Pingo development in Grøndalen, West Spitsbergen

Abstract

Pingos are common features in permafrost regions that form by subsurface massive-ice aggradation and create hill-like landforms. Pingos on Spitsbergen have been previously studied to explore their structure, formation timing, connection to springs as well as their role in post-glacial landform evolution. However, detailed hydrochemical and stable-15 isotope studies of massive ice samples recovered by drilling has yet to be used to study the origin and freezing conditions in pingos. Our core record of 20.7 m thick massive pingo ice from Grøndalen differentiates into four units: two characterised by decreasing δ 18 O and δD and increasing d (units I and III), and two others show the opposite trend (units II and IV). These delineate changes between episodes of closed-system freezing with only slight recharge inversions of the water reservoir, and more complicated episodes of groundwater freezing under semi-closed conditions when the reservoir got recharged. The 20water source for pingo formation shows similarity to spring water data from the valley with prevalent Na + and HCO3ions.The sub-permafrost groundwater originates from subglacial meltwater that most probably followed the fault structures of Grøndalen and Bøhmdalen. Today the pingo of Grøndalen is relict and degrading due to warming surface temperatures. The state of pingos on Spitsbergen depends on complex interaction of climate, permafrost and groundwater hydrology conditions, and is thus highly sensitive to climate warming. 25

Seismic and Electrical Geophysical Characterization of an Incipient Coastal Open‐System Pingo: Lagoon Pingo, Svalbard

“…In the coring of marine‐based pingos in Grøndalen, Demidov et al. (2019) demonstrate massive ice exceeding 20 m in thickness beneath a pingo of 9 m height. Whilst numerical simulations of palsas and lithalsas analogous to our proposed structure of Lagoon Pingo have demonstrated that segregation ice can produce ∼6 m of heave over a period of 150 years (An & Allard, 1995), further coring is necessary to validate the precise architecture of frozen ground within these pingos.…”

“…Liestøl, 1977) and, (c) those occurring in nearshore or low‐lying environments, undergoing glacio‐isostatic uplift. Despite this categorization of their hydraulic properties, the mechanism and processes which govern pingo formation still remain poorly understood (Demidov et al., 2019; Gurney, 1998; Kunz & Kneisel, 2021), and studies assessing early pingo forms remain limited.…”

Integrated Geophysical Investigations of a Methane Releasing Pingo in a Changing Permafrost Environment, Svalbard

“…The fine-grained Holocene muds and clays are frost-susceptible, and arguably more conducive to the formation of segregation ice (Smith, 1985). This dependence of sedimentary context is perhaps best highlighted in cores of pingos below the Holocene marine limit in Grøndalen, Svalbard (Demidov et al, 2019). Within these, massive ice is confined exclusively within assemblages of non-marine gravelly sands and loams.…”

“…Yet despite a recent appreciation for their role as a conduit of methane through continuous permafrost, open-system pingos are poorly understood (e.g. Gurney, 1998;Demidov et al, 2019;Kunz and Kneisel, 2021). Firstly, uncertainty remains regarding their structural composition.…”

“…Liestøl, 1977) and, (iii) those occurring in nearshore or low-lying environments, undergoing glacio-isostatic uplift. Despite this categorization of their hydraulic properties, the mechanism and processes which govern pingo formation still remain poorly understood Demidov et al, 2019;Kunz and Kneisel, 2021), and studies assessing early pingo forms remain limited.…”