the puglia uplift se italy an anomaly in the foreland of the apenninic subduction due to buckling of a thick continental lithosphere the apenninic foreland shows two distinct structural signatures comparing the central adriatic sea and the puglia region during the pliocene pleistocene the central adriatic underwent high subsidence rates due to the eastward rollback of the hinge of the west dipping apenninic subduction the puglia region and the bradanic foredeep are located southward along strike in the same foreland but in contrast with the central adriatic after pliocene early pleistocene subsidence they underwent uplift since the middle pleistocene the geometry and the kinematics of the frontal accretionary wedge and related foreland changed from that moment on between the two areas at the front of the central northern apennines off scraping and subsidence continued whereas the foredeep and foreland of the southern apennines were buckled those differences are interpreted as being due to the larger subduction hinge rollback rate since middle pleistocene of the central adriatic lithosphere 70 km thick with respect to the thicker puglia 110 km the different thicknesses of the continental crust and lithosphere were inherited from the mesozoic rifting that disrupted the adriatic plate the different thicknesses appear to have controlled the variable degree of flexure of the lithosphere and its asthenospheric penetration rate the tremiti e w alignment is the right lateral lithospheric transfer zone of those different tectonic regimes the consequent different dip of the subduction in the two sections steeper west of puglia could also explain the lower elevation of the southern apennines compared to their central northern sector

segmentation and configuration of subducted lithosphere in italy an important control on thrust belt and foredeep basin evolution the apennine foredeep basin system located on continental crust consists of four roughly parallel basin segments each containing a flexural outer rise and an inner trough that deepens continuously toward the thrust belt flexural modeling of subsidence data across the basin indicates that this foredeep basin results mainly from deep subsurface loads acting on the subducted slab from within the subduction zone rather than from the topographic load of the apennine mountains the geometry of the four basin segments observed within the apennine foredeep is thus inferred to reflect subduction of segmented lithosphere where each lithospheric segment corresponds to a segment of the foredeep basin beneath the basin and in the foreland the lithosphere is continuous segmentation occurs only at depth beneath the thrust belt this pattern olf segmentation of the subducted lithosphere at depth is reflected in the large scale geometry of the outer part of the apennine thrust belt and appears to control it similarly the pattern of segmentation also appears to control the position of the eastern limit of back arc type extension in western italy these relations strongly suggest a genetic relation between subduction zone processes foredeep basin geometry and thrust belt evolution in which the configuration of the subducted lithosphere largely controls the large scale surface deformation observed in the apennine system

a geodynamic model of the southern apennines accretionary prism the apennines comprise a neogen quaternary accretionary prism that shows several anomalies with respect to classic alpine type mountain belts namely i low elevation ii a shallow new moho below the core of the belt iii high heat flow in the internal parts iv mainly sedimentary cover involved in the prism v a deep foredeep and vi a fully developed back arc basin the suction exerted by a relatively eastward migrating mantle can determine the eastward retreat of the subduction zone and an asthenospheric wedging at the retreating subduction hinge heat flow geochemical and seismological data support the presence of a hot mantle wedge underlying the western side of the apenninic accretionary prism a thermal model of the belt with foreland dipping isotherms fits with deepening of the seismicity toward the east mantle volatiles signatures are also widespread in springs along the apennines

andalusite sillimanite quartz veins as indicators of low pressure high temperature deformation during late stage unroofing of a metamorphic core complex turkey ductilely deformed veins consisting of quartz andalusite in which the andalusite is partially replaced by fibrous sillimanite locally occur in garnet sillimanite schist near a margin of the nigde metamorphic core complex in south central turkey mineral assemblages reaction textures and structural features of the veins record low pressure high temperature deformation during exhumation of mid crustal rocks the partial replacement of andalusite by sillimanite may indicate a late stage increase in temperature and or fluid pressure possibly related to miocene magmatism during extensional unroofing of the core complex aluminosilicate bearing veins are observed at the eastern margin of the massif where metapelitic rocks were deformed during unroofing of the core complex veins formed in aluminous rocks where deformation enhanced permeability allowed fluid flow during extensional shear the cm scale veins are typically boudinaged and form asymmetric lenses concordant with the host rock foliation and are parallel to the down dip lineation defined by sillimanite and stretched biotite aluminosilicate bearing boudins record top to the east shear sense which is compatible with the extensional shear sense displayed by structures in the host rock

overriding plate deformation and variability of fore arc deformation during subduction insight from geodynamic models and application to the calabria subduction zone in nature subducting slabs and overriding plate segments bordering subduction zones are generally embedded within larger plates such large plates can impose far field boundary conditions that influence the style of subduction and overriding plate deformation here we present dynamic laboratory models of progressive subduction in three dimensional space in which the far field boundary conditions at the trailing edges of the subducting plate sp and overriding plate op are varied four configurations are presented free both plates free sp fixed op fixed and sp op fixed we investigate their impact on the kinematics and dynamics of subduction particularly focusing on overriding plate deformation the results indicate that the variation in far field boundary conditions has an influence on the slab geometry subduction partitioning and trench migration partitioning our models also indicate that in natural narrow subduction zones assuming a homogeneous overriding plate the formation of back arc basins e g tyrrhenian sea aegean sea and scotia sea is generally expected to occur at a comparable location 250 700 km from the trench irrespective of the boundary condition in addition our models indicate that the style of fore arc deformation shortening or extension is influenced by the mobility of the overriding plate through controlling the force normal to the subduction zone interface trench suction our geodynamic model that uses the sp op fixed setup is comparable to the calabria subduction zone with respect to subduction kinematics slab geometry trench curvature and accretionary configuration furthermore the model can explain back arc and fore arc extension at the calabria subduction zone since the latest middle miocene as a consequence of subduction of the narrow calabrian slab and the immobility of the subducting african plate and overriding eurasian plate this setting induced strong trench suction driving fore arc extension and forced subduction to be accommodated almost entirely by slab rollback not trenchward subducting plate motion while trench retreat was accommodated almost entirely by back arc and fore arc extension not trenchward overriding plate motion comparable to our sp op fixed model

