Age, Origin, Regional Relations, and Nomenclature of the Glenarm Series, Central Appalachian Piedmont: A Reinterpretation

Oliverian domes, related plutonic rocks, and mantling Ammonoosuc Volcanics of the Bronson Hill Anticlinorium, New England Appalachians

“…In fact, the bimodal and K-poor nature of the Ammonoosuc Volcanics, coupled with their relatively high proportion of felsic rocks, places constraints on any island-arc model and precludes close analogies with modern arcs (Seiders, 1978; Leo, 1985). This problem has additional regional significance because similar lithologies are found throughout the Appalachian chain (Higgins, 1972; Seiders, 1978; Whitney and others, 1978;Malpas, 1979; Payne and Strong, 1979; Southwick, 1979;Pavlides, 1981; Leo and others, 1984). A broad regional synthesis given by Tucker and Robinson (1990) is based primarily on new U-Pb isotopic ages on Ammonoosuc Volcanics and related rocks in northern Massachusetts.…”

Journal of Research of the U. S. Geological Survey, 1974, volume 2, issue 5

“…Before then, this rock type had been mapped by others as the Skyesville Granite in Maryland. Higgins (1972, fig. 1) extended the diamictite unit too far to the south (Pavlides, 1974;Higgins, 1974) of the limits shown in figures 3 and 4.…”

“…Higgins (1972, fig. 1) extended the diamictite unit too far to the south (Pavlides, 1974;Higgins, 1974) of the limits shown in figures 3 and 4. The Chopawamsic Formation consists of metamorphosed mafic volcaniclastic and volcanic rocks and felsic volcanic rocks, as well as minor beds of clastic metasedimentaiy rocks.…”

“…age. Higgins (1972) assigned most of the Wissahickon Formation of Maryland and Virginia to the Cambrian. The Chopawamsic Formation is considered to overlie conformably and also to interfinger locally with the diamictite (pebble gneiss) unit (Southwick and others, 1971).…”

Geological Survey research 1980

“…The debate that followed concerning the age of the Quantico eventually focused on the reliability of zircon ages in dating the Dale City pluton and the adamellite (Higgins, 1976) in the nearby Occoquan Granite and (or) whether most zircon ages from the Piedmont were reliable for establishing ages of crystalline rocks (Higgins and others, 1977;Seiders, 1978;and Zartman, 1978).…”