Start |Author Index | View Uploaded Presentations | Meeting Information
Paper No. 4
Presentation Time: 8:45 AM

CAUSE AND EFFECT: LATE CRETACEOUS TECTONIC INVERSION AND BASIN HISTORY IN THE SOUTHERN CANADIAN CORDILLERA


MAHONEY, J.B., University of Wisconsin, Eau Clare, Eau Claire, 54701, HAGGART, James W., Geol Survey Canada, 625 Robson St, Vancouver, BC V6B 5J3, Canada, KIMBROUGH, David L., Geological Sciences, San Diego State University, San Diego, CA 92182 and GROVE, Marty, Department of Geological Sciences, Stanford University, Stanford, CA 94305, mahonej@uwec.edu

Rapid orogenic exhumation in the southern Canadian Cordillera is recorded by the tectonic inversion of the Cretaceous Methow basin, coupled with rapid basinal subsidence and initiation of the peripheral foreland Nanaimo basin.

The composite Methow/Methow-Tyaughton basin records a complex basin evolution that initiated with Hauterivian(?) to Albian sedimentation in a forearc basin receiving easterly-derived volcanoplutonic detritus. Facies variations, subsidence rates, and the association between sedimentation and contractional deformation all suggest that the forearc basin was superseded in middle Albian time by structurally controlled subsidence in a complex hybrid foreland basin setting. Sedimentation in the Methow/Methow-Tyaughton basin ended by at least Coniacian time, coincident with the culmination of deformation in the Coast Belt thrust system along the western margin of the basin.

The Nanaimo basin is a peripheral foreland basin formed along the western edge of the Insular Superterrane in southwestern British Columbia. Subsidence initiated in Turonian time in response to contractional crustal thickening in the southern Coast Belt and Cascade Range to the east and southeast. Subsidence increased dramatically during the late Santonian to Maastrichtian, and episodic sedimentation produced a thick succession (>4 km) of complexly intertonguing shelf and submarine fan deposits. The basin contains a distinctly bimodal detrital zircon signature, with a major population of Cretaceous (68 to 100 Ma) zircon representing first cycle plutonic detritus eroded during active contractional tectonism within the Coast Plutonic Complex. A smaller population of Jurassic and Cretaceous zircon was derived from uplifted plutons and Methow basin strata to the east. A small yet distinct population of Meso- and Paleoproterozoic (1300-1800 Ma) zircon is consistently present, and is strikingly similar to that of the Mesoproterozoic Belt Supergroup from the western edge of Laurentia. These zircon data suggest that the arc system was locally breached by one or more large rivers by early Campanian time, allowing extraregional sediment from the distal back arc region to prograded northwestward into the basin.

Session No. 215

T197. Sevier to Laramide Tectonism along the Western Laurentian Margin: Sedimentologic and Stratigraphic Constraints on Cretaceous-Tertiary Magmatism, Deformation, and Orogenic Exhumation
Tuesday, 29 October 2013: 8:00 AM-12:00 PM
Room 203 (Colorado Convention Center)
Geological Society of America Abstracts with Programs. Vol. 45, No. 7, p.517
© Copyright 2013 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: T197. Sevier to Laramide Tectonism along the Western Laurentian Margin: Sedimentologic and Stratigraphic Constraints on Cretaceous-Tertiary Magmatism, Deformation, and Orogenic Exhumation
<< Previous Abstract | Next Abstract >>