Detrital zircon geochronology and rift-related magmatism : central Mackenzie Mountains, Northwest Territories ...

• Main Author: Leslie, Christopher Dean
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Northwest Territories; Mackenzie mountains
• Online Access: https://dx.doi.org/10.14288/1.0052744; https://doi.library.ubc.ca/10.14288/1.0052744

Neoproterozoic to Cretaceous age strata in the Mackenzie Mountains of the northern Canadian Cordillera record many geological events that affected the western margin of Ancestral North America. Two of these events that are the focus of this study are; (1) the development of a thick long-lived passive margin sequence of sedimentary rocks; and (2) continental rifting of this passive margin in Ordovician time that was accompanied with alkaline volcanism of the Marmot Formation. Sedimentary units from throughout the Mackenzie Mountains stratigraphy contain ubiquitous detrital zircons with U-Pb ages of 2800 – 2415 Ma and 2080 – 1700 Ma; these reflect a component of sediment derived from basement sources of western Laurentia. More surprising is the abundance of “anomalous” detrital zircons ages (e.g., 1800 – 1000 Ma) in these units that cannot be linked to known local sources. The most likely source for detrital zircons of these ages are felsic igneous rocks now exposed in southern and eastern North America. We ...