Pliocene (?)—early Pleistocene shallow marine deposits, varying from gravel to sand to clay, characterize the southernmost sector of the Valdichiana Basin, between Orte and Città della Pieve, across ...Tuscany, Umbria and Latium (Central Italy). Facies associations, referring to the evolution of a river-fed coast, with a sensible facies heteropy, and a sub-environment articulation, both across and alongshore, have been recently described. Although the main part of the territory responds to a wave-dominated coastal model, a clear fluvial sediment origin and the presence of localized river mouths have also been documented. Nearshore is mainly represented by interbedded sand and gravel beachface to upper shoreface deposits, in which both a mouth bar organization and a lateral distribution of gravel beaches are recognizable. Sediment origins largely depend ondebris flow processes, related to small alluvial fans/fan deltas. In constrained areas, debris flow and current continental deposits occur, referring to coalescent alluvial fans, organized as a smoothly seaward-dipping piedmont band, drained by shallow braided channels. This roughly organized fluvial system feeds a coastal area, with a fandeltabuild-up. The as-described fan delta and beach systems are characterized by a smooth seaward morphology, according to models resembling, on a coast-transverse profile, the shelf-type fan delta. Although the proposed models differ from each other’s, with respect tothe shelf-type one, this is mainly on a lateral facies distribution.
Several terrestrial plant fossils found in the late Cenozoic of Europe belong to thermophilous genera or infrageneric taxa which do not grow in this continent today, and are usually called “exotic ...elements”. Within this large group we singled out three more precisely defined categories based on the hypothesis that the change of geographic distribution between the late Cenozoic and the present is the result of deterministic extinctions caused by climate change. Among the taxa shared by the modern East Asian and the Plio–Pleistocene European flora, the “humid thermophilous taxa of East Asian affinity” (HUTEA) represent the central category in our study. These were traditionally considered “Pliocene” elements in Europe. In our analysis of 13 reliably dated Italian assemblages the percentage of species belonging to the HUTEA category was found to be higher in Pliocene sites, and very low to null in Pleistocene ones. Also early Pleistocene assemblages across all of Europe did not contain any HUTEA, apart from Eucommia, and Symplocos sect. Lodhra in the refugial area of the Colchis.
Our analysis of fruit and seed assemblages in the San Lazzaro section (Umbria, central Italy), recently assigned to the early Pleistocene, provided contrasting evidence, which required a reconsideration of the stratigraphic and palaeontological context of another well known site in central Italy, Cava Toppetti II. Using vertebrate and continental mollusc biochronology the early Pleistocene age of this section was confirmed and its palaeontological records were compared with other assemblages in central Italy and Europe. We show that in central Italy at least three HUTEA species (Sinomenium cantalense, Symplocos casparyi, Toddalia rhenana) persisted after the Pliocene/Pleistocene boundary. We conclude that central-southern Italy offered a refugial niche that was warm and wet enough to assure the longer survival of some HUTEA, in contrast to central Europe.
•we examined the fossil record of extinct plant taxa in Europe persisting in East Asia;•we provided new data about the minimum mean annual temperature tolerated by living East Asian plants;•we showed that the "humid thermophilous plant taxa of East Asian affinity" (HUTEA) have an early Pleistocene record in southern Europe;•our fruit and seed data testify for a stepwise mass extinction of terrestrial plants in southern Europe from 4 to 0.5Ma;•two main collective disappearance events coincide with well-known intervals of major climatic deterioration: 2.7-2.4Ma and 0.9-0.8Ma.
Through time, the wide area between southeastern Tuscany, northeastern Latium, and western Umbria has been revealed as a crucial area for understanding the evolution of Neogene basins in northern ...Apennine. In this study, the results of twenty years of research on the marine early Pleistocene deposits are summarized, and the biological and physical events are presented and discussed in order to propose an integrated stratigraphic scheme. The proposed reconstruction is also included in a wider context, taking into account both the local and regional geological evolution.
