Apulian Carbonate Platform Research Articles

Structural architecture and maturity of Val d’Agri faults, Italy: Inferences from natural and induced seismicity

The Val d’Agri Basin is a Quaternary sedimentary basin topping multiple tectonic units of the southern Apennines fold-and-thrust belt and a giant oilfield within deeper Apulian Platform carbonates. This basin is bounded by the seismically active East Agri (EAFS) and Monti della Maddalena (MMFS) extensional fault systems. The reservoir rocks are sealed and separated from shallower thrust sheets by a clay-rich and overpressured mélange. The role of this mélange during fault evolution at shallow crustal levels is widely debated and perhaps underestimated. Here, through multi-scale structural analyses and U–Pb dating of syn-tectonic calcite mineralizations, we gain new insights into the Val d’Agri fault system architecture, their structural maturity, and their relations with both natural and induced seismicity. Consistent with present-day NE-SW crustal stretching, the macro-scale structural architecture of both EAFS and MMFS is controlled by NW-SE and NE-SW fault sets, which displaced and in part re-sheared inherited pre- and syn-orogenic structures. The lack of evident clustering of meso-scale faults and the radial pattern of related slickenlines suggest that polygonal-like faulting occurred, particularly along the EAFS, due to lateral spreading of the Irpinia mélange in the subsurface. Structural data show that the MMFS is characterized by a higher structural maturity (slip longevity), with calcite U–Pb ages indicating the onset of long-lasting extensional tectonics in Early-Middle Miocene time. The original results are discussed in terms of seismotectonic setting of the study area, emphasizing the role played by both the thickness and spatial distribution of plastic mélange in modulating fluid pressure and seismic faulting.

Deriving Vp velocity and density properties of complex litho-structural units from the analysis of geophysical log data: A study from the Southern Apennines of Italy

This study is aimed to define a velocity and density database for the main litho-structural units of the Val d’Agri area of the Southern Apennines (Italy). Here we analyze fifteen digital borehole data comprising sonic log, check shot and density log data with dedicated graphic and statistical tools. We compare velocities acquired with two techniques: check-shots and sonic logging, discussing factors influencing them and their variations with a depth trend. In general, we observe that the comparison between the check shots and the sonic logs velocities gives consistent results. The detailed analysis of well logs and velocity distribution histograms, allow us to distinguish the following eight litho-structural units and their representative velocities and densities: Liguride tertiary flysches; Apennine Carbonate Platform, Lagonegro - Clastics, Lagonegro -Carbonates; Irpinia 1; Irpinia 2 and 3; Volturino foredeep turbidites; Apulian Carbonate Platform. The density values were calculated through the velocity density relationship using the Gardner equation, and subsequently compared with the measured density values. The comparison shows good correlations with the adopted Gardner coefficient of a = 0.30 and an exponent m = 0.25 for carbonatic succession, while a Gardner coefficient of a = 0.25 and an exponent m = 0.28 for clastic lithologies.The obtained results represent a key input for the future velocity and gravity modellings and for the time to-depth conversion of seismic reflection profiles, describing the vertical and lateral lithological heterogeneities between carbonate platforms, deep-sea basinal units and clastic/turbidite successions in the complex tectonic settings of the Southern Apennines.The approach applied in this work, based on a shared analytical and graphical analysis of borehole data, can be readily extended to other case studies worldwide, being the analyzed formations lithologically comparable to many other fold-and-thrust belt rocks.

