Maurizio Parotto

Gravimetric evidence of deep structure in mountain building: Subducted Adriatic crust beneath the Tyrrhenian Moho in Central Italy

Abstract A possible first-order model of the deep structure underneath Central Italy is provided, taking into account a possible subduction mechanism, by means of updated gravimetric and revised geological and geophysical data. In order to produce a gravimetric model some elements are assumed: the surface geological setting, a deformed basement and the generally accepted depths to the Moho. For the gravimetric model presented here, Bouguer anomaly values (constant density of 2.4 g cm − ) from the Italian National Gravimetric Data Base have been used (the data base is on a 3 × 3 km rectangular net). The model has been tested on a geological cross-section and matching calculated gravity and observed gravity. The two curves show a regional negative gradient from the Tyrrhenian towards the Adriatic side, with a minimum central depression corresponding to the core of the Apenninic chain. The general negative slope of the curve suggests mantle densities lower in the western than in the eastern part of the model. This can be justified by taking into account the values of heat flow and the spreading of the Tyrrhenian Sea. The minimum corresponding to the central part of the chain is modelled assuming a wedge of low density in the upper mantle. This wedge is interpreted as part of a slab of Adriatic lithosphere subducting towards the Tyrrhenian Sea.

An integrated methodology of viticultural zoning to evaluate terrains suitable for viticulture: the test area of Cesanese DOC (Latium, central Italy)

The increase in the world wine market has required continued improvements in viticultural zoning in both old and young production regions. The many proposed zoning methods vary according to the study area in which they are applied as well as to the perspective of the authors. Thus, there is little agreement on which factors (climate, landscape, geology, soil and human intervention) should be taken into account. The aim of this work is to provide a methodology to optimize and possibly increase the development of wine production regions, identifying the zones with different potential suitability. We coupled the computation of bioclimatic indices based on Géoviticulture Multicriteria Climatic Classification System with a GIS (geographic information system) analysis based on the integration of easily accessible geological, morphometric and geomorphological data, in addition to viticulture land use. The final result of this methodology is a suitability map distinguishing sectors of different suitability for wine production in a vine cropping area. We tested the methodology on the Cesanese DOC (Denomination of Origin Verified) zone (Latium, central Italy). The resulting suitability map indicates that the areas more favourable for viticulture are only partially exploited, encouraging the possibility of increasing the production of high-quality wine in the Cesanese DOC area. This result underlines the applicability of our methodology in land-use planning and management.

Geometry and kinematics of the Montelanico-Carpineto Backthrust (Lepini Mts., Latium) in the hangingwall of the early Messinian thrust front of the central Apennines: implications for the Apennine chain building

The paper updates knowledge on the Montelanico-Carpineto Backthrust, which is confined in the Lepini Mts. thrust sheet, at the hangingwall of the Neogene Latina Valley Thrust Front. The local stratigraphic setting consists of a pre-orogenic succession of Mesozoic carbonates from the Latium-Abruzzi platform Auct. The carbonates are paraconformably overlain by Miocene ramp limestones, which evolve upwards into planktonic marls. The Sub-Ligurian unit thrusted over this dominantly carbonate succession. In the Latina Valley, siliciclastic turbidites (Frosinone Formation Auct. ), which evolved from the above-mentioned Miocene units, constitute the upper Tortonian foredeep deposits, now preserved in the footwall of the Lepini Mts. thrust sheet. In the Segni-Montelanico area, conglomerates, unconformably overlying the carbonate bedrock and coeval with the Frosinone Formation, are interpreted as late Tortonian thrust-top deposits (Gavignano and Gorga unit). The Lepini Mts. ridge has two series of distinctive tectonic features: the first is related to the Neogene shortening events due to the Apennine chain building; the other results from Plio-Quaternary extensional events associated with the collapse of the Tyrrhenian margin. The Montelanico-Carpineto Backthrust, as evidenced by the structural survey, is a compressive fault plane dipping 45°–50° towards NE with a SW-verging dip-slip kinematics. The fault has an offset of about 700 m, ramp geometries and a cut-off of about 20°. The Montelanico-Carpineto Backthrust and the Latina Valley Thrust Front define a pop-up structure. The presumable age of the Montelanico-Carpineto Backthrust is the early Messinian, because the late Tortonian Gavignano and Gorga unit is involved in its brittle shear zone. This implies that the formation of the Montelanico-Carpineto Backthrust and of the related pop-up structure is coeval with the early Messinian thrusting of the Lepini Mts. thrust sheet upon the geodynamic propagation of the central Apennine chain-foredeep-foreland system.

