Multistage formation processes in the acapulcoite-lodranite parent body: Mineralogical study of anomalous lodranite, Yamato 983119

Y 983119 is a coarse-grained rock consisting mainly of orthopyroxene (44-71 vol%, Wo3En94Fs4), olivine (4-30 vol%, Fo97), Fe, Ni metal (4-14 vol%) and interstitial plagioclase (9-14 vol%, Or2Ab67An29) and augite (2-5 vol%, Wo46En53Fs2). The modal abundance of orthopyroxene is higher than known acapulcoites and lodranites. Olivine grains show chemical zoning with higher Fe/Mn values along rims and cracks. Orthopyroxene and olivine contain melt inclusions that mainly consist of augite, feldspar and glass. Hornblende, biotite, rutile and baddeleyite were also found in melt inclusions. Based on the compositions of melt inclusions, the parent melt is felsic, and contains a significant amount of Na, K, Ti, Zr, F and OH. The major mineral and oxygen isotopic compositions indicate that Y 983119 is a lodranite. However, the high abundance of orthopyroxene and the presence of melt inclusions indicate that Y 983119 is not a residue in contrast to other lodranites. We suggest that Y 983119 formed by more complex formation processes than the other lodranites.