Ice sheet induced salt tectonics – the example of surface cracks in northern Germany

<p>The underground of the northern German lowlands, located in the Central European Basin System (CEBS), is characterized by numerous Permian Zechstein salt structures, which are found at depths of up to more than 2000m. The lowlands were transgressed several times by the Scandinavian Ice Sheet during the Pleistocene glacial cycles. Several researchers have noted that there seems to be a spatial correlation between the positions of Weichselian end moraines in Northern Germany and subsurface salt structures. Thus, it was assumed that the pressure of the advancing ice sheet triggers salt tectonic movements, which in return influences the spatial configuration of the ice extent.</p> <p>Using high resolution laser scan digital elevation models, we have recently mapped more than 150 linear negative landforms (up to several km in length, up to 20 m in depth and up to more than 100 m in width) in northern Germany that we term &#8220;surface cracks&#8221; and which we interpret as surface expansion ruptures caused by ice sheet induced salt movements related to the last glacial cycle (Weichselian glaciation). This interpretation is based on: (1) geomorphological analyses, which also allow for a relative geochronological classification; (2) a reassessment of existing theoretical models on ice sheet induced salt movement, and; (3) new physical modeling experiments. Our results shed a new light on the geomorphology of the northern German young morainic landscapes, illustrating an active interplay between climate (glaciations) and loading-induced subsurface motions (buried salt structures).</p>