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Prograde amphibole dehydration reactions during high-grade regional metamorphism, central Massachusetts, USA

Journal Article · · American Mineralogist; (United States)
OSTI ID:5738609
 [1]
  1. Union College, Schenectady, NY (United States)
The study area extends for 80 km through regionally metamorphosed rocks in the metamorphic high of southern New England, in which Acadian (Devonian) metamorphism ranged from sillimanite-muscovite grade through sillimanite-garnet-cordierite-orthoclase grade. Over this metamorphic interval, amphibolites containing the assemblages plagioclase + hornblende {plus minus} quartz {plus minus} cummingtonite {plus minus} orthoamphibole {plus minus} garnet were transformed by a series of reactions into pyroxene granulites with assemblages of plagioclase + orthopyroxene + augite {plus minus} quartz {plus minus} hornblende {plus minus} garnet. Three particularly important reactions were examined in detail. These reactions, along with others, define an assemblage series in quartz-bearing rocks in the transition from amphibolite facies to granulite facies. This assemblage series is based on the coexistence of diagnostic minerals in common mafic rocks with increasing grade. This transition is estimated to have occurred over a temperature interval of 580-730C.
OSTI ID:
5738609
Journal Information:
American Mineralogist; (United States), Journal Name: American Mineralogist; (United States) Vol. 76:5-6; ISSN AMMIA; ISSN 0003-004X
Country of Publication:
United States
Language:
English