ALUMINOUS ENCLAVES IN GEDRITE-CORDIERITE GNEISS FROM SOUTHWESTERN NEW HAMPSHIRE

Gedrite-cordierite gneisses interbedded with other mafic rocks from Middle Ordovician Ammnoosuc Volcanics of Richmond, New Hampshire, contain aluminous enclaves in cordierite composed of kyanite, sillimanite, corundum, staurolite, spinel, and bytownite; original gedrite-kyanite- sillimanite gneisses reacted to form cordierite so that remnant aluminosilicates are nowhere in contact with dedrite; phase analysis using compositional information suggests that enclave assemblages resulted from continuous reactions which formed progressively more Fe-rich cordierite with changing pressures and temperature.