Fjord stratigraphy and processes – evidence from the NE Atlantic Fensfjorden system

Fjords commonly hold sediment basins with high temporal resolution that mirror land‐ and marine‐based processes and depositional environments during a glacial–interglacial cycle. Here, we present TOPAS seismic profiles, with a vertical resolution of <30 cm, bathymetric records and a gravity core from Fensfjorden, west Norway, which allow a detailed study of sedimentary processes and depositional environments in a NE Atlantic fjord system. Fensfjorden hosts a sediment volume of 0.70 km3 and the sediment basins evolved reach a maximum thickness of 100 m. The basins are characterized by a lower acoustically well‐laminated glacimarine unit, of Allerød and Younger Dryas age. This unit is overlain by several acoustically transparent lenses, interpreted to be slide debrites. We suggest these slide debrites to be a result of recurrent mass failures that occurred between 11 500 and 2100 cal a BP. A thin late Holocene hemipelagic unit drapes the slide debrites. During the late Holocene the sedimentation rates in Fensfjorden decreased from 0.110 to 0.040 cm a−1 and two turbidity currents occurred in the 2040–1190 cal a BP time period. This ability to map fjord processes in more detail has, furthermore, made it possible to revise the established stratigraphical framework for NE Atlantic fjords.