A marine survey in Prydz Bay, provides an unparalleled view of glacigenic and marine sedimentation across Prydz Channel and Amery Depression during the Late Quaternary. Gravity cores and a suite of eight radiocarbon dates indicate that the Late Wisconsin Glacial Maximum (LGM) was associated with grounding of a palaeo-ice shelf along the periphery of Prydz Channel. Deposition in front of the grounding line was dominated by ice-rafting. A granulated facies, containing angular clay and diamicton clasts, was produced by a combination of regelation freezing, near to the grounding line, and remelting of this basal debris in the sub-ice shelfsetting. Beneath these LGM marine deposits lie two key beds of diatom ooze that are distinct in size sorting and Pliocene diatoms. These "interstadial" units can be traced across most ofthe Prydz Channel, and are underlain by additional glacial marine units. Debris related to the Lambert Deep is distinct from detritus from eastern Prydz Bay and deposition ofthese two sources within the channel oscillated during the LGM. We suggest that coastal drainage systems contributed to a limited glaciation of the shelf during the LGM, rather than direct outflow via the Lambert /Amery system. It is proposed that shelf-wide glaciation is related to the duration ofglacial sea level lowstands rather than the absolute magnitude of eustatic fall during such episodes.

Abstract:The Cenozoic glacial history of East Antarctica is recorded in part by the stratigraphy of the Prydz Bay-Lambert Graben region. The glacigene strata and associated erosion surfaces record at least 10 intervals of glacial advance (with accompanying erosion and sediment compaction), and more than 17 intervals of glacial retreat (enabling open marine deposition in Prydz Bay and the Lambert Graben). The number of glacial advances and retreats is considerably less than would be expected from Milankovitch frequencies due to the incomplete stratigraphic record. Large advances of the Lambert Glacier caused progradation of the continental shelf edge. At times of extreme glacial retreat, marine conditions reached > 450 km inland from the modern ice shelf edge. This review presents a partial reconstruction of Cenozoic glacial extent within Prydz Bay and the Lambert Graben that can be compared to eustatic sea-level records from the southern Australian continental margin.

This review assesses the circumpolar occurrence of emerged marine macrofossils and sediments from Antarctic coastal areas in relation to Late Quaternary climate changes. Radiocarbon ages of the macrofossils, which are interpreted in view of the complexities of the Antarctic marine radiocarbon reservoir and resolution of this dating technique, show a bimodal distribution. The data indicate that marine species inhabited coastal environments from at least 35 000 to 20 000 yr BP, during Marine Isotope Stage 3 when extensive iceberg calving created a 'meltwater lid' over the Southern Ocean. The general absence of these marine species from 20 000 to 8500 yr BP coincides with the subsequent advance of the Antarctic ice sheets during the Last Glacial Maximum. Synchronous re-appearance of the Antarctic marine fossils in emerged beaches around the continent, all ofwhich have Holocene marine-limit elevations an order of magnitude lower than those in the Arctic, reflect minimal isostatic rebound as relative sea-level rise decelerated. Antarctic coastal marine habitat changes around the continent also coincided with increasing sea-ice extent and outlet glacial advances during the mid-Holocene. In view ofthe diverse environmental changes that occurred around the Earth during this period, it is suggested that Antarctic coastal areas were responding to a mid-Holocene climatic shift associated with the hydrological cycle. This synthesis of Late Quaternary emerged marine deposits demonstrates the application of evaluating circum-Antarctic phenomena from the glacial-terrestrialmarine transition zone.

The eastern Coral Sea is a poorly explored area at the northeastern corner of the Australian 24 Tectonic Plate, where interaction between the Pacific and Australian plate boundaries, and 25 accretion of the world's largest submarine plateau-the Ontong Java Plateau-has resulted in 26 a complex assemblage of back-arc basins, island arcs, continental plateaus and volcanic 27 products. This study combines new and existing magnetic anomaly profiles, seafloor fabric 28 from swath bathymetry data, Ar-Ar dating of E-MORB basalts, palaeontological dating of 29 carbonate sediments, and plate modelling from the eastern Coral Sea. Our results constrain 30 commencement of the opening of the Santa Cruz Basin and South Rennell Trough to c. 48 31 Ma and termination at 25-28 Ma. Simultaneous opening of the Melanesian Basin/Solomon 32 Sea further north suggests that a single > 2,000 km long back-arc basin, with at least one 33 triple junction existed landward of the Melanesian subduction zone from Eocene-Oligocene 34 times. The cessation of spreading corresponds with a reorganization of the plate boundaries 35 in the area and the proposed initial soft collision of the Ontong Java Plateau. The correlation 36 between back-arc basin cessation and a widespread plate reorganization event suggests that 37 back-arc basins may be used as markers for both local and global plate boundary changes.

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Several grounding zone wedges were left on the floor and flanks of Prydz Channel in western Prydz Bay by the Lambert Glacier during the last glacial cycle. Seismic profiles indicate that vertical accretion at the glacier bed was the most important depositional process in forming the wedges, rather than progradation by sediment gravity flows. Sidescan sonographs reveal extensive development of flutes on the sea floor inshore from the wedges, indicating deformable bed conditions beneath the ice. The region inshore of the east Prydz Channel wedge features extensive dune fields formed by currents flowing towards the grounding zone. This orientation is consistent with models of circulation beneath ice shelves in which melting at the grounding line generates plumes of fresher water that rise along the base of the ice shelf, entraining sea water into a circulation cell. The Lambert Deep is surrounded by a large composite ridge of glacial sediments. Internal reflectors suggest formationmostly by subglacial accretion. Thesea floorin theLambert Deep lacks dune fieldsandshows evidence of interspersed subglacial cavities and grounded ice beneath the glacier. The absence of bedforms reflects sea floor topography that would have inhibited the formation of energetic melt water-driven circulation.

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We use a Generalized Additive Model (GAM) to provide the first winter sea ice concentration record from two cores located within the southwest Pacific sector of the Southern Ocean. To compliment the application of GAM, a time series analysis on satellite records of sea ice concentration data was used to extend the standard 13.25 year time series used for paleoceanography. After comparing GAM sea ice estimates with previously published paleo sea ice data we then focus on a new paleo winter sea ice record for marine sediment core E27-23 (59°37.1'S, 155°14.3'E), allowing us to provide a more comprehensive view of winter sea ice dynamics for the southwest Pacific Ocean. The paleo winter sea ice concentration estimates provide the first suggestion that winter sea ice within the southwestern Pacific might have expanded during the Antarctic Cold Reversal. Throughout the Holocene, core E27-23 documents millennial scale variability in paleo winter sea ice coverage within the southwest Pacific. Holocene winter sea ice expansion may have resulted from the Laurentide Ice Sheet deglaciation, increased intensity of the westerly winds, as well as a northern migration of the Subtropical and/or Sub-Antarctic Fronts. Brief consideration is given to the development of a paleo summer sea ice proxy. We conclude that there is no evidence that summer sea ice ever existed at core sites SO136-111 and E27-23 over the last 220 and 52,000 years, respectively.