Journal articles: 'Geology – British Columbia – Gambier Island'

1

Gabelman, John W., and William M. Hanusiak. "Gold Occurrence at Island Copper Mine, British Columbia." Journal of Geochemical Exploration 25, no. 1-2 (March 1986): 252. http://dx.doi.org/10.1016/0375-6742(86)90048-8.

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CLAGUE, JOHN J., and PETER T. BOBROWSKY. "Tsunami deposits beneath tidal marshes on Vancouver Island, British Columbia." Geological Society of America Bulletin 106, no. 10 (October 1994): 1293–303. http://dx.doi.org/10.1130/0016-7606(1994)106<1293:tdbtmo>2.3.co;2.

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Cosma, T., and I. L. Hendy. "Pleistocene glacimarine sedimentation on the continental slope off Vancouver Island, British Columbia." Marine Geology 255, no. 1-2 (September 2008): 45–54. http://dx.doi.org/10.1016/j.margeo.2008.07.001.

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Welker, Richard R. "The Geochemical Environment of Westmin Resources Buttle Lake Mine, Vancouver Island, British Columbia." Journal of Geochemical Exploration 25, no. 1-2 (March 1986): 254–55. http://dx.doi.org/10.1016/0375-6742(86)90052-x.

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Arksey, Ron, and Doug VanDine. "Example of a debris-flow risk analysis from Vancouver Island, British Columbia, Canada." Landslides 5, no. 1 (November 28, 2007): 121–26. http://dx.doi.org/10.1007/s10346-007-0105-0.

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TERABAYASHI, M. "Compositional evolution in Ca-amphibole in the Karmutsen metabasites, Vancouver Island, British Columbia, Canada." Journal of Metamorphic Geology 11, no. 5 (September 1993): 677–90. http://dx.doi.org/10.1111/j.1525-1314.1993.tb00180.x.

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James, Thomas, Evan J. Gowan, Ian Hutchinson, John J. Clague, J. Vaughn Barrie, and Kim W. Conway. "Sea-level change and paleogeographic reconstructions, southern Vancouver Island, British Columbia, Canada." Quaternary Science Reviews 28, no. 13-14 (June 2009): 1200–1216. http://dx.doi.org/10.1016/j.quascirev.2008.12.022.

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Hungr, O., and S. G. Evans. "An example of a peat flow near Prince Rupert, British Columbia." Canadian Geotechnical Journal 22, no. 2 (May 1, 1985): 246–49. http://dx.doi.org/10.1139/t85-034.

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Peat flows, bog flows, or bog bursts consist of a rapid downhill movement of masses of saturated peat. Although this process has been documented from peatlands in other parts of the world, the slope movement described here is the first to be reported from Canadian peatlands. The peat flow took place on the east coast of Kaien Island, near Prince Rupert, British Columbia, and was initiated by a slump in a peat spoil pile. It involved the sudden mobilization of a strip of in situ peat 210 m long and approximately 20 m wide. The peat was fibrous, rich in roots, and had a moisture content of approximately 240%. The flow demonstrates the high potential mobility of natural peat covers and the role of undrained loading in effecting movement of slopes as low as 5°. Key words: peat, flow slide, peat flow, northeast British Columbia.

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Bustin, Amanda M. M., Ron M. Clowes, James W. H. Monger, and J. Murray Journeay. "The southern Coast Mountains, British Columbia: New interpretations from geological, seismic reflection, and gravity data." Canadian Journal of Earth Sciences 50, no. 10 (October 2013): 1033–50. http://dx.doi.org/10.1139/cjes-2012-0122.

