Reconstruction of late Quaternary sedimentary environments at the southern Mendeleev Ridge (Arctic Ocean)

The late Pleistocene history of the Arctic comprised cyclical changes in the extension of land-based ice sheets and sea-ice cover that affected sedimentary environments in the Arctic Ocean. This PhD thesis focuses on sediment records from the Mendeleev Ridge spanning the last 200 ka. Over this time period, variable sedimentation patterns were described and possible implications for reconstruction of glacial/interglacial paleoenvironments were provided. One of the main goals of this study was to identify mineralogical and inorganic-geochemical tracers in marine sediments that could be used for discrimination of sediment provenance and consequently for reconstruction of sediment pathways

The International Bathymetric Chart of the Southern Ocean Version 2 (IBCSO v2)

The Southern Ocean surrounding Antarctica is a region that is key to a range of climatic and oceanographic processes with worldwide effects, and is characterised by high biological productivity and biodiversity. Since 2013, the International Bathymetric Chart of the Southern Ocean (IBCSO) has represented the most comprehensive compilation of bathymetry for the Southern Ocean south of 60°S. Recently, the IBCSO Project has combined its efforts with the Nippon Foundation – GEBCO Seabed 2030 Project supporting the goal of mapping the world’s oceans by 2030. New datasets initiated a second version of IBCSO (IBCSO v2). This version extends to 50°S (covering approximately 2.4 times the area of seafloor of the previous version) including the gateways of the Antarctic Circumpolar Current and the Antarctic circumpolar frontal systems. Due to increased (multibeam) data coverage, IBCSO v2 significantly improves the overall representation of the Southern Ocean seafloor and resolves many submarine landforms in more detail. This makes IBCSO v2 the most authoritative seafloor map of the area south of 50°S

Rekonstruktion der spätquartären Sedimentationsprozesse in der Umgebung des Mendeleew-Rückens (Arktischer Ozean)

The late Pleistocene history of the Arctic comprised cyclical changes in the extension of land-based ice sheets and sea-ice cover that affected sedimentary environments in the Arctic Ocean. This PhD thesis focuses on sediment records from the Mendeleev Ridge spanning the last 200 ka. Over this time period, variable sedimentation patterns were described and possible implications for reconstruction of glacial/interglacial paleoenvironments were provided. One of the main goals of this study was to identify mineralogical and inorganic-geochemical tracers in marine sediments that could be used for discrimination of sediment provenance and consequently for reconstruction of sediment pathways

Late Quaternary Glacial/Interglacial Regimes at the East Siberian Sea Continental Margin : Reconstructions Based on a Sedimentary Record from Southern Mendeleev Ridge

This study is focused on sediment cores PS72/344-1 (boxcorer) and PS72/344-3 (kastenlot) recovered from the western flank of the Southern Mendeleev Ridge during the ARKXXIII/3 (Arctic-2008) Expedition of RV ‘Polarstern’. The composite core PS 72/344 represents an undisturbed sedimentary sequence with the length of 8 m, scanned onboard for physical properties and then sampled at every 10 cm. In the present research we use various sedimentary proxies such as lithology (sediment colour and ice-rafted debris contents), physical properties (density, magnetic susceptibility, p-wave velocity, shear strength measurements), mineralogy (bulk mineralogical composition), geochemistry (total organic carbon contents, C/N ratio) and biostratigraphy (distribution of planktonic and benthic foraminifers) to reconstruct paleoceonographical conditions in the Siberian part of the Amerasian Basin during the Late Quaternary times. The age model for core PS72/344 is constrained by correlation to the stratigraphy developed for the Mendeleev Ridge (Polyak et al., 2004; Adler et al., 2009). For correlation we mainly used lithology (color cycles, IRD contents) and detrital carbonate (dolomite) contents as well as distribution of forams. According to the proposed tratigraphical framework, the PS72/344 record comprises marine isotope stages (MIS) 5 to 1. The PS72/344 proxy record demonstrates that sedimentary environments at the East Siberian Sea continental margin were strongly variable during late Quaternary times. Sedimentation patterns show that based on the proxy data we can suggest that there were three major scenarios of transportation and deposition of terrigenous material derived from the adjacent shelves, generally controlled by the extension of sea-ice cover and iceberg discharge. Using this framework of general paleoenvironmental scenarios in the studied area, we discuss the variable paleoceanographic regimes in the Arctic Ocean related to the history of glaciations in Northern Euarasia and North America during late Quaternary times (MIS 5 to present) using published data on sediment cores from the Arctic Basin. Severe ice conditions in the Arctic Ocean consistent with onsets of land-based glaciations in Northern Eurasia and North America were reconstructed for early and mid MIS 5 (two glacial/interglacial cycles), substage 5a, the MIS 5a/4 transition and MIS 2. Enhanced deposition of ice-rafted debris took place in early MIS 5, during the MIS 5a/5 transition, in MIS 4, late MIS 3. Interglacial periods correspond to MIS 5 (not enough dating points), the transitions MIS 5/5a, MIS 5a/4, MIS 3/2. The proposed age model is still preliminary that limits the paleonvironmental reconstructions and more data should be obtained during further studies