Identification of relict forsterite grains in forsterite-rich chondrules from the Mokoia CV3 carbonaceous chondrite

摘要: Magnesium-rich forsterite grains (>Fo 98 ) in FeO-poor chondrules show variations cathodoluminescence (CL) intensity that are associated closely with Al 2 O 3 and TiO contents. CL thus can be used to map the distribution of Ti individual grains. We describe several categories distribution, including homogeneous, zoned continuously, oscillatory zoning, a heterogeneous intensity. Heterogeneous is interpreted as result disequilibrium growth from chondrule melt. surveys help identify potentially relics their host chondrules, i.e., did not crystallize situ Several these minor-element differ majority melt-grown chondrules: this observation supports inference they relics. Little evidence exists for multiple brief heating episodes. Identification abundance relict important determining thermal histories well nature precursor assemblages which formed.