Surface cracks—geomorphological indicators for late Quaternary halotectonic movements in Northern Germany

Abstract

Loading and unloading effects of the Scandinavian Ice Sheet triggered halotectonic movements in Northern Germany. We present newly detected geomorphological features-termed surface cracks-which indicate a relation between ice sheetinduced salt movement and surface processes. As a part of the Central European Basin System, numerous Zechstein salt structures are abundant in the North German Basin. On the basis of high-resolution digital terrain data, more than 160 surface cracks were mapped in Northern Germany, which were grouped into 30 clusters. Almost all of the surface cracks occur above the top regions of Zechstein salt structures. The surface cracks can be several kilometres long, up to more than 20 m deep and more than 100 m wide. The comparison of the shape of the salt structures and the orientation of the cracks reveals a geometric dependency, indicating that the cracks preferably occur near the crest margins of the salt structures. Furthermore, 3D seismic data from two sites show that subsurface faults originating from salt movement exist beneath the surface cracks. We interpret the cracks as surface ruptures due to ice sheet-induced halotectonic movements. The cracks occur in a variety of Quaternary sediments and landforms. This indicates that widespread halokinetic movements occurred in the region after the last (Weichselian) deglaciation and likely before the thawing of the permafrost, possibly in a time frame from c. 30-20 ka until c. 15 ka.

Deformation of salt structures by ice-sheet loading: insights into the controlling parameters from numerical modelling

“…This study was intended primarily as a parameter study and was not aimed at reproducing any real-world situations. The deformation observed in the models is generally lower than measurements or estimates from field observations, which commonly indicate several tens of metres of displacement (cf., Sirocko et al 2002;Stackebrandt 2005Stackebrandt , 2016Müller and Obst 2008;Al Hseinat et al 2016;Hardt et al 2021). The discrepancy between models and field observations was already observed in a previous modelling study by Lang et al (2014).…”

“…Pleistocene or Holocene salt movements have been inferred for a number of salt structures in this area. However, it remains unresolved if Pleistocene and Holocene salt movements are the continuation of pre-Pleistocene processes controlled by the regional stress field or if ice-sheet loading triggered a reactivation (Sirocko et al 2008;Al Hseinat et al 2016;Hardt et al 2021).…”

From pilot site knowledge via integrated reservoir characterization to utilization perspectives of a deep geothermal reservoir: 3D geological model at the research platform Groß Schönebeck in the Northeast German Basin

“…This may indicate a somehow distorted layering of the strata or just be related to a worse acoustic coupling due to higher thicknesses of younger sediments with low densities. From surface studies, Hardt et al (2021) interpret Quaternary landforms to result from the interaction of glacial tectonics and halo tectonics. Their location corresponds to the area where the deep fracture are assigned in the 3D seismic volume.…”

Ice dynamics in the SW sector of the Scandinavian Ice Sheet (SIS) – a fresh perspective from the classical area of the Weichselian glaciation in northern Brandenburg

“…Information with regard to the geopark can be accessed via the park's website https://www.geopark-eiszeitland.de/ (last access: 28 July 2022). Boulders from the terminal moraine surface were among the first to be dated by means of surface exposure dating (SED) using cosmogenic nuclides (specifically 10 Be) in north-eastern Germany (Heine et al, 2009). Methodological advances in cosmogenic nuclide dating required a recalculation of these ages, which was conducted by , resulting in ages around 18-20 ka, indicating the retreat of the ice front from its G-LGM position at that time.…”

“…The aim of this field trip was to demonstrate the exceptionally wellpreserved and textbook-like geomorphology and sedimentology of the glacial series (Glaziale Serie) of the Pomeranian (W 2 ) ice-marginal position in the Eberswalde-Chorin area, contrasting it with the challenging geomorphological and sedimentological record of the area assigned to the "vanishing" Frankfurt (W 1F ) ice-marginal position. Over the last years, several geomorphological and geochronological studies applying up-to-date methodology (Lüthgens et al, , 2010aLüthgens andBöse, 2011, 2012;Hardt et al, 2015Hardt et al, , 2021Heine et al, 2009;Brauer et al, 2005;Rinterknecht et al, 2006Rinterknecht et al, , 2012 in that broader ; data from Ehlers and Gibbard, 2004).…”