Alluvial terraces on the Ionian coast of northern Calabria, southern Italy: Implications for tectonic and sea level controls

Geomorphology 106 (2009) 165–179

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Geomorphology j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / g e o m o r p h

Review

Alluvial terraces on the Ionian coast of northern Calabria, southern Italy: Implications for tectonic and sea level controls Gaetano Robustelli a,⁎, Federica Lucà a, Fabio Corbi b, Teresa Pelle a, Francesco Dramis b, Giandomenico Fubelli b, Fabio Scarciglia a, Francesco Muto a, Domenico Cugliari a a b

Earth Science Department, University of Calabria, Via P. Bucci — cubo 15B, 87036 Arcavacata di Rende (CS), Italy Department of Geological Sciences, “Roma Tre” University, Largo S. Leonardo Murialdo 1, 00146 Rome, Italy

a r t i c l e

i n f o

Article history: Received 11 September 2008 Received in revised form 19 December 2008 Accepted 22 December 2008 Available online 1 January 2009 Keywords: Alluvial terraces Morphostratigraphic correlations Sedimentary environment Soil development Tectonics Sea level change Northern Calabria

a b s t r a c t In this paper we present the results of an integrated geomorphological, pedological and stratigraphical study carried out along the Ionian coast of northern Calabria (southern Italy). This area is characterised by the occurrence of five orders of alluvial terraces that are striking features of the landscape, where large and steep catchments debouch from the mountain front to the hilly coastal belt. Field investigations indicate that the deposits of all five terraces are suggestive of shallow gravel-bed braided streams. On the basis of the age of the Pleistocene substratum and morphostratigraphic correlation with marine terraces cropping out in the nearby areas, each order has been associated to specific marine oxygen isotope stages. Consequently, we focused on the interplay of allocyclic factors influencing stream aggradation/degradation. Soil features and other climatic proxies suggest that climate didn't play an important role with respect to tectonic and base-level changes in controlling fluvial dynamics. In particular, we recognised that during the middle Pleistocene the study area experienced a period of subaerial landscape modelling, as suggested by the thick and complex alluvial sequence of the highest terrace (T1). The onset of regional uplift marks a change in the geomorphic scenario, with tectonic and eustatically driven changes in base-level working together in causing switches in fluvial aggradational/erosional phases (T2–T5 terraces). Because of the uplift, river dissection occurred during phases of sea level fall, whereas aggradation phases occurred during periods of climate amelioration (sea level rise) just before highstands were attained. As a consequence, the stepped terraces in the study area reflect the interplay between tectonics (uplift) and sea level changes, in which terraces define episodes of relative sea level fall during the late Quaternary. © 2009 Elsevier B.V. All rights reserved.

Contents 1. 2. 3. 4.

Introduction . . . . . . . . . . . . . . . . . . . . . Geological setting . . . . . . . . . . . . . . . . . . Methods . . . . . . . . . . . . . . . . . . . . . . . Geology and geomorphology . . . . . . . . . . . . . 4.1. The alluvial terraces . . . . . . . . . . . . . . 4.1.1. The Bucida terrace . . . . . . . . . . . 4.1.2. The Armania terrace . . . . . . . . . . 4.1.3. The Malvitano terrace staircase (T3–T5) 4.2. Alluvial depositional environment . . . . . . . 4.3. Pedogenic indices . . . . . . . . . . . . . . . 5. Discussion . . . . . . . . . . . . . . . . . . . . . . 6. Concluding remarks . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . .

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⁎ Corresponding author. Tel.: +39 0984 493546; fax: +39 0984 493601. E-mail address: [email protected] (G. Robustelli). 0169-555X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.geomorph.2008.12.010

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1. Introduction The Quaternary evolution of the Ionian coast of Calabria (southern Italy) has been mainly detected through the analysis of marine terrace staircases aiming to point out their connection with glacio-eustatic sea level changes and evaluating uplift rates (Gliozzi, 1987; Cosentino et al., 1989; Palmentola et al., 1990; Amato et al., 1997; Cucci and Cinti, 1998; Carobene, 2003; Zecchin et al., 2004). Less developed are the studies regarding the geomorphological evolution of Calabria through the analysis of alluvial terraces, notwithstanding their widespread occurrence in the lower reaches of river catchments. In fact, very little is known about correlations between continental and marine morphostratigraphic records, which could be very helpful for the reconstruction and interpretation of morphoevolutive stages of landscape. These issues are addressed in our study of the coastal hilly belt between the Colognati and Trionto River catchments, where several alluvial terraces and nonmarine landforms are present. An alluvial terrace staircase may provide field evidence for studies of long-term evolution of river catchments; a fluvial terrace records the former bed level of a river and can be classified as either aggradational (fill) or degradational (fill-cut or strath) (e.g., Bull, 1990). The switch between aggradation and degradation behaviour of the rivers occurs in response to allocyclic mechanisms (such as climate, tectonics and base-level changes) but also to other external controls, including total catchment relief, bedrock lithology and human activities (Bull, 1991). Recently, the role of allocyclic mechanisms has received significant attention (e.g., Antoine, 1994; Fuller et al., 1998; Krzyszkowski and Stachura, 1998; Antoine et al., 2000; Houtgast et al., 2002; Macklin et al., 2002; Nott et al., 2002; Jain and Tandon, 2003; Pan et al., 2003; Starkel, 2003; Litchfield and Berryman, 2005; Robustelli et al., 2005; Sun, 2005; Eriksson et al., 2006; Westaway et al., 2006; Gwendolyn and van Balen, 2007). Still, changes in the interplay between climatic and tectonic controls on the fluvial system may be highlighted through in-depth site investigation using geomorphological/stratigraphical techniques. In fact, alluvial terraces may reveal a wealth of palaeoenvironmental

data, allowing detailed interpretation of depositional systems and providing valuable insights into basin geometry changes as the transition from widespread planation to valley development in response to allocyclic mechanisms (Antoine, 1994; Fuller et al., 1998; Macklin et al., 2002; Robustelli et al., 2005). Moreover, chronological dating or sequential reconstruction of genetic/evolutionary processes recorded in the alluvial successions can be achieved through cross-cut relationships and analysis of overlying and interbedded soils. This paper aims to give a contribution to these issues, focusing on (i) description and correlation of alluvial terraces of the northern Ionian coastal belt between the Trionto and Colognati River catchments; (ii) characterisation of the different stages of soil development on the terraces staircase, in order to evaluate the role of time and climate on it and (iii) evaluation of the mechanisms of terrace formation, with particular reference to the relative controls played by tectonics and baselevel changes. 2. Geological setting The Calabrian Arc, consisting of Hercynian crystalline basement and overlying Mesozoic and Cenozoic sedimentary rocks (Amodio Morelli et al., 1976; Critelli, 1999; Bonardi et al., 2005), represents a continental fragment within the arc-shaped Mediterranean fold and thrust belt. The progressive displacement and deformation of the former Calabrian thrust belt has occurred since the middle Miocene as an effect of local extension or, possibly, as a result of middle Miocene thrust loading in response to the development of wrench tectonics (Turco et al., 1990; Knott and Turco, 1991; Schiattarella, 1998; Van Dijk et al., 2000; Tansi et al., 2007 and references therein). The progressive flexuring of the foreland underneath the nappe pile allowed a large wedge-top depozone to be developed (Critelli, 1999; Van Dijk et al., 2000). In the northernmost part of this, the Rossano–S. Nicola fault zone (Van Dijk et al., 2000) played an important role in the development and architectural setting of the Neogene–Quaternary Rossano basin, whose western flank is characterised by wedge-shaped sedimentary bodies,

Fig. 1. Geological sketch map and main middle Miocene–middle Pleistocene left-lateral strike-slip lineaments of northern Calabria. Key: SRFZ: S. Nicola–Rossano Fault Zone; PSFZ: Petilia–S. Sosti Fault Zone; ACFZ: Albi–Cosenza Fault Zone; FCFZ: Falconara–Carpanzano Fault Zone; OCFZ: Ospedale–Colosimi Fault Zone; SDFZ: Sellia–Decollatura Fault Zone; CAFZ: Catanzaro–Amantea Fault Zone (modified after Tansi et al., 2007).

