Apulian Carbonate Platform Research Articles

Meter-scale cycles as a proxy for the evolution of the Apulian Carbonate Platform during the late Cretaceous (Llogara Pass, Albania)

Sedimentological investigations have revealed ten facies in Upper Cretaceous platform carbonates (1220 m thick) at Llogara Pass in southern Albania that can be grouped into four facies associations. These reflect specific environmental conditions, ranging from intertidal to subtidal. The facies form small-scale patterns attesting to high-frequency/low-amplitude cyclicity characteristic of relative sea-level fluctuations. Meter-scale cycles have been classified into six distinct types and characterized on the basis of diagnostic surfaces, diagenetic features, and reservoir properties. A closer look at diagenetic and petrophysical features revealed a drastic porosity reduction at each cycle top (i.e., cycle boundary). This underlines a strong interconnection of facies types and reservoir properties at the cycle scale, thus impacting the whole carbonate succession. The cycle stacking pattern is a reflection of the sedimentary evolution during the late Cretaceous in this southern part of the Apulian Platform. (1) Meter-scale peritidal cycles suggest that the Cenomanian was characterized by stable shallow-water conditions. (2) Thick stromatolitic-dominated cycles typify Turonian deposits. Although the nature of the deposits indicates inner platform conditions, the long-term hiatus documented from Italy (Turonian bauxites) is not evidenced in Llogara. (3) The thin (a few tens of meters) Coniacian–Santonian interval suggests the onset of a significant tectonic control over the sedimentary dynamics, likely accompanied by morphological changes on the Apulian Platform and an emergence of rudist-dominated cycles. (4) Peritidal-subtidal cycles persist during the Campanian, accompanied by a broad development of rudist organisms that evidence significant and repeated relative sea-level rise. These data allow refinement of the general sedimentological evolution during the late Cretaceous on the Apulian Platform.

Genesis of autochthonous and allochthonous Apulian karst bauxites (Southern Italy): Climate constraints

The Apulian Carbonate Platform (ACP) in southern Italy has experienced several episodes of subaerial exposure, which were in some cases associated with the formation of karst bauxite deposits. The ACP contains both autochthonous canyon-like bauxite and allochthonous Salento-type bauxite, with the latter having been derived from a weathered and eroded pristine bauxite deposit. The remnants of this pristine bauxite are preserved as transported pebbles embedded in a clayey matrix.The autochthonous bauxite and the pebbles of the allochthonous bauxite have the same texture of sub-spheroidal components (ooids) dispersed in a fine-grained matrix. The fractal dimension of ooids from both deposits is very similar and corresponds to the growth of "aggregates" under a diffusion-controlled process.The ooids of the autochthonous bauxite have a different composition to those in the pebbles of the allochthonous bauxite, because they formed under different climatic conditions. During the Turonian, autochthonous bauxite ooids formed in alternating wet tropical conditions (promoting Al-hematite formation) and drier conditions (favouring boehmite stability). In the allochthonous pebbles, ooids formed mainly in a dry climate, promoting the formation of large boehmite cores. The ooids/matrix ratio and the geometrical features of the ooids reflect these climate differences.The differences in composition and age (post-Turonian) of the Salento-type bauxite bedrock suggest that the pristine bauxite that produced the Salento-type pebbles was different in composition to and younger in age than the Canyon-like bauxite. The latter probably formed during a middle Campanian emersion event (evidenced by large karstic cavities), which is correlated with the subaerial exposure of karst recorded on the Adriatic island of Brač.

Deformation and stratigraphic evolution of the Ligurian Accretionary Complex in the southern Apennines (Italy)

This work provides a structural analysis and a stratigraphic revision of the sedimentary successions of the Ligurian Accretionary Complex (LAC) cropping out in the southern Apennines along the boundary between Campania, Lucania and Calabria regions. Two fold and thrust sets characterize the progressive deformation related to the Early Miocene inclusion of these successions in the tectonic accretionary wedge. A third deformation stage, affecting also the Middle-Upper Miocene unconformable wedge-top basin deposits, is associated to the thrust front eastward migration. In this orogenic phase the Apennine thrust sheet pile, formed by LAC and Apennine Platform Units, tectonically covered the successions located in the westernmost sector of the Lagonegro-Molise Basin. Finally a Pliocene-Middle Pleistocene regional fold set deformed the whole orogenic prism as consequence of a thick-skinned tectonics expressed by means of deeply rooted thrusts in the buried Apulian Platform carbonates. Maghrebian Flysch Basin and LAC successions show a similar stratigraphy indicating continuity between paleogeographic basin domains, as well as between the Paleogene-Lower Miocene succession of Sicilide Unit and the corresponding deposits of Lagonegro-Molise Basin as consequence of drowning of the interposed Panormide Platform starting from the uppermost Cretaceous.

