53 Mn- 53 Cr SYSTEMATICS OF ALLENDE CHONDRULES AND ε 54 Cr—Δ 17 O CORRELATION IN BULK

Cr data for bulk carbonaceous chondrites [1,2] imply that chondrules in them must also have formed early, given the logical necessity of forming chondrules first before accreting chondrites (we need “sand grains” first to form the cosmic “sandstone”). This simple temporal relationship is, however, at odds with the currently ac-cepted chondrule