Tectonics and mineralization of the Kechika Trough, Gataga area, northeastern British Columbia

McClay, Ken; Insley, Martin; Way, N A; Anderton, R.

doi:10.4095/122675

Cited by 3 publications

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“…The lower contact of the proposed Mount Roosevelt Formation is apparently locally conformable with underlying late Early Cambrian, fine-grained quartzarenites in the upper clastic unit of the informal Gataga group (McClay et al 1987(McClay et al , 1988. Where the underlying quartzarenite package is absent, the lower contact is characterized by an angular unconformity on underlying Mesoproterozoic strata (Bell 1968;Taylor et al 1979;Fritz 1979).…”

Section: Revised Stratigraphymentioning

confidence: 94%

“…Basinward and southward, conglomerates correlative with the middle member at Muncho Lake and Moose Lake pass into Middle Cambrian siltstone, minor limestone, and quartzarenite. This may reflect turbidite deposition in deeper water parts of the basin between linear shallow-water carbonate belts, deposited on top of rotated horsts (Mansy 1976;Fritz 1979Fritz , 1980aTaylor et al 1979;McClay et al 1987McClay et al , 1988McClay et al , 1989Fritz et al 1991;Ferri et al 1999).…”

Section: Middle Membermentioning

confidence: 94%

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The Middle Cambrian Mount Roosevelt Formation (new) of northeastern British Columbia: evidence for rifting and development of the Kechika Graben System

Post

Long

2008

Can. J. Earth Sci.

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The eastern margin of the Kechika Graben in the vicinity of Muncho and Moose lakes, northeastern British Columbia, contains Middle Cambrian rift-related strata herein named the Mount Roosevelt Formation. The formation conformably overlies a quartzite package equivalent to the uppermost clastic unit of the informal late Early Cambrian Gataga group (Bonnia-Olenellus zone) and is conformably overlain by a thick, unnamed carbonate sequence of Middle Cambrian age (Plagiura-Poliella zone). The Mount Roosevelt Formation is subdivided into three members. The lowermost member is characterized by oöid-bearing siltstone and sandstone, interbedded with dolostone, limestone, and hematitic conglomerate. Conformably above this, the middle member is a thick sequence of polymict cobbly pebble conglomerate. The upper member includes karstified dolostone, calcareous-cemented conglomerate and sandstone, and limestone. Collectively the Mount Roosevelt Formation reflects alluvial fan delta progradation into a transgressive marine environment. Deposition occurred in an active fault-controlled basin, located on the eastern margin of the Kechika Graben adjacent to the Muskwa High. Basin initiation in the late Early Cambrian coincided with the reactivation of pre-existing regional faults. High rates of subsidence during the initial phase of extension were accommodated on these faults, which provided a locus for fan delta deposition. Continuing high rates of subsidence limited basinward fan delta development. Deposition of the formation ended with base-level transgression in the early Middle Cambrian that drowned the fan deltas and the adjacent Muskwa High and allowed development of the Kechika Trough above the older graben system. Résumé :Située à proximité des lacs Muncho et Moose dans le nord-est de la Colombie-Britannique, la bordure est du graben de Kechika contient des strates, ici nommées la Formation de Mount Roosevelt (Cambrien moyen), qui sont reliées à la distension. La formation repose en concordance sur un ensemble de quartzite équivalent à l'unité supérieure, clastique, du groupe de Gataga, informel, datant du Cambrien précoce (zone à Bonnia-Olenellus); elle est recouverte en concordance par une épaisse séquence de carbonate, sans nom, datant du Cambrien moyen (zone à Plagiura-Poliella). La Formation de Mount Roosevelt est subdivisée en trois membres. Le membre inférieur est caractérisé par des siltstones et des grès à oolites, interstratifiés avec des dolomies, des calcaires, et des conglomérats hématitiques. Par-dessus, en concordance, le membre du centre est composé d'une épaisse séquence de conglomérat grenu, hétérogène et caillouteux. Le membre supérieur comprend de la dolomie karstifiée, du conglomérat et du grès à ciment calcaire, et du calcaire. Dans son ensemble, la Formation de Mount Roosevelt est le reflet de la progradation d'un delta alluvionnaire en un environnement marin de transgression. La déposition a eu lieu dans un bassin contrôlé par des failles actives situé sur la bordure est du graben de Kechika, voisi...

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Section: Revised Stratigraphymentioning

confidence: 94%

Section: Middle Membermentioning

confidence: 94%

The Middle Cambrian Mount Roosevelt Formation (new) of northeastern British Columbia: evidence for rifting and development of the Kechika Graben System

Post

Long

2008

Can. J. Earth Sci.

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Inversion of the Kechika Trough, Northeastern British Columbia, Canada

McClay

Insley

Anderton

1989

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Summary The Kechika Trough, in the western Rocky Mountains of northern Canada, is a NW-trending fold and thrust belt of Hadrynian through Mississippian strata within the telescoped passive margin of ancestral North America. The Kechika Trough underwent major crustal extension in the Mid-Late Devonian with the deposition of coarse to fine ‘Antler’ type black clastics in an asymmetrical basin consisting of a terraced half-graben system to the west and a roll-over structure to the east. Inversion and contraction of the Kechika Trough occurred during the Jurassic-Cretaceous Columbian-Laramide orogeny. The geometries of the resultant fold and thrust systems were strongly controlled by the half-graben extensional architectures and by the geometries of the synrift sediment packages. Inversion structures include contractionally reactivated extensional faults, rotated and re-utilized extensional faults, and thrust faults pinned by extensional faults as a result of buttressing against rigid sediment wedges. Inversion of the synrift sediments is associated with strongly developed chevron folding, pervasive cleavage development and imbrication by out-of-half-graben thrust faults. These thrust faults may locally climb down stratigraphic section in the direction of transport as a result of cutting through strata tilted by Mid-Late Devonian extensional faults. Major stratigraphic contrasts between adjacent thrust packages have been resolved in terms of lateral facies differences produced by extension, rather than by over-complex thrust geometries. Although syndepositional extensional faults are not preserved in the thrust belt, their position and geometry may be inferred from an analysis of structural, stratigraphic and sedimentological relationships.

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Upper Cambrian to Lower Silurian stratigraphic framework of platform-to-basin fades, northeastern British Columbia

Pyle

Barnes

2000

Bulletin of Canadian Petroleum Geology

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Tectonics and mineralization of the Kechika Trough, Gataga area, northeastern British Columbia

Cited by 3 publications

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The Middle Cambrian Mount Roosevelt Formation (new) of northeastern British Columbia: evidence for rifting and development of the Kechika Graben System

The Middle Cambrian Mount Roosevelt Formation (new) of northeastern British Columbia: evidence for rifting and development of the Kechika Graben System

Inversion of the Kechika Trough, Northeastern British Columbia, Canada

Upper Cambrian to Lower Silurian stratigraphic framework of platform-to-basin fades, northeastern British Columbia

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