Shearing of syn-sedimentary carbonate breccia along strike-slip faults, Altamura Fm., Southern Italy

Salvatore Laurita (1), (2), Fabrizio Agosta (1), (2), Francesco Cavalcante (3), Andrea Rustichelli (2), (4) & Maurizio Giorgioni (5)
(1) Department of Science, University of Basilicata, Italy. Corresponding author e-mail: salvatorelaurita@hotmail.it
(2) Reservoir Characterization Project (www.rechproject.com).
(3) Institute of Methodology for Environmental Analyses, CNRTito scalo (Potenza), Italy.
(4) School of Science and Technology, University of Camerino, Italy.
(5) Shell Italia E&P, Rome, Italy.

Fault breccia present along strike-slip faults was studied by mean of an integrated field and laboratory investigation. In particular, samples of sheared pre-existing, syn-sedimentary gravitative breccia were detailed studied in order to decipher the deformation mechanisms associated to strike-slip faulting. The sheared gravitative breccia is made up of matrix-supported, monomictic, unsorted intraformational fragments embedded within a reddish hematiterich, clayish matrix. Microsparry calcite cement is also present around the limestone fragments. In contrast, tectonic breccia consists of comminuted limestone fragments embedded in a calcite-rich matrix also including small amounts of reddish matrix. Particle shape analysis of representative images of the study hand specimens shows a variability of the box-counting dimension (D0-value) between the two different types of breccias, which can be explained in terms of peculiar strain localization within a threefold aggregate that characterizes the gravitative breccia, which is made up of calcite fragments, clayish matrix and very minute oxides.

fault breccia, syn-sedimentary deformation, gravitative breccia, Altamura Fm., Murge Plateau.