The thick upper Pliocene to lower Pleistocene succession of hemipelagic mudstones of the Marche Apennines foredeep (central Italy) is punctuated by several mostly coarse-grained, cyclic turbidite systems. Integrated and detailed analyses of sedimentary facies, physical stratigraphy, biostratigraphy, and magnetostratigraphy have provided a high-resolution sequence stratigraphic framework for sediments of two of these coarse-grained systems, each resulting from the stack of five deepwater, high-frequency depositional sequences backfilling the mouth and lower reaches of a long-lived submarine canyon. The tight chronostratigraphic control available on these two turbidite systems and encasing hemipelagic sediments allows a precise correlation of the component high-frequency sequences with the Pliocene marine oxygen isotope curve. This reveals that the cyclic arrangement occurred near the Gauss-Matuyama polarity transition and the onset of the Olduvai subchron in response to recurring, obliquity-driven global changes in sea level. Each depositional sequence, 20 to 65 m thick, includes sediments that were deposited by a range of gravity-driven processes, resulting in sedimentary motifs that contain a deep marine record of both glacial and interglacial stages. A typical depositional sequence comprises: (1) a lowstand systems tract composed of cohesionless-debris-flow conglomerates (braided submarine channel complex), which passes down-dip into turbidite sandstones (frontal-splay complex); (2) an overlying transgressive to early falling-stage systems tract composed of a mud-rich mass-transport complex of slumped horizons and cohesive-mud-flow pebbly mudstones eventually overlain by a thin interval of hemipelagic mudstones. This stacking pattern records variations in depositional style, and hence, variations in canyon activity during eustatic changes in sea level.

We report the first record of the bivalve Portlandia impressa from Pleistocene sediments of Marche. The finding is represented by a few shells retrieved from inner shelf deposits exposed at Grotti, in the municipality of Montefiore dell'Aso (Ascoli Piceno). The sediments that yielded the fossils belong to the upper part of the Marchean Quaternary marine sequence (Qm), here referred to the Early Pleistocene. In particular, the integration among foraminifer, calcareous nannoplankton, and mollusk data supports an Emilian age for the fossiliferous level. This record extends the chronostratigraphical range of the Early Pleistocene boreal affinity species P. impressa, traditionally retained Santernian in age. From the paleoecological point of view, the comparison among the very few mollusk assemblages containing P. impressa enables us to retain this fossil protobranch as a tolerant pelophilous taxon that inhabited inner-shelf soupy bottoms. RIASSUNTO - (Prima segnalazione del bivalve ad affinita boreale Portlandia impressa nell'Emiliano di Montefiore dell'Aso (Marche, Italia)) - Portlandia impressa e un raro bivalve finora segnalato esclusivamente nel Pleistocene inferiore del bacino Padano: Valle dello Stirone (Parma) e Val Chero (Piacenza). Tradizionalmente la sua distribuzione stratigrafica e limitata al Santerniano ed anche se non puo essere annoverato tra i veri ospiti nordici (essendo la specie endemica del Mediterraneo) il genere condivide tuttavia il carattere boreale di questo gruppo di taxa. Nel presente lavoro viene segnalata per la prima volta la presenza di Portlandia impressa nel Pleistocene delle Marche. I sedimenti che contengono questa specie affiorano in localita Grotti (Montefiore dell'Aso, Ascoli Piceno) e sono costituiti da argille siltose completamente bioturbate deposte in ambiente di piattaforma interna. Essi rappresentano i depositi litorali regressivi (RLD) che caratterizzano la parte sommitale della successione marina del Quaternario delle Marche (Qm). L'integrazione dei dati biostratigrafici basati sui microfossili, foraminiferi e nannoplancton calcareo, con quelli ottenuti dai sopravvissuti pliocenici tra i molluschi permette di riferire tali depositi all'Emiliano, estendendo in tal modo il range cronostratigrafico finora conosciuto (Santerniano) di P. impressa, basato su un unico riferimento. La malacofauna, composta da 39 taxa di cui 18 bivalvi, 19 gasteropodi e 2 scafopodi, rappresenta una paleocomunita a Venus multilamella instaurata su un substrato fangoso. La non applicabilita di metodologie quantitative non consente un preciso riferimento alla profondita che comunque rimane con tutta probabilita inquadrabile nell'ambito dell'infralitorale. Questo dato appare in buon accordo con quello fornito dall'associazione a foraminiferi. La comparazione della malacofauna nel suo complesso con quelle associate agli altri scarsi rinvenimenti di P. impressa, consente di ritenere questo taxon una forma pelofila tollerante che popolava ambienti di piattaforma interna.

