Geology Reference
In-Depth Information
9
8
7
6
Miller Range feldspathic lunar meteorites
0900xx,yy
34,14
34,19
34,23
36,11
36,15
36,18
70,13
70,16
70,20
75,11
75,14
75,17
090036
5
4
3
090075
2
090075
07006
090070
090034
Sc (ppm)
Figure 6.17.
Subsamples (mean mass: 34 mg each; range: 20-41 mg) of the Miller Range feldspathic lunar meteorites in Sc-Sm
space (compare with Figure 6.3). For the MIL 0900xx stones, we were allocated three different samples and analyzed four or more
subsamples of each.
samples of each stone and analyzed 3-5 subsamples of
each by INAA. For the most part, the stones are highly
feldspathic (low Sc) and poor in incompatible elements
(Figure 6.3). Two of the MIL 090075 samples, however,
contain some Sm-rich lithology, but the third overlaps in
composition with the three MIL 090070 samples and one
of the MIL 090034 samples (Figure 6.17). Despite the
differences, preliminary data of
Nishiizumi and Caffee
[2013] show that MIL090034, MIL 090070, and MIL
090075 all have similar concentrations of cosmogenic
radionuclides. Thus, we assume that MIL090034 is paired
with MIL 090070 and MIL 090075 and that the meteorite
is compositionally heterogeneous at the scale of our
sampling.
that the meteorite is heterogeneous at the scale of our
sampling (Figure 6.17). In detail, MIL 090036 shows no
compositional overlap with the other three MIL 0900xx
stones. It is significantly richer in incompatible elements
Ti, Na, Eu, and siderophile elements (Table 6.2;
Figures 6.3, 6.9, and 6.18) [
Korotev et al
., 2011]. MIL
090036 is compositionally and petrographically similar to
NWA 7022 [
Kuehner et al
., 2012] (Figure 6.18), but the
preliminary CRE data do not substantiate launch pairing
[
Nishiizumi and Caffee
, 2013].
There is no petrographic or compositional evidence to
suspect that any of the MIL 0900xx stones is paired with
either MIL 05035 (basalt) or MIL 07006 (basalt-bearing
feldspathic regolith breccia). None of the MIL 0900xx
stones contain basaltic clasts [
Liu et al
., 2011] and the tex-
ture of MIL 07006 is very different from those of any of
the MIL 0900xx stones. The preliminary CRE data
[
Nishiizumi and Caffee
, 2013] also argue that four distinct
lunar meteorites have been found at the Miller Range site.
6.5.14. Miller Range 090036
MIL 090036 is also a glassy-matrix, clast-rich, imma-
ture, feldspathic regolith breccia. Like MIL 090036/70/75,
it is dominated by clasts of impact-melt breccias. Those
in MIL 090036 are compositionally distinct, having more
sodic plagioclase and more magnesian mafic silicates
than the melt-breccia clasts in the other MIL 0900xx
stones. As with MIL 090036/70/75, we analyzed multiple
subsamples of three MIL 090036 samples. The three sub-
samples do not overlap in composition, again indicating
6.6. DISCUSSION AND SUMMARY
Lunar meteorites collected on ANSMET expeditions
cover much of the compositional range observed among
all lunar meteorites (Figure 6.4). Absent, however, are
meteorites with 7% to 12% FeO and those with very high
