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It is unanimously acknowledged that the Corsica‐Sardinia microplate rotated counterclockwise (CCW) by 40–50° between 21 and 15 Ma, synchronous with Liguro‐Provençal Basin oceanic spreading. Conversely, 60–120° CCW rotations with respect to Europe from Sardinia (Permian dykes, volcanics and sediments, Mesozoic carbonates, and lower Eocene limestones) have been interpreted to be related to (a) late Permian intra‐Pangea shear events, (b) Aptian Iberia rotation, and (c) Eocene Valais Ocean closure. We report paleomagnetic data from 31 red‐bed sites from the mid‐late Eocene (45–32 Ma) Cixerri Fm. exposed in SW Sardinia. Characteristic paleomagnetic directions from 25 dual polarity sites (240 samples) define an 86 ± 7° CCW rotation. We suggest that a S Sardinia block located NE of Balearic Islands rotated 30° CCW during the 30–21 Ma Liguro‐Provençal rifting, and was decoupled from N Sardinia along the left‐lateral Nuoro fault. After 21 Ma, Corsica‐Sardinia underwent a drift‐related 60° CCW rotation as a whole. A re‐analysis of available paleomagnetic results shows that Permian data from N Sardinia‐Corsica align with European directions considering a 60° CCW rotation, whereas Permian and mid Jurassic data from S Sardinia match European directions only after considering a ∼35° CCW Iberia rotation besides the 90° post‐Eocene event. We suggest that S Sardinia was part of Iberia, and rotated CCW during both Aptian Iberia drift and Oligo‐Miocene Liguro‐Provençal opening. Our data, along with recent paleomagnetic results from Calabria, suggest that S Sardinia, Balearic Islands, Calabria, Peloritan, Kabylies, and Alboran were fragments of "Greater Iberia," joined to Iberia before 30 Ma Liguro‐Provençal rifting. Key Points: Mid‐late Eocene Cixerri Fm (SW Sardinia) rotated ∼90° counterclockwise (CCW); Permian data from S Sardinia and N Sardinia‐Corsica rotated CCW by 120 and 60°S Sardinia rotated 35 and 90° during Iberia rotation and Liguro‐Provençal rift; N Sardinia‐Corsica rotated 60° during Liguro‐Provençal driftIberia, S Sardinia, Balearic Islands, Calabria, Peloritan, Kabylies and Alboran formed Greater Iberia before 30 Ma [ABSTRACT FROM AUTHOR]

The structural analysis of large intracontinental wrench faults is fundamental for deciphering the long-term evolution of continental crust in complex areas in terms of their geodynamic evolution and large-scale crustal block displacements. In this contribution, we demonstrate a pre-Miocene dextral activity of the present-day left-lateral Great Kavir - Doruneh Fault System (GKDFS, Central Iran), one of the major intracontinental active strike-slip faults extending from the Afghan border to the Nain region between Central Iran and the Sanandaj-Sirjan Zone. We document important dextral shearing recorded along a segment of the GKDFS, the Arusan Fault System (AFS), located east of Jandaq, close to the present-day active trace of the GKDFS. The AFS include several ENE-WSW striking strands exposed for a length of more than 50 km, which couple pre-Cretaceous ophiolites and metamorphic basement units with the Cretaceous succession of the Khur basin. The fault shows transpressional structures consistent with a dextral shear including thrusts and en échelon folds affecting the Cretaceous carbonate units. Paleostress reconstruction based on mesoscopic fault analysis and related folds geometry allowed to establish vorticity parameters indicating that deformation occurred close to a total simple shear regime with a calculated Wk between 0.9 and 1. The enormous Meso-Cenozoic dextral displacements occurred along the AFS and along the entire GKDFS are attested by the up to several hundreds of kilometers offset of the Paleotethys suture zone, from NE Iran to the western border of Central Iran. [ABSTRACT FROM AUTHOR]

The timing of Quaternary uplift evolution of the Simbruini range (Central Apennines, Italy) is poorly known due to the lack of reliable chronological constraints of the post‐orogenic continental clastic units, deposited after the upper Messinian thrust‐top facies, and tectonic events. In this regard, we identified the main geomorphic markers, including several levels of continental units, whose plano‐altimetric projection along the river longitudinal profile has been correlated with the main non‐lithological knickpoints. Furthermore, we inferred the uplift history of the range by applying the inverse modeling of the river longitudinal profiles. Assuming a block uplift model, the drainage network cutting the Simbruini range recorded 2.4 ± 0.5 Ma of tectonic history, characterized by variable base‐level fall rates (corresponding to variable uplift rates). [ABSTRACT FROM AUTHOR]

