Accreted island arcs and cross-cutting batholithic belts of the North American Cordillera

Abstract

The basement framework of the western Cordillera consists in large part of tectonically accreted island arc terranes and cross-cutting batholithic belts. The arc terranes are diverse in terms of magmatic history, tectonic disruption and basement relations, and represent several distinct systems. Terranes of the two oldest systems occur in inner and outer belt positions. The inner belt runs from central Alaska to the northern Sierra Nevada. It was in its major developmental phases by the Devonian, and was constructed on imbricated North American continental rise strata outboard of a passive margin. The outer belt includes the Alexander Terrane (AT) of SE Alaska and younger amalgamated arc terranes of the Alaska Peninsula and Queen Charlotte-Vancouver Islands.