ALBERT

Description: The subglacial geology in Wilkes Land, East Antarctica is masked by thick ice and remains largely unexplored. Yet the underlying crustal architecture records evidence of repeated supercontinent cycles and provides the geological template for the evolution of the Antarctic Ice Sheet. Sediment eroded from under the ice is ultimately deposited in the ocean, such that marine sediment can be used to characterise the adjacent subglacial geology. We use detrital grain morphology, geochemistry and isotopic data from a kasten core to construct a new marine sediment provenance record for the continental slope of central Wilkes Land, and provide new isotopic signatures from proximal coastal outcrops for comparison. We establish the source rock type, age and provenance, and the associated transport pathways and mechanisms responsible for detrital sediment input from 23.5 ka to present. A principally igneous source is revealed with dominant age populations between c. 1200-1100 Ma and c. 1600-1300 Ma, characteristic of the proximal Banzare, Nuyina and Wilkes Provinces. The detrital geochronology suggests no change in sediment provenance over the last 23.5 ka, despite major ice sheet retreat during this time. A minor c. 700-500 Ma detrital age population unknown from the central Wilkes region was likely transported westward via icebergs to the core site. These findings broadly correspond with earlier interpretations of the subglacial geology and erosion rates at the base of the ice sheet predicted from two ice sheet models, demonstrating the value of sediment provenance studies for uncovering proximal subglacial geology and reconstructing past ice sheet configurations.

Description: This comprises supplementary data from "Expression of Millennial-Scale Antarctic Warming Events in the Southern Ocean." and represents 14 sediment records from the Southern Ocean, 30°S - 60°S. These records have had their age models recalibrated and tied to EDC dD on the AICC2012 timescale to facilitate comparison across basins, and in order to create SST stacks for the Atlantic-Indian, Pacific, and Southern Oceans.

Description: Downcore measurements of iceberg-rafted debris (IBRD) flux and biogenic silica concentrations in kasten core IN2017_V01-A042-KC14 from the continental slope of central Wilkes Land, East Antarctica. The IBRD flux was calculated by multiplying the coarse sand fraction by the linear sedimentation rate and the dry bulk density at each depth interval along the core. All of these values are shown. The biogenic silica concentration is shown as a percentage.

Description: Pb-Pb ratios, ages and trace element data from detrital feldspars in kasten core IN2017_V01-A042-KC14 from the continental slope of central Wilkes Land, East Antarctica and in-situ feldspars from coastal basement rocks in East Antarctica (Chick Island and Balaena Islets). All data was obtained using laser ablation-inductively-couple plasma mass spectrometry (LA-ICPMS). All ratios and ages are shown with one standard error.

Description: Increased export production (EP) in the Subantarctic Zone (SAZ) of the Southern Ocean due to iron fertilisation has been proposed as a key mechanism for explaining carbon drawdown during the last glacial maximum (LGM). This work reconstructs marine EP since the LGM at four sites around New Zealand. For the first time in this region, 230-Thorium-normalised fluxes of biogenic opal, carbonate, excess barium, and organic carbon are presented. In Subtropical Waters and the SAZ, these flux variations show that EP has not changed markedly since the LGM. The only exception is a site currently north of the subtropical front. Here we suggest the subtropical front shifted over the core site between 18 and 12 ka, driving increased EP. To understand why EP remained mostly low and constant elsewhere, lithogenic fluxes at the four sites were measured to investigate changes in dust deposition. At all sites, lithogenic fluxes were greater during the LGM compared to the Holocene. The positive temporal correlation between the Antarctic dust record and lithogenic flux at a site in the Tasman Sea shows that regionally, increased dust deposition contributed to the high glacial lithogenic fluxes. Additionally, it is inferred that lithogenic material from erosion and glacier melting deposited on the Campbell Plateau during the deglaciation (18-12 ka). From these observations, it is proposed that even though increased glacial dust deposition may have relieved iron limitation within the SAZ around New Zealand, the availability of silicic acid limited diatom growth and thus any resultant increase in carbon export during the LGM. Therefore, silicic acid concentrations have remained low since the LGM. This result suggests that both silicic acid and iron co-limit EP in the SAZ around New Zealand, consistent with modern process studies.

Description: Neodymium and strontium isotope compositions from four marine Kasten cores recovered from the continental rise of central Wilkes Land, East Antarctica.

Description: Zr/Rb and K/Ca elemental x-ray fluorescence ratios from four marine Kasten cores recovered from the continental rise of central Wilkes Land, East Antarctica.

Description: Bulk acid insoluble organic carbon ages from core IN2017_V01-A042-KC14 with calibrated ages shown and their respective depth intervals. Ages were calibrated using Matcal 2.41 and a constant marine reservoir age of 917.5 years.