a recent tectonic reorganization in the south central mediterranean abstract new geodetic data combined with seismicity geologic and geochemical information document a major tectonic reorganization in the central mediterranean around 0 8 0 5 ma when rapid trench migration and consequent tyrrhenian back arc extension which dominated the region s evolution since the tortonian 10 8 ma essentially stopped in response the african convergence in sicily was transferred to a back thrust in the southern tyrrhenian characterized by frequent m5 6 earthquakes in the last 20 years a diffuse transform boundary formed across northeastern sicily to connect the sicilian and calabrian plate boundaries causing opening of the messina straits home to large historical earthquakes and unusual volcanism in the aeolian island arc and the intraplate mount etna a divergence of the ionian region from the main part of africa with northeastward motions that reflect the joint influence of african push and hellenic slab pull and are transmitted to calabria and adria could explain motions observed in the sicily channel calabria and apulia as well as the high level of southeastern sicilian seismic activity

evolution of the northwestern iblean mountains sicily uplift plicocene pleistocene sea level changes paleoenvironment and volcanism the late miocene to pleistocene evolution of the northwestern iblean plateau sicily is marked by a complex interplay of subaerial and submarine volcanism subsidence and uplift eustatic sea level changes and shallow water carbonate and clay sedimentation volcanic activity occurred in distinct phases differing drastically in volume chemical composition eruptive and depositional sites and eruptive mechanisms six of the newly defined formations in the northwestern iblean plateau are either entirely volcanic or contain significant amounts of volcanics the eastern part of a shallow marine basin was filled completely by late pliocene tholeiitic lava flows militello formation that had advanced subaerially from the south southeast lava deltas advanced southwestward on top of earlier pillow breccia debris flow deposits intertongued with soft trubi marls and chalks true submarine eruptions monte caliella formation simultaneously produced densely packed pillow piles up to 250 m thick inferred water depths based on volcanologic and paleoecologic criteria of interbedded and overlying calcarenites agree well

simulation of collision zone segmentation in the central mediterranean abstract collision processes between the african and european plates in the ionian sea offshore calabria and in sicily take place in several ways to the east normal subduction of oceanic crust underlying the ionian sea occurs underneath the calabrian arc whereas to the west continental collision between the pelagian block and the calabrian arc which extends from calabria to the northeastern tip of sicily and offshore of the island to the north gives rise to the maghrebian thrust belt on mainland sicily this belt consists mostly of stacked basinal and platform carbonates of mesozoic early tertiary age deposited along the africa passive margin no clear subduction characterizes the area north of the hybleandashmalta plateau where it collides with the maghrebian chain the origin of the hybleandashmalta plateau is unclear geophysical data indicate however that its crustal structure is different from that of the surrounding pelagian foreland crustal structure variations at the edge of the subducted african plate may thus cause the observed segmentation of the collisional arc system a computer model of the region was created to learn about the deformation and faulting processes in the region the simulation starts prior to the collision of the pelagian block with the calabrian arc with time the hybleandashmalta plateau collides with the northern crustal block and as a result a new simulated topography a new distribution of velocities and most important a new distribution of fracture zones are created a shear fracture zone is formed east of the hybleandashmalta plateau malta escarpment extending to the subduction zone at the calabrian arc a less active strike slip fracture zone is created west of the hybleandashmalta plateau an additional e w trending active fracture zone is creating in the southern part of the simulated area this feature may correspond to a fault zone which runs from the strait of sicily to the ionian sea

magnetic and structural constraints for the noncylindrical evolution of a continental forebulge hyblea italy 1 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

characterization of the magnetic fabric of rocks abstract an inextensive system of magnetic susceptibility anisotropy factors is suggested which is sufficient in the majority of practical applications for characterizing the magnetic fabric of rocks the system involves three newly devised factors the corrected anisotropy degree the shape factor and the difference shape factor the first of these characterizes the quantity of anisotropy somewhat better than the commonly used anisotropy degree the shape factor characterizes the quality of anisotropy i e the shape of the susceptibility ellipsoid in a convenient way its definition is based on a certain analogy between the anisotropy ellipsoid and the strain ellipsoid the difference shape factor can replace the shape factor when only the differences between the principal susceptibilities are given while the mean susceptibility is unknown