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The southern Coast Mountains of British Columbia are characterized by voluminous plutonic and gneissic rocks of mainly Middle Jurassic to Eocene age (the Coast Plutonic Complex), as well as metamorphic rocks, folds, and thrust and reverse faults that mostly diverge eastward and westward from an axis within the present mountains, and by more localized Eocene and younger normal faults. In the southeastern Coast Mountains, mid-Cretaceous and younger plutons intrude Bridge River, Cadwallader, and Methow terranes and overlap Middle Jurassic through Early Cretaceous marine clastic rocks of the Tyaughton–Methow basin. The combination of geological data with new or reanalyzed geophysical data originating from Lithoprobe and related studies enables revised structural interpretations to be made to 20 km depth. Five seismic profiles show very cut-up and chaotic reflectivity that probably represents slices and segments of different deformed and rearranged rock assemblages. Surface geology, seismic interpretations, physical properties, and gravity data are combined in two profiles across the Coast Mountains to generate two new 2-D density models that are interpreted in terms of the geological units. The western part of the southern Coast Mountains consists primarily of Jurassic to mid-Cretaceous plutons to depths of 20 km with slices of Wrangellia (in the west) and Early Cretaceous volcanic and sedimentary rocks (Gambier group) in the upper 10 km. The eastern part, east of the Owl Creek fault, consists of slices of Cadwallader and Bridge River terranes and Tyaughton–Methow basin strata with limited slices of plutonic rocks at depths less than 10 km. Below that, Eocene and Late Cretaceous plutons dominate for another 10 km.

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Evans, Stephen G. "The 1946 Mount Colonel Foster rock avalanche and associated displacement wave, Vancouver Island, British Columbia." Canadian Geotechnical Journal 26, no. 3 (August 1, 1989): 447–52. http://dx.doi.org/10.1139/t89-057.

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The 1946 Vancouver Island earthquake (M = 7.2) triggered a rock avalanche from the north face of Mount Colonel Foster, central Vancouver Island, British Columbia. Approximately 1.5 × 106 m3 of Triassic volcaniclastic rocks detached from between el. 1965 m and el. 1600 m. Although just over half of this volume was deposited in the upper part of the track above el. 1080 m, approximately 0.7 × 106 m3 descended the lower part of the track and entered the waters of Landslide Lake at el. 890 m. The resultant displacement wave ran up a maximum vertical distance of 51 m on the opposite shore and the wave crest was about 29 m high when it spilled over the lip of the lake. Water displaced during the event destroyed forest in the upper reaches of the Elk River valley up to 3 km from Landslide Lake. The wave at Landslide Lake is comparable to other waves generated by similar magnitude rock avalanches in Peru and Norway and it is the largest recorded in the Canadian Cordillera. The case history illustrates the conditions where substantial damage may be caused by a rock avalanche well beyond the limits of its debris when it produces a landslide-generated wave in the mountainous terrain of the Cordillera. Key words: rock avalanche, earthquake-induced landslides, landslide-generated waves, mountains.

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Brideau, Marc-André, Doug Stead, Thomas H. Millard, and Brent C. Ward. "Field characterisation and numerical modelling of debris avalanche runout on Vancouver Island, British Columbia, Canada." Landslides 16, no. 5 (February 12, 2019): 875–91. http://dx.doi.org/10.1007/s10346-019-01141-7.

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Barrie, J. Vaughn, and Kim W. Conway. "Coastal to offshore submarine channel sediment transport system: Savary Island, British Columbia, Canada." Geo-Marine Letters 39, no. 6 (November 6, 2019): 435–46. http://dx.doi.org/10.1007/s00367-019-00602-1.

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13

Isachsen, Clark E. "Geology, geochemistry, and cooling history of the Westcoast Crystalline Complex and related rocks, Meares Island and vicinity, Vancouver Island, British Columbia." Canadian Journal of Earth Sciences 24, no. 10 (October 1, 1987): 2047–64. http://dx.doi.org/10.1139/e87-194.

