Middle Pleistocene Vertebrate-Bearing Fluvial Deposits of the Ceriti Mts Area, Latium Coast (Central Italy)
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Geologica Romana 39 (2006), 27-38 MIDDLE PLEISTOCENE VERTEBRATE-BEARING FLUVIAL DEPOSITS OF THE CERITI MTS AREA, LATIUM COAST (CENTRAL ITALY) Marco Mancini1, Maria Rita Palombo2,1, Carmelo Petronio2,1, Raffaele Sardella2,1, Claudia Bedetti3, Luca Bellucci4, Emanuele Di Canzio3, Caterina Giovinazzo5, Mauro Petrucci6 and Flavia Trucco7 1 CNR Istituto di Geologia Ambientale e Geoingegneria, Via Bolognola 7, 00138 Rome, Italy e-mail: [email protected] 2 Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza”, P.le A. Moro 5, 00185 Rome 3 Collaboratore scientifico esterno c/o Dipartimento di Scienze della Terra, Università di Roma “La Sapienza” 4 Dottorato di Ricerca in Paleontologia, consorzio tra Università di Modena e Reggio Emilia, di Bologna e di Roma “La Sapienza” 5 Dottorato di Ricerca in Scienze della Terra, Università degli Studi di Roma “La Sapienza” 6 Dottorato di Ricerca in Scienze della Terra, Università degli Studi di Torino 7 Soprintendenza Archeologica per l’Etruria meridionale ABSTRACT - It is here presented a Middle Pleistocene fossiliferous site, the Cerveteri Monte Li Pozzi (CMLP) site, located in the Ceriti Mts area, within the wider Roman Basin (Latium coast, central Italy). The outcropping succession is, from base to top, composed of terrigenous and carbonate fluvial deposits, travertines and ~ 410 ka old pyroclastites. The fluvial deposits form an aggradational river terrace, belong to an ancient risen alluvial-coastal plain and sedimented close to the palaeocoast. Two fossiliferous levels have been discov- ered inside: the lower level, where Elephas (Palaeoloxodon) antiquus and Axis sp. ? A. eurygonos were found; the upper level with E. antiquus, Stephanorhinus cf. S. hundsheimensis, Dama cf. D. clactoniana, Arvicola mos- bachensis, Testudo sp.. The faunal assemblage as a whole indicates the middle-late Galerian Mammal Age, approximately 600-500 ka, and may be correlated with the MIS 15 or MIS 13. This fossil assemblage is the first discovery of Galerian fauna in the Ceriti Mts area and thus represents a new Local Fauna. On the basis of lithostratigraphic, biochronologic and elevation data, it is possible to estimate an approximate- ly 0.26 mm/a uplift rate in the Ceriti Mts basin. KEY WORDS: Middle Pleistocene, Italy, fluvial deposits, mammal fossil assemblage, uplift. INTRODUCTION faces of the terraces are widely used to estimate the rate Ancient fluvial deposits forming aggradational river of uplift along the Latium coast (Karner et al., 2001a; terraces can be used as markers of uplift (Maddy, 1997; Giordano et al., 2003; De Rita et al., 2002). Finally, sev- Van den Berg & Van Hoof, 2001; Westaway, 2001), in eral vertebrate-bearing fossiliferous sites have been dis- particular if sedimentation took place close to palaeo- covered within the fluvial-deltaic and coastal sediments coasts (Burbank & Anderson, 2001). In many cases of the Roman Basin (Milli et al., 2004; Milli & Palombo, these deposits are interbedded with shallow marine and 2005). transitional sediments or with volcanites, in general It is here presented a new site of palaeontologic and chronologically well constrained by biostratigraphy or biochronologic interest, the Cerveteri-Monte Li Pozzi radiometric age data. Moreover, fluvial deposits com- site (CMLP site hereafter), where terraced fluvial monly bear vertebrate fossil remains (Bridge, 2003), deposits crop out, more than 3 km inland from the pres- which may constitute local assemblages of biochrono- ent-day coastline and some 5 km NW from Cerveteri logic relevance and may be used as correlation tool with (Fig. 1). Paleontologic, sedimentologic and elevation marine isotope stages (Bridgland & Schreve, 2001). data of fluvial sediments are used to provide information These three conditions, presence of river terraces, on chronostratigraphy and paleoenvironmental aspects interlayering of fluvial deposits with marine ones and of the site and on local uplift. volcanites, and occurrence of faunal assemblages in river sediments are present in many Italian Neogene- Quaternary sedimentary basins and in particular in the METHODS Roman Basin, along the eastern Tyrrhenian Sea coast (Latium Region) (Fig. 1). Here, in fact, the basin fill is The CMPL palaeontologic site corresponds to an exca- partly composed of terraced fluvial deposits interbedded vation conducted by the “Soprintendenza Archeologica with coastal marine, volcanic and volcano-sedimentary per l’Etruria meridionale” in collaboration with the successions (Conato et al., 1980; Milli, 1997; Karner & Università degli Studi di Roma “La Sapienza” and CNR- Marra, 1998). Moreover, elevation data from top sur- Istituto di Geologia Ambientale e Geoingegneria. The 28 Geologica Romana 39 (2006), 27-38 MANCINI et al. A P E N 14 N Lake Sabatini IN Tolfa Mts Bracciano N Tolfa Mts Mts E S Ceriti 1 Ceriti 12 13 MMtsts 4 10 teri 9 11 erve 2 5 Fig. 3a C 3 Rome 