crustal structure variations and transcurrent faulting at the eastern and western margins of the eastern mediterranean abstract crustal structure variations within the crust of the eastern mediterranean as well as within the continental crust of the land areas east and west of the basin have caused segmentation of the collision zones which extend from sicily through the calabrian arc the hellenic arc and the cyprian arc to the taurus chain on both sides of the eastern mediterranean in southeastern sicily and in the levant similar tectonic features have developed hinge faults exist along both continental margins due to the different modes of collision between the land areas and the adjacent oceanic areas landward of the margins two large transcurrent fault systems the scicli fault zone and the dead sea rift have developed due to the existence of unique crustal units within the continental crust adjacent to the margins on both sides these units are more buoyant than the adjacent crust and resist underthrusting the initial faulting along both transcurrent fault systems probably started at the collision zone in the north and propagated to the south where large extensional areas the pantelleria rift and the red sea exist

sedimentary and tectonic evolution of the eastern hyblean plateau southeastern sicily during late cretaceous to quaternary time abstract two palaeogeographic domains have been distinguished in the cretaceous quaternary sequences which crop out in the hyblean region of southeastern sicily in the northeast shallow water algal bryozoan calcarenites of oligocene miocene age overlie either cretaceous rudist limestones or volcanics further to the northeast the stratigraphic gap increases as the miocene limestone thins and in the a g i p well catania 10 plio pleistocene sediments and volcanics directly overlie upper jurassic rocks in the southwestern part of the hyblean plateau pelagic sediments occupy the cretaceous miocene interval they were deposited in a shallow basin dipping gently towards the southwest the transition between the two zones is marked by much evidence of synsedimentary tectonic activity such as widespread slumping and the development of megabreccias composed of cretaceous and eocene blocks the palaeogeographic picture is one of carbonate reefs and volcanic seamounts developing in the upper cretaceous they formed platforms fault bounded to the west and southwest from which were derived the detrital sediments found in the basin and occasional spectacular gravity slides in present day terms the structural high probably corresponds to the northeastern margin of the hyblean plateau and in part to the siracusa syracuse malta escarpment the pattern is little changed in the upper miocene with volcanoclastics of phreatomagmatic origin intercalated with coral bioherms overlying algal bryozoan calcarenites upper tortonian lower messinian limestones with a restricted fauna indicate a shallow water environment which grades up into continental conditions in the eastern hyblean plateau the tertiary sequence is capped by pliocene submarine to subaerial mafic lava flows lower pleistocene sediments consist of biocalcarenites and clays which fill deep graben delimited by plio pleistocene faults the inshore continuation of the malta syracuse escarpment system of faults from a tectonic standpoint the hyblean region a gently deformed segment of the african continental margin acted as a foreland during tertiary times a cretaceous eocene tectonic phase was responsible for the palaeogeographic pattern which existed during most of the cenozoic the present pattern is the result of three main tectonic phases following the regional upper miocene uplift of early middle pliocene plio pleistocene and middle pleistocene recent age which influenced the tectonic evolution of the present ionian coast and the malta syracuse escarpment

3 d deformation pattern analysis and evolution of the anisclo anticline southern pyrenees understanding the genetic relationships of folding related deformation structures is of importance for both academic and industrial purposes we analysed the three dimensional deformation pattern of the anisclo anticline in the southern pyrenees the specifically designed statistical method includes sequential steps of statistical and spatial data analysis and classification our results indicate that pressure solution cleavage frequency exhibits a spatial distribution that depends on the position within the fold conversely such a dependence does not occur in joints and veins consequently our data suggest that pressure solution cleavage is the most appropriate deformation structure for unravelling fault fold kinematics in carbonate multilayer in particular we found that the spacing of solution cleavages s is related to the corresponding bed thickness h this supports the use of h s value for deformation intensity quantification instead of spacing in the anisclo anticline analysis of h s indicates the occurrence of three main deformation panels whose restoration suggests that fold evolution progressed from layer parallel shortening to decollement folding up to thrust breakthrough and fault propagation folding comparison of h s values with finite strain data indicates that line length was not preserved during fold evolution this evidence has important implications for the kinematic interpretation of layer parallel shortening and cross section balancing

