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TitleChronostratigraphy of the Hottah terrane and Great Bear Magmatic Zone of Wopmay Orogen, Canada, and exploration of a terrane translation model
AuthorOotes, L; Davis, W JORCID logo; Jackson, V; van Breemen, O
SourceCanadian Journal of Earth Sciences vol. 52, 2015 p. 1062-1092, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20053
Alt SeriesEarth Sciences Sector, Contribution Series 20140066
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia; Alberta; Northwest Territories; Saskatchewan
NTS96; 86; 95; 85; 94; 84
AreaGreat Bear Lake Magamatic Zone; Canada
Lat/Long WENS-125.0000 -100.0000 63.0000 55.0000
Subjectstectonics; geochronology; geochemistry; stratigraphy; uranium lead dates; zircon dates; plate tectonics; subduction zones; Hottah terrane; Wopmay orogen; Bell Island Bay Group
Illustrationslocation maps; photographs; tables; diagrams; graphs
ProgramGEM: Geo-mapping for Energy and Minerals Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)
Released2015 12 01
AbstractThe 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.
Hottah evolved exotic to the Archean Slave craton. However Hottah shares a temporal history with a number of terranes preserved in the relict Nunavutia continent and burgeoning Nuna supercontinent, to the south and east. A terrane translation model is suggested where Hottah evolved above a one-sided subduction system with a parentage equivalent to those terranes. This subduction zone underwent tectonic switching and Hottah ruptured off at ca. 1905 Ma and translated northward where it arrived adjacent to the Coronation margin at ca. 1880 Ma. This terrane translation model may be a viable alternative to collision models in other Precambrian terranes that have peri-cratonic attributes.
Summary(Plain Language Summary, not published)
The Wopmay orogen, located in the Northwest Territories, northwest of Yellowknife, is a geological region that formed approximately 1.8 to 2.0 billion years ago. The region hosts a number of past-producing mines including Port Radium and Terra, and is prospective for multiple commodities including copper, gold and uranium. The geology of the area is comparable to more recent geological environments such as the Andes where subduction-related volcanic and intrusive rocks host abundant mineral deposits. This paper presents new geological, geochemical and geochronological data for the Hottah terrane, an important element of Wopmay orogen, that are utilized to reconstruct the early geological history of the area. A modified geological model is presented that provides a regional context for mineral exploration in the area.

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