Seismic stratigraphy of the Central Basin in northwestern Ross Sea slope and rise, Antarctica: Clues to the late Cenozoic ice-sheet dynamics and bottom-current activity

The results of seismic stratigraphic analysis indicate that gravity sedimentation processes dominated the Central Basin infill up to the mid-Miocene, and then downslope sediment supply gradually diminished through the late Miocene and Quaternary, likely reflecting a shift toward a cooler, less erosive glacial regime change. Since the late Pliocene, a topset-truncated glacial prograding wedge developed in the upper continental slope at the mouth of the Joides Basin and the sediment depocenter was shifted from the basin floor to the upper slope, suggesting the more persistent occurrence of grounded ice sheets on the outer continental shelf. Meanwhile, persistent along-slope bottom-current processes formed contourites on the slope and over the crests of banks surrounding the Central Basin since the mid-Miocene. In the late Pliocene, the contourites that formed off the Joides Basin mouth were overlain by glaciogenic debris flows, while the growth of contourites continued over and along the flanks of banks, farther to the north. This suggests that along-slope bottom-current processes near the Joides Basin mouth were diminished or dominated by the glacial discharge to the continental shelf edge. The sediment stacking patterns differ between the Joides/Central Basins and the Drygalski/Adare Basins located on the westernmost Ross Sea margin, suggesting that distinctive glacial/interglacial behavior of the former grounded ice streams and sediment supplies in the troughs feeding these basins were largely controlled by the paleo-seafloor morphology of the western Ross Sea continental shelf.