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The Westcoast Crystalline Complex is a belt of plutonic rocks along the west coast of Vancouver Island. It is composed mainly of heterogeneous amphibolitic country rock (Westcoast amphibolite), granitoids of trondhjemitic to gabbroic composition (Westcoast diorite), and variable mixtures of these two components (Westcoast migmatite).Although the protolith of some deformed enclaves may be Paleozoic, most of these rocks were generated in a magmatic-arc setting and intruded in Jurassic time. Major- and trace-element chemistry of the Westcoast Crystalline Complex shows a sub-alkaline tholeiitic to calc-alkaline trend.The exponential cooling curves derived for Westcoast diorites are not consistent with in situ crustal magma genesis but instead indicate that these rocks intruded relatively cool country rock.Based on age and chemistry, the Westcoast Crystalline Complex can be interpreted as the deeper crustal equivalent of the more differentiated Island Intrusions and Bonanza Volcanics. Taken together, these rocks provide a disrupted and perhaps incomplete cross section of the magmatic arc of Vancouver Island.Reconnaissance of the Wark–Colquitz Complex of southern Vancouver Island shows it to be essentially indistinguishable in petrography, chemistry, and age from the Westcoast Crystalline Complex, and a similar history is inferred.A calc-alkaline chemistry and rapid initial cooling also characterize a Catface Intrusion dated at 41 Ma. This is again compatible with arc magmatism, but its proximity to the coeval trench is enigmatic.

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Robinson, Michelle, Colin I. Godwin, and Clifford R. Stanley. "Geology, lithogeochemistry, and alteration of the Battle volcanogenic massive sulfide zone, Buttle Lake mining camp, Vancouver Island, British Columbia." Economic Geology 91, no. 3 (May 1, 1996): 527–48. http://dx.doi.org/10.2113/gsecongeo.91.3.527.

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15

Tochilin, Clare J., George E. Gehrels, JoAnne Nelson, and J. Brian Mahoney. "U-Pb and Hf isotope analysis of detrital zircons from the Banks Island assemblage (coastal British Columbia) and southern Alexander terrane (southeast Alaska)." Lithosphere 6, no. 3 (June 2014): 200–215. http://dx.doi.org/10.1130/l338.1.

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16

Goetz, J. N., R. H. Guthrie, and A. Brenning. "Forest harvesting is associated with increased landslide activity during an extreme rainstorm on Vancouver Island, Canada." Natural Hazards and Earth System Sciences 15, no. 6 (June 22, 2015): 1311–30. http://dx.doi.org/10.5194/nhess-15-1311-2015.

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Abstract. Safe operations of forest practices in mountainous regions require effective development planning to mitigate hazards posed by landslides. British Columbia, Canada, has for the past 2 decades implemented landslide risk management policies aimed at reducing the impacts of the forestry industry on landslides. Consequently, it is required that timber harvesting sites be evaluated for their potential or existing impacts on terrain stability. Statistical landslide susceptibility modelling can enhance this evaluation by geographically highlighting potential hazardous areas. In addition, these statistical models can also improve our understanding of regional landslide controlling factors. The purpose of this research was to explore the regional effects of forest harvesting activities, topography, precipitation and geology on landslides initiated during an extreme rainfall event in November 2006 on Vancouver Island, British Columbia. These effects were analyzed with a nonparametric statistical method, the generalized additive model (GAM). Although topography was the strongest predictor of landslide initiation, low density forest interpreted as regrowth areas and proximity to forest service roads were jointly associated with a 6- to 9-fold increase in the odds of landslide initiation, while accounting for other environmental confounders. This result highlights the importance of continuing proper landslide risk management to control the effects of forest practices on landslide initiation.

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Goetz, J. N., R. H. Guthrie, and A. Brenning. "Forest harvesting is associated with increased landslide activity during an extreme rainstorm on Vancouver Island, Canada." Natural Hazards and Earth System Sciences Discussions 2, no. 8 (August 27, 2014): 5525–74. http://dx.doi.org/10.5194/nhessd-2-5525-2014.

