Recognition of wave-influenced deltaic and bay-margin sedimentation, Bluesky Formation, Alberta

Abstract The late Aptian to early Albian Bluesky Formation of Alberta is characterized by complex vertical and lateral associations of siliciclastic sediments deposited during overall transgression of the Boreal sea. As the Bluesky Formation is host to substantial subsurface bitumen deposits of the Peace River oil sands, a refined understanding of vertical and lateral facies distributions is essential for exploration and exploitation activity. To aid in achieving this goal, high-resolution core logging was completed on a 40 core dataset within Ranges 16–17W5M, and Townships 82–84 (approximately 215 km2). We identify 16 distinct facies comprising 5 facies associations (FA1–FA5). These facies associations include: 1) FA1 – Wave-dominated, fluvially influenced embayment delta; 2) FA2 – Fluvially-dominated, tidally-influenced distributary channel; 3) FA3 – Fluvially and tidally influenced delta; 4) FA4 – Marine-embayment shoreface to offshore; and, 5) FA5 – Mixed energy estuary. The evolution of these facies associations suggest periodic progradation within an overall back-stepping, transgressive, marine-embayment system. Through combination of sedimentary and ichnological characteristics, this research has led to the identification of wave-influenced deltaic and marine-embayment sedimentary environments previously un-documented within the Peace River oil sands. Additionally, proximal-distal depositional trends obscured by the complex facies distributions were identifiable using ichnological criteria. It is intended that the sedimentological and ichnological characteristics identified herein will aid in the recognition of similar embayment-type settings in other ancient datasets.