The Plio-Pleistocene evolution of the Crotone Basin (southern Italy): Interplay between sedimentation, tectonics and eustasy in the frame of Calabrian Arc migration

Earth-Science Reviews 115 (2012) 273–303

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The Plio-Pleistocene evolution of the Crotone Basin (southern Italy): Interplay between sedimentation, tectonics and eustasy in the frame of Calabrian Arc migration Massimo Zecchin a,⁎, Mauro Caffau a, Dario Civile a, Salvatore Critelli b, Agata Di Stefano c, Rosanna Maniscalco c, Francesco Muto b, Giovanni Sturiale c, Cesare Roda d a

OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), 34010 Sgonico (TS), Italy Dipartimento di Scienze della Terra, Università della Calabria, 87036 Arcavacata di Rende (CS), Italy Dipartimento di Scienze Geologiche, Università di Catania, 95129 Catania, Italy d Dipartimento di Georisorse e Territorio, Università degli Studi di Udine, 33100 Udine, Italy b c

a r t i c l e

i n f o

Article history: Received 17 March 2012 Accepted 3 October 2012 Available online 1 November 2012 Keywords: Crotone Basin Pliocene–Pleistocene Tectonics and sedimentation Eustasy Calabrian Arc

a b s t r a c t The Crotone Basin is the exposed part of a larger Neogene forearc basin developed in the Ionian Sea in the frame of the SE-ward migration of the Calabrian Arc, which led to the subduction of the Ionian lithosphere and the spreading of the Tyrrhenian back-arc Basin (central Mediterranean). Taking into account the geologic context that accompanied its accumulation, the Plio-Pleistocene part of the Crotone Basin succession is exceptionally well preserved, and consists of a suite of continental, paralic, shallow-marine and deep-marine deposits organized to form unconformity bounded stratal units that in turn compose two main tectono-stratigraphic cycles. The unconformities separating these units are well recognizable along the basin margin and tend to vanish basinwards, and they record phases of basin reorganization linked to large-scale tectonics. In particular, the basin evolution was characterized by a cyclic pattern consisting of an alternation between longer subsidence phases, that favored the accumulation of stratal units, and uplift phases that led to base-level falls and the generation of unconformities. These phases were strictly related to an alternation between active subduction of the Ionian lithosphere below the Calabrian Arc, accompanied by the spreading of the Tyrrhenian back-arc Basin and by extension and subsidence in the forearc basin, and regional-scale compressional and transpressional events, during which the Arc migration temporarily stopped. The younger uplift of the basin, started during middle Pleistocene and still active, was characterized by extensional tectonics, and its interplay with glacio-eustasy controlled the formation of marine terraces. Since the Plio-Pleistocene tectonic episodes affecting the Calabrian Arc during its SE-ward migration seem to be all recorded in the Crotone Basin, the recognition of their effects on the basin fill and their time constraint become both critical, representing a reference to develop a clearer picture on the complex evolution of the central Mediterranean. © 2012 Elsevier B.V. All rights reserved.

Contents 1. 2.

3.

Introduction . . . . . . . . . . . . . . . . . . Geological setting . . . . . . . . . . . . . . . . 2.1. The Calabrian Arc and the Crotone Basin . . 2.2. Stratigraphy of the Crotone Basin . . . . . The Plio-Pleistocene succession of the Crotone Basin 3.1. Cavalieri Marl and Cutro Clay . . . . . . . 3.2. Zinga Group . . . . . . . . . . . . . . . 3.2.1. Zinga Sandstone . . . . . . . . . 3.2.2. Montagnola Clay . . . . . . . . . 3.2.3. Belvedere Formation . . . . . . . 3.2.4. Murgie Sandstone . . . . . . . . 3.3. Spartizzo Clay . . . . . . . . . . . . . .

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⁎ Corresponding author. E-mail address: [email protected] (M. Zecchin). 0012-8252/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.earscirev.2012.10.005

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3.4.

Scandale Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1. Casabona Member . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2. Strongoli Member (Strongoli Tongue) . . . . . . . . . . . . . . . . . 3.4.3. Rocca di Neto Member . . . . . . . . . . . . . . . . . . . . . . . . 3.5. Serra Mulara Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6. San Mauro Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. The Plio-Pleistocene stratigraphic architecture . . . . . . . . . . . . . . . . . . . . . 4.1. Stratal surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1. Zanclean surface (ZS) . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2. Zinga 2 unconformity (Z2U) . . . . . . . . . . . . . . . . . . . . . . 4.1.3. Zinga 3 unconformity (Z3U) . . . . . . . . . . . . . . . . . . . . . . 4.1.4. Timpa Biso unconformity (TBU and TBU′) . . . . . . . . . . . . . . . 4.1.5. Gigliolo unconformity (GLU) . . . . . . . . . . . . . . . . . . . . . 4.1.6. Serra Mulara unconformity (SMU) . . . . . . . . . . . . . . . . . . . 4.1.7. Base of marine to continental terraces (BT1 to BT5) . . . . . . . . . . . 4.2. Unconformity-bounded tectono-stratigraphic cycles and minor stratal units . . . . 4.2.1. Cycle I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2. Cycle II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3. Terraced units . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Sequence stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. The control on the Plio-Pleistocene basin fill: a cyclic evolutionary model for the Crotone Basin 5.1. The Zanclean subsidence phase . . . . . . . . . . . . . . . . . . . . . . . . 5.2. The mid-Pliocene tectonic event . . . . . . . . . . . . . . . . . . . . . . . . 5.3. The Piacenzian subsidence phase . . . . . . . . . . . . . . . . . . . . . . . . 5.4. The early Gelasian tectonic event . . . . . . . . . . . . . . . . . . . . . . . . 5.5. The Gelasian–Calabrian subsidence phase . . . . . . . . . . . . . . . . . . . . 5.6. The mid-Pleistocene tectonic events . . . . . . . . . . . . . . . . . . . . . . 5.7. The Ionian subsidence phase . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8. The regional uplift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.9. The role of eustasy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Introduction The control of tectonics, eustasy, climate and local processes on sedimentation is a complex topic that attracted the interest of several scientists involved in the study of the evolution of sedimentary basins. Historical debates such as the role of eustasy vs. tectonics in shaping depositional sequences are among the best known in the geologic community (see the various contributions in Wilgus et al., 1988; Miall, 1997), and they served to highlight that, though at different degree and scale, all external factors are generally recorded in basin successions. Long-term cyclicity is typically controlled by large-scale tectonics influencing subsidence, although this may interfinger with eustasy of longer periodicity (Cloetingh, 1988; Miall, 1997; Leeder, 2011). In contrast, the smaller-scale cyclicity recognizable in the geologic record is commonly controlled by eustatic and climatic factors as well as by autocyclicity (Einsele et al., 1991), though local tectonics such as that linked to synsedimentary normal faulting may produce a small-scale, relatively short-term cyclicity (Colella, 1988; Dorsey et al., 1997). The discrimination of all factors accompanying the evolution of sedimentary basins, and the determination of their role in shaping sedimentary successions, are not simple issues, and they should require careful integration of multidisciplinary studies taking into account that successions having different characteristics are expected, depending on the type of basin (see Einsele, 2000). Beyond the usefulness in determining the role of different controlling factors to define the evolution of individual basins, the recognition of the imprint of such factors on sedimentary successions may be very helpful also to reconstruct the geodynamic history of larger-scale lithospheric blocks, since phases of plate migration or changes in the tectonic regime due to the interfingering of crustal

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elements have good chance to be recorded by sedimentation (e.g. Einsele, 2000; Patacca and Scandone, 2001; Leeder, 2011). The improvement in detail of both architectural style and dating of events in the succession of sedimentary basins is therefore crucial to achieve these objectives. The present review illustrates the state of art in the knowledge of the Pliocene to Pleistocene part of the succession of the Crotone forearc Basin (southern Italy), the larger exposed Neogene basin in the Calabrian Arc (Fig. 1). The latter is a composite terrane characterized by a complex structure, the comprehension of which is critical to depict the evolution of central Mediterranean. The chosen stratigraphic interval is justified by its exceptional preservation, whereas the older part of the succession is more deformed and disturbed by the Messinian events. The review is mostly focused on an area exceeding 500 km 2, between the northern and southern ends of the Crotone Basin (Figs. 1B,D, 2 and 3), and it was previously investigated by several authors (among others, Ogniben, 1955; Roda, 1964; Aguirre and Pasini, 1985; Gliozzi, 1987; Zecchin et al., 2003, 2004a, b; Capraro et al., 2006; Speranza et al., 2011). Several studies illustrating the succession (late Serravallian to middle Pleistocene) of the Crotone Basin highlighted its complexity due to the interfingering of tectonics and eustasy, with the additional role of climate in shaping stratal units (Van Dijk, 1990; Massari et al., 2002, 2007; Zecchin et al., 2004a,b, 2006). Large-scale tectonics involving the whole Calabrian Arc as well as the Southern Apennines and the Sicilian Maghrebides is thought to be recorded in the succession of the basin, in the form of changes in architectural style of sedimentary units and of unconformities having distinctive signatures (Massari et al., 2002; Zecchin et al., 2006). The complexity of this peculiar context is reinforced by the sum of effects due to the subduction of the Ionian lithosphere beneath the Calabrian Arc, producing

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Fig. 1. (A) Structural map of the Calabrian Arc and location of the Crotone Basin (modified from Van Dijk and Okkes, 1991). Note the NW-trending shear zones that dissect the Calabrian Arc and the main basins located in the Ionian and Tyrrhenian Seas. (B) Simplified geologic map of the Crotone Basin showing the study areas (see Figs. 2 and 3) (modified from Zecchin et al., 2004a). (C) NW-SE section across the Calabrian Arc (see the A–A′ transect in Fig. 1A), showing the main structural elements (modified from Van Dijk, 1992). (D) NNW–SSE section across the Crotone Basin (see the B–B′ transect in Fig. 1B). Note the thickness increase of the Plio-Pleistocene succession toward the south and part of the thrust system located in the modern offshore area. P2 = Perrotta 2 well (see Fig. 6); TC1 = Torre Cannone 1 well (see Fig. 6).

the forearc basin, with those of strike-slip tectonics due to the interference between the Arc and adjacent crustal elements (Malinverno and Ryan, 1986; Knott and Turco, 1991; Bonardi et al., 2001) (Fig. 1A,C). The comprehension of the relations between large-scale tectonics and variations observed in the sedimentary succession, their timing determined on the basis of careful biostratigraphic data, and their distinction from products related to other causes, are therefore crucial to delineate a clearer picture on the complex evolution of the Calabrian Arc. The achievement of such objectives is the aim of the present paper, which consequently could be considered as a tool for any future study dealing with the geodynamic evolution of the central Mediterranean, an issue that is not yet adequately understood. 2. Geological setting 2.1. The Calabrian Arc and the Crotone Basin The geodynamic evolution of the central Mediterranean is the result of complex interactions between collisional processes and extensional tectonics controlled by the Cenozoic convergence between African and Eurasian plates (Dewey et al., 1989). The main tectonic elements generated by these processes since the Neogene are the southern Apennine–Maghrebian chain and the Tyrrhenian back-arc Basin, both linked to the westward subduction of the Adriatic and Ionian lithospheres (Fig. 1A,C). The back-arc extension in the Tyrrhenian area was discontinuous, with migration of the locus of extension with time, and it accompanied the shortening in the Apennine–Maghrebian fold and thrust belt (Malinverno and Ryan, 1986; Finetti et al., 2005a,b). This extension was directed toward the east from Tortonian to early Pliocene, generating the Vavilov sub-basin, and toward the SE during late Pliocene–early Pleistocene, when the Marsili sub-basin opened (Patacca et al., 1990; Sartori, 2003) (Fig. 1A). Episodicity in the Tyrrhenian back-arc extension was attributed to the interference of the retreating oceanic slab

with intervening buoyant continental foreland lithosphere (Apulian and Pelagian blocks), leading to temporary stop or strong slowingdown of the subduction (Argnani and Savelli, 1999; Sartori, 2003). Slab tearing episodes accompanied by lateral flow of the mantle are commonly invoked for the subsequent resumption of the subduction (Faccenna et al., 2004; Chiarabba et al., 2008). In this frame, the Calabrian Arc represents an independent arcuate terrane (the Calabria–Peloritani terrane of Bonardi et al., 2001) that connects the NW-trending southern Apennine chain and the E-trending Sicilian Maghrebides, and separates the Ionian and Tyrrhenian basins (Fig. 1A). It is composed of a pile of pre-Mesozoic polymetamorphic nappes comprising large sheets of an Hercynian crystalline basement (forming the Sila and Aspromonte massifs) and local remnants of a Mesozoic to Cenozoic succession, considered by some authors as a fragment of the Alpine belt overthrusted upon the Triassic–Miocene sedimentary sequence of the Apennine– Maghrebian chain during Miocene (Amodio Morelli et al., 1976). The Calabrian Arc migrated south-eastward from mid-Miocene onwards in response to the subduction of the Ionian oceanic lithosphere along a deep and narrow, W-dipping Benioff zone (Malinverno and Ryan, 1986; Bonardi et al., 2001; Faccenna et al., 2001, 2004; Sartori, 2003; Finetti et al., 2005a). The diachronous collision between the Apennine–Maghrebian chain and the Apulian foreland to the north, and the Pelagian block to the south, coupled with a different velocity of propagation of the thrust front (e.g. Lickorish et al., 1999), produced the arcuate shape exhibited by the Calabrian Arc (Fig. 1A), through both clockwise (Sicily and Calabria) and counter-clockwise (southern Apennines) rotations in a “saloondoor” fashion until early Pleistocene, as testified by paleomagnetic investigations (Rosenbaum et al., 2002; Speranza et al., 2003; Cifelli et al., 2007; Mattei et al., 2007). The movement toward the SE caused a fragmentation of the arc in individual blocks bounded by NW-trending shear zones, which controlled the development of basins located along both the Ionian and Tyrrhenian sides of Calabria (Knott and Turco, 1991; Lentini et al., 1995) (Fig. 1A). These shear

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Fig. 2. Geological map of the eastern part of the study area in the Crotone Basin, showing the Neogene to Quaternary succession of the Crotone Basin, the marine terraces, and the location of measured sections, wells, and of geologic and seismic profiles (modified from Zecchin et al., 2011b).

zones are characterized by left-lateral movement in the central and northern parts of the Arc, and right-lateral movement in the south (Knott and Turco, 1991; Van Dijk, 1991, 1994; Tansi et al., 2007; Del Ben et al., 2008). The northernmost NW-trending shear zone is represented by the Pollino Line, separating the Calabrian Arc from the southern Apennines (Fig. 1A).

