Geological Investigations in Calder River map area, Central Wopmay Orogen, District of Mackenzie

Hildebrand, Robert S.; Bowring, Samuel A.; Andrew, K P E; Gibbins, Samantha; Squires, GC

doi:10.4095/122550

Cited by 6 publications

(8 citation statements)

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“…2D). Throughout most of the zone, the folds trend northwest but as the axial traces approach the eastern margin of the zone, they bend progressively N-S, parallel to the edge of the Slave craton (Hildebrand et al, 1987b(Hildebrand et al, , 1990Hildebrand and Bowring, 1988). The folds plunge gently everywhere.…”

Section: Great Bear Magmatic Zonementioning

confidence: 95%

The nature of volcano-plutonic relations and the shapes of epizonal plutons of continental arcs as revealed in the Great Bear magmatic zone, northwestern Canada

et al. 2010

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The shapes of plutons and their emplacement mechanisms, the connection between the volcanic and plutonic realms, and the development of batholiths have been of interest to geologists since they realized that plutons were once low viscosity magma. These issues have proven diffi cult to resolve because there are few places that have enough relief to expose the critical relations. The Great Bear magmatic zone, a Paleoproterozoic continental arc located in northern Canada's Wopmay orogen, provides an informative fi eld setting to resolve some of these issues because the rocks are generally non-metamorphosed and were broadly folded such that calderas, stratovolcanoes, and a wide variety of plutons are exposed in oblique cross-section on fold limbs in an area of subdued topographic relief.Early mafi c plutons intruded co-magmatic pillow basalt piles as thin sheets with aspect ratios of 10-15. Plutons of intermediate composition, temporally associated with andesitic stratocones, have fl at or slightly domical roofs and fl at fl oors, and aspect ratios in the range of 5-10. Granodioritic to monzodioritic plutons that cut thick sequences of ashfl ow tuff and related volcaniclastic rocks are generally sheet-like bodies with aspect ratios of 10-20, except where they intrude calderas and form resurgent plutons. Granitic plutons intrude at slightly deeper crustal levels, are generally younger, and typically have miarolytic cavities, pegmatites, and associated dike swarms. The granites have fl at roofs and fl oors but generally have lower aspect ratios than the intermediate composition plutons.Cycles-where magma bodies were fi rst partially evacuated by eruption, then were re-energized and rose into their own ejecta to form plutons-span the compositional range from basalt to rhyodacite. The cycle of eruption, with the partial evacuation of chambers and subsequent rise of remaining magma to even higher levels in the crust explains why it is generally so diffi cult to link volcanic eruptions to specifi c plutons.The overall development of the Great Bear magmatic zone-from small-scale local eruptions of basalt to voluminous eruptions of intermediate composition ash-fl ow tuff followed by wide-scale emplacement of granitic plutons-is interpreted to represent input of subduction-related magmas, which led to progressive heating, melting, and wholesale upward differentiation of the crust beneath the arc.

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Section: Great Bear Magmatic Zonementioning

confidence: 95%

The nature of volcano-plutonic relations and the shapes of epizonal plutons of continental arcs as revealed in the Great Bear magmatic zone, northwestern Canada

et al. 2010

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“…See text for further discussion. Easton 1980Easton , 1981aEaston ,1981bHildebrand 1981Hildebrand , 1985Hildebrand et al 1983Hildebrand et al , 1987aHildebrand et al , 1987bHildebrand et al , 2010aHildebrand et al , 2010bSt-Onge et al 1983, 1991Bowring 1984;Reichenbach 1991;Gandhi 1994;Goad et al 2000;Gandhi et al 2001;Gandhi and van Breemen 2005;Rivers 2006a, 2006b;Jackson 2008;Shakotko et al 2012;Jackson and Ootes 2012;Jackson et al 2013). Figure 7 illustrates a minimum 80 million year magmatic evolution from ca.…”

Section: Stratigraphy and Petrological Evolutionmentioning

confidence: 99%

“…1, 2;Fraser et al 1972;Badham 1973;Hoffman 1973Hoffman , 1980Hoffman , 1984Hoffman , 1988aHoffman and McGlynn 1977;Hoffman et al 1976;King 1986, 1987;Villeneuve et al 1991Villeneuve et al , 1993Aspler et al 2003;Cook and Erdmer 2005;Jackson 2008;Hildebrand et al 1987aHildebrand et al , 1987bHildebrand et al , 2010aHildebrand et al , 2010bJackson and Ootes 2012;Jackson et al 2013;Ootes et al 2013). The Coronation margin includes Archean crust, the ca.…”

Section: Geological Settingmentioning

confidence: 99%

“…Screens of volcanic rocks that range from andesite to trachyandesite to rhyolite are preserved in a sea of younger plutons that only rarely contain penetrative deformation fabrics. These plutonic rocks range in composition from gabbro to syenogranite, although they are predominantly monzonitic to monzogranitic (e.g., Fraser et al 1972;Badham 1973;Hildebrand et al 1987bHildebrand et al , 2010bGandhi 1994;Gandhi et al 2001;Ootes et al 2013).…”

