The architecture of oceanic plateaus revealed by the volcanic stratigraphy of the accreted Wrangellia oceanic plateau

Greene, Andrew S.

doi:10.1130/ges00212.s11

Cited by 20 publications

(42 citation statements)

References 53 publications

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“…The lack of a distinct Bouguer gravity anomaly associated with the uplift (Figure b) is due to the fact that basement rocks landward of the QCF in both Haida Gwaii and southeastern Alaska have high density regardless of their age of emplacement. The older Wrangellia terrane rocks on Haida Gwaii are basalt flows and sedimentary rocks (e.g., Greene et al, ), whereas the northern third of Haida Gwaii is covered by the 35 to 20‐Ma Massett basalt flows (e.g., Hyndman & Hamilton, ). High‐density basement rocks also underlie the shelf off southeastern Alaska, which are Paleozoic Alexander terrane meta‐volcanic and meta‐sedimentary rocks with granodiorite intrusions (Gehrels & Saleeby, ).…”

Section: Accommodation Of the Shortening Componentmentioning

confidence: 99%

“…Possible solutions to this mechanical problem include an upper crust with alternating elastic properties under Haida Gwaii and ductile lower crust, which can both provide reduced resistance to shear. Thick (~8‐km total thickness) outcrops of horizontal to subhorizontal units of alternate composition (limestones, intrusives, mafic sills, and massive basalts) of Wranglia terrane are exposed in Alaska and British Columbia and underlie Haida Gwaii (Coney et al, ; Greene et al, ). Horizontal reflectors are observed within the crust underlying Hecate Strait (Spence & Asudeh, ), and receiver function analysis shows two crustal reflectivity peaks under Haida Gwaii (Bustin et al, ).…”

Section: Accommodation Of the Shortening Componentmentioning

confidence: 99%

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Deformation of the Pacific/North America Plate Boundary at Queen Charlotte Fault: The Possible Role of Rheology

et al. 2018

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The Pacific/North America (PA/NA) plate boundary between Vancouver Island and Alaska is similar to the PA/NA boundary in California in its kinematic history and the rate and azimuth of current relative motion, yet their deformation styles are distinct. The California plate boundary shows a broad zone of parallel strike slip and thrust faults and folds, whereas the 49‐mm/yr PA/NA relative plate motion in Canada and Alaska is centered on a single, narrow, continuous ~900‐km‐long fault, the Queen Charlotte Fault (QCF). Using gravity analysis, we propose that this plate boundary is centered on the continent/ocean boundary (COB), an unusual location for continental transform faults because plate boundaries typically localize within the continental lithosphere, which is weaker. Because the COB is a boundary between materials of contrasting elastic properties, once a fault is established there, it will probably remain stable. We propose that deformation progressively shifted to the COB in the wake of Yakutat terrane's northward motion along the margin. Minor convergence across the plate boundary is probably accommodated by fault reactivation on Pacific crust and by an eastward dipping QCF. Underthrusting of Pacific slab under Haida Gwaii occurs at convergence angles >14°–15° and may have been responsible for the emergence of the archipelago. The calculated slab entry dip (5°–8°) suggests that the slab probably does not extend into the asthenosphere. The PA/NA plate boundary at the QCF can serve as a structurally simple site to investigate the impact of rheology and composition on crustal deformation and the initiation of slab underthrusting.

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Section: Accommodation Of the Shortening Componentmentioning

confidence: 99%

Section: Accommodation Of the Shortening Componentmentioning

confidence: 99%

Deformation of the Pacific/North America Plate Boundary at Queen Charlotte Fault: The Possible Role of Rheology

et al. 2018

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“…The Insular Belt, comprising the Alexander and Wrangellia terranes, forms the westernmost portion of the Canadian Cordillera (Figure ) [ Monger et al ., ]. The Wrangellia terrane is composed of Paleozoic to Jurassic, volcanic, sedimentary, and plutonic rocks [ Mustard , ; Greene et al ., ]. Jurassic to Cretaceous subduction beneath the western margin of Wrangellia lead to the formation of a volcanic arc, the Coast Belt, which intruded the eastern and western edges of the Insular and Intermontane belts, respectively (Figure ).…”

Section: Nanaimo Group Geological Settingmentioning

confidence: 99%

“…Metavolcanic, metasedimentary, and plutonic rocks into which the CPC intruded are Triassic to Cretaceous in age [ Friedman and Armstrong , ]. Likewise, the oldest parts of Wrangellia on Vancouver Island are Paleozoic volcanic and sedimentary rocks of the Sicker Group [ Brandon et al ., ; Greene et al ., ]. As such, Proterozoic zircon populations in Maastrichtian rocks must derive from source areas to the east of the CPC.…”

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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“…Oceanic plateaus are ultramafic‐mafic, large igneous provinces that reach thicknesses of ~35 km (e.g., Ontong Java Plateau) [ Mahoney and Spencer , ; Neal et al , ], are buoyant relative to normal oceanic lithosphere of the same age (due to the presence of a thickened basaltic crust), and can reach widths of more than 1000 km (Figure ). A majority of U‐Pb and 40 Ar/ 39 Ar ages of the Caribbean Plateau span 92–88 Ma [ Kerr et al , ; Sinton et al , ; Vallejo et al , , ; Villagómez et al , ], and 40 Ar/ 39 Ar ages of the Wrangellia Plateau (western Canada) span 230–225 Ma [ Greene et al , ]. These short time spans (≤5 Ma) are typical of other globally distributed oceanic plateaus (Figure ), indicating that they are rapidly emplaced.…”

Section: Oceanic Plateau–continent Collisionmentioning

confidence: 99%

Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust

Spikings

Simpson

2014

Tectonics

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Understanding the causes of rock and surface uplift is important because they control the location of mountain building, depocenters, and drainage characteristics and can influence climate. Here we combine previous thermochronological data with field observations to determine the amount of exhumation, rock, and surface uplift that occurs in the upper plate of Central and South American subduction zones during the collision, accretion, and subduction of oceanic plateaus and aseismic ridges. The collision of buoyant and topographically prominent oceanic plateaus and ridges can drive at least 5 km of rock uplift within 2 Ma. Uplift appears to be an immediate response to collision and is generally independent of the slab dip. The amount of rock uplift is controlled mainly by excess topography associated with the ridge (ultimately linked to buoyancy) and erosion, while it is also influenced by the strength of the subduction interface related to the presence of volcanic asperities and overpressured sediments in the subduction channel. The quantity of exhumation is strongly dependant on climate-induced erosion and the lifespan over which the topography is uplifted and supported. Sediment draining into the trench may leave the elevated ridge axis sediment starved, increasing the shear stresses at the ridge subduction interface, leading to positive feedback between ridge subduction, rock uplift, and exhumation. Trench-parallel variations in exhumation have a direct impact on exploration paradigms for porphyry-related metalliferous deposits, and it is likely that porphyry systems are completely eroded by the impingement of plateaus and aseismic ridges within temperate and tropical climates.

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The architecture of oceanic plateaus revealed by the volcanic stratigraphy of the accreted Wrangellia oceanic plateau

Cited by 20 publications

References 53 publications

Deformation of the Pacific/North America Plate Boundary at Queen Charlotte Fault: The Possible Role of Rheology

Deformation of the Pacific/North America Plate Boundary at Queen Charlotte Fault: The Possible Role of Rheology

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

Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust

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