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F. Marra et al. / Earth-Science Reviews 139 (2014) 104–122 107 ISOTOPIC STAGES AGGRADATIONAL FAUNAL UNITS SELECTED LOCALITIES 18 δ O (‰) UNITS OF THE ROMAN BASIN 3.5 2.5 2.0 4.0 in italics: sections without chronostratigraphic correlation 3 in bold: newly assigned 0 *selected localities of the larger Latium area Milli 2008 et al., 2.2 TI Recent alluvial deposits 13.6±0.2 INGARANO 5.3 100 200 300 400 500 600 700 800 900 MELPIGNANO 5.5 6.2 TII Epi-Tyrrhenian Formation -? Sacco Pastore 7.3 7.5 8.2 254±8 TIII Vitinia Formation PG7 Vitinia, Cerveteri*, Torre in Pietra 2, Casal de’ Pazzi 269±5 8.5 VITINIA 288±6 Via Mascagni parasequence Sedia del Diavolo, Monte delle Gioie 9.3 10.2 Torre in Pietra 1 (=Torre del Pagliaccetto), Malagrotta, TIV Aurelia Formation PG6 TORRE IN PIETRA La Polledrara di Cecanibbio, Castel di Guido Km 19 and 20, Collina Barbattini, Prati Fiscali, Riano Flaminio*, Cretone* 367±4 11.1 412±2 Age (ka) TV 12.2 427±5 San Paolo Formation PG5 FONTANA RANUCCIO Fontana Ranuccio* San Cosimato, Fontignano 2 440±8 13.1 490±4 499±3 496±9 510±4 13.3 Valle Giulia Formation Cava Rinaldi, Cava Nera Molinario, Monte Antenne, 517±6 PG4 14.2 22.2 TVI Villa Glori, Parioli 534±2 15.1 592±8 Malafede parasequence 615±3 611±6 15.5 16.2 TVII ISERNIA Santa Cecilia Formation PT4 PG3 Cava di Breccia Casale Selce (u.l.), Maglianella 653±4 Vitinia gravels 17.3 18.2 TVIII PG 2B Formation PONTE GALERIA 18.3 PT3 PG2 Cava di Breccia Casale Selce (l.l.) 18.4 PG 2A Formation 763±8 19.3 20.2 TIX 788±9 PG 1 Formation PT2 PG1 SLIVIA Fontignano 1, Cava Redicicoli (1) 808±6 21.5 TX Monte Ciocci Formation PT1 PG0 Fig. 3. Recognition of the stratigraphic position within the geochronologically constrained aggradational units of the fossiliferous localities of the Roman basin provides their correlation with the δ18Oisotopicrecord(Lisiecki and Raymo, 2005). Horizontal lines are the age constraints derived by the 40Ar/39Ar dating of the volcanic deposits intercalated within the aggra- dational units of the paleo-Tiber River shown in Fig. 2. Each shaded box individuates a period of sea-level rise that accounts for the deposition of the sedimentary successions in the coastal area of Rome. (1) The possible occurrence of a distinct, later faunal assemblage in the upper levels of Cava Redicicoli (Di Stefano et al., 1998) is discussed in the text (see also Fig. 4). 3. Eustatic forcing on the stratigraphic record Therefore, in the text we will associate the sedimentary units to a pair of MIS (e.g., MIS 20–19). Several studies (Marra and Florindo, 2014 and references therein), Generally, the aggradational sections recognized in Ponte Galeria are have shown that glacio-eustatic forcing controlled deposition of sedi- fining-upward sequences, with coarse-grained gravel and sand, up to mentary sections in the coastal plains of the paleo-Tiber River and in 10 m in thickness, overlying the erosional base of each section. The the alluvial plains of its tributaries near Rome. Using 40Ar/39Ar ages of coarse-grained deposits are followed by a relatively thin (1–2m)sand tephra layers intercalated with the sedimentary deposits and paleomag- horizon, which grades upward into a several meters thick package of netic measurements on clay horizons it was demonstrated that the sed- silt and clay. In the older sections, deposited during MIS 22–21 through imentary sections were deposited during sea-level rises and associated MIS 16–15, these clay intervals have moderate thickness (b10 m), prob- marine ingressions following the glacial terminations (Karner and ably as a consequence of the lower amplitude sea-level oscillations asso- Marra, 1998; Karner and Renne, 1998; Marra et al., 1998; Florindo ciated to these early glacial cycles (Karner et al., 2001b). In contrast, a et al., 2007). The stratigraphic record of each complete glacially forced significant increase of the clay section is observed in the younger suc- sea-level oscillation in a coastal area is represented by a basal erosive cessions (e.g., San Paolo Formation, MIS 11; Karner and Marra, 1998), surface, progressively excavated as a consequence of lowering of sea up to that of the modern Tiber River, which reaches 70 m in thickness level during glacial periods, overlain by a succession of clastic sediments within the present-day coastal plain (Marra et al., 2013). and rapidly deposited during sea-level rise in response to deglaciation. Radiometric age constraints on the sedimentary record deposited The geochronologic constraints in the whole area of Rome spanning within the valley and in the coastal plain of the modern Tiber River the Middle Pleistocene to the Holocene evidenced that the sedimentary (Marra et al., 2008, 2013) demonstrate that the rapid accumulation of transition from gravel to clay corresponds to a glacial