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Abstract. Safe operations of forest practices in mountainous regions require effective development planning to mitigate hazards posed by landslides. British Columbia, Canada, has for the past two decades implemented landslide risk management policies aimed at reducing the impacts of the forest industry on landslides; it is required that timber harvesting sites are evaluated for their potential or existing impacts on terrain stability. Statistical landslide susceptibility modelling can enhance this evaluation by geographically highlighting potential hazardous areas. In addition, these statistical models can also improve our understanding of regional landslide controlling factors. The purpose of this research was to explore the regional effects of forest harvesting activities, topography, precipitation and geology on landslides initiated during an extreme rainfall event in November 2006 on Vancouver Island, British Columbia. These effects were analysed with a nonparametric statistical method, the generalized additive model (GAM). Although topography was the strongest predictor of landslide initiation, low density forest interpreted as regrowth areas and proximity to forest service roads were jointly associated with a six- to nine-fold increase in the odds of landslide initiation, while accounting for other environmental cofounders. This result highlights the importance of continuing proper landslide risk management to control the effects of forest practices on landslide initiation.

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18

Clague, John J., Peter T. Bobrowsky, and Ian Hutchinson. "A review of geological records of large tsunamis at Vancouver Island, British Columbia, and implications for hazard." Quaternary Science Reviews 19, no. 9 (May 2000): 849–63. http://dx.doi.org/10.1016/s0277-3791(99)00101-8.

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19

Huntley, D. H., P. T. Bobrowsky, and J. J. Clague. "Ocean Drilling Program Leg 169S: surficial geology, stratigraphy and geomorphology of the Saanich Inlet area, southeastern Vancouver Island, British Columbia." Marine Geology 174, no. 1-4 (March 2001): 27–41. http://dx.doi.org/10.1016/s0025-3227(00)00140-7.

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20

Bazett, D. J., and N. R. McCammon. "Foundations of the Annacis cable-stayed bridge." Canadian Geotechnical Journal 23, no. 4 (November 1, 1986): 458–71. http://dx.doi.org/10.1139/t86-076.

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A new highway crossing of the Fraser River at Annacis Island near Vancouver, British Columbia, is currently under construction. It involves a major cable-stayed bridge with a main span of 465 m. Support for the bridge is provided by piles driven into dense overconsolidated Quaternary sediments: on the south bank they are found essentially at ground surface while on the north (Annacis Island) side they are encountered at a depth of 80–85 m overlain by sequences of weak deltaic and alluvial materials. This paper describes the geotechnical investigation for the bridge and describes the design of six foundations including those for the two main piers. The north main pier is founded on unusually deep pipe piles about 85 m long. Key words: bridge, case history, earthquake, geological investigations, liquefaction, negative skin friction, pile, settlement analysis, site investigation.

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21

Clowes, Ron M., David J. Baird, and Sonya A. Dehler. "Crustal structure of the Cascadia subduction zone, southwestern British Columbia, from potential field and seismic studies." Canadian Journal of Earth Sciences 34, no. 3 (March 1, 1997): 317–35. http://dx.doi.org/10.1139/e17-028.

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The northern Cascadia subduction zone is a region of convergence between the oceanic Explorer and northern Juan de Fuca plates and the continental North American plate. Potential field and new seismic reflection data coupled with previous seismic results and geology enable derivation of a series of density – magnetic susceptibility cross sections and a block density model from the ocean basin to the volcanic arc from 2.5- and 3-dimensional interpretations. The lateral extent and thickness of the accreted wedge vary significantly along the zone. The narrow, metasedimentary Pacific Rim terrane lies immediately west of Wrangellia and extends the length of Vancouver Island, consistent with its emplacement by strike-slip faulting following the accretion of Wrangellia. The ophiolitic Crescent terrane is a narrow slice lying seaward of the Pacific Rim terrane but not extending northward beyond the Juan de Fuca plate. In this region, the Crescent terrane was emplaced in a strike-slip or obliquely convergent style during the latter stages of emplacement of Pacific Rim terrane. Below the accreted terranes, the Explorer plate is shallower than Juan de Fuca plate, resulting in a thinner crust. High-density lower crustal material lies beneath the western edge of Vancouver Island, supporting interpretations of wide-scale underplating of Wrangellia. The shape of the boundary region between Wrangellia and the Coast belt to the east varies along strike and may be controlled by properties of preexisting plutonic rocks. The low-density Coast belt plutons extend throughout most of the crust and are underlain by a lowermost crustal high-density layer, which may be indicative of fractionation accompanying magma generation.

