Abstract

Deposited immediately following the Montney lowstand turbidites, the moderate porosity and low permeability siltstones of the Montney D1 and D2 horizons are important exploration targets. Eight lithofacies are identified, based on detailed sedimentological and ichnological observations. Deposition took place in the distal offshore to offshore-transition area. Linear sourced turbidity currents are thought to have been the most important mechanism for sediment deposition. An arid coastline, with numerous ephemeral river systems that transported large amounts of sediment to the coast during storms, created an over steepened shoreface profile which would have been prone to mass wasting events.

The study area overlies the southeastern extension of the Fort St. John Graben complex, and structural reactivations throughout the deposition of the D1 and D2 horizons played a major role in controlling the location of major sediment accumulations. The D1-D2 transition is characterized by the presence of silty shale beds. The presence of appreciable amounts of clay in the Montney is rare except for a few areas. These areas are interpreted to have been deposited under the influence of perennial deltaic systems. During the D1-D2 transition, silty shale beds indicate that there was a perennial river system running through the Hines Creek Graben sourcing the clays.