The KTB boreholes that were drilled from 1989 to 1994 near Windischesc
henbach, NE Bavaria, penetrated rocks of the Zone Erbendorf-Vohenstrau
ss (ZEV). The upper and lower sections of the 9101m-deep profile are m
ainly composed of gneiss units (former greywacke sediments) and varieg
ated units (alternating gneisses and metabasites, probably of volcanos
edimentary origin). Metabasic units (amphibolites, metagabbros) consti
tute mainly the middle section. Geochemical data suggest their derivat
ion from oceanic crust. All rocks are probably pre- to early Ordovicia
n in protolith age. They underwent early Devonian MP metamorphism. Rel
ies of preceeding HP metamorphism are preserved in metagabbros. Felsic
to mafic dykes (dominantly Upper Carboniferous lamprophyres) crosscut
the metamorphic rocks. The ZEV units are steeply inclined down to the
final depth. The main structures (foliation, folds, faults) trend NW-
SE. Semibrittle to brittle deformation plays an unexpected important r
ole. In contrast to the conditions of the Mesozoic (mainly Cretaceous/
Tertiary) faulting the P-T conditions of MP metamorphism, the cooling
ages and the late-Variscan graphite-bearing prehnite-actinolite facies
mineralization show no significant depth-dependent gradients. This ca
n be explained by Mesozoic supracrustal stacking. A bundle of reverse
faults between 6850 and 7300 m belongs to the Franconian lineament and
can be correlated with the most prominent seismic reflector (SE1) in
the area.