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Lowe, C., S. A. Dehler, and B. C. Zelt. "Basin architecture and density structure beneath the Strait of Georgia, British Columbia." Canadian Journal of Earth Sciences 40, no. 7 (July 1, 2003): 965–81. http://dx.doi.org/10.1139/e03-030.

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Georgia Basin is located within one of the most seismically active and populated areas on Canada's west coast. Over the last decade, geological investigations have resolved important details concerning the basin's shallow structure and composition. Yet, until recently, relatively little was known about deeper portions of the basin. In this study, new seismic velocity information is employed to develop a 3-dimensional density model of the basin. Comparison of the calculated gravity response of this model with the observed gravity field validates the velocity model at large scales. At smaller scales, several differences between model and observed gravity fields are recognized. Analysis of these differences and correlation with independent geoscience data provide new insights into the structure and composition of the basin-fill and underlying basement. Specifically, four regions with thick accumulations of unconsolidated Pleistocene and younger sediments, which were not resolved in the velocity model, are identified. Their delineation is particularly important for studies of seismic ground-motion amplification and offshore aggregate assessment. An inconsistency between the published geology and the seismic structure beneath Texada and Lasqueti Islands in the central Strait of Georgia is investigated; however, the available gravity data cannot preferentially validate either the geologic interpretation or the seismic model in this region. We interpret a northwest-trending and relatively linear gradient extending from Savory Island in the north to Boundary Bay in the south as the eastern margin of Wrangellia beneath the basin. Finally, we compare Georgia Basin with the Everett and Seattle basins in the southern Cascadia fore arc. This comparison indicates that while a single mechanism may be controlling present-day basin tectonics and deformation within the fore arc this was not the case for most of the Mesozoic and Tertiary time periods.

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Brown, E. H. "Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia." Canadian Journal of Earth Sciences 49, no. 7 (July 2012): 796–817. http://dx.doi.org/10.1139/e2012-026.

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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.

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Deering, Robert, Trevor Bell, Donald L. Forbes, Calvin Campbell, and Evan Edinger. "Morphological characterization of submarine slope failures in a semi-enclosed fjord, Frobisher Bay, eastern Canadian Arctic." Geological Society, London, Special Publications 477, no. 1 (May 24, 2018): 367–76. http://dx.doi.org/10.1144/sp477.35.

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AbstractSubmarine slope failures in the nearshore waters of SE Baffin Island, eastern Canadian Arctic, present a challenge to coastal and seabed development. Submarine slope failures are a known geohazard in fjords in Norway, Chile, Alaska, British Columbia and elsewhere, but have received little attention in the coastal waters of Arctic Canada. Over the past 6 years, there has been a rapid expansion of multibeam echosounder (MBES) mapping in Canadian Arctic fjords, leading to the discovery of many submarine slope failures. One area that has been mapped in detail is inner Frobisher Bay. This macrotidal, seasonally ice-covered, semi-enclosed embayment has a glacially scoured bed, ice-contact deposits, including recessional moraines, and stratified glaciomarine and post-glacial silts and clays with abundant dropstones. The prevalence of submarine slope failures in the inner bay (one per 20 km2) appears to be anomalous. To date, MBES mapping has imaged at least 246 failures, ranging in size from 0.007 to 2.1 km2 and all within the glaciomarine and post-glacial succession. Morphometric analysis of these features based on high-resolution MBES bathymetry provides an insight into their spatial distribution, relative chronology, triggers and flow characteristics; factors essential to understanding the mechanisms underlying their abundance in this Canadian Arctic fjord.

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Cruwys, Liz, and Beau Riffenburgh. "Bernard Stonehouse: biologist, writer, and educator." Polar Record 38, no. 205 (April 2002): 157–69. http://dx.doi.org/10.1017/s003224740001754x.