Tectonic triggering of slump sheets in the Upper Cretaceous carbonate succession of the Porto Selvaggio area (Salento peninsula, southern Italy): Synsedimentary tectonics in the Apulian Carbonate Platform

Soft-sediment deformation structures crop out in the Upper Cretaceous carbonate succession in Porto Selvaggio cove in the western Salento peninsula, Apulian foreland, southern Italy. The deformed interval is about 13m thick and occurs between shallow-water limestones and dolostones formed in peritidal and shallow subtidal environments. It comprises well-bedded grey mudstones interlayered with dark grey laminated microbioclastic wackestones characterized by couplets of closely spaced dark and bright laminae marked by the parallel orientation of calcareous microbioclasts and thin-shelled bivalves. The low biological diversity, scarcity of burrowing biota, and presence of a well preserved fish fauna provide evidence of anoxic conditions occurring in morphological depressions within the platform, and a stagnant, stratified water body affected by weak bottom currents, indicating the sudden development of a localised and short-lived intraplatform basin. Two soft-sediment deformation horizons (slump sheets) separated by undeformed limestones with similar facies occur in this part of the succession. The lower, thicker slump sheet (1.0–1.3m thick) contains asymmetric and box folds. Well-developed décollement surfaces (locally containing thick brecciated zones) cut the folds, forming small-scale thrust-sheets and indicating mixed plastic to brittle behaviour. The upper, thinner slump sheet (0.25–0.35m thick) contains only asymmetric folds, indicating plastic behaviour only. The differences in deformation style are attributed to differences in facies. Measurements of fold-axis orientations in the slump sheets show that they moved in similar directions, recording the development of a local, gently dipping palaeoslope. Autogenic (internal) trigger mechanisms are ruled out by a detailed consideration of facies. The slump sheets were triggered by allogenic, tectonic effects, either the weakening of sediment by seismic activity or the tectonically induced steepening of slopes, or a combination of both. Tectonically induced steepening is consistent with localised and sudden vertical facies changes related to the creation of an intraplatform basin. The occurrence of slump sheets in carbonate platform successions is unusual since carbonate platforms are normally associated with shelves or low-angle ramps.

Modes and timing of fracture network development in poly-deformed carbonate reservoir analogues, Mt. Chianello, southern Italy

Structural and paleostress analyses carried out on a kilometre-sized outcrop of allochthonous shallow-water carbonate units of the southern Apennines allowed us to unravel a superposed deformation pattern associated with plate convergence. The reconstructed tectonic evolution involves: (i) early extensional faulting and fracturing associated with bending of the foreland lithosphere during forebulge and foredeep stages (including the development of both ‘tangential’ and ‘radial’ normal fault and tensile fractures; Early-Middle Miocene); (ii) large-scale thrusting and folding (Late Miocene); (iii) transcurrent faulting (including two distinct sub-stages characterized by different remote stress fields; Pliocene-Early Pleistocene), and (iv) extensional faulting (late Quaternary). Stage (i) normal faults – generally occurring as conjugate sets – and related fractures and veins are variably deformed and overprinted by later horizontal shortening. Despite having experienced such a long and complex structural history, the studied carbonates are characterized by a ‘background’ fracture network – including two joint/vein sets orthogonal to each other and to bedding – that appears to be associated with the early fault sets that formed during the first (foredeep/forebulge-related) deformation stage. Therefore, away from younger (Late Miocene to Quaternary) fault zones, the permeability structure of the studied carbonates appears to be essentially controlled by the early, inherited fracture network. As a similar fracture network is likely to characterize also the buried Apulian Platform carbonates, representing the reservoir units for major oil fields in southern Italy, our results also bear possible implications for a better understanding of fluid flow in the subsurface and related hydrocarbon production.