pliocene quaternary transpressional evolution of the anzi calvello and northern s arcangelo basins basilicata southern apennines italy as a consequence of deep seated fault reactivation abstract in this paper we report the results of a study of the plio pleistocene anzi calvello basin and the northern sector of the s arcangelo basin southern apennines italy our work suggests that the evolution of the anzi calvello basin is related to the activity of a deep seated roughly nne trending dextral transpressional fault zone camastra transcurrent fault zone ctfz structural control of sedimentation by this structure is indicated by the geometry of the unconformity bounded stratigraphic units as well as by the deformation of the basin fill en echelon n s trending thrusts n to ne trending dextral transpressional faults and nw to nnw striking folds affecting the substratum constitute the surface response to lateral displacement along the ctfz the s arcangelo basin is bounded to the north by a deep seated roughly wnw nw trending sinistral transpressional structure valsinni lateral ramp vlr that terminates northwestward against the ctfz at the surface the vlr is dominated by back thrusts and by transpressional fault zones the vlr has been interpreted as the sinistral lateral ramp of the large scale valsinni thrust anticline and it is inferred to have strongly controlled local deposition within the s arcangelo basin the deep seated structures ctfz and vlr probably represent reactivated pre existing normal and transfer faults affecting the rigid apulian platform that were generated during passive margin evolution as well as during the flexural bending of the apulian lithosphere during the pliocene pleistocene these structures were reactivated as lateral ramps accommodating the thrusting within the apulian platform transpression along the lateral ramps in the apulian platform propagated upwards through the nappe pile giving rise to a complex surface structural pattern and the local development of flower like structures

shear velocity structure of the tyrrhenian sea tectonics volcanism and mantle de hydration of a back arc basin the tyrrhenian sea in the mediterranean formed as the result of roll back of the adriatic and ionian subducting plates it is mostly underlain by strongly thinned continental lithosphere but contains two small oceanic basins in the southern tyrrhenian the youngest one located just behind the active magmatic arc its regional setting with dense station coverage provides a unique opportunity to derive a high resolution 3 d shear velocity model of this back arc basin and surrounding onshore areas using interstation rayleigh wave dispersion measurements our tomographic model extending to a depth of approximately 160 km displays a pronounced nearly ring shaped low shear velocity zone between 70 and 110 km depth which surrounds the older oceanic vavilov basin the sharp velocity decrease at 70 km depth can be explained by the transition from a relatively dry lithospheric mantle to more hydrous asthenospheric mantle material the tectonic evolution of the region and the correlation of the low velocity anomaly with subduction related volcanism indicate that the low velocity anomaly reflects hydrous mantle material in present or former mantle wedge regions we suggest that the absence of the low velocity zone beneath the vavilov basin is due to mantle dehydration caused by the creation of morb crust whereas temperature effects may dominate the asthenospheric shear velocity differences between various back arc basins we find that the variations in shear velocity structure within the tyrrhenian area are best explained by variations in mantle water content

oppositely directed pairs of propagating rifts in back arc basins double saloon door seafloor spreading during subduction rollback 1 when a continent breaks up into two plates which then separate from each other about a rotation pole it can be shown that if initial movement is taken up by lithospheric extension asthenospheric breakthrough and oceanic accretion propagate toward the pole of rotation such a propagating rift model is then applied to an embryonic centrally located rift which evolves into two rifts propagating in opposite directions the resultant rhombic shape of the modeled basin initially underlain entirely by thinned continental crust is very similar to the oligocene to burdigalian back arc evolution of the valencia trough and the liguro provencal basin in the western mediterranean existing well and seismic stratigraphic data confirm that a rift did initiate in the gulf of lion and propagated southwest into the valencia trough similarly seismic refraction gravity and heat flow data demonstrate that maximum extension within the valencia trough liguro provencal basin occurred in an axial position close to the north balearic fracture zone the same model of oppositely propagating rifts when applied to the burdigalian langhian episode of back arc oceanic accretion within the liguro provencal and algerian basins predicts a number of features which are borne out by existing geological and geophysical particularly magnetic data these include the orientation of subparallel magnetic anomalies presumed to be seafloor spreading isochrons in both basins concave to the west fracture zones southwest of the north balearic fracture zone and concave to the east fracture zones to its northeast a spherical triangular area of nw oriented seafloor spreading isochrons southwest of sardinia the greater nw extension of the central youngest magnetic anomaly within this triangular area in agreement with the model predicted northwestward propagation of a rift in this zone successively more central younger magnetic anomalies abutting thinned continental crust nearer to the pole of rotation in the liguro provencal basin the latter feature demonstrates that a rift also propagated northeast in the liguro provencal basin at least in its oceanic accretion phase of development an adaptation of an existing model for subduction slab detachment occurring along the north african margin in the late burdigalian langhian proposes propagation in opposite directions of the slab tear the resultant rhombic slab detachment is closely associated in space and time with the rhombic form of the algerian liguro provencal basins suggesting a cause and effect relationship

