Description: The Antarctic Digital Magnetic Anomaly Project (ADMAP) is an Expert Group of the Scientific Committee on Antarctic Research (SCAR). ADMAP compiles and publishes compilations of near surface magnetic anomaly data south of 60°S. Its two most recent compilations are referred to as ADMAP2B and ADMAP2S. ADMAP2B shows near-surface data only, with large gaps. ADMAP2S fills the gaps with satellite-derived data. Both products are freely available, but until now only for proprietary and/or custom software and with a custom map projection that is not widely used outside of the group. This contribution offers both ADMAP2B and ADMAP2S gridded data products in the widely used geotiff, netcdf, and kmz grid formats, and projected into the well known geodetic longitude-latitude and SCAR's recommended WGS-84 Antarctic Polar Stereographic system. These grids are suitable for use in a wide range of applications, including the widely-used free and open source products QGIS, Generic Mapping Tools, and Google Earth.

Description: High-resolution palaeotopographic and -bathymetric models of the Southern Ocean and the Antarctic continent facilitate detailed investigation of past ice sheet and ocean circulation development from land to sea, which is essential for robust reconstructions of the paleoclimate, palaeocryosphere, and palaeoceanography. These important boundary conditions have been newly reconstructed based on all available geophysical and geological data and merged together to form complete grids of the Southern Ocean and Antarctica. For detailed information on the reconstructions, please refer to Paxman et al. (2019) and Hochmuth et al. (2020) for the palaeotopography and the palaeobathymetry, respectively. For further information on the merging process, please see the attached readme document. We present a compilation of the merged palaeotopography and palaeobathymetry for five key time slices in the Cenozoic development of the Antarctic continent and the Southern Ocean: (i) Eocene/Oligocene Boundary (34 Ma), (ii) Oligocene/Miocene Transition (23 Ma), (iii) middle Miocene (14 Ma), (iv) early Pliocene (5 Ma), and (v) Pliocene/Pleistocene Boundary (2.6 Ma). Note: The primary authors of the original publications, G. Paxman and K. Hochmuth are equally contributing joint first authors of this dataset compilation.

Description: The East Antarctic Ice Sheet (EAIS) is underlain by a series of low‐lying subglacial sedimentary basins. The extent, geology, and basal topography of these sedimentary basins are important boundary conditions governing the dynamics of the overlying ice sheet. This is particularly pertinent for basins close to the grounding line wherein the EAIS is grounded below sea level and therefore potentially vulnerable to rapid retreat. Here we analyze newly acquired airborne geophysical data over the Pensacola‐Pole Basin (PPB), a previously unexplored sector of the EAIS. Using a combination of gravity and magnetic and ice‐penetrating radar data, we present the first detailed subglacial sedimentary basin model for the PPB. Radar data reveal that the PPB is defined by a topographic depression situated ~500 m below sea level. Gravity and magnetic depth‐to‐source modeling indicate that the southern part of the basin is underlain by a sedimentary succession 2–3 km thick. This is interpreted as an equivalent of the Beacon Supergroup and associated Ferrar dolerites that are exposed along the margin of East Antarctica. However, we find that similar rocks appear to be largely absent from the northern part of the basin, close to the present‐day grounding line. In addition, the eastern margin of the basin is characterized by a major geological boundary and a system of overdeepened subglacial troughs. We suggest that these characteristics of the basin may reflect the behavior of past ice sheets and/or exert an influence on the present‐day dynamics of the overlying EAIS.

Description: The Antarctic continent and its surrounding Southern Ocean are a key component of our planet’s climate system. Since the Eocene/Oligocene Boundary (34 Ma) the Antarctic region has undergone tremendous topographical change on the continent and in the oceanic realm. The massive erosion on the continent by the Antarctic ice sheets and the resulting glacial deposition within the Southern Ocean have shaped our modern maps of the Southern hemisphere. Detailed, high-resolution reconstructions of the palaeotopography and palaeobathymetry shed light on crucial periods in the development of the Antarctic ice sheets as well as the Southern Ocean. This includes e.g. the establishment of the modern circum-polar current system, the pathways of modern and ancient glacial systems as well as the role of the continental shelves in ice sheet stability. Most recent reconstructions of the paleotopography (Paxman et al. 2019) and paleobathymetry (Hochmuth et al. 2020) used all available geophysical as well as geological and borehole data to produce high-resolution maps (0.1 deg) of key time slices of the Southern Ocean evolution. The combined palaeobathymetry and palaeotopography allows seamless land-to-ocean studies including analysis of ice sheet behaviour and erosion and associated depositional cycles. The five time slices presented span from the onset of continental glaciation in Antarctica (34 Ma) to the warmer climates of the Miocene and early Pliocene to the manifestation of modern glacial condition at the Pliocene/Pleistocene Boundary.

Description: The subglacial landscape of Antarctica records and influences the behaviour of its overlying ice sheet. However, in many places, the evolution of the landscape and its control on ice sheet behaviour have not been investigated in detail. Using recently released radio-echo sounding data, we investigate the subglacial landscape of the Evans–Rutford region of West Antarctica. Following quantitative analysis of the landscape morphology under ice-loaded and ice-unloaded conditions, we identify 10 flat surfaces distributed across the region. Across these 10 surfaces, we identify two distinct populations based on clustering of elevations, which potentially represent remnants of regionally coherent pre-glacial surfaces underlying the West Antarctic Ice Sheet (WAIS). The surfaces are bounded by deeply incised glacial troughs, some of which have potential tectonic controls. We assess two hypotheses for the evolution of the regional landscape: (1) passive-margin evolution associated with the break-up of the Gondwana supercontinent or (2) an extensive planation surface that may have been uplifted in association with either the West Antarctic Rift System or cessation of subduction at the base of the Antarctic Peninsula. We suggest that passive-margin evolution is the most likely of these two mechanisms, with the erosion of glacial troughs adjacent to, and incising, the flat surfaces likely having coincided with the growth of the WAIS. These flat surfaces also demonstrate similarities to other identified surfaces, indicating that a similar formational process may have been acting more widely around the Weddell Sea embayment. The subsequent fluctuations of ice flow, basal thermal regime, and erosion patterns of the WAIS are therefore controlled by the regional tectonic structures.