From outcrop to subsurface model—Large-scale fractured zones in Apulian platform carbonates (Maiella Mountains, Central Apennines, Italy)

From outcrop to subsurface model—Large-scale fractured zones in Apulian platform carbonates (Maiella Mountains, Central Apennines, Italy)

Regional Seismic Characterization of Shallow Subsoil of Northern Apulia (Southern Italy)

A first-order seismic characterization of Northern Apulia (Southern Italy) has been provided by considering geological information and outcomes of a low-cost geophysical survey. In particular, 403 single-station ambient vibration measurements (HVSR techniques) distributed within the main settlements of the area have been considered to extract representative patterns deduced by Principal Component Analysis. The joint interpretation of these pieces of information allows the identification of three main domains (Gargano Promontory, Bradanic Through and Southern Apennines Fold and Thrust Belt), each characterized by specific seismic resonance phenomena. In particular, the Bradanic Through is homogeneously characterized by low frequency (<1 Hz) resonance effects associated with relatively deep (>100 m) seismic impedance, which is contrasting corresponding to the buried Apulian carbonate platform and/or sandy horizons located within the Plio-Pleistocene deposits. In the remaining ones, relatively high frequency (>1 Hz) resonance phenomena are ubiquitous due to the presence of shallower impedance contrasts (<100 m), which do not always correspond to the top of the geological bedrock. These general indications may be useful for a preliminary regional characterization of seismic response in the study area, which can be helpful for an effective planning of more detailed studies targeted to engineering purposes.

The submarine dune field of the Bolognano Fm: depositional processes and the carbonate reservoir potential (Chattian to Burdigalian, Majella Carbonate Platform)

This two-days field trip is focused on the Bolognano Formation, the homoclinal carbonate ramp developed on the Majella Mountain (Central Apennines) from the late Rupelian to the Messinian. The northern sectors of the Majella Mountain show excellent and continuous exposures of this carbonate ramp. In the late Oligocene- early Miocene, the paleoceanography of the Mediterranean was controlled by different seaways, one of the largest being the proto-Adriatic basin, bounded by the Apulian carbonate platform and by the Dinaride coast. In this context, a strong northward current led to the development of submarine dunes during the Chattian and the Burdigalian. In this fieldtrip, we discuss the relationships among sedimentary structures and depositional processes, stratigraphic architecture and syn/post-depositional tectonics. Furthermore, the lower Miocene cross-bedded calcarenites of the Bolognano Fm identify an important reservoir rock. In the last two stops, the bitumen shows are analysed and the possible controlling factors of migration and trapping are discussed. The comparison between bitumen-filled fractured and unfractured rocks allows detecting the controlling factors on the migration of the hydrocarbons and its relationship with tectonics. The high primary porosity and the lateral continuity of the calcarenites are identified as the main controlling factor on the hydrocarbon migration.

On the architecture of intra-formational Mass-Transport Deposits: Insights from the carbonate slopes of Great Bahama Bank and the Apulian Carbonate Platform

Large sub-tropical carbonate platforms shed huge volumes of sediment onto their adjacent slopes. Resulting carbonate successions are comprised of gravity-flow beds (turbidites, debrites), which are occasionally reworked into mass-transport deposits (MTDs) by the failure of inconsistently lithified portions of slope strata. Despite their significance in the depositional record, the internal architecture of MTDs along relatively tectonically stable and sediment-producing carbonate platforms is poorly understood in comparison with counterparts in active compressional tectonic settings. This study compares carbonate-slope-derived MTDs imaged in seismic reflection data with those observed in outcrop. The internal architecture of MTDs from two case studies is presented: the seismically-imaged MTDs in Miocene-Recent carbonate-slope deposits from the Bahamas, and MTDs off the Cretaceous Apulian carbonate margin exposed in outcrops of the Ionian Basin (Albania). Understanding the large-scale (kilometers to tens of kilometers) internal architecture of MTDs in seismic is crucial for identification of these structures in outcrop. In turn, only outcrop studies allow the detailed analysis of the reworking style within these massive sediment bodies at a smaller scale (meters to kilometers). The internal architecture of the studied carbonate MTDs testifies to the existence of an along-slope continuum of deformation structures, characterized by vertical partitioning into distinct mass flows during single mass-transport events. Mass-wasting processes are inferred from strain-partitioning structures, recording along-slope and slope-parallel architectural heterogeneities. Three deformation domains are recognized: extensional headwall domain, translational body domain, and contractional toe domain. Confined MTDs are limited by steep and deep lateral margins and frontal ramps that mark the boundaries between failed deposits and undisturbed strata. Vertical strain-partitioning is pronounced in the toe domain. Upward intensification of deformation within MTDs is common and corresponds to a top-down reorganization of failed strata during downslope transport. Intra-formational MTDs along carbonate slopes that are lacking exotics, such as the ones studied here, differ from extra-formational MTDs occurring in compressional tectonic settings that form sedimentary mélanges. Ductile-layer deformation structures are predominant in carbonate MTDs as opposed to block-in-matrix fabrics in sedimentary mélanges. The development of shear surfaces, rather than ductile shear zones, in the body and toe domains presents predictive (in modern environments) and diagnostic criteria (in fossil examples) of mass-wasting events along carbonate slopes.