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late Miocene in age, displaying typical growth strata from bottom to top with a general eastward dip (Fig. 1). The basin infill starts with a Serravallian–Tortonian basal transgressive sequence unconformably lying on the Palaeozoic basement, consisting in alluvial and fan-delta conglomerates, passing upward to marls, siltstones with interbedded graded calcarenites, turbiditic sandstones and silty marls (Bonardi et al., 2005). During the Messinian, the Rossano basin records an evaporitic sedimentation (limestones, marly limestones, gypsum, clay-marls, upward passing to gypsumarenites) truncated by the emplacement of large-scale olistostromes made of Variegated Clay (Ogniben, 1973). Sedimentation during the late Messinian consists again of siliciclastic deposits, unconformably sealed by upper Pliocene–lower Pleistocene terrains (Ciclo suprapliocenico–pleistocenico sensu Vezzani, 1968) (Roda, 1964; Vezzani, 1968; Ogniben, 1973; Critelli, 1990). According to Vezzani (1968), the Ciclo suprapliocenico–pleistocenico consists of a transgressive–regressive cycle. In the study area, this cycle starts with the

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deposition of fossiliferous beach sandstones grading upward into gray clay, which pass upward into conglomerates and sandstone. Moving to the east, this is mainly represented by a clay succession whose upper portion, based on fission-track dating of an interbedded ash layer, dates back to middle Pleistocene and should mark the onset of uplift (Bigazzi and Carobene, 2004). The regional uplift that affected northeastern Calabria is witnessed by the marine terrace staircases widespread throughout the Ionian coast (Ciaranfi et al., 1983; Gliozzi, 1987; Cosentino and Gliozzi, 1989; Amato et al., 1997; Cucci and Cinti, 1998; Molin et al., 2002; Carobene, 2003; Zecchin et al., 2004). The interaction between tectonics, climate and sea level changes allowed the formation of a marine and alluvial terrace staircase; the uplift rates inferred since the middle Pleistocene are about 1 mm/y to the west (Molin et al., 2002) and 0.46–0.69 mm/y to the east (Carobene, 2003). In particular, Molin et al. (2002) recognised five orders of alluvial terraces, whereas Carobene (2003) recognised four orders of marine terraces, eastward of the Trionto River. The main soil types developed

Fig. 2. Geological sketch map of the study area between the Colognati and Trionto River catchments. 1) Holocene deposits; 2) alluvial conglomerate (upper Pleistocene); 3) alluvial conglomerate (late middle Pleistocene); 4) deltaic deposit (middle Pleistocene); 5) alluvial conglomerate (early middle Pleistocene); 6) sedimentary clastic wedge consisting of (a) shelf clay grading laterally into (b) alluvial and deltaic conglomerate and sandstone (late lower Pleistocene); 7) pre-Quaternary bedrock; 8) fault.

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on these terraces, as well as along the main alluvial and coastal plains and lower reaches of mountain slopes (Dimase and Iovino, 1996; ARSSA, 2003), are represented by Alfisols, Inceptisols and Entisols according to Soil Taxonomy (Soil Survey Staff, 2006). 3. Methods This work was achieved through multidisciplinary geomorphological, pedological and stratigraphical approaches. The geomorphological analysis, focused on alluvial terraces, was carried out by means of large-scale field survey and mapping supported by air photo interpretation. The terrace surfaces, located along the trunk stream channels of the major catchments, were identified and mapped using large-scale topographical sheets (1:5000 and 1:10,000) and air photographs (1:10,000). In order to identify and describe the relationships between the terraced alluvial sedimentary cover and the underlying successions, a careful geological survey, coupled with the analysis of the fossiliferous content, was performed. Some benchmark soil profiles (representing a soil chronosequence, where spatial differences among soils are mainly related to different time spans of soil development, assuming time as the main forcing factor, e.g., Huggett, 1998) were selected on each order of terrace. They were described in the field in terms of morphological features and sampled for chemical analyses. In order to compare the different

terraced surfaces, the degree of pedogenetic maturity of the soils was estimated by means of three different weathering indices: the redness rating (RR) proposed by Torrent et al. (1980), the chemical index of alteration (CIA) (Nesbitt and Young, 1982) and the index (Fed − Feo)/ Fet (Arduino et al., 1984). In particular, the redness rating was estimated on the basis of the matrix colour in the Munsell notation by applying the formula: RR = ð10 − HÞ⁎C = V

ð1Þ

where C = chroma, V = value and H represents a hue-related numerical value. The CIA was calculated as the ratio: Al2 O3 =ðAl2 O3 þ CaO þ Na2 O þ K2 OÞ

ð2Þ

where CaO represents the Ca content in silicate minerals only. The weight percent of metal oxides was measured by ray fluorescence spectroscopy (XRFS) with a Philips PW 1480 instrument. For each profile, the index was recalculated by taking into account the thickness of each horizon (h) and the total thickness of horizons separated by erosive discontinuities (H), as: X weighted mean CIA = ½h⁎CIA = H ð3Þ The third index was obtained on the basis of different forms of iron occurring in soils, such as total iron (Fet), dithionite-citrate extractable

Fig. 3. (A) Sketch map showing the main morphological features of the study area and location of soil profiles. 1) Soil profiles; 2) fifth-order terrace; 3) fourth-order terrace; 4) third-order terrace; 5) second-order terrace; 6) first-order terrace; 7) gently rolling landscapes. (B) Cross-cut relationships among alluvial terraces occurring along the right side of the Coserie River valley (equidistance of contour-lines is 10 m); the framed area indicates the location of the area shown in Fig. 5.

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(Fed) and ammonium-oxalate (Feo) extractable forms, respectively, estimating the amount of total, free (crystalline + amorphous) and amorphous iron oxides/hydroxides. The index is based on the fact that free iron forms (Fed) and crystalline iron forms (Fed − Feo) tend to increase with the degree of pedogenic evolution. The different iron forms were determined by selective extraction techniques (ammonium-oxalate and dithionite-citrate bicarbonate) (MiPAF, 2000) and were measured by inductively coupled plasma mass spectrometry (ICP-MS). The total amount of Fe was measured by XRFS. This index was weighted similarly to the weighted mean CIA, as follows: X weighted mean index = ½h⁎ðFed − Feo Þ = Fet  = H ð4Þ 4. Geology and geomorphology The study area is located on the Ionian coastal belt of Calabria, from the northern slope of the Sila Massif to the sea, between Rossano and Capo Trionto (Fig. 1). Here, the Sila Massif is topped by a low-relief summit surface at an altitude of ca. 1000 m asl; its northern slope dips down abruptly to the hilly coastal belt that attains a maximum elevation of about 480 m asl. Stream dissection allowed the development of flatirons in gently to moderately dipping homoclinal sequences of Miocene terrains. Stepped surfaces corresponding to well-preserved terraces form west-striking staircase landforms in the northern front of the interfluve ridges and north-striking staircase along valley sides. They unconformably lie upon complex Pliocene and

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Pleistocene deltaic and marine depositional systems (Fig. 2). This succession consists of beach sandstones grading upward into gray silty–clayey deposits, not older than Sicilian ones on the basis of Globorotalia truncatulinoides excelsa and Loxoconca diademata that we found therein. These sediments pass upward to conglomerates and sandstones with interbedded metres-thick silty–clayey layers. Based on lateral and vertical facies changes, the deposits at issue form a 250 m-thick, complex sedimentary clastic wedge (hereinafter called SCW). It consists of superimposed and juxtaposed deltaic and, subordinately, alluvial and beach depositional systems. The sedimentary successions cropping out in the study area grade laterally (to the east) into clay deposits described in detail by Bigazzi and Carobene (2004), onto which a marine terrace staircase developed (Carobene, 2003). On the basis of morphostratigraphic evidence, the deposits of the first-order terrace can be correlated to the oldest alluvial sediments underlying the highest terraced surface of the study area. This represents the basic tool that allowed us to reconstruct the landscape evolution. Terraced aggradational surfaces occurring in the study area are located between 220 and 30 m asl: they consist of remnants of alluvial terraces onto which a few metres to a few tens of metres thick fluvial deposits are sometimes preserved, although partly eroded at the top. The most significant break in slope on the ridges is at about 150 m in elevation, between the first-order terrace and the lower staircase. The identified individual surfaces have been grouped and classified into five elevation orders (Fig. 3). The distribution of these groups in

Fig. 4. Stratigraphic logs of soil profiles. 1) Alluvial gravels and sands; 2) alluvial sands; 3) clay deposits; 4) not sampled layers; 5) eluvial tongues; 6) clay coatings; 7) terrace order.

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Fig. 5. Overview of the studied alluvial terraces staircase (T1–T4) located on the right side of the Coserie River. It is worthy to note the telescopical arrangement of T4 and T3 terraces and the convergence of the same terraces upstream.

the study area shows a narrow band of the studied terraces. They were correlated on the basis of surface morphology, cross-cut relationships, and by comparing the degree of development of associated soil profiles, whose pedostratigraphic logs are reported in Fig. 4. 4.1. The alluvial terraces In the study area, a flight of five stacked alluvial terraces (Fig. 5) lies downstream of gorges cut in the crystalline bedrock. Among these five terraces, the lower ones extend downstream for 2 km and are not preserved elsewhere within the catchments. The terraces are generally paired with alluvial deposits made of subrounded, pebble–cobble gravels, sand and subordinately silt. All terraces rest on a bedrock strath and are widely distributed in the study area, although confined to the lower reaches of the river catchments. 4.1.1. The Bucida terrace The Bucida terrace (T1), ranging between 218 and 154 m in elevation, is up to 1700 m long and 800 m wide; it is the highest terrace, apart from some small relics of alluvial deposits occurring at 471 m asl, an elevation higher than the present watershed between the Coserie and Trionto River catchments. A paired terrace also exists at about 200 m asl in the eastern sector of the study area. The Bucida terrace sedimentary body is quite well exposed. It directly overlies Miocene terrains and lower-middle Pleistocene deltaic deposits. Its basal part is clearly visible in several places along the Bucida treads; the terrace thickness is 30 m southward and decreases to 10 m northward, where the deposits hang above an E–W striking fault scarp (Figs. 2 and 6). The fluvial conglomerates characterising the Bucida terrace are well exposed along side walls of small gorges, but exposures are never higher and longer than a few metres (Fig. 7A). Field observations of the basal contact, carried out at several sites on the right side of the Coserie River, highlight that alluvial deposits unconformably overlie Gilbert-type and shelf-type deltaic deposits and taper on Miocene terrains southward. Sediments consist of plutonic (granite and granodiorite) and medium- to low-grade metamorphic gravels (gneiss, micaschist and phyllite), up to 70 cm in diameter, deriving from the Sila Massif basement, alternating with medium to coarse sand lenses, to form small fining upward successions. Subordinately sedimentary clasts (sandstone, siltstone and limestone) occur,

