Preliminary Stratigraphic Framework for Selected Kimberlites in the Buffalo Head Hills Region, North-Central Alberta

A preliminary stratigraphic framework is presented for the uppermost Cretaceous strata of the southeastern Buffalo Head Hills, north-central Alberta. The stratigraphy is based on wireline log picks from over 230 oil and gas well logs in the area, and the study of sedimentary rock cores from 14 drillholes that evaluated 10 separate kimberlite targets within the Buffalo Head Hills kimberlite field. These descriptions and interpretations will serve as a basis for stratigraphic correlation of individual and inter-field kimberlite targets, and provide a better understanding of kimberlite-hostrock relationships required to assess potential mechanisms of kimberlite emplacement. The oldest sedimentary rocks in the area belong to the Albian Fort St. John Group. The youngest sedimentary rocks in the area belong to the Campanian Wapiti Group and are apparent in a stratigraphic study hole drilled collaboratively by the Geological Survey of Canada and Alberta Geological Survey. The kimberlites appear to be hosted within lower Cenomanian to Campanian strata, time equivalent to the Shaftesbury and Dunvegan formations, Smoky Group and Wapiti Formation.

Sedimentological interpretation of the selected cores suggest uppermost Cretaceous Buffalo Head Hills paleoenvironments ranged from lower shoreface below wave base to tidal flat/channel to fluvial (continental) environments. Based on radiometric emplacement ages and palynostratigraphic determination of kimberlite and mudstone in the Buffalo Head Hills kimberlite field, it is suggested that the tidal flat/channel to fluvial (continental) environments were predominant during emplacement of the majority of the pipes in the Buffalo Head Hills.