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Salt structures and their surroundings can play an important role in the energy transition related to a number of storage and energy applications. Thus, it is important to assess the current and future stability of salt bodies in their specific geological settings. We investigate the influence of ice sheet loading and unloading on subsurface salt structures using physical models based on the geological setting of northern Germany, which was repeatedly glaciated by the Scandinavian Ice Sheet during the Pleistocene. Apparent spatial correlations between subsurface salt structures in northern Germany and Weichselian ice marginal positions have been observed before, and the topic is a matter of ongoing debate. Recently described geomorphological features – termed surface cracks – have been interpreted as a direct result of ice-sheet-induced salt movement resulting in surface expansion. The spatial clustering and orientation of these surface cracks has not been well understood so far, owing to only a limited number of available studies dealing with the related salt tectonic processes. Thus, we use four increasingly complex physical models to test the basic loading and unloading principle, to analyze flow patterns within the salt source layer and within salt structures, and to examine the influence of the shape and orientation of the salt structures with respect to a lobate ice margin in a three-dimensional laboratory environment. Three salt structures of the northern German basin were selected as examples that were replicated in the laboratory. Salt structures were initially grown by differential loading and buried before loading. The ice load was simulated by a weight that was temporarily placed on a portion of the surface of the models. The replicated salt structures were either completely covered by the load, partly covered by the load, or situated outside the load extent. In all scenarios, a dynamic response of the system to the load could be observed; while the load was applied, the structures outside the load margin started to rise, with a decreasing tendency with distance from the load margin, and, at the same time, the structures under the load subsided. After the load was removed, a flow reversal set in, and previously loaded structures started to rise, whereas the structures outside the former load margin began to subside. The vertical displacements during the unloading stage were not as strong as during the load stage, and thus the system did not return to its pre-glaciation status. Modeled salt domes that were located at distance from the load margin showed a comparably weak reaction. A more extreme response was shown by modeled salt pillows whose margins varied from sub-parallel to sub-perpendicular to the load margin and were partly covered by the load. Under these conditions, the structures showed a strong reaction in terms of strain and vertical displacement. The observed strain patterns at the surface were influenced by the shape of the load margin and the shape of the salt structure at depth, resulting in complex deformation patterns. These physical modeling results provide more evidence for a possible interplay between ice sheets and subsurface salt structures, highlighting the significance of three-dimensional effects in dynamic geological settings. Our results lead to a better understanding of spatial patterns of the surface cracks that were mapped at the surface above salt structures and offer further room for interpretation of the influence of salt movements on the present-day landscape. [ABSTRACT FROM AUTHOR]

Salt structures and their surroundings can play an important role in the energy transition related to a number of storage and energy applications. Thus, it is important to assess the current and future stability of salt bodies in their specific geological settings. We investigate the influence of glacial loading and unloading on subsurface salt structures using physical models, based on the example of the Scandinavian Ice Sheet in northern Germany. Apparent spatial correlations between subsurface salt structures in northern Germany and Weichselian ice marginal positions have been observed before and the topic is a matter of ongoing debate. Recently described geomorphological features – termed surface cracks – have been interpreted as a direct result of ice sheet induced salt movement resulting in surface expansion. The spatial clustering and orientation of these surface cracks was so far not well understood, owing to only a limited number of available studies dealing with the related salt tectonic processes. Thus, we use four increasingly complex physical models to test the basic loading and unloading principle, to analyze flow patterns within the source-layer salt and within salt structures, and to examine the influence of the shape and orientation of salt structures with respect to a lobate ice margin in a three-dimensional laboratory environment. Three salt structures of the northern German basin were selected as examples that were replicated in the laboratory. Salt structures were initially grown by differential loading, and buried before loading. The ice load was simulated by a weight that was temporarily placed on a portion of the surface of the models. The replicated salt structures were either completely covered by the load, partly covered by the load, or were situated outside the load extent. In all scenarios, a dynamic response of the system to the load could be observed: while the load was applied, the structures outside the load margin started to rise, with a decreasing tendency with distance from the load margin and, at the same time, the structures under load subsided. After the load was removed, a flow reversal set in and previously loaded structures started to rise, whereas the structures outside the former load margin began to subside. The vertical displacements during the unloading stage were not as strong as during the load stage, and thus the system did not return to its pre-glaciation status. Modeled salt domes that were located at distance from the load margin showed a comparably weak reaction. A more extreme response was shown by modeled salt pillows whose margins varied from sub- parallel to sub-perpendicular to the load margin, and were partly covered by the load. Under these conditions, the structures showed a strong reaction in terms of strain and vertical displacement. The observed strain patterns at the surface were influenced by the shape of the load margin and the shape of the salt structure at depth, resulting in complex deformation patterns. These physical modeling results provide more evidence for a possible interplay between ice sheets and subsurface salt structures, highlighting the significance of three-dimensional effects in dynamic geological settings. Our results lead to a better understanding of spatial patterns of the surface cracks that were mapped at the surface above salt structures. [ABSTRACT FROM AUTHOR]