the dip of the foreland monocline in the alps and apennines the foreland monocline dips underneath thrust belts and accretionary wedges both in oceanic and continental subduction zones we present new data on the dip of the monocline in the frontal part of two orogens the alps and the apennines there is an overall difference between the dip of the relative monoclines and there is also a strong lateral variation along both arcs in the alps the regional dip varies between 0 in the remote foreland to an average of 2 3 at the front of the thrust belt below the foredeep to about 5 beneath the external thrust sheets within 40 km from the leading edge of the accretionary wedge the regional dip of the monocline in the apennines has an average of 4 5 at the front of the thrust belt below the foredeep to about 10 beneath the external thrust sheets within 40 km from the leading edge of the accretionary wedge there are areas where the dip exceeds 20 the apennines though topographically lower than the alps present higher monocline dips and a deeper foredeep moreover there are variations in the dip of the monocline moving along the strike of the two belts the low values coincide with permian mesozoic inherited horsts whereas the steeper values correspond to basinal areas and they usually match the salients of the thrust belt front within the salients the distance between thrust ramps increases therefore there are two orders of mean values of the dip of the foreland monocline the first at the orogen scale more than 1000 km wavelength the second at the regional scale 100 200 km wavelength within the single orogen lateral variations in the lithospheric buoyancy due to the inherited mesozoic stretching may explain the second order variations in foreland dip but not the first order mean values which seem to be more sensitive to the geographic polarity of the subduction rather than to the lithospheric composition which is rather similar in the alpine and in the central northern apennines slabs

integrated planktonic foraminifera bolboforma and carbon isotope stratigraphy in a mid early late miocene carbonate ramp setting from the acreide area sicily taxa of bolboforma a marine calcareous microfossil group of uncertain origin with affinities to protophytic algae are generally used for biostratigraphy of lower eocene to lower pleistocene marine sediments from high latitudes biostratigraphy based on bolboforma has been applied only rarely to european outcrop sections and very rarely to mediterranean sections three bolboforma and two planktonic foraminifera events are identified and used to interpret the sedimentation rate of the 90 m of slope sediments from the palazzolo section palazzolo acreide area sicily and spanning the interval from 11 9 to approximately 10 5 ma carbon isotope stratigraphy supports the age assigment based on bolboforma and planktonic foraminifera in particular the sediments of the palazzolo section seem to record the latest pulse of the monterey event a major perturbation in the global carbon cycle related to global intensification of upwelling expanded use of the bolboforma may thus improve stratigraphy in outcropping miocene sequences in temperate regions particularly in shallower water facies with poorly resolved planktonic foraminifera and nannofossil stratigraphy

the influence of deformation mechanisms on magnetic fabrics in weakly deformed rocks abstract magnetic fabrics of weakly deformed rocks are not simply correlated with the principal finite strain directions depositional magnetic fabrics persist at 30 shortening where the rocks are deformed by particulate flow grain boundary sliding rocks with a spaced stylolitic cleavage believed to be formed by pressure solution and shortened by 20 50 have maximum susceptibility parallel to the intersection of cleavage and bedding this type of magnetic fabric is attributed to the interference of a depositional magnetic fabric between cleavage surfaces with a tectonic magnetic fabric in the cleavage surfaces

patterns of tectonic stress in sicily from borehole breakout observations and finite element modeling the orientation of in situ tectonic stress was deduced from borehole breakout analysis of 22 wells from onshore sicily the results allow us to distinguish the stress field of different geological units 1 a nearly nnw 148 orientation is detected in the hyblean plateau 2 a nne shmax direction characterizes the gela area to the north within the thrust belt around mount judica the shmax direction swings to ne in the northeastern segment of the foredeep the catania plain the direction of shmax is roughly parallel to the ne trending grabens that mark the northern margin of the hyblean plateau 3 the southwestern segment of the foredeep has no preferential shmax orientation and may act as a transition zone with isotropic horizontal stresses 4 in western sicily a shmax orientation from n s to nw se is observed this fits well the kinematics of the se migrating egadi and adventure thrust belts and the direction of shortening inferred from the modern seismicity of the area a three dimensional finite element modeling including the most important tectonic features was performed modeling results of the stress field indicate that the nnw trending shmax is locally influenced by the variation of crustal thickness and local zones of weakness in addition the pantelleria rift causes a rotation of the regional nw se stress orientation to nne along the northern rim of the rift system including large on shore areas in the adjacent central south sicily

