Lithospheric geometry of the Wopmay orogen from a Slave craton to Bear Province magnetotelluric transect

Spratt, J.; Jones, Alan G.; Jackson, Valerie A.; Collins, Louise; Avdeeva, Anna

doi:10.1029/2007jb005326

Cited by 61 publications

(43 citation statements)

References 102 publications

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“…These include deep-seismic reflection profiling (Cook et al, 1999;Cook and Erdmer, 2005;Oueity and Clowes, 2010), magnetotelluric experiments (Wu et al, 2005;Spratt et al, 2009), and teleseismic data acquisition (Bostock, 1998;Mercier et al, 2008;Snyder et al, 2014). The 2D geophysical data in those studies collectively support that there is a stacked east-dipping lithospheric mantle beneath this region, related to subducted and frozen oceanic crust (e.g., Cook et al, 1999).…”

Section: Geophysicsmentioning

confidence: 95%

A Paleoproterozoic Andean-type iron oxide copper-gold environment, the Great Bear magmatic zone, Northwest Canada

Ootes

Snyder

Davis

et al. 2017

Ore Geology Reviews

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Iron oxide copper-gold (IOCG) and associated iron-oxide apatite (IOA) styles of metallic mineralization are recognized throughout the Paleoproterozoic Great Bear magmatic zone of the northwest Canadian Shield. The Great Bear magmatic zone was constructed between ca. 1876 and 1855 Ma on top of the older Hottah terrane, which preserves continental arc magmatism that began around ca. 2.0 to 1.97 Ga and continued between ca. 1.93 and 1.89 Ga. The Great Bear represents the final stages of ca. 150 million years of intermittent and pulsed magmatism related to an evolving continental orogenic belt. The preserved geology supports a dramatic geodynamic change in the subduction zone process at ca. 1875 Ma, a key driving mechanism for magma and metal mobilization, and was rapidly followed by a large-scale introduction of felsic-intermediate plutons. The overall tectonic setting is partially constrained from new and previously published geochemical data that show that the volcanic and plutonic rocks are high-K calc-alkaline to shoshonitic in nature (e.g., high K 2 O, Th/Yb, and Ce/P 2 0 5 ). They also have suprasubduction-zone geochemical signatures, including primitive mantle normalized positive Th and negative Nb, P, and Ti anomalies. The data support the primary melts were derived from a GLOSS-modified mantle wedge. Three-dimensional rendering of geophysical datasets suggest that two (of four) preserved surfaces within the upper mantle lithosphere, at 70 to 120 km depths, represent frozen, subducted oceanic slabs, and likely were the drivers for the bulk of Hottah and Great Bear arc magmatism. The older slab is northwest-striking and dips 12⁰ to 15⁰ northeast, whereas the younger is deeper and north-striking, dipping 13⁰ east. The geometry of the surfaces are comparable with 4D modeling, where a subduction zone is temporarily shut down due to plateau collision, and then steps oceanward and re-initiates; there is no need for polarity reversal of the subduction system. This new geometry and the related inferences about process should be the focus of future research in the region, but for the time-being it can be stated that these subduction and collisional processes were the first order control on lithospheric evolution, and therefore metallic mineralization. Overall, the Great Bear magmatic zone IOCG and related mineralization is not comparable to other Proterozoic IOCG belts, such as those in Australia. However, the complexity of mineralization styles, the spatial-temporal relationship between IOA and IOCG mineralization, the suprasubduction zone environment, and a major change in tectonic regime are features similar to Andean-type IOCG mineralization, as well as Cordilleran alkali porphyry Cu-A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT3 Au deposits. This further establishes the linkages between subduction zone processes and IOCG formation, as well as relationships in the IOCG-porphyry deposit continuum model.

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Section: Geophysicsmentioning

confidence: 95%

A Paleoproterozoic Andean-type iron oxide copper-gold environment, the Great Bear magmatic zone, Northwest Canada

Ootes

Snyder

Davis

et al. 2017

Ore Geology Reviews

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“…Geophysical studies have shown that the Hottah terrane and Great Bear magmatic zone have properties distinct from those of the Slave craton and overlying Coronation margin to the east, and the Fort Simpson magnetic high and enigmatic Nahanni terrane to the west ( Fig. 1; Fraser et al 1972;Hoffman 1988a;Cook et al 1999;Aspler et al 2003;Cook and Erdmer 2005;Wu et al 2005;Spratt et al 2009;Oueity and Clowes 2010;Ootes et al 2013;Hayward and Corriveau 2014). Much of what has been "imaged" in these experiments is covered by the Phanerozoic platform, and directly assessing the underlying bedrock components, especially of the Hottah terrane, is not currently possible.…”

Section: Geological Settingmentioning

confidence: 99%

“…The Wopmay fault zone is a north-south-striking crustal-scale fault that delimits the western extent of exposed Archean rocks in the Wopmay Orogen (Figs. 1, 2;St-Onge et al 1983;King 1986;Bowring and Podosek 1989;Housh et al 1989;Jackson 2008;Jackson et al 2006Jackson et al , 2013Spratt et al 2009;Jackson and Ootes 2012: also called medial zone by Hildebrand et al 1991Hildebrand et al , 2010a. West of Wopmay fault zone are the remnants of the >1.9 Ga Hottah terrane, which was extensively overprinted by ca.…”

Section: Geological Settingmentioning

confidence: 99%

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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“…Variations in the lithospheric mantle may hold clues to metal enrichment in overlying geological provinces (Spratt et al 2009) and also provide information for geodynamic interpretations of the overlying crust. MT data is likely to become increasingly important as more geologists and explorers become interested in the deep earth.…”

Section: Magnetotelluric Surveysmentioning

confidence: 99%

New government geophysics from the Onshore Energy Security Program

Stolz

2012

ASEG Extended Abstracts

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Lithospheric geometry of the Wopmay orogen from a Slave craton to Bear Province magnetotelluric transect

Cited by 61 publications

References 102 publications

A Paleoproterozoic Andean-type iron oxide copper-gold environment, the Great Bear magmatic zone, Northwest Canada

A Paleoproterozoic Andean-type iron oxide copper-gold environment, the Great Bear magmatic zone, Northwest Canada

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

New government geophysics from the Onshore Energy Security Program

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