There is compositional, petrographic, and cosmic-ray-exposure evidence that many of the basaltic lunar meteorite stones are related to each other, that is, that they are paired. Some are paired in the conventional sense - they are different fragments with different names of a single meteoroid. Others appear to be from different meteoroids that were ejected from the Moon by a common impact. Such meteorites are said to be "launch paired" or "source-crater paired." Launch pairing cannot be proved with certainty, but we assume that meteorites that are (1) found too far apart on Earth to be terrestrially paired but that (2) are compositionally and mineralogically similar and (3) were ejected from the Moon at the same time are probably launch paired (e.g., Nishiizumi et al. 2006).

We present some of the compositional evidence for pairing here. For this discussion, we include all meteorite stones with >12% FeO as "basaltic."

Likely Pairings Among Basaltic Lunar Meteorites
terrestrial pairings (one meteoroid, two or more stones)
	EET 87521 and EET 96008
	LAP 02205, LAP 02224, LAP 02226, LAP 02436, LAP 03632, and LAP 04841
	NWA 032 and NWA 479
	NWA 773, NWA 2700, NWA 2727, NWA 2977, NWA 3160, and NWA 3333
	Yamato 793274 and Yamato 981031
launch pairings (one impact on Moon, two or more meteoroids)
YAMM	Asuka 881757, Yamato 793169, MIL 05035, and MET 01210
YQE	Yamato 793274/981031, QUE 94281, and EET 87521/96008
NNL	LAP 0xxxx and NWA 4734, and possibly NWA 032/479

Symbol key for non-NWA-773-clan basaltic lunar meteorite stones

The plot above is a complicated plot that only a trace-element geochemist geochemist could love!

In basalts, scandium (Sc) is carried mainly by pyroxene and cobalt (Co) by olivine. The NWA 773 stones, particularly the olivine cumulate lithology (green symbols), have low Sc/Co because they are rich in olivine. The YAMM stones (below), with little or no olivine, have high Sc/Co.

The NWA 733 basaltic magma apparently derived from a mantle source that was particularly depleted in plagioclase. As a consequence, all the stones of the NWA 733 clan are depleted in elements that are carried mainly by plagioclase - sodium (see FeO-Na₂O plot below), strontium, and europium (Eu). The NWA 733 stones have high Sm/Eu because Eu is low, not because samarium (Sm) is high (see FeO-Sm plot below; also; Jolliff et al., 2003).

In the plots presented here, each geometric symbol represents a small (20-30 mg) subsample from one of the NWA-773 clan of lunar meteorite stones. The overlap of the basalt, breccia, and cumulate lithologies among the different stones and mutual difference of all the NWA-773-clan samples from other basaltic lunar meteorites is one argument that NWA 773, 2700, 2727, 2977, 3160, and 3333 are all paired, despite the lithologic (rock type) diversity among the stones. The letters and numbers each represent the other basaltic lunar meteorite stones or, in the case of Dhofar 287 and NEA 003, the basalt or breccia lithology (average of all our data for each).

The plots show several things:

NNL meteorites 1. The 6 LAP basalt stones [symbols 1-6], which are mutually paired (all from one meteoroid), are indistinguishable from each other in composition. NWA 032 and NWA 479 [W and w], which are paired with each other, are also mutually indistinguishable. Meteorite NWA 032/479 is similar to meteorite LAP. The two meteorites are probably launch paired (Ziegler et al., 2005; see update on geochemical details here) - they are pieces of two different rocks ejected from the Moon by a single impact. One landed in Antarctica, the other in northwestern Africa.

NNL meteorites 2. Symbol T represents another NWA stone that doesn't have a name. It is not identical in composition to either NEA 032/479 or LAP, but it is similar to both. It may be either paired with NWA 032/479 or launch paired with NWA 032/479 and LAP. We don't understand yet why it is anomalously rich in sodium (Na₂O, below), but we analyzed only a small sample (40 mg) of the meteorite that may not be representative.

YQE meteorites. Yamato 793274 and Yamato 981032 [X and x] are paired stones. EET 87521 and EET 96008 [symbols C and c] are paired stones. It is likely that these two meteorites along with QUE 94281 [Q] - the YQE meteorites - are mutually launch paired (Arai & Warren, 1999; Korotev et al., 2003). All are breccias containing some highlands material. The variation in concentrations, for example, of Fe and Sc (below) among the stones reflects variation in the ratio of mare basalt and anorthosite.

