Seismic cycle recorded in cockade-bearing faults (Col de Teghime, Alpine Corsica)

Few fault rocks are known to be associated undoubtedly with seismic faulting. Here, we investigated the formation mechanism of cockade breccias found in transtensional faults cutting marbles and quartzites from the Col de Teghime area (Alpine Corsica, France). Field surveys coupled with detailed microanalytical investigations indicated that: (i) the core clasts of the cockades are composed of host rock fragments >310 μm in size that are suspended in the slipping zones and arranged in inverse grading; (ii) the concentric rims of the cockades show a cyclic zoning made of saddle dolomite + Mg-calcite + goethite + anatase; (iii) the cockade-bearing veins are associated with minor fault veins filled with fine fragments (<300 μm in size) cemented by the same minerals of the cockade rims. We propose that the cockade-bearing faults formed at shallow crustal depths (