Late Dolomitization in Basinal Limestones of the Southern Apennines Fold and Thrust Belt (Italy)

The Triassic pelagic carbonates of the Lagonegro Units from the southern Apennines fold and thrust belt host discordant bodies of dolostone. These rocks show textural features typical of zebra or saddle dolomites. In this contribution, the results of field observations, petrography and geochemical analyzes performed on samples from three different outcrops are presented.Field data indicate that the peculiar zebra-type rock and brecciated fabrics were controlled by regular bedding of the micritic, pelagic limestones. The dolomitization resulted in the replacement of the host limestones and subsequent void-filling precipitation of dolomite in a dilatational stress field.Homogenization temperatures (Th) are in the range 80-120°C, with a clear mode of 95 ÷ 10°C. When corrected for maximum pressure, they indicate an upper limit for dolomite formation around 110-115°C. Melting temperatures of ice (Tmi ) point to salinities in the range 2-6 wt% NaCl eq, with a mean of 4.2%. δ 13 C values overlap those of the Upper Triassic seawater, whereas the δ 18 O values are significantly depleted compared to the coeval seawater. 87 Sr/86 Sr values are higher with respect to Upper Triassic seawater, and partially overlap Middle-Upper Miocene values.The performed analyzes indicate a dolomitization process driven by warm fluids (110-115°C) with a salinity close to that of seawater and O-isotope ratios comprised between seawater and formation waters. It is suggested that the dolomitization was accomplished by formation waters squeezed out or from surrounding lithologies or from the underlying melange units. Integration with available thermal data on the collisional history of the belt suggests that the fluid-flow took place after maximum burial, in the early stages of exhumation, in the assumption of a fluid in thermal equilibrium with the host rocks.According to literature data, the dolomitization event was quite widespread. It can be argued that it was part of a major fluid-flux associated with fold and thrust belt development, which possibly affected the Apulian Platform carbonates located in the foreland. The latter, now buried below the nappe stack, hosts some of the major oil fields of continental Europe.

A new purported ankylosaur trackway in the Lower Cretaceous (lower Aptian) shallow-marine carbonate deposits of Puglia, southern Italy

The Apulian marine carbonate Platform, an unusual environment for terrestrial animals, has revealed a diverse ichnological record, especially for dinosaurs. Members of most higher taxa are present, including sauropods, theropods, ankylosaurs and ornithopods. Recently, a small outcrop of Aptian age referred to the Calcare di Bari near Bisceglie (Bari) has yielded a new quadrupedal trackway that we attribute to Ankylosauria. This new find enhances the record of Cretaceous ankylosaur footprints from the Apulian carbonate Platform, previously known from another site near Bisceglie (early Aptian), from Borgo Celano (late Hauterivian–early Barremian), and from Altamura (late Coniacian–early Santonian).

Le litofacies permiane e triassiche della formazione di M. Facito auctt. nell’area di M. Facito (successione di Lagonegro, Appennino meridionale)

