GEOSCAN Search Results: Fastlink

GEOSCAN Menu


TitleThe Skipjack Island fault zone - an active transcurrent structure within the upper plate of the Cascadia Subduction Complex
AuthorGreene, H G; Barrie, V; Todd, B J
SourceGeological Society of America, Abstracts With Programs vol. 49, no. 6, 241-5, 2017 p. 1, https://doi.org/10.1130/abs/2017AM-297426
Year2017
Alt SeriesNatural Resources Canada, Contribution Series 20170293
PublisherGeological Society of America
MeetingGeological Society of America Annual Meeting 2017; Seattle, WA; US; October 22-25, 2017
DocumentWeb site
Lang.English
Mediaon-line; digital
File formathtml; pdf
ProvinceBritish Columbia; Western offshore region
NTS92B; 92G/01; 92G/02; 92G/03; 92G/04; 92G/05; 92G/06; 92G/07; 92G/08
AreaVancouver Island; Victoria; Vancouver; Fraser River Delta; Washington State; San Juan Archipelago; Orcas Island; Bellingham; Canada; United States
Lat/Long WENS-124.0000 -122.0000 49.5000 48.0000
Subjectsmarine geology; tectonics; structural geology; surficial geology/geomorphology; geophysics; plate margins; plate motions; bedrock geology; structural features; faults, transcurrent; faults, thrust; fold structures; structural analyses; tectonic evolution; deformation; marine sediments; displacement; geophysical surveys; seismic surveys, marine; seismic reflection surveys; seismic profiles; Cascadia Subduction Zone; Skipjack Island Fault Zone; Devil's Mountain Fault Zone; Cascadia Forearc; Sierra Nevada Terrane; Phanerozoic; Cenozoic; Quaternary
ProgramMarine Geohazards, Public Safety Geoscience
Released2017 10 01
AbstractThe Skipjack Island fault zone has been mapped in the San Juan Islands between Vancouver Island, Canada, and the Washington State mainland, USA. A decade ago, interpretation of multibeam sonar seafloor imagery revealed that Skipjack Island, an east-west striking sedimentary bedrock outcrop, was a fault-controlled structural feature. A major fault separates Skipjack Island from a deformed sedimentary bedrock outcrop on the seafloor to the north. Recently the Skipjack Island fault zone's morphology and extent has been explored both to the west and east of the island using seismic reflection profiling and sediment coring. The character of the Skipjack Island fault zone is well defined locally by the interpreted seismic profiles, which show active faults that displace sediments deposited since the Last Glacial Maximum. The central part of the fault zone, near Skipjack Island, appears as a near-vertical structure that has been subjected to left-lateral motion as evidenced by a bedrock exposure on the seabed north of the island where folded strata bend eastward against the fault, the result of drag from fault motion. Interpretation of recent geophysical data suggests an extension of the Skipjack Island fault zone further to the east where it either cuts through or transitions into a thrust fault and fold belt. The Skipjack Island fault zone is interpreted to be the northern boundary of the San Juan Archipelago with the Devil's Mountain fault zone being the southern boundary. Both of these fault zones represent the longest continuous faults of the San Juan Archipelago, are generally oriented east-west, and are actively deforming the seafloor and producing a clockwise rotation of the major islands within the Archipelago. The Skipjack Island fault zone may represent the northern boundary of the Cascadia forearc where the northward propagating Sierra Nevada tectonostratigraphic terrane is impinging upon stable North America.
Summary(Plain Language Summary, not published)
The Skipjack Island fault zone was mapped in the San Juan Islands between Vancouver Island, Canada, and the Washington State mainland, USA. The fault zone¿s morphology and extent has been explored using geophysical and geological tools. The character of the Skipjack Island fault zone is indicated by active faults that displace sediments deposited since the last glacial period. The Skipjack Island fault zone is interpreted to be the northern boundary of the San Juan Archipelago with the Devil¿s Mountain fault zone being the southern boundary. Both of these fault zones represent the longest continuous faults of the San Juan Archipelago, are generally oriented east¿west, and are actively deforming the seafloor and producing a clockwise rotation of the major islands within the Archipelago.
GEOSCAN ID306309