Cold–temperate transition surface and permafrost base (CTS-PB) as an environmental axis in glacier–permafrost relationship, based on research carried out on the Storglaciären and its forefield, northern Sweden

Abstract

Here, we present empirical ground penetrating radar (GPR) and electroresistivity tomography data (ERT) to verify the cold-temperate transition surface-permafrost base (CTS-PB) axis theoretical model. The data were collected from Storglaciären, in Tarfala, Northern Sweden, and its forefield. The GPR results show a material relation between the glacial ice and the sediments incorporated in the glacier, and a geophysical relation between the “cold ice” and the “temperate ice” layers. Clearly identifying lateral glacier margins is difficult, as periglacial and glacial environments frequently overlap. In this case, we identified areas showing permafrost aggradation already under the glacier, particularly where the CTS is replaced by the PB surface. This structure appears as a result of the influence of a cold climate over both the glacial and periglacial environments. The results show how these surfaces form a specific continuous environmental axis; thus, both glacial and periglacial areas can be treated uniformly as a specific continuum in the geophysical sense. Similarly, other examples previously described also allow identifying a continuation of permafrost from the periglacial environment onto the glacial base. In addition, the ERT results show the presence of double-layered periglacial permafrost, possibly suggesting a past climatic fluctuation in the study area.

Pervasive cold ice within a temperate glacier – implications for glacier thermal regimes, sediment transport and foreland geomorphology

“…Weertman (1961) described debris entrainment occurring when the freezing isotherm passes downwards into the substrate and subsequent thickening of the basal layer by sequential addition of layers of new ice at the bed by freeze-on. This process was investigated further by Dobiński et al (2017) at Storglaciären, where the CTS connects with the base of the permafrost following the freezing isotherm underneath the glacier separating frozen and unfrozen subglacial strata. Thus, the CTS forms an environmental continuum with its equivalent boundary in the periglacial environment corresponding to the base of the permafrost (Dobiński et al, 2017).…”

“…This process was investigated further by Dobiński et al (2017) at Storglaciären, where the CTS connects with the base of the permafrost following the freezing isotherm underneath the glacier separating frozen and unfrozen subglacial strata. Thus, the CTS forms an environmental continuum with its equivalent boundary in the periglacial environment corresponding to the base of the permafrost (Dobiński et al, 2017). Etzelmüller and Hagen (2005) previously modelled a similar thermal regime at Midtdalsbreen, where the CTS at the glacier bed is linked to the base of the permafrost that extends down into the subglacial substrate below the glacier snout.…”

Deglaciation Rate of Selected Nunataks in Spitsbergen, Svalbard—Potential for Permafrost Expansion above the Glacial Environment

“…In extreme cases, this surface lowers to such extent that the entire glacier shifts from polythermal to cold. At this stage, the CTS surface becomes the permafrost base (PB) surface, as noted by Dobiński et al [12,13,68] and Etzelmüller and Hagen [69]: "from a purely thermal point of view at least, glacier ice at sub-pressure melting point temperatures would become a part of the permafrost environment, and thin glaciers in Arctic or high altitude regions with the border of mountain permafrost altitude well below the glacier terminus are often entirely cold-based". Dobiński [5] presents a similar classification.…”

“…The glacier-permafrost relationship is quite difficult to characterize, mainly due to their differing defining nature, while permafrost is a physical condition (temperature), glaciers are material feature (ice/moraine). Recent studies have focused on approximating the definition of both glacial and periglacial systems through identifying permafrost as a type of underground ice; however, opinions on the glacier-permafrost relationship front are still divided [12][13][14][15][16][17][18].…”

Cryosphere and Spatial Uniformitarianism: A New Rule for Earth and Planetary Sciences

“…This layer is analogous to the frozen layer in the glacial forefield traditionally identified to permafrost [21]. Therefore, in the same way we can distinguish theoretically and empirically glacial and periglacial permafrost [6,[22][23][24][25], both can only be seen as lithospheric components. So, due to the intellectual limitations to identify ice as a rock, it is often considered as a specific, different additional element [9], thus escaping from rigid classifications.…”