stripped from the pre-middle-Pleistocene substrata siliciclastic rocks that can be observed especially on the southern and western portions of the study area, whereas marly rocks are found to the east. On the Bucida terrace, soil profiles (P2 to P7) are variably developed and preserved. They show evidence of erosive truncation and lack surface horizons, whereas they exhibit typical deep clayilluviated (argillic, Bt) horizons (sensu Soil Survey Staff, 2006) exposed at the topographic surface or buried by younger alluvial deposits and/ or soils with similar features. Surface and buried soils are separated by lithological discontinuities (sensu Soil Survey Staff, 2006) clearly marked by erosive surfaces. Moreover, occasional whitish eluvial tongues (e.g., soil profile P6bis; Fig. 7B) and common iron–manganese segregations may occur. An older, widespread, always buried and truncated paleosol (profile P1) underlies (and therefore predates) the upper fluvial and deltaic deposits belonging to the upper portion of the Ciclo suprapliocenico–pleistocenico. Soil profiles P1 and P2 include some carbonatic clasts and coherently showed some carbonate reaction to the 10% HCl field test, as also confirmed by the total CaCO3 percentage measured in the laboratory (Table 1). 4.1.2. The Armania terrace The Armania terrace (T2) stands ~50 m below the outer edge of the Bucida terrace, reaching 120 m in elevation. It consists of terrace ridges ranging from 40 to 400 m in width and up to 500 m in length, located on the eastern side of the Coserie River. This terrace is entrenched in the dissected Bucida Terrace above erosional scarps that commonly reach about 40 m in height (Figs. 5 and 6). The fluvial conglomerates, characterising the T2 terrace, rest unconformably on lower-middle Pleistocene deltaic and marine deposits and on Miocene terrains (upstream within the Coserie River catchment). Because of the dearth of exposures that affects terrace treads, the maximum thickness (~ 10 m) of fluvial deposits can be observed only on the west side of the Coserie River. They consist of stratified, pebble and cobble conglomerates, alternating with stratified sandstone beds or lenses. They are dominated by plutonic and metamorphic gravels fed by the Sila Massif, and by occasional gypsum-arenite along the eastern sides of the terrace, indicating erosion of the Miocene succession. Sandstone beds, occurring in the upper part of the succession, are sometimes overprinted by pedogenetic features. Paleosols are developed both at the terrace surface (e.g., soil profile P13) and alternated

Fig. 6. Overview from the north showing the morphologic relationships among alluvial terraces. In the foreground, a W–E trending fault scarp, hanging Bucida conglomerates and separation from T1 and T2 terraces are very noticeable; in the background, gently rolling landscapes (square 7 of legend in Fig. 3).

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Fig. 7. (A) T1 terrace: clast-supported, sheet-like conglomerates of pebble- to cobble-grade resting erosively on deltaic sandstone (see text for details). (B) Soil profiles P6 (surface) and P6bis (buried) alternated with alluvial conglomerates of T1 terrace. (C) T2 terrace: pebble and, subordinately, cobble conglomerates alternating with stratified sandstone overprinted by pedogenetic features. Paleosols are both at the terrace surface (P11) and buried (P11bis). (D) T3 terrace: soil profile P12 characterised by truncated subsoil horizons.

with gravels and sands in the upper portion of the alluvial succession (e.g., soil profiles P11, P11bis and P13) (Fig. 7C). They show illuvial clay coatings and are often truncated at the top. In some locations, subvertical eluvial tongues occur within the rubified matrix (profile P11bis).

The soil profiles developed on the three different orders of terraced surfaces (profile P12 on T3 terrace, P10 on T4 and P8 on T5) are reddish in colour and rich in illuvial clay coatings, although the T3 terrace soil appears very thin as a consequence of particularly intense surface erosion (Fig. 7D).

4.1.3. The Malvitano terrace staircase (T3–T5) The three lowest/youngest terraces (T3, T4, T5) are widespread throughout the study area and stand between 87 and 30 m asl. The third-order terraces (T3) are about 80 m asl, with top surfaces up to 900 m large and 250 m wide. The fourth-order terraces (T4) are about 60 m asl, with top surfaces up to 1000 m length and 300 m wide, whereas the lowest ones (T5) are about 45 m asl, with top surfaces up to 600 m length and 400 m wide. They are generally paired and are made of b10 m-thick alluvial deposits, resting on a bedrock strath of lower-middle Pleistocene deposits. Furthermore, the three alluvial terraces are (noticeably) telescopically inset within each other, producing a complete suite of downward-diverging terrace surfaces as shown in Fig. 5. Field observations of the basal contact suggest the hypothesis that alluvial conglomerates filled paleovalleys, laterally extending over tens of metres. The T3 terrace is the highest/oldest alluvial unit. In the Colognati and Coserie lower catchments, treads exhibit a very smooth surface standing about 5 m above the T4 terrace, which can be easily identified on both valley sides of the Coserie River between the T3 and T5 terraces. All three terraces are made of a few metres thick alluvial deposits, mainly composed of moderately sorted conglomerate beds, characterised by a clast-supported texture and by a SSE-dipping imbrication; beds have a sheet-like geometry with rare concave-up bases. Sandstone beds and lenses locally occur. Granitoids and medium- to low-grade metamorphic rocks in the coarse fraction of the alluvial deposits are coupled, mainly on T4 terrace, with sandstone and siltstone.

4.2. Alluvial depositional environment The terraced fluvial deposits cropping out in the study area consist of fining upward successions lying unconformably on Miocene, Pliocene and lower to early-middle Pleistocene deposits; their paleodepositional environment has been detected through the analysis of their main textural and sedimentological features. Concerning the T1 terrace basal unconformity, its shape, changes in deposit thickness and the northwesterly-directed paleocurrents support the hypothesis that fluvial conglomerates represent the fill of a paleovalley. Where complete, the basal portion of each succession consists of clast-supported, sheet-like conglomerates of pebble- to cobble-grade; occasionally, cobble- to boulder-grade units occur. Beds show nonerosive bases and extend laterally for metres. These characteristics suggest vertical accretion and migration of low-relief bars in a shallow gravel-bed braided stream (Miall, 1977; Rust, 1978; Miall, 1996; Collinson, 1986). They pass upward into clast-supported, trough crossstratified conglomerates characterised by symmetrical concave-up bases; averaged sizes of thickness and width of individual units range from 0.5–0.8 and 5–6 m, respectively. They are interpreted as a multistorey channel fill, characterised by fast migration and fill of small and concave-up channels (Ramos and Sopeña, 1983; Komatsubara, 2004). These deposits grade upward into and alternate with pebble-grade, clast-supported conglomerates; in turn, they alternate with laminated sandstone beds and lenses showing rare rootlets and possible

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Table 1 Some selected soil features of the studied profiles. Profiles

Horizons

Depth (cm)

Color (dry)

Structure

Texture

Skeletal fraction

Fe–Mn features

Clay coatings

CaCO3 (%)

P1 P1 P1 P1 P2 P2 P2 P2 P3 P3 P4 P4 P4 P4 P5 P5 P5 P6 P6 P6 P6bis P6bis P7 P7 P11 P11 P11 P11bis P11bis P13 P13 P12 P12 P10 P10 P10 P10 P8 P8 P8

Bt 2Btb1 2Btb2 2Btb3 Bt1 Bt2 2Btb1 2Btb2 Bt1 Bt2 Ap Bt1 Bt2 Bt3 Bt1 Bt2 2Btb Bt BEtg EBtg BEtgb EBtgb Bt1 Bt2 Ap Bt1 Bt2 BEtgb EBtgb Bt1 Bt2 Bt1 Bt2 Ap Bt1 Bt2 Bt3 Bt1 Bt2 Bt3

0–70 70–105 105–140 140–200 + 0–80 80–140 140–240 240–300+ 0–28 28–70 0.5–20/30 20/30–35 35–60/80 60/80–100 0.5–15 15–35/40 35/40–100 0–60/70 60/70–20/130 120/130–170 0–60/70 60/70–130+ 0–15 15 – 25 + 0.5–15/20 15/20–40 40–100 0–20 20–30+ 0.5–75 75–120 0.5–30 30–95 0.5–10/15 10/15–40/45 40/45–85 85 –135 0–15/20 15/20–75 75–170/180+

