Brief communication: Increased glacier mass loss in the Russian High Arctic (2010–2017)

Glaciers in the Russian High Arctic have been subject to extensive atmospheric warming due to global climate change, yet their contribution to sea level rise has been relatively small over the past decades. Here we show surface elevation change measurements and geodetic mass balances of 93 % of all glacierized areas of Novaya Zemlya, Severnaya Zemlya, and Franz Josef Land using interferometric synthetic aperture radar measurements taken between 2010 and 2017. We calculate an overall mass loss rate of -22±6 Gt a−1, corresponding to a sea level rise contribution of 0.06±0.02 mm a−1. Compared to measurements prior to 2010, mass loss of glaciers on the Russian archipelagos has doubled in recent years.

The Yenisei-Khatanga Composite Tectono-Sedimentary Element, Northern Siberia

The Yenisei-Khatanga Composite Tectono-Sedimentary Element (YKh CTSE) is located between the Siberian Craton and the Taimyr-Severnaya Zemlya fold-and-thrust belt. The total thickness of the Mesoproterozoic-Cenozoic sediments of YKh CTSE reaches 20 to 25 km. They are divided into four tectono-sedimentary elements (TSE): (i) Mesoproterozoic-early Carboniferous Siberian Craton continental margin, (ii) middle Carboniferous-Middle Triassic syn-orogenic Taimyr foreland basin, (iii) late Permian-Early Triassic syn-rift, and (iv) Triassic-Early Paleocene post-rift. The last one is the most important in terms of its petroleum potential and is the most drilled part of the CTSE. Its thickness accounts for half of the total thickness of YKh CTSE. The margins of the post-rift TSE and the inner system of inversion swells and adjacent troughs and depressions were shaped by three tectonic events: (i) middle Carboniferous-Middle Triassic Taimyr orogeny, (ii) Late Jurassic-Early Cretaceous Verkhoyansk orogeny, (iii) Late Cenozoic uplift. These processes led to more intense migration of hydrocarbons, the trap formation and their infill with hydrocarbons. Triassic, Jurassic, and Lower Cretaceous source rocks are mostly gas-prone, and among 20 discovered fields in Jurassic and Cretaceous plays, 17 are gas or mixed-type fields.

Notes on the fishes of the Severnaya Zemlya archipelago and the spawning area of polar cod Boreogadus saida (Gadidae)

Data on the fishes of the high-latitude Severnaya Zemlya archipelago (the North Land) is presented. The archipelago is located in the Arctic on the border between the Kara Sea and the Laptev Sea. The ichthyofauna of the archipelago has not been studied; therefore, even small collections are of interest. Fish samples were obtained during the expedition “Open Ocean: Arctic Archipelagos – 2019: Severnaya Zemlya”. In addition, the samples from this area in the collections of the Zoological Institute (ZIN) were studied, which have been received from polar expeditions to the Kara and Laptev seas during the entire era of polar research. The most significant fact is the discovery of mass accumulation of polar cod Boreogadus saida (Lepechin, 1774) larvae in Mikoyan Bay (Bolshevik Island), which gives evidence of important spawning grounds near Severnaya Zemlya. Indirect evidence of this can be found in the publications of polar explorers who overwintered on Severnaya Zemlya in the 1930s–1950s and have reported that the polar cod approaches the shores for spawning in August, in huge schools. The waters of Severnaya Zemlya represent the spawning area of polar cod in the central part of the Eurasian shelf, which is not mentioned in current literature. In addition to polar cod, a few more species are registered in samples from the coastal waters of the archipelago (depths to 38 m), rough hookear sculpin Artediellus scaber Knipowitsch, 1907, twohorn sculpin Icelus bicornis (Reinhardt, 1840) (family Cottidae), Liparis tunicatus Reinhardt, 1836, black-bellied snailfish L. cf. fabricii (Liparidae), Knipowich eelpout Gymnelus knipowitschi Chernova, 1999 (Zoarcidae) and three-spined stickleback Gasterosteus aculeatus (Linnaeus, 1758) (Gasterosteidae). In the deepwater straits, snailfish Careproctus sp. (174–234 m) and pale eelpout Lycodes pallidus Collett, 1879 (105–348 m) were found. The Arctic charr Salvelinus alpinus (Linnaeus, 1758) (Salmonidae) inhabits some lakes of the archipelago. This is the first finding of a three-spined stickleback in the east of the Kara Sea.