The “tablelands” in Taiwan are sedimentary terraces occurring in the foreland basin west of the Neogene mountain ranges. The Miaoli Tableland consists of elevated Late Quaternary sedimentary successions, representing a change from tidal to coastal and fluvial to eolian depositional environments. The present-day morphology is a result of combined processes, including differential tectonic uplift, ongoing fluvial aggradation, and incision. Selected deposits in 10 outcrops were sampled and studied by optical dating. The deposition of fluvial sediments started after the last interglacial (<100 ka) in the southeast of the tablelands. Uplift and sea-level lowering caused a base-level fall, resulting in a stepwise redeposition of the fluvial sediments. Additionally, enhanced remobilization of fluvial sediments occurred during the cold/dry climate during Marine Oxygen Isotope Stages (MIS) 4 and 2. The depositional ages of the coastal sediments enabled the estimation of long-term uplift rates of ca. 0.5 to 3.5 mm/yr. The eolian cover sediments yielded MIS 3 (east) to Holocene ages (west). Our results provide new insight into the interplay of climate, sea-level changes, remobilization of sediments, and tectonism leading to tableland formation during the Late Quaternary. [ABSTRACT FROM AUTHOR]

Significant progress was made in dating of Weichselian sediments in the south-western sector of the Scandinavian Ice Sheet (SIS) in Sweden, Denmark and Germany. Most ages are based on luminescence dating of glaciofluvial and glaciolacustrine sediments, and cosmogenic nuclide exposure dating of glacial boulders. The increasing number of numerical data gives new insights into the timing of various glacigenic, glaciofluvial and glacilimnic processes (Hughes et al., 2016). In Germany, the traditional names of ice advances like Brandenburg, Frankfurt and Pomeranian advance pretend a synchronous formation of ice marginal positions over some distance, not taking into consideration the varying ice dynamics at the distal part of the SIS. In this study, we review existing data and present a revised model of Weichselian ice dynamics in the SW sector of the Baltic Sea.During the early MIS3, according to the present knowledge, the Ellund-Warnow advance marks the first expansion of glaciers during the Weichselian into the SW Baltic Sea area. But it is only lithostratigraphically documented in western Mecklenburg and in parts of Schleswig-Holstein. During late MIS 3, the ice attained the maximum extent within the Oder lobe (Brandenburg advance) and reached into Denmark (Klintholm advance) (Hardt et al., 2016). Nevertheless, there is no evidence that Bornholm, the Rønne Bank as well as Rügen were overridden by ice at that time; instead glaciofluvial and glaciolacustrine sediments were deposited in ice dammed lakes. The area shaped by the maximum ice advance of the Oder lobe, dated to 32-28 ka, is mainly characterized by meltwater sediments and erosional channels, which are in accordance with the assumption of a fast flowing ice of an outlet glacier. Distinct terminal moraines are missing. Thus, various sedimentary environments existed in close neighborhood in the southwestern Baltic Sea basin and the surrounding areas, shedding new light on ice dynamics. The ice advance in correspondence with the global LGM at about 22-20ka, named Pomeranian advance in NE Germany, (Lüthgens & Böse 2011, Lüthgens et al. 2011), was likely characterized by slower moving ice, which can be deduced from the boulder-rich and distinct end moraines in northern Brandenburg, Mecklenburg-Vorpommern and in Schleswig-Holstein. Isochronic ice cover is also documented in the Baltic Sea basin and Denmark. The configuration and dynamics of the SIS in its southwestern part was therefore very different during the MIS 3 and MIS 2 ice advances, influenced by climatic parameters, and the topography of the Baltic Sea basin and adjacent areas. Hardt, J., et al., 2016: Geochronological (OSL) and geomorphological investigations at the presumed Frankfurt ice marginal position in northeast Germany. Quaternary Science Reviews 154, 85-99.Hughes, A., et al., 2016: The last Eurasian ice sheets – a chronological database and time-slice reconstruction, DATED-1. Boreas 45, 1-45.Lüthgens, C., Böse, M., 2011: Chronology of Weichselian main ice marginal positions in north-eastern Germany. E&G Quaternary Science Journal 60, 236-247.Lüthgens, C., et al., 2011: Age of the Pomeranian ice‐marginal position in northeastern Germany determined by Optically Stimulated Luminescence (OSL) dating of glaciofluvial sediments. Boreas 40, 598-615. [ABSTRACT FROM AUTHOR]