Characterization, correlation and provenance determination of tephra samples in sedimentary sections (tephrochronological studies) are powerful tools for establishing ages of depositional events, ...volcanic eruptions, and tephra dispersion. Despite the large literature and the advancements in this research field, the univocal attribution of tephra deposits to specific volcanic sources remains too often elusive. In this contribution, we test the application of a machine learning technique named Support Vector Machine to attempt shedding new light upon tephra deposits related to one of the most complex and debated volcanic regions on Earth: the Pliocene-Pleistocene magmatism in Italy. The machine learning algorithm was trained using one of the most comprehensive global petrological databases (GEOROC); 17 chemical elements including major (SiO2, TiO2, Al2O3, Fe2O3T, CaO, MgO, MnO, Na2O, K2O, P2O5) and selected trace (Sr, Ba, Rb, Zr, Nb, La, Ce) elements were chosen as input parameters. We first show the ability of support vector machines in discriminating among different Pliocene-Pleistocene volcanic provinces in Italy and then apply the same methodology to determine the volcanic source of tephra samples occurring in the Caio outcrop, an Early Pleistocene sedimentary section located in Central Italy. Our results show that: 1) support vector machines can successfully resolve high-dimensional tephrochronological problems overcoming the intrinsic limitation of two- and three-dimensional discrimination diagrams; 2) support vector machines can discriminate among different volcanic provinces in complex magmatic regions; 3) in the specific case study, support vector machines indicate that the most probable source for the investigated tephra samples is the so-called Roman Magmatic Province. These results have strong geochronological and geodynamical implications suggesting new age constraints (1.4 Ma instead of 0.8 Ma) for the starting of the volcanic activity in the Roman Magmatic Province.
•Machine learning techniques have been applied for tephrochronological studies.•Support vector machines discriminate among different volcanic provinces.•Support vector machines show a Roman geochemical affinity for the studied tephra.•Results antedate the starting activity of the Roman Magmatic Province to ca. 1.4 Ma.
Although drillholes in modern and ancient ostracods are known, the record is relatively scarce when compared to other taxa, and mainly exist with reference to the marine environment. Moreover, less ...is known about perforated ostracods, and more generally, about bioerosion in freshwater environments. Traces of predation on freshwater ostracods are reported for the first time in deep-lake deposits belonging to the early Pleistocene Fosso Bianco Unit, and outcropping in the Cava Nuova section (Umbria, central Italy). Deposits are mainly clay to silty clay and sand; the fossil record is sparse, and is mainly comprised of very rare gastropods and bivalves, ostracods and plant remains (leaves, seeds and wood’s fragments). The association of ostracods consists of Candona (Neglecandona) neglecta, Caspiocypris basilicii, Caspiocypris tiberina, Caspiocypris perusia, Caspiocypris tuderis, Caspiocypris posteroacuta, and Cyprideis torosa. The Caspiocypris group, considered to be endemic to the grey clays of the Fosso Bianco Unit, present the majority of specimens affected by predation, with a prevalence of predated female valves and a comparable number of right and left predated valves, while only a few of Candona(N.) neglecta (adult and juvenile) valves are perforated. Traces of predation for nourishment, represented by microborings of different types, were abscribed to the ichnospecies Oichnus paraboloides Bromley 1981, Oichnus simplex Bromley 1981, Oichnus gradatus Nielsen and Nielsen 2001, Oichnus ovalis Bromley 1993, and Dipatulichnus rotundus Nielsen and Nielsen 2001. Microboring affected both adult and juvenile specimens, evidencing prey–predator coexistence in the same environment over a long period of time. This report makes a fundamental contribution to the knowledge of predation in this peculiar confined environment, also suggesting prey–predator relations over a relatively short time interval (80–160 ka).
The application of Ground Penetrating Radar (GPR) prospecting to the search of fossil structures, particularly using advanced techniques like Finite-difference time-domain (FDTD) modelling and GPR ...attribute analysis, is currently poorly exploited in paleontology. Here, we promote the use of such a GPR workflow at Bargiano (Umbria, central Italy), a unique paleontological site known for the discovery of cetacean skeletons, dolomitized sperm-whale cololites (Ambergrisichnu salleronae), and layered fossil assemblages. The study site is characterized by a very uneven topography shaping highly conductive clayey deposits, representing not exactly ideal conditions for GPR surveying. After generating models encompassing a real topography and variable electrical properties of media, we simulated buried fossil structures at variable depth with different size and geometry, using different operative frequencies. After obtaining information on the characteristics of reflections, investigation depth, and detectability, we provide a comparison with experimental data, also used to compute instantaneous amplitude and phase attributes. Upon depicting a peculiar GPR signature for our targets, we discuss the results in light of ground-truthing performed through trenching. Our workflow allowed us to restrict the excavation areas, extending the surface information in depth in a non-invasive way, and optimizing the field operations, necessary for the preservation of the study site.
