Latium-Abruzzi Carbonate Platform Research Articles

The controlling factors on bioclastic intercalations in the Tortonian hemipelagic marls of Latium-Abruzzi carbonate platform domain: the role of oceanography and climate

The controlling factors on bioclastic intercalations in the Tortonian hemipelagic marls of Latium-Abruzzi carbonate platform domain: the role of oceanography and climate

Fault-Block Platform Evolution between Late Cretaceous and Early Miocene along the Margin of the Latium-Abruzzi Carbonate Platform (Southern Prenestini Mountains, Central Apennines, Italy)

Since the origin of the carbonate platform concept, the reconstruction of the geometry and the evolution of the margin has been an intriguing topic. The Latium-Abruzzi platform is one of the largest shallow water domains of the Central Apennines, however, the reconstruction of the geometry and evolution of its margin has been classically problematic because the latter has been erased by the out-of-sequence Olevano-Antrodoco thrust system. The investigated area is placed in the Prenestini Mountains, the southernmost portion of the Sabina Domain, where a Cretaceous to Neogene carbonate succession, ascribed the Latium-Abruzzi platform margin, crops out. Stratigraphic and facies analyses showed a Late Cretaceous extensional stage that produced two main fault-block platforms, respectively, South Eastern Prenestini and South Western Prenestini platforms, developed westward of the large Latium-Abruzzi Platform domain. In these platforms, during the Paleocene–Eocene interval, pelagite deposition coincides with the main relative sea-level rise. Instead, during the following falling stage, the seafloor, consisting of the Cretaceous carbonate, was in the wave abrasion zone and the pelagic carbonate mud was swept away or trapped in local depressions or fractures (neptunian dykes), whereas the coarse sediment produced by the erosion of indented and fractured substrate formed polygenic conglomerate accumulation on the Cretaceuos carbonate platform substrate. Successively, an isolated homoclinal ramp, the Guadagnolo Fm, Aquitanian to Serravallian in age, developed on the drowned fault-block platforms, suggesting that during Neogene the articulation of the substrate of the two fault-block platforms had to be limited to host the bioclastic sedimentation of the Guadagnolo Fm and to allow the development of a carbonate ramp depositional profile.

Post-rift extensional tectonics at the edge of a carbonate platform: insights from the Middle Jurassic-Early Cretaceous Monte Giano stratigraphic record (central Apennines, Italy)

A new interpretation of the Middle Jurassic-Early Cretaceous paleogeographic evolution of the NW sector of the Latium-Abruzzi carbonate platform facing the Umbria-Marche Basin is proposed, based on Monte Giano area (central Apennines, Italy). During Late Triassic-early Bajocian time, the area was characterized by shallow water sedimentation. Inner and marginal carbonate platform deposits are overlain by pelagic deposits (Posidonia level), early Bajocian p.p. in age. This unconformity testifying the sudden drowning of the Monte Giano area, while shallow water sedimentation persisted in the remaining sectors of the carbonate platform. The Posidonia level is paraconformably overlain by distal slope deposits of the Velino Gorge limestones Formation, Kimmeridgian p.p.-Tithonian p.p. in age. Therefore, a 12Ma gap is recorded as in the Umbria-Marche Basin pelagic carbonate platforms. An extensional Bajocian tectonic phase, possibly related to the Piemont-Ligurian Ocean opening coupled with rheologic differences at the basin/platform boundary, drastically changed the regional paleogeography causing the breakup and the drowning of the NW sector of the Latium-Abruzzi carbonate platform and the creation of a large flat-topped pelagic carbonate platform. The estimate offset of the early Bajocian fault is around 300-350m. The Velino Gorge limestones fm. pass laterally and vertically to the Upper Tithonian platform-margin reef complex of the Ellipsactinia limestones fm.; these units constitute a shallowing and coarsening upward sequence and levelled the paleobathymetric gradient created by the Bajocian extension. The progradation of the Latium-Abruzzi carbonate platform continued during Early Cretaceous time. These results have strong implications on the tectonic and paleogeographic evolution of the major domains of the central Apennines.

