Geo-Note 2002-14

Geo-Note 2002-14

GEO 2002-14

Sedimentology and Stratigraphy of Middle and Upper Devonian Carbonates in Northern Alberta: A Contribution to the Carbonate-Hosted Pb-Zn (MVT) Targeted Geoscience Initiative

Author(s) Buschkuehle, B.E. Date 2003-07-01

Outcrops of Middle and Upper Devonian carbonates in northern Alberta were examined as part of the Mississippi-Valley-Type ore deposit Targeted Geoscience Initiative (MVT-TGI) that was jointly supported in Alberta by the Alberta Geological Survey and the Geological Survey of Canada between April 1, 2001 and March 31, 2003. The Middle Devonian Methy Formation which is exposed along the Clearwater river consists of fossiliferous dolomitic limestone to dolostone, that was deposited in a moderate to high-energy fore-reef to reef environment. Faulting and minor amounts of saddle dolomite occur close to a reported galena occurrence at Whitemud Falls on the Clearwater River. The Middle Devonian Waterways Formation is best exposed along the Clearwater and north Athabasca Rivers and their tributaries. The basal Firebag Member consists of interbedded fossiliferous limestones and shales that were deposited in an open marine, low to moderate energy setting. The overlying Calumet Member contains intra-stratified shale and fossiliferous limestone banks, which were deposited in a basinal to fore-reef, moderately agitated, setting. The Christina Member consists of marlstone and limestone with fossiliferous banks, that represent occasional storm events in a below wave base depositional setting. The stratigraphically highest Member, the Moberly, contains fossilerous limestones with calcareous shales and is partially dolomitized. It displays storm units and represents a high energy setting transitional between bank/reef and bank margin/fore reef environments. Late diagenetic features are rare to absent in the Waterways Formation. The Upper Devonian Mikkwa and Grosmont Formations were examined at Vermilion Chutes on the Peace River. The Mikkwa Formation changes upward from basal limestones and mud-wackestones to bank and reefal dolostones. The overlying Grosmont Formation changes upward from a dolomitic bank to a reefal dolostone. Minor calcite and saddle dolomite cements are present.

Buschkuehle, B.E. (2003): Sedimentology and stratigraphy of middle and Upper Devonian carbonates in northern Alberta: a contribution to the carbonate-hosted Pb-Zn (MVT) targeted geoscience initiative; Alberta Energy and Utilities Board, EUB/AGS Geo-Note 2002-14, 20 p.