7.5 YR 4/6 10 YR 5/6 10 YR 4/4 7.5 YR 4/6 10 YR 3/6 7.5 YR 3/4 7.5 YR 2.5/3 5 YR 4/6 5 YR 4/6 5 YR 4/6 10 YR 4/6 5 YR 4/4 5 YR 4/6 7.5 YR 5/6 7.5 YR 4/6 7.5 YR 3/4 5 YR 4/6 10 YR 4/6 7.5 YR 4/6 10 YR 4/6 7.5 YR 4/6 7.5 YR 5/8 7.5 YR 4/6 7.5 YR 5/8 10 YR 5/4 10 YR 4/6 7.5 YR 4/6 10 YR 4/6 10 YR 5/8 10 YR 4/6 10 YR 5/6 7.5 YR 4/6 10 YR 4/4 7.5 YR 4/4 7.5 YR 4/6 7.5 YR 3/4 7.5 YR 4/6 7.5 YR 4/4 10 YR 4/6 7.5 YR 4/6

vc AB vc AB m–c AB(P) c AB (P) c AB c AB c AB c AB f–c AB f AB f–c SB m–c AB m–c AB vc AB f–c AB–SB f–c AB c AB–SB f–c AB f–vc AB f–c AB c AB m–c AB (P) f–c AB f–m AB f–c AB–SB m–c AB f–c AB f–c AB m AB (P) m–c AB–SB m AB f–m SB m–c SB c AB m–c AB f–c PB c AB c AB m–c AB (P) f–c AB

L L L CL L L SnCL CL CL SnL L L CL SnCL L L SnCL L L L SnL L C CL L L L SnCL SnL SnCL SnCL SnCL SnCL SnL SnL SnL SnL SnL SnL SnL

+ + (+) ++ + + + ++ +++ ++++ ++ ++ ++++ + + + +++ + (+) (+) ++ (+) + ++ + + + ++ ++ ++ (+) ++ ++ ++ +++ +++ +++ ++ +++ +++

0 0 ++ + (+) + + + + + 0 + + (+) (+) 0 0 ++ ++ + 0 ++ 0 0 0 0 ++ 0 ++ 0 0 (+) (+) 0 0 0 0 0 + +

++ + ++++ ++ ++ +++ +++ ++ ++++ ++ 0 +++ ++++ ++ ++ +++ ++ +++ ++++ ++ ++ ++++ +++ ++ + ++ ++ +++ ++ +++ ++ ++ +++ ++ ++++ ++++ ++ +++ +++++ ++++

3.9 2.9 – 1.9 – – – 1.9 – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

Structure: AB: angular blocky; SB: subangular blocky; P: prismatic; c: coarse; vc: very coarse; m: medium; f: fine. Texture: C: clay; L: loam; CL: clay loam; SnCL: sandy clay loam; SnL: sandy loam. Relative abundance of other features: 0: null; (+): very rare; +: rare; ++: common; +++: frequent; ++++: abundant; +++++: very abundant.

pedogenetic traces, thought to represent floodplain of a braided river stream whose main channels shifted laterally (Vincent, 2001). As regards T2 terrace treads, because of the lack of extensive outcrops, sedimentological analysis has concerned few sites along stream incisions and road cuts. Deposits consist of stratified conglomerates and sandstones, the latter sometimes organized in lenses. The conglomerate beds are characterised by a clast-supported texture and by a southward-dipping imbrication of clasts. Beds are ungraded or normally graded with an overall tabular geometry. Locally concave-up, erosive bases have also been observed. Intervening sandstone beds and lenses, up to 0.35 m thick, are composed of moderately sorted, medium to coarse-grained sandstones; sedimentary structures are absent, but flat-lamination locally occurs. The dominance of crudely stratified, tabular conglomerates indicates that deposition was laterally extensive, even though the occurrence of lenses is also noticeable. As a whole, this facies association is interpreted as formed by growth and migration of braid bars in high energy gravel bed rivers (Miall,1977; Rust,1978; Miall, 1996; Collinson, 1986). The channel-like bedforms are representative of channels cutting across bar top and/or front during falling flood stages; in addition, stratified sandstones represent deposition from heavily sediment-laden flows during waning floods (Todd, 1989; Maizels, 1993; Jo and Chough, 2001). Terraced deposits of the Malvitano staircase (T3, T4 and T5) consist of horizontally stratified conglomerates suggesting high energy, traction-current processes and interpreted as being formed by the

migration of shallow and broad braided channels with low-relief bars in a gravel braided stream. The lack of planar cross-beds (Gp lithofacies), whose origin requires a deep-water channel (Bluck, 1979; Steel and Thompson, 1983), provides evidence of shallow channel depth. Conglomerates locally alternate with sandstone beds and lenses consisting of horizontally stratified, moderately sorted, fine to coarse-grained sandstones. Because of the lack of thick and extensive outcrops of the terraced fluvial deposits in the study area, we were unable to clearly identify the architectural elements useful to assess a specific fluvial style. However, the analysis of the main sedimentary features allowed us to interpret their depositional environment as shallow gravel-bed braided river. In addition, field observations suggest that the inferred braided pattern might be reasonably considered similar to the present pattern of rivers dissecting the study area. 4.3. Pedogenic indices All soil profiles of the chronosequence on the terrace staircase at issue represent Alfisols (sensu Soil Survey Staff, 2006), on the whole characterised by similar main features (clay coatings, reddish colours, Fe–Mn features, occasional eluvial tongues). Their degree of development was compared using three different weathering indices, which allowed us to propose some pedogenic correlations among the different terraced surfaces.

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Fig. 8. Diagrams showing (A) the redness rating of all soil horizons, (B) the weighted mean CIA and (C) the weighted mean index of weathering ∑ [h ⁎ (Fed − Feo) / Fet] / H. See the text for details.

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In particular, the redness rating (Fig. 8A) assumes that rubification (i.e., the reddening of soil matrix from iron-oxide segregation) becomes more intense as far as soil development increases. Higher values are measured for most profiles belonging to the Bucida terrace, as expected, whereas all the others have significantly lower values independently from different terrace and soil ages. Moreover, the RR was null in numerous horizons of various soil profiles. All soil profiles show very high values of the weighted CIA index, ranging between 0.8 and 0.95 (Fig. 8B). On the whole, the paleosols located on the T1 terrace exhibit the highest values (except soil profile P2), whereas those located on the youngest surfaces show unexpectedly partly comparable values. Notably, this index reflects the progressive removal of labile cations (Ca2+, Na+, K+) relative to stable constituents (Al3+, Ti4+) during weathering as a response to the alteration of feldspars into clay minerals. Although in the original formula the CaO percentage is related to silicate minerals only, the consideration of its total amount seems not to considerably affect a correct evaluation of weathering intensity, despite the presence of carbonate-bearing components. In fact, CaCO3 is completely absent in almost all soil horizons, except in very few samples of profiles P1 and P2, where it never exceeds 3.9% and might therefore very poorly underestimate CIA values. The use of the weighted index was suggested by the occurrence, in some profiles, of lithological discontinuities (sensu Soil Survey Staff, 2006) separating different sedimentary cycles followed by phases of pedogenetic development. The third index, (Fed − Feo)/Fet, is very reliable to compare and correlate exposed or buried surfaces related to different geomorphological units (namely river terraces of different age in the study area) and therefore contributes to the reconstruction of the Quaternary landscape evolution. It is among the best-suited tool for the study of soil chronosequences, as supported by recent scientific literature (e.g., Wagner, 2005; Scarciglia et al., 2006; Tsai et al., 2007). It is based on the fact that free iron forms (Fed) and crystalline iron forms (Fed − Feo) tend to increase with the degree of pedogenic evolution, indicating an overall relation with soil (and terrace) ages. Because of the occurrence of erosive discontinuities within some soil profiles, this index was weighted on the basis of horizons thicknesses (Fig. 8C). Most soil profiles of the Bucida terrace (T1) have the highest values, as expected. In contrast, the paleosols developed on the younger terraces (T2 to T5) show lower but more variable values, on the whole. In some profiles, a discontinuous trend is noticeable and can be related to the morphological discontinuities already described in the field. 5. Discussion Many studies have focused on the relative roles of tectonics, climatic oscillations and sea-level change on the switch between aggradation/degradation behaviour of rivers. Our study suggests that tectonic activity and sea level were key factors that mainly affected the formation of the five alluvial terraces in the investigated area. The main features described in the paleosols interbedded within and overlying the fluvial successions, such as the abundance of clay coatings and widespread rubification of the matrix, account well for a warm and humid, seasonally-contrasting soil-forming environment, namely xeric (pedo)climatic regime. These temperature and moisture conditions suggest that major phases of soil development occurred during interglacial periods (e.g., Catt, 1989; Fedoroff, 1997; Scarciglia et al., 2006), not excluding that some pedogenetic processes also developed during intervening glacials. As a first approximation, it would indicate that alluvial aggradation mainly occurred during glacials. Nonetheless, climatic control on stream incision would have occurred when low sediment availability was concurrent with high water discharge (Schumm, 1965). Such conditions would have occurred, for example, at the beginning of an interglacial period. However, this is in contrast with the above quoted dominantlyinterglacial soil formation, as well as with the main sedimentological