To be allochthonous or autochthonous? The late Paleocene–late Eocene slope sedimentary succession of the Latium–Abruzzi carbonate platform (Central Apennines, Italy)

Margins, slopes, and toe-of-slopes represent regions of sediment transfer and bypass from shallow-water settings to the basin. They are zones of sediment flux triggered by different types of physical process including sediment-gravity flows, storm-driven currents, unidirectional currents, and oscillatory flows. As a consequence, they are zones where sediment can be remobilized and strongly reworked from inner environments to offshore settings and deposited as a mixture of autochthonous/allochthonous sediments. In the Monte La Serra and Monte Torretta (Central Apennines) lower-to-upper Eocene reworked sedimentary succession, two main facies associations are differentiated on textural characteristics and tested for robustness by hierarchical cluster analysis: a grain-supported (packstone-to-grainstone) facies FA1 and a mud-supported (mudstone-to-wackestone) facies FA2. The outcrops allow investigation of the transition zone between the margin of the Latium–Abruzzi platform and the adjoining basin and especially the identification of the carbonate factories that supplied the sediment to the slope zone of the Latium–Abruzzi platform. During the Paleogene, this platform was a shaved isolated platform under the action of waves, with sediment deposition during the transgressive and highstand phases of sea level, and erosion of this material during a subsequent lowstand phase. During these phases, storm-driven currents acted on the carbonate platform, remobilizing, resuspending, and reworking sediments. The remobilized material was transferred from the inner platform on to the slope, generating a mixture of detrital shallow- and deep-water biotic assemblages and depositing autochthonous/allochthonous units mainly constituted by alveolinids, large rotaliids, hooked gypsinids, nummulitids, and orthophragmines (discocyclinids and orbitoclypeids) assemblages. This mixture of shallow- and deep-water biotic assemblages demonstrates that a systematic study of the provenance of carbonate-producing biota, even if they are not preserved in their original context, can be useful in palaeoenvironmental reconstruction of the original carbonate factory system.

Unravelling the origin of a Paleogene unconformity in the Latium-Abruzzi carbonate succession: A shaved platform

The Latium-Abruzzi carbonate platform constitutes the sedimentary record from the Triassic to the late Miocene of the southern Tethyan margin outcropping in the Apennines. This sedimentary succession is punctuated by an important hiatus between the end of the Cretaceous and the early Miocene. This Paleogene hiatus has long been interpreted as the result of prolonged subaerial exposure. However, no evidence of such exposure has ever been documented on the Latium-Abruzzi platform. This is contrary to the coeval and adjacent Apulia and Lessini carbonate platforms where a broadly-developed paleokarst system formed between the Eocene and the early Miocene. The assumption that the Miocene marine transgression deeply eroded a karstified Cretaceous substrate on the Latium-Abruzzi platform is not supported because this surface appears in the field as a perfectly flat, bioeroded paraconformable surface. In this work, a marine origin is proposed for this unconformity. From late Paleocene to early Miocene, the Latium-Abruzzi carbonate platform was a shaved isolated platform exposed to wave action in the middle of the proto-Mediterranean area. Bioclastic sediment accumulated during transgressive and sea-level highstand phases, whereas in the following falling and lowstand stages, sediment was eroded as the seafloor came into the zone of wave abrasion. The sediment eroded from the platform was shed into the basin where it produced coarse bioclastic intercalations in the hemipelagites of the Scaglia Formation. At the end of the Oligocene, when the adjacent basin was filled, a small ramp was established in the transitional zone between the platform and the basin. There, cross-bedded carbonates accumulated in middle to outer ramp environments. The inner ramp remained within the zone of wave abrasion such that sediment generated there was washed out into the middle and outer ramp environments. Finally, in the early Burdigalian, the Mediterranean progressively evolved into closed sea during the initial stages of the closure of Indo-Pacific connection. The reduction of the wave-base depth, typical of an enclosed sea, created increased accommodation space allowing sediments to accumulate and form the complete inner to outer ramp facies belts of the Miocene Latium-Abruzzi ramp.

