A Paleozoic Zircon Age of the Westcoast Crystalline Complex of Vancouver Island, British Columbia

Muller, J. E.; Wanless, R. K.; Loveridge, W D

doi:10.1139/e74-169

Cited by 8 publications

(4 citation statements)

References 6 publications

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“…Early Jurassic magmatism is common throughout the Wrangellia terrane on Vancouver Island (Figure ) and is a potential source for these grains. The extensive Westcoast Crystalline Complex and Island Intrusions plutonic suites are dated between 190 and 167 Ma [ DeBari et al ., ; Canil et al ., ], and the Bonanza Group volcanics have been dated using U/Pb zircon geochronology and biostratigraphy on interbedded siliciclastic units at between 202 to 165 Ma [ Muller et al ., ; Isachsen , , ; DeBari et al ., ]. While these rocks overlap in age with Early Jurassic detrital zircon populations in the Nanaimo basin, it is unlikely that they were accessible to the sedimentary system during the Maastrichtian.…”

Section: Provenance Of the Nanaimo Groupmentioning

confidence: 99%

Detrital zircons from the Nanaimo basin, Vancouver Island, British Columbia: An independent test of Late Cretaceous to Cenozoic northward translation

et al. 2017

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The development of the Cordilleran orogen of western North American is disputed despite a century of study. Paleomagnetic observations require large‐scale dextral displacements of crustal fragments along the western margin of North America, from low latitudes to moderate latitudes during the Cretaceous‐Paleogene. A lack of corroborating geological evidence for large‐scale (>1500 km) displacements has prevented the widespread integration of paleomagnetic data into most contemporary tectonic models for the margin. Here we use detrital zircons from the Nanaimo basin, southwestern British Columbia, Canada as an independent test of its Late Cretaceous paleogeographic position. We compare 4310 detrital zircon U/Pb dates from 16 samples to potential source areas in western North America to test hypothesized northern and southern Late Cretaceous paleogeographic positions. Our detrital zircon data suggest that sediment in the Nanaimo basin derives from either a geographically restricted portion of the Belt‐Purcell basin or the Mojave‐Sonoran region of southwestern North America. A paleogeographic position for the basin adjacent to the Mojave‐Sonoran region is preferred as it is consistent with the paleomagnetic results, but further geological, isotopic, or geophysical data are required to rule out a Belt‐Purcell source.

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Section: Provenance Of the Nanaimo Groupmentioning

confidence: 99%

Detrital zircons from the Nanaimo basin, Vancouver Island, British Columbia: An independent test of Late Cretaceous to Cenozoic northward translation

et al. 2017

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“…The midcrustal section is preserved in batholiths and felsic intrusions of the Island Intrusive Suite (Figure 1) [35,36], which have yielded U-Pb zircon crystallization ages from ca.175 to 168 Ma, 40 Ar- 39 Ar cooling ages of ca.176 and 166 Ma, and a K-Ar age range of 181-152 Ma [46,47]. The Bonanza Group consists of~2,500 meters of lava flows, pyroclastic flows, thin interbedded sedimentary units, and minor low-grade metamorphic rock that are interpreted to be the volcanic equivalents of the Island Intrusions (Figure 1) [34,36,[48][49][50]. These rocks have yielded a U-Pb zircon age range from ca.…”

Section: Arc Migration In the Southern Wrangellia Arc Systemmentioning

confidence: 99%

U-Pb and Hf Analyses of Detrital Zircons from Paleozoic and Cretaceous Strata on Vancouver Island, British Columbia: Constraints on the Paleozoic Tectonic Evolution of Southern Wrangellia

2021

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Wrangellia is a late Paleozoic arc terrane that occupies two distinct coastal regions of western Canada and Alaska. The Skolai arc of northern Wrangellia in south-central Alaska and Yukon has been linked to the older, adjacent Alexander terrane by shared Late Devonian rift-related gabbros and also by Late Pennsylvanian postcollisional plutons. Late Devonian to Early Permian Sicker arc rocks of southern Wrangellia are exposed in uplifts on Vancouver Island, southwestern British Columbia, surrounded by younger strata and lacking physical connections to other terranes. Utilizing the detrital zircon record of Paleozoic and Cretaceous sedimentary rocks, we provide insight into the magmatic and depositional evolution of southern Wrangellia and its relationships to both northern Wrangellia and the Alexander terrane. 1422 U-Pb LA-ICPMS analyses from the Fourth Lake Formation (Mississippian–Permian) reveal syndepositional Carboniferous age peaks (344, 339, 336, 331, and 317 Ma), sourced from the Sicker arc of southern Wrangellia. These populations overlap in part known ages of volcanism, but the Middle Mississippian cumulative peak (337 Ma) documents a previously unrecognized magmatic episode. Paleozoic detrital zircons exhibit intermediate to juvenile ƐHft values between +15 and +5, indicating that southern Wrangellia was not strictly built on primitive oceanic crust, but instead on transitional crust with a small evolved component. The Fourth Lake samples yielded 49 grains (3.4% of the total grains analyzed) with ages between 2802 Ma and 442 Ma, and with corresponding ƐHft values ranging from +13 to -20. In age—ƐHft space, these grains fall within the Alexander terrane array. They were probably derived from sedimentary rocks in the basement of the Sicker arc. By analogy with northern Wrangellia, this basement incorporated rifted fragments of the Alexander terrane margin as the combined Sicker-Skolai arc system advanced ocean-ward due to slab rollback in Late Devonian to Early Mississippian time. Ultimately, data from detrital zircons preserved in the Fourth Lake Formation provides significant information allowing for an updated tectonic model of Paleozoic Wrangellia.

