Deep transverse basement structural control of mineral systems in the southeastern Canadian Cordillera1Geological Survey of Canada Contribution 20110294.

Abstract

Intermittent reactivation of deep Paleoproterozoic- and Archean-aged transverse structures in the North American cratonic basement beneath the southeastern Canadian Cordillera exerted an important influence on the subsequent sedimentary, intrusive, deformation, and mineralization history. Two regional crossbelt transverse structural corridors recognized by recurrent episodic changes in sediment thickness and facies, and anomalous transverse structural trends, occur within the thrust and fold belt. Palinspastic restoration of the exposed transported structural corridors showed that the northern and southern structural corridors are cover expressions of the Red Deer zone and Vulcan Low structures in the cratonic basement, respectively. Transverse basement-controlled structural corridors enhanced the mineral potential and mineralization systems along them by localization of sedimentary facies favourable for mineralization, hydrothermal flow, intrusions, and favourable structures for mineralization. Greatest enhancement of hydrothermal flow and mineralization occurred near the intersection of basin-parallel and transverse structures. Greater opportunity for mineralization and intrusion occurred not only along the exposed corridors, but also in the west, above their undeformed “root” in the basement. The processes that intensified mineralization and localized intrusions along transverse basement-controlled structural corridors in the southeastern Canadian Cordillera should have occurred in thrust and fold belts elsewhere. The niobium-bearing Aley carbonatite complex in the eastern Cordillera of northeastern British Columbia may be an example of this.