Sedimentology and depositional architecture of tidal compound dunes on a carbonate ramp: The lower Miocene deposits of the central Apennine (Latium, Italy)

The sedimentology and sequence stratigraphy of the central Apennine lower Miocene carbonate deposits (Guadagnolo Formation) are the goal of this paper. The Guadagnolo carbonate ramp deposits consist of a thick succession of three main lithofacies: marls, marly limestones and cross-bedded limestones. The lateral and vertical facies distribution, as well as the biota assemblages, suggests a deposition of these sediments along the middle-outer ramp sector of the Latium-Abruzzi carbonate platform. All the data suggest sedimentation under the influence of tidal currents that were responsible of bedforms generation as simple and compound dunes. These bodies are developed on metric and decametric scale, and are stacked one to other to form complex sedimentary bodies extending both in strike and dip section for several tens to hundred meters. The dune system developed in a semiclosed basin (the Paleoadriatic sea), open in the southern and closed in the northern sector respectively. Within this basin a probably amphidromic system developed. The flow sediment transport was dominantly westward, and was conditioned by the ramp paleotopography. From a sequence stratigraphic point of view several high and low rank depositional sequences that were differentiated basing on their relative physical scale (thickness of each unit) and on the lateral extension of the unconformities and the correlative conformities bounding them were recognized. The hierarchy of recognized sequence-stratigraphic units include, from the smallest to the largest: simple depositional sequences, low-rank composite depositional sequences and high-rank composite depositional sequences. In the Guadagnolo succession four high-rank composite depositional sequences having a duration variable from 0.9 to 1.6 Ma, and named Guadagnolo 1, 2, 3, and 4, were recognized. These high-rank composite sequences are internally constituted by a stacking of simple and low-rank composite depositional sequences, having a duration ranging from 40 ka to 200 ka. All these units constitute part of a higher-rank composite sequence developing between 21 and 14.80 Ma that we name “The Guadagnolo Depositional Sequence”. The wedge-shaped geometry, the thickness variation and the stacking pattern of the Guadagnolo succession are the response to eustasy and tectonic subsidence. The glacial eustasy mostly controlled the formation of the high-frequency depositional sequences, tectonic subsidence, related to the roll-back of the hinge west-directed subduction in turn connected to the advancement of the Apennine thrust modulated the accommodation space.

The Coniacian–Campanian Latium–Abruzzi carbonate platform, an example of a facies mosaic

This paper presents the results of a high-resolution analysis of Upper Cretaceous shallow-water limestones in the northeast sector of the Lepini Mountains (Central Apennines, Italy) that belong to the Latium–Abruzzi platform domain. The studied succession is entirely referred to as the “Accordiella conica & Rotorbinella scarsellai Biozone”. The analyzed Coniacian–Campanian succession is primarily characterized by three lithofacies associations (LF-A, LF-B, LF-C) deposited on an open shelf. The intertidal and shallow-subtidal environments are characterized by mudstone to wackestone and laminated bindstone (LF-C), whereas in the low to moderate energy environments of the inner shelf there developed rudist biostrome (rudist pillarstone) and rudist rudstone to floatstone (LF-A). A lithofacies association dominated by cross-bedded grainstone (LF-B) represents the reworking of bioclastic grains (rudist fragments) derived from the areas of the shelf colonized by rudist biostrome; lime-sand shoals related to storm channels passed into submarine dunes in an open-shelf setting. Correlation of the five investigated stratigraphic sections shows how the recognized LF are laterally associated to form a facies mosaic over a few hundred meters. The stratigraphic architecture shows five intervals (I–V) each of which is dominated by one or two LF. Interval I is intensely dolomitized. The following intervals (II and III) record a gradual increase in hydrodynamic energy as evidenced by the presence of rudist biostromes passing upward into cross-bedded grainstone. An increase in mud-supported textures in the interval IV suggests more restricted conditions, which were terminated by a period of emergence. More open-marine conditions in the final interval (V) are shown by the dominance of LF-A and LF-B.

