This paper investigates the time‐transgressive evolution of the Fennoscandian Ice Sheet (FIS) during the Late Weichselian glaciation. Recent models of the Last Glacial Maximum (LGM) strongly challenge a synchronous development of the FIS in the SW Baltic Sea area. Especially in northern Germany, a time‐transgressive LGM is controversial. We present a new set of optically stimulated luminescence (OSL) ages, from sediments deposited at locations previously ascribed to the LGM main stationary line, from which numerical age data have not been published so far. The aim of this study was to contribute to the research on the maximum Weichselian ice extent in northern Germany, and to close the gap between Denmark in the north and the area in Germany and Poland in the SE, for which numerical age data of the LGM extent of the FIS are available. Samples were taken from sandur deposits proximal to the former ice margin. In total nine OSL samples were taken and analysed on quasi‐single‐grain level, taking into account possible effects of insufficient bleaching of sample material. With an average age of ~23±1 ka, the samples indicate LGM sandur formation during Marine Isotope Stage (MIS) 2. Our dating provides new insights into Late Weichselian (MIS 2, 27–11.7 ka) ice‐sheet dynamics and strongly challenge a synchronous development of the FIS in the SW Baltic Sea area. The integration of our results into regional models argues for a small‐scale asynchronous extent of the last FIS in northern Germany.
Mesozoic vertebrate fossils within glacially transported deposits of Pleistocene age are rare. Here, we examine five isolated, strongly eroded vertebrae of Mesozoic marine reptiles, most probably plesiosaurs, from glacigenic sediments of northern Germany. In addition, three consecutive plesiosaur vertebrae, having already been described in previous publications, are briefly reconsidered. For one heavily eroded specimen, litho- and biostratigraphical analyses of associated sediment, including thin sectioning and calcareous nannofossil investigations, confirm a mid-Cretaceous age. The internal morphology of the five isolated vertebrae in focus, investigated with the help of microCT, reveals the presence of (neuro)vascular cavities within the respective centra. Unexpectedly, we found diverse internal cavity patterns which have only one feature in common: a medial pair of foramina on the floor of the neural canal that is connected to deep-reaching canals.
We present a detailed study of an alluvial fan accumulated in a piggyback basin syn-kinematically to the emergence of a Weichselian glacitectonic complex (Jasmund peninsula, SW Baltic Sea). Although sediments formed contemporaneously with glacitectonic events have already been documented, a systematic approach is missing so far. Facies, architecture and distribution of alluvial-fan deposits are identified here as key features for analyzing glacitectonic complexes.The deposition of those syn-kinematic deposits was controlled by the progradation of thrust-faults and the resulting morphologic changes of both the thrust-bounded ridges and the adjacent piggyback basins. Another controlling factor is the episodic high runoff of meltwater discharge (glacial lake outburst flood, jo spacing diaeresis kulhlaup) from lakes near the ice front. Sheetflood and debris-flow processes dominated the sedimentation and gave way to alluvial-fan, fan-delta and glacifluvial deposits. A stepwise rotation of the depositional plain within the piggy-back basin is indicated by internal unconformities and the distinct converging stratal geometry. Based on three luminescence ages the development of the syn-kinematic alluvial-fan sequence and consequently of the glaci-tectonic complex took place between 21 and 19 ka during a late Weichselian readvance of the Scandinavian Ice Sheet. The overall results are summarized in a seven-stage genetic model, beginning with the initial glacitectonic phase and ending with the overfilled piggyback basin and subsequent overriding of the structure by the glacier front. With the presented criteria, the successive growth of the alluvial-fan deposits can be linked directly with the emergence of a glacitectonic complex formed during an ice advance.
