Sulfate rock distribution in Lower Saxony 1 : 500 000 – Viewing range up to 200 m below ground

Description

The overview map of the sulphate rock distribution in Lower Saxony 1 : 500 000 indicates areas where sulphate rocks up to 200 m below surface nicht zu erwarten sind oder potenziell vorhanden sind. The demarcation between the two areas is based on the assessment of comprehensive geoscientific data available at the State Office for Mining, Energy and Geology. Areas without clear information on sulphate rock distribution in the corresponding depth range, as well as areas where the sulphate rocks may already be leached, are generally classified as ‘potentially present sulphate rocks’. The map is updated at regular intervals. Near-surface sulphate rocks (gypsum/anhydrite) pose a threat to drilling, as there may be a new connection of water to sulphate-bearing layers during drilling production. This water connection can lead on the one hand to a conversion of anhydrite into gypsum with accompanying increase in volume and elevation of the terrain and on the other hand to subrosion. The volume increase due to the anhydrite-gypsum conversion decreases with increasing superposition. The present map is based on the assumption that at a depth of = 200 m below the surface of the terrain, there is no longer any fear of an increase in volume that could lead to elevations at the surface. For more detailed information on subrosion, please refer to the map of geohazards in Lower Saxony 1: 25 000 - Earthfall and Subsidence Areas (IGG25). The map is essentially based on Geological Map 1: 50,000 (GK50), the Geotectonic Atlas 3D (GTA3D) as well as the drilling data from the hydrocarbon database and the drilling database of Lower Saxony. For the creation of the map, the sulphate-bearing stratigraphic units Münder Mergel (Malm), Mittlerer Keuper, Mittlerer Muschelkalk, Oberer Buntsandstein, Zechstein and Rotliegend were taken into account. As part of the mapping process, the information from these different data sources was combined and cross-checked using other geological data (see ‘Information on the data’).

Resources

Name Format Description Link
0 https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=916&Service=WMS&Request=GetCapabilities&

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