Latest fold and thrust tectonics conceals extensional structures inherited from Cretaceous syn-sedimentary deformation: insights for exploration in fold-and-thrust belts from the Maiella Mountain

Abstract The superposition of structures produced by different tectonic phases is common in sedimentary basins. Yet the earlier structures often remain overlooked with potentially negative exploration consequences. In the Maiella anticline, Pliocene compression has folded carbonate sequences containing Cretaceous extensional structures. The geometry and evolution of the Apulian carbonate platform margin outcropping on the Maiella Mountain are described by two opposing groups of models. One proposes a structurally controlled platform margins cut by syn-sedimentary Cretaceous faults; the other assumes a passive Cretaceous palaeo-escarpments progressively filled by Cretaceous to Tertiary sediments later deformed by the Pliocene compression. Assuming models in line with either one of these two groups has significant implications for exploration plays on both platforms and adjacent basins of analogous subsurface systems. These include: hypothesized margin geometries; sediment transport mechanisms (directions and distribution); size of sequences; type and size of traps and associated exploration targets, risks and uncertainties. We demonstrate that during the Late Cretaceous the platform margin was cut by normal faults which controlled the palaeogeography of the platform and the sediment input into the adjacent basin in which thick, resedimented, carbonate megabreccia and turbidites were deposited. These carbonates represent exploration targets in similar settings worldwide.

Nummulitids, Lepidocyclinids and strontium isotope stratigraphy of the Porto Badisco Calcarenite (Salento Peninsula, southern Italy). Implications for the biostratigraphy and paleobiogeography of Oligocene larger benthic foraminifera

The Oligocene Porto Badisco Calcarenite (Apulian Carbonate Platform, southern Italy) contains very rich and diverse assemblages of larger benthic foraminifera. In this paper we provide the first comprehensive taxonomic study of Nummulitids and Lepidocyclinids, based on a biometric approach to species identification. The largerforaminiferal assemblage is dominated by Eulepidina, Heterostegina and Spiroclypeus. Nummulites, Operculina and Nephrolepidina make a subordinate but significant contribution. The concurrent range of the larger foraminiferal species present in the Porto Badisco Calcarenite, and in particular the presence of Spiroclypeus margaritatus and of Miogypsinoides complanatus-formosensis, indicates the late Oligocene Shallow Benthic Zone (SBZ) 23. The taxonomic composition of the larger foraminiferal assemblage of the Apulian Carbonate Platform is very similar to coeval assemblages of other localities of the western Tethyan realm (southern France, southern Spain, Malta, Greece), while some typical components of the SBZ 23 assemblages, like Heterostegina assilinoides and Eulepidina dilatata, are missing in more eastern areas (Turkey, India). Strontium isotope stratigraphy gives an age of 23.6 ± 0.5 Ma for the lower part of the Porto Badisco Calcarenite, constraining the chronostratigraphic calibration of the SBZ 23 within the latest Chattian. This calibration further supports the correlation between the SBZ 23 of the European Basins biozonal scheme with the Te 4 stage of the East Indian Letter Classification.