Aim of this paper is to obtain a better definition of the stratigraphic succession of the M. Facito fm. that is the oldest part of the Lagonegro Mesozoic basin in Southern Apennines (Italy). Seismic data show that the Lagonegro succession overthrusted the western part of the Apulian Carbonate Platform and so the M. Facito fm. appears as a broken formation composed by a variety of different lithofacies. They were partially described by CIARAPICA & PASSERI (2000) in the two other typical areas. This paper, therefore, contribuetes to obtain a complete panorama of the lithofacies contained in the M. Facito fm. a) Calcirudites with fusulinids (Upper Permian). They are known only as scattered boulders and pebbles in tectonic melange and debris. These boulders are interpreted as tectonic shavings coming from melanges and reworked in the postorogenic debris flow. They are the only witness of the Permian in Southern Apennines. b) Capelluzzo lithofacies (Spathian-Aegean). It consists of black calcilutites, slates and calcarenites with abundant quartz grains. Sedimentary structures allowed us to recognize a coastal environment with offshore facies (thin-bedded black limestones), transition facies (limestones, slates and thin layers of cross-laminated quartz calcarenites) and shore-face facies (amalgamated beds of quartz calcarenites). c) Pietra Maura lithofacies (Anisian p.p.). It is represented by massive limestone with green algae, encrusting organisms, foraminifera and brachiopods. The main outcrops of Pietra Maura and Le Ripe are interpreted as carbonate build-ups. Sometimes they show evidence of exposure on the top. d) Varesano lithofacies (Anisian p.p.). It consists of marls, shales and sandstones. It partially lies by side and partially on the top of the previous lithofacies. The same species of brachiopods are contained in both the Pietra Maura limestone and in the shales and sandstones of Varesano, documenting their same age. Sandstones include quartz-wackes, quartz-psammites and quartz-arenites. In some outcrops they contain beautiful wavy ripples and burrows, but in other places they show turbidites with thick graded beds, flute casts, clay chips and current ripples. Sandstones with wave ripples overlying marls indicate a regressive trend. Turbidites are likely a witness of the successive deepening. e) Bellagamba lithofacies (Ladinian p.p.). This lithofacies marks the birth of the deep-water Lagonegro basin. It contains red nodular limestone (Rosso Ammonitico Auctt.) with very rare ammonites but rich in conodonts (early Fassanian to late Longobardian p.p.), radiolarian chert and true radiolarites. Calcirudites and megabreccias include elements coming from Ladinian build-ups that are not present in the Mt. Facito area but that are well known in other zones as Tempa di Rocca Rossa (Tempa di Rocca Rossa lithofacies, Ladinian p.p.). f) Petina Chiana lithofacies (late Longobardian to early Julian). This lithofacies is characterized by the presence of red shales and thin-bedded calcilutites with radiolarians and thin-shelled pelecypods (filaments). It contains the Ladinian-Carnian boundary and it marks the transition to the overlying Calcari con Selce fm. (Carnian and Norian).Some lithofacies lacking of clear relationships with the previous ones (Lithofacies Incertae Sedis) are also described in this paper. Among them, the Cognone lithofacies, that was settled down in a coastal environment and could be referred to the Anisian. The last subject is devoted to the description of the melange, well developed in the Mt. Facito area. It is possible to distinguish synsedimentary, synorogenic and postorogenic melange. The first one is represented by the Bellagamba lithofacies (radiolarites with calcirudites) that is the expression of the Middle Triassic rifting of the Ionian Ocean. The second one is related to thrust surfaces and it contains shavings of the oldest parts of the Lagonegro succession (Permian limestone and phyllites pebbles) sometimes mixed with Cretaceous elements of the «flysch galestrino fm.». The third one is very common and it consists of weathering products, loose sediments by mass flow and, sometimes, well cemented fluvial conglomerates. The abundance of melanges in the outcrops of Mt. Facito fm. probably lead to misinterpret it as a unique, huge olistostroma. In our opinion the fragmentary character of this formation is mainly due to tectonics

Tectonic burial and “young” (<10 Ma) exhumation in the southern Apennines fold-and-thrust belt (Italy)

In the southern Apennines fold-and-thrust belt, thermal indicators record exhumation of sedimentary units from depths locally in excess of 5 km. The thrust belt is made of allochthonous sedimentary units that overlie a 6–8-km-thick, carbonate footwall succession. The latter, continuous with the foreland Apulian Platform, is deformed by reverse faults involving the underlying basement. Therefore, a switch from thin-skinned to thick-skinned thrusting occurred as the Apulian Platform carbonates—and the underlying thick continental lithosphere—were deformed during the latest shortening stages. Apatite fission track data, showing cooling ages ranging between 9.2 ± 1.0 and 1.5 ± 0.8 Ma, indicate that exhumation marks these late tectonic stages, probably initiating with the buttressing of the allochthonous wedge against the western margin of the Apulian Platform. Pliocene-Pleistocene foreland advancing of the allochthonous units exceeds the total amount of slip that, based on cross-section balancing and restoration, could be transferred to the base of the allochthon from the underlying thick-skinned structures. This suggests that emplacement of the allochthon above the western portion of the Apulian Platform carbonates was followed by gravitational readjustments within the allochthonous wedge, coeval—and partly associated with—thick-skinned shortening at depth. The related denudation processes are interpreted to have played a primary role in tectonic exhumation.

