Abstract

The Jurassic shelf shales and sandstones of northern Yukon and adjacent Northwest Territories, including the subsurface Mackenzie Delta, are probably entirely derived from the craton to the south and southeast (Bug Creek Group; Kingak, Husky, North Branch, and Porcupine River Formations). The ‘Lower Schist Division’ of central Yukon is a southerly extension of the Kingak Shale of the north.

Phosphatic and cherty limestone and shale facies occur in the lower part of the Jurassic platform and miogeoclinal Fernie Formation of western Alberta and eastern British Columbia. Overlying Fernie units are dominantly shale with minor sandstones. Upper Jurassic sandstones of the lower Kootenay Group and lower Nikanassin and basal Monteith Formations record the change of sediment source from east to west resulting from early uplift of the Columbian Orogen and subsidence of the foredeep to its east.

Middle and Upper Jurassic shales, carbonates, evaporites, and sandstones (Watrous, Gravelbourg, Shaunavon, Vanguard and equivalent Formations) were deposited in a depositionally restricted epicratonic setting in the Williston Basin in southern Alberta, Saskatchewan and Manitoba. Early phases of the Columbian Orogeny are represented in the westernmost Williston Basin by the Upper Jurassic Swift Formation.

Similar transgressive-regressive events throughout the craton-related western Canadian Jurassic indicate unified tectonic and/or eustatic activity along the northwestern North American cratonic margin in Jurassic times. Greater standstone developments in northern Yukon, and as yet poorly defined evidence in the Peace River area suggest more significant tectonic activity in the northern parts of the area than in the south.

The Jurassic rocks of Alberta, southern Saskatchewan and Manitoba are significant host rocks and source rocks for oil and gas deposits. Coal deposits are mined in Upper Jurassic beds of southwestern Alberta and southeastern British Columbia. Phosphates have been prospected in the Jurassic of southeastern British Columbia, and gypsum is mined in southern Manitoba.