paleomagnetic study of sicily consequences for the deformation of italian and african margins over the last 100 million years abstract paleomagnetic analysis of cenozoic sediments from the iblean platform 12 sites 100 samples has provided four new poles these data are combined with those available from volcanic series to yield a new apparent polar wander path for stable sicily since the upper cretaceous this curve when compared to a revised curve for africa using a selection of available data points demonstrates a 15 rotation of sicily with respect to africa during the plio pleistocene this rotation accounts for the extensional tectonic regime that prevails in the pelagian sea and which is evidenced by en relais rifts malta pantelleria linosa associated with alkaline volcanism of pliocene and quaternary age paleomagnetic directions from various areas of the italian peninsula also indicate anticlockwise rotations with diverse amplitudes the chronology of these rotations is consistent with a deformation of the western italian margin during progressive suturation from north to south of the corsican sardinian block since the end of the oligocene

stress directions and shear wave anisotropy observations from local earthquakes in southeastern sicily italy the spatial distribution of 414 earthquakes 1 0 m l 4 6 recorded from 1994 to 2002 in southeastern sicily italy has been analyzed the seismicity generally coincides with mapped plio quaternary faults including the north north west south southeast striking offshore fault system which is the most important tectonic structure of the area for the best located events we computed 70 focal mechanisms by combining p wave polarities with s wave polarizations a predom inance of strike slip and normal faults was observed focal mechanisms were then inverted for stress tensor parameters by using the algorithm of gephart and forsyth the results highlighted a region governed mainly by a north northwest south south east to northwest southeast compressional stress regime moreover anisotropy anal ysis of shear waves showed a polarization of fast s waves coherently aligned with this stress direction a finer scale analysis of the stress tensor evidenced three regions characterized by slightly differing orientation of the greatest principal stress axis r1 the eastern sector displays a nearly horizontal r1 trending northwest southeast the central sector is affected by a low dip north northwest south southeast r1 whereas in the western sector a north northwest south southeast oriented r1 with a higher dip angle was detected finally the comparison of the spatial distribution of seismicity occurring during 1994 2002 with locations of previous instrumental earthquakes and larger m 5 0 historical events showed that the seismicity patterns are persistent

tectonic analysis of a flexed foreland the ragusa platform abstract detailed field studies of fracture patterns and paleostress reconstructions based on analyses of fault slip data sets allow the identification of the late cenozoic stress pattern evolution of the ragusa platform during the late miocene to early pleistocene period a complex extensional pattern developed it was dominated in almost the entire hyblean plateau by nw se to nnw sse extensions related to the flexure of the foreland under the load of the allochthonous units of the sicilian fold and thrust belt these extensional tectonics were characterized by ne sw to ene wsw trending normal faults and grabens in eastern hyblea ne sw to ene wsw extension have prevailed at least since the late cretaceous they are linked to the effects of the malta escarpment in the western ragusa platform a third minor wnw ese extension associated with sets of nne ssw trending normal faults may be correlated with the development of the gela basin in addition these major extensions induced complex patterns of perpendicular normal fault systems through permutations between the principal stress axes 2 and 3 the pliocene pleistocene extensional paleostress field evolution is marked in almost the entire platform by the alternation of two or three main extensional stress patterns ne sw to nnw sse wnw ese and ne sw to ene wsw extensions each of them controlled by particular boundary conditions three minor compressional paleostress orientations have been identified they correspond to three minor compressional events dominated by 020 030 070 080 and 100 110 compressional directions these events occurred in within the general pliocene pleistocene extensive context the 100 110 event is of early middle pliocene age its large regional distribution suggests that this event may have resulted from interactions between the major blocks constituting the africa eurasian boundary the relative chronology shows that the 020 030 compression predates the 070 080 one the origins of these compressional events are still uncertain due to poor regional control

