Geology Reference
In-Depth Information
,20
,0
only
QUE 94201 ,20
34
35
38
46
Figure 3.11.
Images of QUE 94201 chip ,20 which was used to make four thin sections, one of which was studied by multiple
investigators over a 15-year period.
Return mission: a rock sample could be divided into sub-
portions that are subsequently divided for various
analyses [e.g.,
Beaty et al.
, 2008]. As an example of how
material has been used sparingly and efficiently by the
curators, a 2-g chip was used to make four thin sections,
one of which (,46) has been allocated six times, allowing
measurements to be made of such diverse properties as
oxidation state, mineralogy, volatile content, rare earth
element geochemistry, and clinopyroxene mineral zoning
(Figure 3.11).
to a better understanding of a wide variety of processes on
Mars such as magma genesis and subsequent surficial
processes (weathering and alteration) at the martian sur-
face [see
McSween et al
., 2014 (this volume)].
MIL 03346 was subdivided in three main stages: initial
processing (13.15 g including 5 thin sections), slab alloca-
tions (46.46 g including 49 chips and 7 thin sections), and
NE butt end allocations (32.05 g including 8 chips and 1
thin section butt). Small pieces were derived for the initial
characterization of the sample, including a 2.1-g chip
that was potted to make thin sections (Figure 3.12). Due
to the large number of individual samples requested,
band saw slabbing was considered the best way to preserve
as much of the original mass as possible for future study
and also to document the individual meteorite chips allo-
cated (Figure 3.13). After the slab was totally subdivided
and allocated (Figure 3.14), the NE butt end was sub-
divided (Figure 3.15). The total and allocated mass of the
main mass, the slab, and the NE butt end are summarized
in Table 3.2.
After the allocation of 57 thin/thick sections and 63
chips to individual researchers, much has been learned
about MIL 03346. The scientific findings from the MIL
nakhlites were summarized by
Righter and McBride
[2011]. A 447-g piece of the main mass remains for future
studies, as well as a total of ~600 g of material that has
not been allocated. Clearly, many additional studies are
possible with this much mass left.
3.3.4. MIL 03346: A Large Nakhlite (Plate 74)
The 2003-2004 ANSMET team recovered a 715-g
nakhlite from the Miller Range (MIL) region of the
Transantarctic Mountains (MIL 03346). This was the first
nakhlite found by the U.S. Antarctic meteorite program,
and after the announcement in 2004 [
Satterwhite and
Righter
, 2004], JSC received more than 50 requests for this
sample for the Fall 2004 Meteorite Working Group meet-
ing. Since then, it has been subdivided into >200 splits and
distributed to ~70 scientists around the world for study.
The 2009-2010 ANSMET team recovered three additional,
paired masses of this nakhlite: MIL 090030 (452.6 g), MIL
090032 (532.2 g), and MIL 090136 (171.0 g) [
Satterwhite
and Righter
, 2010], making the total amount of mass
1.871 kg. Given that the original find (MIL 03346) has been
heavily studied and these new masses are available, we will
present a comprehensive overview of the subdivision of the
original mass as well as the scientific findings to date.
Nakhlites are a group of eight coarse-grained clinopy-
roxene-rich rocks that contain minor amounts of olivine
and mesostasis. They are thought to represent a series of
cumulate igneous rocks from a shallow magma chamber on
Mars [
Treiman
, 2005]. Studies of these rocks have thus led
3.3.5. CR2 Chondrites: High Demand for Diverse
Materials of Broad Interest
CR2 chondrites have been steadily recovered from
Antarctica and have enabled exceptional discoveries on a
wide variety of subfields including chondrule formation,