Chronostratigraphy of Campanian–Maastrichtian platform carbonates and rudist associations of Salento (Apulia, Italy)

Late Cretaceous platform carbonates from the Salento peninsula (south Italy) were studied by strontium-isotope stratigraphy to improve their chronostratigraphy. Forty-three samples from nine localities were collected and the numerical ages were derived from fifteen geochemically well-preserved samples of rudist shells that were analyzed for 87Sr/ 86Sr values. Strontium isotope stratigraphy yielded new ages for the base of the Ciolo Limestone. The oldest successions studied in Salento are 85.9 Ma (+/− 0.6) and assigned to the Melissano Limestone. The youngest Cretaceous limestones observed at the Ciolo Limestone type locality (Ciolo cove) are 66.4 Ma (+/− 1.5), and the base of this formation is older than 72.8 Ma (+/− 0.4). Karstic cavities observed at the Cava Cocumola in the mid-Campanian S. Cesarea Limestone are tentatively interpreted to be linked to an intra-Campanian event which is related to a sea-level lowstand inferred also on the island of Brač (Adriatic coast of Croatia) and in the Boreal realm at 75–77 Ma. A new large recumbent rudist similar to Sabinia and Pseudosabinia is observed in the Ciolo and S. Cesarea Limestone and appears to be characteristic of the Apulian platform carbonates. Rudist associations from the S. Cesarea Limestone and the overlying Ciolo Limestone are remarkably similar, although they range over a time interval of more than 12 Ma.

Thin-skinned versus thick-skinned structural models for Apulian carbonate reservoirs: constraints from the Val d'Agri Fields, S Apennines, Italy

The Apulian Platform Carbonates form the reservoir unit in several major oil fields in the Val d'Agri area of southern Italy. Traps are formed by compressional fold structures developed in the hanging wall of major reverse faults. Published models for these structures emphasize a ‘thin-skinned’ tectonic style with a basal detachment located in Triassic evaporites. However, the generally poor quality of seismic data in the southern Apennines means that subsurface geometries are poorly constrained and seismic-structural interpretation becomes model-driven. The density of data associated with field development in the Val d'Agri area provides an opportunity to constrain structural models at a variety of scales. Good quality seismic data image the front of the Monte Alpi field and show involvement of the Base Apulian seismic reflection in compressional structures. Locally, well-defined fault plane reflectors image the moderate-steeply dipping, convex-up reverse faults that bound the structures. Integration of well, vertical seismic profiles and seismic data confirm the dominance within the reservoir of moderate-high angle reverse and normal faulting. Taken together these elements suggest that a thick-skinned structural model is most appropriate for the Val d'Agri Apulian structures, whilst the geometry of the main bounding faults suggests that they are inverted Permo-Triassic extensional faults.

Thin-skinned vs. thick-skinned tectonics in the Matese Massif, Central–Southern Apennines (Italy)

Combined structural and geophysical investigations were carried out in the Matese Massif at the boundary between the Central and the Southern Apennines. The aim of this research was to define the structural geometry and the kinematics of Neogene deformation in order to validate the applicability of either thin-skinned or thick-skinned compressive styles in the Apennines of Italy. On the basis of two surface N–S cross-sections, integrated with recently acquired magnetotelluric data, the Matese structure appears as a single thrust sheet limited at the bottom by a low-angle thrust fault with sense-of-displacement towards the North. The structure was later deformed by footwall thrusts carrying Molise–Sannio Pelagic Basin Units and Apulian Carbonate Platform Units. The structure of the Matese Massif is composed mainly of Mesozoic carbonates of inner platform to by-pass and slope facies, separated within the thrust sheet by high-angle faults with low reverse horizontal displacement. These faults acted as normal faults in the Mesozoic and Cenozoic and controlled the carbonate facies distribution. During Neogene compression, these structures were tilted and then truncated by the basal short-cut thrust fault that cut from pre-Triassic units to Jurassic dolostone towards the foreland. Finally, Quaternary extensional tectonics dissected the whole structure with fault-related displacement values of up to 1000 m. This resulted in the present-day structural setting of the Matese Massif as a horst bounded to the SW and NE by fault-controlled basins, filled with continental deposits. This revised structural scenario is discussed within the framework of the structural style of external zones of the Apennines.