New Findings On an Orbitolinid Foraminifer Coskinolinella Bariensis (luperto-sinni & Reina, 1992) from the Albian Shallow-water Carbonate Sequence of the Bey Dağlari (s Turkey)

AbstractThe orbitolinid foraminifer Heterocoskinolina bariensis Luperto-Sinni & Reina, 1992, which was first described from the Cenomanian (lower?) of the Apulian Carbonate Platform (southern Italy), has also been found in a Cretaceous shallow-water carbonate sequence of the Bey Dağları Carbonate Platform (Western Taurides, southern Turkey). The morphological analysis, based on numerous successive acetate-peels, revealed annular chambers subdivided into wedge-like chamberlets ( = cupulae) by apparent “radial partitions” produced by the strong infolding of the chamber floor; these are characteristic of the genus Coskinolinella Delmas & Deloffre, 1961. Specimens were compared with descriptions and images of closely related taxa. The stratigraphic position of C. bariensis was determined as upper Albian, based on its occurrence 50 m below the lower–middle Cenomanian Sellialveolina gr. viallii Zone and the presence of Protochrysalidina elongata. Because of its restricted stratigraphic range, this species may have age-diagnostic value for Cretaceous biostratigraphy in restricted platform facies. Other benthic foraminifera, some poorly known, are also documented and illustrated from this same shallow-water carbonate sequence.

The dismantling of the Apulian carbonate platform during the late Campanian – early Maastrichtian in Albania

The Apulian carbonate margin is widely preserved across the Adriatic domain and has been extensively studied in the south of Italy. In Albania, Oligocene–Pliocene fold-and-thrust tectonics led to widespread exposure of the Apulian Platform and associated Ionian Basin carbonates. However, the portion linking the platform to the basin is missing, preventing a direct reconstruction of the platform margin. Syn-sedimentary folding and faulting are recognized in the uppermost part of both the platform and basinal/slope series. Mass transport deposits (MTDs) occur within the platform succession incorporated into well-bedded intertidal (stromatolites) to shallow-subtidal (rudist packstones) sedimentary sequences. They display significant lateral variability which is accompanied by both rigid and soft deformation structures. Spectacular slumps made up of sediment density flow deposits are recognized in the adjacent Ionian Basin. The lateral extent of basal shear surfaces, syn-sedimentary faults and folds evidenced in the Ionian Basin points toward multiple regional tectonic triggering events affecting the Apulian Platform margin at that time. Bio- and chrono-stratigraphic analyses suggest that the triggers occurred during the late Campanian – early Maastrichtian. Beyond the obvious interest from a stratigraphic point of view, the study of these events recording the dismantling of the Apulian carbonate platform allows for a better understanding of the triggering mechanisms and the sedimentary characteristics of MTDs and slumps at a basinal scale.

REEs and U distribution in P-rich nodules from Gelasian Apulian Tethyan carbonate: A genetic record

In the Tethyan realm the carbonate-dominated Meso-Cenozoic South Tethyan Phosphogenic Province is of considerable economic importance since it represents the greatest accumulation of sedimentary phosphorites. In southern Italy, in the Salentine peninsula (the southern part of the Apulian Carbonate Platform, ACP), is well documented the occurrence of Cenozoic P-rich levels consisting of nodules and pebbles and showing a large P2O5 fluctuation (4.07–22.07 wt%), due to variable calcite abundance. The mainly observed P-bearing minerals are hydroxyapatite and carbonate fluorapatite and U, together with Sr and Pb, preferentially acts as Ca substitutes in both lattices. Minor authigenic monazite (LREE-bearing phosphate) and xenotime (HREE+Y-bearing phosphate), likely formed during sediment burial compaction and diagenesis. The total REEs' abundances and the shape of the shale-normalized REE-patterns in the P-rich nodules are in the range of those typically observed in Paleocene-Eocene through Pleistocene-Recent P-rich sediments, supporting the idea of a broadly consistent ocean chemistry in this span of geological time. The (La/Yb)N proxy is within the modern seawater range, signifying early diagenetic adsorption played only a minor role in affecting the REEs' distribution. The Ce and Pr anomalies suggest some P-rich nodules experienced very localized hypoxic to anoxic conditions promoting Ce/Ce* spurious results in a generally oxic to hypoxic environment causing real negative Ce anomaly. This scenario is reinforced by the lack of the coupled uranium-vanadium enrichment typically observed in an anoxic environment. Since the Pliocene the eastern Mediterranean was variously affected by oxygenation and productivity and it is likely the ACP phosphate-rich sediments formed under low sedimentation rates and authigenesis in a bottom current-dominated regime, as also indicated by the glauconite occurrence. Transgressions and sea levels rising following major glaciations may have favored the deposition of phosphate sediments by creating new restricted basin configurations and increased nutrient input promoted by upwelling processes.

