Geophysical Survey of the Thick, Expanded Sedimentary Fill of the New-Born Crane Fjord (Former Larsen B Ice Shelf, Antarctica

Integrated geophysical data recorded during cruise NBP0603 revealed the setting and the infill history of the newly-created Crane Glacier Fjord (Exasperation Inlet, Eastern Antarctic Peninsula). Originated by the 15 km retreat of the Crane Glacier after the Larsen B ice shelf collapse, the fjord shows three ponded basins at its floor, imaged in detail by a 12 kHz multibeam echosounder. In the lowest basin, sub-bottom profiling and single channel seismic revealed a 40 m thick, well-layered and unconsolidated fill. Its upper part, as confirmed by a 2.7 m core collected in the area, was interpreted as the result of the accelerated ice discharge from the glacier during the ice shelf break-up. The rest of the fill was regarded as the result of 30 years long sub-glacial lake sedimentation, suggesting that the glacier behaviour was affected not only by the Larsen-B ice shelf collapse, but also by regional ice shelves dynamics