The Boiano Basin is one of the largest Quaternary intermontane basins of the central‐southern Apennines within one of the most tectonically active areas of the Mediterranean region. In order to reconstruct its entire Quaternary stratigraphic, tectonic, and palaeoenvironment evolution, lithofacies and palaeomagnetic analyses have been performed on a 900 m‐deep borehole (CP1) drilled in the southwestern sector of the basin. The Quaternary succession consists of an alternating of alluvial fan and fluvial–marshy deposits for a total thickness of 240 m, unconformably laying on Lower Miocene deposits of the Sannio Unit, thrusted on upper Miocene deposits of the Molise Flysch. In addition, the stratigraphic study and facies distribution of 29 intermediate and shallow wells drilled in the basin, allowing us to define the thickness and lithofacies variations of the Quaternary sedimentary units inside the entire Boiano Basin in the sector of Campochiaro alluvial fan. Our results demonstrate that the Boiano Basin infilling started during the late Early Pleistocene (c. 1.1 Ma) and developed with variation in lithofacies distribution and thickness. The first depositional unit (Early Pleistocene–early Middle Pleistocene in age) was palustrine and fluvial–marshy, the second (Middle Pleistocene in age) was characterized by the occurrence of the first cycle of alluvial fan deposition, the third (late Middle Pleistocene in age) was newly palustrine and fluvial marshy and, finally, the fourth recorded two cycles of alluvial fan deposition (late Middle Pleistocene and Late Pleistocene in age, respectively), interspersed by short periods of palustrinity, tephra layers deposition, and palaeosols development. The study allows the hypothesizing that the Quaternary infilling was accommodated within a graben (or semigraben) structure, affected mainly by extensional fault systems localized in the inner part of the basin and secondly by fault systems bounding the basin. [ABSTRACT FROM AUTHOR]

Sedimentary basins in the interior of orogenic plateaus can provide unique insights into the early history of plateau evolution and related geodynamic processes. The northern sectors of the Iranian Plateau of the Arabia-Eurasia collision zone offer the unique possibility to study middle-late Miocene terrestrial clastic and volcaniclastic sediments that allow assessing the nascent stages of collisional plateau formation. In particular, these sedimentary archives allow investigating several debated and poorly understood issues associated with the long-term evolution of the Iranian Plateau, including the regional spatio-temporal characteristics of sedimentation and deformation and the mechanisms of plateau growth. We document that middle-late Miocene crustal shortening and thickening processes led to the growth of a basement-cored range (Takab Range Complex) in the interior of the plateau. This triggered the development of a foreland-basin (Great Pari Basin) to the east between 16.5 and 10.7 Ma. By 10.7 Ma, a fast progradation of conglomerates over the foreland strata occurred, most likely during a decrease in flexural subsidence triggered by rock uplift along an intraforeland basement-cored range (Mahneshan Range Complex). This was in turn followed by the final incorporation of the foreland deposits into the orogenic system and ensuing compartmentalization of the formerly contiguous foreland into several intermontane basins. Overall, our data suggest that shortening and thickening processes led to the outward and vertical growth of the northern sectors of the Iranian Plateau starting from the middle Miocene. This implies that mantle-flow processes may have had a limited contribution toward building the Iranian Plateau in NW Iran. [ABSTRACT FROM AUTHOR]