neogene quaternary tectonic evolution of the southern apennines 1 in this paper we present a study of a segment of the southern apennine mountain belt which extends from the pollino mountain range to the south and the sele valley to the north combining regional data and structural information with the results based on the interpretation of several seismic reflection lines and many deep well logs three regional cross sections have been constructed the cross sections highlight the overall architecture of the orogenic belt which is constituted by a thin tectonic layer of allochthonous nappes represented by remnants of the neotethyan accretionary wedge e g liguride and sicilide units resting above a thick imbricated thrust belt this latter comprises distinct units represented by platform carbonates western platform monte alpi costamolina and tempa rossa units and pelagic basin domains lagonegro campomaggiore and faeto units deriving from the late tortonian quaternary deformation of the adria paleomargin the restoration of the three cross sections furnished information on the primary geometry of the adria paleomargin which was characterized by the occurrence of a large platform domain dissected by distinct pelagic basins with complex and irregular margins represented by pelagic embayments and platform promontories developed during the mesozoic and the late cretaceous tertiary times the reconstructed geometry of the paleomargin provided moreover useful insights to evaluate the mode of deformation and the rates of shortening of the thrust belt and to explain the neogene stratigraphy of the distinct platform domains the mode of deformation of this portion of the southern apennines was dominated by the occurrence of crustal thrusts located along previous weakness zones represented by the boundaries between platform and pelagic domains these crustal thrusts caused the complete closure of the basin areas and the direct overthrusting of the different buoyant platform domains with contractional rates characterized by values ranging from 3 1 to 4 3 cm yr finally a geodynamic model in which the southern apennine mountain belt is considered the result of lateral extrusion produced by the indentation of the pelagian block and by the consequent opening of the tyrrhenian sea is also proposed

seismic characteristics and identification of negative flower structures positive flower structures and positive structural inversion negative and positive flower structures and positive inverted structures imply specific modes of formation and their distinctive characteristics make them important criteria for the identification of certain structural styles a negative flower structure from the andaman sea consists of a shallow synform bounded by upward spreading strands of a wrench fault that have mostly normal separations paralleling monoclines and oblique en echelon normal faults flank the divergent wrench fault a positive flower structure from the ardmore basin oklahoma consists of a shallow antiform displaced by the upward diverging strands of a wrench fault that have mostly reverse separations en echelon folds are present on either side of this convergent wrench fault flower structures may resemble extensional or contractional fault blocks on individual seismic profiles flower structures are identified by their unique internal fault and fold architecture by their association with a straight and throughgoing zone of deformation and by their lack of a consistent sense of separation or regional upthrown side positive structural inversion at the rambutan oil field south sumatra basin has formed a shallow anticlinorium and has partly uplifted the underlying graben deeper fault segments bounding the graben have retained their normal fault profiles but at shallow levels some of these faults have reverse separations similar changes of separation with depth may be produced by strike slip but sets of faults with listric profiles and nearby blocklike trend patterns identify the inversion as a dip slip event where correlation of reflections is uncertain or deep control is unobtainable positive inverted structures may also resemble contrational fault blocks detached normal fault assemblages and certain negative inverted structures

tectonic model and three dimensional fracture network analysis of monte alpi southern apennines abstract the monte alpi southern italy is well known as an outcropping analogue of the val d agri subsurface units which host a number of oil fields of economic importance this paper presents an example of a detailed study which integrates stratigraphy structural geology tectonic analysis and fracture network study the new structural model presented is based on a detailed 1 12 500 field survey of the area whose results are illustrated in a comprehensive outcrop map geological map and structural cross sections and stereographic projections and palaeostress inversion calculations of a mesostructural data set the monte alpi unit is characterised by a 2000 m thick sequence of jurassic cretaceous platform carbonates conformably covered by middle upper miocene calcarenites this sequence is unconformably covered by upper messinian terrigenous clastics mainly along a number of major growth faults our detailed mapping revealed that the monte alpi unit is tectonically overlain by the lagonegro basinal unit thin siliceous carbonates and remnants of pelagic pelitic and carbonate deposits all highly deformed and by the monte la spina unit cataclastic mesozoic carbonates and dolomites this solves earlier raised questions concerning the palaeogeographic provenance of the carbonates outcropping in the area which can thus without any doubt be correlated with the external carbonate domains known from the subsurface the present day structure shows a structural inversion along the major late miocene growth faults which acted as sinistral transpressive faults the latter faults are part of a regional set dissecting the southern apennines active up till at least middle pleistocene times a fracture study was performed on the mesozoic carbonates of the area in order to collect data regarding length distribution orientation density and spatial heterogeneity of the fracture network to be used for considerations regarding exploration and development of the val d agri reservoirs the data were collected on 37 horizontal strata parallel and vertical outcrop surfaces through photographic restitution and digitising of fracture lineament traces and measurements of orientations of all visible fractures furthermore three major outcropping rock walls along the flanks of monte alpi and santa croce were photographed and fracture and fault zone lineaments were digitised all data were inserted and calibrated in a three dimensional 3d geographic information systems and computer aided design giscad environment consisting of a database and a 3d geographical framework comprising topographic map digital terrain model dtm geological map aerial photograph lineament map and a 3d reconstruction of major fault surfaces making use of the potential of the 3d working environment outcrop surfaces and rock walls were reconstructed at their correct 3d position and orientation data analysis comprised stereographic contour diagrams and rosette diagrams of 1800 fracture orientations in order to recognise main fracture sets three corrections were performed on these data length weighting terzaghi correction removal of sample orientation bias and tilt removal from a comparison between orientation data on various scales combined with field evidence it can be deduced that fault and fracture sets are part of the same structural pattern and that fracture sets were generated prior to plio pleistocene tectonics and passively rotated fracture and fault length distribution was analysed by the generation of diagrams which plot cumulative frequency versus length in log log space normalising for area of observation these diagrams composed of about 30 000 measurements and constituting the most complete data set presented in the literature up till now show that small scale and large scale features form part of one scale invariant system with fractal properties no scale gap is present in our data set which comprises rock wall data in the subseismic scale range it appears that the 3d fracture network can best be described by a fractal dimension of 2 98 and a coefficient of 0 25 the outcome of the study places important constraints on fracture network simulation exercises in hydrocarbon reservoir simulation studies which use numerical input parameters in order to make predictions of the tectonic texture present in the subsurface

