RIGO, LUCA, and MARY WELKER-HADDOCK, Maxus Energy, Dallas, TX

ABSTRACT: Structural Style of Cretaceous Compression in the Northern Bohemian Massif of Eastern Germany

The Bohemian massif was subjected to regional compressional stresses during Late Cretaceous Alpine, Dinaric, and Carpathian tectonic events. Older Mesozoic extensional and Variscan compressional fault planes were reactivated as decollement surfaces during this Late Cretaceous compression. Seismic profiles and geologic data suggest that Cretaceous faults are rooted in low-angle detachments and predominately compressional. In addition, a sinistral shear component is oriented oblique to the northwest-striking compressional component.

The northern extremity of the Bohemian massif in eastern Germany is represented by the Thuringen, Harz, Flechtinger, and Calvoerde basement uplifts. The Thuringen block is bordered by a southwest-verging thrust fault, whereas the other three features are formed by a series of northeast-verging, northwest-striking, thrust faults. The Calvoerde structure is the northeasternmost basement-rooted feature in the Bohemian massif. As this structure approaches the Variscan Altmark paleohigh to the northwest, the fault decreases its throw and forms a lateral ramp. In the central European depression and Subhercynian basins, compressional stresses are transferred to decollement surfaces within Zechstein evaporites, creating halokenetic structures and reverse faults.

The application of a compressional model creates additional hydrocarbon exploration opportunities in traditional reservoirs such as the Rotliegendes and Carboniferous in northern Germany. The model allows for the reinterpretation of some of the normal faults as oblique reverse shear faults. This holds particularly true for normal faults associated with Cretaceous halokenetic structures. The additional reverse and thrust faults will generate an inventory of previously untested footwall traps.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.