Internal architecture of mass‐transport deposits in basinal carbonates: A case study from southern Italy

AbstractSubmarine mass‐transport deposits represent important stratigraphic heterogeneities within slope and basinal sedimentary successions. A poor understanding of how their distribution and internal architecture affect the fluid flow migration pathway may lead to unexpected compartmentalization issues in reservoir analysis. Studies of modern carbonate mass‐transport deposits mainly focus on large seismic‐scale slope failures; however, the near‐platform basinal depositional environment often hosts mass‐transport deposits of various dimensions. The small‐scale and meso‐scale (metres to several tens of metres) carbonate mass‐transport deposits play a considerable role in distribution of sediment and therefore have an impact on the heterogeneity of the succession. In order to further constrain the geometry and internal architecture of mass‐transport deposits developed in near‐slope basinal carbonates, a structural and sedimentological analysis of sub‐seismic‐scale mass‐transport deposits has been undertaken on the eastern margin of the Apulian carbonate platform in the Gargano Promontory, south‐east Italy. These mass‐transport deposits, that locally comprise a large proportion (50 to 60%) of the base of slope to basinal sediments of the Cretaceous Maiolica Formation, typically display a vertically bipartite character, including debrites and slump deposits of varying volume ratios. A range of brittle and ductile deformation styles developed within distinct bed packages, together with the presence of both chert clasts, folded chert layers and spherical chert nodules, suggest that sediments were at different stages of lithification prior to downslope movement associated with mass‐transport deposits. This study helps elucidate the emplacement processes, frequency and character of subseismic‐scale mass‐transport deposits within the basinal carbonate environment, and thereby reduces the uncertainties in the characterization of subsurface carbonate geofluid reservoirs.

Cenozoic tectonic evolution of the northern Apulian Carbonate platform (southern Italy)

A 3D geological modeling of a large portion of the Apulian Platform buried underneath the Bradano Trough, southern Italy, is carried out by integrating 2D seismic reflection profiles, well log data, and published top Apula isobaths. The results of this work highlight the presence of five sets of high-angle, km-long faults, which displace the topmost units of the Apulian Platform. Both timing and kinematics of faulting are investigated by considering age, distribution, and thickness of the Cenozoic sedimentary terranes topping the Mesozoic Apulian carbonates.The study area is characterized by a major fault scarp made up of NW-SE and NNW-SSE fault segments. This structural feature shows a Messinian-Early Pliocene transtensional kinematics, which might have occurred on pre-existing structural heterogeneities. On the contrary, on the basis of their abutting and crosscutting relationships with respect to the aforementioned fault zone, a Pliocene-Quaternary age is inferred for the N-S and NE-SW trending extensional faults, and an Early Pliocene age for the extensional NNE-SSW trending faults. These results are discussed in light of the complex tectonic evolution of the Central Mediterranean area, and may contribute to better assess the structural evolution of the fault network that dissects the northernmost portion of the Apulian Plate, at the boundary with the Adria Plate.

