Geology Reference
In-Depth Information
LAP Pb-Pb [1]
LAP Pb-Pb [2]
LAP Rb-Sr [3]
LAP Rb-Sr [4]
LAP Sm-Nd [3]
LAP Ar-Ar [4]
NWA 4734 Pb-Pb [2]
NWA 032 Rb-Sr [5]
NWA 032 Ar-Ar [6]
NWA 032 Ar-Ar [6]
NNL meteorites
EET 87521 Pb-Pb [7]
EET 96068 Pb-Pb [8]
QUE 94281 Pb-Pb [9]
Y-981031 Pb-Pb [9]
YQEN meteorites
Y-793169 Pb-Pb [10]
Y-793169 U-Pb [10]
Y-793169 Sm-Nd [10]
Asuka 881757 Pb-Pb [11]
Asuka 881757 Sm-Nd [11]
Asuka 881757 Rb-Sr [11]
Asuka 881757 Ar-Ar [11]
MIL 05035 Sm-Nd [12]
MIL 05035 Rb-Sr [12]
MIL 05035 Pb-Pb [13]
MIL 05035 Pb-Pb [14]
YAMM meteorites
2600
2800
3000
3200
3400
3600
3800
4000
Crystallization age (Ma)
Figure 6.8.
Crystallization ages of the basalt lithology in ANSMET basaltic lunar meteorites and comparison to lunar meteorites
from elsewhere that are likely or possible launch pairs. At least three different age groups are indicated. Symbol shapes represent
different isotopic techniques. Sources of data: [1]
Anand et al
., 2006; [2]
Wang and Hsu
, 2010; [3]
Rankenburg et al
., 2007, [4]
Nyquist
et al
., 2005; [5]
Borg et al
., 2009; [6]
Fernandes et al
., 2003; [7]
Terada et al
., 2005; [8]
Anand et al.
, 2003; [9]
Terada et al
., 2006; [10]
Torigoye-Kita et al
., 1995; [11]
Misawa et al
., 1993; [12]
Nyquist et al
., 2007; [13]
Zhang et al
., 2010; and [14]
Terada et al
., 2007).
The YQEN also group includes NWA 4884 [
Korotev et al
., 2009b], for which there are no isotopic data.
is at the low end of the range for mare basalts from the
Apollo
and
Luna
missions (Figure 6.4), suggesting that
the meteorite may contain a non-negligible proportion
of nonmare material.
Arai and Warren
[1999] suggest
5%-10%. If the proportion is even that great, then the
nonmare material is petrographically cryptic, presum-
ably because it is finer grained than the mare material.
Compositionally, the meteorite is heterogeneous and
consists of two mafic components, (1) a primitive com-
ponent with 12%-15% FeO, high
Mg'
, and low concen-
trations of incompatible elements; and (2) an evolved
component with >24% FeO, low
Mg'
, and moderate
concentrations of incompatible elements [
Lindstrom
et al
., 1999;
Korotev et al
., 2003b]. Curiously, concen-
trations of solar wind-implanted gases [
Eugster et al
.,
1996, 2000] are two to three times greater in EET 87/96
than in MAC 88105 [
Eugster et al
., 1991;
Palme et al
.,
1991], which is more obviously a regolith breccia. EET
87/96 does, however, have the lowest concentration of
Ir of the brecciated ANSMET meteorites (Figure 6.9),
indicating little input of asteroidal meteorite material.
6.5.3. MacAlpine Hills 88104 and 88105
The two MAC 88104/05 stones (Plate 68) were found
close together in the field and are indistinguishable compo-
sitionally and petrographically [
Jolliff et al
., 1991;
Lindstrom
et al
., 1991a,b;
Neal et al
., 1991]. The meteorite is a feld-
spathic regolith breccia (Figure 6.10). The bulk composi-
tion is typical of that for a feldspathic lunar meteorite
(Figs. 6.3 and 6.4), but
Mg'
is at the ferroan end of the
range (Figure 6.7). Lithic clasts are dominated by granulitic
and impact-melt breccias, but the meteorite shows a wide
variety of relict igneous clasts nearly all associated with the
ferroan-anorthositic suite of lunar plutonic rocks [
Warren
,
1990].
Cohen et al
. [2005] have dated (
40
Ar-
39
Ar) nine
clasts of feldspathic and K-poor impact-melt breccia in
MAC 88105. Ages ranged from 2.5 ± 1.5 Ga to 3.9 ±
0.1 Ga, all similar to or younger than the ubiquitous
3.8-3.9 Ga obtained for the K-rich impact-melt breccias
in the
Apollo
collection [
Haskin et al
., 1998]. The mete-
orite also contains impact glasses mainly of nonmare
origin and rare fragments of mare basalt [
Delano
, 1991;
