Holocene Deposits of the Southeastern Coast of the Gorlo Strait (White Sea): New Data of Diatom and Radiocarbon Analyses

Doklady Earth Sciences - Diatom analysis and radiocarbon dating of the sedimentary cover of terraces on the southeastern coast of the Gorlo Strait (White Sea) were carried out for the first time....     

REMOTE SENSING IMAGERY AND ECOLOGICAL PROBLEMS OF COASTAL ZONES

Materials derived from aerial and space surveys provided the basis for compilation of a series of geomorphological, geological, morphostructural, and lithodynamic maps as well as a map showing sources of manmade pollution. A derivative map of geoecological regions based on these maps makes it possible to estimate qualitatively the ecological state of any coastal region. The Buor-Khaya Gulf of the Laptev Sea is used as a test case. Translated by Edward Torrey, Alexandria, VA 22308 from: Geomorfologiya, 1995, No. 4, pp. 23-34.     

Dynamics of the ice cover and peculiarities of the ice transportation of the sediments at the tidal flats of the Kandalaksha Gulf of the White Sea

Ten years of semistationary studies of the interaction of the ice cover and the coastal relief of the Kandalakhsa Gulf in the White Sea allowed us to reveal the peculiarities of these processes in the warm and cold years and the mechanisms of the origination of ice forms, including ice tents, which govern the character of the tidal flats. Three dynamic fast ice zones are distinguished by their geomorphological location, morphology, and ice dynamics. The dependence of the mechanisms and volumes of the enrichment of the fast ice in the sediments on the coastal zone??s relief was established. At the coast of the Kindo Peninsula (Velikaya Salma Strait), the ice mostly contains fine-sandy sediments. Coarser sediments, including boulders, are occasional and frozen into the ice at the contact of the fast ice and the bottom. At the expense of the ice??s spreading by 4?C6 times in the warm years and 2?C4 times in the cold years, several thousand tons of sediments mostly from the tidal flat??s surface (100?C700 m³ from 1 km of coast in the wide tidal flats and <50 m³ on the steep coasts) are delivered to the water area.     

Identification of Icelandic tephras from the last two millennia in the White Sea region (Vodoprovodnoe peat bog,northwestern Russia)

The generation of reliable age models for palaeoenvironmental and archaeological records in the Eurasian Arctic is often problematic when using conventional dating techniques. Tephrochronology can potentially improve the chronologies of such records and synchronise disparate sedimentary archives. However, to date, systematic tephra studies are lacking for this region. This paper presents the first cryptotephra data from the White Sea region (northwestern Russia) based on a peat core spanning the past ~1800 years. We identify seven geochemical glass populations that derive from six Icelandic volcanoes and correlate four of them to north European tephra isochrons; these include Askja ad 1875, the basaltic component of the ad 877 Landnám tephra, and tephras BTD-15 (c. ad 1750–1650) and SL-2/SB-2 (ad 803–767) from unknown eruptions of Katla and Snæfellsjökull, respectively. The remaining three populations originate from Grímsvötn, Hekla and Katla; however, their attribution to individual eruptions remains ambiguous. These findings highlight the potential to extend the Late Holocene tephrochronological framework of northern Europe to the west Eurasian Arctic. The detection of at least three basaltic tephras in the core suggests that basaltic shards can be transported over larger distances than previously known and that peatlands are well suited to preserve such components.     

The distribution and utility of sea‐level indicators in Eurasian sub‐Arctic salt marshes (White Sea,Russia)

In support of efforts to reconstruct relative sea level (RSL), we investigated the utility of foraminifera, diatoms and bulk‐sediment geochemistry (δ¹³C, C:N and parameters measured by Rock‐Eval pyrolysis) as sea‐level indicators in Eurasian sub‐Arctic salt marshes. At three salt marshes (<15 km apart) in Dvina Bay (White Sea, Russia), we collected surface sediment samples along transects from subtidal to Taiga forest environments. Foraminifera at all sites formed bipartite assemblages, where elevations below mean high higher water (MHHW) were dominated by Miliammina spp. and elevations between MHHW and the highest occurrence of foraminifera were dominated by Jadammina macrescens and Balticammina pseudomacrescens. Five high‐diversity groups of diatoms were identified and they displayed pronounced variability amongst the study sites. Bulk‐sediment geochemistry recognized two groups (clastic‐dominated environments below MHHW and organic‐rich environments above MHHW). As one group included subtidal elevations and the other included supratidal elevations, we conclude that the measured geochemical parameters are not stand‐alone sea‐level indicators. Core JT2012 captured a regressive sediment succession of clastic, tidal‐flat sediment overlain by salt‐marsh organic silt and freshwater peat. The salt‐marsh sediment accumulated at 2804±52 years before present and preserved foraminifera (Jadammina macrescens and Balticammina pseudomacrescens) with good analogy to modern assemblages indicating that RSL was +2.60±0.47 m at this time. Diatoms confirm that marine influence decreased through time, but the lack of analogy between modern and core assemblages limited their utility as sea‐level indicators. Geochemical parameters also indicate a reduction in marine influence through time. We conclude that RSL reconstructions derived from salt‐marsh sediment preserved beneath Eurasian sub‐Arctic peatlands can provide valuable insight into the spatio‐temporal evolution of the Fennoscandian and Eurasian ice sheets.     

The role of neotectonics in the present day dynamics of the sea coastal zone in the western arctic continental platform areas

Cartographic neotectonic models have been created for the key areas of the coastal sea zone (CSZ) in the Western Arctic. These areas were identified within platforms of different ages. The neotectonics predetermines the most durable component of the CSZ, i.e., a wireframe with a fault block structure, and is one of the principal factors governing its development. In particular, it manifests itself in the difference between the exodynamics of parts of the CSZ, with their morpholithodynamic boundaries being similar to the structural aspect, their lithology being close, and the exposition to sea waves being the same. In predicting the development of the CSZ in the 21st century, one can say that there is a reason for some concern, but not for panic. The results of the investigations performed will assist in developing a more effective concept of shoreline protection and solving other applied and scientific problems associated with the junction zone between land and sea.