6 7 8 r ive Alban I er R ta Tib ROMAN Hills ly BASIN T y Rome r rh 42¡ 15 e LATIUM 16 n ia 17 n S e 38¡ 10 km a 12¡ 16¡ 1 Selected fossiliferous sites: 9 ) Monte Mario 1) Cerveteri-Monte Li Pozzi 10) Sedia del Diavolo 2 2) Torre in Pietra 11) Saccopastore 3) Castel di Guido 12) Cava Nera Molinario 3 4) Polledrara 13) Redicicoli 4 5) Malagrotta 14) Capena 6) Ponte Galeria 15) Fontana Ranuccio 5 7) San Cosimato 16) Isernia-La Pineta 8) Vitinia 17) Notarchirico Fig. 1 - Simplified geological map of the Roman Basin, with location of selected fossiliferous sites. Legend: 1) subaeral volcanic and volcano-sed- imentary successions (Late Pliocene-Late Pleistocene); 2) marine and non-marine sedimentary successions (Late Miocene-Holocene); 3) marine, car- bonate and siliciclastic successions (Trias-Middle Miocene); 4) normal fault; 5) buried normal fault. excavation is located on the eastern flank of Monte Li fronts perpendicular to it. This good exposure enables Pozzi, a N-S oriented hill with planar top surface at 136 physical stratigraphic analysis and 3D facies reconstruc- m a.s.l., at the interfluve between Fosso Sassetara to the tion to be made (Fig. 2), as well as collection of fossil east and Fosso Perazzetta to the west. The excavation is remains and preliminary taphonomic observations. rectangular in plan view and presents two floors, at 118 Facies analysis has been conducted following the stan- and 121 m, separated by a major step. Each floor corre- dard methods of field geology (Miall, 1996; 2000). In sponds to a fossiliferous level. The main front of the exca- particular for terrigenous fluvial deposits it has been fol- vation is 7 m in length and is oriented N20°E, with minor lowed in part the Architectural Element Analysis of Miall (1996), while environmental models of calcareous tufa from Pedley (1990) have been considered for facies analysis on travertines. GEOLOGICAL FRAMEWORK The Roman Basin and the northern-central Latium coastal belt The Roman Basin widens for more than 70 km in the NW-SE direction along the coastal region of Latium and is of tectono-sedimentary origin. It was formed after the SW-NE directed extension that affected the western mar- gin of the northern-central Apennines since Late Miocene, in concomitance with the opening of the backarc Thyrrenian Sea Basin (Funiciello & Parotto, 1978; Malinverno & Ryan, 1986; Patacca et al., 1990; Fig. 2 - Cerveteri Monte Li Pozzi site: view of the excavation. A-E are the facies described in the text and featured in fig.4. Bar scale is 2 m Cavinato & De Celles, 1999). The Roman Basin is sub- in height. divided into horsts and minor grabens or half-grabens, MIDDLE PLEISTOCENE VERTEBRATE-BEARING FLUVIAL ... Geologica Romana 39 (2006), 27-38 29 mainly bounded by NNW-SSE and NE-SW trending 1994a,b) is of great interest for reconstructing the normal faults. Pliocene and Pleistocene sedimentologic, volcanic and The fill of the Roman Basin (Funiciello & Parotto, tectonic evolution of northern Latium. This basin is 1978; Barberi et al., 1994; Funiciello, 1995; Marra et al., located in the north-westernmost margin of the Roman 1995), only considering sedimentary successions, is Basin and comprises the CMLP fossiliferous site (Figs. composed of: 1) at the base, Lower Pliocene to Lower 1 and 3a). Pleistocene sequences, of shelf marine and coastal envi- Morphologically, the Ceriti Mts area is a hilly region ronments and up to 1 km in thickness. They cover with with maximum elevation of 430 m a.s.l. and is elongat- angular unconformity syn-orogenic, Meso-Cenozoic ed in the NNW-SSE direction. This area is bounded to successions and recorded phases of tectonic subsidence, the west by a narrow coastal plain, no more than 2 km interrupted by short-term phases of localised uplift. 2) wide and with inner margin at about 15 m a.s.l. The plain Middle Pleistocene to Holocene fluvial, coastal and shal- is laterally contiguous to the Tiber River delta plain to low marine sediments, which were deposited under a the SSE. The present-day river drainage in the Ceriti Mts tectonic regime of regional uplift. area is represented by short streams roughly flowing in Furthermore, in northern and central Latium a wide- the NNE-SSW direction. spread, subaeral volcanism developed at different time In the hilly area two main belts are recognised: 1) an intervals: Late Pliocene, late Early Pleistocene and eastern belt, which is characterised by an almost N-S Middle-Late Pleistocene (Locardi et al., 1977; Barberi et directed alignement of acid lava domes, Late Pliocene in al., 1994; Cavinato et al., 1994; Funiciello, 1995; Marra age (De Rita et al., 1994a); 2) a western belt, where three et al., 1998; Karner et al., 2001b). This volcanism is main morphological terraces are recognised and which mainly represented by pyroclastic products, interbedded border the coastal plain. These terraces correspond to with the sedimentary sequences. Related magmatism, as depositional surfaces, gently dip seaward and are sepa- a whole, locally enhanced the regional trend of uplift.