Mesozoic Syn- and Postrifting Evolution of the Central Apennines, Italy: The Role of Triassic Evaporites

AbstractJurassic–Cretaceous syn- and postrift successions from the central Apennines were backstripped to gain information on the Mesozoic evolution of the passive margin of the Adriatic Plate. Early Jurassic rifting led to the development of a horst-and-graben paleogeography (the Latium-Abruzzi Carbonate Platform and the Sabina-Umbria-Marche Pelagic Basin). Subsidence curves were built for both carbonate platform and pelagic-basin domains from original and literature stratigraphic data. The paleodepositional depths of the deepwater sediments were reconstructed from field geology data, including new paleontological data. It is proposed that after the deposition of lower Hettangian shallow-water carbonates, an abrupt increase in paleowater depth, to 600–1000 m, occurred during the late Hettangian–Sinemurian synrift stage. The postrift stage was characterized by basin filling, with decreasing paleowater depths during the Jurassic, and by a new deepening during the Cretaceous. Our backstripping curves show, ...

Assetto strutturale della catena a pieghe e sovrascorrimenti Umbro-Sabina (Italia Centrale) derivato dal rilevamento dei fogli 366 “Palombara Sabina” e 375 “Tivoli” (Progetto CARG).

Structural Scheme of the Umbria-Sabina fold-and-thrust belt (Central Italy) derived from the geological mapping of 366 Palombara Sabina and 375 Tivoli sheets (CARG Project).The geological mapping of the sheets 366 Palombara Sabina and 375 Tivoli (1: 50.000 scale; CARG Project; in preparation) allowed the revision of the structural setting of the westernmost portion of this part of the Neogene fold-and-thrust belt of the Central Apennines.The area comprises the Cornicolani, Lucretili, eastern Sabini, Tiburtini, Ruffi and Prenestini Mts (Latium region). Most of the area (Cornicolani, Lucretili and Tiburtini Mts) is made of the pre-orogenic deposits (Upper Triassic-Serravallian) referred to the calcareous-marly-siliceous Sabina Succession, that were accumulated in the southern part of the Umbria-Marche-Sabina Pelagic Basin (Sabina Domain), proximal to the Latium-Abruzzi Carbonate Platform. In general, in the eastern areas, more proximal to the platform, coarser lithofacies crop out. Moreover, in the Cornicolani and western Lucretili Mts (Castelvecchio Mt) areally restricted outcrops of condensed pelagic carbonates (Bugarone Group and calcari dolomitici di S. Angelo Romano) document the occurrence of Jurassic intrabasinal structural highs evolved into Pelagic Carbonate Platforms. These structural highs were generated after the Early Jurassic rifting, that broke-up the pre-existing carbonate platform (Calcare Massiccio).In the mapped area, the Latium - Abruzzi Platform is represented in the hangingwall of the Olevano-Antrodoco line only in the southern Prenestini Mts (Rocca di Cave), by upper Cretaceous shelf carbonates. Whereas in the footwall of the Olevano-Antrodoco line it crops out along the Aniene River valley. Both Sabina and Latium - Abruzzi successions are overlain by upper Tortonian - lower Messinian marls and siliciclastic syn-orogenic deposits, best observed in the easternmost areas and inbetween the Ruffi and Prenestini Mts.In their turn, the syn-orogenic deposits are unconformably overlain by post-orogenic Plio-Pleistocene marine clastic deposits and Quaternary volcanic and alluvial sediments. From a structural point of view, the Sabina Domain is arranged into several thrust sheets verging toward the east, developed in middle-late Miocene-early Pliocene times. The early Pliocene Olevano-Antrodoco out-of-sequence thrust marks the eastern tectonic boundary of this structural domain where the pelagic and slope sediments overthrust the Latium - Abruzzi Carbonate Platform and its associated syn-orogenic deposits. In late Miocene-early Pliocene extensional tectonics down-threw the western border of this imbricated structure enhancing the marine ingression along the peri-Tyrrhenian margin. The western border of the region was also reactivated by N-S right-lateral strike-slip fault dissecting the earlier structures in Pleistocene times.From top of the orogenic edifice three main tectonic units have been identified:- Unit 1 (Morra Mt) made up of Upper Triassic to Lower Jurassic dolomite limestones (Dolomia Principale) and Calcare Massiccio, overthrust onto unit 2.