Stratal composition and stratigraphic organization of stratal elements in an ancient deep‐marine basin‐floor succession, Neoproterozoic Windermere Supergroup, British Columbia, Canada

Sedimentology ◽  
2015 ◽  
Vol 63 (1) ◽  
pp. 136-175 ◽  
Author(s):  
Viktor Terlaky ◽  
Jonathan Rocheleau ◽  
Robert William Charles Arnott
Keyword(s):  
British Columbia ◽  
Windermere Supergroup ◽  
Basin Floor ◽  
Marine Basin

The origin and significance of convolute lamination and pseudonodules in an ancient deep-marine turbidite system: From deposition to diagenesis

2020 ◽  
Vol 90 (5) ◽  
pp. 480-493
Author(s):  
Omar N. Al-Mufti ◽  
R. William C. Arnott
Keyword(s):  
Isotope Composition ◽  
Coarse Grained ◽  
Intergranular Porosity ◽  
Carbonate Cement ◽  
Windermere Supergroup ◽  
Basin Floor ◽  
Turbidite System ◽  
Sediment Deformation ◽  
General Transport ◽  
Marine Basin

ABSTRACT Soft-sediment deformation structures, like convolute lamination and pseudonodules, are common in deep-marine turbidites, but details of their origin and timing of formation remain a source of debate. Deep-marine basin-floor deposits of the Neoproterozoic Upper Kaza Group (Windermere Supergroup) crop out superbly in the Castle Creek study area and provide an ideal laboratory to investigate these aspects in convolute-laminated pseudonodules, and also how that deformation influenced later diagenesis. Pseudonodules consist of well-sorted, matrix-poor, upper medium- to coarse-grained, planar-stratified or cross-stratified sandstone that are underlain and overlain by comparatively more poorly sorted, matrix-rich, graded sandstone of similar grain size. Deposition of the stratified pseudonodules is interpreted to have occurred during the same event that deposited the graded sandstone, albeit during a period of general transport bypass, whereby isolated, shallow, seafloor depressions became filled with well-sorted, stratified sand. As stratified sand accumulated the depressions slowly subsided until a critical thickness had built up and exceeded the load-bearing capacity of the substrate composed of graded sand. This destabilized the surface separating the two layers and resulted in the stratified unit foundering, and in some cases becoming completely enveloped by, the upward-displaced lower-density substrate. Surprisingly, despite the deformed macroscopic character of the stratified sediment, primary grain fabric, including intergranular porosity up to 40%, was preserved and influenced early diagenesis, which, owing to dispersed phosphate cement and depleted carbon isotope composition of the pervasive carbonate cement, would have begun very near the sediment–water interface. Importantly also, pseudonodules are common in basin-floor deposits but comparatively rare in continental-slope strata. Expanding flow conditions over the basin floor would have promoted grain settling, and in turn development of a more stably (density) stratified flow structure. Ultimately this resulted in higher local rates of sedimentation on the basin floor and the accumulation of a substrate more prone to later liquidization.

Ediacaran fossils and dubiofossils, Miette Group of Mount Fitzwilliam area, British Columbia

1991 ◽  
Vol 28 (10) ◽  
pp. 1541-1552 ◽  
Author(s):  
H. J. Hofmann ◽  
E. W. Mountjoy ◽  
M. W. Teitz
Keyword(s):  
British Columbia ◽  
Shallow Water ◽  
Rocky Mountains ◽  
Carbonate Mounds ◽  
Windermere Supergroup

Shallow-water clastic beds flanking stromatolitic carbonate mounds in the upper part of the Vendian Miette Group (Windermere Supergroup) of the Rocky Mountains contain a poorly preserved, soft-bodied fauna that comprises morphologically very variable discoid remains; these include the taxa Beltanella sp., cf. B. grandis, Charniodiscus? sp., Irridinitus? sp., Nimbia occlusa, Protodipleurosoma sp., cf. P. rugulosum, and Zolotytsia? sp. and seven types of dubiofossils.