The age of the push moraine complex Wallsbüll-Böxlund, Schleswig-Holstein, is unclear despite investigations in this area for decades. To address the timing of formation of both the push moraine complex and the peat and soils found in its depressions, an outcrop in Osterbylund (OBL) was investigated. Optically stimulated luminescence and 230Th/U dating, as well as pollen analyses, were undertaken with the aim to correlate the soils OBL 1 to OBL 4 to interglacials and interstadials. The chronological studies were accompanied by detailed sedimentological investigations. The results of the pollen analyses put the peat unambiguously to the Eemian; the peat is equivalent to OBL 1. The overlying sands and the other intercalated soils are to be placed into the early Weichselian. While for OBL 2 the assignment to the Brörup interstadial is clear, it is more difficult to clearly correlate OBL 3 and OBL 4 to an interstadial due to poor luminescence signal resetting of the sands, especially above OBL 4. Considering all data available, it is most likely that OBL 3 formed during the Odderade interstadial and OBL 4 during the Keller interstadial. From the Eemian to early Weichselian ages of the peat and soils it is evident that the push moraine complex is of Saalian age; a Weichselian ice margin further in the west, as assumed in other studies, can therefore be excluded.
The development of the Fennoscandian Ice Sheet (FIS) in its SW Baltic Sea sector during MIS 2 led to the formation of the Jasmund Glacitectonic Complex (JGC). The evolutional stages of the latter reflect small-dimensioned ice sheet oscillations. A glacitectonically formed piggyback basin is in focus to give direct information on the evolution of the JGC. We present a set of five OSL ages from syn-kinematic glacilacustrine and alluvial fan sediments deposited between ice margin-parallel thrust-bounded ridges from the southern margin of the JGC. The ice front proximal depositional environment and short transport distances of the sediments implicate a possible insufficient bleaching of the luminescence signal. Nonetheless, we were able to gain reliable ages of ~22 ka for the growth of the southern JGC. The samples pre-date the Oder ice stream reaching its maximum extent, the Pomeranian ice marginal belt at ~18–20 ka. A comparison of our data with the existing age data related to the evolution of the JGC will contribute to a better understanding of the FIS dynamics in the research area and the timing of the Pomeranian phase in NE Germany.
A sedimentological, geochronological, and geodynamic investigation of detailed micro- and meso-scale soft-sediment deformation structures (SSDS) within internally deformed layers on Gnitz Peninsula, Usedom Island, Germany, was performed in the last years. Five layers with SSDS were described of which four were possibly caused by glacial isostatic adjustment (GIA)-triggered earthquakes mirrored in liquefaction and reliquefaction phenomena (Pisarska-Jamroży et al., 2022). Hence, in line with earlier investigations and suggestions by Hoffmann and Reicherter (2012), the SSDS generation is related to oscillation of the Scandinavian Ice Sheet whose loading cycle caused stress changes likely releasing local earthquakes along pre-existing faults.Optically stimulated luminescence dating indicates a most probable time span of corresponding earthquake occurrence between 23.2 and 14.6 ka (including uncertainty). For the first time, glacially induced Coulomb failure stress changes were modelled for this area with a set of commonly accepted GIA models. They strongly support the interpretation of SSDS trapped in layers as seismites during that time. Using reliable fault parameters of faults in near vicinity of Gnitz Peninsula and suggested stress regimes and directions for northern Germany, the modelling can help indicate the most probable reactivated pre-Quaternary fault(s). If they can be confirmed after detailed palaeoseismological, geomorphological, geophysical, and structural investigations as so-called glacially induced fault(s), this would add another puzzle piece to a geodynamic scenario of glacially triggered faulting having affected an area from northern central Europe to northern Fennoscandia in the Late Pleistocene and Early Holocene.Our presentation will focus on the geodynamic setting of NE Germany, how it was changed during the last glaciation and how potentially reactivated faults can be determined.ReferencesHoffmann, G., Reicherter, K., 2012. Soft-sediment deformation of late Pleistocene sediments along the southwestern coast of the Baltic Sea (NE Germany). Int. J. Earth Sci. 101, 351-363, doi:10.1007/s00531-010-0633-z.Pisarska-Jamroży, M., Belzyt, S., Börner, A., Hoffmann, G., Kenzler, M., Rother, H., Steffen, R., Steffen, H., 2022. Late Pleistocene earthquakes imprinted on glaciolacustrine sediments at Gnitz Peninsula (Usedom Island, NE Germany). Quat. Sci. Rev. 296C, 107807, doi:10.1016/j.quascirev.2022.107807.
