John T. Cheney

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Mountain, Skitchewaug and Big Staurolite nappes. Reactivation of A new, detailed tectonic model is presented for the Acadian orogenic this fabric during thrusting is recorded in some rocks of the Big belt of central New England (Vermont and New Hampshire) that Staurolite nappe by rotated garnets that grew during near-isothermal accounts for a wide range of(More)
Numerous rod-shaped calcite crystals occur in the blueschist to eclogite facies marbles of Syros, Greece. The rods show a shape-preferred orientation, and the long axes of the rods are oriented at a large angle to foliation. The crystals also have a crystallographic-preferred orientation: calcite c-axes are oriented parallel to the long axes of the rods.(More)
Four distinct generations of monazite growth have been identified in samples from the Chesham Pond Nappe, and three (monazite compositional domains 2, 3 and 4) have been correlated with both temperature and mineral assemblage. Domain 1 cores were previously interpreted to be detrital relics or vestiges of an earlier Acadian metamorphism. The four monazite(More)
permission to individual scientists to make unlimited photocopies of one or more items from this volume for noncommercial purposes advancing science or education, including classroom use. For permission to make photocopies of any item in this volume for other noncommercial, nonprofit purposes, contact the Geological Society of America. Written permission is(More)
Integrated studies by Keck Geology Consortium participants have generated many new insights into the Precambrian geology of the Tobacco Root Mountains. We have clarifi ed the tectonic setting and origin of two suites of metamorphic rocks: (1) a quartzofeldspathic gneiss complex with associated metasupracrustal rocks (the combined Indian Creek and(More)
Talc occurs as massive, economic deposits in upper amphibolite facies marbles of Archean age in southwestern Montana. Previous workers have demonstrated that the talc is a replacement of the marble that resulted from interaction with a large volume of fluid. δ 18 O (SMOW) values for dolomite and calcite range from 20-25‰ for the unaltered Archean marbles to(More)
The island of Syros is made of a suite of glaucophane-bearing calcareous schists, mafic schists, and marbles. Lawsonite pseudomorphs stand in relief on the weathered surfaces of a number of blueschist outcrops on the island. They occur as white, seemingly euhedral, rectangular or diamond-shaped aggregates, 0.2 to 3.0 cm across. The pseudomorphs, some of(More)
The occurrence of glaucophane-bearing marbles on Syros is noteworthy because reports of marbles that contain glaucophane are rare among descriptions of high-pressure marbles. On Syros, the marbles are composed primarily of calcite with or without dolomite and quartz. Much of the calcite in these marbles shows oriented columnar structures that are(More)