The initiation of the early Paleozoic Cordilleran miogeocline: evidence from the uppermost Proterozoic – Lower Cambrian Hamill Group of southeastern British Columbia

1988 ◽  
Vol 25 (1) ◽  
pp. 1-19 ◽  
Author(s):  
William J. Devlin ◽  
Gerard C. Bond
Keyword(s):  
British Columbia ◽  
Lower Cambrian ◽  
Direct Evidence ◽  
Thermal Anomaly ◽  
Passive Margin ◽  
Early Paleozoic ◽  
Upper Proterozoic ◽  
Windermere Supergroup ◽  
Depositional Setting ◽  
Thermal Subsidence

The uppermost Proterozoic–Lower Cambrian Hamill Group of southeastern British Columbia contains geologic evidence for a phase of extensional tectonism that led directly to the onset of thermally controlled subsidence in the Cordilleran miogeocline. Moreover, the Hamill Group contains the sedimentological record of the passage of the ancient passive margin from unstable tectonic conditions associated with rifting and (or) the earliest phases of thermal subsidence to post-rift conditions characterized by stabilization of the margin and dissipation of the thermal anomaly generated during the rift phase (the rift to post-rift transition). Widespread uplift that occurred prior to and during the deposition of the lower Hamill Group is indicated by an unconformable relation with the underlying Windermere Supergroup and by stratigraphic relations between Middle and Upper Proterozoic strata and unconformably overlying upper Lower Cambrian quartz arenites (upper Hamill Group) in the southern borderlands of the Hamill basin. In addition, the coarse grain size, the feldspar content, the depositional setting, and the inferred provenance of the lower Hamill Group are all indicative of the activation of basement sources along the margins of the Hamill basin. Geologic relations within the Hamill Group that provide direct evidence for extensional tectonism include the occurrence of thick sequences of mafic metavolcanics and rapid vertical facies changes that are suggestive of syndepositional tectonism.Evidence of extensional tectonism in the Hamill Group directly supports inferences derived from tectonic subsidence analyses that indicate the rift phase that immediately preceded early Paleozoic post-rift cooling could not have occurred more than 10–20 Ma prior to 575 ± 25 Ma. These data, together with recently reported isotopic data that suggest deposition of the Windermere Supergroup began ~730–770 Ma, indicate that the rift-like deposits of the Windermere Supergroup are too old to represent the rifting that led directly to the deposition of the Cambro-Ordovician post-rift strata. Instead, Windermere sedimentation was apparently initiated by an earlier rift event, probably of regional extent, that was part of a protracted, episodic rift history that culminated with continental breakup in the latest Proterozoic – Early Cambrian.

Geochronology and tectonic implications of magmatism and metamorphism, southern Kootenay Arc and neighbouring regions, southeastern British Columbia. Part I: Jurassic to mid-Cretaceous

1983 ◽  
Vol 20 (12) ◽  
pp. 1891-1913 ◽  
Author(s):  
D. A. Archibald ◽  
J. K. Glover ◽  
R. A. Price ◽  
E. Farrar ◽  
D. M. Carmichael
Keyword(s):  
British Columbia ◽  
North America ◽  
Regional Metamorphism ◽  
Granitic Rocks ◽  
Early Paleozoic ◽  
Small Bodies ◽  
Western Margin ◽  
The North ◽  
Windermere Supergroup ◽  
Igneous Activity

