Geocryological and Hydrogeological Conditions of the Western Part of Nordenskiold Land (Spitsbergen Archipelago)

Abstract

This work summarizes the archived data of geocryological and hydrogeological conditions in the west of Nordenskiold Land on the Spitsbergen Archipelago. The historical data obtained in the Soviet period during coal exploration are reviewed together with the results of our own studies performed as part of the Russian Scientific Arctic Expedition on Spitsbergen (RAE-S) in 2016-2020. With respect to geocryology, the region is assigned to the zone of continuous permafrost. The thickness of rocks and sediments with temperatures below zero is about 100 m near the coast and increases to 540 m on watersheds. The mean annual ground temperature near the zero-amplitude depth varies from -3.6 to -2.2°C. Below this layer, the temperature curve in the top part of the section tends to deviate toward positive temperatures, reflecting the modern cycle of climate warming. From the hydrogeological point of view, the area belongs to the marginal zone of the West Spitsbergen cryoadartesian basin. Seawater intrusions near the coast form saline subpermafrost aquifers, including those with temperatures below zero, reflecting the seawater (sodium chloride) composition and hydraulic heads close to sea level. Fresh and slightly saline (sodium bicarbonate on the east coast of Grønfjorden and magnesium-calcium sulfate in gypsum-bearing deposits on the west coast) subpermafrost water with hydraulic heads reaching 100 m above sea level is fed by water-saturated ice in the deep layers of large glaciers.

Pingo drilling reveals sodium–chloride‐dominated massive ice in Grøndalen, Spitsbergen

“…It is characterized by low mineralization (usually 0.03-0.6 g/L) and variable composition, commonly dominated by Ca 2+ , Na + , Mg 2+ , SO 4 2À and HCO 3 À ions. 19 The second type is represented by subpermafrost aquifers located within fault and fissure zones in upper geological strata (Paleogene and Cretaceous rocks) of the Nordenskiöld Land Tertiary Basin. 19 Groundwater is characterized by relatively low mineralization ranging from 1 to 3.3 g/L (up to 12 g/L according to Kurkov and Neizvestnov 18 ), and is dominated by Na + and HCO 3 À ions.…”

“…19 The second type is represented by subpermafrost aquifers located within fault and fissure zones in upper geological strata (Paleogene and Cretaceous rocks) of the Nordenskiöld Land Tertiary Basin. 19 Groundwater is characterized by relatively low mineralization ranging from 1 to 3.3 g/L (up to 12 g/L according to Kurkov and Neizvestnov 18 ), and is dominated by Na + and HCO 3 À ions. These usually pressurized aquifers are encountered below permafrost and might be located both below and up to 100 m above the present sea level (asl).…”

“…They might recharge via groundwater moving in fissures and faults under warm-based glaciers, 19,20 by spring and summer precipitation filtering down from the surface through faults in the permafrost, 18,21 and by water filtering from large lakes in the upper valleys (such as Lake Istjørna) that have enough area and depth to facilitate the existence of permanent taliks beneath them. 19 Subglacial meltwater runoff feeding proglacial winter icings that are broadly spread on Spitsbergen can be classified as an intermediate between surface and subpermafrost aquifers. 22 The third type is represented by sub-and intrapermafrost highly mineralized aquifers (30-35 g/L and higher) dominated by Na + and Cl À groundwater that can be considered to be of marine origin.…”

“…Both sub-and intrapermafrost saline aquifers as well as level fluctuations following sea tides were registered in nearshore boreholes around Barentsburg. 20 Residual Holocene transgression marine cryopegs have been found within Grøndalen Valley floor sediments above present sea level 19 and could also occupy raised marine terraces. 18 Cretaceous-Paleogene saline aquifers are buried more than 400 m below the surface in midland regions of the Tertiary basin and are found at shallower depths near the sea at Grønfjorden, Grumantbyen, and elsewhere on the edges of the basin 18 following the dip of the geological strata.…”

“…This groundwater has a typical marine ion composition and mineralization (30-35 g/L), is pressurized at about sea level, and might be interconnected with the present-day sea via nearshore aquifers. 19,20 However, the last of these was disputed after Barentsburg mine water inflow decreased during 1949-1980 drainage and aquifer funnel depletion, 21 suggesting a stagnant regime of Cretaceous-Paleogene age groundwater. Relative positioning with sodium bicarbonate aquifers can be quite complex due to the nature of fault-dominated groundwater flow; the Nordenskiöld Land Tertiary Basin has been classified as cryoadartesian.…”