The offshore external region of the Calabrian Arc displays a thick and wide accretionary wedge composed of deformed Mesozoic and Cenozoic sediments belonging to the African plate, that shapes with a rugged topography the sea-floor of the Ionian Sea from the Malta to the Apulia escarpments, and is characterized by an active front in the Ionian abyssal plain (Polonia et al., 2011) (Fig. 1A,C). The

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Fig. 3. Geologic map of the north-western part of the study area in the Crotone Basin, showing the location of measured sections (modified from Zecchin et al., 2004a). Sections: CAP 1 = Capone 1; CBS 1 = South Casabona 1; CBS 2 = South Casabona 2; CBSE = South-East Casabona; CBW = West Casabona section; CEL 1 = Cellara 1 section; CEL 2 = Cellara 2 section; CLE = East Calamia; DCE = East Destra Capitano; MNT = Montagnola; MPW = West Montagna Piana; SAL = Salice; SMS = Santa Maria della Scala; TCV = Timpa dei Cavalieri; TCVS = South Timpa dei Cavalieri; ZNE = East Zinga; ZNS = South Zinga; ZVS = South Zinga Vecchia; ZVW = West Zinga Vecchia.

Messinian salinity crisis is inferred to have influenced the evolution of the wedge, as the basal decollement ramps up onto the Messinian salt deposits, producing a fast forward progradation of the frontal thrust and the consequent underplating of the Crustal Ionian sequence during trench rollback (Minelli and Faccenna, 2010). Since middle Pleistocene, the Calabrian Arc experienced rapid uplift of up to ca. 1 mm/yr (Westaway, 1993) that persists today, as documented by flights of marine terraces developed along the coast. Some hypotheses have been proposed to explain this uplift, such as an isostatic rebound that followed the breaking of the subducted Ionian Crust (Spakman, 1986; Westaway, 1993; Wortel and Spakman, 2000) or a convective removal of the deep root and consequent decoupling of the Arc from the subducting plate (Doglioni, 1991; Gvirtzman and Nur, 2001; D'Agostino and Selvaggi, 2004). The uplift was locally accommodated by repeated displacement along the major active faults (Monaco and Tortorici, 2000; Catalano et al., 2003). Along the Ionian side of the Calabrian Arc, the Ionian forearc Basin developed internally with respect to the accretionary wedge since late Oligocene (Cavazza and DeCelles, 1993; Bonardi et al., 2001; Cavazza and Barone, 2010) (Fig. 1A,C). It is composed of some parts presently uplifted and cropping-out along the Ionian coast, such as the Crotone Basin, and of a main active area known to as the Crotone–Spartivento Basin (Fig. 1A,B,C). The Crotone Basin is bounded to the north and to the south by two NW-trending left-lateral shear zones, called Rossano-San Nicola and Petilia-Sosti respectively (Meulenkamp et al., 1986; Van Dijk, 1990, 1991, 1994; Van Dijk and Okkes, 1991), and is currently separated from the Crotone–Spartivento Basin by some thrust fronts (Fig. 1A, B,D). The Crotone Basin began to open between Serravallian and Tortonian times (Roda, 1964; Van Dijk, 1990), and its tectonic history was characterized by a dominant extensional tectonic regime that was interrupted periodically by relatively short compressional or

transpressional phases in mid-Messinian, earliest mid-Pliocene and mid-Pleistocene times (Van Dijk, 1990, 1991; Zecchin et al., 2004a; Massari et al., 2010). Since middle Pleistocene, a main shift from dominant subsiding conditions to generalized uplift led to the emergence of the basin (Gliozzi, 1987; Cosentino et al., 1989; Zecchin et al., 2004b). 2.2. Stratigraphy of the Crotone Basin The succession of the Crotone Basin lies on a crystalline basement, which is characterized by several lithologic components belonging to the Sila Unit (Barone et al., 2008 and references therein) (Figs. 1B and 4), in particular granodiorites, gneisses and phyllites. At the modern marine area in front of Crotone, the basin succession rests on older sedimentary units (Roveri et al., 1992). The oldest unit of the succession is the San Nicola Formation (late Serravallian), that is up to 150 m thick and is dominated in its lower part by roughly stratified conglomerates that pass upward into conglomerates and coarse-grained sandstones (Ogniben, 1955; Roda, 1964; Van Dijk, 1990) (Fig. 4). This unit was interpreted to represent the transition from an alluvial fan to a shallow-marine environment (Van Dijk, 1990; Massari et al., 2010). The local occurrence of carbonate sediments containing Lucina sp. in the upper part of the unit indicates a markedly marine depositional setting (Ogniben, 1955). The San Nicola Formation is overlain by the marly claystones and silty sandstones of the Ponda Clay (Tortonian) (Fig. 4), which locally exceeds 300 m of thickness (Ogniben, 1955; Roda, 1964). This unit is inferred to have accumulated in a relatively deep-marine setting, locally subjected to turbidite deposition (Barone et al., 2008). In the northern part of the basin, near the Strongoli village (Figs. 1B and 2), the Ponda Clay is overlain by an olistostrome up to 200 m thick, called “Varicolored Clays” and characterized by a variegated clayey matrix containing decimeter-scale to meter-scale calcareous,

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Fig. 4. The Serravallian to Ionian succession of the study area, showing the inferred sedimentary environments that range from continental to deep-marine (the Miocene part of the succession is modified from Barone et al., 2008).

arenaceous and pelitic blocks (Ogniben, 1955; Roda, 1964) (Fig. 4). This chaotic body is equivalent to the Sicilide Complex of southern Apennines (Ogniben, 1969; Critelli, 1999; Critelli et al., 2011). The whitish, finely-laminated diatomites of the Tripoli Formation (early Messinian) reach a maximum thickness of 60 m and rest on the Ponda Clay and the olistostrome (Fig. 4). They record a phase of stressed conditions due to water mass stratification, which preceded the Messinian salinity crisis of the Mediterranean (Massari et al., 2010). The Tripoli Formation is overlain by roughly stratified carbonate breccias, forming a package up 40 m thick, and euxinic claystones up to 20 m thick, passing upward into the Lower evaporite Formation (Roda, 1964) (Fig. 4). The latter, also called “Formazione dei Gessi” by Ogniben (1955), is a Messinian unit composed of carbonate breccias

grading into gypsrudites, gypsarenites and sandstones containing abundant gypsum clasts, reaching a thickness of about 100 m (Barone et al., 2007). Lugli et al. (2007) and Barone et al. (2008) included halite deposits, forming diapirs in the northern Crotone Basin (Zecchin et al., 2003), in the Lower evaporite Formation (Fig. 4), whereas Roda (1964) considered the halite within the overlying “Detritico Salina” Formation. The Lower evaporite Formation is truncated at the top by a second olistostrome of “Varicolored Clays”, reaching a thickness of about 70 m, which in turn is overlain by the Messinian “Detritico Salina” Formation (Fig. 4). The latter, up to 300 m thick, is composed of an alternation of gypsrudites, gypsarenites, and gypslutites, locally including breccias of gypsum and of evaporitic limestone. The

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Fig. 5. The Plio-Pleistocene succession of the Crotone Basin from north to south in the study area, compared with the chronostratigraphic scheme currently adopted by the International Commission on Stratigraphy (Gibbard et al., 2010), and the calcareous nannofossil and planktonic foraminifera biostratigraphic schemes and their chronology by Cita (1975), Rio et al. (1990), Lourens et al. (1996) and Raffi et al. (2006). The succession includes unconformable surfaces that are well recognizable near the basin margin and allow to distinguish stratal units, which in turn form two main cycles. The accumulation of Cycle I started during late Messinian. Note that because of the facies variability among the different places in the northern part of the basin, the Serra Piani stratal unit, found only near Timpa Biso (Fig. 2), is directly overlain by the Cutro Clay, as the Spartizzo Clay and the Casabona Member of the Scandale Sandstone are both absent in that location (see text). Formations: Bv = Belvedere Formation; Cv = Carvane Conglomerate; Mn = Montagnola Clay; Mu = Murgie Sandstone; Sc (Ca) = Casabona Member of the Scandale Sandstone; Sc (RN) = Rocca di Neto Member of the Scandale Sandstone; Sc (St) = Strongoli Member of the Scandale Sandstone; Sm = Serra Mulara Formation; Sp = Spartizzo Clay; Zn = Zinga Sandstone. Surfaces: BT1 = base of marine and continental terraces 1; GLU = Gigliolo unconformity; SMU = Serra Mulara unconformity; TBU = Timpa Biso unconformity; UMU = upper Messinian unconformity; Z2U = Zinga 2 unconformity; Z3U = Zinga 3 unconformity; ZS = Zanclean surface.

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turbidity currents, although a noticeable facies variability occurs among the different locations (Massari et al., 2010). The Upper evaporite Formation is erosionally overlain by the late Messinian Carvane Conglomerate (Roda, 1964) (Fig. 4), consisting of a fining-upward continental succession up to 35 m thick, formed by conglomerates, sandstones and minor siltstones and claystones. Conglomerate clasts are composed mostly of sedimentary rocks, whereas plutonic and metamorphic detritus is subordinate (Barone et al., 2008). The Carvane Conglomerate is sharply overlain by the thick Plio-Pleistocene succession of the Crotone Basin (Fig. 4), consisting of a suite of deep-marine, shallow-marine, paralic and continental deposits organized to form both low- and high-frequency cycles controlled by tectonics and eustasy (Van Dijk, 1990; Massari et al., 2002, 2010; Zecchin et al., 2003, 2004a, 2006). This succession is described and discussed in detail in the next Sections. 3. The Plio-Pleistocene succession of the Crotone Basin 3.1. Cavalieri Marl and Cutro Clay

Fig. 6. The Perrotta 2 and Torre Cannone 1 wells, located in the southern part of the Crotone Basin (Fig. 2 for location). Note the apparently continuous Plio-Pleistocene succession, corresponding to the distal parts of the Cavalieri Marl and Cutro Clay (Fig. 5), which overlies the late Messinian deposits. The Plio-Pleistocene fine-grained succession is punctuated by sand layers interpreted as turbidites.

