Strain partitioning across a fold and thrust belt: the Rhenish Massif, Mid-European Variscides

Transformation of a magmatic arc and an orogenic root during oblique collision and it’s consequences for the evolution of the European Variscides (Mid-German Crystalline Rise)

“…The Rhenohercynian proper shows evidence of foreland-directed thrusting followed in the more internal parts by increasingly W-directed thrusting (Oncken 1988a, Dittmar et al 1994. Cleavage dating and flysch ages indicate an orogenic wedge propagating NW from 370 until 300 (Ahrendt et al 1983, Ruchholz 1989.…”

“…The southern part of the wedge exhibits a late stage sinistral shearing at 312 Ma with significant orogen-parallel stretching, and subsequent dextral shearing (Klu¨gel 1995). This kinematic picture of the detached Rhenohercynian sediments has been interpreted as evidence of oblique convergence with the Saxothuringian upper plate (Oncken 1988a, Dittmar et al 1994, Klu¨gel 1995.…”

“…The Rhenohercynian upper crust has been shortened by 52% on average starting from a more than 350 km wide shelf (Dittmar et al 1994, Oncken et al 1997. The preservation of slope and rise sediments in the southernmost imbricates indicates that no shelf material was lost by subduction (Dittmar 1995).…”

“…The Rhenohercynian zone to the north, an inverted and stacked passive margin sequence (Franke and Oncken Behr 1966, Donsimoni 1981, Ka¨mpfe 1984, Schmidt et al 1986. Inset shows Variscan zones sensu Kossmat (1927) in central Europe (RH: Rhenohercynian, ST: Saxothuringian, MO: Moldanubian) 1990, Dittmar et al 1994, Oncken et al 1996 was underthrust beneath the so-called Saxothuringian zone to the south. One of the consequences expected is considerable thickening from crustal stacking in the collisional area which, during the Permo-Carboniferous, was reequilibrated to normal crustal thickness.…”

Sulphur isotope geochemistry of black shale-hosted antimony mineralization, Arnsberg, northern Rhenish Massif, Germany: implications for late-stage fluid flow during the Variscan orogeny

“…The deformational front progressed from south to north; peak metamorphic ages range from 327-318 Ma in the south to 305-290 Ma at the northern margin (Ahrendt et al 1983). Metamorphic conditions have generally not exceeded very low grade, with peak metamorphic temperatures in the range of 180-320 8C (Oncken 1991;Dittmar et al 1994). Late-orogenic evolution is characterized by the transition from compressional to extensional conditions, related to the Late Palaeozoic strike-slip regime in Central Europe (Arthaud & Matte 1977;Henk 1995).…”