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Fracture and Faulting |
Geologisch-Paläontologisches Institut der Johann Wolfgang Goethe-Universität, Senckenberganlage 32-34, 6000 Frankfurt a.M., FRG
Within the research well KTB-VB, late- to post-Variscan brittle deformation is widespread, indicating that the well is situated in a broad fault zone. Graphite-enriched foliated cataclasites within paragneisses are probably connected with late-Variscan NW trending reverse faults. These faults were succeeded by further, graphite-free, faults in post-Variscan time. During the formation of the graphitic cataclasites water-consuming retrograde metamorphism was active producing large amounts of phyllosilicates, especially at the expense of feldspar. The increase in phyllosilicates and graphite was associated with a switch of the dominant deformation mechanisms from brittle fracture to frictional sliding, crystal plasticity and diffusion-controlled processes. The cataclastic fabric suggests that the main part of the movement within the graphitic cataclasites was likely to have been aseismic rather than seismic.