lithospheric strength variations as a control on new plate boundaries examples from the northern red sea region abstract the complex plate boundary between arabia and africa at the northern end of the red sea includes the gulf of suez rift and the gulf of aqaba dead sea transform geologic evidence indicates that during the earliest phase of rifting the red sea propagated nnw towards the mediterranean sea creating the gulf of suez subsequently the majority of the relative movement between the plates shifted eastward to the dead sea transform we propose that an increase in the strength of the lithosphere across the mediterranean continental margin acted as a barrier to the propagation of the rift a new plate boundary the dead sea transform formed along a zone of minimum strength we present an analysis of lithospheric strength variations across the mediterranean continental margin the main factors controlling these variations are the geotherm crustal thickness and composition and sediment thickness the analysis predicts a characteristic strength profile at continental margins which consists of a marked increase in strength seaward of the hinge zone and a strength minimum landward of the hinge zone this strength profile also favors the creation of thin continental slivers such as the levant west of the dead sea transform and the continental promontory containing socotra island at the mouth of the gulf of aden calculations of strength variations based on changes of crustal thickness geotherm and sediment thickness can be extended to other geologic settings as well they can explain the location of rerifting events at intracratonic basins of backarc basins and of major continental strike slip zones

sedimentology and palaeoenvironment of the southeast sicilian tertiary platform carbonates abstract a thick succession of shelf and shelf slope carbonates is developed in southeastern sicily sedimentological aspects of the oligocene to tortonian sequence including distribution and palaeoenvironmental factors are considered a new formation and four new members are proposed in the upper part of the succession the region comprises a western half typically exhibiting the principal deeper water planktonic facies including marls and an eastern area displaying typically inner shelf carbonates and an attenuated succession coralline algal limestones and calcarenites are more typical of this latter region but there are also some volcanic intercalations an attempt is made to relate the hyblean succession to that of the maltese islands which lie at the southern end of this tertiary carbonate platform

new gps constraints on the africa eurasia plate boundary zone in southern italy 1 southern italy is a key area for understanding the tectonic processes in the africa eurasia collision zone we analyze new gps measurements carried out between 1994 and 2001 the results are presented in terms of time series trajectories and velocities of crustal motion as well as a geodetic strain rate field while central italy corsica sardinia and the tyrrhenian sea move like the eurasian plate the overall motion of the sicily rift zone region matches african plate motion unexpected are the north northwest directed motions of northeastern sicily and the eolian islands most striking on the deformation field are a north south oriented compression along the northern sicilian coast compression between apulia and northwestern greece as well as extension in the sicily rift zone and the interior of sicily

malta escarpment fault zone offshore eastern sicily pliocene quaternary tectonic evolution based on new multichannel seismic data 1 the malta escarpment represents the dominant morphological feature offshore eastern sicily linking the deep ionian basin to the east with the hyblean carbonate platform to the west interpretation of purposely acquired multichannel seismic data allows division of the malta escarpment into two portions characterized by different tectonic structures along the segment south of siracusa the malta escarpment is not affected by recent faulting and appears as a steep surface that flattens out toward the ionian basin a recent deformation characterized by a broad area of uplift occurs 20 30 km east from the slope along a nnw sse trend the segment of the malta escarpment extending north of siracusa on the other hand is characterized by the presence of nnw sse east dipping recent extensional faults and related sedimentary basins the observed structural features support the occurrence of a lithospheric tear between the ionian oceanic basin and the hyblean plateau

a geological and paleomagnetic study of the hyblean volcanic rocks sicily abstract the geological and paleomagnetic study of the hyblean volcanic rocks in southeastern sicily permits the following conclusions 1 1 the upper cretaceous volcanics are considerably more extensive than earlier studies indicated they stretch from north of augusta to the vicinity of siracusa their magnetization is identical to that of the better known outcrops around capo passero of the two new age dates reported here one is younger than any so far reported 2 2 the upper tortonian flows are normally magnetized suggesting a correlation of the carlentini formation with magnetic interval 7 the flows at the top of the tellaro formation are also normally magnetized and are tentatively correlated with the carlentini formation flows shorter reversed intervals within interval 7 may be represented by two less well dated flows 3 3 the lowest pliocene flows have an adequate stratigraphie control and their magnetization is consistent with the extrusion of the pillow lavas during the mammoth event the militello flow sequence together with the francofonte flows appear by indirect argument to lie within the oldest reversed interval i e pre kaena of the matuyama epoch the individual flows in which both normal and reversed directions have been found cannot be assigned positions in magneto stratigraphie scale 4 4 the geomagnetic pole positions are consistent with that of the african plate during the cretaceous and a european plate location during both pliocene and miocene time the pole positions are upper cretaceous 212 3 e 69 3 n upper miocene 200 9 e 82 1 n pliocene 339 3 e 85 9 n