Schema strutturale della catena a pieghe e sovrascorrimenti Umbro-Sabina (Italia Centrale) derivato dal rilevamento dei fogli 366 “Palombara Sabina” e 375 “Tivoli” (Progetto CARG)

Structural Scheme of the Umbria-Sabina fold-and-thrust belt (Central Italy) derived from the geological mapping of 366 Palombara Sabina and 375 Tivoli sheets (CARG Project).The geological mapping of the sheets 366 Palombara Sabina and 375 Tivoli (1: 50.000 scale; CARG Project; in preparation) allowed the revision of the structural setting of the westernmost portion of this part of the Neogene fold-and-thrust belt of the Central Apennines.The area comprises the Cornicolani, Lucretili, eastern Sabini, Tiburtini, Ruffi and Prenestini Mts (Latium region). Most of the area (Cornicolani, Lucretili and Tiburtini Mts) is made of the pre-orogenic deposits (Upper Triassic-Serravallian) referred to the calcareous-marly-siliceous Sabina Succession, that were accumulated in the southern part of the Umbria-Marche-Sabina Pelagic Basin (Sabina Domain), proximal to the Latium-Abruzzi Carbonate Platform. In general, in the eastern areas, more proximal to the platform, coarser lithofacies crop out. Moreover, in the Cornicolani and western Lucretili Mts (Castelvecchio Mt) areally restricted outcrops of condensed pelagic carbonates (Bugarone Group and calcari dolomitici di S. Angelo Romano) document the occurrence of Jurassic intrabasinal structural highs evolved into Pelagic Carbonate Platforms. These structural highs were generated after the Early Jurassic rifting, that broke-up the pre-existing carbonate platform (Calcare Massiccio).In the mapped area, the Latium - Abruzzi Platform is represented in the hangingwall of the Olevano-Antrodoco line only in the southern Prenestini Mts (Rocca di Cave), by upper Cretaceous shelf carbonates. Whereas in the footwall of the Olevano-Antrodoco line it crops out along the Aniene River valley. Both Sabina and Latium - Abruzzi successions are overlain by upper Tortonian - lower Messinian marls and siliciclastic syn-orogenic deposits, best observed in the easternmost areas and inbetween the Ruffi and Prenestini Mts.In their turn, the syn-orogenic deposits are unconformably overlain by post-orogenic Plio-Pleistocene marine clastic deposits and Quaternary volcanic and alluvial sediments. From a structural point of view, the Sabina Domain is arranged into several thrust sheets verging toward the east, developed in middle-late Miocene-early Pliocene times. The early Pliocene Olevano-Antrodoco out-of-sequence thrust marks the eastern tectonic boundary of this structural domain where the pelagic and slope sediments overthrust the Latium - Abruzzi Carbonate Platform and its associated syn-orogenic deposits. In late Miocene-early Pliocene extensional tectonics down-threw the western border of this imbricated structure enhancing the marine ingression along the peri-Tyrrhenian margin. The western border of the region was also reactivated by N-S right-lateral strike-slip fault dissecting the earlier structures in Pleistocene times.From top of the orogenic edifice three main tectonic units have been identified:- Unit 1 (Morra Mt) made up of Upper Triassic to Lower Jurassic dolomite limestones (Dolomia Principale) and Calcare Massiccio, overthrust onto unit 2.- Unit 2 (comprising Cornicolani Mts, western Lucretili Mts) made up of Dolomia Principale, Calcare Massiccio, Corniola detritica and, in the Cornicolani and western Lucretili Mts, Bugarone Group. Long wavelength upright folds mainly characterize this unit and faults with high angle cuts-offs prevail, and Jurassic structural highs occur (Cornicolani Mts, Castelvecchio Mt).- Unit 3 (comprising Elci Mt, eastern Lucretili Mts and Tiburtini Mts) made up of most of the Sabina basin stratigraphic succession - from Corniola detritica Fm. to the Guadagnolo Member (marly lithofacies); the unit is characterized by NW to NE verging overturned to recumbent folds.- Unit 4 (comprising Prenestini Mts, Ruffi Mts and eastern Sabini Mts) made up of the upper portion of the basin succession between the Marne a Fucoidi and Upper Miocene siliciclastics and the Rocca di Cave carbonate platform succession.This unit is made up by two sub-units, based on the deformation-style and stratigraphy: the sub-unit 4A (Granaro Mt, Colle Serviano and Arzillo Mt in the western Prenestini Mts), is mainly characterized by east-verging packed asymmetrical folds with sub-vertical axial-planes, and N-S striking dextral-transpressive faults. The sub-unit 4B (Castel Madama area, eastern and central Prenestini Mts, Ruffi Mts and eastern Sabini Mts) is characterized by a wide symmetrical anticline in the western portion, and by folds with very steep axial planes, and N-S to NNW-striking dextral transpressional faults.The units are separated by low-angle thrusts or by high-angle transpressive faults: the stratigraphic successions characterizing each unit rejuvenate eastward. The innermost unit 1 and unit 2, where massive or poorly stratified deposits are exposed, are mainly deformed by high angle faults. Whereas the more external unit 3 and unit 4 are composed by alternating carbonate, marls and siliciclastics, and are mostly characterized by east-verging slightly to strongly asymmetrical and overturned folds.A new geometric and kinematic scenario for the Neogene evolution of the units preserved in the hangingwall of the Olevano-Antrodoco thrust is here outlined.The revision of the stratigraphy and structural data put in evidence the presence of paleo-structures of the Tethyan passive margin not evidenced in the past cartography, their influence on Neogene compressive structures and the coexistence of non-coaxial structural trends in areas of limited extension.