The nature of regional magnetic anomalies in the northeast of the Barents-Kara continental margin based on the results of seismic data interpretation

Based on the interpretation of seismic sections via seismic reflection method, the lines of which intersect the positive magnetic anomalies in the St. Anna Trough and on the North Kara Shelf, the authors have substantiated the position of the Early Cretaceous dike belt in the north of the Barents-Kara platform for the first time. They traced the belt from the arch-block elevation of arch. Franz Josef Land, which belongs to the Svalbard platе through the Saint Anna Trough and further into the Kara platе to arch. Severnaya Zemlya. The distinguished dyke belt has discordant relationships with the structural-tectonic plan of the region under consideration. The authors illustrate the manifestations of dyke magmatism in the marked tectonic elements in seismic sections, and conclude that the dyke belt relates to the formation of the structural system of the Arctic basin.

COSMO-CLM Russian Arctic hindcast 1980 – 2016: experimental design and first evaluation results

<p>Detailed long-term hydrometeorological dataset for Russian Arctic seas was created using hydrodynamic modelling via regional nonhydrostatic atmospheric model COSMO-CLM for 1980 – 2016 period with ~12 km grid. Many test experiments with different model options for summertime and wintertime periods were evaluated to determine the best model configuration. Verification has showed that optimal model setup included usage of ERA-Interim reanalysis as forcing data, new model version 5.05 with a so-called ICON-based physics and spectral nudging technique. Final long-term experiments were simulated on the MSU Supercomputer Complex “Lomonosov-2” become more than 120 Tb data volume excluding many side files.</p><p>Primary evaluation of obtained dataset was done for surface wind and temperature variables. There are some mesoscale details in wind sped climatology reproduced by COSMO-CLM dataset including the Svalbard, Severnaya Zemlya islands, and the western coast of the Novaya Zemlya island. At the same time, high wind speed frequencies based on COSMO-CLM data increased compared to ERA-Interim, especially over Barents Sea, Arctic islands (Novaya Zemlya) and some seacoasts and mainland areas. Regional details are manifested in wind speed increase and marked well for large lakes and orography (Taymyr and Kola peninsulas, Eastern Siberia highlands).</p><p>Comparison of two periods (1980 ­­– 1990 and 2010 – 2016) has shown that spatial distributions of high wind speed frequencies are very similar, but there are some detailed differences. Wind speed frequencies above 20.8 m/s has been decreased in the last decade over the Novaya Zemlya, southwest from Svalbard, middle Siberia inlands; however, it has been increased over Franz Josef Land and Severnaya Zemlya.</p><p>Large-scale temperature climatology patterns have shown a good accordance between ERA-Interim and COSMO-CLM datasets. Significant temperature patterns are detailed relief and lakes manifestations, e.g., over Scandinavian mountains, Eastern Siberian and Taymyr highlands, Novaya Zemlya ranges. The added value in the 1% temperature percentile patterns is more pronounced, especially in the mountainous Eastern Siberia. Regional features are prominent over Onega and Ladoga lakes, and western Kara Sea. There is a remarkable warming over islands and Eastern Siberia valleys, and more clear temperature differentiation between ridges and valleys.</p><p>The nearest prospect of the COSMO-CLM Russian Arctic dataset application is its comparison with other appropriate datasets including reanalyses, satellite data, observations, etc. This will provide important and useful information about opportunities and restrictions of this dataset regarding different variables and specific regions, outline the limits of its applicability and get framework of possible tasks. The other important task is to share this dataset with scientific community.</p>

