Buried Quaternary valleys in the south-western Baltic Sea (BurVal-Baltic)

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This project strives for understanding the tectonic control on Buried Valley evolution. Buried Valleys (subglacial channels) are defined as deep channel-form features incised into the pre-Quaternary sedimentary record from glaciated terrains. These cut and fill structures have been a matter of intense debate in recent studies as they hold significant supplies of groundwater, they contain aggregate for construction and typically have a most complete sedimentary record of glacial geological processes and paleo-climate conditions. Their formation is generally attributed to subglacial melt-water transport incising the underlying strata during periods of glacial coverage. Several authors noticed a spatial correlation between Buried Valleys and tectonic faults beneath; however, a principle causative correlation was never established. For the suggested study we hold a dense profile grid comprising ca. 20.000 km of multi-channel and ca. 6.000 km of parametric sediment echosounder data from the south-western Baltic. These data allow for the first time a study of Buried Valley evolution on a basin wide scale by means of data that resolve both the detailed valley and valley fill geometry as well as faults and folds within the Post-Permian succession beneath. According to a preliminary interpretation of some profiles we elaborated the following working hypotheses to be tested: 1) The Post-Permian succession has been dissected by abundant near vertical faults. 2) The largest and most densely spaced Quaternary near vertical faults are associated with few kilometers wide and some 10 m high anticlines. 3) In some instances the observed fault-anticline assemblages are associated with vertical fluid migration. 4) The fault-anticline evolution facilitated and thus spatially controlled the incision of Buried Valleys. 5) The near vertical faults and associated anticlines result mainly from ice-load induced tectonics. We will approach these hypotheses by seismic interpretation. Hypotheses 1-4 will be tested by systematic mapping and quantification of Buried Valleys, near vertical faults and anticlines as well as seismic indicators for fluids. The ice-load induced tectonic concept is based on previously published, but rather local studies. Regarding this concept the here proposed project is a first and crucial step to quantify (ice-load induced) recent tectonics and its meaning for Quaternary geology on a basin wide scale. If the hypotheses hold, the resulting models bear the potential to influence Quaternary research in all regions of high latitudes which were temporally ice-covered. The expected abundance of near vertical faults which cross-cut the post-Permian strata represent possible fluid migration paths, which would represent important constrains for all applications which include models about ground water circulation.