- Unit 2 (comprising Cornicolani Mts, western Lucretili Mts) made up of Dolomia Principale, Calcare Massiccio, Corniola detritica and, in the Cornicolani and western Lucretili Mts, Bugarone Group. Long wavelength upright folds mainly characterize this unit and faults with high angle cuts-offs prevail, and Jurassic structural highs occur (Cornicolani Mts, Castelvecchio Mt).- Unit 3 (comprising Elci Mt, eastern Lucretili Mts and Tiburtini Mts) made up of most of the Sabina basin stratigraphic succession - from Corniola detritica Fm. to the Guadagnolo Member (marly lithofacies); the unit is characterized by NW to NE verging overturned to recumbent folds.- Unit 4 (comprising Prenestini Mts, Ruffi Mts and eastern Sabini Mts) made up of the upper portion of the basin succession between the Marne a Fucoidi and Upper Miocene siliciclastics and the Rocca di Cave carbonate platform succession.This unit is made up by two sub-units, based on the deformation-style and stratigraphy: the sub-unit 4A (Granaro Mt, Colle Serviano and Arzillo Mt in the western Prenestini Mts), is mainly characterized by east-verging packed asymmetrical folds with sub-vertical axial-planes, and N-S striking dextral-transpressive faults. The sub-unit 4B (Castel Madama area, eastern and central Prenestini Mts, Ruffi Mts and eastern Sabini Mts) is characterized by a wide symmetrical anticline in the western portion, and by folds with very steep axial planes, and N-S to NNW-striking dextral transpressional faults.The units are separated by low-angle thrusts or by high-angle transpressive faults: the stratigraphic successions characterizing each unit rejuvenate eastward. The innermost unit 1 and unit 2, where massive or poorly stratified deposits are exposed, are mainly deformed by high angle faults. Whereas the more external unit 3 and unit 4 are composed by alternating carbonate, marls and siliciclastics, and are mostly characterized by east-verging slightly to strongly asymmetrical and overturned folds.A new geometric and kinematic scenario for the Neogene evolution of the units preserved in the hangingwall of the Olevano-Antrodoco thrust is here outlined.The revision of the stratigraphy and structural data put in evidence the presence of paleo-structures of the Tethyan passive margin not evidenced in the past cartography, their influence on Neogene compressive structures and the coexistence of non-coaxial structural trends in areas of limited extension.

Contribution of calcareous nannoplankton to carbonate deposition: a new approach applied to the Lower Jurassic of central Italy

The Upper Pliensbachian–Lower Toarcian Somma section (Central Italy), which displays alternation of limestone–marl lithotypes, was investigated for its calcareous nannofossil and CaCO 3 contents. In order to evaluate the contribution of calcareous phytoplankton to the carbonate fraction of rocks a new method was applied combining a recently developed technique for nannofossil absolute quantification and measurements of nannofossil size. Our study suggests that nannofossils did not produce the bulk of carbonate mud in the studied section, although they contribute to different extents to the pelagic carbonate fraction. The contribution of both coccoliths and (mainly) the Incertae sedis Schizosphaerella to the carbonate fraction was important only in periods of reduced accumulation rates and/or during clay deposition. The highest estimated carbonate production by nannofossils in the studied section is around 83% of the total carbonate content, but in a sample containing only 12.8 wt% CaCO 3. The observed limestone–marl alternations therefore result from cyclical export of carbonate mud from the shallow Latium–Abruzzi carbonate platform to the Umbria–Marche Basin and, only subordinately, from changes in nannoplankton productivity.

