GRSG 35th Conference 2024 Abstract

Title: Satellite-based mapping of silica-rich rock for future cosmogenic nuclide exposure dating in unvisited areas of Antarctica

Author: Jonathan Adams

Organisation: Imperial College London

Cosmogenic nuclide exposure dating is an important technique for reconstructing the deglacial history of ice sheets. Many of the most applied cosmogenic nuclides are extracted from the mineral quartz, and so are dependent on recovery of felsic (silica-rich) rock samples for analysis. Polar fieldwork is subject to time constraints and considerable logistical challenges making efficient sample recovery critical to successful research efforts.

Remote sensing offers an effective way to map the geology of large areas prior to fieldwork, but previous spectral mapping of smaller felsic rock outcrops in Antarctica using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor has been constrained by ASTER’s spatial resolution. In this study, we assess the viability of multispectral remote sensing to distinguish felsic from mafic rock outcrops at visible-near infrared (VNIR) and shortwave infrared (SWIR) wavelengths using both the ASTER and very high-resolution Worldview-3 (WV-3) imagery.

A combination of spectral mapping and ground truth from spectral measurements of 17 lithologic samples from Mt Murphy identified four dominant rock types including, felsic granites and gneisses, and mafic basalt and fragmental hydrovolcanic rock, which we used as a basis for felsic-mafic differentiation. Supervised classification results indicate WV-3 performs well at differentiating felsic and mafic rock types and that ASTER while coarser, could also achieve satisfactory results, and could be used in concert with more targeted WV-3 image acquisitions. The study led to the production of a revised felsic-mafic geologic map, which improves on current geologic knowledge of Mount Murphy. Taken together, our results using WV-3 and ASTER datasets for felsic-mafic characterisation of remote rock outcrops indicate the potential of spectral mapping as a useful tool for preliminary reconnaissance when planning future cosmogenic nuclide sampling campaigns.