features of the braided alluvial systems observed in the successions (e.g., size of transported clasts and their sedimentary facies associations). They clearly indicate high water discharge but not low sediment availability, therefore suggesting that stream degradation (terracing) might have developed mainly during glacial (as also supported by the truncation of interglacial soils), probably as a consequence of sea level fall (see below). In addition, the high comparability between the past gravel-bed braided pattern inferred and the present-day river pattern (i.e. related to an interglacial analogue as the Holocene is considered) further supports that prominent aggradation phases could have occurred also during interglacials. Similarly, despite the lack of precise paleohydrological reconstructions (not achievable for the limited extension and incomplete exposure of the terraced fluvial deposits), water discharge during past interglacials can be approximately estimated comparable to the present-day one. In fact, the chronosequence studied suggests a dominant xeric soil moisture regime, which also nowadays characterises the terraced and coastal reaches of study area (mean annual precipitation ranging from about 590 to 980 mm according to elevation (Dimase and Iovino, 1996); udic conditions (sensu Soil Survey Staff, 2006) occur at present on the inland mountainous belt of the river catchments (ARSSA, 2003), where rainfall may approach 1380 mm/y (Dimase and Iovino, 1996). Furthermore, although a general trend showing a progressive increase in moisture is well-documented in mid-latitude areas at the transition from glacial to the subsequent interglacial phase (e.g., Watts et al., 1996; Allen et al., 1999; Amore et al., 2000), the occurrence of Abies and deciduous Quercus in pollen records from south Italy (Rossignol-Strick et al., 1992; Buccheri et al., 2002; Russo Ermolli and di Pasquale, 2002) clearly points out a persistent availability of moisture in mountainous areas close to the sea, even during glacial periods. In particular, in northern Calabria the dominance of debrisflow deposits related to gravity processes active during glacials (Sorriso-Valvo, 1988, 1990, 1993) and also affecting the present-day slope degradation (Sorriso-Valvo and Sylvester, 1993), coupled with the strong and continuous fluvial sedimentation since OIS 3 inferred from boreholes data (Pagliarulo, 2006), further support the hypothesis that processes of detritus removal and alluvial reworking occurred both during glacials and interglacials. On these bases, climate does not appear to have been the main factor controlling sediment/discharge ratios, as well as aggradation and degradation processes of the alluvial plain. Climate seems rather to have mostly affected modes of detrital production (mainly by physical degradation of the bedrock during glacials and chemical weathering during interglacials), size of detritus and consequent delivery to the river system. As a consequence, we argue that in the study area cyclical switches in fluvial dynamics might be chiefly related to other factors, such as tectonic and sea level changes, as discussed below. The studied alluvial terrace staircase is located to the east and partly overlaps the area where Molin et al. (2002) recognised five orders of alluvial terraces (Fig. 9), which range in elevation between 230 and 125 m asl (first order, OIS 7a), 180–60 m asl (second order, OIS 5e),110– 35 m asl (third order, OIS 5c), 70–25 m asl (fourth order, OIS 5a), 15– 8 m asl (fifth order, OIS 1). Further, on the right side of the Trionto River valley (Fig. 9), Carobene (2003) documented four orders of marine terraces that rest erosively on clayey deposits. The first-order terrace ranges in elevation between 210 and 130 m asl and is referred to OIS 119; the second order ranges in elevation between 120–80 m asl and is related to OIS 7; the third and fourth orders of terrace, hanging between 75–55 m and at about 30 m asl, are referred to substages 5e and 5c/5a, respectively. In order to establish the chronological succession of alluvial terraces, we also examined their lateral relationships with the PlioPleistocene bedrock and the Pleistocene marine terraces cropping out in the nearby areas; on this basis, the following sequence of events may be proposed (Fig. 10).

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Firstly, the crystalline bedrock might have been largely exhumed (Molin et al., 2004) during the Miocene, when it supplied marls, siltstones, sandstones and evaporitic rocks from the Miocene terrains (Barone et al., 2008), resulting in the progressive ENE-ward migration of depocenters. The late Pliocene–early Pleistocene transition marks a strong change in the geological scenario, leading to the submergence of the study area, as well as to the formation of a complex sedimentary wedge, onlapping onto Miocene terrains (Fig. 10A). In agreement with Carobene (2003) and Bigazzi and Carobene (2004), a very slow-rate, long-lasting tectonic subsidence produced, during the lower Pleistocene, a progressive transgression of the sea and hence the deposition of a thick marine clayey sedimentary succession. Subsequently, probably in the middle Pleistocene, the study area recorded the deposition of the SCW. This indicates a strong control by sediment input from continental feeding sources, represented by steep catchments debouching from the mountain front and resulting into seaward migration of middle Pleistocene depositional depocenters. The SCW records the end of the Ciclo suprapliocenico– pleistocenico (Vezzani, 1968), which also crops to the west of the study area (Molin et al., 2002). On the contrary, clay sedimentation continued eastward until OIS 11, which marks the onset of the regional uplift (Bigazzi and Carobene, 2004). By taking into account the occurrence of continental feeding sources to the NE, the SCW may be the result of a depositional regression affecting the area, still characterised by tectonic subsidence, as suggested by the superimposition and juxtaposition of different deltaic depositional systems. This hypothesis is suitable for a long-lasting subsidence period, still affecting the whole area during the middle Pleistocene (Bigazzi and Carobene, 2004). Secondly, marine regression continued during the middle Pleistocene, leading to the development of an erosion surface onto which the Bucida conglomerates were deposited (T1 terrace), as shown in Fig. 10B. This period of relief smoothing might indicate, in agreement with Bigazzi and Carobene (2004), the end of tectonic subsidence but not the onset of uplift, as suggested by the alluvial sequence of the T1 terrace. In fact, it consists of alternating conglomerates and relatively

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mature paleosols, suggesting a fairly long tectonic standstill during which fluvial channels may have switched on an alluvial plain, leading to pedogenesis of the abandoned portions and subsequent aggradation by younger deposits. Finally, the occurrence of a wide shallow paleovalley, as detected from the shape of basal unconformity, coupled with low-relief landscapes correlated to the T1 terrace, provides insights for a widespread planation of landscapes that supports further the hypothesis of the above-quoted tectonic standstill. The geological– geomorphological record of the study area (Pliocene–Pleistocene age of the substratum, alluvial terraces elevation and sedimentary features and the soil characteristics) definitely confirm the data provided by Carobene (2003) regarding marine terraces. On the basis of the above-quoted morphostratigraphic data, T1 terraces are presumably correlated to the first order of marine terraces identified by Carobene (2003). The great extension of the Bucida terrace, the thickness (up to 30 m) and facies associations of alluvial deposits and the features of the interbedded paleosols suggest that T1 terrace depositional sequences recorded more than one interglacial period. For these reasons, we suggest that its formation could be referred to OIS 11-9. This period ends with the onset of regional uplift; following this tectonic standstill period, the study area would have experienced a block faulting event, leading to deep-reaching fluvial incision (T1 dissection) and being responsible for the Bucida terrace displacement. In particular, to the north, the Bucida terrace is bordered by a WEtrending fault scarp, which interrupts its profile and truncates fluvial conglomerates at about 170 m asl. It caused sediment bypassing recorded by late middle-Pleistocene deltaic (Fig. 10C) and alluvial (Fig. 10D) successions, that seal the faults that had displaced the earlymiddle Pleistocene formations. As far as the lowest/youngest terraces are concerned and on the basis of cross-cut relationships among T2 to T5 terraces elevations, correlations with adjacent marine terraces (Carobene, 2003) and interpretation of soil features, tectonically and eustatically induced base-level changes are seen as the main controls influencing stream aggradation/degradation during middle–late Pleistocene (Fig. 10E).

Fig. 9. Possible chronology of the studied terraces by comparing them with alluvial (Molin et al., 2002) and marine (Carobene, 2003) terraces mapped in the nearby areas and correlating to sea level curve (Waelbroeck et al., 2002).