“Detritico Salina” Formation is unconformably overlain by the late Messinian Upper evaporite Formation (Roda, 1964) (Fig. 4), including gypsrudites, gypsarenites, gypslutites, sandstones and claystones. This unit, up to 180 m thick, accumulated in a basin dominated by

These deep-marine units are described together as they form an apparently continuous Plio-Pleistocene succession in the central and southern part of the study area, whereas shallow-marine, coastal and locally continental deposits are commonly interposed between the two units in the northern and north-western locations, close to the basin margin (Figs. 4–6). Despite the apparent continuity of the succession formed by the Cavalieri Marl and the Cutro Clay in the southern Crotone Basin, seismic data show that the two formations are separated by an unconformity (TBU, Section 4.1.4) that is well recognizable at outcrop only near the basin margin (Figs. 5, 7A and 8). Well data do not document the increase of the terrigenous fraction described by Massari et al. (2010) at the boundary between these units, as the succession shows locally abundant sand layers interpreted as turbidites, which exhibit an erratic vertical distribution (Perrotta 2 and Torre Cannone 1 wells, Fig. 6). While in the northern part of the basin the Cavalieri Marl and the Cutro Clay both exhibit a thickness that varies between a few tens to a few hundreds of meters (Fig. 8), they form a composite succession up to 1200 m thick in the Crotone and Isola di Capo Rizzuto areas to the south (Perrotta 2 well, Figs. 1D and 6). Seismic lines and geologic profiles also highlight an overall thickness increase from west to east (Fig. 7A) and a gentle folding in the succession (Figs. 7B and 9). The Torre Cannone 1 well documents that the Cavalieri Marl form most part of the Pliocene succession toward the southern part of the basin (Fig. 6). In contrast, the Cutro Clay is thicker than the Cavalieri Marl to the north (Fig. 8). Marked thickness changes of the Cavalieri Marl in the northern part of the basin were controlled by halokinesis linked to extensional tectonics (Zecchin et al., 2003). The Cavalieri Marl is Zanclean in age (Roda, 1964; Van Dijk, 1990; Zecchin et al., 2003, 2004a) (Figs. 4 and 5), and crops out in the northern part of the basin, north of the Murgie mountain and between the Zinga and Belvedere di Spinello villages (Figs. 2 and 3). The base of the unit coincides with a sharp boundary at the top of the Messinian continental deposits (ZS, Section 4.1.1 and Fig. 5), typically marked by a gravelly lag. The Cavalieri Marl interfingers with the Zinga Sandstone and is overlain by the Belvedere Formation and the Murgie Sandstone near the basin margin (Figs. 2–5). Lateral facies relationships between the Belvedere and Murgie Formations and the Cavalieri Marl are not visible at outcrop. The Cutro Clay (Roda, 1964) is the best represented formation of the basin, exposed discontinuously in the whole study area excepting

Fig. 7. (A) The PAP-4-82 seismic line, located WSW of Crotone (Fig. 2 for location). The surface bounding the base of the Plio-Pleistocene succession (ZS, Fig. 5), that separating the Zanclean deposits from the late Pliocene to Pleistocene deposits (TBU, Fig. 5), and an overall thickness increase of the succession to the east are recognizable. (B) The CZ-369-83 seismic line, located in the southern part of the Crotone Basin (Fig. 2 for location). The surface ZS (Fig. 5) and a gentle folding of the Plio-Pleistocene succession are recognizable.

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Fig. 8. Geologic profiles across the northern part of the Crotone Basin (Fig. 2 for location). Several unconformities separate different lithoformations (Fig. 5), which are locally dissected by normal faults. The accumulation of the Murgie Sandstone was controlled by a normal listric fault that terminates at TBU. The Serra Mulara Formation is the youngest unit of the basin, below marine to continental terraces (Fig. 5). BT1 = base of marine and continental terraces 1; GLU = Gigliolo unconformity; SMU = Serra Mulara unconformity; TBU = Timpa Biso unconformity; Z3U = Zinga 3 unconformity; ZS = Zanclean surface.

the northernmost part (Figs. 2 and 3), and present sampling revealed a Piacenzian to Ionian age (between the MNN16a and the MNN19f Sub-zones of Rio et al., 1990) (Fig. 5). The unit is not younger than early-middle Calabrian (MNN19d Sub-zone) in the northern part of the basin (Fig. 5). As mentioned above, at outcrop the contact of the unit with the underlying Cavalieri Marl is undetectable in the more distal area, whereas it is marked by a coarse-grained lag and local fluvial sedimentation in the Strongoli area (see Section 4.1.4) (Fig. 2). The Cutro Clay interfingers with the Scandale Sandstone in the northern part of the basin (Figs. 2–5). Higher in the succession, the unit passes abruptly into the Serra Mulara Formation north of the Neto river (Figs. 2, 4 and 5), and into the San Mauro Sandstone west of the study area, near the homonymous village (Fig. 1B). The Cavalieri Marl and the Cutro Clay both consist of gray and light brown monotonous claystones and siltstones rich in foraminifera,

calcareous nannofossils and mollusc shells, accumulated at distal shelf to slope depth (Roda, 1964; Zecchin et al., 2003, 2004a; Massari et al., 2010), which occasionally exhibit a faint stratification (Fig. 10A,B). A layering, characterized by dm-scale bands of different color, is locally present. Centimeter- to decimeter-scale sand layers, interpreted as the result of minor turbidite events, are locally abundant, as documented both at outcrop and wells (Fig. 6). The Cutro Clay is characterized by additional features. In particular, sapropels, in the form of laminated claystone beds 0.1 to 3 m thick containing fish remnants, are locally very common, as observed in the Vrica area (Fig. 10A). Laminated diatomites, slump folds and remnants of large cetaceans are also found within the formation (Fig. 10C). Another characteristic of the Cutro Clay is the presence of ash beds, as documented by Colalongo and Pasini (1980) and Massari et al. (2010).

Fig. 9. Geologic profiles across the central and southern part of the Crotone Basin (Fig. 2 for location). The succession is dominated by the fine-grained Cutro Clay, which is capped by younger marine terraces (Figs. 2 and 5). A gentle folding characterizes the Cutro Clay in this part of the basin. BT1-3 = base of marine and continental terraces 1 and 3; GLU = Gigliolo unconformity.

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Fig. 10. (A) The Vrica area near Crotone (on the right), where the Global Stratotype Section and Point (GSSP) of the Pliocene–Pleistocene boundary was defined in the Cutro Clay (Fig. 2 for location). The Cutro marine terrace caps the basin succession in this area. (B) Typical field appearance of the Cutro Clay just to the south of Vrica (Fig. 2 for location). (C) Large cetacean bones found in the Cutro Clay at Vrica (Fig. 2 for location).

The Cutro Clay is also well known because in the relatively continuous succession of the Vrica area, near Crotone (Figs. 2 and 10A), the stratotype of the Calabrian stage (Gignoux, 1910) and the Global Stratotype Section and Point (GSSP) of the Pliocene–Pleistocene boundary (Aguirre and Pasini, 1985) were defined. 3.2. Zinga Group The Zinga Group, of inferred Zanclean age, is composed of four formations (Zinga Sandstone, Montagnola Clay, Belvedere Formation and Murgie Sandstone, Fig. 4) that are present exclusively in the northern and NW parts of the Crotone Basin and have been extensively described by Zecchin et al. (2003, 2004a, 2006) and Zecchin (2005). This major unit corresponds to both the “Molassa di Zinga” and “Molassa delle Murgie” of the previous authors (Ogniben, 1955; Roda, 1964). 3.2.1. Zinga Sandstone The Zinga Sandstone is recognizable on the NW corner of the basin (Fig. 3), and its thickness varies between 0 and 300 m (Fig. 11). It is interpreted as a composite prograding wedge formed by shoreface to deltaic deposits, which gradually to sharply overlies, and locally interfingers with, the Cavalieri Marl (Zecchin et al., 2003, 2004a) (Figs. 4, 5 and 11). The unit rapidly pinches-out basinwards (to the

SE), and is composed of seven high-frequency sequences (sensu Zecchin and Catuneanu, in press; Catuneanu and Zecchin, in press) (Fig. 11). Thin fluvial and tidally-influenced fluvial deposits are locally found in the upper part of the unit, just below the sharp boundary with the Montagnola Clay (Zecchin et al., 2004a) (Fig. 11). The Zinga Sandstone is inferred to be the result of decreasing accommodation and forced regression due to local uplift aided by halokinesis, possibly coupled with eustasy and/or larger-scale tectonics (Zecchin et al., 2003, 2004a). 3.2.2. Montagnola Clay The Montagnola Clay, up to 100 m thick, overlies the Zinga Sandstone, and is limited to the NW corner of the basin (Figs. 3–5). This unit consists of stratified, gray and brown claystones and siltstones that contain an oligotypic fauna assemblage dominated by Cerastoderma edule, and accumulated in a lagoonal environment (Zecchin et al., 2004a). The unit pinches-out to the SE and is erosionally truncated by the overlying Belvedere Formation (Figs. 4, 5 and 12). 3.2.3. Belvedere Formation As seen for the Zinga and Montagnola Formations, this unit crops out along the NW corner of the basin, between the Casabona and Belvedere di Spinello villages (Fig. 3), and its thickness varies between

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Fig. 11. The Zanclean Zinga Sandstone in the Vitravo valley area, in the NW part of the study area (Fig. 3 for location of the measured sections). This shallow-marine unit is composed of some high-frequency sequences and locally interfingers southward with the upper part of the Cavalieri Marl (Fig. 5). Thin fluvial deposits mark Z2U (Zinga 2 unconformity) locally, below the Montagnola Clay (modified from Zecchin et al., 2004a).

50 and 450 m due to synsedimentary normal faulting (Zecchin et al., 2004a, 2006) (Fig. 12). The same unit is present also in the western part of the basin outside from the study area, between Belvedere di Spinello and San Mauro (Fig. 1B). The Belvedere Formation is composed of well cemented, mixed bioclastic and siliciclastic shoreface deposits organized to form vertically-stacked meter-scale cycles (Zecchin et al., 2004a; Zecchin, 2005, 2007a) (Figs. 12 and 13A). Fine-grained lagoonal deposits ca. 25 m thick, sharply overlain by the shoreface deposits, are locally found (Fig. 12). The marked aggradational component is a typical feature of the Formation (Zecchin et al., 2006; Zecchin, 2007b). A prominent angular unconformity (Z3U, Section 4.1.3) is recognizable within the unit, and it is overlain either by an up to 100 m thick succession containing sand waves in its lower half or by the lagoonal deposits (Figs. 12 and 13A). The erosional lower boundary of the Formation truncates the Montagnola Clay to the north and part of the Cavalieri Marl to the south, whereas the upper boundary corresponds to one of the most important unconformities of the Crotone Basin fill (TBU, Figs. 5, 12 and 13). 3.2.4. Murgie Sandstone This unit is present on the northern part of the basin, near the Strongoli village (Fig. 2), and reaches at least 300 m of thickness within a listric normal fault-controlled depocenter (Fig. 13B,C), whereas it is only ca. 3 m thick in the adjacent structural high (Fig. 8). The Murgie sandstone is mostly composed of shoreface sandstones and conglomerates, containing abundant shell beds above an intraformational angular unconformity (Z3U, Fig. 8) (Zecchin et al.,

2006). The unit exhibits a marked aggradational component due to synsedimentary tectonics. The lower boundary of the unit does not crop out within the fault-bounded basin, and such a fault places the unit in lateral contact with the Cavalieri Marl (Figs. 8 and 13B,C). The upper boundary corresponds to the unconformity TBU (Figs. 5 and 13B,C). The recognition of these unconformities suggests that the Murgie Sandstone is in part lateral equivalent to the Belvedere Formation (Figs. 4 and 5), and its lower part possibly correlates with the Montagnola and Zinga Formations. Another unconformity (TBU′, Section 4.1.4), overlain by ca. 20 m thick fluvial, coastal and shallow-marine deposits is present to the east in the uppermost part of the Formation (Zecchin et al., 2006). 3.3. Spartizzo Clay The Spartizzo Clay (Ogniben, 1955; Roda, 1964; Mellere et al., 2005) is exposed between the Casabona and Belvedere di Spinello villages in the northern part of the basin (Fig. 3), and its thickness varies from ca 10 to 150 m due to synsedimentary normal faulting (Figs. 13A and 14). This unit is composed of dark gray and brown layered mudstone containing an oligotypic fauna assemblage dominated by Cerastoderma edule, very similar to that characterizing the Montagnola Clay. In the same way, the unit is thought to represent a lagoonal deposit (Roda, 1964; Mellere et al., 2005). The Spartizzo Clay sharply overlies the Belvedere Formation, and in the Casabona area it interfingers laterally with the shallow-marine deposits of the Scandale Sandstone (Figs. 5, 13A and 14).

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Fig. 12. The late Zanclean Montagnola Clay (lagoon) and Belvedere Formation (mostly shallow-marine), which accumulated within half-graben sub-basins in the NW part of the study area (Fig. 3 for location of the measured sections). All synsedimentary normal faults terminate below the TBU unconformity (Fig. 5) that marks the base of the Piacenzian deposits (modified from Zecchin et al., 2004a). TBU = Timpa Biso unconformity; Z2U = Zinga 2 unconformity; Z3U = Zinga 3 unconformity.

