Geochemistry and chronology of the Bunburra Rockhole ungrouped achondrite
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Abstract-Bunburra Rockhole is a unique basaltic achondrite that has many mineralogicaland petrographic characteristics in common with the noncumulate eucrites, but differs in itsoxygen isotope composition. Here, we report a study of the mineralogy, petrology,geochemistry, and chron ology of Bunburra Rockhole to better understand the petrogenesisof this meteorite and compare it to the eucrites. The geochemistry of bulk samples and ofpyroxene, plagioclase, and Ca-phosphate in Bunburra Rockhole is similar to that of typicalnoncumulate eucrites. Chronological data for Bunburra Rockhole indicate early formation,followed by slow cooling and perhaps multiple subsequent heating events, which is alsosimilar to some noncumulate eucrites. The26Al-26Mg extinct radionuclide chronometer wasreset in Bunburra Rockhole after the complete decay of26Al, but a slight excess in theradiogenic26Mg in a bulk sample allows the determination of a model26Al-26Mg age thatsuggests formation of the parent melt for this meteorite from its source magma within the?rst ~3 Ma of the beginning of the solar system. The207Pb-206Pb absolute chronometer isalso disturbed in Bunburra Rockhole minerals, but a whole-rock isochron provides are-equilibration age of ~4.1 Ga, most likely caused by impac t heating. The mineralogy,geochemistry, and chronology of Bunburra Rockho le demonstrate the similarities of thisachondrite to the eucrites, and suggest that it formed from a parent melt with acomposition similar to that for noncumulat e eucrites and subsequently experienced athermal history and evolution comparable to that of eucritic basalts. This implies theformation of multiple differentiated parent bodies in the early solar system that had nearlyidentical bulk elemental compositions and petrogenetic histories, but different oxygenisotope compositions inherited from the solar nebula.
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Spivak-Birndorf, L.; Bouvier, A.; Benedix, G.; Hammond, S.; Brennecka, G.; Howard, K.; Rogers, N.; Wadhwa, M.; Bland, Phil; Spurný, P.; Towner, Martin (2015)Bunburra Rockhole is a unique basaltic achondrite that has many mineralogical and petrographic characteristics in common with the noncumulate eucrites, but differs in its oxygen isotope composition. Here, we report a study ...
Welten, K.; Meier, M.; Caffee, M.; Laubenstein, M.; Nishizumi, K.; Wieler, R.; Bland, Philip; Towner, M.; Spurný, P. (2012)Bunburra Rockhole is the first meteorite fall photographed and recovered by the Desert Fireball Network in Australia. It is classified as an ungrouped achondrite similar in mineralogical and chemical composition to eucrites, ...
Benedix, Gretchen; Bland, Phil; Friedrich, J.; Mittlefehldt, D.; Sanborn, M.; Yin, Q.; Greenwood, R.; Franchi, I.; Bevan, Alexander (2017)Bunburra Rockhole is the first recovered meteorite of the Desert Fireball Network. We expanded a bulk chemical study of the Bunburra Rockhole meteorite to include major, minor and trace element analyses, as well as oxygen ...