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  • Other Sources  (2)
  • DEEP sediment succession  (1)
  • Geophysics  (1)
  • 1
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    The geodynamic and limnological evolution of Balkan Lake Ohrid, possibly the oldest extant lake in Europe (2022)
    Details
    Publication Date: 2023-12-04
    Description: Studies of the upper 447 m of the DEEP site sediment succession from central Lake Ohrid, Balkan Peninsula, North Macedonia and Albania provided important insights into the regional climate history and evolutionary dynamics since permanent lacustrine conditions established at 1.36 million years ago (Ma). This paper focuses on the entire 584‐m‐long DEEP sediment succession and a comparison to a 197‐m‐long sediment succession from the Pestani site ~5 km to the east in the lake, where drilling ended close to the bedrock, to unravel the earliest history of Lake Ohrid and its basin development. 26Al/10Be dating of clasts from the base of the DEEP sediment succession implies that the sedimentation in the modern basin started at c. 2 Ma. Geophysical, sedimentological and micropalaeontological data allow for chronological information to be transposed from the DEEP to the Pestani succession. Fluvial conditions, slack water conditions, peat formation and/or complete desiccation prevailed at the DEEP and Pestani sites until 1.36 and 1.21 Ma, respectively, before a larger lake extended over both sites. Activation of karst aquifers to the east probably by tectonic activity and a potential existence of neighbouring Lake Prespa supported filling of Lake Ohrid. The lake deepened gradually, with a relatively constant vertical displacement rate of ~0.2 mm a−1 between the central and the eastern lateral basin and with greater water depth presumably during interglacial periods. Although the dynamic environment characterized by local processes and the fragmentary chronology of the basal sediment successions from both sites hamper palaeoclimatic significance prior to the existence of a larger lake, the new data provide an unprecedented and detailed picture of the geodynamic evolution of the basin and lake that is Europe’s presumed oldest extant freshwater lake.
    Keywords: ddc:551 ; Balkan Peninsula ; Lake Ohrid ; DEEP sediment succession ; Pestani succession ; evolutionary dynamics ; regional climate history
    Language: English
    Type: doc-type:article
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  • 2
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    High geothermal heat flow beneath Thwaites Glacier in West Antarctica inferred from aeromagnetic data (2021)
    Nature Publishing Group UK
    Details
    Publication Date: 2024-01-15
    Description: Geothermal heat flow in the polar regions plays a crucial role in understanding ice-sheet dynamics and predictions of sea level rise. Continental-scale indirect estimates often have a low spatial resolution and yield largest discrepancies in West Antarctica. Here we analyse geophysical data to estimate geothermal heat flow in the Amundsen Sea Sector of West Antarctica. With Curie depth analysis based on a new magnetic anomaly grid compilation, we reveal variations in lithospheric thermal gradients. We show that the rapidly retreating Thwaites and Pope glaciers in particular are underlain by areas of largely elevated geothermal heat flow, which relates to the tectonic and magmatic history of the West Antarctic Rift System in this region. Our results imply that the behavior of this vulnerable sector of the West Antarctic Ice Sheet is strongly coupled to the dynamics of the underlying lithosphere.
    Description: The Amundsen Sea sector, Antarctica, is underlain by shallow Curie depths – where the magnetic properties of rocks change – according to airborne magnetic data. This suggests high geothermal heat flow in this region of the West Antarctic Rift System.
    Description: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Alfred-Wegener- Institute, Helmholtz Centre for Polar and Marine Research) https://doi.org/10.13039/501100003207
    Description: European Space Agency (ESA) https://doi.org/10.13039/501100000844
    Description: Deutsche Forschungsgemeinschaft (German Research Foundation) https://doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.932452
    Keywords: ddc:551.1 ; Cryospheric science ; Geomagnetism ; Geophysics ; West Antarctica ; Amundsen Sea sector
    Language: English
    Type: doc-type:article
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