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“…1). The Bonanza Group represents arc volcanism comprising ~2,500 meters of lava flows, pyroclastic flows, thin interbedded sedimentary units, and minor low-grade metamorphic rock that have been intruded by the Island Intrusions (Muller, 1974;Nixon et al, 1994;Nixon and Orr, 2006;Paulson, 2010;Nixon et al, 2011) (Fig. 1).…”

Section: The Bonanza Groupmentioning

confidence: 99%

“…1). The WCC yields various U-Pb zircon ages ranging from 190-177 Ma (Isachsen, 1987;DeBari et al, 1999), a Rb-Sr age of 151 Ma (Isachsen, 1987), and K-Ar ages of 172 and 163 Ma (Wanless et al, 1974;Isachsen, 1987). The Island Intrusions yield U-Pb zircon crystallization ages from 175-168 Ma, 40 Ar-39 Ar cooling ages of 176 and 166 Ma, and a K-Ar age range of 181-152 Ma (Carson, 1973;Muller, 1977), whereas the Bonanza Group yields a U-Pb zircon crystallization age range from 202-165 Ma (Friedman and Nixon, 1995;Debari et al, 1999).…”

Section: The Bonanza Groupmentioning

confidence: 99%

U-Pb and Hf Isotopic Analysis of Detrital Zircons From Paleozoic and Cretaceous Strata of Southern Vancouver Island, British Columbia

Alberts¹

2018

Geological Society of America Abstracts With Programs

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Wrangellia, an exotic arc terrane to North America, is interpreted to have been constructed near the margin of the Paleo-Arctic and Paleo-Pacific during middle-late Paleozoic time, before finally accreting to the western margin of North America during Late Jurassic to Early Cretaceous time. Utilizing the detrital zircon record of Paleozoic sedimentary rocks and Cretaceous basin fill we can provide further insight into the magmatic and depositional evolution of southern Wrangellia. 1422 U-Pb LA-ICPMS analyses from five samples of the Fourth Lake Formation in the Carboniferous Buttle Lake Group were performed. 1055 U-Pb LA-ICPMS analyses from four samples of the Comox formation within the Cretaceous Nanaimo Group were acquired in order to provide a broader sampling of the Lower Mesozoic-Paleozoic rocks of Vancouver Island. U-Pb analyses within the Fourth Lake Formation reveal prominent Carboniferous age peaks (344, 339, 336, 331, and 317 Ma), with minor pre-400 Ma grains from adjacent terranes of Paleo-Arctic origin. Paleozoic detrital zircons exhibit juvenile, with ƐHf (t) values between +15 and +5. U-Pb analyses of Nanaimo Group sedimentary rocks reveal dominant peak ages at 341, 195, 167, and 86 Ma. All major populations yield juvenile epsilon ƐHf (t) values in the range of +15 to +6. The detrital zircon U-Pb geochronologic and Hf isotope data in this study suggest that sediment from the Fourth Lake Formation was derived mainly from bimodal magmatism within the Paleozoic southern Wrangellia arc system as well as minor 6 contributions of recycled detritus from the adjacent Alexander Terrane. Hf isotope data from the Comox Formation indicate that Triassic and Jurassic igneous rocks of the Bonanza Arc, and Late Jurassic-Early Cretaceous sources from the central Coast Mountains Batholith (CMB), are highly juvenile. This new geochronologic and geochemical data set contributes to a new tectonic model for the Paleozoic Southern Wrangellia Arc system from Late Devonian to Early Permian time and reveals, during Cretaceous time, very locally derived detritus was deposited in sedimentary basins along the inboard margin of Wrangellia.

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A Paleozoic Zircon Age of the Westcoast Crystalline Complex of Vancouver Island, British Columbia

Cited by 8 publications

References 6 publications

Detrital zircons from the Nanaimo basin, Vancouver Island, British Columbia: An independent test of Late Cretaceous to Cenozoic northward translation

Detrital zircons from the Nanaimo basin, Vancouver Island, British Columbia: An independent test of Late Cretaceous to Cenozoic northward translation

U-Pb and Hf Analyses of Detrital Zircons from Paleozoic and Cretaceous Strata on Vancouver Island, British Columbia: Constraints on the Paleozoic Tectonic Evolution of Southern Wrangellia

U-Pb and Hf Isotopic Analysis of Detrital Zircons From Paleozoic and Cretaceous Strata of Southern Vancouver Island, British Columbia

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