3.4. Scandale Sandstone The Scandale Sandstone (Ogniben, 1955; Roda, 1964; Mellere et al., 2005; Zecchin et al., 2006) is found in the Casabona, Rocca di Neto, Strongoli and Zinga areas (Figs. 1B, 2 and 3), and it is present also to the west, outside from the study area. The unit shows a complex architecture that varies depending on the location. Overall, three members were recognized: Casabona, Strongoli and Rocca di Neto (Fig. 5). 3.4.1. Casabona Member The Casabona Member represents the lower part of the Scandale Sandstone, and consists of shoreface sandstones and conglomerates, forming decameter-scale prograding wedges that interfinger with the Spartizzo Clay at Casabona village (Mellere et al., 2005) (Figs. 5, 13A and 14). The same lateral relationship is recognizable west of Rocca di Neto (Roda, 1965). The uppermost shoreface tongue overlies the Spartizzo Clay and is sharply overlain by a meter- to decameter-scale interval of shelf siltstones, which represent the proximal part of the Cutro Clay (Figs. 5, 13A and 14). The Spartizzo Clay and the Casabona Member of the Scandale Sandstone, therefore, form together a package showing a thickness that varies between 30 and 180 m due to synsedimentary tectonics, which is composed of five transgressive-regressive cycles that testify to a deepening-upward trend during middle to late Piacenzian time (Mellere et al., 2005; Zecchin et al., 2006) (Figs. 5 and 14). Although thinner, the same deepening-upward package is found also north of the Zinga village (Mellere et al., 2005) (Fig. 3).

3.4.2. Strongoli Member (Strongoli Tongue) The Strongoli Member or Tongue was formerly referred to as the Strongoli Sandstone (Ogniben, 1955), consisting of a discontinuous shoreface to inner shelf belt (Capraro et al., 2006) oriented ENE– WSW and prograding to the SSE in the area of the Strongoli village (Fig. 2). This unit is early Gelasian in age (Capraro et al., 2006), and has been considered younger than the Scandale Sandstone (Roda, 1964). Surprisingly, new datings by means of calcareous nannofossils and planktonic foraminifera from deeper-marine mud intercalations revealed that the top of the prominent prograding shoreface wedge that forms the upper part of the Scandale Sandstone in the Casabona area is Gelasian in age, within the Discoaster brouweri Zone (MNN 18, Rio et al., 1990), and correlates with the Strongoli Tongue (Figs. 5, 13A and 14). The Strongoli Tongue is therefore considered here as a member of the Scandale Sandstone (Figs. 5, 13A,B,C and 14). The unit is up to 60 m thick and pinches-out distally, in the Strongoli area, within the Cutro Clay (Figs. 5 and 8). The lower boundary with the Cutro Clay is gradual at Strongoli, however it becomes sharp and erosional in the more proximal part at Casabona (Mellere et al., 2005) (Fig. 13A,B,C). The upper boundary (GLU, Section 4.1.5) is sharp both in the Casabona and Strongoli areas, and testifies to a very rapid transition to slope depth (Figs. 14 and 15A). 3.4.3. Rocca di Neto Member The Rocca di Neto Member is found at the homonymous locality only (Fig. 2), and consists of meter- to decameter-scale shoreface tongues

286 M. Zecchin et al. / Earth-Science Reviews 115 (2012) 273–303 Fig. 13. The major unconformity found in the Crotone Basin (the Timpa Biso unconformity, TBU, Fig. 5), separating the two main Plio-Pleistocene cycles (Cycles I and II, Fig. 5), as it appears in the northern part of the study area. (A) South of the Casabona village (Fig. 3 for location), the activity of a normal fault of uncertain age exposed TBU, which separates the Zanclean Belvedere Formation from the Piacenzian to Gelasian Spartizzo Clay and Scandale Sandstone (Fig. 5). In this location, the Spartizzo, Scandale and Cutro Formations accumulated in the south Casabona half-graben, whose bounding fault dissected the previously deposited Belvedere Formation generating the Casabona horst (see text). Z3U = Zinga 3 unconformity. (B) and (C) In the Timpa Biso area (Fig. 2 for location), TBU separates the Zanclean Cavalieri Marl and Murgie Sandstone from the Piacenzian to Gelasian Cutro Clay and Strongoli Tongue (Fig. 5). Note the fluvial deposits marking TBU locally, and that the same surface seals the fault bounding the Murgie half-graben.

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Fig. 14. Transect between the Casabona and Strongoli villages (Fig. 1B), showing the Piacenzian and Gelasian units and fault-controlled depocenters during the accumulation of the lowermost part of the Gigliolo stratal unit (Fig. 5), and therefore prior to more recent tectonism and erosion. Note the continuity of the Strongoli Tongue in the area and the great thickness of the transgressive succession (between surfaces SU and MFS) near Casabona (modified from Zecchin et al., 2006). GLU = Gigliolo unconformity; TBU = Timpa Biso unconformity; MFS = maximum flooding surface; RS = ravinement surface; RSME = regressive surface of marine erosion; SU = subaerial unconformity.

interfingering with distal shelf to slope mudstones and documenting a local alternation between the uppermost Scandale Sandstone and the Cutro Clay (Fig. 5). Datings by means of calcareous nannofossils from samples collected in the distal mudstones indicate that the top of the Member is late Gelasian in age (MNN19a Sub-zone, following Rio et al., 1990) (Fig. 5). The Rocca di Neto Member is therefore the proximal equivalent of the Cutro Clay and of thin transgressive sandstones that overlies the Strongoli Tongue in the Strongoli area (Figs. 5 and 15A).

3.5. Serra Mulara Formation This unit consists of a conglomerate to sandy and mudstone body elongated for ca. 4 km to the SE, lying west of the Neto river delta (Fig. 2). The lower boundary (SMU, Section 4.1.6) is represented by a broad concave-up erosional surface cutting into the Cutro Clay and overlain by conglomerate strata (Figs. 8, 16 and 17). The upper boundary (BT1, Section 4.1.7) consists of an erosional surface overlain

Fig. 15. Details of two surfaces in the Plio-Pleistocene succession. (A) The Gigliolo unconformity (GLU), marking the top of the early Gelasian Strongoli Tongue (Fig. 5). Note the fining-upward trend of the above succession, testifying a relatively rapid deepening of the basin in the Gelasian (see text). (B) The sharp contact between the late Messinian continental deposits (Carvane Conglomerate) and the Cavalieri Marl, exposed north of Belvedere di Spinello (Fig. 3). The contact (the Zanclean surface, ZS, Fig. 5) is marked by a thin transgressive lag.

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Fig. 16. Panoramic view of the Ionian Serra Mulara canyon fill (i.e. the Serra Mulara Formation, Fig. 5), exposed west of the Neto river mouth (Fig. 2 for location). The Serra Mulara unconformity (SMU, Fig. 5) sharply separates the canyon succession from the underlying Cutro Clay.

by fluvial deposits that are part of the Cutro Terrace (Fig. 17). The succession forming the Serra Mulara Formation is 178 m thick and exhibits an overall fining-upward trend, with a reversal to coarsening-upward only in the upper 15 m (Fig. 17). The unit represents a canyon fill succession composed of density-flow deposits and minor hemipelagites (Zecchin et al., 2011a). The presence of hemipelagites has allowed a micropalaeontologic analysis, which documented a Ionian age, between the MNN19f Sub-zone and the MNN20 Zone (Figs. 5 and 17). These deposits record both high-amplitude glacio-eustatic changes and the onset of the uplift of this part of the Calabrian Arc (Zecchin et al., 2011a). 3.6. San Mauro Sandstone The San Mauro Sandstone is absent in the study area, and it is found only in the western part of the basin, as documented by Roda (1964) and Massari et al. (2002, 2010). The unit (up to ca. 200 m thick) conformably overlies the Cutro Clay, and consists of shelf, shoreface, lagoonal and fluvial deposits organized in transgressive–regressive cycles, which record both glacio-eustasy and synsedimentary transtensional tectonics (Massari et al., 2002, 2010). The unit is late Calabrian to Ionian in age, and possibly records the onset of the uplift of this part of the Calabrian Arc (Massari et al., 2002, 2010). 4. The Plio-Pleistocene stratigraphic architecture The Plio-Pleistocene succession of the Crotone Basin is typified by a complex stratigraphic architecture, consisting of two main, basin scale tectono-stratigraphic cycles (I and II), bounded by major stratal surfaces and composed of a series of minor unconformity-bounded stratal units well recognizable along the basin margin (Fig. 5). Tectono-stratigraphic cycles are related to main phases of basin reorganization (see Section 5), and partially correspond to the main cycles of Roda (1964). 4.1. Stratal surfaces 4.1.1. Zanclean surface (ZS) This surface coincides with the base of the Plio-Pleistocene succession, and consists of a sharp contact between the late Messinian Carvane Conglomerate and the Cavalieri Marl, well recognizable in the northern part of the basin, as well as in wells and seismic data (Figs. 4–8). The surface corresponds to a marked high-amplitude reflector in the available seismic profiles (Fig. 7A,B). As recognized north of the Murgie mountain and west of the Belvedere di Spinello village (Figs. 2 and 3), ZS is locally marked by a few cm-thick pebbly conglomerate that is abruptly overlain by the bathyal mudstones (Fig. 15B). Clasts are composed of limestone and sandstone with minor plutonic rocks, whereas reworked Paleogene nummulith tests were rarely observed. ZS is thought to be related to the early Zanclean re-flooding of the Mediterranean basin that followed the phase of

Messinian salinity crisis (Hsü et al., 1973). The hiatus associated to ZS due to erosional processes and non-deposition is very uncertain. 4.1.2. Zinga 2 unconformity (Z2U) Z2U is well recognizable on the NW corner of the basin only, between Zinga and Belvedere di Spinello (Fig. 3). It bounds the base of fluvial and tidally-influenced fluvial deposits found at the top of the Zinga Sandstone and separates this Formation from the overlying Montagnola Clay where fluvial deposits are absent (Zecchin et al., 2003, 2004a) (Figs. 5, 11 and 12). As both these formations rapidly pinch out to the SE, Z2U merges with the sharp contact between the Cavalieri Marl and the Belvedere Formation in nearby southern locations (Fig. 5). The surface is unrecognizable, becoming conformable, further to the SE (Fig. 5). Z2U is inferred to record subaerial exposure near the basin margin (Zecchin et al., 2003, 2004a). 4.1.3. Zinga 3 unconformity (Z3U) Z3U is well recognizable within both the Belvedere Formation and the Murgie Sandstone, and appears as an intra-formational angular unconformity (Figs. 5, 8, 12 and 13A). As mentioned above, the surface is overlain by a package containing sand waves or by lagoonal deposits in the Belvedere Formation (Fig. 12), and by shell-rich sandstones in the Murgie Sandstone. Direct evidence of subaerial exposure is not found. 4.1.4. Timpa Biso unconformity (TBU and TBU′) TBU is the most prominent unconformity in the Plio-Pleistocene succession of the basin, well recognizable in the field toward the northern and western margins, and it represents the sharp boundary between the Zanclean and Piacenzian units (Figs. 5, 8, 12, 13A,B,C and 14). However, at outcrop and in wells this surface is not found in the central and southern parts of the study area (Fig. 6). In contrast, TBU is well recognizable in seismic lines, and is highlighted by onlap relationships of the reflectors associated to the overlying unit (the PAP-4-82 seismic line, Fig. 7A). The PAP-4-82 seismic line also documents a local broad channelized feature at TBU (Fig. 7A). TBU is not recognizable in the CZ-369-83 seismic line (Fig. 7B), as the Zanclean–Piacenzian boundary is placed very high in the succession in this part of the basin (see the Torre Cannone 1 well, Fig. 6). An unconformity inferred to be related to a tectonic phase responsible for the generation of TBU (see Section 5.2) was recognized in several other locations of the Calabrian Arc as well as in the Crotone– Spartivento Basin (Fig. 1A,C) (Roveri et al., 1992; Del Ben et al., 2008; Praeg et al., 2009). Along the basin margin, TBU consists of an angular unconformity. At Timpa Biso, the surface separates the Cavalieri Marl and the Cutro Clay, and is locally marked by fluvial deposits interposed between the two units (Figs. 13B,C and 18). The base of the Piacenzian marine formations is highlighted by an up to 0.5 m thick shell-rich conglomerate, which in turn is either overlain by 2 to 3 m thick shallow-

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Fig. 17. The Ionian Serra Mulara Formation (Figs. 2 and 5) represents a coarse-grained submarine canyon fill dominated by conglomerates in the lower part and by alternating sandstones and hemipelagic mudstones in the middle to upper part. BT1 (base of marine and continental terraces 1) separates the canyon fill from the landward part of the late Ionian Cutro Terrace. The Serra Mulara Formation documents the onset of regional uplift in this part of the Calabrian Arc (modified from Zecchin et al., 2011a).

marine sandstones grading upward into the Cutro Clay or is blanketed by the latter (Figs. 18 and 19). TBU also marks the top of the Murgie Sandstone, and is well recognizable just near Timpa Biso (Fig. 13B,C). Here, TBU is marked by a coarse-grained shell-rich deposit and coincides in part with the gently inclined eastern flank of the Murgie mountain, where separates the Murgie Sandstone from the overlying Cutro Clay (Figs. 13B,C and 19).