growth processes and melange formation in the southern apennines accretionary wedge abstract the southern apennines owe their present geometry to the subduction of an apulian continental lithospheric slab and are thus best interpreted as an accretionary wedge southward the apenninic thrust front branches on to the still active ionian wedge which is related to the present calabro sicilian subduction the interpretation of conventional seismic reflection profiles and exploration wells combined with geologic field studies biostratigraphy and structural geology provide constraints for a geodynamic model for the post messinian growth of the apenninic prism our model for the apennines is a good analogy for submerged oceanic accretionary prisms in both instances features such as out of sequence thrusts underplating and duplexes are viewed as processes to explain the thickening of accretionary wedges syntectonic terrigenous deposits have accumulated in the synclines developed above the flats of pliocene thrust faults these depocenters represent piggy back basins younger accretion at the eastern border of the accretionary wedge has led to a progressive uplifting and tilting of the already emplaced thrust sheets including a continous westward migration of the depocenters in the piggy back basins during pliocene and early quaternary times a contrary west to east migration of the depocenters locally occurred where preexisting flats of pliocene thrust faults have been refolded rather than only being rotated dewatering processes and effects of overpressures on undercompacted sediment deformations can also be studied in the southern apennines melanges and broken formations form an important component of the trench apparently restricted to the base of tectonic nappes listric normal faults are a major structural element which preserves in combination with the erosion of topographic highs and resedimentation in the piggy back basins a uniform geometric shape critical taper for the prism the age and location of these distensive or gravitational effects are also discussed

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

the evolution of the calabrian arc evidence from paleomagnetic and gps observations abstract the present day arcuate shape of the calabrian arc has been accomplished during neogene and early pleistocene by large and opposite vertical axis rotations along the two arms of the arc clockwise cw rotations have been systematically registered in sicily and calabria whereas counterclockwise ccw rotations were measured in southern apennines such opposite vertical axis rotations ceased in the uppermost part of the lower pleistocene about 1 ma ago along almost the entire calabrian arc and are not observed in the present day gps velocity field the end of the calabrian arc bending during the quaternary marks a decrease in the efficiency of the tectonic processes related to the long lived subduction of the ionian slab which caused the halting of the back arc opening in the southern tyrrhenian sea

a proposal for the kinematic modelling of w dipping subductions possible applications to the tyrrhenian apennines system in w dipping subduction zones there is a general eastward progression of the back arc basin accretionary wedge foredeep complex with the forward progression early stages of the complex are revealed by slices of upper crust and sedimentary cover abandoned to the west left floating above a new section of mantle a major shear zone should form at the new moho separating upper crust slices of earlier accretionary stages and the eastward flowing mantle the mantle wedging at the top of the subduction plane could be responsible for the uplift of the central parts of the belt the retreating of the subduction hinge is interpreted as due to the push generated by the eastward mantle flow detected in the hot spot reference frame the foredeep depth is mainly a function of the radius of curvature of the subduction hinge the frontal wedge is constructed from the stacking of the upper layers of the subducting plate and the syntectonic clastics that fill the foredeep which are progressively involved in thrusting and later by extension in order to preserve volume balance the lithosphere of the eastern plate before subduction has to be the same size as that which has been subducted due to the longer length of the arc with respect to the original length of the linear margin between the two converging plates laterally stretched subducted lithosphere is predicted at depth w dipping subductions usually have a short life probably due to their inherent capability to produce new lateral heterogeneities of the lithosphere the thin back arc which are a key factor in controlling and generating new subductions both e and w dipping this model is applied to the apennines tyrrhenian sea system

