Southern Apennines Thrust Belt Research Articles

The role of inherited structural anisotropies during co-seismic surface faulting: The Pescopagano fault case study (Irpinia seismogenic area, Southern Italy)

Co-seismic failure can occur on newly formed or on inherited structures. However, understanding their surface pattern is challenging when pre-existing structural anisotropies control rupture propagation. We focus here on the Pescopagano Fault (PF), considered part of the extensional fault system that ruptured during the 1980, Mw 6.9 earthquake in Southern Italy. Although the mainshock fault (Irpinia Fault) produced ∼ 40 km of NW-SE trending ground ruptures, these were not observed on a buried antithetic fault located to the northeast of the main fault and defined solely by seismological data. The PF studied here is part of an exposed fault array that spatially coincides with the trace of the antithetic fault. To better assess existing seismotectonic models for the Irpinia fault system, we investigated: i) whether ground ruptures occurred on the PF during past earthquakes, and ii) to what degree surface and deep faults are linked. Paleo-seismological trenches document that the PF has not released surface-rupturing earthquakes during the last ∼13–20 ka. Structural data suggest that the PF developed to accommodate the relaxation of a Pliocene thrust-fold system after the demise of thrusting. Results of this work highlight that the PF may be an inherited Pliocene or Early Pleistocene structure that does not reach the ∼10–15 km seismogenic depth typical of this region. In this scenario, the upward propagation of the antithetic fault from seismogenic depths towards the surface during a 1980-type earthquake may be impeded by a mélange layer developed during the growth of the Southern Apennines thrust belt and interposed between the deep antithetic fault and the upper crustal faults. We cannot exclude, however, that the PF may be activated during very large but infrequent and non-characteristic earthquakes on the Irpinia fault system.

Landslides and predisposing factors of the Southern Apennines, Italy

ABSTRACT The Fiumarella di Corleto drainage basin is an emblematic sector of the southern Apennine thrust belt in the Basilicata region (Southern Italy), which is strongly affected by landslides. Landslides both affect the urban area and the facilities related to hydrocarbon exploitation, such as the pipelines and oil wells connected with the oil centre located just outside the eastern border of the study area. Based on a detailed field survey, supported by stereoscopic analysis, a landslide inventory map has been realized, which also reports the associated processes and landforms. The relationships between the different types of landslides and the various predisposing factors like outcropping lithologies, slopes steepness, slope exposition and land use have been also investigated. The acquired data relate to a geologically complex area of the southern Apennines subject to recent uplift and represent a fundamental contribution useful for the correct management of the territory.

Revitalizing exploration and redevelopment of deep carbonate targets in the Southern Apennines thrust belt (southern Italy): reappraising vintage data with modern approaches

Abstract Hydrocarbon distribution in the Southern Apennines thrust belt of Italy is directly related to the geological characteristics and complex evolution of the thrust tectonic pile involving units from different palaeogeographical domains. Within this structural–stratigraphic context, the main exploration target is represented by the carbonate units of the Apulian Platform, which contain the largest and deepest oilfields in the region. By integrating different types (e.g. wells, seismic, maps, reports) of legacy public and confidential data of various vintages, the subsurface structural setting of the contractional Apulian structures around the Benevento Field in the Southern Apennines hydrocarbon province is reconstructed. The discovery dates back to the early 1970s. The reservoir consists of Cretaceous–Lower Miocene carbonates at a depth of around 3000 m below sea level bearing both oil and gas. A new digital interpretation and integration, which takes into account the most recent understanding of the evolution of this thrust belt, has allowed reconstruction of the trap style of the Benevento Field and of the prospective (undrilled) structures in the surrounding area. A history of positive inversion tectonics is interpreted from a 2D kinematic restoration; this has important implications for both the structural style and the hydrocarbon prospectivity of the Southern Apennines thrust belt.