Fluvial dynamics in the Castel di Sangro plain: morphological changes and human impact from 1875 to 1992

In recent years, morphology and hydrogeology of the Castel di Sangro plain have undergone significant man-made changes. The plain is located in a very complex geological area where the Latium-Abruzzi carbonate platform, the Morrone-Rotella-Pizzone carbonate platform and the Molise nappe meet. Hydrology, hydrogeology, morphology and neotectonics of the area are conditioned by interlocking and overlapping of such palaeogeographic units. Some of them can be clearly recognised in the upper and middle Sangro area. After outlining the geological, structural and geomorphological features of the area, the authors discuss the morphological changes which occurred in the Sangro River pattern and its alluvial plain from 1875 to 1992 as a result of construction of major hydraulic structures (dams, river bed cementation, urbanisation of flood plain and spring areas, wells). Elements inferred from comparison of maps and aerial photographs were also considered. The study provides a concise description of objective observations on both natural and man-induced fluvial processes and groundwater flows.

Thrusting and strike-slip tectonics in the Alto Molise region (Italy): implications for the Neogene-Quaternary evolution of the Central Apennine orogenic system

The Alto Molise area belongs to the Apennine orogenic belt, which has been developing since the Late Cretaceous as a result of the Europe–Africa collision. This area is characterized by the complex superposition of different palaeogeographic domains that developed during the Mesozoic along the passive southern margin of Tethys Ocean. These domains have been subdivided into four main structural units; from shallowest to deepest they are: the Sannio pelagic basin, the Latium-Abruzzi carbonate platform, the Molise pelagic basin and the Apulia carbonate platform Units. Until the present study, the tectonic relationship among these units was thought to have been mainly determined by Early Messinian to Late Pliocene thrusting. This paper reports the results of a new geometric and kinematic analysis of the Alto Molise area. This new interpretation of the Alto Molise structural style indicates that strike-slip tectonics played a primary role during post-Pliocene times, greatly modifying the previous Alto Molise thrust structures. Two main tectonic events are recorded, consisting of the Pliocene thrusting of the Molise domain onto the Apulia platform followed by the post-Pliocene disruption and rotation of the pre-existing compressional structures by N–S-oriented, high-angle, right-lateral strike-slip faults. These faults are manifest in the Apulia platform as narrow shear zones, but propagate towards the surface into wider belts of strike-slip and oblique-slip deformation. We have compared our results with published structural, palaeomagnetic and anisotropy of magnetic susceptibility (AMS) data from the Central Apennines. This comparison suggests that the superposition of the younger strike-slip tectonic deformation on the older fold and thrust structures in the Alto Molise area is consistent with block-rotation of a segmented orogen, applied to the whole Apennine system.

Optical parameters of maturity of organic matter dispersed in sediments: first results from the Central Apennines (Italy)

ABSTRACTLevels of organic maturity of Mesozoic and Tertiary sequences outcropping in the Central Apennines have been established, using vitrinite reflectance techniques, the Thermal Alteration Index and fluorescence colours of organic matter dispersed in sediments. These results provide new constraints throughout the Meso‐Cenozoic evolution of this crustal sector. In exploration geology, vitrinite reflectance provides data on hydrocarbon maturation by constraining organic matter maturity. In sedimentary basin modelling, it is adopted to define the palaeothermal regime. Vitrinite reflectance (Ro) also provides information on the burial history of sedimentary basins and may be employed to estimate tectonic uplift and erosion rates. Thermal Alteration Index (TAI) and fluorescence colour values can be correlated with Ro and may be used to estimate the degree of maturation when vitrinite is absent.Samples derived from the Sabini and Tiburtini Mts, in slope facies between the Latium–Abruzzi carbonate Platform and the Umbria–Marche pelagic Basin; from the Simbruini and Ernici Mts, in carbonate Platform facies, and from upper Miocene turbiditic deposits outcropping between the Olevano–Antrodoco Une, towards the West, and the Marsica slope facies, towards the East. Both the pre‐terrigenous Meso‐Cenozoic sequences show a low grade of organic maturity: the Sabini and Tiburtini Mts show Ro values that are less than 0.4%, and the Simbruini–Ernici Range show Ro values that range between 0.5% and 0.65%. Field analysis indicates that the cause of these low maturity levels is that thick sequences of turbidites were never deposited during the Neogene evolution of the Apennine thrust belt. Moreover, Upper Miocene turbiditic deposits also show low maturity levels, with Ro values that are less than 0.5%, indicating that these deposits were never overthrusted by huge volumes of rocks, during the chain building. The slight increase in the maturity level recorded in the Marsica area may be related to local heating along shear zones in areas of strike‐slip tectonics.

