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Abstract

Brittle-ductile transition is estimated on the basis of pore-pressure dependent frictional failure in the brittle regime, and power-Iaw steady-state creep in the ductile regime. Structure and lithological composition of the Centrallberian Peninsula Crust combined with geotherm are used to generate rheological profiles. Two brittle-ductile transitions are shown in the crust. The shallower one is located at "" 7 km under compressional stress es, and at "" 9 km under tensional stresses. The deepest is located at the top of the middle crust, at "" 14 km in compression and "" 17 km in tension regime. Below it, the material is ductile throughout, with a jump in strength at the Moho, which is a main rheological discontinuity. Upper part of lithospheric mantle behaviour is dominated by brittle mechanisms when the crust thickness is30 km, but ductile mechanisms prevail in 34 km crust thickness.