We report on results from anisotropy of magnetic susceptibility (AMS) analyses carried out on weakly deformed fine-grained sediments from the Northern Apennine orogenic system (Italy). We sampled 63 sites from preorogenic, synorogenic, and postorogenic sequences, which differ in age, composition, depositional environment, degrees of deformation, and tectonic regimes. The magnetic fabric is typical of weakly deformed sediments, with a magnetic foliation subparallel to the bedding plane and a magnetic lineation well defined in this plane. Northern Apennine chain deposits are characterized by strongly oblate magnetic susceptibility ellipsoids, indicating that the magnetic fabric is the result of both compaction process and tectonic load experienced by the sediments during diagenesis and orogenic events. The orientation of magnetic lineation is significantly different depending whether the studied sites underwent extensional or compressional tectonic regimes. In the Northern Apennine chain, the magnetic lineation is mostly oriented NNW-SSE, parallel to the main compressional structures. It suggests a tectonic origin of the magnetic lineation with an acquisition related to the Apennines compressional phases. In the extensional Tuscan Tyrrhenian margin, magnetic lineation is oriented ENE-WSW, almost perpendicular to the main extensional faults, which represent the main deformation elements of the area. Our results demonstrate a close relationship between the shape and orientation of magnetic fabric and the tectonic history of rocks, confirming that AMS represents a valuable tool to investigate the tectonic history of weakly deformed sedimentary rocks. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study we use the anisotropy of magnetic susceptibility (AMS) and paleomagnetic data for deciphering the origin of magnetic lineation in weakly deformed sedimentary rocks and for evaluating oroclinal processes within the Arabia-Eurasia collision zone. In particular, we have analyzed the Miocene Upper Red Formation (URF) from the outer curved front of the southern Central Alborz Mountains of north Iran, to test for the first time with paleomagnetic data the origin (primary versus secondary) of this orogenic arc. AMS data document the existence of a magnetic lineation parallel to the orientation of the major tectonic structures, which vary along strike from WNW to ENE. These directions are highly oblique to the paleoflow directions and hence suggest that the magnetic lineation in the URF was produced by compressional deformation during layer-parallel shortening. In addition, our paleomagnetic data document clockwise and anticlockwise rotations along vertical axis for the western and eastern sectors of the Central Alborz Mountains, respectively. Combined, our results suggest that the orogen represents an orocline, which formed not earlier than circa 7.6 Ma most likely through bending processes caused by the relative motion between the rigid crustal blocks of the collision zone. Moreover, our study provides new insights into the Iran-Southern Caspian Basin kinematic evolution suggesting that the present-day SW motion of the South Caspian Basin with respect to Central Iran postdates oroclinal bending and hence cannot be as old as late Miocene to early Pliocene but a rather recent configuration (i.e., 3 to <1 Ma). [ABSTRACT FROM AUTHOR]

This multidisciplinary study conducted in the area covered by sheet 348 'Antrodoco' of the Geological Map of Italy contributes to the knowledge on an undissected intermontane basin located at the transition between the Gran Sasso and the Laga structural-paleogeographic domains in the highly seismic Apennine axial zone. Geomorphological analysis is used to infer the role of extensional faults and to provide a relative chronology of the capture phenomena that have led to a substantial reduction of the catchment area since the Early Pleistocene. Geophysical and stratigraphic data have been integrated into a 3D model, enabling evaluation of the thickness and geometry of the Quaternary sedimentary infilling. A stratigraphic study, chronologically constrained according to paleomagnetic results and C datings, highlights the occurrence of a major unconformity related to changes in the drainage network and suggests that during the Early Pleistocene, the Montereale Basin experienced an initial aggradation phase conditioned by the activity of local tectonic structures and then evolved under the influence of prevailing external factors. Finally, this study represents a complete and integrated approach. This approach makes possible, for the first time, the imposition of a number of firm constraints on the geometry and evolution of this under-explored intermontane basin, located in a key position along the Apennines. [ABSTRACT FROM AUTHOR]

We report on an extensive paleomagnetic study (36 sites) of the Tuscan Nappe succession from the Northern Apennines Arc, aimed to reconstruct the tectonic evolution of the internal sector of this chain. We analyzed Eocene pelagic foreland ramp deposits (Scaglia Toscana Formation) and Oligocene-lower Miocene siliciclastic turbidites (Macigno and Falterona Formations). Paleomagnetic results show that the internal sector of the Northern Apennines underwent large counterclockwise (CCW) rotations with respect to the Adria-Africa foreland. A decrease in the rotation magnitude was observed from the southern to the northern sector of the arc (from 91 to 36°). This trend is opposite to that observed in the more external units of Northern Apennines and demonstrates that the oroclinal bending model, which has been proposed for the external units of the chain, is not appropriate to explain the evolution of the internal sector of the arc. On the basis of the observed paleomagnetic pattern, we propose a new tectonic model in which the Tuscan and Falterona-Cervarola units in the southern area were first rotated CCW along with the Corsica-Sardinia block during its lower Miocene rotational drifting and were later involved in the main phases of rotational emplacement and translation toward the outermost sector (Umbria domain), thus yielding the final curved shape of the Northern Apennines chain. Data from this study represent the first paleomagnetic evidence of the influence of the Corsica-Sardinia CCW rotation in the Apennines orogenic wedge deformation, in the general framework of the geodynamic evolution of the Central Mediterranean subduction system. [ABSTRACT FROM AUTHOR]