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We must also consider that, due to local uplift rates estimated by Carobene (2003), the occurrence time of sea level peaking was reached before that of the absolute sea level highstand. Subsequently, following the sea level absolute, — during which climate was suitable to develop reddish and clay-illuviated soil profiles, the lowering of sea level started promoting stream erosion and alluvial plain terracing. From these considerations, we may refer the T2 terrace to the OIS 7 and the T3, T4 and T5 terraces to the OIS 5 (substages 5e, 5c and 5a, respectively; Fig. 9). The estimated weathering indices allowed us to deepen in the understanding of the pedogenetic/geomorphic environment and to assess and compare soil development within the chronosequence on the fluvial terrace staircase. The irregular distribution of the redness rating calculated for the paleosols and its null value in various horizons (see above) suggests some local effects of differential textural and other physical properties or microclimatic conditions controlling permeability and drainage, in turn influencing the formation of different Fe-(oxi)hydroxides. In fact, more yellowish colours (10 YR of the Munsell notation, determining null RR values) indicate the dominance of iron hydroxides over oxides, promoted by higher soil water activity and vice versa (Torrent et al., 1983; Diaz and Torrent, 1989). This is also consistent with the occasional presence of whitish eluvial tongues (in transitional EB or BE horizons), representing iron-depleted zones, or other gley (g) features, highlighting at least seasonally hydromorphic (and therefore reducing) conditions. In addition, the irregular RR pattern presumably records the effects of morphodynamic processes evidenced in a variety of field soil features, such as the lack of typical surface horizons and the exposure of the subsoil at surface, the presence of lithological and erosive discontinuities, separating two or more sedimentary cycles and subsequent major phases of pedogenetic development, and burial by younger deposits. The high values of the weighted chemical index of alteration, always comprised between 0.8 and 0.95, indicate an overall high degree of weathering (e.g., Fedo et al., 1995, 1996) of all soil profiles. However, in this case, CIA does not appear very reliable in terms of relative chronology, as it exhibits very slight differences, which are only partly consistent with the different ages of paleosols, whereas in many cases no definite trends occur. This general homogeneity of values suggests (i) a sort of “buffering” effect caused by the truncation of soil profiles (surface erosion), therefore “retrograding” their degree of development towards stages closer to parent materials, which appears more effective for the oldest terraces, coupled with (ii) a more prominent imprint of the latest climatic cycles on the rejuvenated soils, finally minimizing mutual differences. Moreover, the chemical index of alteration reacts highly susceptibly to the inhomogeneous nature of parent rocks, as based on total composition (Wagner, 2005), and does not discriminate between different forms of total elements contributed by primary and neoformed mineral phases; therefore it is revealed to be less sensitive to depict the real degree of soil development in the present chronosequence. Also, the weighted mean values of the iron-based weathering index exhibit a partly irregular pattern, which seems to a certain extent irrespective of the estimated soil and terrace chronology. Nevertheless, it describes better than the other indices the main relationships between pedogenic development of soil profiles and the different terraces, and permitted their overall comparison, as it is almost independent from existing changes in the lithological composition (Wagner, 2005). Almost all soil profiles of T1 terrace show values of the Arduino's index higher than those determined for the younger terraces. The apparent discrepancies among T5 to T2 terrace soils can be interpreted as a response to geomorphic dynamics.

Fig. 10. Plio-Pleistocene evolution sketch of the study area (see the text for details).

G. Robustelli et al. / Geomorphology 106 (2009) 165–179

In particular, field evidence highlight that (i) severe erosion affects some profiles (e.g., P11bis and P12), rejuvenating the degree of pedogenic evolution, whereas (ii) soil aging from soil reworking and redeposition from older profiles (coherently with their topographic position and the intrinsic context of alluvial terraces and stream environments) occurs on others (e.g., P1 and P8). In addition, the anomalously lower values of the oldest soil profile (P1) indicate that its pedogenetic maturity is poor, as also supported by the carbonatebearing (unleached) matrix, because of its early burial and consequent “sealing” from further significant soil-forming processes. As for soil profiles P6, P6bis and P11bis, their relatively lower values might be related also to the occurrence of eluvial/hydromorphic features, enhancing iron-oxide depletion from intense leaching processes. In addition, the discontinuous presence of some carbonate primary components only in soil profiles P1 and P2 suggests some changes (in space and time) in the feeding areas of the river catchments during fluvial aggradation. Despite the above “disturbance” by geomorphic dynamics, the overall moderately high degree of pedogenetic evolution indicated by the main field features and by the pedogenic iron index of the soil chronosequence may give some useful information about timescales of events that led to the formation of the studied flight of river terraces. In fact, although precise and reliable correlation between soils and terrace age were not assessed, the comparison of our data with those obtained in other paleosols of Pleistocene age from different coastal areas of south Italy (Scarciglia et al., 2003, 2006; Wagner et al., 2007), as well as from other Mediterranean sites (e.g., Diaz and Torrent, 1989; Bech et al., 1997; Ortiz et al., 2002; Costantini et al., 2006), suggests time spans of soil formation after final exposure of terrace surfaces of n ⁎ 105 y. This data is consistent with the middle to late Pleistocene terrace chronology that we propose. In addition, pedogenesis intervening between major phases of sedimentary aggradation (testified by erosive discontinuities and buried paleosols) can be estimated in the order of one to some thousands years. 6. Concluding remarks The study area is an active tectonic region with a well-preserved flight of Pleistocene alluvial and marine terraces along the coastal belt. Our studies on the sedimentology, stratigraphy, relative ages, and terrace development allow us to summarize the following general points. Five orders of alluvial terraces are distributed within the lower reaches of the main river catchments, mainly composed of gravel-bed braided stream conglomerates underlying, and locally alternating with, reddish and clay-illuviated soil profiles. Despite the redness rating (RR) and the chemical index of alteration (CIA) did not appear highly reliable to compare soil and terrace ages, their relative chronology has been more reliably detected through the weighted mean values of the (Fed − Feo)/Fet index, as well as by means of geomorphological correlations with marine terraces and referred to middle to late Pleistocene isotopic stages. Stratigraphical and pedological data suggest that stream incision and terracing is not caused primarily by climatic changes but mainly controlled by tectonics and sea level changes (the latter, of course, being in turn directly influenced also by climate), which worked together in causing switches in fluvial dynamics between aggradational and erosional phases. During the middle Pleistocene, the study area experienced a fairly long tectonic standstill, leading to a period of landscape modelling during which Bucida conglomerates (T1 terrace) deposited. The onset of uplift (late middle Pleistocene) caused switches in fluvial dynamics, i.e., river aggraded during relative sea level rise and degraded during relative sea level fall; this resulted in the formation of a well-developed staircase of alluvial terraces. Aggradational phases, producing vertical accretion, occurred during periods of climate amelioration before relative marine highstands; we argue that the

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main role of sea level rise was that of creating accommodation space. Stream erosion and terracing occurred soon after the time of relative high sea levels. The evidence presented above seems to indicate that the studied terraces owe their origin to a cyclic pattern of erosion and deposition. During the final phases of aggradation, deposition was partly accompanied and followed by a prolonged (millennial-scale?) period suitable for pedogenesis taking place. Long-lasting (presumably polycyclical), pedogenetic processes definitely affected the different orders of terraced surfaces after their progressively younger final exposure, with major soil development during the interglacials alternating throughout the Quaternary. Although this study has contributed to the understanding of the late Quaternary evolution of the study area, some caution should be expressed about the applicability of these results at a regional scale, considering the possible high spatial variability of geomorphological setting in a strongly mobile area like northern Calabria. Acknowledgements We are grateful to Marcello Schiattarella (University of Basilicata, Italy), Frank J. Pazzaglia (Lehigh University, PA, USA) and an anonymous reviewer for their critical comments and suggestions, which greatly improved the quality of our manuscript. We also thank William Spataro (University of Calabria, Italy) for his revision of the English language. References Agenzia Regionale per lo Sviluppo e per i Servizi in Agricoltura (ARSSA), 2003. I suoli della Calabria. Carta dei suoli in scala 1:250000 della Regione Calabria. Monografia divulgativa. Programma Interregionale Agricoltura-Qualità — Misura 5, ARSSA, Servizio Agropedologia, Rubbettino Ed., Soveria Mannelli, Catanzaro, Italy, 387 pp. Allen, J.R.M., Brandt, U., Brauer, A., Hubberten, H.W., Huntley, B., Keller, J., Kraml, M., Mackensen, A., Mingram, J., Negendank, J.F.W., Nowaczyk, N.R., Oberhansli, H., Watts, W.A., Wulf, S., Zolitschka, B., 1999. Rapid environmental changes in southern Europe during the last glacial period. Nature 400, 740–743. Amato, A., Belluomini, G., Cinque, A., Manolio, M., Ravera, F., 1997. Terrazzi marini e sollevamenti tettonici quaternari lungo il margine ionico dell'Appennino lucano. Il Quaternario (Italian Journal of Quaternary Science) 10 (2), 329–336. Amodio Morelli, L., Bonardi, G., Colonna, V., Dietrich, D., Giunta, G., Ippolito, F., Liguori, V., Lorenzoni, S., Paglionico, A., Perrone, V., Piccarreta, G., Russo, M., Scandone, P., Zanettin Lorenzoni, E., Zappetta, A., 1976. L'Arco Calabro-Peloritano nell'orogene Appenninico-Maghrebide. Memorie della Società Geologica Italiana 17, 1–60. Amore, F.O., Ciampo, G., Di Donato, V., Esposito, P., Russo Ermolli, E., Staiti, D., 2000. An integrated micropalaeontological approach applied to Late Pleistocene–Holocene palaeoclimatic and palaeoenvironmental changes (Gaeta Bay, Tyrrhenian Sea). In: Hart, M.B. (Ed.), Climates: Past and Present. Geological Society, London, Special Publication, vol. 181, pp. 95–111. Antoine, P., 1994. The Somme valley terrace system (northern France): a model of river response to Quaternary climatic variations since 800,000 B.P. Terra Nova 6, 453–464. Antoine, P., Lautridou, J.P., Laurent, M., 2000. Long-term fluvial archives in NW France: response of the Seine and Somme rivers to tectonic movements, climatic variations and sea-level changes. Geomorphology 33, 183–207. Arduino, E., Barberis, E., Carraro, F., Forno, M.G., 1984. Estimating relative ages from ironoxide/total-iron ratios of soils in the western Po Valley (Italy). Geoderma 33, 39–52. Barone, M., Critelli, S., Dominici, R., Muto, F., 2008. Detrital modes in a late Miocene wedge-top basin, northeastern Calabria, Italy: compositional record of wedge-top partitioning. Journal of Sedimentary Research 78, 693–711. Bech, J., Rustullet, J., Garrigó, J., Tobías, F.J., Martínez, R., 1997. The iron content of some red Mediterranean soils from northeast Spain and its pedogenic significance. Catena 28, 211–229. Bigazzi, G., Carobene, L., 2004. Datazione di un livello cineritico del Pleistocene medio: relazioni con sedimentazione, sollevamento e terrazzo marini nell'area CrosiaCalopezzati in Calabria (Italia). Il Quaternario — Italian Journal of Quaternary Sciences 17 (2/1), 151–163. Bluck, B.J., 1979. Structure of coarse grained braided stream alluvium. Transactions of the Royal Society of Edinburgh. Earth Sciences 70, 181–221. Bonardi, G., De Capoa, P., Di Staso, A., Perrone, V., Sonnino, M., Tramontana, M., 2005. The age of the Paludi Formation: a major constraint to the beginning of the Apulia verging or ogenic transport in the northern sector of the Calabria Peloritani Arc. Terra Nova 17 (4), 331–337. Buccheri, G., Capretto, G., Di Donato, V., Esposito, P., Ferruzza, G., Pescatore, T., Russo Ermolli, E., Senatore, M.R., Sprovieri, M., Bertoldom, M., Carella, D., Madonna, G., 2002. A high resolution record of the last deglaciation in the southern Tyrrhenian Sea: environmental and climatic evolution. Marine Geology 186 (3–4), 447–470. Bull, W.B., 1990. Stream-terrace genesis: implications for soil development. In: Knuepfer, P.L.K., McFadden, L.D. (Eds.), 1990. Soils and Landscape Evolution. Binghamton Geomorphology Symposium, Geomorphology, vol. 3, pp. 351–368. Bull, W.B., 1991. Geomorphic Responses to Climatic Change. Oxford University Press, New York. 326 pp.

