KINEMATIC ANALYSIS IN THE LIGURIAN UNIT OF EASTERN ELBA ISLAND (ITALY)

Abstract

Collision between the Adriatic and Corso-Sardinian microcontinents occurred in the Late Oligocene to Early Miocene. During this event oceanic crust and pelagic sediments of the Ligurian Ocean (Ligurian Unit) were overthrust onto the western margin of the Adriatic Plate (Tuscan Unit). In this study the fault systems and kinematics in the Ligurian Unit of the eastern Elba Island were studied in order to reconstruct its structural evolution. Fault systems were recognized by detailed mapping between the Volterraio ruin in the south and the Cala dell’Inferno in the north. The geometry and kinematics of the fault and fold systems show that the Ligurian Unit was thrust from the southwest in several imbricated tectonic slices onto the Tuscan Unit. Three tectonic phases were separated. The first one was compressional and related to nappe thrusting. The trajectories of the main compression axes show a trend from WSW-ENE in the western part of the study area to SSW-NNE in the northern part. The second event was linked to post-collisional extension as a gravitational response to nappe stacking. The third event, Pliocenic in age, created extensional as well as compressional features and was triggered by the intrusion and uplift of the eastern Elba pluton. Due to doming above the pluton, northwestward gliding away from the intrusive centre generated an extensional regime at the trailing edge in the eastern part and a compressional regime at the front of the gliding mass in the western part of the study area.