Abstract

Textural interpretations combined with the areal distribution of metamorphic assemblages and chemistry of muscovite and chlorite in the Silurian-Devonian Goshen Formation of western Massachusetts dictate three episodes of metamorphism during the Devonian Acadian orogeny. The first and third episodes are interpreted as prograde events and the second as retrograde. The first metamorphic event (prograde) produced kyanite and staurolite. The second event (retrograde) produced chlorite and paragonite at the expense of previously formed prograde minerals. The third event resulted locally in the prograde replacement of chlorite embayments in garnet by biotite, muscovite, and quartz. Chemical reactions are suggested for each of the three metamorphic events.

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