Geological Features and Physical and Mechanical Properties of the Gorgoglione Building Stone of Basilicata (Southern Italy)

Since prehistoric times stones have been widely employed in the construction of historic buildings, floors, and claddings in rural and urban areas. Among the Italian natural stones, the sandstone belonging to the Gorgoglione Formation, known as the Gorgoglione Stone, quarried and worked near the homonymous village in Basilicata (Southern Italy), is usually used as a building material. The Gorgoglione Stone consists of well-cemented turbidite sandstones deposited in a Middle–Upper Miocene thrust-top basin unconformably resting on the external nappes of the Southern Apennine thrust belt. In the Gorgoglione area, it can be observed in either numerous natural outcrops or quarries. This study aims to highlight the geological peculiarities of the Gorgoglione Stone and, in particular, it is focused on its mechanical characterization for assessing the most effective use when employed in construction, such as public and civil buildings, road construction, paving, and small works of art. Based on the experimental results, obtained by samples collected from different quarries, axial stress–strain curves have been plotted, whose analysis has delivered the deformation behavior and the strength characteristics of the stone. The elastic modulus, uniaxial compressive strength, and axial strain at stress peak have been estimated for several specimens. The measured values are typically of a medium–high-strength sandstone. The tested specimens of sandstone exhibit a typical behavior of an elastic-brittle rock, characterized by a linear path and a failure typically of axial splitting. With regard to the results of the physical tests, they showed that the analyzed sandstone is characterized by quite low density and by medium–high porosity and water absorption.

A Geological Itinerary Through the Southern Apennine Thrust Belt (Basilicata\u2014Southern Italy)

The proposed geological itinerary connects a series of impressive outcrops distributed between the front and the inner portion of the Southern Apennine thrust belt. It offers the opportunity to visit some of the most interesting and best-exposed Southern Apennine geosites, inserted within landscapes typical of the different sectors of the thrust belt, in order to illustrate its geological evolution. The itinerary has been designed in such a way as to intersect different stacked tectonic units and a great variety of sedimentary successions whose age ranges from Triassic to Pleistocene. Each of the chosen geosite contains multidisciplinary geological information that may be of interest for researchers, but may be also appreciated by a general public interested in geology. In particular, the stratigraphy, the structural geology and the geomorphology are the most recurrently treated topics. Most of these outcrops extend for many hundreds or thousands of metres and include villages or mountain reliefs. Therefore, every single site can be considered as an areal geosite containing particular geological features. However, the largest geosite can also be observed in a panoramic view from suitable locations. Thus, each of these sites provides different evidence and when combined together provides an opportunity to understand the complex geological history of the Southern Apennines. The motivation for establishing this itinerary mostly resides in the great scientific interest of the chosen outcrops; this will hopefully facilitate their conservation and the development of geotourism.

The influence of climate variability and land use variations on the occurrence of landslide events (Subappennino Dauno, Southern Italy)

The aim of the paper is to describe the results of the application of a methodology based both on the use of time series analyses and of geospatial analyses of monthly climatic data (rainfall, wet days, rainfall intensity, and temperature), annual maximum of short-duration rainfall (from 1 hour to 5 days), and historical modification of land use in order to characterise the effects of these variables on the occurrence of landslide events. The methodology was applied in the Subappennino Dauno area, located on the eastern margin of the Southern Apennines thrust belt (southern Italy). Despite the decreasing trend of rainfall and rainfall intensity and the increasing trend of temperatures and wet days, there is an increasing trend of landslide occurrence, highlighting the negative effect of anthropogenic modifications and the mismanagement of landslide-prone areas. This hypothesis was confirmed by comparing the distribution of landslides with the land use variations data (especially urban areas and wooded areas) collected from 1930 to 2006.

Stratigraphic and provenance evolution of the Southern Apennines foreland basin system during the Middle Miocene to Pliocene (Irpinia-Sannio successions, Italy)

The paper deals with original stratigraphic, petrographic and structural data concerning the evolution of the southern Apennines chain (Italy). The main Langhian to Pliocene deposits cropping out in the northern sector of the southern Apennines foreland basin system (Sannio-Irpinia area) have been studied and correlated in order to document the effects of tectonic changes on the evolution of sandstone detrital modes and stratigraphic architecture. The studied sandstone units can be grouped in five key intervals: a) Numidian Flysch, mostly formed by Langhian mature quartzarenitic deposits and conformable Serravallian post-Numidian successions, formed by arkosic and calciclastic arenaceous-pelitic beds (foreland depozones); b) Langhian to Tortonian San Giorgio Fm., mostly composed of quartzofeldspatic sandstones (foredeep depozone); c) Tortonian to Early Messinian, quartz-feldspatic and partly sedimentary-carbonatoclastic petrofacies, thrust-top successions (Vallone Ponticello, Villanova del Battista and San Bartolomeo fms.); d) Late Messinian quartzolithic to quartzofeldspatic sandstones (Torrente Fiumarella, Anzano Molasse and Tufo-Altavilla unit), which can be referred to infilled thrust-top basins; e) unconformity-bounded Pliocene quartzofeldspatic sandstone strata (wedge-top depozones), characterized by synsedimentary tectonic activity.Detrital modes of the Serravallian through Middle Pliocene sandstones of the southern Apennines foreland basin system testify clear provenance relations from the accreted terranes forming the southern Apennine thrust-belt. The studied clastics show almost the same blended (quartz-feldspatic) composition; this condition could be related to the tectonic transport over thrust ramp of source rocks, as suggested by the tectonic evolutionary model. This study, dealing with sedimentary provenance analysis and tectonostratigraphic evolution, provides an example of the close relations between clastic compositions and foreland basin system development in southern Apennines.

