A document by Alan R.A. Aitken. Click on the document to view its contents.

Direct geological information in Antarctica is limited to ice free regions along the coast, high mountain ranges or isolated nunataks. Therefore, indirect methods are required to reveal subglacial geology and heterogeneities in crustal properties, which are critical steps towards interpreting geological history. We present a 3D crustal model of density and susceptibility distribution in the Wilkes Subglacial Basin and the Transantarctic Mountains (TAM) based on joint inversion of airborne gravity and magnetic data. The applied “variation of information” technique enforces a coupling between gravity and magnetic sources to give an enhanced inversion result. Our model reveals a large-scale body located in the interior of the Wilkes Subglacial Basin interpreted as a batholithic intrusive structure, as well as a linear dense body at the margin of the Terre Adélie Craton. Density and susceptibility relationships are used to inform the interpretation of petrophysical properties and the reconstruction of the origin of those crustal blocks. The petrophysical relationship indicates that the postulated batholitic intrusion is granitic, but independent from the Granite Harbour Igneous Complex previous described in the TAM area. Emplacement of a large volume of intrusive granites can potentially elevate local geothermal heat flow significantly. Finally, we present a tectonic evolution sketch based on the inversion results, which includes development of a passive continental margin with seaward dipping basalt horizons and magmatic underplating followed by two distinct intrusion events in the Wilkes Subglacial Basin with Pan-African ages (700 - 551 Ma) and Ross ages (550 - 450 Ma).

The Transantarctic Mountains (TAM) separate the warmer lithosphere of the West Antarctic rift system and the colder East Antarctic craton. Low velocity zones beneath the TAM imaged in recent seismological studies have been interpreted as warm low-density mantle material, suggesting a strong contribution of thermal support to the uplift of the TAM. We present new Curie Depth Point (CDP) and geothermal heat flow (GHF) maps of the northern TAM and adjacent Wilkes Subglacial Basin (WSB) based on high resolution magnetic airborne measurements. We find shallow CDP and high GHF, beneath the northern TAM reinforcing the idea of thermal support of the topography of the mountain range. Additionally, locally high GHF is observed in the Central Basin of the WSB and the Rennick Graben, which has not been resolved previously, while the broader WSB show lower GHF. Across the study area the GHF values range from 30 to 110 mW/m2. Lastly, we compare our CDP estimates to recent Moho depth estimates and our GHF estimates to sparse in situ GHF measurements as well as to existing continent-wide GHF estimates, which shows closed agreement to previous seismic estimates.

The UK Polar Data Centre (PDC, https://www.bas.ac.uk/data/uk-pdc/) is the focal point for Antarctic environmental data management in the UK. Part of the Natural Environmental Research Council’s (NERC) network of environmental data centres and based at the British Antarctic Survey (BAS), the PDC coordinates the management of polar data from UK-funded research. In the last two years, the geophysics team at the PDC has made significant progress to improve the management of BAS aerogeophysics data, a challenging task considering that the British Antarctic Survey is one of the largest acquisitors of airborne geophysics data over Antarctica. In 2020, we published bedrock elevation data for fourteen airborne radar surveys over the continent, and more than thirty airborne gravity and magnetics datasets. This year, we will release large swaths of processed airborne radar data collected by BAS since the early 2000s, including extensive surveys over Pine Island (2004-05) and Thwaites (2018-20) glaciers, as well as the large surveys covering the Wilkes subglacial basin (2005-06) and the South Pole (2015-16), amongst others. Considerable effort has been made to curate these datasets to make them up-to-date and comply with the FAIR (Findable, Accessible, Interoperable and Re-usable) principles. In doing so, we believe that these datasets will be a valuable asset to future geophysical and glaciological studies over the Antarctic. Our aim here is to show our progress in re-processing and publishing these datasets and, for the first time, showcase our new Polar Aerogeophysics Data Portal which will serve as a user-friendly interface to discover and download the newly-published aerogeophysics data deposited on BAS’s data catalogue.