ALBERT

Description: 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 and connection to springs as well as their role in postglacial landform evolution. However, detailed hydrochemical and stable-isotope studies of massive-ice samples recovered by drilling have 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 is differentiated into four units: two characterised by decreasing δ18O and δD and increasing d (units I and III) and two others showing 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 was recharged. The water source for pingo formation shows similarity to spring water data from the valley with prevalent Na+ and HCO3- ions. The sub-permafrost groundwater originates from subglacial meltwater that most probably followed the fault structures of Grøndalen and Bøhmdalen. The presence of permafrost below the pingo ice body suggests that the talik is frozen, and the water supply and pingo growth are terminated. The maximum thaw depth of the active layer reaching the top of the massive ice leads to its successive melt with crater development and makes the pingo extremely sensitive to further warming.

Description: The permanently frozen volcanic sediment is one of the most promising geological objects for searching life on Mars. On Earth, volcanic intrusions into permafrost result in formation of the unique microbial communities. We propose several terrestrial analogues of Martian polar volcanoes, such as the permanently frozen volcanic sediments on the Kamchatka peninsula and in Antarctica. The present study shows applicability of the morphometric analysis for demonstration of the morphological similarity between the terrestrial and Martian cinder cones. In the present work, the morphometric analysis of young Martian landforms is based on the assumption that the conical structures identified on digital terrain model (DTM) are volcanic cinder cones. Morphometric analysis of the studied cones showed a range of degradation. The extent of degradation may be an indicator of age based on comparison with volcanic cinder cones on Earth. A morphometric analysis of potentially young volcanic cones in the North Polar Region of Mars was performed to estimate their relative age. The 14 potential cinder cones were identified using the DTM provided by Mars Express High Resolution Stereo Camera (HRSC), allowing for the basic morphometric calculations. The majority of the cinder cones are localized in the Chasma Boreale region within the area 79°–81°N and 261°–295°E. The calculated morphometric parameters showed that the cone average steepness varied from 3.4° to 11.8°, cone height-to-width ratio varied from 0.025 to 0.12, and the ratio between surface and basal area of the cone varied from 1.005 to 1.131. The studied cinder cones were classified with respect to the morphometric ratios assuming that larger values correspond to the younger structures. Employing the terrestrial analogy of morphometric ratios as a proxy for relative geological age, we suggest that existing microorganisms may be found in permafrost of young Martian cinder cones.

Description: 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-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 δ18O 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 water source for pingo formation shows similarity to spring water data from the valley with prevalent Na+ and HCO3- ions. 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.

Description: The drilling of the 10.5 m high Nori pingo that stands at 32 m asl in Grøndalen Valley (Spitsbergen) performed in April 2019 reached a depth of 21.8 m bs (core #13, starting from 42.5 m asl, 77.99483 °N, 14.59009 °E) and revealed 16.1 m thick massive ice. The core was obtained with a portable gasoline-powered rotary drilling rig (UKB 12/25, Vorovskiy Machine Factory, Ekaterinburg, Russia). The core pieces with diameter 112-76 mm were lifted for sampling to the surface every 30–50 cm. After documentation and cryolithological description core pieces were sealed in zip lock bags. Ice samples were split in two parts - one part for stable isotope analyses, another part for ion content measurement. They were kept frozen for transportation while sediment samples were kept unfrozen. Moisture content was analyzed in laboratory by measuring sediment samples weight before and after drying. The stable water isotope composition (δ18O and δD) of massive pingo ice was analyzed at the Climate and Environmental Research Laboratory (CERL, Arctic and Antarctic Research Institute, St. Petersburg, Russia) using a Picarro L2120- i analyzer. After every five samples the working standard (SPB-2, δ18O = -9.66 ‰ and δD = -74.1 ‰) was measured. SPB-2 is made of distilled St. Petersburg tap water and is calibrated against the International Atomic Energy Agency (IAEA) standards VSMOW-2 (Vienna Standard Mean Ocean Water 2), GISP (Greenland Ice Sheet Precipitation), and SLAP-2 (Standard Light Antarctic Precipitation 2). The reproducibility of the results is 0.08 ‰ for δ18O and 0.4 ‰ for δD and was assessed by re-measuring a random selection of 10% of the total samples. The measurement error is thus 1-2 orders of magnitude less than the natural isotopic variability of pingo ice, which is satisfactory for the purpose of this study. The δ18O and δD values are given as per mil (‰) difference to the VSMOW-2 standard. The deuterium excess (d) is calculated as d = δD - 8δ18O29. The ion content of sedimentary permafrost samples from core #13 was estimated after water extraction at the analytical laboratory of RAE-S, Barentsburg. The material was dried and sieved at 1 mm. About 20 g of the sediment were suspended in 100 ml of de-ionized water and filtered through 0.45 μm nylon mesh within 3 minutes after stirring. Electrical conductivity (EC, measured in μS cm-1) and pH values were estimated with a Mettler Toledo Seven Compact S 220. EC values were transformed automatically by the instrument into general ion content (mineralization) values given as mg L-1. Major anions and cations in the water extracts were analyzed by an ion chromatograph (Shimadzu LC-20 Prominence) equipped with the Shimadzu CDD-10AVvp conductometric detector and ion exchange columns for anions (Phenomenex Star-ion A300) and for cations (Shodex ICYS-50). Bicarbonate content was measured by a Shimadzu TOC-L analyzer via catalytic oxidizing at +680o C and subsequent infrared detecting. Melted pingo ice samples from core #13 and spring water samples were analyzed after filtration through 0.45 μm nylon mesh on the same equipment using the same techniques for pH, EC, and ion composition as for sedimentary permafrost samples. Analyses and research were aimed at determining major characteristics of the Nori pingo including its internal structure, groundwater source, and geochemical and isotopic stages of formation.

Description: Three permafrost cores including one pingo (core#9) were drilled in spring 2017 and 2018 in Grøndalen, West Spitsbergen near Barentsburg. The cores were analysed for major ions and stable water isotopes. From one of the borehole (borehole#9) ground temperature data were obtained on 12 September 2018.