178

G. Robustelli et al. / Geomorphology 106 (2009) 165–179

Carobene, L., 2003. Genesi, età, sollevamento ed erosione dei terrazzi marini di CrosiaCalopezzati (Costa ionica della Calabria-Italia). Il Quaternario (Italian Journal of Quaternary Science) 16 (1), 43–90. Catt, J.A., 1989. Relict properties in soils of the central and north-west European temperate region. Catena Supplement 16, 41–58. Ciaranfi, N., Guida, M., Iaccarino, G., Pescatore, P., Pieri, P., Rapisardi, L., Ricchetti, G., Sgrosso, G., Torre, M., Tortorici, L., Turco, E., Di Scarpa, R., Cuscito, M., Guerra, I., Iannaccone, G., Panza, G.F., Scandone, P., 1983. Elementi sismottettonici dell'Appennino meridionale. Bollettino della Società Geologica Italiana 102, 201–222. Collinson, J.D., 1986. Alluvial sediments. In: Reading, H.G. (Ed.), Sedimentary Environment and Facies. Blackwell Scientific Publications, Oxford, UK, pp. 20–62. Cosentino, D., Gliozzi, E., 1989. Considerazioni sulle velocità di sollevamento di depositi Eutirreniani dell' Italia Meridionale e della Sicilia. Memorie della Società Geologica. Italiana 41, 653–665. Cosentino, D., Gliozzi, E., Salvini, F., 1989. Brittle deformations in the Upper Pleistocene deposits of the Crotone Peninsula, Calabria, southern Italy. Tectonophysics 163, 205–217. Costantini, E.A.C., Lessovaia, S., Vodyanitskii, Yu., 2006. Using the analysis of iron and iron oxides in paleosols (TEM, geochemistry and iron forms) for the assessment of present and past pedogenesis. Quaternary International 156–157, 200–211. Critelli, S., 1990. Geological setting of the Trionto River basin. Excursion Guidebook, IGUCOMTAG and CNR, Symposium on Geomorphology of Active Tectonic Areas, Cosenza, Italy, June 1990, pp. 67–70. Critelli, S., 1999. The interplay of lithospheric flexure and thrust accommodation in forming stratigraphic sequences in the southern Appennines foreland basin system, Italy. Accademia Nazionale dei Lincei, Rendiconti Lincei Scienze Fisiche e Naturali 257–326 S. 9, 10. Cucci, L., Cinti, F.R., 1998. Regional uplift and local tectonic deformation recorded by the Quaternary marine terraces on the Ionian coast of northern Calabria (southern Italy). Tectonophysics 292 (1–2), 67–83. Diaz, M.C., Torrent, J., 1989. Mineralogy of iron oxides in two soil chronosequences of central Spain. Catena 16, 291–299. Dimase, A.C., Iovino, F., 1996. I suoli dei bacini idrografici del Trionto, Nicà e torrenti limitrofi (Calabria). With 1:100,000 scale map. Accademia Italiana Scienze Forestali, Firenze, Italy, 112 pp. Eriksson, M.G., Olley, J.M., Kilham, D.R., Pietsch, T., Wasson, R.J., 2006. Aggradation and incision since the very late Pleistocene in the Naas River, south-eastern Australia. Geomorphology 81, 66–88. Fedo, C.M., Nesbitt, H.V., Young, G.M., 1995. Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleoweathering conditions and provenance. Geology 23, 921–924. Fedo, C.M., Eriksson, K.A., Krogstad, E.J., 1996. Geochemistry of shales from the Archean (~3.0 Ga) Buhwa Greenstone Belt, Zimbabwe: implications for provenance and source-area weathering. Geochimica et Cosmochimica Acta 60 (10), 1751–1763. Fedoroff, N., 1997. Clay illuviation in red Mediterranean soils. Catena 28, 171–189. Fuller, I.C., Macklin, M.G., Lewin, J., Passmore, D.G., Wintle, A.G., 1998. River response to high-frequency climate oscillations in southern Europe over the past 200 ky. Geology 26 (3), 275–278. Gliozzi, E., 1987. I terrazzi del Pleistocene Superiore della penisola di Crotone (Calabria). Geologica Romana 26, 17–79. Gwendolyn, P., van Balen, R.T., 2007. Pleistocene tectonics inferred from fluvial terraces of the northern Upper Rhine Graben, Germany. Tectonophysics 430, 41–65. Houtgast, R.F., Van Balen, R.T., Bouwer, L.M., Brand, G.B.M., Brijker, J.M., 2002. Late Quaternary activity of the Feldbiss Fault Zone, Roer Valley Rift system, the Netherlands, based on displaced fluvial terrace fragments. Tectonophysics 352, 295–315. Huggett, R.J., 1998. Soil chronosequences, soil development, and soil evolution: a critical review. Catena 32, 155–172. Jain, M., Tandon, S.K., 2003. Fluvial response to the Late Quaternary climate changes, western India. Quaternary Science Reviews 22 (20), 2223–2235. Jo, H.R., Chough, S.K., 2001. Architectural analysis of fluvial sequences in the northwestern part of Kyongsang Basin (Early Cretaceous), SE Korea. Sedimentary Geology 144 (3), 307–334. Knott, S.D., Turco, E., 1991. Late Cenozoic kinematics of the Calabrian Arc southern Italy. Tectonics 10, 1164–1172. Komatsubara, J., 2004. Fluvial architecture and sequence stratigraphy of the Eocene to Oligocene Iwaki Formation, northeast Japan: channel-fills related to the sea-level change. Sedimentary Geology 168, 109–123. Krzyszkowski, D., Stachura, R., 1998. Neotectonically controlled fluvial features, Walbrzych Upland, Middle Sudeten Mts, southwestern Poland. Geomorphology 22, 73–91. Litchfield, N.J., Berryman, K.R., 2005. Correlation of fluvial terraces within the Hikurangi Margin, New Zealand: implications for climate and base-level controls. Geomorphology 68, 291–313. Macklin, M.G., Fuller, I.C., Lewin, J., Maas, G.S., Passmore, D.G., Rose, J., Woodward, J.C., Black, S., Hamlin, R.H.B., Rowan, J.S., 2002. Correlation of fluvial sequences in the Mediterranean basin over the last 200 ka and their relationship to climate change. Quaternary Science Reviews 21, 1633–1641. Maizels, J.K., 1993. Quantitative regime modelling of fluvial depositional sequences: application to Holocene stratigraphy of humid-glacial braid-plains (Icelandic sandurs). In: North, C.P., Prosser, D.J. (Eds.), Characterisation of Fluvial and Aeolian Reservoirs. Geological Society, London, Special Publication, vol. 73, pp. 53–78. Miall, A.D., 1977. A review of the braided river depositional environment. Earth Science Review 13, 1–62. Miall, A.D., 1996. The Geology of Fluvial Deposits: Sedimentary Facies, Basin Analysis and Petroleum Geology. Springer, New York. 582 pp. Ministero delle Politiche Agricole e Forestali (MiPAF), 2000. Metodi di analisi chimica del suolo. Osservatorio Nazionale Pedologico e per la Qualità del Suolo, International

