On the Remelting of Type B Calcium-Aluminum-rich Inclusions

We have shown [1-3] that the variation in the minor-element concentration of spinels (MgAI_20_4 and their relationship to host silicate chemistry from type B CAIs is a powerful tool in constraining the igneous history of these objects. We conducted electron microprobe studies of the minor-element distributions among spinels from three type Bl CAIs: Allende TS-34, Allende TS-23, and Leoville 3537-2. By maintaining the petrologic context (edge, middle, and center of the inclusion plus their host silicate phase), four populations of spinels are resolvable based on their positive TI to V correlation. Grains from the middle and center areas define trends that are divided into three populations: spinels enclosed by melilite, fassaite, and anorthite. These grains also show important TI, V, and Cr correlations with their host silicate chemistries. The other population resides within the edge area (mainly mantle melilite) and is characterized by the highest V contents with little chemical relationship to their host silicates.