Eocene and early oligocene micropaleontology and paleoenvironments in SE Umbria, Italy

A detailed study, based on calcareous nannofossils and planktonic and benthic Foraminifera, has been carried out on five sections in the “Scaglia” Group of the Umbrian region (Visso and Cascia areas, Central Italy). These sections are characterized by continuous pelagic sedimentation and are constituted mainly of marls, marly limestones and limestones of Early Eocene to Early Oligocene age. Calcareous turbidites, with shallow-water skeletal debris, discharged from the Latium-Abruzzi carbonate platform, are interbedded within the pelagic sequences. The biostratigraphic study, based on calcareous nannofossils and planktonic Foraminifera, confirmed the continuous succession of standard events and revealed some new ones. These results allow us to refine the biostratigraphic resolution, with a very good correlation between calcareous nannofossil and planktonic foraminiferal zonations. The major features and events recognized are: • The Early-Middle Eocene boundary (Zones P9–P10) is characterized by the first occurrence (FO) of hantkeninids, by abundant thick-walled Globigerinatheka (G. senni) and by spinose acarininids. A decrease has been noted in planoconvex morozovellids and an increase of low-spired subbotinids. • The benthic assemblage shows a great variability, with an increase in the Zone P11 of the large Heterolepa and Cibicidoides. This is an event of worldwide significance. • In the calcareous nannofossils, the FO of Nannotetrina sp. was used to define the lower boundary of Zone CP13 instead of N. fulgens, because poor preservation prevented identification at the specific level. • The FO of Reticulofenestra umbilica, marking the lower boundary of Zone CP14, occurs in the upper part of Zone P11. • The Zone P13 was recognized indirectly because of the absence of the index species Orbulinoides beckmanni. The base of the zone is close to the FO of Turborotalia cerroazulensis, and is defined by an increase of Catapsydrax sp. and by the last occurrence (LO) of Acarinina bullbrooki. The top of the zone is defined by an increase of the high-spired subbotinids of the S. corpulenta group and the disappearance of Morozovella spinulosa • The Middle/Late Eocene boundary (Zones P14/P15) is characterized by the extinction of the spinose acarininids and of the smooth-walled Planorotalites. From Zone P13 to Zone P15 there is a replacement in the benthic assemblages. In fact, Pleurostomella, Heterolepa and Anomalinoides capitata characterize these zones, bolivinids become abundant and uvigerinids appear around the P14/P15 boundary. • The Late Eocene is characterized by an increase of subbotinids with abortive chambers and of the Turborotalia cerroazulensis lineage. Hantkeninids and cribohantkeninids are rare, particularly C. inflata. The FO of Istmolithus recurvus has been noted at the base of Zone P16. Within this zone, Globigerinatheka index and Turborotalia cunialensis coexist. The LO of G. index is associated with a strong decrease of representatives of the genus Globigerinatheka. At the same level of the LO of G. index, the coeval extinctions of Discoaster barbadiensis and Discoaster saipanensis are noted. Just above this level, within Zone P17, the LO of T. cerroazulensis lineage ( T. cocoaensis and T. cunialensis) has been recognized. The Eocene/Oligocene boundary is defined by planktonic Foraminifera at the extinction level of hantkeninids and cribrohantkeninids, shortly following that of the T. cerroazulensis group.