A detailed geological survey and 140 stratigraphic logs carried out for the executive design of the double track variant of the Ancona-Bari railway between the Ortona and Casalbordino stations allowed a stratigraphic section to be compiled, extending 29 km from NW to SE. The study area is part of the Marche-Abruzzi sector, between Ancona and the Sangro River, of the Periadriatic foredeep (or Periadriatic basin) between the Apennine chain and the central Adriatic Sea foreland. This area consists of the Late Pliocene p.p.-Early Pleistocene shelf sediments (Qm depositional sequence; CANTALAMESSA et alii, 1986; ORI et alii, 1991; BIGI et alii, 1995), the Early Pleistocene Qml sequence and the Middle-Late Pleistocene Qcl and Qc2 or Qc sequences of coastal to continental environment. The outcropping succession consists of shelf pelitic-sandy deposits, corresponding to the Qm sequence, followed by yellow sands characterised by the alternation of foreshore and shoreface facies of the Qm1 sequence. This sequence shows a rather complex organization, strongly conditioned also by the substratum paleomorphology. The lower and medium-upper parts of the Qm1 sequence are the prevailing lithofacies in the southern sector and in the most northern sector of the stratigraphic section, while in the central-northern sector fluvio-deltaic conglomerates and shelf and lagoon pelitic-sandy deposits are intercalated in the yellow sands with unconformable boundaries. The two units are separated by a 7° unconformity. Fluvial-deltaic gravels with calcareous Mesozoic clasts, related to the Qc sequence, cap the top succession. Therefore the whole succession shows a clear coarsening upward trend in a general regressive context related to the Emilian regression (RUGGERI, 1980). This tectonic activity continued also during deposition of the Qml sequence, as testified by the 5° unconformity recognized between the yellow sands and the intercalated pelitic-sandy deposits. Infact, from the drillings data at least six depositional sequences of lower rank, pointed out by marked facies contrasts, can be recognized in the inner of the Qml sequence. Surface geological surveying and facies analysis indicate a rather complex organization of the depositional units and a high frequency cyclicity (BIGI et alii, 1997; AMOROSI et alii, 1998; CANTALAMESSA u0026 DI CELMA, 2004). The low resolution of the drilling logs did not allow the organization of the systems tracts of the sequence to be solved, but the recognized unconformities allow some allostratigraphic units to be defined, a result very useful for geological cartographic purposes. Values of the strontium isotopic ratio calculated on bivalve shells sampled in the pelitic-sandy deposits intercalated in the yellow sands indicate a 0,9-1.6 Ma age. This age corresponds to a wide chronological interval, but the presence of the Small Gephyrocapsa biozone (MNN19e in Rio et alii, 1990) of Early Pleistocene (Sicilian) suggests that this interval can be reduecd to 1.25-0.98 Ma. It follows that the 7° unconformity, as recognized in the neighbouring southern Vasto area too, between the yellow sands and the pelitic-sandy deposits is Sicilian. The unconformity is due to sinsedimentary tectonic events, in turn connected to the compressive tectonic phases of the structures west of the study area (CASNEDI et alii, 1981; VEZZANI u0026 GHISETTI, 1988). Dating of the lithostratigraphic units by values of the strontium isotopic ratio is a particularly significant result since it has supplied chronostratigraphic information that integrated the scarce biostratigraphic resolution.

This study summarises the results of a geological survey carried out in the Monte San Vicino-Cingoli area of the Umbria-Marche Apennines. In this area, the axial culmination of the external Apennine ridge and the widespread occurrence of Messinian and Pliocene deposits provide an almost complete record of the deformation history of the external zones of the chain. The prosecution of the Sibillini Thrust North of the Chienti River valley, never previously ascertained, has been identified within the Miocene units exposed in the western limb of the Cingoli anticline, about 4-5 km away from the mountain front. An important role in the tectonic evolution of the study area is also played by inherited (pre-thrusting) structures. These include both those of the rifted continental margin, of Mesozoic age, and those related to Miocene foreland deformation. The former, well known in the geological literature, are organised in two main fault sets (trending NNE-SSW and WNW-ESE). Synsedimentary Miocene faults, mainly trending NNW-SSE, controlled foredeep turbiditic deposition during early (pre-evaporitic) Messinian times. These faults show very limited or no reversal of slip during contractional deformation. In fact, although mild inversion tectonics has produced some uplift and antiformal folding of hanging wall basin fills, only in one instance (i.e. Avenale Fault) has significant fault reactivation occurred. The onset of contractional deformation within the study area coincides with the end of the deposition of the Gessoso-solfifera Fm. Thrusting appears to have migrated in sequence towards the external zones of our study area up to Early Pliocene times (Globorotalia puncticulata biozone).