The Geological Itinerary of Sasso di Castalda: A Journey into the Geological History of the Southern Apennine Thrust-belt (Basilicata, Southern Italy)

Sasso di Castalda (20 km south of Potenza in the Southern Apennines thrust-belt) is a village situated on spectacular outcrops of Mesozoic rocks. In order to illustrate the peculiar stratigraphic and structural features of the area, a geological itinerary comprising 15 stops has been developed around the Sasso di Castalda village. The itinerary illustrates the Mesozoic stratigraphy of the deep-sea Lagonegro Basin in an area where the Triassic to Cretaceous evolution of the basin has been studied in great detail. Extensive exposure allows the observation of tectonic structures related to the Miocene to Pleistocene evolution of the Southern Apennine orogeny. The choice of Sasso di Castalda as the starting point for this itinerary is due to the following reasons: (1) the opportunity to observe the thick sedimentary infill of the Lagonegro Basin, within deeply incised natural sections where lithology, stratigraphical contacts and the geometry of the sedimentary bodies are magnificently exposed; (2) the opportunity to examine 3D-fold geometry at different scales; and (3) the opportunity to observe well-exposed post-orogenic faults crosscutting the earlier contractional structures. The itinerary can be used for school teaching purposes at different levels, as well as university courses. In addition, non-geologists frequently follow the itinerary, often guided by expert volunteers.

Tectonic and eustatic controls on Pliocene accommodation space along the front of the southern Apennine thrust-belt (Basilicata, southern Italy)

The stratigraphical organization of the Pliocene thrust-top deposits cropping out at the front of the Southern Apennine thrust-belt has been debated for a long time taking a great importance in the context of the geodynamics of the Central Mediterranean area. During this time, spreading episodes in the Apennine backarc zone alternate with important phases of overthrusting in the thrust-belt. As a consequence, the Pliocene succession appears to be arranged in a series of stacked units, recording the poliphase tectonic history that leads to the building of the front of the southern Apennine thrust-belt. Although there is not yet an accordance on the nature and position of the main unconformities bounding the thrust-top units, all authors agree that the creation of new accommodation space is mainly ruled by contractional tectonics consequent to the eastward nappe propagation according to the Apennine vergence polarity. A detailed geological survey, carried out along a large portion of southern Apennine thrust-belt front, running south of the Vulture volcano, allowed the collecting of new data concerning the basinal-formation mechanisms acting during the sedimentation of Pliocene deposits. From this analysis, it is clear that even if contractional tectonics is the predominant factor controlling the creation or destruction of accommodation space, other mechanisms, as well as wedge uplift-related extensional tectonics and eustasy, could have also played a significant role in the basin accommodation. In order the considered sector of southern Apennines can provide an useful example about the complex phenomena occurring at mountain belt front where the accommodation space results from a concomitance of eustatic and tectonic factors mainly linked to the accretionary wedge activity.

Integrated interpretation of seismic and resistivity images across the «Val d'Agri» graben (Italy)

Val d'Agri is a «recent SSW - NNE graben» located in the middle of the Southern Apennines thrust belt «chain» and emplaced in Plio-Pleistocene.The recent sedimentation of the valley represents a local critical geophysical problem. Several strong near surface velocity anomalies and scattering degrades seismic data in different ways and compromises the seismic visibility. In 1998, ENI and Enterprise, with the contribution of the European Community (ESIT R & D project - Enhance Seismic In Thrust Belt; EU Thermie fund) acquired two «experimental seismic and Resistivity lines» across the valley. The purpose of the project was to look for methods able to enhance seismic data quality and optimize the data processing flow for «thrust belt» areas. During the work, it was clear that some part of the seismic data processing flow could be used for the detailed geological interpretation of the near subsurface too. In fact, the integrated interpretation of the near surface tomography velocity/depth seismic section, built for enhancing the resolution of static corrections, with the HR resistivity profile, acquired for enhancing the seismic source coupling, allowed a quite detailed lithological interpretation of the main shallow velocity changes and the 2D reconstruction of the structural setting of the valley.