In the same locality, another unconformity, named TBU′ and marked by coarse-grained fluvial deposits, is found in the upper part of the Murgie Sandstone (Fig. 19), and merges with TBU to the west. The interval comprised between TBU′ and TBU consists of the previously mentioned alternation between fluvial, coastal and shallow-marine deposits that characterizes the uppermost part of the Murgie Sandstone southwest of Timpa Biso (the Serra Piani stratal unit,

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Fig. 18. Detailed cross-section showing the fluvial sedimentation found locally in the Timpa Biso area above TBU (Timpa Biso unconformity), which separates main Cycles I and II (Figs. 5 and 13B,C). TBU is overlain by transgressive conglomerates and sandstones (see text). The location is indicated in the larger-scale transect below, which is shown in Fig. 2.

Section 4.2.1 and Fig. 19). In all other locations away from the Timpa Biso-Murgie areas, TBU consists of a sharp contact between the shallow-marine Belvedere Formation and the lagoonal Spartizzo Clay (Figs. 12 and 13A). The feature that probably better characterizes TBU is the sealing of previous structures. In fact, all synsedimentary normal faults controlling the accumulation of the Zanclean deposits (Section 5.2) terminate at this surface (Zecchin et al., 2004a, 2006), as well recognizable in the Casabona and Timpa Biso-Murgie areas (Figs. 12 and 13B,C). Although pedogenesis is not found, the present evidence suggests that both TBU and TBU′ were associated to subaerial exposure along the basin margin. The broad channelized feature recognized in the PAP-4-82 seismic line (Fig. 7A) may resulted either by subaerial processes or by localized submarine erosion like in submarine canyons. The amount of hiatus associated with TBU near the basin margin is uncertain; however, on the basis of the available datings it is estimated in the order of 0.5 Ma (Fig. 5). 4.1.5. Gigliolo unconformity (GLU) This surface marks the top of the Strongoli Tongue, and rapidly disappears basinwards within the Cutro Clay (Figs. 5, 8, 9 and 14). Where is well exposed, GLU is marked by a 0.5 m thick well cemented, shell-rich sandstone bed that overlies a dm-scale interval characterized by Glossifungites ichnofacies (Pemberton et al., 1992) (Fig. 15A). The shell-rich sandstone bed is overlain by a ca. 4 m thick fining-upward interval composed of fine-grained sandstone to siltstone containing shell-beds, which in turn grades upward into

the Cutro Clay (Fig. 15A). Such a succession, that is lateral equivalent to the lowermost part of the Rocca di Neto Member of the Scandale Sandstone, testifies to a rapid deepening from shallow- to deepmarine settings in the MNN18 Zone (Gelasian) (Fig. 5). GLU does not show clear evidence of subaerial exposure. 4.1.6. Serra Mulara unconformity (SMU) SMU is recognizable at Serra Mulara hill, west of the Neto river delta, and separates the Cutro Clay from the overlying Serra Mulara Formation (Figs. 5 and 16). To the south, SMU becomes cryptic within the Cutro Clay passing into a conformity, as it is unrecognizable in seismic lines (Figs. 5 and 7A,B). At Serra Mulara, the surface has a broad channelized shape 1.5 km across, whose axis is oriented NW– SE (Fig. 16). SMU is characterized by a strong lithologic contrast, as it juxtaposes claystones below with conglomerates above (Figs. 16 and 17). This surface is inferred to record one of the more prominent base-level drops during the Plio-Pleistocene, as suggested by the very coarse-grained gravity-flow deposits overlying the unconformity and indicating a closeness of fluvial point sources to the head of the Serra Mulara palaeo-canyon (Zecchin et al., 2011a). Available datings indicate that the hiatus associated with SMU probably exceeds 0.5 Ma at Serra Mulara, whereas it becomes undetectable toward the south (Fig. 5). The hiatus increases where SMU merges with BT1 (see the next section) (Fig. 5). 4.1.7. Base of marine to continental terraces (BT1 to BT5) The base of marine to continental terraces consists of five diachronous surfaces (BT1 to BT5) younger seawards, bounding the

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Fig. 19. Cross-section of the Serra Piani stratal unit, representing the uppermost part of the Murgie Sandstone deposited in the eastern part of the Murgie half-graben, in the Timpa Biso area (Figs. 5 and 13B,C). The unit lies between TBU′ and TBU (Timpa Biso unconformity) and is composed of three continental to shallow-marine high-frequency sequences documenting an overall transgressive trend (see Fig. 18 for symbols). The location is indicated in the larger-scale transect below, which is shown in Fig. 2. Sections are modified from Zecchin et al. (2006).

base of the five terraces of the area (Figs. 2 and 5). They originated as subaerial unconformities due to regional uplift, later reworked by transgressive erosional surfaces linked to glacio-eustatic rises (Zecchin et al., 2004b). The landward part of BT1, which bounds the base of the Cutro Terrace, was not reworked by wave action and maintained its character of subaerial unconformity (Zecchin et al., 2011b) (Figs. 2, 17 and 20). In the northern part of the basin, the Serra Mulara Formation separates BT1 from SMU (Fig. 5). However, in the areas adjacent to the Serra Mulara hill, the sediments of the unit accumulated just after the formation of BT1 (i.e. the Cutro Terrace) directly overlie the Calabrian mudstones of the Cutro Clay, testifying a hiatus of ca. 1 Ma due to the amalgamation of SMU and BT1, which is the longer hiatus found in the Plio-Pleistocene succession (Fig. 5). 4.2. Unconformity-bounded tectono-stratigraphic cycles and minor stratal units 4.2.1. Cycle I The lower boundary of Cycle I is placed at the subaerial unconformity bounding the base of the late Messinian Carvane Conglomerate (the upper Messinian unconformity, UMU, of Massari and Prosser, in press) (Figs. 4 and 5), as it is inferred to record regional uplift related to transpressional tectonics (Barone et al., 2008; Massari et al., 2010). This main cycle is composed of the Carvane Conglomerate and of the Pliocene Zinga 1, Zinga 2, Zinga 3 and Serra Piani stratal units (Zecchin et al., 2004a, 2006), and is bounded at the top by TBU (Fig. 5). Cycle I records a very rapid deepening of the basin

during early Zanclean, as testified by the abrupt superposition of the Cavalieri Marl on the late Messinian continental deposits, followed by a long-term regressive phase characterized by the accumulation of the Zinga Group (Fig. 5). Zecchin et al. (2003) and Zecchin et al. (2004a) placed the base of the Zinga 1 stratal unit at ZS due to its regional extent and easy recognition in the field. The evidence of the onset of halokinesis associated to extensional tectonics in the northern part of the basin just after the formation of ZS (Zecchin et al., 2003) also suggested this choice. The Carvane Conglomerate can therefore be considered the lowermost stratal unit of Cycle I, bounded by UMU below and by ZS above (Fig. 5). The Zinga 1 stratal unit is composed of the Cavalieri Marl and the Zinga Sandstone up to Z2U (Figs. 5 and 11), and its inferred age is early Zanclean. The identification of the unit is strictly linked to the recognition of the upper bounding surface, and therefore it vanishes basinwards (Fig. 5). The attribution of the lower part of the Murgie Sandstone to the Zinga 1 stratal unit is uncertain. The Zinga 2 stratal unit is bounded below by Z2U and above by Z3U, and is composed of the thin fluvial deposits found at the top of the Zinga Sandstone, the Montagnola Clay, the lower part of the Belvedere Formation, and probably of the coeval proximal part of the Cavalieri Marl (Figs. 5 and 12). The recognition of the lower boundary of the unit in the Murgie Sandstone is unclear. Also this unit is unrecognizable basinwards. The Zinga 3 stratal unit corresponds to the upper part of the Belvedere Formation, of the Murgie Sandstone and locally of the Cavalieri Marl, and it is bounded below by Z3U and above by TBU or TBU′ (Figs. 5, 8, 12 and 13A,B,C). The Serra Piani stratal unit, instead,

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Fig. 20. The architecture of the late Ionian Cutro Terrace (MIS 7), the oldest marine to continental terrace of the Crotone area (Fig. 2). The location of the measured sections (numbered) is shown in Fig. 2. The terrace deposits are bounded below by BT1 (base of marine and continental terraces 1), consisting of a composite surface including a ravinement surface passing into a subaerial unconformity landwards, and are composed of two superimposed cycles (modified from Zecchin et al., 2011b).

corresponds to part of the Murgie Sandstone, and is bounded below by TBU′ and above by TBU (Figs. 5 and 19). The unit is found exclusively in the eastern part of the Murgie mountain (Fig. 2). 4.2.2. Cycle II In the northern part of the basin, this main cycle is bounded by TBU below and by SMU or SMU + BT1 above, and is Piacenzian to middle Calabrian in age (Fig. 5). The cycle is composed of the Timpa Biso and Gigliolo stratal units that become indistinguishable basinwards (Fig. 5). Since SMU is absent in the middle to southern part of the basin, in that area Cycle II corresponds to the whole Cutro Clay, Piacenzian to Ionian in age (Fig. 5), and records a long-term phase dominated by deep-marine sedimentation. The Timpa Biso stratal unit, forming the lower part of Cycle II, is bounded below by TBU and above by GLU (Fig. 5). The formations composing the Timpa Biso stratal unit vary depending on the specific location in the northern part of the basin. The unit is composed of the Spartizzo Clay, the Scandale Sandstone (Casabona and Strongoli Members) and the Cutro Clay (Figs. 5, 13A and 14); however the Spartizzo Clay and the Casabona Member are absent in the Strongoli area (to the NE) and are replaced by the open-marine Cutro Clay, which is marked at the base by discontinuous fluvials and thin shallow-marine deposits only partly equivalent to the Spartizzo succession (Figs. 13B,C, 14 and 18). The present facies distribution suggests that proximal settings during deposition were located to the NW (Fig. 14). The age of the Timpa Biso stratal unit is Piacenzian to early Gelasian (Fig. 5). The Gigliolo stratal unit is bounded below by GLU and above by SMU or SMU + BT1, and corresponds to the Gelasian to middle Calabrian part of the Cutro Clay and to the Rocca di Neto Member of the Scandale Sandstone (Fig. 5).

The Ionian Serra Mulara Formation accumulated above SMU and is partially coeval with the youngest part of the Cutro Clay deposited to the south (Figs. 5 and 16), and with the San Mauro Sandstone in the SW area of the basin (Massari et al., 2002, 2010). Although the Serra Mulara Formation is inferred to document a phase of relative sea-level rise following the generation of SMU (Zecchin et al., 2011a), its limited areal extent prevents to clearly define a Cycle III of basinal scale. However, the Formation may be referred to as a stratal unit bounded by SMU and BT1 (Fig. 5). The accumulation of Cutro Clay sediments above SMU in the area adjacent to the Serra Mulara Formation, and of a deltaic system in a paleo-landward position with respect to the canyon (Zecchin et al., 2011a), both later removed by subaerial exposure related to BT1, is inferred (Fig. 5). 4.2.3. Terraced units Marine to continental terraces are bounded at the base by the subsequently younger BT1 to BT5 and at the top by the modern surface of subaerial exposure (Figs. 20 and 21). They represent the younger unconformity-bounded units of the area, deposited during regional uplift from late Ionian time onwards (Zecchin et al., 2004b) (Fig. 5). These units are named (from older to younger) Cutro Terrace, Campolongo Terrace, Capo Cimiti Terrace, Capo Rizzuto Terrace, and Le Castella Terrace, and they are inferred to be related to Marine Isotope Stages (MIS) 7, 5.5, 5.3, 5.1 and 3.3, respectively (Zecchin et al., 2004b) (Figs. 2, 20 and 21). The terrace deposits, typically a few meters thick, are dominated distally by carbonate sedimentation consisting of algal reefs, whereas mixed siliciclastic and bioclastic deposits are present landwards (Zecchin et al., 2004b, 2009, 2011b; Nalin et al., 2007) (Figs. 20 and 21). With the exception of the Cutro Terrace, which shows a lateral

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Fig. 21. The late Pleistocene Capo Cimiti (A) and Le Castella (B) marine terraces exposed at Capo Colonna and Le Castella village, respectively (Fig. 2), and inferred to be related to MIS 5.3 and 3.3. Marine terraces are made of mixed siliciclastic and bioclastic deposits, and are locally composed of superimposed cycles, as shown by the Capo Cimiti Terrace (modified from Zecchin et al., 2010a,b). BT3 = base of marine and continental terraces 3; BT5 = base of marine and continental terraces 5.

