The Cowichan fold and thrust system, Vancouver Island, southwestern British Columbia

England, T.D.J.; Calon, T.J.

doi:10.1130/0016-7606(1991)103<0336:tcfats>2.3.co;2

Cited by 44 publications

(33 citation statements)

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“…The oldest previously recognized evidence of tectonic deformation of the Nanaimo rocks is that related to the southwest-verging Cowichan fold and thrust belt of Eocene age ( Fig. 2; England and Calon 1991).…”

Section: Nanaimo Groupmentioning

confidence: 97%

“…Lithology and age of the Spieden Formation suggest a possible correlation with the Nooksack Group (Brandon et al 1988), but this connection is not supported (although not disproven) by comparison of detrital zircon age distributions in the two units ). Vance (1975), , Brandon et al (1988), England and Calon (1991), Tabor (1994), Tabor et al (2003).…”

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

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Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Brown

2012

Can. J. Earth Sci.

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The San Juan Islands -northwest Cascades thrust system in Washington and British Columbia is composed of previously accreted terranes now assembled as four broadly defined composite nappes stacked on a continental footwall of Wrangellia and the Coast Plutonic Complex. Emplacement ages of the nappe sequence are interpreted from zircon ages, field relations, and lithlogies, to young upward. The basal nappe was emplaced prior to early Turonian time (∼93 Ma), indicated by the occurrence of age-distinctive zircons from this nappe in the Sidney Island Formation of the Nanaimo Group. The emplacement age of the highest nappe in the thrust system postdates 87 Ma detrital zircons within the nappe. The nappes bear high-pressure -low-temperature (HP-LT) mineral assemblages indicative of deep burial in a thrust wedge; however, several features indicate that metamorphism occurred prior to nappe assembly: metamorphic discontinuities at nappe boundaries, absence of HP-LT assemblages in the footwall to the nappe pile, and absence of significant unroofing detritus in the Nanaimo Group. A synorogenic relationship of the thrust system to the Nanaimo Group is evident from mutually overlapping ages and by conglomerates of Nanaimo affinity that lie within the nappe pile. From the foregoing relations, and broader Cordilleran geology, the tectonic history of the nappe terranes is interpreted to involve initial accretion and subduction-zone metamorphism south of the present locality, uplift and exhumation, orogen-parallel northward transport of the nappes as part of a forearc sliver, and finally obduction at the present site over the truncated south end of Wrangellia and the Coast Plutonic Complex.Résumé : Le système de chevauchement formé par l'archipel San Juan et le nord-ouest de la chaîne des Cascades dans l'état de Washington et la province de la Colombie-Britannique est composé de terranes anciennement accrétés et qui sont maintenant assemblés, au sens large, en quatre nappes composites empilées sur l'éponte inférieure continentale de la Wrangellie et du complexe plutonique côtier. Les âges de la mise en place de la séquence des nappes ont été détermi-nés à partir d'âges de zircons, de relations sur le terrain et des lithologies; ils sont plus jeunes vers le haut. La nappe à la base a été mise en place avant le Turonien précoce (∼93 Ma), ce qui est indiqué par la présence de zircons à âge distinctif provenant de cette nappe dans la Formation de Sidney Island du Groupe de Nanaimo. L'âge de la mise en place de la nappe supérieure dans le système de chevauchement est plus tardif que les zircons détritiques âgés de 87 Ma dans cette nappe. Les nappes comportent des assemblages de minéraux de haute pression -basse température (HP-BT) indiquant un enfouissement profond dans un prisme de chevauchement; toutefois, plusieurs caractéristiques indiquent que le métamorphisme est survenu avant l'assemblage de la nappe : des discordances métamorphiques à la limite des nappes, l'absence d'assemblages HP-BT dans l'éponte inférieure de l'empilement d...

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Section: Nanaimo Groupmentioning

confidence: 97%

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Brown

2012

Can. J. Earth Sci.