deformed pleistocene marine terraces along the ionian sea margin of southern italy unveiling blind fault related folds contribution to coastal uplift 1 morphotectonic analysis and fault numeric modeling of uplifted marine terraces along the ionian sea coast of the southern apennines allowed us to place quantitative constraints on middle pleistocene holocene deformation ten terrace orders uplifted to as much as 660 m were mapped along 80 km of the taranto gulf coastline the shorelines document both a regional and a local fault induced contribution to uplift the intermingling between the two deformation sources is attested by three 10 km scale undulations superimposed on a 100 km scale northeastward tilt the undulations spatially coincide with the trace of nw se striking transpressional faults that affected the coastal range during the early pleistocene to test whether fault activity continued to the present we modeled the differential uplift of marine terraces as progressive elastic displacement above blind oblique thrust ramps seated beneath the coast through an iterative and mathematically based procedure we defined the best geometric and kinematic fault parameters as well as the number and position of fault segments fault numerical models predict two fault propagation folds cored by blind thrusts with slip rates ranging from 0 5 to 0 7 mm yr and capable of generating an earthquake with a maximum moment magnitude of 5 9 6 3 notably we find that the locus of predominant activity has repeatedly shifted between the two fault systems during time and that slip rates on each fault have temporally changed it is not clear if the active deformation is seismogenic or dominated by aseismic creep however the modeled faults are embedded in an offshore transpressional belt that may have sourced historical earthquakes

structural evolution of the lucanian apennines southern italy abstract in this paper we present a study of an entire segment of the southern apennines of italy extending from the pollino mountain range to the south to the agri valley to the north in which all the units of the chain are represented combining regional information with detailed structural data obtained from the different tectonic units forming the orogenic belt the structure as well as the tectonic evolution of this portion of the orogenic belt are proposed the overall architecture of this segment of the southern apennines mountain chain represents the result of a complete orogenic cycle in which oceanic subduction syn collisional and post collisional events are well recorded structurally this segment of the orogenic belt exhibits two distinct structural levels separated by a major detachment surface the sole thrust of the accretionary wedge that occur at the surface in the allochthonous nappes and at depth in the adria continental margin the upper level is characterized by an imbricated fan system affecting the allochthonous terranes emplaced during oceanic subduction and the first stages of continent continent collision the lower level is represented by a duplex geometry that has developed in the post collisional stage during evolution of the foreland migrating thrust system involving the carbonate platform basin system of the adria block during the last stages of the mountain building process when the foreland thrust migration was locked by the thickening of the colliding continental crusts the southern apennines were thus affected by a severe strike slip tectonics that dissects the entire mountain belt deeply modifying the previous thrust geometry

tertiary geodynamic evolution of the southern adria microplate the southern adria microplate is the common foreland for the hellenide and southern apennine thrust belts the apulian platform dominates the microplate outcrop well and seismic data allow us to trace the carbonate platform edge whilst structural analysis geophysical and palaeomagnetic data provide important clues to the geodynamic evolution of the region the present structural fabric of apulia is dominated by several e w lineaments that divide the region into different blocks rospo plateau gargano promontory murge ridge salento peninsula apulian plateau one such lineament the pescara dubrovnik line a prominent feature traversing the adriatic sea between central italy and southern croatia has been active since the early mesozoic when it acted as a major transform fault controlling sedimentation along the northern margin of southern adria during the cenozoic the pescara dubrovnik underwent predominantly vertical and oblique movement due to a differential flexural response of the platform and the adjacent pelagic sequences to the thrust belt loading in tertiary time the southern adria microplate was partly involved in heilenide collision the apulian platform can be considered as an area of thicker crust more resistant to underthrusting than the surrounding basins during the orogenic events it acted as a passive rigid indentor causing local distortion of the most external hellenide structures the dextral transpressive activity recorded along the south east margin of this indentor kephallinia line can be interpreted as the result of the oblique collision between the margin of the thick apulian platform in this zone nne ssw striking and the nw se striking hellenic thrust belt horizontal stress generated during the collision was partly transmitted to the rigid foreland re activating palaeo e w faults within the south adria microplate in a dextral strike slip sense the clockwise rotation recorded in the salento peninsula can be explained by the rotation of several nw se striking faulted blocks the rotation was accompanied by the opening of small transtensional basins between blocks this block rotation was caused by the dextral shear that is expressed along the north and the south salento fault zones

nonlinear p wave tomography of subducted lithosphere beneath central southern apennines italy we present new tomographic images for the p wave velocity structure in the upper mantle beneath central southern apennines down to 510 km depth the model is computed by nonlinear inversion of relative arrival times of both direct and secondary teleseismic phases handpicked from over 2800 waveforms recorded by the italian seismic network during 1988 2000 beneath central apennines the images reveal a continuous sw dipping high velocity body from 150 km down to 500 km at shallower depths a pronounced low velocity zone is recognized from the uppermost mantle beneath the apenninic belt down to 200 km below the tyrrhenian area this feature is proposed to affect the seismic structure of the downgoing slab weakening its velocity signature beneath southern apennines high velocity anomalies are reconstructed in the uppermost mantle of the apulian foreland and below the belt in the range 100 400 km low velocity regions interpreted as due to asthenospheric upwelling are recovered above or across the fast structures as at the southeastern end of the apennines where a possible complete slab breakoff is suggested

