Title of article :
Fault architecture and deformation mechanisms in exhumed analogues of seismogenic carbonate-bearing thrusts
Author/Authors :
Tesei، نويسنده , , Telemaco and Collettini، نويسنده , , Cristiano and Viti، نويسنده , , Cecilia and Barchi، نويسنده , , Massimiliano R.، نويسنده ,
Issue Information :
ماهنامه با شماره پیاپی سال 2013
Abstract :
Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC′ tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of “aseismic” behaviour.
Keywords :
Microstructures , SEISMIC BEHAVIOUR , Fault complexity , carbonates
Journal title :
Journal of Structural Geology
Journal title :
Journal of Structural Geology