1,720,964 research outputs found
Structural investigation of background features and normal faults affecting the Calcari con Selce Formation, Southern Apennines, Italy
No full textThe Calcari con Selce formation (CSf) is a low-porosity multilayer carbonate, partially dolomitized, formation that extensively crops out in the Lucania Apennine chain. This lithostratigraphic succession represents to depth a key formation concerning hydrocarbon exploration and a potential confined acquifer system. In this work we describe the structural features affecting the CSf related to burial and tectonic deformation with emphasis on normal faults related to post-orogenic extensional deformation. A field investigation led to recognition of background structures such as: i) strata-bounded sub-vertical fracture sets (OBj) and bedding-parallel solution seams (BPss), related to lithostatic load; and: ii) oblique-to-bedding solution seams (BOss) induced by syn-orogenic flexural slip. Furthermore, different sets of dolomitic veins extensively affect dolomitized parts of the CSf showing structural relationships with bedding interfaces. Localized low-angle normal faults (LANFs) post-dating the previous structures formed further anisotropies locally associated with sub- vertical fracture sets (SVfs). These structures, enhancing permeability within carbonate beds, promoted fluid compartmentalization. High- angle normal faults and associate fracture sets, characterized by well-connected features, mainly localized along the mature fault zones, further enhanced the permeability of the CSf allowing the development of preferential fluid-flow pathways moving parallel to the fault-zones, as inferred from the structure of calcite veins. This work provides an enhanced characterization of the fracture network affecting the CSf and represents a useful tool aimed at improving hydrological models for fluid circulation within fractured reservoirs
Oblique-slip fault growth by segment linkage: a case from Basilicata, southern Italy
No full textFaults and fractures are the dominant modes by which the upper brittle crust accommodates deformation, and an extensive documentation of their geometrical and kinematic features is critical for a better understanding of how these structures enucleate and evolve through time. The map distribution and cross-sectional profile of macroscopic normal faults suggest that these structures enucleate as smaller isolated segments, and that individual segments are linked to produce larger faults as their tips propagate laterally and down-dip. By contrast, documentation of these relationships in outcrop-scale examples is relatively less abundant, and mesoscopic information on the modes of linkage of isolated fault segments is quite rare: yet, minor structures are often well exposed, thus allowing for a detailed determination of the processes responsible for their development. In this study we document a situation from the Potenza Basin (Southern Apennines, Italy) where a mesoscopic transtensional fault array grew by linkage of smaller isolated fault segments. Observations of the zones of fault segment overlap provide the basis for a kinematic deformation model of stepped ramp-flat fault surface development. Because of the need of investigating at the early stages of faulting, we restricted our analysis to very small structures, where the overprinting relationships among minor fabrics are particularly clear
Evidenze di tettonica estensionale sinsedimentaria pliocenica al fronte della catena appenninica meridionale (Appennino Lucano)
No full textLo studio stratigrafico - strutturale condotto al fronte della catena appenninica meridionale, nel settore lucano, permette di ricostruire le ultime fasi evolutive della catena. In particolare, il ritrovamento di faglie estensionali sinsedimentarie mette in luce che alle fasi tettoniche contrazionali si sono alternate fasi estensionali, probabilmente riconducibili al riaggiustamento isostatico della catena, che hanno localmente prodotto nuovo spazio di accomodamento al di sopra del prisma di accrezione tra il Pliocene inferiore e medio
Geology of the north-eastern margin of the High Agri Valley (western Basilicata, southern Italy)
No full textThis contribution aims at anticipating the results of a recent structural study that has been carried out in the central domain of the Lucanian Apennines in southern Italy. Compilation of an original 1:25,000 scale geological map, integrated with stratigraphic data and structural/kinematic evidence along the NE edge of the Agri Valley, provides critical elements that make it possible to discriminate the effects of recent, seismically active deformations, related to the dissection of the southern Apennine fold-and-thrust belt, from those related to pre-orogenic deformations of Mesozoic age, inherited from rifting and drifting of Adria
3D modeling and cross-section restoration as tools for imaging geological structures
No full textDifferent modelling techniques are used for reconstruct the current (deformed) architectural geometry in tectonically complex areas. We tailored workflows for geological modelling that include the use of georeferred field data, interpreted geological maps and cross-sections; when available, subsurface data like well logs and seismic images are used for better constrain the model. Surfaces representing lithological boundary and faults have been obtained in different ways, either by interpolation of the starting data (field measurements, best constrained map traces of the structures), or starting from reference surfaces (used as a proxy for subsequent morphing by using structural thickness and attitude constraints. Subsequent balancing methods in both cross-section and 3D are used for constrain the geological model with a trial-and error procedure. Our experience demonstrates the effectiveness of the 3D modelling techniques in different tectonic settings. Here we are presenting map-scale examples of models obtained in areas of the inner and the central zones of the Apennines, respectively in areas where the post-collisional extension is prevalent, and areas where the effects of the contraction does. We stress the need of 3D geometrical coherence between geological maps and related cross-sections, and the utility of the 3D modelling and visualization techniques in achieve best results and geometrically consistent linked structures
3D modeling as a tool for imaging geological structures
No full textThe use of three-dimensional (3D) modelling and visualization techniques is an effective tool that helps in the understanding of the geometry and evolution of the geological structures. These techniques are routinely used in the oil & gas and in the mine industries, where significant investments are accompanied by careful planning and monitoring through digital modelling. With the increasing need of understand three- dimensional coherence of large and multidisciplinary datasets, the 3D modelling practice has been extended to field-based investigations and serves as a predictive tool in areas with poor sub-surface data. In the latter case, the study of analogue outcrops is used to predict the 3D behaviour of subsurface structures. Our experience demonstrates the effectiveness of the 3D modelling techniques in different tectonic settings. Here we are presenting map-scale examples of models obtained in areas of the inner and the central zones of the Apennines, respectively in areas where the post-collisional extension is prevalent, and
