International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

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TRANSTENSIONAL/EXTENSIONAL FAULT ACTIVITY FROM THE MESOZOIC RIFTING TO TERTIARY CHAIN BUILDING IN NORTHERN SICILY (CENTRAL MEDITERRANEAN)

Published: Jun 2005

Pages: 255 - 271

Authors: FABRIZIO NIGRO, PIETRO RENDA

Abstract: Extensional structures of different ages characterize the Sicilian fold-and-thrust belt. Normal faults ranging in geometry from stepped to listric and formed in different geodynamic settings significantly controlled the pattern of syn-tectonic deposits. Since Mesozoic times Sicily has experienced deformation related to the opening of the Tethys Ocean. Between the Upper Triassic and the Cretaceous normal, strike- and oblique-slip faults, developed in northern Sicily, in the framework of a transtensional deformation regime induced by the oblique rifting of the African and European continental passive margins. Since Tertiary times a reversal in the general relative plate motion induced convergence, followed by collision of the European and African margins. Neogene compressional deformations were locally associated to extensional structures related to the orogenic wedge taper and to the Pliocene-Pleistocene Tyrrhenian Basin evolution. The persistent activity of extensional structures at different times and within different tectonic pictures is magnificently preserved in the following Triassic-to-Recent stratigraphic record: (i) carbonates were deposited on the Jurassic passive margin, formed by neritic platforms and intervening pelagic basins; (ii) the Cretaceous extension in the Africa plate boundary followed Late Triassic-Early Jurassic transtension due to Neotethys stretching; (iii) clastic deposition occurred during Neogene chain building ahead of the advancing thrust front (foredeep deposition) and in the inner sectors of the orogenic wedge (perched deposition in extensional setting); (iv) the perched-basin deposition at the rear of the wedge was probably related to the extensional collapse of the taper during the Late Miocene and (v) the attenuation of previously thickened lithosphere corresponds to the onset of the Tyrrhenian stretching.

Keywords: Mesozoic-Tertiary, Sicilian Maghrebian Chain, modes of extension, basin formation, normal faults

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