New insights on the structural setting of the Monte Alpi area, Basilicata, Italy

The Monte Alpi is a key area to decipher the structural setting of the southern Apennines fold-and-thrust belt. There, high-angle faults juxtapose Mesozoic carbonates of the inner Apulian Platform, and their terrigenous Messinian sedimentary cover, against the allochthon terranes. In the recent past, two main tectonic models related to the evolution of the Monte Alpi area ascribed the significant exhumation of the Apulian carbonates to two different mechanisms. The first one, highlighted the role of high-angle faults, which affect and cross-cut both carbonates and allochthon terranes. The second model, inferred the significant exhumation of the Apulian Platform carbonates as due to low-angle extensional faulting. In light of the aforementioned discrepancies, the present work shows the results of original field and laboratory analyses aimed at reconstructing the structural setting of both Apulian carbonates and allochton terranes. In particular, two different folding stages and the geometry of the thrust sheets are assessed, by means of detailed field and micro-structural analyses, for the allochton terranes. In the Apulian carbonates, both attitude and kinematics of the syn-sedimentary high-angle faults bounding the Upper Messinian deposits are documented. Furthermore, the tectonic structures associated to the contractional, strike-slip and extensional stages are distinguished based on their abutting and crosscutting relationships. Finally, the results of such a work are discussed in terms of the time-space evolution of deformation in the Monte Alpi area; five main tectonic stages are deciphered for the Pre-Pliocene to Holocene times.

Neogene tectono-sedimentary interaction between the Calabrian Accretionary Wedge and the Apulian Foreland in the northern Ionian Sea

The structural setting of the northern Ionian Sea is the result of the collision between the Calabrian Accretionary Wedge (CAW) and the adjacent foreland, i.e. the Apulian Carbonate Platform. The CAW represents a sector of the Apennine accretionary system extending in the Ionian Sea, bounded to the west by the Malta Escarpment and to the east by the Apulia Escarpment. This work presents the results of the interpretation of new seismic and bathymetric data acquired on the north-eastern edge of the CAW, in the N-Ionian Sea. The data interpretation has identified four main structural domains from NE to SW: 1. The Apulian carbonate Platform consisting of foreland shelf and transitional Mesozoic-Cenozoic carbonate deposits; 2. A narrow foredeep basin, filled by a very thick Plio-Quaternary succession; 3. A deformed domain, at the front of the CAW, incorporating thrusted foredeep sequences and a carbonate block of the Apulian Platform (Transpressed Apulian Block, TAB); 4. A highly deformed pre-Pliocene accretionary wedge. A mid-Pliocene unconformity interpreted on both the CAW and Apulian Foreland suggests that a regional tectonic event occurred at that time, related to the evolution of Calabrian Arc, moving on the subducting oceanic Ionian slab before the collision. This event would correspond to a main tilting and faulting phase of the Apulian Foreland during the diachronous oblique collision with the CAW. The collision and the presence of a remnant of Ionian foreland at the southern front of the accretionary prism, caused a gradual transition to a transpressional tectonics which produced the uplift of the TAB. The TAB would be the south-east continuation of the Amendolara ridge transpressed structure, which forms the offshore extension of the Pollino range. This transpressed shear zone involving the Apulian Foreland developed above the transition between the Adriatic continental crust and the subducting Ionian oceanic crust.

Global versus regional influence on the carbonate factories of Oligo-Miocene carbonate platforms in the Mediterranean area

The Oligocene-Miocene is a key interval that was characterized by a cooling trend associated with a progressive decrease of atmospheric CO2 concentrations that ends in the Present days.In the Central Mediterranean area, during this interval, three main carbonate platform domains developed in the foreland zone of the Apennines: the Latium-Abruzzi-Campana and Apulia domain in the central and south-eastern sectors of the chain and the Hyblea and Pelagian carbonate platforms in the south and south-western sectors. This work analyzes the impact and interplay of global and regional factors controlling the development of different carbonate factories and facies associations over the Chattian and the early Messinian time interval. Three well-studied examples of the central Mediterranean will be used: the Chattian ramp of Malta, the Latium-Abruzzi ramp, and the Bolognano ramp within the northern portion of the Apulian carbonate platform (outcropping on Majella Mountain).The Malta ramp represents the reference model for the heterozoan Oligo-Miocene carbonate factory, since it developed far from terrigenous input, in persistent oligotrophic conditions, and within a tropical climate. In contrast, the evolution of the central Apennine ramps is strictly related to the geodynamic evolution of the Apennines and simultaneously to global oceanographic changes.The Chattian Apennine ramps are affected by a basin conformation that favored the development of dominant currents and related dune fields. Successively, these ramps were exposed to strong Aquitanian volcanism that induced a shift towards an aphotic-dominated carbonate factory. Since the Burdigalian the development of the Apennines has affected the evolution of the investigated ramps through the eastward migration of foredeep systems and related nutrient input. This influence becomes more evident between the Tortonian and Messinian, during which reef-rimmed platforms developed in the rest of the Mediterranean while red algae still dominated in the Apennine ramps. Amongst the global events, the C-cycle perturbation, occurring between the late Burdigalian and Serravallian (Monterey event), leaves a clear sign on the two Apennine ramps.