Stratigraphy and Detrital Modes of Upper Messinian Post-evaporitic Sandstones of the Southern Apennines, Italy: Evidence of Foreland-Basin Evolution during the Messinian Mediterranean Salinity Crisis

During the Messinian, the southern Apennines thrust belt experienced a period of strong tectonic rearrangement and accretion, activation of overthrusts, and consequent migration of depocenters. The upper Miocene successions cropping out in the northern segment of the southern Apennine thrust belt have good potential for improving our understanding of the interplay between Messinian salinity-crisis events and foreland-basin evolution. The local Messinian stratigraphy includes: (1) pre-evaporitic thin-bedded euxinic marly clay, interbedded with diatomaceous marls; (2) evaporitic limestone, crystalline gypsum, and reworked gypsum; (3) post-evaporitic deposits subdivided into two main units: the Torrente Fiumarella unit and the Anzano Molasse Formation that grade upward into ostracod-rich deposits (Lago-Mare facies). The evaporitic and post-evaporitic sequences are separated by an angular unconformity. This paper deals with the stratigraphic and petrographic study of the post-evaporitic deposits. The Torrente Fiumarella unit includes lacustrine and alluvial conglomerates, quartzolithic sandstones containing abundant carbonate detritus, shale, and reworked clastic gypsum. The Anzano Molasse Formation includes thick-bedded deltaic to turbiditic conglomerates and sandstones passing upward to thin-bedded turbidite sandstones and marlyclayey siltstones. Sandstones are quartzofeldspathic with variable proportions of sedimentary (both carbonate and siliciclastic) and plutonic detritus. In particular, two populations are present, plutonic-rich and mixed plutonic-sedimentary. Volcaniclastic layers, composed of dominantly vitric particles (shards and pumice), are also interbedded within Anzano Molasse sandstones. The Anzano succession includes rare freshwater ostracods that increase in abundance in the uppermost Lago-Mare facies. The Lago-Mare facies deposits are represented by silty-marly clay with abundant Ostracoda shells (Ilyocypris gibba, Cyprideis torosa and Candona sp.) and intrarenite having abundant intrabasinal carbonate particles (ooids, peloids, and bioclasts) and subordinate extrabasinal noncarbonate and carbonate particles. The post-evaporitic sequences represent an infilled foredeep basin, with a lacustrine environment progressively deepening and experiencing gravity resedimentation. Detrital modes document complex provenance relations from upper Messinian accreted terranes of the southern Apennines thrust belt. Post-evaporitic sandstones in the Irpinia-Daunia sector of the southern Apennines foreland-basin system record both the effects of the foreland tectonic evolution and the Messinian Mediterranean salinity crisis. They may represent alternative models for foreland-basin evolution during a restricted time in late Messinian, which can be applicable also in other portions of the circum-Mediterranean orogen.

The structure and kinematics of substrate entrainment into high‐concentration sandy turbidites: a field example from the Gorgoglione ‘flysch’ of southern Italy

AbstractSandy turbidites commonly show evidence for significant dynamic coupling with their substrate. The resulting deformation can be described using structural kinematic methods, linked to palaeoflow indicators, to better understand the links between flow and entrainment processes. A field example from the syn‐orogenic Gorgoglione Flysch, a succession of upper Miocene turbidites deposited into a deforming array of thrust‐top basins in the southern Apennine thrust belt, Italy, is described. The succession contains metre‐scale packages of alternating sandy turbidites and shales but is notable for containing > 100 m thick, massive sandbodies. These are structureless apart from sporadic horizons of aligned mud clasts. Commonly, the substrate beneath the massive sandbodies is deformed, with minor folds and thrusts verging in the direction of palaeoflow determined from tool marks and flutes at the base of these sandbodies. Structural studies from the base of a selected massive sandbody have identified that the substrate mud has been injected upwards, with flames sheared over in the direction of palaeoflow. Thus the substrate has deformed and become entrained during emplacement of the massive sandy body. At some locations, the substrate can be traced into the overlying deposit, with substrate clay beds becoming boudinaged and entrained into the sandbody. Analysis of the orientation of the mud clasts indicates that this bed disruption and incorporation into the sandy massive‐bed turbidite was an organized, viscous process. These features indicate that significant shear stress was partitioned out of the flow and onto the substrate. The incorporation and disruption of substrate into the sandbody suggest that post‐disruption strains increase upwards – implying that displacement gradients increased into the flow. These behaviours, showing variations in strain partitioning between the flow and its substrate, are explored in terms of evolving flow dynamics and substrate rheology.

