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    Lunar and docsou.comience XXXIX (2008)
    1631.pdf
    docsou.comT AFRICA 4898: A NEW HIGH-docsou.comA MARE docsou.comOM THE MOON. Ansgar docsou.comake1, Anthony J. docsou.comg2, Scott M. docsou.comer2, Randy L. Korotev3, Marko docsou.comn4, and docsou.comrt Palme4, 1 docsou.comm für docsou.com, Humboldt-Universitt docsou.comrlin, docsou.comrlin, Germany (ansgar.docsou.comake@rz.docsou.com), docsou.coment of Earth and docsou.comdocsou.com, University of docsou.comgton, Seattle, WA 98195, USA, 3 docsou.coment of Earth and docsou.comdocsou.com, docsou.comgton University, St. Louis, MO 63130, USA, 4Institut für Geologie und Mineralogie, Universitt zu Kln, 50674 Kln, Germany. docsou.comn. docsou.comdocsou.comnar rocks and soils returned by the Apollo docsou.comna docsou.comns and data docsou.comom docsou.comnar orbiters, docsou.comom the Moon are a valuable source docsou.comdocsou.comn on its docsou.comn and geological docsou.comn. Of the 58 docsou.comnar docsou.com recovered so far, the majority are docsou.comth docsou.comagmental docsou.comias, and only very few are docsou.comed mare basalts [1]. We report here on a new type of high-docsou.coma mare docsou.comom the Moon. Mineralogy and docsou.comy. NWA 4898 is a single 137 g individual stone docsou.comdocsou.comvered with docsou.comn crust that was docsou.com an docsou.comd docsou.com 2005. The docsou.comows a docsou.comdocsou.comr texture docsou.comdocsou.comhedral to subhedral docsou.come docsou.comrysts or clusters of docsou.comt into a groundmass of chemically zoned pigeonite and augite as well as docsou.com (maskelynite) laths (Fig. 1a,b). docsou.comdocsou.comdocsou.com abundant needle and docsou.come docsou.comaped docsou.com, docsou.comhedral docsou.com, and rare docsou.comte and Fe-Ni metal. A pure docsou.comase (probably docsou.comte) is docsou.comnt docsou.com the docsou.com docsou.comtween docsou.com and the mafic minerals. Many docsou.comns of the rock have a pronounced docsou.comtic appearance due to sprays of clinopyroxene and docsou.com (Fig. 1a,b). docsou.comdocsou.com or Zr-docsou.comases were found. docsou.come docsou.comrysts docsou.comdocsou.comnally zoned and docsou.comdocsou.com chromite and/or docsou.comdocsou.comns (Fig. 1a,b). docsou.com docsou.come and pyroxene clump together to form docsou.comyric docsou.com. docsou.com docsou.comdocsou.comnally zoned and mostly subhedral to docsou.comic pigeonite and augite. Some docsou.com are very Fe-rich; orthopyroxene is not docsou.com docsou.comctions studied. Due docsou.comock docsou.comism docsou.com docsou.comdocsou.comdocsou.comto maskelynite. The docsou.coms docsou.comantly occur as chemically docsou.comths or blocky crystals generally docsou.comarp docsou.com to the docsou.comg minerals. Some maskelynite docsou.coms docsou.comtically docsou.com pyroxene. In the sprays the maskelynite is docsou.comnt as docsou.comterstitial docsou.com between pyroxene (Fig 1a). Among the docsou.comases ilmenite is by far the most abundant. The mostly docsou.comaped docsou.coms docsou.comdocsou.come on the crystals docsou.com of docsou.come and docsou.comut the primary texture of pyroxene and docsou.com. Chromite typically occurs docsou.comhedral docsou.coms either docsou.com docsou.come (Fig. 1a) or docsou.comdocsou.come, chemically zoned docsou.coms or clusters of docsou.com the matrix (Fig. 1d,e). docsou.comdocsou.comns. docsou.comive docsou.com docsou.comdocsou.com NWA 4898 are docsou.com Table 1. docsou.come docsou.comrysts have Fe-docsou.comres (Fa26.3; docsou.comO = 75.8; CaO = 0.26-0.82 wt.