transition from marine to continental sedimentation from distal to proximal settings (Fig. 20), the other terraces are fully marine terraces that terminate landward against a coastal cliff (Zecchin et al., 2004b, 2011b) (Fig. 21). 4.3. Sequence stratigraphy The features of the recognized stratal surfaces and of the deposits composing the Plio-Pleistocene succession allow a sequence stratigraphic interpretation for the unconformity-bounded stratal units, following the systematics of Hunt and Tucker (1992) and Helland-Hansen and Gjelberg (1994). Detailed sequence stratigraphic studies of the basin fill and of the terrace deposits were provided by Zecchin et al. (2003, 2004a, 2006, 2009, 2010a,b, 2011b), Mellere et al. (2005), Zecchin (2005, 2007b) and Nalin et al. (2007), and their results are summarized below. In general, lowstand deposits (sensu Hunt and Tucker, 1992) are absent or poorly developed in the sequences recognizable near the margin of the basin (Zecchin et al., 2006; Zecchin, 2007b), whereas they are inferred to be better represented within the distal part of the succession (Fig. 22). Overall, seven depositional sequences were identified (Fig. 22), the duration of which ranges between ca. 0.3 and 1.2 Ma. The Zinga 1 stratal unit shows the features of an incomplete depositional sequence (Sequence 1, Fig. 22), as it is bounded below by ZS that is interpreted as a transgressive wave ravinement surface (WRS) reworking the top of the late Messinian Carvane Conglomerate (Fig. 22). Following this interpretation, the late Messinian fluvial deposits should be included in the sequence, as they are inferred to represent in part a lowstand systems tract (LST) sensu Hunt and

Tucker (1992), bounded below by a subaerial unconformity (SU), and in part a transgressive systems tract (TST) (Fig. 22). The thin conglomerate marking ZS is interpreted as a lag containing material reworked from the substrate, formed after wave ravinement (Demarest and Kraft, 1987; Nummedal and Swift, 1987) (Fig. 15B). The maximum flooding surface (MFS, Posamentier and Allen, 1999), separating the TST from the overlying highstand systems tract (HST), probably coincides or is close to ZS (Fig. 22). The HST is inferred to be formed by the bulk of the Cavalieri Marl, testifying deeper depositional settings (Fig. 22). Forced regression (falling stage systems tract, FSST, Plint and Nummedal, 2000), later culminating in subaerial conditions along the margin (surface Z2U), is recorded by the Zinga Sandstone (Zecchin et al., 2003, 2004a) and by the upper part of the Cavalieri Marl (Figs. 11 and 22). All forced regressive deposits are marked at the base by the basal surface of forced regression (BSFR, Hunt and Tucker, 1992), which is reworked landwards by the diachronous regressive surface of marine erosion (RSME, Plint and Nummedal, 2000) (Figs. 11 and 22). Z2U corresponds therefore to a SU (i.e. the sequence boundary following Hunt and Tucker, 1992) that passes distally into a correlative conformity (CC, Fig. 22). Lowstand or early transgressive deposits are represented by the thin fluvial and tidally-influenced fluvial deposits found occasionally above Z2U (Fig. 11) and forming the lower part of a younger depositional sequence corresponding to the Zinga 2 stratal unit (Sequence 2, Fig. 22). Most part of Z2U is inferred to consist of a SU that meets distally a maximum regressive surface (MRS, Helland-Hansen and Martinsen, 1996), marking the turnaround between regression and transgression (Fig. 22). The lagoonal

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Fig. 22. Wheeler diagram showing interpreted sequence stratigraphic surfaces and systems tracts in the Plio-Pleistocene succession of the Crotone Basin. Sequences are numbered on the right. Codes for unconformities and formations, and the chronostratigraphic scheme are the same shown in Fig. 5. With the exception of the Carvane Conglomerate (Cv), older Messinian and Pleistocene terrace deposits are not interpreted. Surfaces: BSFR = basal surface of forced regression; CC = correlative conformity; MFS = maximum flooding surface; MRS = maximum regressive surface; RSME = regressive surface of marine erosion; SU = subaerial unconformity; WRS = wave ravinement surface. Systems tracts: FSST = falling stage systems tract; HST = highstand systems tract; LST = lowstand systems tract; TST = transgressive systems tract.

Montagnola Clay and the lower part of the shallow-marine Belvedere Formation form together a thick TST, whereas the aggradational part of the Belvedere Formation, below Z3U, represents an aggradational highstand systems tract (AHST, following Zecchin et al., 2006; Zecchin, 2007b) (Fig. 22). The sharp contact between lagoonal and overlying shoreface deposits is a WRS (Fig. 22). The FSST is not found in the Zinga 2 stratal unit. The Zinga 3 stratal unit corresponds to another depositional sequence (Sequence 3, Fig. 22) dominated by the AHST (Zecchin et al., 2006). A relatively thick TST, composed of lagoonal and shoreface deposits, locally overlies Z3U. Thin FSST shoreface deposits, marked below by a RSME passing distally into a BSFR, characterize the upper part of the Zinga 3 stratal unit, just below TBU (Fig. 22). A peculiar sequence architecture is that of the Serra Piani stratal unit, which is composed of three high-frequency sequences organized to form an overall transgressive package overlying TBU′ and truncated at the top by TBU (Figs. 19 and 22). The peculiarity of this architecture is inferred to be related to the accumulation during a main phase of tectonic deformation (see Section 5.2). Although this unit represents an incomplete sequence, due to its very local significance it is not considered in the diagram of Fig. 22. In the Murgie area, TBU′ corresponds to a SU, whereas TBU is interpreted as a WRS marked by a transgressive lag, which reworked a SU developed at the top of the Serra Piani stratal unit (Zecchin et al., 2006) (Figs. 19 and 22).

In the Casabona and Belvedere di Spinello areas, TBU represents a SU (Figs. 13A and 22). The package composed of the Spartizzo Clay and the Casabona Member of the Scandale Sandstone, in the NW part of the basin, form the anomalously thick TST of a depositional sequence (Sequence 4) corresponding to the Timpa Biso stratal unit (Figs. 14 and 22). This TST passes distally into the lowermost part of the Cutro Clay, where the transgressive part is probably much thinner (Fig. 14). The thin fluvial deposits placed below the Cutro Clay in the Timpa Biso area represent either a LST or an early TST, which is overlain by a transgressive lag and shallow-marine deposits passing into the deepermarine mudstones (Fig. 18). The HST is represented by part of the Cutro Clay, whereas the Strongoli Tongue is inferred to represent an episode of forced regression accompanied by an increase of terrigenous supply, as suggested by the sharp lower boundary of the unit, interpreted as a RSME, in the Casabona area (Mellere et al., 2005) (Figs. 14 and 22). The Gigliolo stratal unit is the result of rapid drowning, which is testified by a TST having a thickness that usually is in the order of a few meters only, but it is greater in the Rocca di Neto area (Figs. 15A and 22). The unit corresponds to a depositional sequence (Sequence 5, Fig. 22) largely represented by the HST, whereas FSST and LST deposits are supposed to be present only distally. An interpreted LST to FSST succession is the Serra Mulara canyon fill

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Fig. 23. Evolutionary model for the Plio-Pleistocene succession of the Crotone Basin, and correlation between events in the basin and larger-scale events in the central Mediterranean. Chronostratigraphic and biostratigraphic schemes are the same shown in Fig. 5. Uplifting episodes are well recognizable along the basin margin, where unconformities in the succession are evident, and they correspond to phases in which the Calabrian Arc interferes with adjacent microplates, producing transpression (see text). In contrast, subsiding episodes in the basin correspond to phases of Arc migration and spreading of the Tyrrhenian back-arc Basin. Note that the onset of the younger uplift of the Crotone Basin occurred later with respect to other locations of the Calabrian Arc.

(Zecchin et al., 2011a), which is the younger unit of the basin, placed below the terrace deposits (Fig. 22). The sequence stratigraphic interpretation for the younger and distal part of the basin is only hypothetical, as it is inferred by the known episodes leading to base-level changes in the basin (see Section 5), and by the stratigraphy of the Serra Mulara Formation (Fig. 22). This succession is inferred to be composed of two sequences (Sequences 6 and 7, Fig. 22), the younger of which comprises also the Serra Mulara canyon fill. The marine to continental terrace deposits of the Crotone area show a characteristic sequence stratigraphic architecture, consisting of relatively thin TSTs and thick HSTs + FSSTs, whereas LSTs are absent and probably accumulated further basinwards (Figs. 20 and 21). In some cases, these deposits are characterized by more than one superimposed cycle, reflecting episodes of minor relative sea-level change (Zecchin et al., 2004b, 2009, 2011b; Nalin et al.,

2007) (Figs. 20 and 21). The basal surface of the terrace deposits corresponds to a WRS and locally to a SU (the landward part of the Cutro Terrace) (Figs. 20 and 21). MFSs are commonly found above condensed shell beds, whereas RSMEs bound distally the base of forced regressive deposits (Figs. 20 and 21). Details and controlling processes on the architecture of the terrace deposits were illustrated by Zecchin et al. (2009, 2010a,b, 2011b). 5. The control on the Plio-Pleistocene basin fill: a cyclic evolutionary model for the Crotone Basin The Plio-Pleistocene evolution of the Crotone Basin can be summarized in the alternation between phases characterized by tectonic subsidence (Zanclean, Piacenzian, Gelasian–Calabrian, Ionian) and phases dominated by uplift (mid-Pliocene, early Gelasian, mid-Pleistocene,

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Fig. 24. (A) Section crossing the Zanclean Zinga and Montagna Piana half-graben sub-basins in the NW part of the study area (Fig. 3 for location), and showing geometries and faults active during the deposition of the uppermost part of the Belvedere Formation, prior to the formation of TBU. Note the marked thickness changes due to synsedimentary, listric normal faulting. (B) Cross section parallel and close to the previous one (Fig. 3), showing half-graben sub-basins and horsts developed during Piacenzian time, then sealed by GLU. Note that normal faulting dissected the older Montagna Piana half-graben and TBU, accommodating the deposition of the Spartizzo Clay and the Scandale Sandstone. GLU = Gigliolo unconformity; TBU = Timpa Biso unconformity; Z2U = Zinga 2 unconformity; Z3U = Zinga 3 unconformity; ZS = Zanclean surface.

late Ionian to recent), mostly recognizable toward the basin margin (Fig. 23). Such a cyclic tectonic control was therefore responsible for the creation and destruction of accommodation during the considered time interval, controlling the accumulation of the stratal units and the generation of main unconformities. The peculiar features of these phases, their relation with the basin fill and the unconformities, and the role of eustasy are described below. 5.1. The Zanclean subsidence phase A main phase of tectonic subsidence dominated in the Crotone Basin during the accumulation of the Zanclean Zinga 1, Zinga 2 and Zinga 3 stratal units (Zecchin et al., 2004a) (Fig. 23). This phase followed a Messinian transpressional tectonic event that led to the emergence of the area and the formation of UMU (Barone et al., 2008; Massari et al., 2010) (Fig. 5), followed by the accumulation of the Carvane Conglomerate. Halokinesis, inferred to be associated to extensional tectonics, largely controlled the deposition of the Zinga 1 stratal unit and locally of the Zinga 2 stratal unit, as testified by the growth of salt-cored anticlines leading to significant thickness changes in the Cavalieri Marl and to tectonically enhanced forced regression in the Zinga Sandstone (Zecchin et al., 2003, 2004a) (Fig. 11). Halokinesis initiated only after

the deposition of the Messinian Carvane Conglomerate, as this deposit maintains its thickness and tabular geometry along the flanks of the salt-cored folds (Zecchin et al., 2003). This suggests that the accumulation of the Carvane Conglomerate in the northern part of the basin was probably accompanied by tectonic quiescence, which preceded the extensional tectonics. The accumulation of the Zinga 2 and Zinga 3 stratal units was accompanied by the activity of E- to NE-trending synsedimentary listric normal faults bounding half-graben sub-basins (the Montagna Piana, Belvedere, Murgie, Zinga and Capone half-graben sub-basins; Zecchin et al., 2004a, 2006) in the northern Crotone Basin (Figs. 12, 13B,C, 24A and 25A). Such a normal fault activity determined the observed strong thickness changes in the Belvedere Formation and in the Murgie Sandstone (Figs. 12, 13B,C and 24A). The listric nature of these faults locally shows a shallow horizon of detachment, typically between mostly sandstone deposits of the fault-bounded basin fills and the fine-grained Cavalieri Marl (Figs. 8 and 24A). These faults can be regarded as gravity-driven, detached normal faults, following Schlische (1995). The overall subsiding conditions of the Crotone Basin during this phase are inferred to be linked to an extensional tectonic regime (Zecchin et al., 2004a, 2006; Massari et al., 2010). All synsedimentary normal faults bounding the Zanclean half-graben sub-basins terminate below TBU, separating Cycles I

