4D Antarctica: a new effort aims to help bridge the gap between Antarctic crust and lithosphere structure and geothermal heat flux

Seismology, satellite-magnetic and aeromagnetic data, and sparse MT provide the only available geophysical proxies for large parts of Antarctica\u2019s Geothermal Heat Flux (GHF) due to the sparseness of direct measurements. However, these geophysical methods have yielded significantly different GHF estimates. This restricts our knowledge of Antarctica\u2019s contrasting tectono-thermal provinces and their influence on subglacial hydrology and ice sheet dynamics. For example, some models derived from aeromagnetic data predict remarkably high GHF in the interior of the West Antarctic Rift System (WARS), while other satellite magnetic and seismological models favour instead a significantly colder rift interior but higher GHF stretching from the Marie Byrd Land dome towards the Antarctic Peninsula, and beneath parts of the Transantarctic Mountains. Reconciling these differences in West Antarctica is imperative to better comprehend the degree to which the WARS influences the West Antarctic Ice Sheet, including thermal influences on GIA. Equally important, is quantifying geothermal heat flux variability in the generally colder but composite East Antarctic craton, especially beneath its giant marine-based basins. Here we present a new ESA project- 4D Antarctica that aims to better connect international Antarctic crust and lithosphere studies with GHF, and assess its influence on subglacial hydrology by analysing and modelling recent satellite and airborne geophysical datasets. The state of the art, hypotheses to test, and methodological approaches for five key study areas, including the Amundsen Sea Embayment, the Wilkes Subglacial Basin and the Totten catchment, the Recovery and Pensacola-Pole Basins and the Gamburtsev Sublgacial Mountains/East Antarctic Rift System are highlighted

Recent magnetic views of the Antarctic lithosphere

Magnetic anomaly investigations are a key tool to help unveil subglacial geology, crustal architecture and the tectonic and geodynamic evolution of the Antarctic continent. Here, we present the second generation Antarctic magnetic anomaly compilation ADMAP 2.0 (Golynsky et al., 2018), that now includes a staggering 3.5 million line-km of aeromagnetic and marine magnetic data, more than double the amount of data available in the first generation effort. All the magnetic data were corrected for the International Geomagnetic Reference Field, diurnal effects, high-frequency errors and leveled, gridded,and stitched together. The new magnetic anomaly dataset provides tantalising new views into the structure and evolution of the Antarctic Peninsula and the West Antarctic Rift System within West Antarctica, and Dronning Maud Land, the Gamburtsev Subglacial Mountains, the Prince Charles Mountains, Princess Elizabeth Land, and Wilkes Land in East Antarctica, as well as key insights into oceanic gateways. Our magnetic anomaly compilation is helping unify disparate regional geologic and geophysical studies by providing larger-scale perspectives into the major tectonic and magmatic processes that affected Antarctica from Precambrian to Cenozoic times, including e.g. the processes of subduction and magmatic arc development, orogenesis, accretion, cratonisation and continental rifting, as well as continental margin and oceanic basin evolution. The international Antarctic geomagnetic community remains very active in the wake of ADMAP 2.0, and we will showcase some of their key ongoing study areas, such as the South Pole and Recovery frontiers, the Ross Ice Shelf, Dronning Maud Land and Princess Elizabeth Land

New Magnetic Anomaly Map of the Antarctic

The second generation Antarctic magnetic anomaly compilation for the region south of 60 degrees S includes some 3.5 million line-km of aeromagnetic and marine magnetic data that more than doubles the initial map's near-surface database. For the new compilation, the magnetic data sets were corrected for the International Geomagnetic Reference Field, diurnal effects, and high-frequency errors and leveled, gridded, and stitched together. The new magnetic data further constrain the crustal architecture and geological evolution of the Antarctic Peninsula and the West Antarctic Rift System in West Antarctica, as well as Dronning Maud Land, the Gamburtsev Subglacial Mountains, the Prince Charles Mountains, Princess Elizabeth Land, and Wilkes Land in East Antarctica and the circumjacent oceanic margins. Overall, the magnetic anomaly compilation helps unify disparate regional geologic and geophysical studies by providing new constraints on major tectonic and magmatic processes that affected the Antarctic from Precambrian to Cenozoic times.Korea Polar Research Institute (KOPRI) programs, PM15040 and PE17050Germany's AWI/Helmholtz Center for Polar and Marine ResearchFederal Institute for Geosciences and Natural ResourcesBritish Antarctic Survey/Natural Environmental Research CouncilItalian Antarctic Research ProgrammeRussian Ministry of Natural ResourcesU.S. National Science Foundation and National Space and Aeronautics AdministrationAustralian Antarctic Division and Antarctic Climate & Ecosystem Cooperative Research CentreFrench Polar InstituteGlobal geomagnetic observatories network (INTERMAGNET

Bedrock erosion surfaces record former East Antarctic Ice Sheet extent

East Antarctica hosts large subglacial basins into which the East Antarctic Ice Sheet (EAIS) likely retreated during past warmer climates. However, the extent of retreat remains poorly constrained, making quantifying past and predicted future contributions to global sea level rise from these marine basins challenging. Geomorphological analysis and flexural modeling within the Wilkes Subglacial Basin is used to reconstruct the ice margin during warm intervals of the Oligocene–Miocene. Flat‐lying bedrock plateaus are indicative of an ice sheet margin positioned >400–500 km inland of the modern grounding zone for extended periods of the Oligocene–Miocene, equivalent to a 2 meter rise in global sea level. Our findings imply that if major EAIS retreat occurs in the future, isostatic rebound will enable the plateau surfaces to act as seeding points for extensive ice rises, thus limiting extensive ice margin retreat of the scale seen during the early EAIS

Piezomagnetic effects induced by artificial sources at Mt. Vesuvius (Italy): preliminary results of an experimental survey

In order to put new constrains on magnetic effects associated with mechanical stresses, high frequency monitoring of the geomagnetic field was carried out during a seismic tomography experiment (TOMOVES'96 project) at Mt. Vesuvius. Eight proton precession and one Cesium magnetometers were installed along a profile on the SW flank of the volcano to observe possible magnetic changes induced by explosions. Measurements were performed at different sampling frequencies (10 Hz, 0.5 Hz and 0.1 Hz). A remarkable change in the intensity of the magnetic field was observed in only one case. The magnetic transient lasted 12-13 min, reaching the maximum amplitude of slightly less than 15 nT

Piezomagnetic effects induced by artificial sources at Mt. Vesuvius (Italy): preliminary results of an experimental survey

In order to put new constrains on magnetic effects associated with mechanical stresses, high frequency monitoring of the geomagnetic field was carried out during a seismic tomography experiment (TOMOVES'96 project) at Mt. Vesuvius. Eight proton precession and one Cesium magnetometers were installed along a profile on the SW flank of the volcano to observe possible magnetic changes induced by explosions. Measurements were performed at different sampling frequencies (10 Hz, 0.5 Hz and 0.1 Hz). A remarkable change in the intensity of the magnetic field was observed in only one case. The magnetic transient lasted 12-13 min, reaching the maximum amplitude of slightly less than 15 nT