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Chapter 12 Proterozoic Terranes and Continental Accretion in Southwestern North America

1992; Elsevier BV; Linguagem: Inglês

10.1016/s0166-2635(08)70126-9

2452-1892

Kent C. Condie,

High-pressure geophysics and materials

It is generally agreed that significant portions of the Appalachian and Cordilleran orogenic belts in North America are composed of accreted terranes. Despite limited exposure, the geological and geochemical studies of Proterozoic supracrustal successions in southwestern North America suggest that much of this region also comprises accreted terranes that were added to North America during the Early and Middle Proterozoic. Similar terranes were accreted to Archean crust in Scandinavia at about the same time. Several terms have been used for the segments of continental crust associated with continental accretion, and because they may be used in different ways in this chapter, it is important to define the terms. “Terrane” follows the conventional usage of Jones et al. and Coney (1989) and refers to a fault-bounded segment of continental crust with a distinctive assemblage of rocks and a tectonic history different from surrounding terranes. A “superterrane” (or composite terrane) results from the amalgamation of two or more terranes prior to final accretion with a continent, and an “overlap assemblage” is an assemblage of supracrustal rocks that overlaps older terrane boundaries.