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AbstractThis is the first in a series of biographies entitled ‘Children of the Golden Age’, the purpose of which is to describe the background and contributions of a number of significant living figures in polar research, all of whom began their scientific careers and earned their Antarctic spurs in the years following World War II. Bernard Stonehouse was born in Hull on 1 May 1926. Joining the Royal Navy in 1944, he trained as a pilot, and in 1946–50 served as meteorologist, second pilot, dog-sledger, and ultimately biologist with the Falkland Islands Dependencies Survey, mainly from Base E, Stonington Island, Antarctic Peninsula. His first biological investigation was a winter study of breeding emperor penguins. Returning to Britain in 1950 he read zoology and geology at University College, London. Doctoral research at the Edward Grey Institute of Field Ornithology and Merton College, Oxford, involved an 18-month field study of king penguins on South Georgia. Between 1960 and 1968, as senior lecturer, later reader, in zoology, at University of Canterbury, Christchurch, New Zealand, he continued Antarctic and sub-Antarctic research in McMurdo Sound and on the New Zealand southern islands. A Commonwealth Research Fellowship at the University of British Columbia, 1970–71, gave him opportunities for research in the Yukon. After developing undergraduate and postgraduate studies in environmental science at the University of Bradford, 1972–83, he joined the Scott Polar Research Institute as editor of Polar Record, thereafter forming the Institute's Polar Ecology and Management Group, and heading a long-term study on the ecological impacts of polar tourism. At SPRI he continues to combine the two factors that have always played an important part in his life: working in polar regions and communicating with the general public on issues of biology, the environment, and conservation.

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Brothers, Daniel S., Brian D. Andrews, Maureen A. L. Walton, H. Gary Greene, J. Vaughn Barrie, Nathan C. Miller, Uri ten Brink, et al. "Slope failure and mass transport processes along the Queen Charlotte Fault, southeastern Alaska." Geological Society, London, Special Publications 477, no. 1 (May 21, 2018): 69–83. http://dx.doi.org/10.1144/sp477.30.

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AbstractThe Queen Charlotte Fault defines the Pacific–North America transform plate boundary in western Canada and southeastern Alaska for c. 900 km. The entire length of the fault is submerged along a continental margin dominated by Quaternary glacial processes, yet the geomorphology along the margin has never been systematically examined due to the absence of high-resolution seafloor mapping data. Hence the geological processes that influence the distribution, character and timing of mass transport events and their associated hazards remain poorly understood. Here we develop a classification of the first-order shape of the continental shelf, slope and rise to examine potential relationships between form and process dominance. We found that the margin can be split into six geomorphic groups that vary smoothly from north to south between two basic end-members. The northernmost group (west of Chichagof Island, Alaska) is characterized by concave-upwards slope profiles, gentle slope gradients (<6°) and relatively low along-strike variance, all features characteristic of sediment-dominated siliciclastic margins. Dendritic submarine canyon/channel networks and retrogressive failure complexes along relatively gentle slope gradients are observed throughout the region, suggesting that high rates of Quaternary sediment delivery and accumulation played a fundamental part in mass transport processes. Individual failures range in area from 0.02 to 70 km2 and display scarp heights between 10 and 250 m. Transpression along the Queen Charlotte Fault increases southwards and the slope physiography is thus progressively more influenced by regional-scale tectonic deformation. The southernmost group (west of Haida Gwaii, British Columbia) defines the tectonically dominated end-member: the continental slope is characterized by steep gradients (>20°) along the flanks of broad, margin-parallel ridges and valleys. Mass transport features in the tectonically dominated areas are mostly observed along steep escarpments and the larger slides (up to 10 km2) appear to be failures of consolidated material along the flanks of tectonic features. Overall, these observations highlight the role of first-order margin physiography on the distribution and type of submarine landslides expected to occur in particular morphological settings. The sediment-dominated end-member allows for the accumulation of under-consolidated Quaternary sediments and shows larger, more frequent slides; the rugged physiography of the tectonically dominated end-member leads to sediment bypass and the collapse of uplifted tectonic features. The maximum and average dimensions of slides are an order of magnitude smaller than those of slides observed along other (passive) glaciated margins. We propose that the general patterns observed in slide distribution are caused by the interplay between tectonic activity (long- and short-term) and sediment delivery. The recurrence (<100 years) of M > 7 earthquakes along the Queen Charlotte Fault may generate small, but frequent, failures of under-consolidated Quaternary sediments within the sediment-dominated regions. By contrast, the tectonically dominated regions are characterized by the bypass of Quaternary sediments to the continental rise and the less frequent collapse of steep, uplifted and consolidated sediments.