Weichselian advances of the Scandinavian Ice Sheet have generated several glacitectonically deformed structures in the southwestern Baltic Sea area. One example is the 100 km2 large Jasmund Glacitectonic Complex (JGC), which was formed proglacially and consists of two subparallel-orientated sets of composite ridges that represent a northern and southern structural complex. The two-part morphological structure of the JGC suggests a formation by two ice advances, one approaching from NE and one from SE direction. So far, this divided structure has been assumed to have been formed by short-time ice-front oscillations during an MIS 2 ice advance. However, based on their recently published ice dynamic model for MIS 3 and the available age data from Jasmund, luthgens et al. (2020) propose a chronological reinterpretation of the JGC development, according to which two distinct ice advances during early and late MIS 3 formed the JGC. In order to test this novel stratigraphical model for the JGC formation, five OSL samples were taken from fluvial and lacustrine deposits at a key section near Glowe (NW Jasmund). The investigated succession is divided into pre-kinematic sediments, deposited before the glacitectonic deformation, and post-kinematic sediments, deposited after the deformation. Our results show that the youngest dated pre-tectonic sediment has a burial age between-40 and 34 ka, which rules out a glacitectonic deformation during an early MIS 3 ice advance (-60-50 ka). In addition, by reviewing the existing age data set, a development of the JGC during an early and late MIS 3 advance of the SIS must be rejected. Instead, our data confirm the genesis of the JGC during MIS 2.
Oscillation of an ice sheet can be accompanied by earthquakes due to local reactivation of pre-existing faults related to the ice loading. A sufficiently large magnitude of an earthquake can trigger seismic waves that may strongly deform susceptible sediment layers and can cause the development of soft -sediment deformation structures (SSDS). Morphological and structural features of SSDS within a gla-ciolacustrine succession exposed at the coastal cliff on Gnitz Peninsula (Usedom Island) in NE Germany indicate that they must have developed due to glacial isostatic adjustment, which was suggested earlier by Hoffmann and Reicherter (2012).Here we present detailed micro-and meso-scale SSDS within internally deformed layers interpreted as seismites, liquefaction and re-liquefaction sedimentological imprints on Gnitz Peninsula. New optically stimulated luminescence dating results indicate that the most probable time span of corresponding earthquake occurrence is between 23.2 and 14.6 ka. The interpretation of SSDS 'trapped' in layers as seismites is strongly supported by modelling of glacially induced Coulomb failure stress changes in this region. Our results point to a set of probably pre-Quaternary faults which were locally reactivated in the area of Gnitz Peninsula during the last glacial maximum.(c) 2022 Elsevier Ltd. All rights reserved.
Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Piggyback basins are common and well-studied features of thrust belts, but they are also known to form in front of advancing ice sheets. However, these glacitectonically developed basins and their syn-glacitectonic fillings have so far received little attention. Here, we present a detailed study of a cliff section on Jasmund peninsula, SW Baltic Sea, where syn-kinematic deposits of Late Weichselian age (MIS2) accumulated in a piggyback basin. Sedimentological analyses, including micromorphology and field studies, resulted in a distinction of at least five tectono-depositional sequences of syn-glacitectonic basin fills. The sediment record indicates a stepwise evolu-tion of the basin, controlled by propagating thrust faults and the resulting thrust-bound ridge morphology. A fast-changing depositional environment with glacifluvial, glacilacustrine, alluvial fan and fan delta depositional systems, show a rapid transformation of the overall morphology of the study area. The main controlling factors are the propagating thrust faults (determining anticline and syncline orientations) and the advancing ice margin, which caused sudden changes or even temporal obstruction of the meltwater drainage system. The proposed stages of basin evolution illustrate the dynamic formation and stepwise syn-tectonic fill of piggyback basins in glacitectonic complexes. Our evolutionary model will increase our understanding of basin fills on glacitectonic thrust-and fold-belts that were formed by approaching ice sheets in ice-marginal settings.
Abstract. The site at the southern shore of Krakower See shows the Quaternary geology of the surrounding area. The local Quaternary sequence comprises a thickness of 50–100 m of Quaternary deposits while the surface morphology is dominated by the ice marginal position of the Pomeranian moraine, which passes through the area. The bathymetry of the lake basin of Krakower See indicates a predominant genesis by glaciofluvial erosion in combination with glacial exaration. Past research in this area has focussed on the reconstruction of Pleniglacial to Holocene environmental changes, including lake-level fluctuations, aeolian dynamics, and pedological processes and their modification by anthropogenic land use.
