Ion and electron microprobe study of troctolites, norite, and anorthosites from Apollo 14: evidence for urKREEP assimilation during petrogenesis of Apollo 14 Mg-suite rocks

Shervais, John W.; McGee, J. J.

doi:10.1016/s0016-7037(98)00195-1

Cited by 58 publications

(45 citation statements)

References 31 publications

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“…NWA 773 clearly bears a closer resemblance to the gabbronorite subgroup in mineralogy, although baddeleyite, which is associated with the norite subgroup (James and Flohr 1983), is present in NWA 773. Inversion of ion microprobe analyses of plagioclase feldspar and pyroxenes from magnesian suite norites, troctolites, and anorthosites indicate that many of these rocks crystallized from liquids with KREEP-like trace element signatures (Papike et al 1996;Shervais and McGee 1998). In general, this conforms with similar calculations for NWA 773 by Bridges et al (2002) and with the whole-rock trace element data reported here (Table 9) and elsewhere .…”

Section: Comparison With Other Lunar Rockssupporting

confidence: 91%

Northwest Africa 773: Lunar origin and iron‐enrichment trend

Fagan

Taylor

Keil

et al. 2003

Meteorit & Planetary Scien

120

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Abstract-The meteorite Northwest Africa 773 (NWA 773) is a lunar sample with implications for the evolution of mafic magmas on the moon. A combination of key parameters including whole-rock oxygen isotopic composition, Fe/Mn ratios in mafic silicates, noble gas concentrations, a KREEP-like rare earth element pattern, and the presence of regolith agglutinate fragments indicate a lunar origin for NWA 773. Partial maskelynitization of feldspar and occasional twinning of pyroxene are attributed to shock deformation. Terrestrial weathering has caused fracturing and precipitation of Carich carbonates and sulfates in the fractures, but lunar minerals appear fresh and unoxidized. The meteorite is composed of two distinct lithologies: a two-pyroxene olivine gabbro with cumulate texture, and a polymict, fragmental regolith breccia. The olivine gabbro is dominated by cumulate olivine with pigeonite, augite, and interstitial plagioclase feldspar. The breccia consists of several types of clasts but is dominated by clasts from the gabbro and more FeO-rich derivatives. Variations in clast mineral assemblage and pyroxene Mg/(Mg + Fe) and Ti/(Ti + Cr) record an igneous Fe-enrichment trend that culminated in crystallization of fayalite + silica + hedenbergitebearing symplectites.The Fe-enrichment trend and cumulate textures observed in NWA 773 are similar to features of terrestrial ponded lava flows and shallow-level mafic intrusives, indicating that NWA 773 may be from a layered mafic intrusion or a thick, differentiated lava flow. NWA 773 and several other mafic lunar meteorites have LREE-enriched patters distinct from Apollo and Luna mare basalts, which tend to be LREE-depleted. This is somewhat surprising in light of remote sensing data that indicates that the Apollo and Luna missions sampled a portion of the moon that was enriched in incompatible heatproducing elements.

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Section: Comparison With Other Lunar Rockssupporting

confidence: 91%

Northwest Africa 773: Lunar origin and iron‐enrichment trend

Fagan

Taylor

Keil

et al. 2003

Meteorit & Planetary Scien

120

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“…Figure 4 shows the Eu/Sm versus Sm systematics for Apollo samples and lunar meteorites including those from this study. Variations in plagioclase chemistry measured in lunar meteorites (this study, [15,31]) and Apollo highland rock suites [11,12,41,45,46]. Eu/Sm values are chondrite normalized [30] and scale is inverted to reflect Mg# versus An# trends in Apollo highland rock suite mafic and felsic minerals [9].…”

Section: Discussion (A) Comparison To Previous Work On Apollo and Lunmentioning

confidence: 99%

Heterogeneity in lunar anorthosite meteorites: implications for the lunar magma ocean model

Russell

Joy

Jeffries

et al. 2014

Phil. Trans. R. Soc. A.

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The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites: Dhofar 908 and Dhofar 081. The rare earth elements were present in abundances of approximately 0

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“…Superimposed on this diagram is the duration of primary lunar crust formation (FAN, ferroan anorthosite), Mg-suite magmatism, and KREEP-rich magmatism represented by the KREEP basalts, high-Al basalts, and olivine-gabbro clast in the NWA 773 meteorite. C. K. Shearer and J. J. Papike Snyder et al (1995) and Shervais and McGee (1999) modeled the variation in Ca/(CaϩNa) (or An content) in plagioclase vs. the Mg/(MgϩFe) observed in the Mg-suite as the fractional crystallization of a single KREEP basalt (Fig. 2).…”

Section: Summary Of Occurrence and Petrologymentioning

confidence: 99%

“…Early crustal building processes on the moon et al (1996) and Shervais and McGee (1999) (Table 4). Most of these ion microprobe data are primarily REE data and are combined with our measurements in Figures 10B and 11.…”

mentioning

confidence: 99%