In this paper, new paleomagnetic and anisotropy of magnetic susceptibility (AMS) data from Miocene continental units of the Çankırı Basin are presented, with the main goal of providing additional constraints on its deformational and rotational history during the Late Cenozoic. AMS data indicate a tectonic origin for the magnetic fabric, suggesting that Upper Miocene units were still involved in the deformation processes. Paleomagnetic data show that tectonic rotations in the Çankırı Basin do not show a symmetrical distribution along the opposite edges of the basin, as expected from the observed H-shape. In particular, by combining our data with those already published, we observe that tectonic rotations increase from the southern portion of the basin toward the north and from the central part toward the basin margins. This distribution reasonably matches with a post-Late Miocene reactivation of the Çankırı Basin margin fault systems, possibly related to the activity of the right-lateral North Anatolian strike-slip fault. In this tectonic interpretation, the complex pattern of paleomagnetic rotations appears to be connected with a local block rotation mechanism due to the activity of faults with strike-slip components of motion along the tectonic margins of the Çankırı Basin. [ABSTRACT FROM AUTHOR]

One of the major issues for understanding the tectonic evolution of continental regions is how pre-existing discontinuities influence the style and distribution of deformation, which is often not obviously and uniquely connected to the plate-boundary kinematics. Iran represents one of the most instructive regions to study continental deformation, as here the present-day Arabia–Eurasia convergence is accommodated in a very wide area over a range of structures. The tectonic boundary between the Lut and the Tabas blocks of Central Iran currently accommodates part of the Arabia–Eurasia convergence by right-lateral strike-slip faults, associated with NNW–SSE oriented fold-related thrust. During Middle-Late Jurassic, this boundary was the location of a large-scale shelf-lagoon carbonate platform-slope-to-basin depositional system, mainly controlled by the activity of a N–S oriented normal fault system. In this study, the geometry and the kinematics of the deformation at the tectonic boundary between the Lut and the Tabas blocks, are reconstructed from an integrated anisotropy of magnetic susceptibility (AMS) and structural analysis in the Upper Jurassic Garedu Red Beds Fm., outcropping at the core of a NNE–SSW oriented syncline in the northern Shotori Range. AMS and structural results indicate that the Upper Jurassic Garedu Red Beds Fm. syncline can be defined as a transected fold, where the mismatch between fold hinge and magnetic fabric/cleavage is about 15° counter-clockwise, suggesting that this fold system formed as a consequence of right-lateral transpressional tectonics. Results from this study thus document the evolution of Jurassic normal faults to a transpressional tectonic boundary between the Tabas and Lut crustal blocks sometime between the Lower Cretaceous and Palaeocene. [ABSTRACT FROM AUTHOR]

Anisotropy of magnetic susceptibility (AMS) analysis has been carried out in the thermometamorphic aureole surrounding the Late Miocene Monte Capanne pluton (Elba Island, Central Italy). The identification and separation of the main carriers of the magnetic susceptibility by low-temperature and high-field AMS measurements demonstrate that a correct knowledge of the magnetic fabric is needed in order to use AMS for tectonic interpretations. Magnetic fabric data, combined with structural data from the aureole, and their comparison with data from the pluton itself, were used to constraint the mode of pluton emplacement. Results document an intimate linkage between the magmatic flow pattern and the syn-metamorphic fabrics acquired during pluton emplacement in the host rocks. The magnetic/structural fabric in the aureole rocks is dominated by flattening deformation and no systematic relationship with any regional tectonic feature is observed. These results suggest that local processes induced by magma ascent in the upper crust might have played a primary role in space generation for pluton emplacement in the Tuscan Magmatic Province, suggesting a revaluation of the modes of pluton emplacement during the post-orogenic evolution of the northern Apennine system as a whole. [ABSTRACT FROM AUTHOR]

