
the REE pattern also supports a cumulate type of this meteorite. On the
other hand, the data for NWA 011 are in the range of main group
noncumulate eucrites; the REE pattern supports a noncumulate type of
this meteorite.
Thus, these two meteorites belong to different types of eucrites and
underwent a different formation process. Dhofar 007 has a fractional
crystallization genesis like all cumulate eucrites, and NWA 011 was
formed by a partial melting of parent material with an anomalous ratio
Fe/Mg = 69 (atomic), which is different from ratios of well-known
eucrites (30-50). It might indicate more oxidizing conditions in which
the melting process happened.


Best wishes,

Bernd
Received on Tue 26 Jun 2001 02:55:18 PM PDT