Journal article
Kinematics and timing of shear zone deformation in the western Coast Belt: evidence for mid-Cretaceous orogen-parallel extension
Journal of Structural Geology, Vol.68, pp.273-299
11/2014
DOI: 10.1016/j.jsg.2014.05.026
Abstract
Northwest-striking sinistral shear zones characterize mid-Cretaceous deformation in the western Coast Belt south of Prince Rupert in north coastal British Columbia. Structurally focused mapping and geochronology have revealed a component of lateral extension to this deformation. General flow characteristics of the shear zones are identified by comparison of fabric patterns to published models for fabric development in shear zones. U–Pb ages from synkinematic dykes constrain motion on northwest-striking sinistral transpressional shear zones, including the Useless, Barrett and Salt Lagoon shear zones, to ca. 104–96 Ma, and dextral transpression on the north-striking Telegraph Passage shear zone to ca. 97 Ma. The geometry, kinematics, and coeval nature of these shear zones suggest that they formed in part as a ductile conjugate set. The orientation of these conjugate sets indicates ENE–WSW (orogen perpendicular) shortening and NNW–ESE (orogen parallel) extension. The conjugate shear zones merge together into the Grenville Channel shear zone, a sinistral transpressional shear zone with high strike-parallel stretch indicating the same strain field. This local strain regime is consistent with large-scale mid-Cretaceous tectonic escape as proposed for the northern Cordillera at that time, expressed in coeval sinistral faulting in the Coast Belt and dextral faulting in the northern Omineca belt. •A structural and geochronological study of the Coast Belt south of Prince Rupert.•Structures from Coast Belt indicate mid-Cretaceous orogen parallel extension.•Sinistral and dextral transpressional shear zones form conjugate set.•Evidence supports mid-Cretaceous tectonic escape in the northern Cordillera.
Details
- Title: Subtitle
- Kinematics and timing of shear zone deformation in the western Coast Belt: evidence for mid-Cretaceous orogen-parallel extension
- Creators
- Joel J Angen - Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, CanadaCees R Van Staal - Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, CanadaShoufa Lin - Department of Earth and Environmental Sciences, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, CanadaJoAnne L Nelson - British Columbia Geological Survey, 1810 Blanshard Street, Victoria, British Columbia V8W 9N3, CanadaJ. Brian Mahoney - Department of Geology, Philips Science Hall 157, University of Wisconsin-Eau Claire, Eau Claire, WI 54702-4004, USADonald W Davis - Department of Earth Sciences, University of Toronto, 22 Russell St., Toronto, Ontario M5S 3B1, CanadaWilliam C McClelland - Department of Earth and Environmental Sciences, 121 Trowbridge Hall, University of Iowa, Iowa City, IA 52242, USA
- Resource Type
- Journal article
- Publication Details
- Journal of Structural Geology, Vol.68, pp.273-299
- Publisher
- Elsevier Ltd
- DOI
- 10.1016/j.jsg.2014.05.026
- ISSN
- 0191-8141
- eISSN
- 1873-1201
- Grant note
- DOI: 10.13039/501100000159, name: Natural Resources Canada
- Language
- English
- Date published
- 11/2014
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983983659302771
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