Clues to Glacial Regime and Bottom-current Changes in the Northwestern Ross Sea

Abstract

The sedimentary record in polar continental margins provides useful insights into the glacial regime and bottom-current changes during the past glacial and interglacial periods. Many of the previous seismic stratigraphic studies have been conducted over the Ross Sea embayment to reveal the Cenozoic Antarctic glacial history. Due to lack of data, however, there have been much less studies that could provide a more continuous record of ice-sheet dynamics and bottom-current activity on the Ross Sea slope and rise. Here, we present a seismic stratigraphic analysis of sediments in the Joides Basin mouth and Central Basin, northwestern Ross Sea using the new and existing seismic and adjacent drill site data. The seismic profiles and sequence maps indicate that gravity sedimentation processes dominated the Central Basin infill, and then downslope sediment supply to the lower slope and rise was gradually reduced through the late Neogene and Quaternary. The bottomcurrent-controlled sedimentary features that may initiated on the surrounding banks and slopes since the mid-Miocene were overlain by glacigenic debris flows near the Joides Basin mouth after the late Pliocene. These results would indicate that the Antarctic glacial regime was evolved toward a cooler, less erosive through the late Neogene and Quaternary and bottom-current activity was diminished near the paleo-shelf edge after the late Pliocene in the northwestern Ross Sea margin.