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Fig. 25. (A) Half-graben sub-basins active during deposition of the Zanclean Zinga 2 and Zinga 3 stratal units (Fig. 5), between Belvedere di Spinello and Strongoli (Figs. 1B, 2 and 3). E- to NE-trending normal faults represent the main structural elements of the area. (B) Half-graben sub-basins active during deposition of the Piacenzian Timpa Biso stratal unit (Fig. 5). Note that the Piacenzian NE-trending synsedimentary normal faults dissected the half-graben sub-basins active during Zanclean time (modified from Zecchin et al., 2006).

and II and representing a time barrier, as shown in the Casabona and Timpa Biso-Murgie areas (Figs. 12 and 13B,C). The origin of Z2U and Z3U, recognizable toward the basin margin in the Zanclean succession, is uncertain, as compression/transpression is not clearly recognized, and normal faulting and halokinesis continued across both surfaces (Zecchin et al., 2004a). Moreover, eustatic drops concomitant to active extensional tectonism might have been involved in the generation of Z2U and Z3U (Zecchin et al., 2003, 2004a, 2006). The Zanclean subsidence phase was in part contemporaneous to the first spreading phase of the Vavilov sub-basin in the Tyrrhenian back-arc area, which is inferred to be initiated ca. 4.3 Ma (Feraud, 1990) (Fig. 23). 5.2. The mid-Pliocene tectonic event A major episode of uplift and basin closure occurred approximately at the Zanclean–Piacenzian boundary, producing TBU plus TBU′ and separating Cycles I and II (Figs. 5 and 23). The onset of the uplift is recorded by the thin forced regressive deposits found at the top of the Belvedere Formation, just below TBU (Zecchin et al., 2004a; Zecchin, 2005) (Fig. 22). This tectonic phase is thought to have had both transpressional and compressional components, and was associated to movements along the main NW-trending shear systems that

cross the Crotone Basin (Van Dijk, 1990, 1991, 1994; Van Dijk and Okkes, 1991; Zecchin et al., 2004a) (Fig. 1B). The southern shear zone seems to be associated to a dextral transpressional component during this phase (Massari et al., 2010), although a long-term overall sinistral displacement is inferred (Van Dijk, 1994). Thin-skinned thrusts active during this phase were observed along the basin margin (Van Dijk, 1991; Van Dijk et al., 2000). Minelli and Faccenna (2010) related the mid-Pliocene uplift of Calabria and the origin of the Crotone–Spartivento slope morphological scarp to crustal thickening, testified by out- of- sequence thrusting and back thrusting (Fig. 26). At a greater scale, this tectonic event is thought to be related to a reorganization of the Calabrian accretionary system linked to the convergence with the Apulian margin (Van Dijk, 1991; Van Dijk and Scheepers, 1995; Doglioni et al., 1996; Gueguen et al., 1998; Sartori, 2003; Praeg et al., 2009). The mid-Pliocene tectonic event terminated the activity of all synsedimentary normal faults characterizing the accumulation of Cycle I and led to a marked basin reorganization (Zecchin et al., 2004a, 2006) (Figs. 12 and 13B,C). The evidence that the fault bounding the Murgie half-graben is sealed by TBU, instead of TBU′ (Figs. 13B,C and 19), suggests that the lower surface records a first pulse related to the transpressional–compressional phase, followed by persisting fault-controlled subsidence in the eastern Murgie

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Fig. 26. Seismic profile showing a thrust system verging to the south and separating the onshore Crotone Basin from the offshore Crotone–Spartivento Basin (see the inset map for location). This succession is only partially known thanks to the information provided by the Leda 1 well.

half-graben, whereas the upper surface probably testifies the acme of the tectonic phase, responsible for the deactivation of the normal faulting (Zecchin et al., 2006).

of the Vavilov sub-basin, which probably ended ca. 2.6 Ma (Feraud, 1990) (Fig. 23). 5.4. The early Gelasian tectonic event

5.3. The Piacenzian subsidence phase After the mid-Pliocene tectonic event, a new phase of tectonic subsidence led initially to generalized transgressive conditions and to the accumulation of the Timpa Biso stratal unit (Figs. 5 and 23). The observed gradual vertical transition from paralic to shallowmarine and then deep-marine deposits (the Spartizzo Clay, the Casabona Member of the Scandale Sandstone and the Cutro Clay, respectively) indicates that basin subsidence was relatively slow (Figs. 5 and 14). During this phase, TBU and the Zanclean sub-basins were dissected by renewed normal fault activity that led to the development of a younger generation of half-graben sub-basins (the south Casabona, Zoiaretto, Cannicelle, Spartizzo and La Lupinata half-graben subbasins; Zecchin et al., 2006) in the northern Crotone Basin (Figs. 13A, 24B and 25B). This synsedimentary normal faulting, leading also to the development of the Casabona horst in the area previously occupied by the Montagna Piana half-graben (Figs. 13A, 24B and 25A,B), strongly controlled architecture and thickness of the Timpa Biso stratal unit (Fig. 14). The Piacenzian NE-trending normal faults exhibit a straighter trend compared to the Zanclean ones, probably due to a deeper detachment horizon, and developed slightly to the SE on average (Fig. 25A,B). Most of these faults stopped their activity approximately at the end of deposition of the Strongoli Tongue, and therefore terminate at GLU (Figs. 14 and 24B). The Piacenzian subsidence phase was contemporaneous to the youngest spreading phase

Toward the northern basin margin, the Piacenzian normal faulting was terminated by another tectonic phase of uncertain nature forming GLU (Figs. 5 and 23). The onset of the tectonic phase is documented by the forced regressive character exhibited by the Strongoli Tongue in its more proximal part (Fig. 22). Due to its limited lateral extent and associated deformation, GLU is inferred to represent minor deformation and uplift along the basin margin, and therefore the tectonic episode responsible for its generation is considered minor in the evolution of the Crotone Basin (Fig. 23). 5.5. The Gelasian–Calabrian subsidence phase This phase was characterized by the accumulation of the Gigliolo stratal unit, which blanketed all the previous structures and testifies to generalized deep-marine marine conditions in the Crotone Basin (Fig. 5), as well as in the Catanzaro and Rossano areas to the south and to the north, respectively. Due to the interposition of the Cirò high north of Strongoli (Barone et al., 2008), where only Miocene deposits crop out, a lateral continuity between the Crotone and Rossano basins during early Pleistocene time is not confirmed. As indicated by the succession overlying GLU, this phase was linked to strong basin collapse and rapid subsidence, the onset of which was dated at 2.3–2.1 Ma (Capraro et al., 2006), coinciding with the age of the opening of the Marsili sub-basin in the Tyrrhenian side of the Calabrian Arc (Nicolosi et al., 2006) (Fig. 23). Toward progressively more southern locations, since the tectonic event

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associated to GLU is not recognizable, a Piacenzian–Calabrian subsidence phase and then a Piacenzian–Ionian subsidence phase controlled the accumulation of the whole Cycle II (Figs. 5 and 23). 5.6. The mid-Pleistocene tectonic events In the northern part of the basin, the relatively tranquil depositional conditions that characterized the Gelasian–Calabrian subsidence phase were drastically interrupted by the onset of another major tectonic event leading to deformation and uplift, which produced SMU and terminated the accumulation of Cycle II toward the basin margin (Figs. 5 and 23). This event was associated to sinistral transpression along the NW-trending Pollino fault system (Fig. 1A), which was the response of continental collision along the southern Apenninic front and consequent differential motion between the Calabrian Arc and the southern Apennines (Patacca et al., 1990; Knott and Turco, 1991; Cinque et al., 1993; Hippolyte et al., 1994; Van Dijk and Scheepers, 1995; Monaco et al., 1998; Patacca and Scandone, 2001) (Fig. 23). Following Speranza et al. (2011), strike-slip tectonics also decoupled the northern Calabrian Arc, which became inactive, from the southern Arc still drifting to the SE. Massari et al. (2002, 2010) described two Pleistocene tectonic events producing unconformities in the western part of the basin, dated ca. 1.2–1.1 Ma and ca. 0.7 Ma. Here, synsedimentary transtension accommodated the sedimentation between the 1.2–1.1 Ma and the 0.7 Ma tectonic events, as testified by the growth structures observed in the San Mauro Sandstone (Massari et al., 2002). In the northern part of the study area, as the Serra Mulara Formation is Ionian in age, and overlies the Cutro Clay that here is not younger than middle Calabrian, it is inferred that SMU is the result of the combined effect of both the 1.2–1.1 Ma and the 0.7 Ma tectonic events (Figs. 5 and 23). As suggested by the duration of the hiatus associated to SMU (Fig. 5), conditions of prolonged subaerial exposure possibly occurred in the northernmost part of the basin between late Calabrian and early Ionian. Although the effects of these tectonic phases tend to vanish toward the center of the basin, they were probably responsible for the generation of the gentle folding recognized in the Cavalieri–Cutro succession in the southern part of the basin (Figs. 7B and 9). On the basis of paleomagnetic data, a post-1.2 Ma strike-slip activity for the NW-trending faults in the Crotone Basin, associated to block rotations, was documented by Speranza et al. (2011), and this was very probably associated to the mid-Pleistocene tectonics events. In particular, Speranza et al. (2011) showed that the northern part and the middle to southern part of the basin belonged to distinct blocks behaving in a different way during this phase, and this may justify the observed variability between the northern and the southern sectors as well as the disappearance of SMU to the south (Fig. 5). 5.7. The Ionian subsidence phase A return to generalized subsiding conditions in the northern part of the basin is inferred to have occurred after the 0.7 Ma event, accompanying the accumulation of the lower to middle part of the Serra Mulara Formation and probably of coeval fine-grained slope deposits and of a deltaic system feeding the canyon succession in adjacent areas (Figs. 5 and 23). This phase was contemporaneous to renewed spreading of the Marsili sub-basin, accompanied by the rise of the Marsili volcano (Nicolosi et al., 2006) (Fig. 23). The timing of the activity of E- and NW-trending normal faults that dissect the Cutro Clay and older formations in the northern part of the basin (Figs. 2 and 8) is uncertain. The present evidence prevents to suppose their synsedimentary activity determining abrupt thickness changes in the Cutro Clay. NW-trending normal

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faults, which locally show a vertical displacement in the order of some hundreds of meters, might have derived from the reactivation of strike-slip faults associated to the Rossano-San Nicola shear zone during the Ionian phase (Fig. 1B), as they seem to have been active after 1.2 Ma (Speranza et al., 2011). 5.8. The regional uplift The recent uplift of the Crotone area was characterized by an extensional tectonic regime, highlighted by the activation of ENE- and NNE-trending normal faults dissecting the marine terraces and older units (Cosentino et al., 1989; Zecchin et al., 2004b) (Fig. 2). Normal faulting modifies significantly the local rate of uplift. The development of marine terraces accompanied the uplift of the basin, the onset of which is clearly recorded only in the succession of the Serra Mulara canyon fill (Fig. 17). Considering the whole Calabrian Arc, the onset of the uplift was diachronous, as it has been dated approximately near the end of early Pleistocene in some areas (Westaway, 1993; Westaway and Bridgland, 2007), and later in the Crotone area (Fig. 23). In particular, Zecchin et al. (2011a) estimated that the beginning of the uplift of the Crotone Basin occurred between 0.4 and 0.45 Ma, that is between Marine Isotope Stage (MIS) 12 and 11 (Figs. 17 and 23). This estimate, based on data collected in the Serra Mulara canyon fill (Fig. 17), takes into account the time necessary to raise upper slope deposits at sea level assuming an uplift rate of 1 m/ka, which is close to the calculated long-term uplift rate since MIS 7 (Zecchin et al., 2004b). We therefore disagree with Massari et al. (2010), who suggested an onset of the uplift after MIS 9–8, as middle Pleistocene deep-marine deposits forming the basement of the MIS 7 marine and continental terrace (i.e. the Cutro Terrace, Figs. 2 and 20) would have had too little time to be raised, exposed and then transgressed. The relatively later uplift of the Crotone area, with respect to the rest of the Calabrian Arc, was possibly linked to an eastward tilting of the eastern flank of the Sila Massif facing the Crotone Basin (Fig. 1B) since middle Pleistocene (Reitz et al., 2010), which may have favored persisting subsidence in the basin until 0.4–0.45 Ma. 5.9. The role of eustasy Recent studies documented that glacio-eustatic changes, accompanied by climate variations, are recorded in the Plio-Pleistocene succession of the Crotone Basin. Zecchin (2005) illustrated a meter- to decameter-scale cyclicity in the shallow-marine Belvedere Formation (Fig. 12), inferred to be linked to Milankovitch processes. An interplay between tectonics, glacio-eustasy and climate was also shown by Massari et al. (2002, 2007) in the San Mauro Sandstone accumulated in the San Mauro sub-basin. A spectacular relationship between glacio-eustasy and the late Ionian to recent regional uplift of the study area is that exhibited by the marine terraces, which record the eustatic peaks related to MIS 7 to MIS 3 and minor sea-level pulses (Zecchin et al., 2004b, 2009, 2010a,b, 2011b; Nalin et al., 2007) (Figs. 20 and 21). Moreover, the prominent interglacial of MIS 11 is recorded in the succession of the Serra Mulara canyon fill (Zecchin et al., 2011a) (Fig. 17). Although glacio-eustatic sea-level changes are very apparent in the succession of the basin, the evidence is that the generation of the major unconformities and the main control on accumulation of the stratal units and of the major cycles were linked to changes in the tectonic style (Fig. 23), with the exception of the terraced units that reflect an interplay between tectonics and glacio-eustasy. Eustasy becomes dominant in shaping the small-scale cyclicity recognizable within the stratal units (Zecchin, 2005). Tectonics, reflecting the main geodynamic changes of the Calabrian Arc, is therefore the principal control on the Plio-Pleistocene sedimentary succession.

