Petroleum, mineral, and other resource potential in the offshore Pacific, British Columbia, Canada

Ferguson, R; King, H M; Kublik, Kristina; Rohr, Kristin M. M.; Kung, L E; Lister, C J; Fustic, Milovan; Hayward, N; Brent, T A; Jassim, Y

doi:10.4095/308395

Cited by 3 publications

(6 citation statements)

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“…sediments would create hydrate reflectors throughout the region but this is not observed (Ferguson et al, 2018;Han et al, 2016;Hyndman et al, 1994). Faults from bending stresses alone tend to deform the lower sediment section and are not associated with bright spots or hydrate reflectors.…”

Section: 1029/2018gc007851mentioning

confidence: 96%

“…The link between bright spots and fault systems (Figure ) leads us to infer that methane has been advected toward the surface through the fault systems. Widespread biogenic processes utilizing organic carbon in the sediments would create hydrate reflectors throughout the region but this is not observed (Ferguson et al, ; Han et al, ; Hyndman et al, ). Faults from bending stresses alone tend to deform the lower sediment section and are not associated with bright spots or hydrate reflectors.…”

Section: Initiation Of Strike‐slip Faulting and Serpentinizationmentioning

confidence: 99%

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Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary

Rohr

Furlong

Riedel

2018

Geochem Geophys Geosyst

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The Nootka fault zone is a ridge‐trench‐trench transform fault that was initiated ~4 Ma when the Explorer ridge became independent of the Juan de Fuca ridge. Multibeam data around the fault zone and a compilation of several seismic reflection surveys provide insight into initiation of strike‐slip faults. Previous interpretations assumed that the two faults seen cutting the seafloor are subparallel to shear between the Explorer and Juan de Fuca plates and formed instantaneously at 4 Ma. Increased data density shows that these faults are subparallel to seafloor magnetic anomalies and appear to have utilized extensional faults formed at the ridge. They are surrounded by numerous buried steeply dipping, small‐offset growth faults; at least some of which are likely still active. Our observations corroborate analogue models of strike‐slip fault initiation that predict formation of Riedel‐like shears within a zone of faulting and that displacement localizes over time. The existence of several long subparallel faults and a very wide zone of faulting has been predicted by models of distributed shear at depth. Along the Nootka fault zone basement has risen by several hundred meters and bright reversed‐polarity reflectors some of which are interpreted to be methane hydrate reflectors are common. Hydration, likely as serpentinization, of the upper mantle could explain both sets of observations: Serpentinization can result in a 30–50% volume expansion and methane is observed in vents driven by this process. Biogenic sources of methane are likely to be present and concentrated by currently active fluid flow in the faulted sediments.

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Section: 1029/2018gc007851mentioning

confidence: 96%

Section: Initiation Of Strike‐slip Faulting and Serpentinizationmentioning

confidence: 99%

Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary

Rohr

Furlong

Riedel

2018

Geochem Geophys Geosyst

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“…Cooling is in effect across the entire plate, a variable sedimentary load affects the plate up to 150 km from the trench, and subduction loading affects crust within 50 to 70 km of the trench (Han et al, 2016). Sedimentary thickness varies from centimetres on very young basalt up to 3 km in some parts of the trench (Han et al, 2017;Ferguson et al, 2018).…”

Section: Regional Geologymentioning

confidence: 99%

“…Single and multichannel seismic reflection data interpreted here range in age from 1985 (Davis et al, 1992) to 2012 (Han et al, 2016). These data were compiled during a regional review of geology to assess setting aside areas as marine conservation zones (Ferguson et al, 2018). Data collected in 1995 and 1996 were published by Rosenberger et al (2000), lines 85-01 and 85-02 by Davis and Hyndman (1989), lines 85-07 and 85-09 by Hasselgren and Clowes (1995), and MGL1112-02 was published by Han et al (2016).…”

Section: Datamentioning

confidence: 99%

From mid-plate to subduction zone: stratigraphy of the northeast Juan de Fuca Plate, offshore British Columbia

Rohr

King

Riedel

et al. 2019

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“…Although the architecture of fold and thrust belts, their décollements, and their associated magmatism are commonly investigated along a suite of geological and/or geophysical cross sections parallel to the direction of shortening (e.g., Pfiffner, ), their 3D geometry and structural relationships are commonly less well understood. Herein, a new geophysical approach, involving the 3D inversion of gravity data, defines the distribution and depth extent of bodies with either low (i.e., granitic intrusions or sedimentary rocks; e.g., Ferguson et al, ) or high (i.e., mafic or ultramafic intrusions) density contrasts. In the northern Cordillera of Canada and Alaska, the technique is applied to model the distribution and depth extent of low‐density sources, including granitic rocks that represent a volumetrically large component of the northern Cordilleran crust (e.g., Hart et al, ).…”

Section: Introductionmentioning

confidence: 99%

The 3D Geophysical Investigation of a Middle Cretaceous to Paleocene Regional Décollement in the Cordillera of Northern Canada and Alaska

Hayward

2019

Tectonics

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A new approach to the 3D inversion and interpretation of gravity data is applied to the crustal architecture of the northern Cordillera of Canada and Alaska. The technique models the distribution and depth extent of rocks with systematic density contrasts, such as sedimentary or intrusive rocks. In the northern Cordillera, the geometry of low-density zones, primarily associated with middle to Late Cretaceous granitic intrusions, and Neoproterozoic and Cretaceous sedimentary rocks, is defined. Variation in the depth extent of these zones delimits a surface, interpreted herein as a regional décollement syntectonic with, or postdating, middle Cretaceous intrusions, but predating and displaced~430 km by the Eocene-aged Tintina fault. The décollement trends N35°E and shallows from a depth of~15-20 km beneath Selwyn basin tõ 11 km beneath the Mackenzie Mountains. Here surface faults echo the décollement geometry, linked to fold and thrust belt development between the middle Cretaceous and Paleocene. The décollement continues southward for an unknown distance into northern British Columbia, but the Liard line represents a structural discontinuity between the fold and thrust belts of the Mackenzie Mountains and northern Rocky Mountains. The décollement's northwestern extent is broadly defined by surface faults in the northern Ogilvie Mountains. However, prior to Tintina fault displacement, the décollement was likely connected to a fold and thrust belt and related décollement in east-central Alaska. Estimates of post-middle Cretaceous exhumation suggest regional tectonic modification of the décollement, possibly including the presently active detachment inferred for the weak lower crust.HAYWARD 307

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Petroleum, mineral, and other resource potential in the offshore Pacific, British Columbia, Canada

Cited by 3 publications

References 0 publications

Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary

Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary

From mid-plate to subduction zone: stratigraphy of the northeast Juan de Fuca Plate, offshore British Columbia

The 3D Geophysical Investigation of a Middle Cretaceous to Paleocene Regional Décollement in the Cordillera of Northern Canada and Alaska

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