Section: Geological Settingmentioning

confidence: 99%

“…Along the north-striking Wopmay fault zone, mixed basalt, rhyolite, and red arkosic rocks have been assigned to the Dumas Group (Hoffman 1978;Easton 1981b;Hildebrand et al 1987b;Jackson and Ootes 2012) and are considered the eastern equivalent of the LaBine Group (Hildebrand et al 1987b). Near Ham Lake (HL in Fig.…”

Section: Rhyodacite Flow (Hl)mentioning

confidence: 99%

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Chronostratigraphy of the Hottah terrane and Great Bear magmatic zone of Wopmay Orogen, Canada, and exploration of a terrane translation model

et al. 2015

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Abstract:The Paleoproterozoic Hottah terrane is the westernmost exposed bedrock of the Canadian Shield and a critical component for understanding the evolution of the Wopmay Orogen. Thirteen new high-precision U-Pb zircon crystallization ages are presented and support field observations of a volcano-plutonic continuum from Hottah terrane through to the end of the Great Bear magmatism, from >1950 to 1850 Ma. The new crystallization ages, new geochemical data, and newly published detrital zircon U-Pb data are used to challenge hitherto accepted models for the evolution of the Hottah terrane as an exotic arc and microcontinent that arrived over a west-dipping subduction zone and collided with the Slave craton at ca. 1.88 Ga. Although the Hottah terrane does have a tectonic history that is distinct from that of the neighbouring Slave craton, it shares a temporal history with a number of domains to the south and east -domains that were tied to the Slave craton by ca. 1.97 Ga. It is interpreted herein that Hottah terrane began to the south of its current position and evolved in an active margin over an always east-dipping subduction system that began prior to ca. 2.0 Ga and continued to ca. 1.85 Ga, and underwent tectonic switching and migration. The stratigraphy of the ca. 1913-1900 Ma Hottah plutonic complex and Bell Island Bay Group includes a subaerial rifting arc sequence, followed by basinal opening represented by marginal marine quartz arenite and overlying ca. 1893 Ma pillowed basalt flows and lesser rhyodacites. We interpret this stratigraphy to record Hottah terrane rifting off its parental arc crust -in essence the birth of the new Hottah terrane. This model is similar to rapidly rifting arcs in active margins -for example, modern Baja California. These rifts generally occur at the transition between subduction zones (e.g., Cocos-Rivera plates) and transtensional shear zones (e.g., San Andreas fault), and we suggest that extension-driven transtensional shearing, or, more simply, terrane translation, was responsible for the evolution of Bell Island Bay Group stratigraphy and that it transported this newly born Hottah terrane laterally (northward in modern coordinates), arriving adjacent to the Slave craton at ca. 1.88 Ga. Renewed east-dipping subduction led to the Great Bear arc flare-up at ca. 1876 Ma, continuing to ca. 1869 Ma. This was followed by voluminous Great Bear plutonism until ca. 1855 Ma. The model implies that it was the westerly Nahanni terrane and its subducting oceanic crust that collided with this active margin, shutting down the >120 million year old, east-dipping subduction system.

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Fault reconstructions using aeromagnetic data in the Great Bear magmatic zone, Northwest Territories, Canada

Hayward

Corriveau

2014

Can. J. Earth Sci.

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The Great Bear magmatic zone, located in Wopmay orogen, is a 1.875–1.84 Ga belt, 450 km long by 100 km wide of volcanic and allied plutonic rocks interpreted as a Paleoproterozoic magmatic arc. The belt, which contains economically important mineralization, was folded and subsequently cut by a swarm of northeast-striking transcurrent faults, which are part of a regional conjugate fault system interpreted to result from terminal collision of the Nahanni – Fort Simpson terrane. Fault reconstructions based on the interpretation of aeromagnetic data and geological maps provide first-order models of deformation mechanisms associated with, and the configuration of the Great Bear magmatic zone prior to, its dissection by northeast-striking transcurrent faults. The models show that vertical axis block rotation (plane strain) of ∼4.5° can explain fault offsets in the south, but that greater rotation is required to explain many of the displacements in the north. However, offsets on transcurrent faults that border the Camsell River district are greater than can be explained by vertical axis block rotation model alone and may include a component of Mesoproterozoic contractional deformation associated with the Racklan–Forward orogeny. Following reconstruction, iron oxide alkali alteration and associated mineralization, which pre-date transcurrent faulting, form a pair of northerly trending zones on the east and west margins of the belt. We suggest that these zones, whose exposure is related to broad synclinal folding of some of the oldest rocks in the Great Bear magmatic zone, are where iron oxide copper–gold (IOCG)-targeted exploration efforts should be focused on these areas in both outcrop and subcrop.

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Geological Investigations in Calder River map area, Central Wopmay Orogen, District of Mackenzie

Cited by 6 publications

References 0 publications

The nature of volcano-plutonic relations and the shapes of epizonal plutons of continental arcs as revealed in the Great Bear magmatic zone, northwestern Canada

The nature of volcano-plutonic relations and the shapes of epizonal plutons of continental arcs as revealed in the Great Bear magmatic zone, northwestern Canada

Chronostratigraphy of the Hottah terrane and Great Bear magmatic zone of Wopmay Orogen, Canada, and exploration of a terrane translation model

Fault reconstructions using aeromagnetic data in the Great Bear magmatic zone, Northwest Territories, Canada

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