tectono stratigraphic and kinematic evolution of the southern apennines calabria peloritani terrane system italy abstract temporal controls such as sedimentation ages in foredeep and wedge top basins combined with information about stratigraphic and metamorphic evolution ages and characterization of magmatic rocks deep structures burial and exhumation histories allowed us to obtain kinematic estimations of the southern apennines calabria peloritani terrane system evolution from the late oligocene to recent calculated thrust front velocities suggest to subdivide the orogenic evolution in main five kinematic stages characterized by different velocity trends nine kinematic complexes from a to i i e sets of tectonic units deformed in the same time range are determined according to foredeep ages these complexes bounded by main regional thrust faults encompass one or more tectonic sub units and successions of different paleoenvironment domains paleogeographic evolution model indicates according to available paleomagnetic data a counterclockwise rotation with a mean angle of 60 for the apennine platform carbonates whereas a mean angle of 20 for the eastern sector of the apennine platform and western side of apulian platform shortening estimations for the apennine successions show values ranging between 55 and 88 and a linear best fit indicating an increase from 60 nw sector to ca 90 se sector such high values are consistent with a deformation dominated by a thin skinned tectonics on the contrary the low value of 28 calculated for mt alpi suggests an exhumation ruled by high angle deep seated structures characterized by limited displacements tectonic vergences referred to middle late miocene late miocene and pliocene middle pleistocene when restored indicate an average eastward tectonic transport finally tectonic evolution is summarized in eleven schematic cross sections and corresponding paleogeographic maps

tectonic evolution of arcuate mountain belts on top of a retreating subduction slab the example of the calabrian arc 1 in this paper new paleomagnetic results from the calabrian arc are presented together with a critical review of all paleomagnetic data collected in the last decades in southern italy our study is focused on the upper miocene to middle pleistocene deposits of the crati extensional basin a sector of the arc where an abrupt change in the sense of paleomagnetic rotations is observed paleomagnetic data indicate that the crati basin underwent a uniform clockwise cw rotation of about 15 20 in its central and southern part whereas the northern sector is organized in small scale fault bounded blocks which rotated independently we interpret this pattern of deformation as the evidence of the complex nature of this area which represents the boundary between two domains characterized by opposite rotations the southern apennines which rotated counterclockwise and the calabria and sicily which rotated cw integrating these new paleomagnetic data with paleomagnetic data from southern italy we reconstruct the history of paleomagnetic rotations through time paleomagnetic rotations highlight the peculiarity of the formation of the calabrian arc curvature and imply that either an oroclinal bending model or a progressive arc model cannot be simply applied to the calabrian arc formation we describe a realistic tectonic geodynamic model where the progressive curvature of the calabrian arc is framed within the space time evolution of the ionian subduction system

neogene to quaternary tectonics and mud diapirism in the gulf of squillace crotone spartivento basin calabrian arc italy abstract the calabrian arc is an arcuate tectonic feature formed during the neogene and pleistocene as a consequence of the progressive retreat of the ionian subduction system it is a key area for understanding the geodynamic evolution of the mediterranean sea the aim of this paper is to investigate the sedimentary dynamics and the possibly active deformation in the gulf of squillace and to highlight their relationships with the fluid escape pathways and mud mobilization the squillace embayment is a marine area belonging to the forearc basin of the calabrian arc at the seaward prosecution of the catanzaro depression by interpreting public seismic profiles at different resolutions calibrated by well logs for hydrocarbon exploration it was possible to define the structural setting and the neogene and quaternary stratigraphic architecture the geologic setting of the gulf of squillace shows the occurrence of normal fault systems cutting through both neogene and quaternary deposits during the messinian trans tensional tectonics led to the formation of a basin whose sediments reached the major thickness in the central portion of the embayment since the early pliocene extensional tectonics was dominant and the basin depocenter progressively changed its orientation creating a narrow basin roughly oriented nw se similar tectonic setting was also present during the pleistocene extension a middle to late pliocene contractional event led to development of a thrust zone in the northern crotone swell mud diapirs that occur in the external area of the gulf of squillace are located close to the pliocene and pleistocene depocenter the overpressure provided by the pliocene and pleistocene sediment accumulation on messinian and pre messinian sediments and the evolution of normal fault systems triggered the mud diapirs formation that progressively developed toward the upper slope extensional deformation and mud diapirism influence the morphologic evolution of the slope and the basin resulting in the retrogressive erosion of canyon heads and gravity driven slope failures

active fragmentation of adria the north african promontory central mediterranean orogen global positioning system gps velocities indicate that adria no longer behaves as a rigid tectonic indenter into southern europe and is divided into northwestern and southeastern velocity domains differential motions are recognized in a velocity field determined from the peri tyrrhenian geodetic array ptga and international gps service igs sites in the circum tyrrhenian region of the central mediterranean and published gps velocities from the eastern adriatic coast in a fixed eurasian reference frame ptga and igs site velocities in sicily and southern italy are as much as 10 mm yr in a northward direction similar to gps velocities along the eastern coast of the adriatic sea in contrast velocities in northern italy are small or statistically insignificant and similar to velocities in sardinia and corsica outboard of western adria the tectonic boundary dividing adria is seismically active and passes around the southern and eastern margins of the tyrrhenian basin crosses central italy extends into the adriatic sea and follows the western margin of the dinaride tectonic belt north to the gulf of venice the eastern margin of adria is approximately located and follows the axis of the central dinaric alps southeast to the hellenic arc southeastern adria has a velocity related to northward motion of africa whereas northwestern adria has negligible differential motion in the eurasian frame and now is part of the alpine collage of southern europe