Society of Soil Science, Società Italiana della Scienza del Suolo. Franco Angeli Editore, Milano, Italy, fasciculated. Molin, P., Dramis, F., Lupia, Pal mieri, E., 2002. The Pliocene–Quaternary uplift of the Ionian northern Calabria coastal belt between Corigliano Calabro and Capo Trionto. Studi Geologici Camerti, pp. 135–145. Volume Speciale. Molin, P., Pazzaglia, F.J., Dramis, F., 2004. Geomorphic expression of active tectonics in a rapidly-deforming forearc, Sila Massif, Calabria, southern Italy. American Journal of Science 304, 559–589. Nesbitt, H.V., Young, G.M., 1982. Early Proterozoic climates and plate motions inferred from major elemnt chemistry of lutites. Nature 299, 715–717. Nott, J., Price, D., Nanson, G., 2002. Stream response to Quaternary climate change: evidence from the Shoalhaven River catchment, southeastern highlands, temperate Australia. Quaternary Science Reviews 21, 965–974. Ogniben, L., 1973. Schema geologico della Calabria in base ai dati odierni. Geologica Romana 12, 243–585. Ortiz, I., Simón, M., Dorronsoro, C., Martín, F., García, I., 2002. Soil evolution over the Quaternary period in a Mediterranean climate (SE Spain). Catena 48, 131–148. Pagliarulo, S., 2006. Coastal changes and the environmental evolution of the archeological site of Sybaris (southern Italy). Geografia Fisica e Dinamica Quaternaria 29, 51–59. Palmentola, G., Carotene, L., Mastronuzzi, G., Sansò, P., 1990. I terrazzi marini Pleistocenici della Penisola di Crotone (Calabria). Geografia Fisica e Dinamica Quaternaria 13, 75–80. Pan, B., Burbank, D., Wang, Y., Wu, G., Li, J., Guan, Q., 2003. A 900 k.y. record of strath terrace formation during glacial–interglacial transition in northwest China. Geology 31 (11), 957–960. Ramos, A., Sopeña, A., 1983. Gravel bars in low-sinuosity streams (Permian and Triassic, central Spain). In: Collinson, J.D., Lewin, J. (Eds.), Modern and ancient fluvial systems. Boston, Blackwell Scientific Publ. Special Publication of the International Association of Sedimentologists, vol. 6, pp. 301–312. Oxford, UK. Robustelli, G., Muto, F., Scarciglia, F., Spina, V., Critelli, S., 2005. Eustatic and tectonic control on Late Quaternary alluvial fans along the Tyrrhenian Sea coast of Calabria (south Italy). Quaternary Science Reviews 24 (18–19), 2101–2119. Roda, C., 1964. Distribuzione e facies dei sedimenti neogenici nel Bacino Crotonese. Geologica Romana 3, 319–366. Rossignol-Strick, M., Planchais, N., Paterne, M., 1992. Vegetation dynamics and climate during the deglaciation in the south Adriatic basin from a marine record. Quaternary Science Review 11, 415–423. Russo Ermolli, E., di Pasquale, G., 2002. Vegetation dynamics of southeastern Italy in the last 28000 yr inferred from pollen analysis of a Tyrrhenian Sea core. Vegetation History and Archaeobotany 11, 211–219. Rust, B.R., 1978. Depositional models for braided alluvium. In: Miall, A.D. (Ed.), Fluvial Sedimentology. Canadian Society of Petroleum Geologists. Canadian Society of Petroleum Geologists Memoir, vol. 5, pp. 605–625. Calgary, Alberta. Scarciglia, F., Terribile, F., Colombo, C., Cinque, A., 2003. Late Quaternary climatic changes in northern Cilento (south Italy): an integrated geomorphological and paleopedological study. Quaternary International 106–107, 141–158. Scarciglia, F., Pulice, I., Robustelli, G., Vecchio, G., 2006. Soil chronosequences on Quaternary marine terraces along the northwestern coast of Calabria (southern Italy). Quaternary International 156–157, 133–155. Schiattarella, M., 1998. Quaternary tectonics of the Pollino Ridge, Calabria–Lucania boundary, southern Italy. In: Holdsworth, R.E., Strachan, R.A., Dewey, J.F. (Eds.), Continental Transpressional and Transtensional Tectonics. Geological Society, London, Special Publication, vol. 135, pp. 341–354. Schumm, S.A., 1965. Quaternary paleohydrology. In: Wright, H.E., Frey, D.G. (Eds.), The Quaternary of the United States. Princeton University Press, Princeton, NJ, pp. 783–794. Soil Survey Staff, 2006. Keys to Soil Taxonomy, 10th edit. U.S. Department of Agriculture, Natural Resources Conservation Service, Washington DC. 333 pp. Sorriso-Valvo, M., 1988. Landslide-related fans in Calabria. Catena Supplement 13, 109–121. Sorriso-Valvo, M., 1990. The fill-and-cut sequences in the Trionto river valley, northeast Calabria. In: Sorriso-Valvo, M. (Ed.), IGU-CoMTAG Symposium on Geomorphology of Active Tectonic Areas, Excursion Guide-book, CNR-IRPI, Rende (CS), Italy. Geodata, vol. 39, pp. 71–75. Sorriso-Valvo, M., 1993. The geomorphology of Calabria: a sketch. Geografia Fisica e Dinamica Quaternaria 16, 75–80. Sorriso-Valvo, M., Sylvester, A.G., 1993. The relationship between geology and landforms along a coastal mountain front, northern Calabria, Italy. Earth Surface Processes and Landforms 18, 257–273. Starkel, L., 2003. Climatically controlled terraces in uplifting mountain areas. Quaternary Science Reviews 22 (20), 2189–2198. Steel, R.J., Thompson, D.B., 1983. Structures and textures in Triassic braided stream conglomerates (‘Bunter’ Pebble Beds) in the Sherwood Sandstone Group, north Staffordshire, England. Sedimentology 30, 341–367. Sun, J., 2005. Long-term fluvial archives in the Fen Wei Graben, central China, and their bearing on the tectonic history of the India-Asia collision system during the Quaternary. Quaternary Science Reviews 24, 1279–1286. Tansi, C., Muto, F., Critelli, S., Iovine, G., 2007. Neogene Quaternary strike-slip tectonics in the central Calabrian Arc. Journal of Geodynamics 43, 393–414. Todd, S.P., 1989. Stream-driven, high-density gravelly traction carpets: possible deposits in the Trabeg Conglomerates formation, SW Ireland and some theoretical considerations of their origin. Sedimentology 36, 513–530. Torrent, J., Schwertmann, U., Schulze, D.J., 1980. Iron oxide mineralogy of some soils of two river terrace sequences in Spain. Geoderma 23, 191–208. Torrent, J., Schwertmann, U., Fechter, H., Alfarez, F., 1983. Quantitative relationships between soil color and hematite content. Soil Science 136 (6), 354–358.

G. Robustelli et al. / Geomorphology 106 (2009) 165–179 Tsai, E., Huang, W., Hseu, Z., 2007. Pedogenic correlation of lateritic river terraces in central Taiwan. Geomorphology 88, 201–213. Turco, E., Maresca, R., Cappadona, P., 1990. La tettonica plio-pleistocenica del confine calabro-lucano: modello cinematica. Memorie della Società Geologica Italiana 5, 519–529. Van Dijk, J.P., Bello, M., Brancaleoni, G.P., Cantarella, G., Costa, V., Frixa, A., Golfetto, F., Merlini, S., Riva, M., Torricelli, S., Toscano, C., Zerilli, A., 2000. A regional structural model for the northern sector of the Calabrian Arc (southern Italy). Tectonophysics 324, 267–320. Vezzani, L., 1968. I terreni pliopleistocenici del basso Crati (Cosenza). Atti dell'Accademia Gioenia di Scienze Naturali in Catania 20, 28–84 Serie VI. Vincent, S.J., 2001. The Sis palaeovalley: a record of proximal fluvial sedimentation and drainage basin development in response to Pyrenean mountain building. Sedimentology 48 (6), 1235–1276. Waelbroeck, C., Laberyrie, L., Michel, E., Duplessy, J.C., McManus, J.F., Lambeck, K., Balbon, E., Labracherie, M., 2002. Sea-level and deep water temperature changes

179

derived from benthic foraminifera isotopic records. Quaternary Science Reviews 21, 295–305. Wagner, M., 2005. Geomorphological and pedological investigations on the glacial history of the Kali Gandaki (Nepal Himalaya). GeoJournal 63, 91–113. Wagner, S., Costantini, E.A.C., Sauer, D., Stahr, K., 2007. Soil genesis in a marine terrace sequence of Sicily, Italy. Revista Mexicana de Ciencias Geológicas 24 (2), 247–260. Watts, W.A., Allen, J.R.M., Huntley, B., Fritz, S.C., 1996. Vegetation history and climate of the last 15000 years at Laghi di Monticchio, southern Italy. Quaternary Science Reviews 15, 113–132. Westaway, R., Bridgland, D., White, M., 2006. The Quaternary uplift history of central southern England: evidence from the terraces of the Solent River system and nearby raised beaches. Quaternary Science Reviews 25, 2212–2250. Zecchin, M., Nalin, R., Roda, C., 2004. Raised Pleistocene marine terraces of the Crotone peninsula (Calabria, southern Italy): facies analysis and organization of their deposits. Sedimentary Geology 172 (1/2), 165–185.