Petrology and geochemistry of chondrules and metal in nwa 5492 and gro 95551: a new type of metal-rich chondrite
Michael K. Weisberg, Denton S. Ebel, Daisuke Nakashima, Noriko T. Kita, Munir Humayun
Geochimica et Cosmochimica Acta
available online 22 July 2015
Oxygen isotope ratios of chondrules in NWA 5492 and GRO 95551 show considerable overlap with chondrules in O, E and R chondrites, with average compositions indistinguishable from LL3 chondrules, suggesting considerable mixing between these Solar System materials during chondrule formation and/or that their precursors experienced similar formation environments and/or processes. Another characteristic shared between NWA 5492 and GRO 95551 and O, E and R chondrites is that they are all relatively dry (low abundances of hydrated minerals), compared to many C chondrites and have fewer, smaller CAIs than many C chondrites. (No CAIs were found in NWA 5492 or GRO 95551 but they contain rare Al-rich chondrules.) We suggest that O, E, R and the NWA 5492 and GRO 95551 chondrites are closely related Solar System materials.