lithosphere tearing at step faults response to edges of subduction zones abstract slab edges are a relatively common feature in plate tectonics two prominent examples are the northern end of the tonga subduction zone and the southern end of the new hebrides subduction zone near such horizontal terminations of subduction trenches ongoing tearing of oceanic lithosphere is a geometric consequence we refer to such kinks in the plate boundary as a subduction transform edge propagator or step other steps are the north and south ends of the lesser antilles trench the north end of the south sandwich trench the south end of the vrancea trench and both ends of the calabria trench volcanism near steps is distinct from typical arc volcanism in some cases slab edges appear to coincide with mantle plumes using 3d mechanical models we establish that step faults are stable plate tectonic features in most circumstances in the probably rare cases that the resistance to fault propagation is high slab break off will occur relative motion along the transform segment of the plate boundary often is non uniform and the step is not a transform plate boundary in the rigid plate tectonics sense of the phrase step propagation may result in substantial deformation rotation topography and sedimentary basins with a very specific time space evolution surface velocities are substantially affected by nearby steps

pliocene quaternary orogenic systems in central mediterranean the apulia southern apennines tyrrhenian sea example in the central mediterranean the africa eurasia convergence led to the development of complex orogenic systems and backarc basins throughout pliocene quaternary times the southern apennines accretionary prism migrated towards the apulia foreland and contemporaneously the tyrrhenian sea backarc basin opened in this study we investigated the offshore of the southern apulia foreland and the southern apennines using seismic reflection profiles and well data in a dedicated gis software we made a detailed stratigraphic analysis reconstructed the structural pattern and built 2d geological models of the main geological surfaces the structure of the apulia region formed during two main tectonic stages lower pleistocene complex extensional faulting developed in a transtensional regime and middle upper pleistocene transpression shortening the southern apennines accretionary prism developed through the pliocene early lower pleistocene and was overprinted by late lower pleistocene middle pleistocene nw se sinistral faults through linking new data from the accretionary prism and the foreland with previous information from the tyrrhenian sea back arc we provide an original interpretation for the relationships between the various provinces that make the central mediterranean crustal puzzle and reconstruct the main phases of the evolution of its pliocene quaternary orogenic cycle we recognized collisional stages of uncoupled plates followed by late lower middle pleistocene post collisional stages of coupled continental plates this pleistocene plates re organization of central mediterranean was probably due to the rupture of the apulia ionian slab or to nnw intraplate shortening transmitted from africa

kinematic role of transverse structures in continental extension an example from the las vegas valley shear zone nevada analysis of the slip budget of the las vegas valley shear zone southern nevada leads to a model that explains many of the kinematic complexities that characterize transverse structures in continental extensional settings including 1 abrupt terminations of these structures along strike 2 large lateral translations across relatively short faults 3 apparent lack of strike slip offset or contradictory evidence of shear sense along some transverse structures 4 significant variation in slip magnitude along strike and 5 juxtaposition of differentially extended terranes on opposite sides of faults many major transverse structures may function largely as transfer faults that either link or form passive boundaries between differentially extended terranes

neogene and quaternary rollback evolution of the tyrrhenian sea the apennines and the sicilian maghrebides reconstruction of the evolution of the tyrrhenian sea shows that the major stage of rifting associated with the opening of this basin began at similar to10 ma it involved two episodes of back arc extension which were induced by the rollback of a west dipping subducting slab the first period of extension 10 6 ma was prominent in the northern tyrrhenian sea and in the western part of the southern tyrrhenian sea the second period of extension mainly affected the southern tyrrhenian sea began in the latest messinian 6 5 ma and has been accompanied by subduction rollback at rates of 60 100 km myr 1 slab reconstruction combined with paleomagnetic and paleogeographic constraints indicates that in the central apennines the latest messinian 6 5 ma arrival of a carbonate platform at the subduction zone impeded subduction and initiated a slab tear and major strike slip faults these processes resulted in the formation of a narrow subducting slab beneath the ionian sea that has undergone faster subduction rollback and induced extreme rates of back arc extension

deep structure of the campanian lucanian arc southern apennine italy abstract recent exploration activities and successful discovery of large oil fields in the upper val d agri area southern apennine italy have encouraged the collection of large quantities of geological and geophysical data and their integration into comprehensive geological models here we present a series of structural profiles based on several hundred kilometres of seismic lines two and three dimensional and the results of many deep wells the best seismic lines have been extensively reprocessed and also tied to magnetotelluric data geological interpretations of those lines have been interactively tested and verified by gravity and magnetic modelling and structural balancing the wells and seismic data demonstrate that the fundamental tracts of the deep architecture of the orogen as it appears today were developed only at the end of the late pliocene the final closure of the ensialic shear zone responsible for the subduction of at least 150 km of continental lithosphere originally underlying the lagonegro basin can be dated as early pliocene the involvement of the inner apulian platform in the core of the belt and the activation of a new and more external left lateral oblique ensialic shear zone can be constrained to the late pliocene pleistocene the seismic profiles clearly show the underthrusting of the outer apulian platform unit beneath the inner apulian platform unit the thick skinned character of the plio pleistocene contractional structures is evident from the structural profiles this geometry is constrained by gravity magnetic data and structural considerations according to the relatively steep angle of dip about 10 of the apulian foreland beneath the chain the structural profiles depict the general architecture of the campanian lucanian arc the apennine platform and lagonegro unit are largely allochthonous and a part of the lagonegro basement could be buried below the apennine platform sole thrust the neogene plastic successions of the apennine platform and lagonegro basin were detached and now outcrop in the bradanic foredeep the inner apulian platform constitutes a huge thrust sheet structured as a wide antiform in the core of the belt its regional culmination roughly corresponds to the val d agri area extensional and transtensional structures cross cut the pre existing compressional structures as shown by the quaternary valleys of vallo di diano and val d agri the profiles shown also highlight the existing contrast between the deep structures in the core of the belt and the tectonic style of the lagonegro liguride and sicilide units these units were in fact subjected to brittle ductile deformation under metamorphic part of liguridi units and deep diagenetic to anchizonal conditions lagonegro units and were affected by a general overthrust shear directed towards the ne the inner apulian platform was on the contrary involved in the thrust belt together with its basement whereas the outer apulian platform affected by a subduction underwent a regional bending with associated normal faulting