Over recent decades a growing number of well-documented records from terrestrial last interglacial sites across central Europe have substantially improved our understanding of Eemian climate and landscape dynamics. Despite this progress, there are also large areas from which little information is available, thus constituting significant paleo-geographic gaps in the last interglacial record. Among the regions with still inadequate paleo-environmental information is the maritime-influenced area of NE-Germany at the southern margin of the Eemian (Baltic) Sea. Here we present first results from a geological investigation of a new last interglacial site, recently discovered during archaeological excavations near Beckentin (SW-Mecklenburg). The study area is located approximately 25 km to the south of the maximum MIS-2 ice limit of the Scandinavian Ice Sheet in NE-Germany, and thus lies outside the Weichselian belt of glaciation. Based on lithostratigraphic and sedimentological logging, complemented by geochemical (XRF) and palynological investigations, we divide the local succession into three sections: (1) a basal facies comprising Saalian till and associated glaciofluvial sand, overlain by section (2) consisting of a fen peat which grades into laminated organic to minerogenic mud. The organic deposits of section (2) preserve a near complete Eemian pollen inventory, encompassing pollen zones (PZ) I to VI (Menke and Tynni 1984). Above this rest poorly sorted periglacial sands (section 3) with ventifacts and evidence for cryogenic deformation. Geochronological results from Th-230/U dating of the buried organic-rich deposits at Beckentin, show that these units accumulated in a former dead ice depression between 118 +/- 7/6 ka and 114 +/- 6/5 ka during the Eemian Interglacial. High-resolution optically stimulated luminescence (OSL) profiling, undertaken with a portable luminescence reader, reveals a significant hiatus between the lacustrine fines and overlying periglacial cover sand. Five OSL ages obtained from these cover sediments and the sand-filling of an ice-wedge cast show that these strata formed between during the last glacial interglacial transition. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.
Abstract. A thrust-bound footwall syncline located within the proximal part of the southern Jasmund Glacitectonic Complex is investigated, exploring the spatio-temporal relationship between glacitectonic macro- and microstructures. Orientation and geometry of macroscale folds and thrust faults reveal a two-phased deformation history recorded by the sedimentary sequence. The deformation is a result of glacitectonic imbrication and subsequent ice flow across Jasmund Peninsula during the late Weichselian. Clast microfabrics preserved within the folded glacial diamicts reveal that till-internal deformation is mainly related to subglacial shearing within the glacier bed, which predates large-scale imbrication and folding.
Abstract. Isostatic response of the Earth's crust as a consequence of the fluctuating extent of ice-sheet masses was accompanied by earthquakes probably due to local reactivation of pre-existing faults. Our study of a glacilacustrine and glacifluvial succession exposed on Rügen Island (SW Baltic Sea) indicates that some of the soft-sediment deformation structures within the succession must have formed shortly before the front of the Pleistocene Scandinavian Ice Sheet reached the study area (during the Last Glacial Maximum), thus during a stage of ice advance. Based on analysis of the textural and structural features of the soft-sediment deformation structures, the deformed layers under investigation are interpreted as seismites which formed as a result of seismically induced liquefaction and fluidisation.
Abstract. Four remarkable Pleistocene cliff outcrops scattered across the peninsula of Jasmund exhibit the dynamics of the Scandinavian Ice Sheet during the Weichselian glaciation in this area. The investigated sites display up to 30 m thick sequences of glacial tills with intercalated (glaci)fluvial to (glaci)lacustrine sediments. Based on detailed lithofacies analyses and a physical age chronology, we trace the reconstruction of the depositional sequences and their corresponding stratigraphic position within the Weichselian record.
Abstract. This paper aims to combine the knowledge of more than 100 years of Quaternary research in Mecklenburg-Western Pomerania (Geinitz, 1922; Deecke, 1907; Schulz, 1967, 1971; von Bülow, 2000; Rühberg et al., 1995; Müller et al., 1995; Katzung, 2004; Kenzler et al., 2015, 2018) including a summary of the areas of specific interest, a general overview of the most recent scientific results and of the ongoing investigations presented during the Field Symposium of the INQUA PeriBaltic Working Group 2019.