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“…Regardless of its origin, the Nanaimo Basin received a continuous supply of zircon‐rich sediment from the adjacent arc during deposition of Nanaimo Group strata (Van der Heyden, ; Mustard, ; Matthews et al ., ). Lateral strike‐slip movement displaced Nanaimo Group deposits northward, and subsequent Eocene compression exposed them in a fold and thrust belt on Vancouver Island and the Gulf Islands in south‐western British Columbia, Canada (England & Calon, ; Mustard, ; Irving et al ., ; Monger & Price, ; Ward et al ., ; Mahoney et al ., ; Matthews et al ., ; Fig. B).…”

Section: Study Area and Geological Settingmentioning

confidence: 99%

Tectonically controlled initiation of contemporaneous deep‐water channel systems along a Late Cretaceous continental margin, western British Columbia, Canada

et al. 2018

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Submarine channel-systems are globally prevalent on continental margins and their deposits record the transfer of significant volumes of sediment from continental catchments to deep-water environments. These deposits contain signals of past events that can provide critical insight into the geological history of an area, including the long-term (>1 Ma) controls on sedimentation. Well-exposed outcrops of the Late Cretaceous Nanaimo Group, British Columbia, Canada, provide an opportunity to investigate long-term sediment-routing in a tectonically active setting. This study combines detrital zircon geochronology with stratigraphic analysis to establish a robust, basin-wide palaeogeographic framework that constrains the timing and distribution of coarse-grained sediment transport and deposition in the Nanaimo forearc basin. Three south-west trending submarine conduits are documented along a 135 km long strike-oriented transect, parallel to the north-west/south-east trending basin. Composite conduit deposits are 350 to 700 m thick, 4 to 16 km wide, and record substantial delivery of coarsegrained detritus (up to boulder-sized clasts) within submarine channel-lev ee systems. Maximum depositional ages derived from detrital zircon datasets constrain contemporaneous sediment transfer and deposition at each conduit location, which spanned between 73Á5 AE 1Á3 Ma to 69Á1 AE 1Á1 Ma around the Campanian-Maastrichtian boundary. Submarine conduits are spaced at 40 km and 70 km, and were likely connected to fluvial drainage systems sourced in uplifted catchments. Widespread, coarse-grained deposits suggest that surface uplift associated with concurrent regional events (such as deformation and/or magma emplacement) along the North American margin may have promoted sediment delivery to the deep-water basin. Comparisons to modern and ancient analogues support palaeogeographic interpretations, as well as the interpretation that pervasive coarse-grained deep-water sediment delivery was linked to tectonic activity. The integrated stratigraphicgeochronological approach used provides unique insight into the influence of regional tectonics on continental margin physiography and the nature of deep-water sediment dispersal.

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“…The eastern extent of Wrangellia rocks and the nature of the contact with the rocks of the Coast Belt may vary along the boundary between the Insular and Coast belts [ Clowes et al , 1997]. The basement rocks and their sedimentary cover are involved in the deformation, and the majority of the structures are Eocene, coincident with the accretion of Pacific Rim and Crescent terranes to Wrangellia [ Engebretson et al , 1985; Clowes et al , 1987; England and Calon , 1991]. On southern Vancouver Island, the Pacific Rim terrane is separated from Wrangellia by the San Juan and Survey Mountain faults (Figure 2).…”

Section: Geology and Tectonicsmentioning

confidence: 99%

Upper crustal structure of southwestern British Columbia from the 1998 Seismic Hazards Investigation in Puget Sound

et al. 2004

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[1] This paper applies nonlinear three-dimensional travel time tomography to refraction data recorded during the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) to derive the first large-scale, high-resolution upper crustal velocity model for southwestern British Columbia. A minimum structure P wave velocity model is constructed using 175,000 first arrival travel times picked from data recorded by 58 temporary onshore stations. The model details forearc crustal structures related to terrane accretion and subsequent basin formation to a depth of about 10 km. The Metchosin igneous complex

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The Cowichan fold and thrust system, Vancouver Island, southwestern British Columbia

Cited by 44 publications

References 0 publications

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Tectonically controlled initiation of contemporaneous deep‐water channel systems along a Late Cretaceous continental margin, western British Columbia, Canada

Upper crustal structure of southwestern British Columbia from the 1998 Seismic Hazards Investigation in Puget Sound

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