Antarctica is not just ice

A new geological dataset of Antarctica has compiled legacy knowledge to depict ‘known geology’ of rock exposures rather than interpreted sub-ice features. GeoMAP will be particularly useful for continent-wide perspectives and cross-discipline interrogation.
Published in Earth & Environment
Antarctica is not just ice
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Despite Antarctica’s reputation as an icy expanse, there are over 52,000 km2 of exposed rocky areas that make up the mountains and exposed surfaces of the continent. Each of these areas contains important information on the continent’s geological, geomorphological, and glaciological history. Put simply, these rocks play an important role in - and tell us a lot about - the complex interaction of land, ice, atmosphere, and climate. Geological knowledge of the continent’s mountains, sediments and soils, helps pinpoint the location, history and movement of glaciers, and even meltwater production. These insights provide foundational knowledge for researchers, from climate scientists, to biologists, to ecologists and volcanologists.  Therefore, having an accurate digital record of the continent’s known surface geology is invaluable to researchers.

By late last century there were numerous hard-copy, regional-scale geological maps over different parts of Antarctica. Many had been scanned, some had been georeferenced, but few were more than raster digital information with an adjacent legend.  These legacy maps are reliable for defining bedrock geology (‘deep time’) and construction of the continent but have poor spatial reliability in the context of modern science located by global positioning system (GPS) and other satellite sensors. Also, the existing maps rarely contain full representation of glacial geology and cover sequences that hold information on the waxing and waning of Antarctica’s ice sheets.

Fig 1 There are many hard-copy, regional-scale geological maps over different parts of Antarctica, but the recent-release of a continent-wide dataset is expected to be a game changer for geological and cross-discipline science. Simon Cox (Project Lead) in the throes of the issue.

Other disciplines were also lacking a comprehensive representation of Antarctica's geosphere to examine how rock substrate influences biology and ecology, local climate and melting, the behaviour of ice, and the response of the continent to removal of ice.  For example, the piles of gravel left behind from waxing and waning ice sheets provide constraints on Antarctica’s glacial dynamics. The composition and colour of exposed rocky outcrops affect ice melt patterns. And underneath the ice in the Earth’s crust, different types of rocks emit heat which may contribute to the melting of ice. Foundational data for understanding the continent’s role in global climate and sea level rise, and the effects of climate change on the continent itself, may have been locally available but a continental-wide synthesis was sorely missing.

Seeking to rectify the situation, an ambitious project to build a high-quality, digital, geological dataset covering the entire Antarctic continent was first proposed in 2014. The Scientific Committee on Antarctic research (SCAR) supported the idea through formation of an Action Group. Construction of GeoMAP then became a large, and long-term, international effort led out of New Zealand by GNS Science in New Zealand, involving principal collaborators from USA, Norway, Italy, UK, Australia, and Russia, but with contributions from at least 14 nations.  Many others provided advice, data and support.

Building on the long legacy of Antarctic geological mapping, the GeoMAP team weaved original observations from heroic age Antarctica expeditions with today’s modern datasets. The scientists mined and collated all existing geological data across a range of sources, and harmonized interpretations into a systematic classification scheme using the international Geoscience Markup Language (GeoSciML) data protocols.  Much manual work was completed in the GNS Science office in Dunedin by a succession of student volunteers, “the Engine room”, who visited New Zealand on internships or worked remotely by videoconferencing in return for GIS-training and professional development. Students presented the results of their local mapping in conference abstracts, talks and posters as the dataset progressively evolved and improved. Their tasks included interpreting information from beautiful 20th Century hand-drawn maps, digitising hard-copy regional maps, relocating and integrating them with modern high-resolution imagery and datasets. All are now co-authors of the GeoMAP dataset and paper.

Fig 2 Much of the manual work capturing data was completed by an ‘engine room’ of student volunteers, who were supervised by Belinda Smith Lyttle (Lead data architect).

Many nations contributed maps from their previous geological surveys that were summarised into GeoMAP, and a strong imperative for the project was to ensure that all original work can be found and referenced easily within the database. Local experts across the globe then rigorously checked and reviewed data. As the dataset came together, the philosophy ‘the whole is greater than the sum of its parts’ began to ring true for geological knowledge of Antarctica through GeoMAP.  There are bibliographic links to 589 source maps and scientific literature within the data.

Now published, GeoMAP is the world’s first open-access resource that collates all the historical and existing geological data of Antarctica. It provides a detailed geological account of what we know about the frozen continent, all in one place.  The dataset should enable a new and diverse set of research questions to be explored, such as: How do rock outcrops affect ice sheet albedo and influence melting? How does geology influence water, minerals and energy availability to sustain biota?  Do particular rock outcrops serve as refugia for at-risk or invasive species? 

Fig 3 GeoMAP is rich with historical knowledge. Data layers across the continent show different facets of information, from rock type, rock age, meltwater patterns and links to original publications and maps where the information was derived from.

For geologists, GeoMAP provides an unprecedented level of detail about the continent's geology. A total of 99,080 polygons have been unified for depicting geology at 1:250,000 scale, but locally there are some areas with higher spatial resolution. Each rock or sediment locality has data about unit type, name, age, lithology, stratigraphy, previous work and supporting background information. Geological unit definition is based on both rock age and composition, providing a mixed chronostratigraphic- and lithostratigraphic-based classification. There are 186 distinct units for geological work, but some simplified classifications (into 21 or 8 classes) are likely to be more- widely useful for cross-discipline work.  GeoMAP v.2022-08 dataset is now freely available to download (https://doi.org/10.1594/PANGAEA.951482). The paper just published in Nature Scientific Data (https://doi.org/10.1038/s41597-023-02152-9) provides a handbook for its use and highlights the global importance of this dataset.

The GeoMAP team are extremely proud of the legacy they have created. Antarctica is much more than just ice, but although most people realise it is a major continental landmass, it can often be difficult to see and reconcile the complexity of interactions between rock, ice, water and air.  By mining geological observations, a rich new dataset has saved a large body of knowledge from impending obscurity.  It will be exciting to now watch it inform both geological and cross-discipline science, particularly in the new era of high-resolution satellite time series and artificial intelligence.

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