the relationship of strain and preferred orientation of phyllosilicate grains in rocks a review abstract the calculation of strain from the preferred orientation of platy phyllosilicate grains taking strain to be homogeneous is surprisingly often successful from a pragmatic point of view although numerous theoretical objections to this procedure can be and have been raised for the calculation to succeed the original distribution of mica or clay mineral grains must be known or assumed the usual assumption that the starting distribution was random and therefore nearly uniform implies that the strain history of pelitic sediments is taken to start when the watery sediment was last stirred by waves or bioturbation or if it was laid down in still anoxic waters from the moment of first deposition it therefore includes compaction as part of the strain history which is usually neglected by structural geologists originally random distribution of clay flake orientations has been observed in recently deposited sediments in many instances and has been theoretically explained in various ways exceptions probably exist but their frequency has not been estimated biologically disturbed sediments may be brought nearer to a state of random orientation of clay flakes than they were at deposition with the exception of whole beds or concretions in which pores are early filled with cement mudrocks are almost always compacted by the weight of later deposits the strain so induced is axially symmetric about the vertical and thus about the pole of the bedding planes compaction acts on soft unconsolidated rocks but may continue with increasing overburden on rocks strengthened by cementation and by increasing interlocking of grains tectonic deformation may start early before the rock is fully compacted or it may begin only much later and the mechanisms of deformation increase in complexity with the increasing temperature and hydrostatic stress of deeper burial up to a certain level of mild metamorphism however phyllosilicate grains seem to be rather permanent if not as mineral species then at least by preservation of their constituent sheets of silica tetrahedra given this permanence the mechanisms of rock deformation whether intergranular slip cataclasis or dissolution and reprecipitation and various intragranular processes in the non phyllosilicate matrix hardly matter as far as the recording of strain is concerned even a certain amount of stress solution at especially heavily loaded points of the phyllosilicate grains themselves does not destroy their value as strain markers as long as the dissolved material is disposed of mainly by crystallographically continuous overgrowth on existing grains the same holds for local dissolution of phyllosilicates in portions of old grains that have become thermodynamically unstable by bending widespread irregular or random nucleation and growth of newly nucleated phyllosilicate grains at intermediate or high grades of metamorphism can reduce the reliability of the strain record and so can domainal structure of the deformed rock if both the volume fraction of phyllosilicate grains and the intensity of total strain differ sharply from one domain to another if distinct domains are not equant and have themselves a strong preferred orientation of shape nevertheless rocks containing an anastomosing network of zones rich in phyllosilicate grains as slates and other deformed mudrocks commonly do have in many cases been found to have average preferred orientations of mica or chlorite which if used to estimate the strain give results similar to those obtained from independent strain markers in the same rocks thus the most significant verification of the usefulness of strain estimates by measurement of preferred orientation is the mutual confirmation with independently determined strain the limit to such verification is the rarity of strain markers so that the coexistence of two independent ones is exceptionally rare for this reason however it is important to make full use of the orientation of phyllosilicate grains where they are available the alternative to have no strain measurements at all causes structural geologists to miss potential information