YAMM meteorites. Asuka 881757 [A] and Yamato 793169 [Y] have long been considered to be launch paired (Warren & Kallemeyn, 1993; Thalmann et al., 1996). MIL 05035 [M], which is texturally similar to Asuka and compositionally similar to both Asuka 881757 and Yamato 793169, is likely part of the launch-pair group (Zeigler et al., 2007). MET 01210 [H] is a breccia that contains some feldspathic material. It appears to also be part of the YAMM launch-pair group on the basis of mineral and bulk composition (Arai et al., 2005; Zeigler et al., 2007). The data presented here are consistent with the launch-pairing hypothesis in that the composition of MET 01210 is consistent with a mixture of AYM material and material of the feldspathic highlands.

Other basaltic lunar meteorites. On the basis of the plots presented here, there is no strong reason to believe that Dhofar 287 [D,d], NEA 003 [E,e] or NWA 3136 [R] are related to any of the other basaltic lunar meteorites.

The breccia [d] portion of Dhofar 287 differs significantly from the basalt portion [D] and the breccia portion of NEA 003 [e] differs significantly from the basalt portion [E].

Bottom Line: Assuming that Kalahari 009, which we have not yet studied, is unpaired with any of the 27 stones discussed here, the basaltic lunar meteorites represent 14-15 meteorites and 8 craters on the Moon.

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See also subsample data for NWA 032/479 and the LAP stones.

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References

Arai T. and Warren P. H. (1999) Lunar meteorite Queen Alexandra Range 94281: Glass compositions and other evidence for launch pairing with Yamato 793274. Meteoritics & Planetary Science 34, 209-234.

Arai T., Misawa K. and Kojima H. (2005) A new lunar meteorite MET 01210: Mare breccia with a low-Ti ferrobasalt (abstract). In Lunar and Planetary Science XXXVI, abstract no. 2361, Lunar and Planetary Institute, Houston.

Jolliff B. L., Korotev R. L., Zeigler R. A., Floss C., and Haskin L. A. (2003) Northwest Africa 773: Lunar mare breccia with a shallow-formed olivine-cumulate component, very-low-Ti (VLT) heritage, and a KREEP connection. Geochim. Cosmochim. Acta 67, 4857–4879.

Korotev R. L., Jolliff B. L., Zeigler R. A., and Haskin L. A. (2003) Compositional constraints on the launch pairing of three brecciated lunar meteorites of basaltic composition, Antarctic Meteorite Research 16, 152–175.

Nishiizumi K., Hillegonds D. J., and Welten K. C. (2006) Exposure and terrestrial histories of lunar meteorites LAP 02205/02224/02226/02436, MET 01210, and PCA 02007 (abstract), In Lunar and Planetary Science XXXVII, abstract no. 2369, Lunar and Planetary Institute, Houston.

Thalmann C., Eugster O., Herzog G. F., Klein J., Krähenbühl U., Vogt S., and Xue S. (1996) History of lunar meteorites Queen Alexandra Range 93069, Asuka 881757, and Yamato 793169 based on noble gas isotopic abundances, radionuclide concentrations, and chemical composition. Meteoritics & Planetary Science 31, 857-868. 

Warren P. H. and Kallemeyn G. W. (1993) Geochemical investigations of two lunar mare meteorites: Yamato-793169 and Asuka-881757. Proc. NIPR Symp. Antarct. Meteorites 6, 35-57. Nat. Inst. Polar Res., Tokyo.

Zeigler R. A., Korotev R. L., Jolliff B. L., and Haskin L. A. (2005) Petrology and geochemistry of the LaPaz icefield basaltic lunar meteorite and source-crater pairing with Northwest Africa 032. Meteoritics & Planetary Science 40, 1073–1102.

Zeigler R. A., Korotev R. L., and Jolliff B. L. (2007) Petrography, geochemistry, and pairing relationships of basaltic lunar meteorite stones NWA 773, NWA 2700, NWA 2727, NWA 2977, and NWA 3160 (abstract). In Lunar and Planetary Science XXXVIII, abstract no. 2109. Lunar and Planetary Institute, Houston.