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

• Published in: Canadian Journal of Earth Sciences
• Main Authors: Ootes, Luke, Davis, William J., Jackson, Valerie A., van Breemen, Otto
• Other Authors: Corfu, Fernando
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2015
• Subjects: Andreas; Baja; Bell Island; Canada; Island Bay; Rivera
• Online Access: http://dx.doi.org/10.1139/cjes-2015-0026; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2015-0026; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2015-0026

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 ...