An integrated geophysical investigation of the upper crust in the epicentral area of the 1980, Ms=6.9, Irpinia earthquake (Southern Italy)

In this paper, we investigate the upper crustal structure of the Irpinia region, Southern Apennines thrust belt, Italy, through analysis and joint interpretation of gravity data, seismic reflection lines and subsurface information from many deep wells. The investigated region includes the epicentral area of the 1980 ( M s=6.9) Irpinia earthquake and is one of the Italian regions with the highest seismic hazard. The upper crustal structure is imaged by modeling a series of 15 SW-trending gravity profiles, spaced about 5 km apart, plentifully constrained by seismic reflection lines and wells, thus reducing the inherent ambiguity of the gravity modeling. Despite of the complexity of the modeled Bouguer anomalies, the application of a calibrating procedure to constrain the range of variability of the density values, as well as the use of geometric constraints, results in a good level of stability in the final density cross-sections, which in fact appear coherent both in the density values and in the geometrical features. The inferred model shows important lateral density variations that can be mostly related to NW-trending geologic structures. High-density bodies delineate carbonate platform thrust sheets and broad antiforms involving Mesozoic basinal rocks, while low-density shallow bodies are associated with Pliocene basins. In addition, important density (i.e. lithological) variations are evident along the strike of the range, the most relevant being an abrupt deepening of the Apulia Carbonate Platform in the southeastern part of the investigated region. In the epicentral region of the 1980 event, we find that the geometry of the high-density, high-velocity carbonates of the Apulia Platform appears correlated with the distribution of the aftershocks and with the P-wave velocity anomaly pattern as inferred from a previous local earthquake tomography. The structural highs of the Apulia Platform correspond to high-velocity regions, where aftershocks and coseismic slip of the mainshock are concentrated. This correlation suggests that the Apulia Carbonate Platform geometry played an important role in the rupture propagation and in the aftershock distribution.

Active faults at the boundary between Central and Southern Apennines (Isernia, Italy)

This paper focuses on the boundary area between the Central and Southern Apennines thrust belt of the Italian peninsula, which separates two different patterns of distribution of active faults and strong earthquakes along the Apennines chain. In order to reduce the remarkable lack of data on this area, part of this boundary has been investigated. The study area corresponds to the surroundings of the town of Isernia, an important centre of the Molise region, and contains the Carpino and Le Piane (CLP) intermountain Basins of Quaternary age. The research was based on unpublished data, consisting of 65 well logs drilled in the CLP Basins, integrated with detailed field surveys (scale 1:10,000), mesoscale structural analysis and aerial photograph interpretation. This study allowed to define the geometry and kinematics of the CLP Basins. They result to be asymmetric half-grabens partially filled with fluvio-lacustrine deposits, where the sedimentation is controlled by the activity of a set of normal faults striking N30°W and NE dipping. This set of faults, which developed mainly during the Late Pleistocene–Holocene, is about 10 km long and is located close to the northwestern end of the Boiano Basin extensional Fault System. The average slip rate calculated for part of the Holocene for one of the recognised faults ranges from 0.75 to 1.00 mm/year. The identification of the active CLP Basins Fault System partially fills the gap of data at the boundary between the Central and Southern Apennines. From a more general point of view, we hypothesise that this boundary might be regarded as a “persistent segment boundary”, forming a long-term barrier to the propagation of rupture of active fault systems. Under this perspective, a redefinition of the seismic zonation of Italy for the study area is suggested.