quaternary normal faulting in southeastern sicily italy a seismic source for the 1693 large earthquake summary we present geological and morphological data combined with an analysis of seismic reflection lines across the ionian ovshore zone and information on historical earthquakes in order to yield new constraints on active faulting in southeastern sicily this region one of the most seismically active of the mediterranean is avected by wnw ese regional extension producing normal faulting of the southern edge of the siculo calabrian rift zone our data describe two systems of quaternary normal faults characterized by diverent ages and related to distinct tectonic processes the older nw se trending normal fault segments developed up to 400 kyr ago and striking perpendicular to the main front of the maghrebian thrust belt bound the small basins occurring along the eastern coast of the hyblean plateau the younger fault system is represented by prominent nnw sse trending normal fault segments and extends along the ionian ovshore zone following the ne sw trending avola and rosolini ispica normal faults these faults are characterized by vertical slip rates of 0 7 3 3 mm yr 1 and might be associated with the large seismic events of january 1693 we suggest that the main shock of the january 1693 earthquakes m 7 could be related to a 45 km long normal fault with a right lateral component of motion a long term net slip rate of about 3 7 mm yr 1 is calculated and a recurrence interval of about 550 50 yr is proposed for large events similar to that of january 1693

the foreland deformation in the south western basque cantabrian belt spain abstract in the south western portion of the cenozoic basque cantabrian belt structural data collected in pre orogenic upper cretaceous limestones were combined with aerial images interpretation in flat lying areas observations about fracture strike type orientation and overprinting relationships both at the macro and mesoscales allow to constrain the pre thrusting and pre folding deformational sequence that affected the area when it was forming part of the foreland basin wnw ese striking extensional structures represent the oldest elements developed during the very late stages of the mesozoic rifting associated with the opening of the bay of biscay the onset of convergence is marked by the development of extensional structures striking roughly nnw sse and wsw ene which are associated with belt parallel stretching in the foredeep and outer arc extension in the peripheral bulge respectively and developed in a non fluid assisted environment these elements are postdated by a pre folding layer parallel shortening pattern which includes wsw ene striking pressure solution cleavages and reverse faults both of them frequently reactivating inherited early orogenic wsw ene striking extensional elements and right lateral reactivation of wnw ese striking pre orogenic extensional structures this stage was followed by a syn to post folding e w oriented belt parallel compression wnw ese striking left lateral faults being the most outstanding elements associated with this stage the presence of such elements in upper cretaceous sediments provides support to the idea that left lateral shear zones of the area related with a cenozoic intrabelt lateral extrusion tectonics our results indicate coherently with previously published works in the pyrenean orogen that most of the mesoscale deformation has been acquired before layer s tilting

late holocene relative sea levels near palmer station northern antarctic peninsula strongly controlled by late holocene ice mass changes abstract many studies of holocene relative sea level rsl changes across antarctica assume that their reconstructions record uplift from glacial isostatic adjustment caused by the demise of the last glacial maximum lgm ice sheets however recent analysis of gps observations suggests that mantle viscosity beneath the antarctic peninsula is weaker than previously thought which would imply that solid earth motion is not controlled by post lgm ice sheet retreat but instead by late holocene ice mass changes if this hypothesis is correct one might expect to find holocene rsl records that do not reflect a monotonic decrease in the rate of rsl fall but show variations in the rate of rsl change through the holocene we present a new record of late holocene rsl change from torgersen island near palmer station in the western antarctic peninsula that shows an increase in the rate of relative sea level fall from 3 0 1 2 mm yr to 5 1 1 8 mm yr during the late holocene independent studies of the glacial history of the region provide evidence of ice sheet changes over similar time scales that may be driving this change when our rsl records are corrected for sea surface height changes associated with glacial isostatic adjustment gia the rate of post 0 79 ka land uplift at torgersen island 5 3 1 8 mm yr is much higher than the rate of uplift recorded at a nearby gps site at palmer station prior to the larsen b breakup in 2002 ad 1998 2002 ad