Carboniferous granitic plutons of Nordensheld Archipelago (eastern part of the Kara Sea, Russian High Arctic)

<p>Nordensheld Archipelago is a relatively large cluster of islands in the eastern part of the Kara Sea located north of the Taymyr Peninsula. Belonging to the Northern Taimyr tectonic domain of the Taimyr-Severnaya Zemlya fold-and-thrust belt, this area in Late Paleozoic represented southern part of the Kara Terrane.</p><p>Samples were collected from outcrops across the Nordensheld Archipelago and shallow offshore wells in the close proximity to the archipelago and from offshore well located in Toll bay (eastern part of the Kara sea). Studied plutons are represented by coarse- to medium-grained biotite, two mica and hornblende-biotite granites. U-Pb dating of the granites yelled ages of ca. 334 and 326 Ma. The granitoids are high- to medium acidic, mainly calc-alkalic to alkali-calcic, ferroan and magnesian, metalumious and peraluminous.</p><p>The U-Pb zircon age from the Toll Bay well is the first granite age obtained offshore within eastern part of the Kara Sea. Petrographic and geochemical features of the Nordensheld Archipelago and eastern Kara Sea Visean-Serpukhovian granites indicate their suprasubduction origin. This correlates well with data from Northern Taimyr and provides new evidence for the Uralian Ocean subduction magmatism within Taimyr-Severnaya Zemlya fold-and-thrust belt.</p><p>This research was supported by RFBR grant № 19-35-90006, Russian Science Foundation grant № 20-17-00169.</p>

Low-Magnitude Earthquakes at the Eastern Ultraslow-Spreading Gakkel Ridge, Arctic Ocean

Thanks to the new permanent seismic stations installed in the Franz Joseph Land and Severnaya Zemlya arctic archipelagoes, it has become possible at present to record earthquakes occurring in the eastern Gakkel ridge with a much lower detection threshold than that provided by the global network. At present, the lowest recorded magnitude is ML 2.4 and the magnitude of completeness is 3.4. We examined the results of seismic monitoring conducted from December 2016 through January 2020 to show that the earthquake epicenters are not uniformly distributed both in space and over time within the eastern part of the ridge. There were periods of quiescence and seismic activity. Most of the epicenters are confined to the area between 86° and 95.0° E. Relative location techniques were used to locate the single major swarm of earthquakes recorded so far. Most earthquakes were recorded by two or three stations only, so that relative location techniques have been able to yield reliable data for an analysis of the swarm. We showed that there have been actually two swarms that contained different numbers of events. The earthquakes in the larger swarm were occurring nonuniformly over time and clustered at certain depths. The ML scale was calibrated for the Eurasian Arctic based on records of the seismic stations installed in the Svalbard Archipelago, Franz Joseph Land, and on Severnaya Zemlya: −logA0(R)=1.5×logR100+1.0×10−4(R−100)+3.0. The results will help expand our knowledge of the tectonic and magmatic processes occurring within the ultraslow Gakkel ridge, which are reflected in the local seismicity.

ON THE POROSITY OF THE UNCONSOLIDATED PART OF ICE RIDGE KEEL

The paper discusses the distribution of porosity of the unconsolidated part of the keel of ten first-year ice ridges investigated in the central Arctic basin and the Shokalsky Strait (Severnaya Zemlya) in 2012–2019. These studies were performed using thermal drilling with the computer (logger) recording of penetration rate. Boreholes were drilled along the cross-section of the ridge crest, mainly at 0.25-m intervals. The porosity values for the unconsolidated part of the keel are presented on the diagram as a point cloud. The horizontal position of the points is determined by the relative distance between the borehole and the point where the keel has the maximum draft. As moving away from this point, the average porosity of the unconsolidated part of the keel tends to increase. This feature is a consequence of the Archimedes force effect and agrees with the model of porosity changes from the theory of granular media.