Glaciers surge ‘shovels’ forefield moraines for geological surveys, example from northern Kaffiøyra, Svalbard

Abstract

It is estimated that the impact of global warming in polar regions manifests double as much as other geographical provinces around the world, and in Svalbard particularly, reaches 7 times of it. Clearly, the most observable impact of these changes considers thinning of an ice-cover and glaciers retreat, which is reported as a ‘glacier mass balance’. The glacier submarine moraines studies in Svalbard, indicate that the small ‘glaciation epoch’ ended around 1909. That means that for the last several decades we observe a continuous retreat of the glaciers. It is estimated that since 1960s there is an overall negative glacier mass balance around the whole archipelago of Svalbard and in present, the total mass loss varies between 5 and 10 Gt/year. Also, recent studies report that the glacier retreat rates increase yearly, where in some areas can reach even over 100 meters per year.Our filedwork in 2021 and 2022 in Kaffiøyra, western Svalbard, shows that the glaciers retreat exposes new vast areas that had never been studied before. Since the glaciers age are between 20,000-30,000 years old, we are able to map for the first time the tectonic setting of the newly exposed areas. A continues retreat of the Glacier Aavatsmark in northern Kaffiøyra exposes a contact between formations of the Paleogene and Neoproterozoic, which is a boundary of a tectonic Forlandsunded Graben and Caledonian basement (Hecla Hoek sucession) of the Eurekan orogeny. In here, newly exposed outcrops reveal highly deformed and sheared phyllite and schist formations which indicate large boundary of a transpression and following transtension phases of the deformation of the metamorphic complex characterized by metamorphic metasandstones, quartzites and serpentinites of the Neroproterozic, mainly- Late Cryogenian and Ediacaran. We also indicate clear strike-slip components along this boundary.However, in our study area we have found that a glacier surge greatly aids exposition of the new outcrops especially in the glacier forefield regions. The surge is an abnormal occurrence where an entire glacier suddenly accelerates its movement up to several meters per day. It is associated with a disbalance of a glacier mass at the ablation zone versus accumulation zone. A continuous reduction of a glacier mass at an ablation and increase of sub-glacier waters can trigger a ‘glacier surge’, where velocity can reach up to 1000 times comparing to quiescent time and can last from months to years. In 2013 a massive surge of a glacier Aavatsmark yielded glacier movement up to 5 meters per day and lasted for two years. Because of this sudden increase of the ice mass movement the front of the glacier toe (terminus) served as a ‘shovelling tool’ for the moraines in the forefield areas. This unusual occurrence cleaned vast areas of new outcrops of the boundary of the Forlandsunded Graben that have never been mapped before. With the support by UAV 3D mapping along the graben boundary, we have put new tectonic features as well as structural measurements of the area.