Early Pleistocene marine deposits in southwestern Umbria (Orvieto–Allerona area, Italy) recently revealed the presence of more than forty carbonate conduits distributed over 2 km along the Paglia ...riverbed. In order to investigate their origins, analyses of their mineralogy, δ18O and δ13C stable isotopes, and organic geochemistry were conducted. All the carbonate conduits are made of euhedral microcrystals of dolomite with subordinate quartz, plagioclases, and micas. The stable carbon and oxygen isotope values of the bulk concretionary carbonates range from −0.57 to +4.79‰ (δ13C) and from +1.58 to +4.07‰ (δ18O), respectively. The lack of organic geochemical biomarkers of anaerobic methane oxidation (AOM) and the very low values of extractable organic matter suggest a non-biological origin for the dolomite precipitation. The latter is probably related to the rise of volcanic carbon dioxide due to the incipient Vulsini magmatism recorded in Early Pleistocene marine deposits all around the study site. The spatial distribution of the structures indicates that the upward migration of the CO2 was controlled by the fault system, while the vertical development of the conduits suggests that carbon dioxide degassing occurred, with multiple events. Carbon dioxide was probably stored in pockets within the clayey sediments until the pressure exceeded the eruptive threshold. These structures represent the first documentation of a volcanic carbon dioxide marine seepage event in the Umbria region.
The historical Camerano town (Ancona, Central Italy), built on the top of a hill at the rear of the Conero Mt. promontory, holds a broad underground system of remarkable man-drilled caves. Contrary ...to the roughly total lack of subaerial accessible outcrops, the caves allow to reconstruct the geological evolution and to describe a composite sedimentological and stratigraphic section into Early Pleistocene (Calabrian) marine deposits. The present study is aimed to a better definition of the sedimentological and palaeoenvironmental context for the Camerano area, and also improves the knowledge of the Camerano caves. Sediments are mainly regarded as massive to laminated yellow-brown bioclastic sand and massive grey-green clay couplets, variable in thickness, each couplet showing erosive basal surface and normal gradation, from sand to clay. Plane-parallel lamination, marked by recurring variations in grain size, is referred to “traction carpets”, and the sand horizons are described as carbonatic turbidites with eastern supply (Conero Mt.). Conversely, clay reflects both western river deltas distal supply and local contribution from marine productivity. Along the section, matrix-supported gravel beds also occur made of heterometric clay fragments dispersed into a bioclastic sandy matrix. Described facies only partially insert in the former geological schemes, and offer new insights to the palaeoenvironmental restoration for the Camerano area, which involves a tectonically active Early Pleistocene basin, mainly dominated by clay sedimentation, periodically reached by storm- to seismic-induced carbonatic turbidites. The large clay fragments, matrix-supported gravels probably derive from remobilization of partially lithified deposits along the basin’s flank and represent the distal evolution of west- coming slumps.
A new ostracod association, referred to the Early Pleistocene on the basis of the nannoplancton analysis, is studied and described. It comes from the so-called “Agira marls” outcropping in contrada ...Santa Venera, SW of the Agira town (Central Eastern Sicily). The ostracod fauna is composed by 39 species, 11 species being here proposed and described as new: Eucytherura sanctavenerae n. sp., Aurila seguenzai n. sp., Aurila diodoroi n. sp., Cimbaurila ramdohri n. sp., Tenedocythere eleonorae n. sp., Loxoconcha pokornyi n. sp., Paracytheridea longicristata n. sp., Cistacythereis oertlii n. sp., Costa agyrina n. sp., Echinocythereis hartmannii n. sp. and Tegmenia mariasophiae n. sp. The remaining are known species or left in open nomenclature.
Une nouvelle association d'ostracodes, attribuée au Pléistocène inférieur grâce à une analyse du nannoplancton, est étudiée et décrite. Elle provient de la marne dite d'Agira, au sud-ouest de la ville du même nom (Sicile Centro-orientale). L'association est composée de 38 espèces, 11 espèces sont ici proposées et décrites comme nouvelles : Eucytherura sanctavenerae n. sp., Aurila seguenzai n. sp., Aurila diodoroi n. sp., Cimbaurila ramdohri n. sp., Tenedocythere eleonorae n. sp., Loxoconcha pokornyi n. sp., Paracytheridea longicristata n. sp., Cistacythereis oertlii n. sp., Costa agyrina n. sp., Echinocythereis hartmannii n. sp. et Tegmenia mariasophiae n. sp. Les autres sont des espèces connues ou laissées en nomenclature ouverte.
PDF