Inferences on the upper crustal structure of Southern Apennines (Italy) from seismic refraction investigations and subsurface data

This paper presents an interpretation of crustal seismic refraction data from the northern sector of the Southern Apennines thrust belt, a region that in historical times experienced large destructive earthquakes. The data were acquired in 1992 along a seismic line 75 km long and parallel to the Apenninic chain, in order to determine a detailed 2-D P-wave velocity model of the upper crust in an area that had not been deeply investigated by geophysical methods previously. We have used a 2-D ray tracing technique based on asymptotic ray theory to model travel times of first and reflected P-wave arrivals. Synthetic seismograms have been produced by finite difference simulations in order to check the reliability of the velocity model inferred by ray-tracing modelling. The interpretation of the velocity model is constrained by stratigraphic and sonic velocity logs from wells for oil exploration located close to the seismic line. Gravity data modelling allows to check the velocity model and to extend the structural interpretation in 3-D. In the shallow crust, up to a depth of 3–4 km, strong lateral variations of the modelled velocities are produced by the overlapping of thrust sheets formed by: (1) Cenozoic flyschoid cover and basinal successions that underlie the seismic profile with P-wave velocities in the 2.8–4.1 km/s range and thicknesses varying between 0.5 and 4.5 km; (2) Mesozoic basinal sequences with a velocity of 4.8 km/s and a depth of 1.5–2.1 km in the northern part of the profile; (3) Mesozoic limestones of the Western Carbonate Platform with a velocity of 6.0 km/s and a depth of 0.1–0.8 km in the southern part of the profile. At a greater depth, the model becomes more homogeneous. A continuous seismic interface 3.0–4.5 km deep with a velocity of 6.0 km/s is interpreted as the top of the Meso-Cenozoic Carbonate Multilayer of the Apulia Platform, characterized by an increase in seismic velocity from 6.2 to 6.6 km/s at depths of 6–7 km. A lower P-wave velocity (about 5.0 km/s) is hypothesized at depths ranging between 9.5 and 11 km. As inferred by commercial seismic lines and data from two deep wells located in the Apulia foreland and Bradano foredeep, this low-velocity layer can be related to Permo-Triassic clastic deposits drilled at the bottom of the Apulia Platform. Seismic data do not allow us to identify possible deeper seismic interfaces that could correspond to the top of the Paleozoic crystalline basement; this is probably due to the low-velocity layer at the bottom of the Carbonate Multilayer that reflects and attenuates a great part of the seismic energy. The joint interpretation of seismic refraction and well data, in accordance with gravity data, provides the first detailed P-wave velocity model of the upper crust of the northern sector of the Southern Apennines, which differs considerably from previous 1-D velocity models used to study the seismicity of the region, and reveals new information about the structure of the thrust belt.

Long-term event stratigraphy of the Apulia Platform margin (Upper Jurassic to Eocene, Gargano, southern Italy)

ABSTRACT The Upper Jurassic to Eocene Apulia Platform margin and the eastward transition to the adjacent basinal deposits are well exposed in the Gargano Promontory (southern Italy), a carbonate block that is part of the slightly deformed foreland of the southern Apennine thrust belt. The long-term stratigraphy of this margin and slope transect is punctuated by five major dynamic phenomena that subdivide the succession into six second-order sequences. These events include (1) a Valanginian drowning unconformity, (2) an early Aptian-Albian drowning and demise of the platform, (3) late Albian-Cenomanian platform-margin failures, (4) a Santonian-Campanian retreat of the platform margin, and (5) Eocene uplift and platform-margin collapse. The first event is documented worldwide and is probably eustatic in origin. The second is concomitant with some oceanic anoxic events (OAE). The last three processes are probably related to foreland reaction to subduction and collision in the Dinarides and Hellenides thrust belts. The ultimate cause of the Albian-Cenomanian failures is more problematic. A worldwide eustatic regression is documented at this time, but regional geology seems to favor tectonic uplift.

Provenance and tectonic implications of heavy minerals in Pliocene-Pleistocene siliciclastic sediments of the southern Apennines, Italy

During the late Tortonian-Pleistocene, rifting in the Tyrrhenian region and compression in the Apennines coexisted, with an eastward migration of the rift basin-thrust belt-foredeep systems. In a northwest-southeast area of the southern Apennine Pliocene deposits, accumulated in piggy-back basins, and Pliocene-Pleistocene sediments deposited in the foredeep basins, are contiguous. Here our attention is focused on the heavy minerals, which are sensitive indicators of source rocks. Garnet, blue amphibole, staurolite, clinopyroxene, epidote have been analysed and compared with the minerals of the likely protoliths. Blue amphibole and staurolite derive from Early Miocene ‘Tufiti di Tusa e Arenarie di Corleto’ Formation; pyroxenes derive from Pleistocene Vulture volcanics and, possibly from Pliocene volcaniclastic strata cropping out in Basilicata. Interestingly, blue amphibole and staurolite, present in the Early Miocene volcanolithic and quartzofeldspathic sandstones of the ‘Tufiti di Tusa e Arenarie di Corleto’ Formation, are absent in Tortonian siliciclastic strata, but appear again in Pliocene-Pleistocene siliciclastic sediments. The space-time distribution of these minerals was controlled by important morphostructural modifications affecting the southern Apennine thrust belt.

