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Stratigraphic and structural relationships between Meso-Cenozoic Lagonegro basin and coeval carbonate platforms in southern Apennines, Italy

Abstract Stratigraphic studies and facies analysis integrated with a new geological and structural survey of the Meso-Cenozoic units outcropping in the Campania–Lucania Apennines, southern Italy, allowed us to restore the palaeogeographic pattern and the tectonic evolution of the chain during Oligo-Miocene times. The southern Apennines are a N150°-striking and NE-verging fold-and-thrust belt mainly derived from the deformation of the African–Apulian passive margin. Four wide belts with different features have been recognized in the chain area. From east to west the following units outcrop: (a) successions characterized by basinal to marginal facies, ranging in age from Cretaceous to Miocene, tectonically lying on Plio-Pleistocene foredeep deposits; (b) successions characterized by shallow-water, basinal and shelf-margin facies, ranging in age from middle Triassic to Miocene (‘Lagonegro units’), overthrust on the previous ones; (c) Triassic to Miocene carbonate platform successions (‘Apenninic platform units’), overthrust on the Lagonegro units; (d) Jurassic–Cretaceous to Miocene deep-water successions (ophiolite-bearing or ‘internal’ units and associated siliciclastic wedges), outcropping along the Tyrrhenian belt and the Calabria–Lucania boundary, overthrust on the Apenninic platform units. All these units tectonically lie on the buried Apulian platform which is covered, at least in the eastern sector of the chain, by Pliocene to Pleistocene foredeep deposits. Stratigraphic patterns of the Cretaceous to lower Miocene Lagonegro successions are coherent with the platform margin ones. Calcareous clastics of the Lagonegro basin are in fact supplied by an adjacent western platform, as inferred by several sedimentological evidences (slump and palaeocurrent directions and decreasing grain size towards the depocentre of the basin). Tectonic relationships among the different units of the chain — with particular emphasis on the Lagonegro and Apenninic platform units of the Lucanian segment — are shown by means of both regional and detailed geological cross-sections. The Lagonegro units constantly underlie the carbonate units originating from detachment and thrusting of the western platform and overlie the eastern (i.e. Apulian) platform. The Lagonegro units show a strong lateral variability of map-scale structures. Dome-and-basin folds are in fact largely observable in the Lucanian Apennine. Further, the belt is widely affected by Plio-Quaternary strike–slip and extensional faults. Yet, excluding the brittle deformation due to Quaternary faulting, the complexity of structural styles seems to result from the Neogene refolding of more ancient structures produced by Oligo-Miocene intraplate deformation. This hypothesis is supported by two independent lines of evidence: the first is the recognition of unconformities between the lower Miocene Numidian sandstone and the underlying Lagonegro successions, at least in the southwestern sectors; the second is that the internal (i.e. western) platform remains undeformed until the early Miocene. Both stratigraphic and structural data suggest an external position of the Meso-Cenozoic Lagonegro basin with regard to the coeval Apenninic platform.

Hydraulic properties of fault zones in porous carbonates, examples from central and southern Italy

We present the results of in situ permeability measurements performed, using a portable field permeameter, on normal and strikeslip fault zones that crosscut high-porosity carbonate grainstones. The measurement sites expose in the Cretaceous Orfento Formation of the Majella Mountain (Abruzzo, Italy), and the Lower Pleistocene deposits of the Favignana Island (Sicily, Italy). Nine small-displacement, compactive shear banding-based fault zones have been tested in the field. The fault offset ranges between 10 and 200 centimeters. The acquired permeability data indicate a two orders of magnitude decrease of porosity and permeability from the host rock to the cataclastic fault cores. A clear dependence of the fluid circulation paths through porous carbonates is therefore inferred at depth due to orientation, density and connectivity of the fault zones. Moreover, this study indicates the key role played by the pore network characteristics (pore dimensions above all) of undeformed host rocks on determining extremely different permeability values of the faulted porous carbonate grainstones. Accordingly, the results presented in this study may be helpful in applications such as geofluids management for improving the forecasting of carbonate reservoir quality and understanding the extent of reservoir compartmentalization.

Repeated reactivation in the Apennine-Maghrebide system, Italy: a possible example of fault-zone weakening?