K–Ar dates and U–Pb zircon dates define three periods of igneous activity in the southern Kootenay Arc: (1) emplacement of late-synkinematic to post-kinematic granodioritic plutons in mid-Jurassic time (170–165 Ma) accompanying amphibolite-facies regional metamorphism; (2) emplacement of post-kinematic granitic plutons in mid-Cretaceous time (~100 Ma); and (3) emplacement of small bodies of syenite in Eocene time (~50 Ma) in the western part of the area. Micas from mid-Jurassic plutons that yield the oldest K–Ar dates (158–166 Ma) also yield plateau-shaped 40Ar/39Ar age spectra. Age spectra for biotites younger than these but older than 125 Ma reflect thermal overprinting.In southeastern British Columbia, the Kootenay Arc marks the transition from the North American rocks of the Cordilleran miogeocline to the tectonic collage of allochthonous terranes that have been accreted to it.Deformation, metamorphism, and plutonism recorded in rocks of the southern Kootenay Arc commenced in mid-Jurassic time as a composite allochthonous terrane was accreted to and overlapped the western margin of North America. The geochronology and metamorphic geothermobarometry show that in less than 10 Ma between 166 and 156 Ma: (1) rocks as young as the late Proterozoic Windermere Supergroup and the early Paleozoic Lardeau Group were carried rapidly to depths of 20–24 km while being deformed and intruded by granitic rocks of a hornblende–biotite suite that were also being emplaced at a much shallower level in the overriding allochthonous terrane; and (2) the miogeoclinal rocks of the Windermere Supergroup in the southern Kootenay Arc were then uplifted by more than 7 km at an estimated rate of 2 mm/year, and thrust over the allochthonous terrane prior to being intruded by post-kinematic granitic rocks, many of which belong to the two-mica suite of mid-Cretaceous age..

Superimposed low-grade metamorphism in the Mount Fisher area, southeastern British Columbia—implications for the East Kootenay orogeny

1982 ◽  
Vol 19 (3) ◽  
pp. 476-489 ◽  
Author(s):  
M. E. McMechan ◽  
R. A. Price
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Rocky Mountains ◽  
Regional Metamorphism ◽  
Low Grade ◽  
Canadian Cordillera ◽  
Windermere Supergroup ◽  
Granitic Intrusion ◽  
Block Faulting ◽  
Middle Proterozoic

Middle Proterozoic (~1500–1350 Ma) Belt–Purcell strata exposed in the Purcell and southwestern Rocky Mountains were affected by at least three distinct episodes of deformation and regional metamorphism. The oldest episode (1300–1350 Ma) apparently terminated Belt–Purcell sedimentation and involved folding, regional metamorphism, and granitic intrusion. The second episode (800–900 Ma) occurred during deposition of the Windermere Supergroup and involved uplift, block faulting, and low-grade regional metamorphism. Mesozoic–Cenozoic metamorphism, deformation, and plutonism overprinted the results of the earlier deformation and metamorphism.Illite crystallinity and muscovite polymorph ratios indicate that Purcell strata in the Mount Fisher area are in the lower green-schist to prehnite–pumpellyite facies of regional metamorphism. In the Steeples and Fisher blocks this metamorphism is related to structures that formed during the Late Cretaceous – Paleocene deformation. However, in the Sand Creek block the regional metamorphism is related to the development of a spaced cleavage that is folded by a Late Cretaceous – Paleocene nappe. Regional considerations suggest that this cleavage formed during the 1300–1350 Ma episode of deformation and metamorphism.The "East Kootenay orogeny" as currently defined embraces the two older episodes of tectonism. It is proposed that the term East Kootenay orogeny be restricted to designate the 1300–1350 Ma episode and that the term "Goat River orogeny" designate the 800–900 Ma episode of tectonism. The East Kootenay and Goat River orogenies appear to be correlative with the Racklan and Hayhook orogenies recognized in the northern Canadian Cordillera.

scholarly journals Zircon and Monazite Age of a Granitic Clast in Toby Conglomerate [Windermere Supergroup], Canal Flats, British Columbia

1981 ◽  
Author(s):  
W D Loveridge ◽  
G B Leech ◽  
R D Stevens ◽  
R W Sullivan
Keyword(s):  
British Columbia ◽  
Windermere Supergroup
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