2012 Articles

Arc-parallel strain in a short rollback-subduction system: The structural evolution of the Crotone basin (northeastern Calabria, southern Italy)

Reitz, Margaret Alison; Seeber, Leonardo

Calabria, located in southern Italy, is the exposed part of the forearc in the Ionian/Tyrrhenian subduction-rollback boundary. We present a tectonic model for the evolution of Calabria during the last 12 Ma that incorporates the structure and stratigraphy of the Crotone basin. At the re-initiation of rollback, we document listric normal faults that accommodated a deep-rooted extensional regime. Extension ceased in the Tortonian and did not continue throughout rollback. The middle Tortonian to early Messinian is characterized by distal sedimentation despite rapid rollback. Westward verging thrusts in Tortonian sediments and olistrostrome deposits within the Messinian section can be explained by instabilities in the accretionary wedge during the Messinian salinity crisis. Tectonic quiescence returned to the basin after the crisis and continued until a north-south shortening event in the middle Pliocene. Our kinematic data and new evidence of two basin inversions suggest arc-parallel shortening of the forearc. We propose that this shortening correlates with the passage of the forearc through the Apulia-Nubia narrow. This data also dispute previous interpretations of the Crotone basin as a pull-apart or transtensional basin. The identification of the main structures in the Crotone basin suggest a shift from quiescence to upheaval, beginning with Pliocene arc-parallel shortening associated with the passage of the forearc through the Apulia-Nubia narrow and continuing until today.