Basement topography and thrust fault ramping, a model to explain cleavage fans in the Mosel area (Rheinisches Schiefergebirge)

Abstract

The structure of the Mosel area is characterized by major NW-directed overthrust faults, that formed in a late stage of the deformation history, after two phases of ductile deformation. The traces of the major overthrust faults are indicated by discontinuities in stratigraphy, metamorphic grade and intensity of the pre-thrusting deformation structures. The thrust planes separate rock sequences that have rotated by foreland-directed movement on SE-dipping listric surfaces. Large scale normal and reverse cleavage fans have formed in the hanging wall of the main overthrust planes. It is suggested that the overthrust planes, cleavage fans and the large scale rotations have formed in relation to bending of the detached sedimentary cover over pre-existing ramps in the crystalline basement. These ramps represent inherited normal faults, that formed during syn-sedimentary differentiation of the Lower Devonian sedimentary basin.