3D geological modelling of the surficial aquitards in the German “Central Oder” sub-catchment.

The „Central Oder“ sub-catchment in Germany is the first of three areas for which structural models of the surficial aquitards down to the latest Elsterian till are being constructed as part of the Geo3D-Oder project. All other areas are interpreted as undifferentiated aquifers. The data base is taken from the "Lithofacies map of the Quaternary 1 : 50,000" (LKQ 50).

The model consists of ten stratigraphic layers, each bounded by a top and base horizon, and the ground surface. The data combines polygons defining the extent of the strata and point data of elevations derived from contour lines and stratigraphic logs. The data was processed and transferred to the SKUA-GOCAD modelling platform.

The geological 3D model contains only a concordant sequence of horizons with no faults. The challenge in constructing 3D models of Quaternary glacial sediments lies in the variable and sometimes very small layer thickness. Especially in the case of unavailable information on the elevation of upper horizons, layers below cannot be correctly reproduced. A new method has been developed to avoid this. For each horizon, the uppermost proven elevations of all underlying strata were identified in search quadrants. This data was used to interpolate 'virtual horizons', which are constraints on the maximum depth for each horizon. The resulting horizons were finalised using automated routines and manual post-processing.