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Brian D. Bornhold, Pierre Giresse. "Glauconitic Sediments on the Continental Shelf off Vancouver Island, British Columbia, Canada." SEPM Journal of Sedimentary Research Vol. 55 (1985). http://dx.doi.org/10.1306/212f87ab-2b24-11d7-8648000102c1865d.

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Alberts, Daniel, George E. Gehrels, and Joanne Nelson. "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." Lithosphere 2021, no. 1 (February 26, 2021). http://dx.doi.org/10.2113/2021/7866944.

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Abstract 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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ZONNEVELD, JOHN-PAUL, THOMAS F. MOS. "Abstract: Evolution Of A Barred Barrier Island Shoreface Succession: Doig, Halfway & Basal Charlie Lake Formations (Triassic), British Columbia, Canada." AAPG Bulletin 83 (1999) (1999). http://dx.doi.org/10.1306/c9ebcd15-1735-11d7-8645000102c1865d.

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30

Watt, Janet T., and Daniel S. Brothers. "Systematic characterization of morphotectonic variability along the Cascadia convergent margin: Implications for shallow megathrust behavior and tsunami hazards." Geosphere, November 20, 2020. http://dx.doi.org/10.1130/ges02178.1.

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Studies of recent destructive megathrust earthquakes and tsunamis along subduction margins in Japan, Sumatra, and Chile have linked forearc morphology and structure to megathrust behavior. This connection is based on the idea that spatial variations in the frictional behavior of the megathrust influence the tectono-morphological evolution of the upper plate. Here we present a comprehensive examination of the tectonic geomorphology, outer wedge taper, and structural vergence along the marine forearc of the Cascadia subduction zone (offshore northwestern North America). The goal is to better understand geologic controls on outer wedge strength and segmentation at spatial scales equivalent to rupture lengths of large earthquakes (≥M 6.7), and to examine potential linkages with shallow megathrust behavior. We use cross-margin profiles, spaced 25 km apart, to characterize along-strike variation in outer wedge width, steepness, and structural vergence (measured between the toe and the outer arc high). The width of the outer wedge varies between 17 and 93 km, and the steepness ranges from 0.9° to 6.5°. Hierarchical cluster analysis of outer wedge width and steepness reveals four distinct regions that also display unique patterns of structural vergence and shape of the wedge: Vancouver Island, British Columbia, Canada (average width, linear wedge, seaward and mixed vergence); Washington, USA (higher width, concave wedge, landward and mixed vergence); northern and central Oregon, USA (average width, linear and convex wedge, mixed and seaward vergence); and southern Oregon and northern California, USA (lower width, convex wedge, seaward and mixed vergence). Variability in outer wedge morphology and structure is broadly associated with along-strike megathrust segmentation inferred from differences in oceanic asthenospheric velocities, patterns of episodic tremor and slow slip, GPS models of plate locking, and the distribution of seismicity near the plate interface. In more detail, our results appear to delineate the extent, geometry, and lithology of dynamic and static backstops along the margin. Varying backstop configurations along the Cascadia margin are interpreted to represent material-strength contrasts within the wedge that appear to regulate the along- and across-strike taper and structural vergence in the outer wedge. We argue that the morphotectonic variability in the outer wedge may reflect spatial variations in shallow megathrust behavior occurring over roughly the last few million years. Comparing outer wedge taper along the Cascadia margin to a global compilation suggests that observations in the global catalog are not accurately representing the range of heterogeneity within individual margins and highlights the need for detailed margin-wide morphotectonic analyses of subduction zones worldwide.

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Journal articles on the topic 'Geology – British Columbia – Gambier Island'

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