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Abstract

To understand the Mesozoic-Cenozoic development of the North American continental margin, it is of prime importance to gain a knowledge of the tectonic framework of the continent. A review of this framework provides the foundation for discussion of the evolution of the continental margin. The northern part of the North American continent is dominated by the Canadian shield (Fig. 321), a tectonic province consisting mainly of metamorphic and plutonic infracrustal rocks. These rocks are divided into several fold belts that are the products of the Grenville orogeny (880–1,000 m.y.; Grenville fold belt), the Hudsonian orogeny (1,640–1,820 m.y.; Churchill, Southern, Bear, and Nain fold belts), and the Kenoran orogeny (2,390–2,600 m.y.; Superior, Slave, and Nain fold belts; P. B. King, 1969b). On top of these fold belts are less disturbed postorogenic sedimentary and volcanic (Fig. 321) Precambrian platform deposits. This Precambrian terrane was depressed toward the south to form the foundation for Paleozoic and younger platform deposits.

East of the platform tectonic province is the Appalachian system that was deformed during the Paleozoic, with major deformations occurring during the Taconic (Ordovician) and Acadian (Devonian) revolutions and the Allegheny (Permian) disturbance. The deformed belt consists of a narrow miogeosyncline in the northwest composed of folded and thrust-faulted sedimentary rocks. Southeast of the miogeosyncline is a broad eugeosyncline of de-formed and metamorphosed sequences of sedi-mentary and volcanic rocks intruded by plutonic masses. Between these two geosynclines are long strips of Precambrian rocks that are uplifted parts of the basement

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