Tectonic history of the Lagonegro Domain and Southern Apennine thrust belt evolution

The tectonic history of the Lagonegro Domain in Southern Italy is an intriguing topic for the Mesozoic Mediterranean paleogeography and is important for reconstructions of the Tethys. Previous interpretations postulate the paleogeographic position of a deep Lagonegro-Molise-(Sicilide) basinal domain between the external Apulia carbonate platform to the east, and the internal Apenninic carbonate platform (i.e. the Alburno-Cervati-Maddalena Mountains) to the west. A second and separate deep basin more to the west was the home of the Liguride units which cover extensive areas of the Southern Apennines. Following an extensive review of previously published concepts and on the base of the structural interpretation of the Southern Apennines thrust belt using additional subsurface data and extensive field mapping, the authors now suggest that all deep basinal units of the Southern Apennines, i.e. the Ligurides, the Lagonegro units and the Molise-Sicilide units, derive from internal areas located to the west with respect to a coeval wide carbonate platform-slope-shallow-basin complex which, in its pre-Middle Miocene reconstruction, extended from Apulia well beyond the present-day Tyrrhenian coast of Southern Italy. The basinal units were first assembled as an accretionary wedge and overthrusted during the Late Miocene over the carbonate platform-slope-shallow-basin complex. The Liguride-Lagonegro-Molise-(Sicilide) accretionary wedge was later cut by an envelopment thrust which overthrust the previously underlying platform complex over the previously emplaced complex accretionary wedge. Our hypothesis in part revives an old concept proposed by Selli (1962) and requires further testing and research. We conclude that paleogeographic reconstructions of the Southern Apennines and the Mediterranean Tethys are still in a state of flux.

Tectonic Evolution of the Southern Apennines Thrust-Belt (Italy) as Reflected in Modal Compositions of Cenozoic Sandstone

The composition of sandstones derived from erosion of the southern Apennines orogen provides constraints for Cenozoic tectonic evolution. Clastic wedges were derived mainly from the strongly deformed Calabrian arc allochthon. This key tectonic element is interpreted as a thrust sheet of European crust, moved about 300-400 km eastward during the Paleogene to Neogene toward the Adria foreland. During the Paleogene to Early Miocene, the Liguride Complex oceanic terrane was deposited in a remnant ocean basin, east of the Calabrian arc, related to northwestward subduction of Ligurian oceanic lithosphere beneath the European margin. Upper Paleogene quartzofeldspathic and volcanolithic Liguride sandstones testify to provenance from the subduction complex to the magmatic arc, respectively. Upper Oligocene to lower Miocene quartzolithic sandstone suggests a recycled-orogen provenance (i.e., metasedimentary rocks in the growing accretionary Calabrian arc). Final closure of the Liguride remnant ocean basin and onset...

Petroleum geology of the ‘Fossa Bradanica’ (foredeep of the Southern Apennine thrust belt)

Abstract The ‘Fossa Bradanica’ is located in Southern Italy, East of the Apennine mountain chain. It has undergone a complex geotectonic evolution: from platform (Mesozoic carbonates) to unstable foreland (Eocene-Miocene) and finally to foredeep of the Apennine thrust belt (Plio-Pleistocene). Petroleum exploration targets in this province are represented by: (a) Gas and oil in carbonates of the pre-Pliocene substratum. In this domain traps are only structural; (b) Gas and subordinately oil in Plio-Pleistocene sands, where structural, stratigraphic and combination traps can be found. The oils produced range in gravity from 3° to 45° API, with prevailing values of 15–20° API. Two families of oils have been recognized: oils generated by a shaly source deposited in oxygenated waters and oils derived from a carbonate source deposited in a euxinic environment. Most of the oils are classified as non-mature or marginally mature oils. Gas is mostly dry: 79% of the gas discovered in Fossa Bradanica being of biogenic, 6% of thermogenic and 15% of mixed origin. Many fields have high CO 2 concentrations (50 to 90% in the carbonates). The CO 2 content decreases, moving upwards in the stratigraphic column.