Comparison of some tectonostratigraphic zones in the Appalachians of Newfoundland and New Brunswick

Abstract

Whereas rocks of the Avalon Zone in Newfoundland are in fault contact with those of the Gander Zone, rocks identifiable as equivalents of the Gander Zone in New Brunswick are separated from the Avalon Zone by a 65 km wide belt of Silurian, Ordovician, and older rocks. This belt, referred to as the Fredericton Zone, contains a number of fault bounded blocks, each containing contrasting depositional, structural, and metamorphic histories. It is concluded that the Gander/Avalon Zone boundary in southern New Brunswick has controlled the development of subsequent basins, which have been deformed by Taconic and Acadian movements. In Newfoundland, the same boundary has remained essentially inactive in Paleozoic times.

Origin and U–Pb geochronology of amphibolite-facies metamorphic rocks, Miramichi Highlands, New Brunswick

“…The Precambrian age assigned to the high-grade metamorphic rocks of central New Brunswick by comparison with inferred Precambrian rocks of the Gander Zone of Newfoundland (Rast et al 1976) has not been substantiated by the geochronologic data presented here. Instead, the felsic orthogneisses and augen granites in the Mirarnichi Highlands are confirmed to be Late Ordovician (this study; Whalen and Bevier 1987) and, hence, coeval with volcanic rocks of the Tetagouche Group.…”

“…The regional cordierite isograd is used as the boundary between (3) and (4). either as part of the Tetagouche Group (Skinner 1975;Fyffe 1977) or as a Precambrian basement complex that is separated from younger rocks by an inferred unconformity (Rast et al 1976;Fyffe and Pronk 1985). The age assigned by Rast et al (1976) was based on a correlation with a similar rock association of supposed Precambrian age in the Gander Zone of Newfoundland.…”

“…either as part of the Tetagouche Group (Skinner 1975;Fyffe 1977) or as a Precambrian basement complex that is separated from younger rocks by an inferred unconformity (Rast et al 1976;Fyffe and Pronk 1985). The age assigned by Rast et al (1976) was based on a correlation with a similar rock association of supposed Precambrian age in the Gander Zone of Newfoundland. If, on the other hand, the high-grade rocks are related to the Tetagouche Group, they would be Ordovician in age and probably formed in an intracontinental back-arc setting (van Staal 1987).…”

Provenance of tectonic history of the Gander Zone in the Caledonian/Appalachian Orogen: Implications for the origin and assembly of Avalon

“…On the basis of lithological characteristics, age, and nature of its cover, the Gander clastic rocks have been correlated also with the Cambrian to Lower Ordovician Miramichi and Cookson groups ( Fig. 1) of central and southern New Brunswick (Rast et al, 1976;Fyffe et al, 1983;Fyffe and Fricker, 1987; van Staal and Fyffe, 1991). Both the Miramichi and Cookson groups extend into adjacent Maine (Neuman, 1984;Ludman, 1987;Berry and Osberg, 1989).…”

Geomagnetic Sounding of an Ancient Plate Margin in the Canadian Appalachians

“…There is little evidence for a broad area of abnormally high conductivity under the central mobile belt in Newfoundland manifested in a region of low transfer function amplitudes as occurs in Virginia (EDwARDS and GREEN-HOUSE, 1975) or the western Cordillera (COCHRANE and HYNDMAN, 1970;CANER et al, 1971). If the conductive region is restricted to the Gander Zone geological inference is that its westward extension lies through north-central New Brunswick (RAST et al, 1976). Northeastward from Newfoundland the Gander Zone can be traced by other geophysical evidence as a narrow linear feature to the vicinity of the continental margin (JAcoBI and KRISTOFFERSEN, 1976).…”