The Snowbird Tectonic Zone (STZ) is a geological structure in the western Canadian Shield which forms a geophysical boundary between the Hearne Craton and the south-west arm of the

Rae Craton 250px, North America cratons and basement rock. The Rae Craton is an Archean craton located in northern Canada north of the Superior Craton. Ungava Peninsula The Ungava Peninsula, situated on the northeast portion of the Canadian Shield, is w ...

. It is enigmatic and has been interpreted as a Proterozoic suture or escape structure, or an Archaean suture reactivated during either the Archaean or Palaeoproterozic. It stretches from the

Canadian Cordillera The Pacific Cordillera, also known as the Western Cordillera or simply The Cordillera, is a top-level physiographic region of Canada, referring mainly to the extensive cordillera system in Western and Northwestern Canada that constitutes the north ...

north-east to Hudson Bay, diagonally crossing

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dak ...

, the Northwest Territories, and Nunavut. It truncates the Taltson Magmatic Zone in

, which suggests an age younger than 1.95 Ga. In the Baker Basin (near Baker Lake, northern STZ) it is overlapped by

lamprophyre Lamprophyres () are uncommon, small-volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks, and small intrusions. They are alkaline silica- undersaturated mafic or ultramafic rocks with high magnesium ...

dykes and volcanics, suggesting a minimum age of 1.85 Ga; however, a younger age (1.84–1.78 Ga) can be inferred from convergence across the STZ in Alberta. interpreted it as part of the Hudsonian orogeny, a collisional event in which microcontinents were accreted to

Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...

around 1.85 Ga. Using U-Pb dating, estimated the timing of

eclogite Eclogite () is a metamorphic rock containing garnet (almandine- pyrope) hosted in a matrix of sodium-rich pyroxene (omphacite). Accessory minerals include kyanite, rutile, quartz, lawsonite, coesite, amphibole, phengite, paragonite, ...

facies metamorphism, a process which require transport to mantle depth, to 1.904 Ga. They, nevertheless, concluded that it remains unclear whether the STZ is a reactivated Archaean structure or a suture documenting the opening and closure of a Proterzoic ocean.

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* * * * Archean volcanism Paleoproterozoic volcanism Volcanism of Alberta Volcanism of the Northwest Territories Volcanism of Nunavut Volcanism of Saskatchewan {{Canada-geology-stub