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6. Discussion The available data indicate that the depositional history of the Plio-Pleistocene succession of the Crotone Basin reflects changes in the tectonic regime that led to alternating phases of deposition and erosion, determining a cyclic-style basin evolution (Figs. 5 and 23). A similar style of evolution for the whole late Serravallian to Pleistocene succession may be deduced by early studies by Roda (1964), later mostly supported by Van Dijk (1990), and is very apparent in more recent results by Zecchin et al. (2004a, 2006) for the Pliocene succession, and by Massari and Prosser (in press). In contrast, Reitz and Seeber (2012) proposed that a deep-rooted contractional event occurred throughout the Pliocene. The clearest expression of tectonic regime with compressional component in the Crotone Basin succession is represented by the main unconformities. Van Dijk (1990, 1991), Zecchin et al. (2004a) and Zecchin et al. (2006) already highlighted that during the Plio-Pleistocene interval, episodes characterized by compressional and transpressional tectonics abruptly interrupted generally longer phases dominated by basin subsidence and normal faulting. As said above, these tectonic episodes with compressional component reflected main phases of reorganization of the Calabrian Arc (Fig. 23), accompanied by strike-slip movements along the NWtrending shear systems that bound and cross-cut the entire terrane, mostly during mid-Pliocene and mid-Pleistocene times (Patacca et al., 1990; Knott and Turco, 1991; Van Dijk, 1991; Cinque et al., 1993; Hippolyte et al., 1994; Van Dijk and Scheepers, 1995; Gueguen et al., 1998; Monaco et al., 1998; Patacca and Scandone, 2001; Sartori, 2003; Tansi et al., 2007). It is relevant to note that some of the main events recognizable in the Crotone Basin were also documented elsewhere in the Calabrian Arc as well as in the offshore Crotone-Spartivento Basin (Bonardi et al., 2001; Praeg et al., 2009). In contrast to the continuity of TBU in the whole Crotone Basin (Figs. 5 and 7A), the disappearance of SMU in the southern part of the study area probably reflects the fragmentation of the basin in independent blocks experiencing different rotations since 1.2 Ma (Speranza et al., 2011), corresponding to the onset of the midPleistocene tectonic event (Fig. 23). However, the presence of TBU and GLU indicates that transpression related to the activity of the main NW-trending shear systems was effective at least since mid-Pliocene (Fig. 23). The phases of tectonic subsidence that controlled the accumulation within the basin during the Plio-Pleistocene time interval were related to the overall subsiding conditions that characterized the Ionian forearc Basin during this period. Extension in this part of the Calabrian Arc is thought to be linked to phases of active subduction accompanied by back-arc spreading in the Tyrrhenian Sea and consequent opening of the Vavilov and Marsili sub-basins during Pliocene and Pleistocene time, respectively (Sartori, 2003; Nicolosi et al., 2006) (Figs. 1A and 23). Recent data have indicated that back-arc spreading of the Tyrrhenian Sea was episodic (Nicolosi et al., 2006; Guillaume et al., 2010), and generally it correlates with the main subsidence phases recorded in the Crotone Basin (Fig. 23). In particular, the main, very rapid spreading of the Marsili sub-basin occurred between ca. 2.1 and 1.6 Ma, whereas a secondary phase started after 0.78 Ma (Nicolosi et al., 2006), that is after the mid-Pleistocene tectonic events recorded in the Crotone Basin (Fig. 23). The main spreading of the Marsili sub-basin was also associated to the clockwise rotation of the Arc as a rigid microplate (Mattei et al., 2007) (Fig. 23), and probably this event marked the decoupling of the Calabrian Arc with respect to the southern Apennines. On the basis of 39Ar\ 40Ar datings of basalts, the spreading of the Vavilov sub-basin is inferred to have occurred approximately between 4.3 and 2.6 Ma (Feraud, 1990; Guillaume et al., 2010), from Zanclean to late Piacenzian time (Fig. 23). In contrast to that recorded

in the Calabrian Arc basins, evidence of the mid-Pliocene tectonic event is not really apparent in the Tyrrhenian Sea, although the determined age of 3.5 to 3.7 Ma for the basalt-sediment contact in the Vavilov ODP 651 Site (Kastens and Mascle, 1990) might indicate a local spreading stop related to the onset of the tectonic event. The tectonic events with compressional component, therefore, generally corresponded to periods in which the migration temporarily stopped and the Arc segments underwent block rotations and transpression along the NW-trending shear systems (Fig. 23). Despite its minor evidence in the Crotone Basin as well as in other locations of the Calabrian Arc, the early Gelasian tectonic event might represent a large-scale episode as it just separated the Vavilov and Marsili spreading phases (Fig. 23). The thickness increase of the Plio-Pleistocene succession of the Crotone Basin to the SE, documented by wells and seismic lines (Figs. 1D, 6 and 7), is probably due to an increase in the subsidence rate in the same direction. The observed different thickness trends of the Zanclean Cavalieri Marl and of the Piacenzian to Ionian Cutro Clay, showing an increase and a decrease toward the south, respectively (Figs. 1D, 6 and 8), may be due to the basin reorganization occurred during the mid-Pliocene tectonic event, which changed basin depocenters, local physiography and supply directions. With the exception of TBU, the distal succession in the middle to southern part of the basin testifies to relatively tranquil depositional conditions and relatively minor deformation (Figs. 5 and 23). Such a modest tectonic disturbance and relative stratigraphic continuity justifies the choice of the Crotone area for defining stratotypes. However, the relatively continuous succession of the southern part of the basin contrasts with the situation observed just offshore of the present coastline, where a main seaward verging thrust system, locally crossed by strike-slip structures, shapes the modern shelf margin (Figs. 1A,D and 26). Although the thrusting episode was generated during the mid-Pliocene tectonic event (Minelli and Faccenna, 2010), the evidence that the main thrust seems to intersect locally the sea bottom (Fig. 26) suggests a recent reactivation, probably in part related to the mid-Pleistocene tectonics events. Such a thrust system, therefore, separates the onshore, uplifted Crotone Basin from the Crotone-Spartivento Basin that represents the modern forearc area associated to the Calabrian accretionary wedge (Fig. 1A,C). Results from the Crotone Basin, therefore, highlight the effectiveness of basin-scale stratigraphic architecture in documenting larger-scale tectonic events and their relationships with sedimentation. Phases of rapid subduction of the Ionian lithosphere with consequent migration of the Calabrian Arc toward the SE and associated spreading of the Tyrrhenian basins, as well as episodes reflecting transpression due to interferences with adjacent microplates, are all recoded in the Crotone Basin succession, particularly along the basin margins that appear very sensitive to changes in the tectonic regime (Fig. 23). Further research is needed to better relate the timing of migration phases of the Arc and associated spreading in the back-arc area to the alternating episodes of subsidence and uplift recorded in the Crotone Basin, which are now temporally well constrained by detailed biostratigraphic analysis, and therefore represent a reference to be considered for future studies. Similar relationships between stratigraphy and large-scale tectonics were well documented also elsewhere, for example in the Jurassic Sverdrup Basin, arctic Canada (Embry, 1993), in the Miocene Suez Rift (Jackson et al., 2005) and in other extensional basins (Gawthorpe et al., 1994; Martins-Neto and Catuneanu, 2010). The stratigraphy of rift basins may be very complex due to the strong lateral variability of fault-related subsidence and uplift (Ravnås and Steel, 1998). Long-term tectonic control is also documented in the sedimentary succession of large foreland basins such as the Mesozoic Western Interior Seaway of North America (Leckie and Smith, 1992; Gardner, 1995), the South Pyrenean foreland basin, Spain (Marzo et al., 1998), and the Po plain basin, northern Italy (Kent et al., 2002). The

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recognition of a hierarchy of basin-scale unconformity-bounded stratal units, and their analysis from a sequence stratigraphic point of view, is therefore critical in reconstructing the depositional and tectonic history of a tectonically-active basin, and ultimately represents a very powerful tool aiding to depict the geodynamic evolution of crustal elements. 7. Conclusions The current knowledge on the Plio-Pleistocene succession of the Crotone Basin, an onshore uplifted part of a larger Neogene forearc basin developed along the Ionian side of the Calabrian Arc, allows to make the following considerations: – This well preserved basin fill records all tectonic phases accompanying the SE-ward migration of the Calabrian Arc. The PlioPleistocene evolution of the basin can be summarized in the alternation between phases characterized by tectonic subsidence (Zanclean, Piacenzian, Gelasian–Calabrian, Ionian) and phases dominated by uplift (mid-Pliocene, early Gelasian, mid-Pleistocene, late Ionian to recent), defining a cyclic pattern of tectonic control. Tectonics is the main factor controlling the stratal units forming the basin fill, although eustasy is generally well recognizable in the succession. – Phases of marked subsidence in the Crotone Basin were characterized by the accumulation of thick coastal to deep-marine deposits and by the local development of normal fault-controlled subbasins. These phases corresponded to periods of active subduction of the Ionian lithosphere below the Arc and spreading of the Tyrrhenian back-arc Basin, accompanied by a generalized extensional tectonic regime in the forearc area. – Phases of uplift producing unconformities in the Crotone Basin succession, as well as in other locations of the Calabrian Arc and of the Ionian forearc Basin, corresponded to regional-scale compressional and transpressional events, during which the migration temporarily stopped and the segments composing the Arc underwent transpression along NW-trending shear zones. These events are thought to be related to the interference between the Arc and adjacent microplates. – The uplifting phase affecting the Calabrian Arc since latest early Pleistocene was diachronous and accompanied by an extensional tectonic regime, and its onset was delayed for the Crotone area, between 0.45 and 0.4 Ma in the late Ionian. The interplay between uplift and glacio-eustasy led to the formation of a staircase of marine terraces starting from MIS 7. Present results, therefore, demonstrate the effectiveness of the study of basin-scale stratigraphic architecture to define the controls on sedimentation and basin evolution, as well as to reconstruct the evolution of larger-scale crustal elements. In particular, since the alternation between phases of subsidence and uplift in the basin are now temporally well constrained thanks to detailed biostratigraphy, and their significance was understood, these data represent a precious reference aiding to better constrain the complex geodynamic evolution of the Calabrian Arc and in a larger scale of the central Mediterranean, which was characterized by the subduction of the Ionian and Adriatic lithospheres below the Apennine–Maghrebian chain and by the consequent opening of the Tyrrhenian Basin. Acknowledgments This paper is dedicated to Prof. Cesare Roda, who died recently. Prof. Roda has been a pioneering researcher in the Crotone Basin, and we thank him for his contribution and leadership. This research is the result of studies carried out within the CARG Project (official geological cartography of Italy, scale 1:50,000) for the geological mapping of the Ionian Calabria (Resp. C. Roda), the MIUR-ex 60%

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Projects (Palaeogeographic and Palaeotectonic Evolution of the Circum-Mediterranean Orogenic Belts, 2001–2005; and Relationships between Tectonic Accretion, Volcanism and Clastic Sedimentation within the Circum-Mediterranean Orogenic Belts, 2006–2011; Resp. S. Critelli), the 2006–2008 MIUR-PRIN Project 2006.04.8397 ‘The Cenozoic clastic sedimentation within the Circum-Mediterranean orogenic belts: implications for palaeogeographic and palaeotectonic evolution’ (Resp. S. Critelli), and the OGS funded projects WGDT (Morphology and Architecture of the Western Portions of the Gulf of Taranto: a Study of Submarine Instability in a Tectonically Active Margin; Resp. S. Critelli). Well and seismic data shown in this paper (Perrotta 2, Torre Cannone 1 and Leda 1 wells, and PAP-4-82, CZ-369-83 and F75-66 seismic lines) are available online at http:// www.videpi.com (Visibilità Dati Esplorazione Petrolifera in Italia, VIDEPI Project). The authors thank Domenico Chiarella, the Editor Andrew D. 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