Tectonic burial and exhumation in a foreland fold and thrust belt: the Monte Alpi case history (Southern Apennines, Italy)

The Monte Alpi area of the Southern Apennines represents the only sector of the thrust belt where the reservoir rocks (i.e. Apulian Platform carbonates) for major hydrocarbon accumulations in southern Italy are interpreted to crop out. Tectonic evolution and exhumation of this area were analysed by integrating stratigraphic and structural data with different organic and inorganic parameters The record the burial and thermal evolution of the sediments (vitrinite reflectance, fluid inclusions, and I/S mixed layers in clayey sediments). Our analyses suggest that the presently exposed Monte Alpi structure suffered a loading of ca. 4000 m, owing to the emplacement of allochthonous units in Early Pliocene times. Available geological data indicate that erosion of the tectonic load occurred since the Late Pliocene, when the area first emerged. This implies an average exhumation rate in excess of 1 mm/year. A model can be constructed which matches the maturity indices and also takes into account intermediate stages of the evolution, resulting from combined structural and fluid inclusion data. By this model, a first stage of exhumation would have taken place at an average rate of about 0.36 mm/year. This was controlled by uplift and erosion associated with both: (i) thrusting at depth within the Apulian carbonates (Late Pliocene), and (ii) strike-slip faulting (Early Pleistocene). A second exhumation stage would have occurred in the last 700 ky at a much faster rate (ca. 4 mm/year) as a result of extensional tectonics. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.

Tectonic burial and exhumation in a foreland fold and thrust belt: the Monte Alpi case history (Southern Apennines, Italy)

The Monte Alpi area of the Southern Apennines represents the only sector of the thrust belt where the reservoir rocks (i.e. Apulian Platform carbonates) for major hydrocarbon accumulations in southern Italy are interpreted to crop out. Tectonic evolution and exhumation of this area were analysed by integrating stratigraphic and structural data with different organic and inorganic parameters which record the burial and thermal evolution of the sediments (vitrinite reflectance, fluid inclusions, and I/S mixed layers in clayey sediments). Our analyses suggest that the presently exposed Monte Alpi structure suffered a loading of ca. 4000 m, owing to the emplacement of allochthonous units in Early Pliocene times. Available geological data indicate that erosion of the tectonic load occurred since the Late Pliocene, when the area first emerged. This implies an average exhumation rate in excess of 1 mm/year. A model can be constructed which matches the maturity indices and also takes into account intermediate stages of the evolution, resulting from combined structural and fluid inclusion data. By this model, a first stage of exhumation would have taken place at an average rate of about 0.36 mm/year. This was controlled by uplift and erosion associated with both: (i) thrusting at depth within the Apulian carbonates (Late Pliocene), and (ii) strike-slip faulting (Early Pleistocene). A second exhumation stage would have occurred in the last 700 ky at a much faster rate (ca. 4 mm/year) as a result of extensional tectonics.

Ferruginous concretions in a Late Cretaceous karst bauxite: composition and conditions of formation

The karst bauxites from the Apulian carbonate platform (southern Italy) have an ooidic texture. The concretions, which are formed at the expense of the kaolinitic matrix, are composed of Al-hematite in the core and of Al-hematite and boehmite in the banded cortex. The Al-hematite in the core has an average formula (Al 0.12Fe 0.88) 2O 3 and the Al is within the range of values observed in hematite formed through in situ epigenetic replacement of kaolinite. The Al substitution in hematite involves a water-unsaturated environment, possibly promoted by fluctuations of the groundwater table followed by intense drainage and evaporation. In the banded cortex, boehmite may form instead of Al-hematite at lower water activity values. Further, the boehmite stability increases for high values of the a Al 3+ / a 3 H + ratio, which is mostly controlled by the pH of the solution. The stability of the Al-hydroxide decreases with increasing pH.

Upper crustal structure in the Potenza area (Southern Apennines, Italy) using Sp converted wave

In this paper we analyse the records of the two Potenza seismic sequences (Southern Apennines, Italy) which occurred in 1990 and 1991, in order to obtain information on the upper crustal structure in this area. The hypocentral depths are mainly concentrated below 10 km which is the supposed upper limit of the crystalline basement. The seismograms recorded at temporary arrays deployed during the two sequences clearly show on the vertical component, an intermediary phase between the P and S waves. For the investigated epicentral distances (less than 30 km) the delay between this secondary phase and the direct S wave arrival is almost constant at each station, suggesting that the observed intermediary phase might be an S to P conversion at a discontinuity shallower than the hypocentral depth. This interpretation has been supported by polarisation analysis and numerical modelling results. Considering the regional geological structure, these latter have also shown that the interface generating strong converted waves could be the top of the Apulian carbonate platform overlaid with recent clay deposits and flysch sediments. 1D inversion of the travel-time data was performed in order to evaluate a local vertical upper crustal profile.