Structural inheritance controlling active crustal deformation in the Val d'Agri area (southern Apennines, Italy): new insights from finite element modelling

The availability of a large amount of surface geological data and subsurface information gathered by the oil industry, together with seismic and geodetic data, allowed us to define and analyse the active structures in the Val d'Agri area of the southern Apennines. Taking into account that the study of interseismic deformation can be significant to identify locked fault areas that can potentially slip, in this study we present 2D elastoplastic finite-element models to reproduce interseismic characteristics of the study area. This hosts the largest Europe's onshore oil field and is characterised by an active extensional tectonic regime, as inferred from earthquake focal mechanisms and fault slip data from late Quaternary structures. Based on high-quality seismic profiles tied with deep well logs, we constructed a detailed geological section across the study area. Outcropping units are dissected by numerous brittle structures that formed at various stages during the tectonic evolutionof the Apennines, while the deep ones are dominated by deeply rooted major faults. The rheological behaviour has been constrained by the reconstruction of the thermal structure of the fold and thrustbelt, using available information from the foreland Apulian Platform and from temperature data from a series of wells. Starting from the geological model, we reproduced interseismic deformation by means of finite-element numerical modelling, varying boundary conditions and unlocking different fault segments. Our numerical models provide new insights into the controversial and widely debated active tectonic setting of the Val d'Agri area, confirming the major role played by structural inheritance and reactivation processes. In fact, recent low-magnitude seismicity tends to illuminate fault segments consisting of pre-existing reverse faults reactivated as normal faults in the present-day stress field.These long-lived, mature fault systems occurring in the buried Apulian Platform carbonates (and underlying basement) represent major brittle structures that cumulated displacements of up to a few kilometres over geologic time. As a result of their reactivation within the late Quaternaryextensional stress field, these long-lived crustal structures are capable of nucleating also moderate- to large-magnitude earthquakes. The decoupling between deep and shallow structural levels, and the different inherited structures affecting them, explain the apparent contrast between the subdued surface expression of active fault systems and the known occurrence of large magnitude seismic events in the study area, thus reconciling apparently contrasting geological and geophysical constraints.

Extensional reactivation of a deep transpressional architecture: Insights from sandbox analogue modeling applied to the Val d’Agri basin (Southern Apennines, Italy)

The structural framework of the Val d’Agri region results from the superposition of different deformation events over time. In this area, the largest European onshore oil field was discovered in the 1980s, and since then, much geologic and geophysical data have been collected. However, the structural complexity and the poor quality of subsurface data have prevented a full understanding of fault evolution and kinematics so far. In this study, scaled sandbox analogue models have been used to better understand the role of syn-rift inheritance in the present-day structural architecture and to test different possible mechanisms of interaction between inherited transpressional structures at depth and newly formed extensional fault systems at shallow levels during regional quaternary extensional tectonics. Analogue models included two consecutive sinistral transpressional phases deforming the basement and the overlying Apulian Platform carbonates, affected by preexisting northeast–southwest-oriented extensional fault zones. The third phase of the experiments consisted of extensional reactivation of the previously formed transpressional structures. Different kinematic solutions were used to investigate the causal relationships between deep and shallow deformation structures. The very good similarity between the experimental results and the natural prototype strongly supports the presence at depth of a main northeast–southwest-oriented syn-rift extensional fault zone, which was affected by positive inversion during the transpressional deformation of the Apulian Platform below the Val d’Agri area. Comparison of experimental results with fault patterns interpreted on available seismic lines indicates that, despite that no direct connection from deep to shallow faults has been recognized, some structural control of the fault pattern at depth on the evolution of the Val d’Agri quaternary extensional fault systems at shallow depth is possible. Extensional deformations at depth can be accommodated by newly formed faults or by the extensional reactivation of inherited high-angle transpressional fault zones.

