Rend. Online Soc. Geol. It., Vol. 21 (2012), pp. 919-920, 2 figs. © Società Geologica Italiana, Roma 2012 919 Key words: Calabrian Arc, Catanzaro Strait, detrital modes, mixed sediments, tidal dunes. INTRODUCTION The Plio-Pleistocene infill of the Catanzaro Basin (central Calabria) includes a Lower Pleistocene (Calabrian), ~80 m thick interval made up of mixed (bioclastic-siliciclastic) sand-sized sediments. The Catanzaro palaeo-strait (Fig. 1) is interpreted as an E-W-elongated, narrow linear basin linked the Ionian and Tyrrhenian seas, producing a marine seaway or strait which was tidally-dominated during the Lower Pleistocene. Two main fault systems bound the basin: an ENE-WSW to WNW-ESE-trending system to the North and an E-W-trending system to the South, both showing an en-échelon-type pattern (TANSI et alii, 2007). The Plio-Pleistocene infill of the Catanzaro Basin unconformably overlies the Upper Miocene conglomerates and evaporites and, locally, the Paleozoic crystalline basement. From the bottom to the top, the Catanzaro Basin infill consists of a Pliocene unit (about 100 m thick) made up of limestone and marls, and erosively overlain by the mixed succession focus of this work. This succession is top-truncated by Quaternary terraced deposits and/or by surfaces of modern exposure (CHIARELLA, 2011). Mixed deposits of the Catanzaro Strait consist of a series of vertically-stacked bidirectional cross strata (Fig. 2) which exhibit a sedimentary facies association typical of tidal dominated environments, including herringbones, bundles and re-activation surfaces (e.g., LONGHITANO et alii, 2012a, b). AIMS and METHODS In this paper, we present the preliminary results of a stratigraphic and sedimentological study carried out with the aim of: (i) outline the hydrodynamic features of the Catanzaro palaeo- strait depicted from the observation of its mixed deposits, and (ii) unravelling provenance from siliciclastic and bioclastic fractions. The techniques adopted consisted on facies analysis and vertical logging of exposed sections and quantitative petrographic analyses performed by point counting on 16 thin-sectioned sand samples. RESULTS The Catanzaro mixed succession has been divided into two units, the lowermost Vena di Maida Unit, and the uppermost Pianopoli Unit both consisting of siliciclastic-bioclastic sandstones. The distinctive elements that allow us to distinguish these two units is the internal strata organisation: (i) the ~30 m thick Vena di Maida Unit consists of vertically-stacked trough cross-strata with 3D internal geometry, whereas (ii) the ~50 m thick Pianopoli Unit is composed of planar 2D cross-strata, passing up-ward to mostly bioturbated mudstones. Data interpretation and preliminary conclusions Cross strata observed in the two units indicate the existence of large dune fields, whose migration was arguably induced by strong tidal currents enhanced by a tidal oceanography. This is confirmed by the diffuse bi-directionality of cross strata mostly parallel to the main strait axis, and by the occurrence of associated tidal structures. The different architectures observed between the Vena di DOMENICO CHIARELLA (†), SERGIO G. LONGHITANO (*) & FRANCESCO MUTO (°) Sedimentary features of the Lower Pleistocene mixed siliciclastic-bioclastic tidal deposits of the Catanzaro Strait (Calabrian Arc, south Italy) Fig. 1 – Simplified geological map of the central Calabrian Arc (modified from Van Dijk et alii, 2000 and TANSI et alii, 2007) _________________________ (†) Weatherford Petroleum Consultants AS - Folke Bernadottes vei 38 - 5147 Bergen, Norway; e-mail: domenico.chiarella@wftpc.com (*) Università degli Studi della Basilicata, Dipartimento di Scienze Geologiche, Viale dell’Ateneo lucano, 10 – 85100 Potenza (°) Università degli Studi della Calabria, Dipartimento di Scienze della Terra, Via. P. Bucci, Arcavacata di Rende – Cosenza.