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EN
Studies on Baltic nodules have been undertaken since the1920s. In the 1970sand 1980s, the Polish Geological Institute - National Research Institute conducted researches on the bottom sediments of the Baltic Sea, which allowed identifying the regions of occurrence of Fe-Mn nodules in the southern part of the Baltic Sea (Mojski, 1989-1994). Nodules from the Polish Baltic Sea Zone are the least studied element of the marine environment. So far, there is a lack of information on environmental-geological conditions of formation and occurrence of nodules, their metal resources and deposit potential. The Fe-Mn nodules may be a valuable source of information on the contamination of the Baltic Sea water and bottom sediments. In cooperation between the Institute of Oceanography of the University ofGdañsk and the Polish Geological Institute-NRI, two research cruises were carried out in August and September 2020 on a 5 X 5 km testing ground in the Gotland-Gdańsk Threshold region. The seabed surface was profiled using multibeam echo sounders and a side-scan sonar. A hundred samples of Fe-Mn nodules, 25 samples of surface sediments associated with the nodules, and25 samples of clay rocks underlain by marine sediments were collected. The extensive documentary material will enable, for the first time, to estimate the nodule resources and determine the regularity of their occurrence.
EN
Research by the Polish Geological Survey has been carried out along the southern Baltic coastal zone over a distance of 38 km. The Baltic Sea is classified as non-tidal, and its southern coasts are built entirely of weakly lithified sedimentary rocks. These deposits form three main types of coast, namely cliffs, barriers and alluvial coasts (wetlands), with the research focusing on the first two. Methods including remote sensing, mapping (geological, hydrogeological), offshore survey (bathymetric and geophysical measurements), laboratory analyses and modelling revealed a number of natural hazards. These are, respectively: (1) permanently occurring hazards, causing material damage such as: landslides, coastal erosion and seabed erosion; (2) incidental hazards such as dune breakage and storm surge overflow and (3) hypothetical threats that may occur in the future, such as hydrogeohazards defined here as flooding resulting from groundwater level rise or more rarely, earthquake threats.
EN
The paper presents the results of the first OSL dating of glaciofluvial and ice-marginal lake sediments which occur between end moraines of the Słupsk Bank and the Polish coast. The sand and gravel of glaciofluvial deltas on the Słupsk Bank were deposited most likely during a period from 14.3 ±1.2 to 16.6 ±1.4 ka ago. The deposition of silty-sandy sediments of the ice-marginal lake is dated at 14.51 ±0.81 and 14.6 ±1.4 ka years. Likewise, dates ranging from 13.74 ±0.84 to 16.70 ±1.1 ka obtained from low sandy ridges, related to the southern range of the ice-marginal lake in the Gardno-Łeba Lowland, indicate the most likely timing of their deposition. It can be concluded that a short stop of the ice sheet on the Słupsk Bank took place approximately 15.2 ka ago, which could be correlated with the position of the ice sheet front in central Skåne and in northern Lithuania at that time. Older and younger results were also obtained, except the dates mentioned above. The older ages show little sunlight exposure of sediments during their deposition. The younger dates indicate a marine origin of the sediments and show that some parts of glaciofluvial sediments were redeposited and exposed to sunlight at a later stage, most probably when dead-ice blocks were melting.
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