Remote sensing and geologic mapping of glaciovolcanic deposits in the region surrounding Askja (Dyngjufjöll) volcano, Iceland

The surface geology of the Northern Volcanic Zone in Iceland is dominated by volcanic ridges, central volcanoes, shield volcanoes, and tuyas. The largest features are typically ice-confined (glaciovolcanic) in origin, and are overlain by voluminous Holocene (subaerial) lavas and glacial outwash deposits. The literature has focused heavily on prominent or very young features, neglecting small and older volcanic features. The purpose of this study is to demonstrate the application of remote-sensing mapping techniques to the glaciovolcanic environment in order to identify dominant lithologies and determine locations for textural, stratigraphic, and age studies. The deposits targeted in this study occur on and around Askja volcano, in central Iceland, including Pleistocene glaciovolcanic tuffs and subaerial pumice from the 1875 rhyolitic eruption of Askja. Data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) were used in conjunction with previously published geologic and remote-sensing data sets and recent field work on glaciovolcanic deposits of Askja for validation. Remotely acquired data sets include aerial photographs and one ASTER scene obtained in August 2010. Visible and near-infrared (VNIR) and thermal infrared (TIR) classifications and linear deconvolution of the TIR emissivity data were performed using end-members derived from regions of interest and laboratory spectra. End-members were selected from samples of representative lithologic units within the field area, including glaciovolcanic deposits (pillow lavas, tuffs, etc.), historical deposits (1875 pumice, 1920s basaltic lavas), and Holocene basaltic lavas from Askja. The results demonstrate the potential for remote sensing-based ground cover mapping of areas of glaciovolcanic deposits relevant to palaeo-ice reconstructions in areas such as Iceland, Antarctica, and British Columbia. Remote sensing-based mapping will benefit glaciovolcanic studies, by determining the lithologic variability of these relatively inaccessible massifs and serving as an important springboard for the identification of future field sites in remote areas.