New chemical data on coexisting cordierite + chlorite + biotite from Maine shows that on an AFM diagram, the biotite-cordierite join passes on the Mg-side of chlorite. This information has important implications for ascertaining the reactions that terminate the stability field of chlorite in pelitic schist.

Addition of the several cordierite-bearing assemblages to the AFM plots for the staurolite zone and lower sillimanite zone of northwestern Maine enables an almost complete topologic representation for each zone.

First Page Preview

First page PDF preview
You do not currently have access to this article.