Abstract Italy owes its complex geological structure to a double switch in tectonic regime, which involved the opening of the Tethys Ocean during Early Mesozoic time, its closure leading to development of the Apennine-Maghrebide fold-and-thrust belt during the Eocene-Recent interval, and the post-orogenic opening of the Tyrrhenian Sea since Miocene time. This history of tectonic inversion is partly preserved within two major fault zones, the Valnerina Line, in the central Apennines, and the Gratteri-Mount Mufara Line, in central-northern Sicily, which were repeatedly reactivated with different kinematic characters. The relatively long life of these structures indicates that strain was localized along anisotropies inherited from early deformation episodes. However, the progressive widening of both fault zones through time may result from strain-hardening fault-rock behaviour during subsequent deformations, thus suggesting that fault reactivation does not imply fault-zone weakening as is often assumed.

A regional‐scale discontinuity in western Sicily revealed by a multidisciplinary approach: A new piece for understanding the geodynamic puzzle of the southern Mediterranean

The results of an integrated stratigraphic, structural, geophysical, and geochemical study reveal the presence of a crustal discontinuity in western Sicily that, at present, runs roughly N-S along a band from San Vito Lo Capo to Sciacca (SVCS). The boundary between the two zones of this discontinuity is nearly orthogonal to the main thrust propagation of the Sicilian thrust-and-fold belt. The different Permian to Tertiary sedimentary evolution recorded by the two zones appears related to this discontinuity, with thick carbonate platforms in the western sector facing deep-water successions in the eastern one. The presence of Upper Triassic reefs, huge megabreccias bodies, and widespread submarine volcanisms along the transition zone suggest the presence of a long lasting weakness zone. This zone has been reactivated episodically as transpressional and/or transtensional faults in relation to the different geodynamic stress acting in central Mediterranean area in different epochs. We speculate that this transition zone has represented a segment of the passive margin of the Ionian Tethys. During the Maghrebian convergence a different style of deformation has affected the two sectors floored by different sedimentary multilayers. The orthogonal-to-oblique differential convergence between the two sectors has resulted in right-lateral transpressional motions, leading to oblique thrusting of deep-water-derived thrusts onto platform-derived thrusts associated with clockwise rotations. The oblique convergence is still ongoing as demonstrated by the seismicity of the area, by the geothermal field with high mantle-derived helium fluxes and by the GPS measurements collected by different authors.

The southern Tyrrhenian Sea margin:an example of lithospheric scale strike-slip duplex

The southern Tyrrhenian Sea margin is dominated by deformations nwhose kinematics are relatively poorly constrained, and different nmodels have been proposed to account for its recent evolution. Analysis nof new structural and space geodesy data, combined with available ngeophysical information, reveal a deformation field characterised by nsubhorizontal NW-SE directed shortening and SW-NE directed extension. nThe main recognised regional-scale structure comprises E-W ntrending fault zones, namely the Ustica-Eolie Line and the Mt. Kumeta-Alcantara Line, connected by the NW-SE trending Marettimo, nTrapani, San Vito, Palermo, Gratteri-Mt. Mufara and Eolie nfaults. This fault network displays a remarkable dextral strike-slip ncharacter, and has the features of a strike-slip duplex, that we indicate nas the Southern Tyrrhenian Strike-Slip Duplex (STSSD). Analysis of navailable geophysical data and regional considerations based on platetectonic nreconstructions suggest that the STSSD is a primary feature nof lithospheric-scale importance. Our strike-slip duplex model differs nsignificantly from previously proposed passive margin interpretations nfor the Tyrrhenian Sea margin offshore northern Sicily. The results of nthis investigation show the effectiveness of an integrated, multidisciplinary napproach in the study of active deformation margins

Active faults and inferred seismic sources in the San Vito lo Capo peninsula, northwestern Sicily, Italy

