Geology Reference
In-Depth Information
Moon, or basalt petrogenesis, it has become standard to
include samples of MIL 05035 or a LAP basalt along
with
Apollo
samples to increase the sample diversity [e.g.,
Rankenburg et al
., 2006, 2007;
Day et al
., 2007;
Spicuzza
et al
., 2007;
Zhang et al
., 2010;
Elardo et al
., 2012;
Paniello
et al
., 2012;
Wang et al
., 2012].
The four YAMM stones are thought to have been
launched from one crater on the Moon. The find sites for
MET 01210 and MIL 05035 are separated by 400 km,
those for Yamato 793169 and Asuka 881757 are sepa-
rated by 380 km, and the ANSMET sites are >2500 km
from the NIPR sites. These distances are all too great for
the meteorites to be terrestrially paired. Thus, it is note-
worthy that no prospective launch pairs of the four
YAMM meteorites have been found outside of Antarctica.
For the five ANSMET lunar meteorites for which the
parameters have been measured, ejection ages from the
Moon range from 40 to 275 thousand years and terres-
trial residence times range from 10 to 230 thousand years
(Figure 6.11). On the basis of lunar meteorite finds from
Oman, an average of 1.0 kg per year of lunar rocks in the
1-g to 10-kg mass range have reached the surface of the
Earth in modern times [
Korotev
, 2012]. This calculation
has not been done with the ANSMET collection, and
such a comparison might be informative.
Among the ~19,000 named meteorite stones collected
by ANSMET (through the 2011-2012 season), 0.13% are
lunar. GRA 06157, the smallest lunar meteorite stone,
was collected at a site where only 352 meteorites have
been collected. Thirteen of the named ANSMET sites
have produced 352 or more meteorites. Ten of those
have produced at least one lunar meteorite. The Queen
Alexandra Range site (3444 named stones) has yielded
two unpaired lunar meteorites and the Miller Range site
(2038) has yielded four.
The fact that launch-paired meteorites EET 87/98
(immature regolith breccia), QUE 94281 (heterogeneous
glassy- and fragmental-matrix regolith breccia), and
Yamato 79/98 (either glassy-matrix regolith breccia [
Arai
et al
., 2002;
Koeberl et al
., 1991b] or fragmental-matrix reg-
olith breccia [
Sugihara et al
., 2004]) are texturally and com-
positionally distinct from one another argues that a single
impact on the Moon can, in fact, launch different kinds
of rocks. The YAMM launch pairs are even more diverse
in that MET 01210 is a breccia and MIL 05035, Asuka
881757, and Yamato 793169 are unbrecciated basalts.
7000
All lunar meteorites
5000
ANSMET
4000
NIPR
Africa
3000
Australia
Oman
2000
Apollo 16 soil
1000
700
500
400
300
200
100
70
50
40
30
20
50
70
100
200
300400 500 00
1000
2000
3000
4000
Sr (
μ
g/g)
Figure 6.20.
Many lunar meteorites from hot deserts are significantly contaminated with Sr, Ba, and other elements as a result of
terrestrial alteration. Meteorites from Antarctica are not contaminated with these elements.