%) and Fe-rich rims (Fa44.1; docsou.comO = 151; CaO = 0.28-0.38 wt.%). Pigeonite docsou.comom Fs25.1-44.8Wo10-19.9 (docsou.comO = 47.6-73.4; TiO2 = 0.55-1.32 wt.%) and docsou.comom Fs25-58.7Wo20.238.3 (docsou.comO = 44.4-76.3; TiO2 = 0.76-2.23 wt.%). Rare ferroan docsou.com have Fs72.4-75.6Wo10.8-23.9 and docsou.comO = 70.8-74.4. The docsou.comths docsou.comsentially K-free An91.9-96.5 docsou.comdocsou.com docsou.comounts of SrO (0.02 wt.%). Elemental docsou.comg reveals a symmetric docsou.comg of Al and docsou.com docsou.comths (Fig. 1c). The small docsou.comtic docsou.com docsou.comdocsou.com a much narrower range (An91.9-96.5Or0.3) docsou.comdocsou.com up to 0.08 wt.% SrO. Spinel is mostly titanian chromite with Cr/(Cr+Al) = 0.581, Mg/(Mg+Fe) = 0.226, and TiO2 = 2.25 wt.% overgrown by chromian docsou.comel with Cr/(Cr+Al) = 0.581, Mg/(Mg+Fe) = 0.226, and TiO2 = 23 wt.%; docsou.comdocsou.comdocsou.comre and rim docsou.comdocsou.comarp rather docsou.comdocsou.com (Fig. 1e). docsou.comdocsou.comn docsou.come. Bulk docsou.com by XRF spectrometry docsou.comAA docsou.comd: (in wt.%) SiO2 46.15, TiO2 2.39, Al2O3 11.98, Cr2O3 0.43, FeO 17.34, MnO 0.25, MgO 8.31, CaO 11.43, Na2O 0.30, P2O5 <0.06; (in ppm) Ni <180, Co 24.8, V 120, Sc 65.4, Zr 145, La 4.71, Ce 14.8, Nd 12, Sm 4.55, Eu 0.997, Tb 1.06, Yb 4.00, Lu 0.570, Hf 4.45, Ta 0.24, Th 0.44. The REE docsou.comows a docsou.com anomaly [2], and a Rb-Sr docsou.come of 3.58 Ga docsou.comdocsou.comed by [3]. Shock docsou.comism. All docsou.com the docsou.comow signs of docsou.comock docsou.comism. docsou.come docsou.comdocsou.comts of planar and docsou.comdocsou.com and strong mosaicism. docsou.com docsou.comdocsou.comdocsou.comto maskelynite, pyroxene and chromite docsou.comdocsou.comactured, and docsou.comdocsou.comdocsou.comg. The docsou.comen is docsou.comut docsou.comock veins which appear docsou.com docsou.comght. The veins docsou.comow fluidal docsou.com docsou.comdocsou.comrger docsou.comagments. More rarely, local docsou.comg of mostly pyroxene and melt pockets with docsou.com droplets are docsou.comnt. docsou.comg to [4] the docsou.comdocsou.com docsou.comock stage 2b, and experienced an docsou.comock pressure of ~28-34 GPa and a docsou.comock docsou.comure of ~200-250°C. docsou.comn docsou.comdocsou.comns. Based upon its texture and docsou.comdocsou.comn, NWA docsou.comitially docsou.com a docsou.comva flow or a magma docsou.com docsou.compths with the docsou.comg docsou.comquence: spinel → docsou.come → pigeonite → augite → docsou.com → ilmenite (together with docsou.comel overgrowth) → SiO2-docsou.coms. The sprays of docsou.com and clinopyroxene then formed docsou.comg docsou.comom the residual melt while the basalt was quickly erupted or

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