areas where the effects of the contraction does
Transtensional deformations and oblique-slip fault propagation: an example from the Lucanian Apennine, southern Italy
No full textFaults and fractures are the dominant modes by which the upper brittle crust accommodates deformation, and an extensive documentation of their geometrical and kinematic features is critical for a better understanding of how these structures enucleate and evolve through time. The map distribution and cross-sectional profile of macroscopic normal faults suggest that these structures enucleate as smaller isolated segments, and that individual segments are linked to produce larger faults as their tips propagate laterally and down-dip. By contrast, documentation of these relationships in outcrop-scale examples is relatively less abundant, and mesoscopic information on the modes of linkage of isolated fault segments is quite rare: yet, minor structures are often well exposed, thus allowing for a detailed determination of the processes responsible for their development. In this study we document a situation from the Potenza Basin (Southern Apennines, Italy) where a mesoscopic transtensional fault array grew by linkage of smaller isolated fault segments. Observations of the zones of fault segment overlap provide the basis for a kinematic deformation model of stepped ramp-flat fault surface development. Because of the need of investigating at the early stages of faulting, we restricted our analysis to very small structures, where the overprinting relationships among minor fabrics are particularly clear. The present investigation represents the methodological continuation of two earlier contributions and aims at comparing the results from fault analysis in the Potenza Basin with those recently obtained for the high Agri Valley
1:25.000 Geological map and cross sections of the north-eastern margin of the High Agri Valley (Basilicata - Italy)
No full textThis study aims at investigating the controlling factors of repeated inversion and fault-reactivation phenomena, both positive and negative, within orogenic domains. The study has been carried out in the seismically and tectonically active Agri Valley basin, in the axial zone of the southern Apennines of Italy. Fieldwork was based on the compilation of an original 1:25.000 scale geological map of about 120 Kmq, on the construction of cross sections, and on the kinematic analysis of the major tectonic structures outcropping along the NE edge of the Agri Valley. One key feature outlined by this new survey is the recognition and mapping of the Sorgente dell’Acero Member, a stratigraphic unit that previous workers had only described as part of the Calcari con Selce Formation. Furthermore the present research provides important constraint on the study of active tectonics in the High Agri Valley. In order to characterize the recent faults and develop a correct census of the sismogenic structures it is fundamental to reconstruct a correct sequence of tectonic events that occurred in the area, separating the effects of fossil from those of active structures
The History of the Southern Apennines of Italy Preserved in the Geosites Along a Geological Itinerary in the High Agri Valley
No full textThe itinerary presented in this paper links several geosites and proposes a series of geostructural and geomorphological observations
that illustrate the cyclical character of the orogenic processes. The itinerary crosses the northern corner of the High Agri
Valley, a 200-km2-wide area of outstanding geological importance located along the axial sector of the Southern Apennine of
Italy. Its history is the result of the succession of extensional and contractional deformation phases that allowed the deposition of
sediments, the formation and deformation of rocks, the growth and the fragmentation of an orogenic system during the last 250
MA. The aim of the study is to bridge scientific and educational values of the High Agri Valley area by examining its geological
and geomorphological features, which have been fundamental in shaping the landscape, and determining the geological resources
and the natural hazards, highlighted through the itinerary. Despite its outstanding natural beauty, over the years, the investigated
area has suffered the pressure of diverse human activities, including a growing industrial development related to hydrocarbon
exploration and production, often leading to conflicting interests and severe landscape damage. As a result, environmental and
geoconservation aspects of this area have been at the centre of regional and national debates. In the light of these issues, this work
aims at providing a better understanding of the geological and geomorphological value of the High Agri Valley area, in order to
strengthen the basis for setting-up a sustainable geoconservation plan, which includes geotourism issues
Structural inheritance, growh and dissection in a fold-and-thrust belt: a case from western Lucania, southern Italy
No full textIn this contribution we anticipate the results of a structural investigation carried out along the central sector of the Apennines fold-and-thrust belt of western Lucania, southern Italy. The data inferred from this study made it possible to reconstruct the complete deformation history of the central province of the southern Apennine belt, where documentation of well-constrained deformation episodes is integrated with recognition of previously unreported structures. The study area is located between the Melandro and Agri valleys, and comprises the villages of Savoia di Lucania, Vietri di Potenza, Marsico Vetere and Viggiano. From Late Miocene time onwards thrusting was followed bythe onset of extensional deformations that overprinted contractional structures and migrated progressively towards the front of the belt.
The most recent structures related to the extensional episode are high-angle normal faults that are clearly visible along the northeastern edge of the Agri Valley. These faults are replaced to the south by left-lateral strike-slip faults, analogue to those described at the Lucania-Calabria boundary. High-angle normal faults truncate and offset at least two older generations of tectonic contacts, that dip at moderate to low angles producing mainly extensional displacements. At odds with older thrusts and with more recent high-angle normal faults, the kinematics of these low-angle tectonic contacts is not always well-constrained, and thus their tectonic significance remains problematic. Observations carried out in the northern edge of the Agri valley strongly support the hypothesis that these contacts are, in fact, low-angle normal faults, although a thrust origin for analogue structures found elsewhere in the investigated area cannot be ruled out
- …
