A Mixing Origin for Chondrite Groups

Introduction: Chondrites are known to contain varying proportions of chondrules, matrix, refractory inclusions and metal. Although trends are known to exist among the chondrite groups (e.g. [1]), their significance has seldom been discussed and no global understanding exists to date concerning the relationship between chondrite groups. Here we show that the relative abundances of the various petrographic components of chondrites follow simple patterns which allow us to trace 8 primary reservoirs from which all the main chondrite groups appear to have been generated. Method: We used literature data and our own measurements to construct a table of modal analyses of the petrographic constituents of chondrites from the various groups, restricting ourselves whenever possible to well characterized observed falls or fresh finds and to low-petrographic types (see [2] and the references therein). We searched for correlations between constituent abundances and found a correlation between vol% metal and vol % type I chondrules [3], which might have resulted from the formation of metal within type I chondrules, although in [2] we favored an accretionary origin for this trend. Correlations also exist between the abundances of CAIs and type I chondrules (Fig. 1).