It is hitherto commonly thought that earthquakes triggered by geologically rapid changes in the pressure caused by the fluctuating extent of thick land-ice masses occur exclusively during ice retreat. Our study of deformed sediment layers within an undeformed glaciolacustrine and glaciofluvial succession exposed in a coastal cliff on Rügen Island, south-western Baltic Sea, challenges this widespread idea. Based on their structural and deformational features, the layers under investigation are interpreted as seismites which formed as a result of seismically-induced liquefaction. The stratigraphic context aided by optically stimulated luminescence (OSL) dating indicate that the documented seismites must have formed shortly before the front of the Pleistocene Scandinavian Ice Sheet reached the study area during the Last Glacial Maximum, thus during a stage of ice advance. This implies that the flexural isostatic response of the Earth's crust as a consequence of the ice load during ice advance was accompanied by earthquakes probably due to local re-activation of pre-existing faults. The crustal response to an increasing ice load was consequently less gradual than previous studies about glaciation-related tectonics suggest.
Here we present a multi‐proxy investigation of the Klein Klütz Höved (KKH) coastal cliff section in northeastern Germany, involving lithofacies analysis, micromorphology, micropalaeontology, palynology and luminescence dating of quartz and feldspar. We subdivide the local stratigraphy into three depositional phases. (i) Following a Saalian advance (MIS 6) of the Scandinavian Ice Sheet, the penultimate deglaciation (Termination II) at the site occurred between c. 139 and 134 ka, leading to the establishment of a braided river system and lacustrine basins under arctic‐subarctic climate conditions. (ii) In the initial phase of the Eemian interglacial lacustrine deposits were formed, containing warm‐water ostracods and a pollen spectrum indicating gradual expansion of woodlands eventually containing thermophile deciduous forest elements. A correlation of the local pollen assemblages with Eemian reference records from central Europe suggests that fewer than 750 years of the last interglacial period are preserved at KKH. The occurrence of brackish ostracods dates the onset of the Eemian marine transgression at the section at c. 300–750 years after the beginning of the last interglacial period. (iii) Directly above the Eemian record a ~10‐m‐thick sedimentary succession of MIS 2 age was deposited, implying a significant hiatus of c. 90 ka encompassing the time from middle and upper MIS 5e to late MIS 3. During the Late Weichselian, KKH featured a depositional shift from (glacio‐)lacustrine to subglacial to recessional terminoglacial facies, with the first documented Weichselian ice advance post‐dating 20±2 ka. Overall, the KKH section represents an exceptional sedimentary archive for palaeoenvironmental reconstructions, covering the period from the Saalian glaciation and subsequent Termination II to the early Eemian and Late Weichselian. The results refine the existing palaeogeographical and geochronological models of the late Quaternary history in the southwestern Baltic Sea area and allow correlations with other reference records in a wider area.
The study of two cliff outcrops from the Jasmund Peninsula provides new information on the ice‐sheet dynamics and palaeo‐environmental conditions during MIS 3 and the ensuing transition to MIS 2 in the southwestern Baltic Sea region. We identified interstadial fluvial sediments, with mollusc and vertebrate fauna, which were deposited between 47 and 42 ka in a steppe‐like landscape. A subsequent cooling phase led to the formation of a proglacial lake, between 30 and 22 ka, indicated by varve‐like, rhythmically bedded silty clay. This proglacial lake formation can be correlated to the blocking of the Baltic Basin by the Kattegat ice advance, previously dated to c. 29–26 ka. The transition from proglacial to terminoglacial lacustrine deposits reflects the immediate advance of the Scandinavian Ice Sheet (SIS) into the study area after the transition from MIS 3 to early MIS 2. The SIS finally reached the area at 23±2 ka (Brandenburgian phase; advance from the northeast). A subsequent ice retreat accompanied by the deposition of meltwater sediments was followed by a re‐advance of the SIS, resulting in a glaciotectonic deformation event across the study area. The age control for our study is based on optically stimulated luminescence (OSL). The investigated Pleistocene sediments show ice‐free conditions during MIS 3 and early MIS 2, indicating that neither the Ristinge nor the Klintholm advance reached the SW Baltic Sea coast of Jasmund.