Middle Eocene seagrass facies from Apennine carbonate platforms (Italy)

Two stratigraphic sections located in the Latium-Abruzzi (Monte Porchio, Central Apennines, Central Italy) and in the Apulian carbonate platform (S. Cesarea-Torre Tiggiano, Salento, Southern Italy) were measured and sampled to document the sedimentological characteristic and the faunistic assemblages of Middle Eocene seagrass deposits.The faunistic assemblages are dominated by porcellaneous foraminifera Orbitolites, Alveolina, Idalina, Spiroloculina, Quinqueloculina, Triloculina and abundant hooked-shaped gypsinids, associated with hooked red algae and green algae Halimeda. Fabiania, rotaliids and textulariids as well as nummulitids are subordinated. The samples were assigned to Lutetian (SBZ13–16) according to the occurrence of Nummulites cf. lehneri, Alveolina ex. gr. elliptica, Idalina berthelini, Orbitolites complanatus, Slovenites decastroi and Medocia blayensis. At Santa Cesarea reticulate nummulites occur in association with Alveolina spp. and Halkyardia minima marking the lower Bartonian (SBZ17).Three main facies associations have been recognised: I) larger porcellaneous foraminiferal grainstones with orbitolitids and alveolinids deposited into high-energy shallow-water settings influenced by wave processes that reworked the sediments associated with a seagrass; II) grainstone to packstone with small porcellaneous foraminifera and abundant permanently-attached gypsinids deposited in a more protected (e.g., small embayment) in situ vegetated environment; III) bioclastic packstone with parautochthonous material reworked from the seagrass by rip currents and accumulated into rip channels in a slightly deeper environment.The biotic assemblages suggest that the depositional environment is consistent with tropical to subtropical vegetated environments within oligotrophic conditions.

Bedding-parallel stylolites in shallow-water limestone successions of the Apulian Carbonate Platform (central-southern Italy)

Bedding-parallel stylolites typically represent the product of chemical compaction (overburden weight-induced pressure solution) experienced by carbonate successions during their burial history, when bedding is still horizontal. Due to their common occurrence in carbonate rocks, with lateral extents that can exceed 1 km, bedding-parallel stylolites are of special interest for the hydrocarbon industry because they may affect the regional fluid flow in the subsurface. Aimed at assessing the development and distribution of bedding-parallel stylolites in shallow-water, platform limestone successions, field and laboratory studies were carried out on Cretaceous limestones originally pertaining to the Apulian Carbonate Platform realm and now exposed in three distinct Italian locations: Maiella Mountain, Gargano Promontory and Murge Plateau. Results point to a prominent role played by the geological characteristics of limestones on development and localization of bedding-parallel stylolites within shallow-water, platform limestone successions. In particular, bedding-parallel lamination and fine rock grain size, co-occurring in stromatolitic limestones, determined there laterally more extensive and closely spaced stylolites than in the associated calcilutites and calcarenites. Large fenestral pores, which are ubiquitous in stromatolitic limestones, represent rock heterogeneities able to influence the roughness of individual stylolites. Laboratory measurements revealed that the permeability of the studied Cretaceous limestones is very low (<10 μD). Pilot tests suggest that bedding-parallel stylolites in stromatolitic layers are not barrier to fluid flow but may represent pathways through low-permeability, platform limestone successions in the subsurface.