high resolution bathymetry and acoustic geophysical data from santa maria di leuca cold water coral province northern ionian sea apulian continental slope abstract a total of 800 km 2 of multibeam echo sounder coverage roughly 800 km of chirp sonar data and 18 km of side scan sonar profiles 100 500 khz were acquired a few km offshore santa maria di leuca south eastern italy from 200 m to 1300 m water depth the explored area belongs to the upper slope of the gently south eastward dipping apulian continental margin northern ionian sea acoustic datasets were collected by three different oceanographic expeditions where evidence of living cold water coral cwc colonies were documented by previous surveys and samples high resolution multibeam bathymetry indicated an extensive rough seafloor with an irregular faulted upper surface to the west reflecting large scale tectonic control on the margin and a highly disrupted upper slope formed by prominent downslope mass movements to the north a broad area in the east was influenced by mass transport deposition which resulted in a very complex hummocky seafloor mainly shaped by detached block like features and failure related bedforms i e low scarps downslope lineations and compressional ridges from the shallow seismic stratigraphic data failure events appeared to be multiple and recurrent and chaotic reflectors both buried and exposed at the seafloor affected most of the investigated area drift sedimentation was also recognised along a central large ridge resulting in an interplay between contour currents and downslope turbidity currents the spatial distribution of the cwc reefs was inferred from the acoustic facies interpretation based on video images and ground truthed by sediment samples it appeared that 1 within the investigated area living coral frameworks were located along large topographic highs facing the main flow of the bottom currents where hard and firm substrata and or failure related sediment bedforms occurred 2 cwc mainly settled on clustered and isolated mound like features tens to a few hundreds of metres long and no more than 25 m high and were located between 600 and 900 m water depth within the broad area affected by downslope mass transport deposits such mound like morphologies could thus be interpreted as a result of sediment accreted by coral growth with the consequent sediment trapping on small scale positive seafloor irregularities formed by different types of pleistocene exposed mass transport deposits their burial prevented by bottom currents

a new interpretation of terraces in the taranto gulf the role of extensional faulting abstract the taranto gulf of southern italy provides an excellent case where it is possible to document the importance of normal faults in displacing terraced deposits the study area is located at the front of the southern apennines that is a fold and thrust belt developed following the closure of the mesozoic tethys ocean and the deformation of the adriatic passive margin during tertiary and quaternary times the outer eastern parts of the belt were structured in quaternary i e up to middle pleistocene times the front of the chain is partially sealed by pliocene pleistocene foredeep deposits which represent the infill of the bradanic trough the upper portion of the middle pleistocene succession consists of marine sands and conglomerates that in the previous literature have been arranged in several orders of terraces analysis of aerial photographs and geomorphological mapping has shown the occurrence of prominent geomorphic lineaments which appear to control the local drainage pattern some of these structures coincide with the map trace of normal faults that produce vertical offsets of the marine terrace surfaces in the order of ca 10 m each many of the fault escarpments reduce their elevation and terminate laterally in other cases fault escarpments are laterally continuous and can be traced for up to 3 4 km scarp height is between 2 and 10 m their mean trend ranges from nne ssw to ene wsw and defines an arcuate pattern that mimics the present coastline an accurate geomorphological sedimentological and stratigraphic analysis has been carried out in a selected area of the bradanic trough pisticci transect to investigate in detail the relationships between normal faults and the development of the terraces this analysis allowed us to recognise five facies associations related to the upper and lower beachface and to the neritic clays which represent the substratum of the terraces more importantly we observed that all the terraced deposits in the pisticci transect could be referred to a single sedimentary body displaced by faults the terraced deposits are related to an event of beach progradation of middle pleistocene age which has been documented in other areas of the italian peninsula these results outline an intimate relationship between the arcuate trend of the recognised fault set and the present coastline pattern the development of the normal faults can be related to large scale gravitational processes developed after the general tilting towards the se of the bradanic trough

styles of back arc extension in the central mediterranean 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

the gulf of taranto southern italy seismic stratigraphy and shallow structure abstract interpretation of seismic profiles across the gulf of taranto southern italy allows us to discuss the seismic stratigraphy and to define the shallow geological structure of this complex area of the northern ionian sea the apulian slope is a down faulted passive margin covered by irregular unconsolidated plio quaternary sediments the sedimentary fill rests on presumed discontinuous upper miocene deposits and on mesozoic and cainozoic strata acoustic basement the taranto valley is a thickly sedimented trench like feature that is the submerged extension of the onshore bradanic fore deep the eastern calabrian margin intensively cut by normal faulting comprises a lower acoustic sequence representing the widespread allochtonous apenninic units these units overthrust towards the east the unconsolidated taranto submarine valley sedimentary fill creating a sinuous nw se trending thrust front