Foraminiferal biofacies succession in the late Quaternary Fraser River delta, British Columbia

Abstract

Three foraminiferal biofacies indicating distinct depositional environments were identified in cores FD87A1 and FD88A1 from the Fraser River delta. The Cassidulina- Islandiella biofacies, in the basal portion of Core FD87A1 (347.5-367 m), was probably deposited in about 100-200 m of normal-salinity, cold water during the penultimate glaciation (Late Wisconsinan or older). The Cribroelphidium bartletti biofacies, identified in Core FD87A1 (197-256 m), may have been deposited in water depths of less than 150 m during the Everson Interstade. The Cribroelphidium excavarum biofacies, found in both Core FD87A1 (64-182.7 m) and Core FD88A1 (76.2-122.3 m) is associated with ancestral Strait of Georgia Holocene prodelta and delta slope sediments that accumulated in water depths of less than 200 m. The high frequency of Cribroefphidium excavatum in these sediments indicates depressed salinities during deposition (6 and 12 ka). Similar conditions are found today in the Strait of Georgia where the salinity range is 27-310/00.