termination and gravel marks a unique time in the depositional history of the river, oc- thus to the transition between an odd and an even isotopic stage. curring during an ~7 kyr interval between the end of the Last Glacial 108 F. Marra et al. / Earth-Science Reviews 139 (2014) 104–122 Maximum (LGM; ~21 ka, Bard et al., 1990) and the last glacial termina- lowstand period at the onset of the abrupt climatic change leading to tion (T-I; ~14 ka, Stanford et al., 2006). Indeed, the transportation by the a warmer climate and rise in sea level. The main portion of these clay Tiber River of gravel with diameters of the pebbles N5 cm required ex- sections was deposited during the high-stand, within lagoonal or coast- ceptional hydrologic conditions that have not been repeated during al environments, as shown by the faunal assemblage of the ‘Venerupis Holocene time. These conditions are possible only during a glacial ter- senescens clay’ (Conato et al., 1980) or the ‘Santa Cecilia clay’ (Karner mination due to the combination of several factors, such as increased and Marra, 1998), deposited during the high stands of MIS 17 and MIS sediment supply to the Tiber drainage basin, increased regional rainfall, 15, respectively. However, continental deposits associated to the transi- low sea level causing a steeper gradient. These conditions would have tion between interglacial and glacial periods may occur in the near- worked in concert during the 21 ka–14 ka interval, until the accelerated coast area as a consequence of the regressive phases, in particular as rise in sea level during the glacial termination led to a rapid drop in eolian deposits and, to a lesser extent, as lacustrine–palustrine ones. competence of the Tiber River and, consequently, to the start of sandy In the present work, we correlate the deposits in which the recog- clay deposition. nized faunal assemblages occur to the aggradational sections identified in the Ponte Galeria area. Based on this approach, any fossil that can be 4. Materials and methods referred to an identified geochronologically constrained sedimentary unit can be assigned a discrete age, corresponding to that of the associ- 4.1. The mammal remains from Ponte Galeria area ated MIS (Fig. 3). Identification of the glacio-eustatically forced sedimentary units can The studied material is presently housed in two collections, one in be achieved by: the Museum of Paleontology, Sapienza University of Rome (MPUR), the other in the Soprintendenza Archaeologica of Rome (SAR). Most of (1) literature data: whenever the outcrop corresponds to published the paleontological specimens were collected from several quarries type sections; localized in the area since the beginning of the second half of the (2) stratigraphic context: whenever the stratigraphic position of the 20th century and were published by Blanc et al. (1951), Ambrosetti outcrop with respect to other dated sections is determinable; (1965, 1967), Caloi and Palombo (1978, 1980a,b, 1986), Caloi et al. (3) recognition of pyroclastic deposits of known age within the (1980a,b,c, 1981), Capasso Barbato and Petronio (1981, 1983), outcrop; Capasso Barbato et al. (1983), Petronio (1986), Di Stefano and (4) identification of the age of pyroclastic material occurring in the Petronio (1993, 1997) and Petronio and Sardella (1998, 1999). Other strata or conglobed in the fossil, by means of: considered specimens housed in the MPUR were collected during the (1) petrographic analysis of thin section, or end of the 19th century around and within the city of Rome; they (2) laboratory geochemical analysis (e.g., glass composition, trace were mostly published by Blanc, Clerici, De Angelis d'Ossat, Maxia, element ratios), allowing at correlate the deposit with known, Meli, Ponzi, Portis and Tuccimei (for details see references in Kotsakis dated products; and Barisone, 2008). A few remains housed at MPUR have been never (3) direct radiometric dating (40Ar/39Ar). published in previous works on the area and are shortly described in the next chapter. 5. The Ponte Galeria area The revised Quaternary time scale (Gibbard et al., 2010)for chronostratigraphy and geochronology is followed in this paper. The 5.1. Stratigraphy of Ponte Galeria area biochronology of mammals follows schemes reported by Gliozzi et al. (1997) for Italy and later modified by Petronio and Sardella (1999) Three aggradational successions deposited in the time span between and Petronio et al. (2011). 800 and 600 ka have been identified in the Ponte Galeria area: PG1, PG2, and Santa Cecilia formations (Marra et al., 1998). These correspond 4.2. Method of correlation of the faunal assemblages with the aggradational only in part to the fourth-order sequences described by sequence- successions stratigraphic work in this area (e.g., Milli et al., 2008), as illustrated in this section.