Abstract Two independent active faults, capable of generating medium-sized earthquakes in the San Vito lo Capo peninsula, northwestern Sicily (Italy) have been identified as a result of detailed field studies. In western Sicily, instrumental seismicity is low; in fact, except for the 1968 Belice earthquake (Ms = 5.4), historical records indicate that this area is relatively quiescent. Most of the seismicity is in the offshore sector of the Sicilian Maghrebian Chain, which is characterized by several medium- to low-magnitude events. The main shock of the 2002 Palermo seismic sequence (Mw = 5.9) represents the largest earthquake felt in the area in recent years. The deformation pattern characterizing the most recent faults mapped in northwestern Sicily includes a grid of high-angle faults consisting of major east-west-striking right-lateral and north-south-striking left-lateral features. This fault grid is related to a regional transcurrent right-lateral shear zone, here named the UEKA shear zone, bounded to the north by the Ustica-Eolie fault and to the south by the Kumeta-Alcantara fault. The UEKA shear zone accommodates the regional strain induced by the current stress field acting in the area, which, as emerges from both structural and seismological data, is characterized by a NW-SE-striking main compression.

MIDDLE TRIASSIC (LADINIAN) DEEP-WATER SEDIMENTS IN SICILY. NEW FINDINGS FROM THE MADONIE MOUNTAINS

A section of carbonate megabreccias grading upward to deep-water Daonella limestones is described from the locality of Sant’Otiero, near Petralia Sottana, in the Madonie Mountains (Sicily). The megabreccia mainly consists of neritic elements containing dasycladalean algae ( Diplopora annulatissima Pia) along with benthic foraminifers and problematics. The overlying calcilutitic strata are characterized by lumachella intercalations containing the bivalve Daonella tyrolensis Mojsisovics suggesting an early Late Ladinian ( Protrachyceras longobardicum ammonoid zone) age. We informally name the Daonella limestone as the calcare di Sant’Otiero (Sant’Otiero limestone). The Daonella limestones along with the neritic megabreccia extraclasts with Diplopora annulatissima represent a previously unknown component of the pre-Carnian stratigraphy from the paleo-Alpine Sicily.

LANDFILL SITE SELECTION FOR MUNICIPAL SOLID WASTE BY USING AHP METHOD IN GIS ENVIRONMENT: WASTE MANAGEMENT DECISION-SUPPORT IN SICILY (ITALY)

The goal of this work was to test a methodology, based on multi-criteria analysis and geographic information systems, aimed at identifying areas potentially suitable to host landfills for Municipal Solid Waste (MSW). Although the above-mentioned methodology was applied to three different areas (Western, South-western and Eastern) of Sicily, in this paper, we present the results of the western sector. The first step consisted of the division of the study area in excluded and potentially suitable sites, on the basis of the Italian current legislation. The suitable sites were subsequently re-evaluated based on additional criteria in order to choose the most suitable ones. This second step consisted of a multi-criteria analysis based on a scores and weights system. The Analytic Hierarchy Process (AHP) was applied to estimate the relative importance weights of the evaluation criteria. The suitability for landfill siting was finally evaluated with the aid of a simple additive weighting method. The resulting land suitability was reported on a scale of 0 to 10, respectively, from the least suitable to the most suitable sites. In order to reveal the most suitable sites, to provide a ranking and, consequently, a quick selection, a spatial clustering process was carried out. In relation to the data obtained, several suitable areas to host sites for MSW landfill in Western Sicily were identified. The application of multi-criteria analysis, together with the use of geographic information systems, provided a powerful tool for the identification of the most suitable site among those identified.

Extensional deformations during Neogene chain building in Sicily

In the Madonie-Nebrodi Mts (Northern Sicily belt) both Mesozoic carbonate platform/basin-derived deformed successions and Neogene foredeep deposits outcrop. Thrust sheets piled-up southwards in thin-skin piggy-back sequence. The chain building process began during the Oligo-Miocene. The syntectonic deposits involved in the compressional tectonics give evidence that syn-sedimentary extensional faults developed during fold nucleation and amplification. Syn-sedimentary extensional faults affect the foredeep strata at different stratigraphic levels, which are bounded by unconformities. Normal faults and bedding show constant cut-off relationships and are progressively tilted youngwards as the effect of thrust-related folding. Since their formation, these normal faults have locally interacted with the thrust geometry by means of positive inversion within the older strata and with physically connected to reverse faults crosscutting the succession youngwards.