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End date: 2024 × Start date: 2020 × Type: article × Publisher: Amsterdam [u.a.] : Elsevier × WGL Institute: LIAG ×

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    Seismic interpretation and structural restoration of the Heligoland glaciotectonic thrust-fault complex: Implications for multiple deformation during (pre-)Elsterian to Warthian ice advances into the southern North Sea Basin
    (Amsterdam [u.a.] : Elsevier, 2020) Winsemann, Jutta; Koopmann, Hannes; Tanner, David C.; Lutz, Rüdiger; Lang, Jörg; Brandes, Christian; Gaedicke, Christoph
    Despite a long history of research, the locations of former ice-margins in the North Sea Basin are still uncertain. In this study, we present new palaeogeographic reconstructions of (pre-) Elsterian and Warthian ice-margins in the southeastern North Sea Basin, which were previously unknown. The reconstructions are based on the integration of palaeo-ice flow data derived from glaciotectonic thrusts, tunnel valleys and mega-scale glacial lineations. We focus on a huge glaciotectonic thrust complex located about 10 km north of Heligoland and 50 km west of the North Frisian coast of Schleswig-Holstein (Northern Germany). Multi-channel high-resolution 2D seismic reflection data show a thrust-fault complex in the upper 300 ms TWT (ca. 240 m) of seismic data. This thrust-fault complex consists of mainly Neogene delta sediments, covers an area of 350 km2, and forms part of a large belt of glaciotectonic complexes that stretches from offshore Denmark via northern Germany to Poland. The deformation front of the Heligoland glaciotectonic complex trends approximately NNE-SSW. The total length of the glaciotectonic thrust complex is approximately 15 km. The thrust faults share a common detachment surface, located at a depth of 250–300 ms (TWT) (200–240 m) below sea level. The detachment surface most probably formed at a pronounced rheological boundary between Upper Miocene fine-grained pro-delta deposits and coarser-grained delta-front deposits, although we cannot rule out that deep permafrost in the glacier foreland played a role for the location of this detachment surface. Restored cross-sections reveal the shortening of the complex along the detachment to have been on average 23% (ranging from ca. 16%–50%). The determined ice movement direction from east-southeast to southeast suggests deformation by an ice advance from the Baltic region. The chronospatial relationship of the thrust-fault complex and adjacent northwest-southeast to northeast-southwest trending Elsterian tunnel valleys implies a pre-Elsterian (MIS 16?) age of the glaciotectonic complex. However, the age of these Elsterian tunnel valleys is poorly constrained and the glaciotectonic complex of Heligoland may also have been formed during an early Elsterian ice advance into the southeastern North Sea Basin. The glaciotectonic complex underwent further shortening and the Elsterian tunnel-valley fills that were incised into the glaciotectonic complex were partly deformed during the Saalian Drenthe and Warthe (1) ice advances.
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    Measuring and evaluating colorimetric properties of samples from loess-paleosol sequences
    (Amsterdam [u.a.] : Elsevier, 2023) Laag, Christian; Lagroix, France; Kreutzer, Sebastian; Chapkanski, Stoil; Zeeden, Christian; Guyodo, Yohan
    Colorimetric measurements are valuable in studying paleoenvironmental changes in sediment archives such as loess-paleosol sequences. These measurements allow for the identification of climate-sensitive minerals such as hematite, goethite, and secondary carbonates, as well as the observation of stratigraphic changes influenced by paleoclimate variations. Herein, a detailed workflow protocol emphasizing mineral abundance extraction by determining true band amplitudes is presented. Moreover, we present a protocol for colorimetric measurements that eliminates container bias, allowing the analysis and re-analysis of stored sediment quickly and inexpensively. Finally, we introduce a new R-package ('LESLIE') for graphical data display and enhancement. The protocol and its validation are demonstrated on the Suhia Kladenetz loess-paleosol sequence of northern Bulgaria. • A detailed workflow protocol eliminating container bias in colorimetric measurements and extracting mineral abundances is presented. • The protocol is independently validated with aid of Attenuated Total Reflectance Fourier Transform mid-infrared (ATR-FTIR) spectroscopic experiments. • Stratigraphic color enhancement using the R-package 'LESLIE' is facilitated by a user-friendly R-shiny application.