Estimates of pyroclastic flow emplacement temperatures in the Cerro Galán ignimbrite and Toconquis Group ignimbrites were determined using thermal remanent magnetization of lithic clasts embedded within the deposits. These ignimbrites belong to the Cerro Galán volcanic system, one of the largest calderas in the world, in the Puna plateau, NW Argentina. Temperature estimates for the 2.08-Ma Cerro Galán ignimbrite are retrieved from 40 sites in 14 localities (176 measured clasts), distributed at different distances from the caldera and different stratigraphic heights. Additionally, temperature estimates were obtained from 27 sample sites (125 measured clasts) from seven ignimbrite units forming the older Toconquis Group (5.60-4.51 Ma), mainly outcropping along a type section at Rio Las Pitas, Vega Real Grande. The paleomagnetic data obtained by progressive thermal demagnetization show that the clasts of the Cerro Galán ignimbrite have one single magnetic component, oriented close to the expected geomagnetic field at the time of emplacement. Results show therefore that most of the clasts acquired a new magnetization oriented parallel to the magnetic field at the moment of the ignimbrite deposition, suggesting that the clasts were heated up to or above the highest blocking temperature ( T) of the magnetic minerals ( T = 580°C for magnetite; T = 600-630°C for hematite). We obtained similar emplacement temperature estimations for six out of the seven volcanic units belonging to the Toconquis Group, with the exception of one unit (Lower Merihuaca), where we found two distinct magnetic components. The estimation of emplacement temperatures in this latter case is constrained at 580-610°C, which are lower than the other ignimbrites. These estimations are also in agreement with the lowest pre-eruptive magma temperatures calculated for the same unit (i.e., 790°C; hornblende-plagioclase thermometer; Folkes et al. ). We conclude that the Cerro Galán ignimbrite and Toconquis Group ignimbrites were emplaced at temperatures equal to or higher than 620°C, except for Lower Merihuaca unit emplaced at lower temperatures. The homogeneity of high temperatures from proximal to distal facies in the Cerro Galán ignimbrite provides constraints for the emplacement model, marked by a relatively low eruption column, low levels of turbulence, air entrainment, surface-water interaction, and a high level of topographic confinement, all ensuring minimal heat loss. [ABSTRACT FROM AUTHOR]

This paper illustrates a geographic information system (GIS) supported methodology for the assessment of landslide susceptibility. The methodology involves four operational steps: survey, site analysis, macroarea analysis and susceptibility analysis. The Survey includes the production (or acquisition) of a large-scale litho-technical map, a large-scale geomorphological map, a detailed inventory of past and present landslide events, and a high resolution DTM (Digital Terrain Model. Site analysis leads to the definition of discriminating parameters (commonly, lithological and morphometric conditions necessary but not sufficient to trigger a landslide of a given type) and predisposing factors (conditions that worsen slope stability but are not sufficient to trigger a landslide of a given type in the absence of discriminating parameters). The different predisposing factors are subdivided into classes, whose intervals are established by descriptive, statistical analysis of landslide inventory data. A numerical index, based on the frequency of landslide occurrence, quantifies the contribution of each class to slope instability. [ABSTRACT FROM AUTHOR]

Abstract: The historical site of the Monte Mario lower Pleistocene succession (Rome, Italy) is an important marker of the Pliocene/Pleistocene boundary. Recently, the Monte Mario site was excavated and restudied. A spectacular angular unconformity characterizes the contact between the Monte Vaticano and the Monte Mario formations, which marks the Pliocene/Pleistocene boundary. Biostratigraphical analyses carried out on ostracod, foraminifer, and calcareous nannofossil assemblages indicate an Early Pliocene age (topmost Zanclean, 3.81–3.70 Ma) for the underlying Monte Vaticano Formation, whereas the Monte Mario Formation has been dated as early Pleistocene (Santernian, 1.66–1.59 Ma). Palaeomagnetic analyses point to C2Ar and C1r2r polarity chrons for the Monte Vaticano and the Monte Mario formations, respectively. The Monte Mario Formation consists of two obliquity-forced depositional sequences (MM1 and MM2) characterized by transgressive systems tracts of littoral marine environments at depths, respectively, of 40–80 m and 15–20 m. The data obtained from foraminifer and ostracod assemblages allow us to reconstruct early Pleistocene relative sea-level changes near Rome. At the Plio/Pleistocene transition, a relative sea-level drop of at least 260 m occurred, as a result of both tectonic uplift of the central Tyrrhenian margin and glacio-eustatic changes linked to early Pleistocene glaciation (Marine Isotope Stage 58). [Copyright &y& Elsevier]

