Northwest Africa 773: lunar mare breccia with a shallow-formed olivine-cumulate component, inferred very-low-Ti (VLT) heritage, and a KREEP connection

Jolliff, Bradley L.; Korotev, R. L.; Zeigler, R. A.; Floss, C.

doi:10.1016/j.gca.2003.08.012

Cited by 62 publications

(124 citation statements)

References 48 publications

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“…Preliminary reports indicate the same is true for NWA 2977. This rock has bulk chemical characteristics similar to the very low-titanium basalts; however, its incompatible trace element signature is similar to that of KREEP (50,51), making this a unique sample among other lunar mare basalts (50,51). The mineralogy of NWA 2977 is broadly consistent with the olivine-gabbro cumulate clasts described in NWA 773, consisting primarily of olivine, pyroxene, and plagioclase.…”

Section: Resultsmentioning

confidence: 66%

“…Although NWA 2977 has not been previously investigated for terrestrial contamination, carbonate deposits have been reported to occur on the exterior portions of lunar meteorite NWA 773 [paired with NWA 2977 (48)], and calcite-rich fracture fillings have also been observed within thin sections of this meteorite (50). Importantly, the silicates in NWA 773 lack observable alteration in thin section, even along fracture boundaries (50), and the same holds true for NWA 2977. Moreover, the Fe-rich Fe-Ni metal grains in both meteorites are intact and unaltered (ref.…”

Section: Resultsmentioning

confidence: 95%

“…Lunar meteorite Northwest Africa (NWA) 2977 is an olivine-gabbro cumulate that is paired with lunar meteorite NWA 773 (48), which contains clasts of the same olivine-gabbro cumulate lithology (49,50). The crystallization age of the olivine-gabbro cumulate in NWA 773 is 2.86 Ga (51), and no trapped solar wind was detected in this lithology, indicating a very limited residence time at the lunar surface (52).…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the Fe-rich Fe-Ni metal grains in both meteorites are intact and unaltered (ref. 50; Fig. 3B), which would not be the case if the rocks underwent sufficient contamination to "reset" the volatile contents of the apatite.…”

Section: Resultsmentioning

confidence: 99%

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Nominally hydrous magmatism on the Moon

McCubbin

Steele

Hauri

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

275

185

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For the past 40 years, the Moon has been described as nearly devoid of indigenous water; however, evidence for water both on the lunar surface and within the lunar interior have recently emerged, calling into question this long-standing lunar dogma. In the present study, hydroxyl (as well as fluoride and chloride) was analyzed by secondary ion mass spectrometry in apatite [Ca 5 ðPO 4 Þ 3 ðF,Cl,OHÞ] from three different lunar samples in order to obtain quantitative constraints on the abundance of water in the lunar interior. This work confirms that hundreds to thousands of ppm water (of the structural form hydroxyl) is present in apatite from the Moon. Moreover, two of the studied samples likely had water preserved from magmatic processes, which would qualify the water as being indigenous to the Moon. The presence of hydroxyl in apatite from a number of different types of lunar rocks indicates that water may be ubiquitous within the lunar interior, potentially as early as the time of lunar formation. The water contents analyzed for the lunar apatite indicate minimum water contents of their lunar source region to range from 64 ppb to 5 ppm H 2 O. This lower limit range of water contents is at least two orders of magnitude greater than the previously reported value for the bulk Moon, and the actual source region water contents could be significantly higher. O ne of the scientific discoveries resulting from the Apollo missions was the pervasive waterless nature of the Moon and its rocks. The initial studies of the returned samples were pristine and showed no evidence of aqueous alteration, and water analyses were below detection limits. Moreover, hydrous phases were absent from the lunar rocks aside from a few unconfirmed reports of possible amphibole grains (1), which are now considered by many to represent either misidentifications or terrestrial contamination (as summarized by ref. 2). The subsequent forty years of lunar sample analysis have only supported and strengthened the idea that indigenous water was nearly absent from the Moon's interior. In fact, this conclusion has been incorporated into many petrologic and geophysical models constructed to aid in our understanding of lunar formation and lunar geology (3-11). The bulk water content of the Moon was recently estimated to be less than 1 ppb (11), which would make the Moon at least six orders of magnitude drier than the interiors of Earth (12, 13) and Mars (14). This extremely low water content is in keeping with the pervasive volatile-element depletion signature recorded in all lunar materials, because hydrogen is the most volatile of the elements. The exact cause for this volatile-element depletion is still under question; however, many have argued that it stems from the high temperatures associated with the Moon-forming giant-impact event at ∼4.5 Ga (i.e., refs. 3,8,15,and 16).Facilitated by advancements in analytical detection sensitivities for water, several recent discoveries have indicated that the story of water on the Moon is far from complete. Evi...

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Section: Resultsmentioning

confidence: 66%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Nominally hydrous magmatism on the Moon

McCubbin

Steele

Hauri

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

275

185

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show abstract

“…The 87 Sr/ 86 Sr and 143 Nd/ 144 Nd isotopic evolution of the lunar mantle source regions of the LAP parent magma, Apollo 12 and 15 olivine basalts, and KREEP are modeled assuming two-stage models ( Figure 8A and B) with the mixing parameters listed in Table 3 (data from this study, Borg et al, 2004;Gnos et al, 2004;Jolliff et al, 2003;Neal, 2001;Nyquist and Shih, 1992;Nyquist et al, 1995;Rankenburg et al, 2006;Snyder et al, 1997). Because the trace element abundances in the SaU 169 impact melt breccia are the highest among the KREEP-rich samples, it probably represents a relatively 'pure' KREEP composition, and the REE and Sr concentrations of SaU 169 (Gnos et al, 2004) are therefore used in the mixing calculations.…”

Section: Sr-nd Isotope Mixing Modelsmentioning

confidence: 99%