Forsterite‐bearing type B refractory inclusions from CV3 chondrites: From aggregates to volatilized melt droplets

摘要: Detailed petrologic and oxygen isotopic analysis of six forsterite-bearing Type B calcium-aluminum-rich inclusions (FoBs) from CV3 chondrites indicates that they formed by varying degrees melting primitive precursor material resembled amoeboid olivine aggregates. A continuous evolutionary sequence exists between those objects experienced only slight partial or sintering through underwent prolonged episodes. In most cases, was accompanied surface evaporative loss magnesium silicon. This resulted in outer margins are very different composition the cores, so much some mantles contain mineral assemblages petrologically incompatible with cores. The for these FoBs had a range bulk compositions must therefore have under conditions if condensed solar gas. Five show small mass-dependent fractionation pyroxene, spinel, olivine, consistent inferred melt evaporation, but there no differences among three phases. Forsterite, pyroxene 16 O-rich D 17 O )24& all FoBs. Melilite anorthite )17& to )1&.