Paleomagnetic data collected in the last 30 years indicate that a simple orocline model is not sufficient to describe the complex evolution of the Calabrian Arc. Present-day curvature of the Calabrian Arc is the result of a different tectonic history between the edges of the arc, namely the Southern Apennines and Sicily, and its core, the Calabria-Peloritani Domain. These differences mirror the structural architecture and deep lithospheric configuration of the Calabrian Arc, which are related to the geometry and evolution of the Ionian subduction system. In particular, the presence of lateral heterogeneities in the subducting lithosphere and the subsequent progressive decrease in width of the trench during subduction are likely the main causes of Calabrian Arc formation and of its present-day narrow tight shape. [ABSTRACT FROM AUTHOR]

The Hyblean Plateau in southeastern Sicily, Italy, consists of an isolated and elevated forebulge structure formed since the early Miocene time by bending the foreland lithosphere below the advancing Maghrebian thrust-fold belt. The Hyblean forebulge is presently located in front of an orogenic recess and partly surrounded by two orogenic salients. We analyzed magnetic (anisotropy of magnetic susceptibility) and structural (joints, faults, slickenside lineations, and bed attitudes) fabric data from Neogene carbonate rocks exposed atop the Hyblean forebulge. Results showed unidirectional fabrics developed in response to a NW-SE extension at the end the of early Miocene time and beginning of middle Miocene time, and duple-to-multiple fabrics developed in response to major NW-SE and NE-SW extensions from the Langhian time onward. We interpreted these results as the evidence for the growth of a doubly plunging forebulge due to the presence of foreland crustal heterogeneities, which enhanced differential retreating processes of the foreland along the subduction zone and the subsequent formation of orogenic salients and recesses. A semianalytical model shows that the observed brittle deformations potentially involved a significant thickness of the carbonate sedimentary cover, thereby reducing the lithosphere flexural rigidity and enhancing its bending aptitude. [ABSTRACT FROM AUTHOR]

Combined structural and petrographical investigations, coupled with 40Ar/39Ar geochronology, were carried out in the Sila Piccola Massif of the Calabrian Arc in order to define the structural geometry and map out the major structural and metamorphic breaks within the exposed nappe sequence. On the basis of the contrasting Alpine pressure-temperature ( P- T) and structural signatures the nappe stack can be divided in two major tectonic complexes, bounded by a flat-lying ductile to brittle extensional shear zone. The upper complex consists of a nappe-like structure, where a major top to the east compressional shear is recorded. The lower tectonic complex consists of an ophiolite-bearing sequence showing typical high- P/low- T parageneses (Mg-carpholite and Na-amphibole). The 40Ar/39Ar geochronology on phengites in equilibrium with blueschist minerals provided a minimum age estimate for the blueschist event in the lower complex rocks at the Oligocene-Eocene boundary (around 35 Ma). Ductile to brittle top to the west extensional shear accompanied the nearly isothermal retrogression and exhumation of the lower complex rocks, reworking the previous nappe contacts with shear localization along the upper/lower tectonic complex discontinuity. The 40Ar/39Ar dating indicates that this postnappe stacking tectonic evolution took place from 30 Ma onward. It is proposed that exhumation of the deep-seated rocks occurred below a top to the west extensional detachment active during convergence and orogenic complex formation (synorogenic extension). The age of this detachment is bracketed between 30 Ma and the post-orogenic Neogene basin sedimentation (middle-upper Miocene). The revised structural and metamorphic scenario is here integrated into a new tectonic evolutionary reconstruction, which involves an early high- P/low- T top to the east crustal thickening episode during the construction of the Apennine orogenic wedge (Eocene-Oligocene), followed and overprinted by a top to the west extensional shear, probably active from the late Oligocene. [ABSTRACT FROM AUTHOR]

In the Central Mediterranean two back-arc basins, the Liguro- Provencal (LPb) and the Tyrrhenian basin (Tb), opened progressively and consecutively from the late Eocene--Oligocene to the present. Evolution in space and time of rifting and drifting processes, along three different transects across these basins, shows differences in the style of extension: LPb opened with the formation of a narrow, single rift, while in the Tb deformation and magmatism is spread over a wide area.Moreover at the Northern end of the Tb the locus of extension progressively migrated towards the east whereas in the Southern Tb the locus of extension and magmatism migrated inside the basin, inducing continental break-up and drifting of the previously formed older conjugate basins. We propose that these different styles of back-arc extension depend upon internal conditions, such as prerift rheology linked with its geological heritage, and external conditions, e.g. the style of subduction. [ABSTRACT FROM AUTHOR]