Ce-anomalies in the textural components of Upper Cretaceous karst bauxites from the Apulian carbonate platform (southern Italy)

The chemical and mineralogical composition of Upper Cretaceous Apulian karst bauxites (southern Italy) and their textural components, i.e. ooids and matrix, has been studied. The bulk samples are composed of boehmite, hematite, anatase and kaolinite. The samples collected along a vertical profile show a downward enrichment for the elements Rb, Sr, Ba, Ni and Cr. A similar distribution is observed in deposits bauxitized in situ at the expense of matrix-like material collected in the karst zone. The ooids consist mainly of hematite with minor boehmite and anatase, whereas in the matrix boehmite prevails on hematite, kaolinite and anatase. In the void fillings in the matrix there is a Ca-fluorocarbonate having a Ce/Ce * of 5.8. The ooids, with the exception of Ce, are enriched in REE and show a higher (La/Yb) ch ratio relative to the matrix. The matrix exhibits a large positive Ce-anomaly whereas the ooids have negative Ce-anomaly. The Ce fractionation between the textural components can be explained assuming: (1) Ce oxidation and cerianite precipitation in the uppermost part of the deposits; (2) scavenging of REE from Ce-depleted percolating solutions by the iron oxide, inducing both REE-enrichment and Ce-negative anomalies in ooids; (3) remobilization of cerium as fluoride complex, as a consequence of more acidic conditions in the uppermost part of the deposit, and precipitation of Ce 3+ as fluorocarbonate mineral toward the carbonate bedrock barrier, at alkaline pH. Alternatively, the cerium remobilization, possibly as a carbonate–fluoride complex, could be due to an Eh decrease, favoured by a rise of the groundwater level.

Hydrogeological implications of the resistivity distribution inferred from electrical prospecting data from the Apulian carbonate platform

Electrical and magnetotelluric surveys have been performed on the Apulian carbonate platform to study the deep coastal karst aquifer. The surveys extend to a depth of about 7 km, to give a complete hydrogeological understanding of the area. The problems of interpreting regional geophysical data in highly heterogeneous carbonate rocks are extensively analyzed. This study suggests that the aquifer is generally confined at both the top and the bottom by more compact carbonate rocks and has a maximum depth of about 2 km. Also, seawater invasion is both areally and vertically limited. The possibility that dolomite rocks, present in the 2–5 km depth range, could also hold low-salinity waters is discussed. All the hydrogeological features of the investigated area are found to be mainly dependent on the tectonic evolution of the carbonate platform.

Stratigraphy and tectonics offshore of Puglia (Italy, southern Adriatic Sea)

The structural and stratigraphic framework of Puglia offshore between the Gargano promontory and the town of Brindisi (southern Adriatic Sea) has been analysed based on 1700 km of multichannel seismic profiles and 10 exploratory wells. The area includes two different geodynamic settings: (1) part of the undeformed Apenninic foreland (“Apulian carbonate Platform”), consisting mainly of shallow water Mesozoic carbonates, and (2) part of the southern Adriatic Basin, which represents the foredeep of the Hellenic thrust system. A Mesozoic slope, buried by Tertiary clastics and corresponding to the edge of the Apulian carbonate platform, is observed on seismic data. The present physiography of the escarpment is the result of an erosional retreat mainly developed during the Tertiary and related to the subsidence of the South Adriatic Basin; at the same time carbonate facies belts, as evidenced by well data, seem to suggest that in some sectors of the margin the original Mesozoic physiography has been preserved and fossilized. Three seismostratigraphic units, separated by regional or local unconformities, have been distinguished in the Neogene clastic sequence of the South Adriatic Basin. Significant deformations in the sedimentary cover are represented by various antiforms. One of these antiforms, named the “Gondola” ridge, is an elongated, positive structure deforming the pre-Tertiary basement. The western sector of the Gondola ridge belongs to a major E-W strike-slip lineament extending on land in the Gargano promontory. In the eastern part of the area in question some tectonic features, resembling “pop up”-like and thrust antiforms, are arranged along an arcuate pattern named here “Grifone” trend. The Grifone trend structures indicate a post-Pliocene tectonism probably related to the late stages of the Dinaric-Hellenic orogenesis. The recent westward migration of the Hellenic fold and thrust belt can be demonstrated by the South Adriatic foredeep shift during the last 5–6 million years.