a continuum mechanics model for normal faulting using a strain rate softening rheology implications for thermal and rheological controls on continental and oceanic rifting abstract we use a strain rate dependent visco plastic rheology in a finite element model to investigate the effects of crustal rheology and thermal structure on the development of normal faults in 2 d extending lithosphere strain rate softening in the brittle regime is used to simulate the rate dependence of frictional strength observed in laboratory studies results of numerical experiments show that efficient strain rate softening can result in localized zones of high strain rate which develop in response to the rheology and boundary conditions and are not imposed a priori we argue that these zones of localized shearing are analogous to faults and use the calculated deformation field to predict the preferred location of fault formation for a range of thermal and rheologic conditions when no regional temperature gradient is imposed deformation is predicted to be distributed between several sets of conjugate normal faults however in the presence of a horizontally varying temperature field faulting is calculated to focus where the lithosphere is thinnest forming rift like topography model results predict that when crustal thickness is sufficiently small that no ductile layer is present in the lower crust deformation is mantle dominated and rift half width is controlled primarily by the vertical geothermal gradient in contrast when crustal thickness is large enough that the stress accumulation in the upper crust becomes much greater than the stress accumulation in the upper mantle deformation becomes crust dominated and the calculated rift half width is a function of both crustal rheology and the vertical geothermal gradient this implies that deformation in the brittle upper crust does not behave independently of a strong upper mantle even in situations where ductile flow occurs in the lower crust

crustal image of the ionian basin and its calabrian margins abstract previous seismic investigation of the crustal structure in the ionian basin has been limited to shallow penetration seismics of the 1970 s characterized by inadequate source power and low fold earlier obs and esp seismic refraction experiments have not been able to firmly resolve one of the principal scientific problems for this region which is whether the ionian basin is floored by oceanic crust or by highly attenuated continental crust a second elusive problem is the nature of the transition of the boundaries between the ionian basin and its margins in this paper we describe and interpret new deep seismic reflection and wide angle data collected in the western ionian sea and the calabria region of italy one of the principal features of our multichannel reflection data beneath the ionian basin is a band of layered high amplitude reflections near the base of the crust this band shows a quasi monochromatic ca 8 to 10 hz frequency and a traveltime thickness of 1 to 1 5 s these images contrast with the well known reflection patterns of mesozoic oceanic crust investigated in the atlantic ocean there is evidence that the low frequency band dips down towards the edge of the malta escarpment me where landward dipping reflectors separate continental and intermediate type crust in the central tract of the me the increased traveltimes of the lower crustal reflectors and moho from the basin towards the southern and eastern margins of southern calabria could be partially due to the velocity pull down effect of the sedimentary pile of the arc although a true dip of 15 to 18 over 60 km distance can be substantiated moreover the reflecting band maintains its reflectivity and thickness until its abrupt termination beneath the ionian continuation of the calabrian compressional crustal structures the coincident acquisition of wide angle seismic data and marine reflection seismic data provided a landward extension of the survey which will complement existing geologic information on the deep framework of the ionian basin and its calabrian margin

petroleum exploration in italy a review abstract petroleum exploration in italy began in the second half of the 19th century but the first consistent discoveries were only made after world war ii at present the original reserves of the italian petroleum fields amount to about 160 million tons of oil and 720 billion cubic metres of gas domestic production in 1990 was 4 6 million tons of oil and 17 3 billion cubic metres of gas the lithology of the italian sedimentary sequences was controlled by the geodynamic evolution of the western margin of the adria plate the permian triassic continental and shallow water environments pre dating the break up of pangea were followed by subsiding carbonate platforms and basins in the mesozoic tertiary compressive tectonics induced by the subduction of the adria continental margin produced a complex thrust belt bordered by a migrating foredeep filled with clastic sediments most of the oil and a minor part of the gas were generated by middle triassic lower jurassic shaly and carbonate source rocks most of the gas was sourced by pliocene pleistocene clays in the foredeep turbiditic deposits and has a bacterial origin a short review integrated with some actual examples of typical fields cortemaggiore costa molina settala agostino porto garibaldi barbara candela palino rospo vega exemplifies the different plays in the main tectonic domains

the origin of tectonic fabrics in undeformed clays the early stages of deformation in extensional sedimentary basins 1 an integrated approach was used to detect tectonic effects in apparently undeformed fine grained clay sediments filling extensional basins in southern italy results from low and high field anisotropy of magnetic susceptibility and mineral fabric deduced by neutron texture analysis show penetrative deformation on a grain scale the well defined tectonic magnetic lineation is parallel to the stretching direction and located at the intersection of the basal planes of phyllosilicates forming grain scale folds and crenulations this spatial configuration reflects basin scale deformation processes and suggests the existence of a nearly uniaxial stress field during the incipient extensional phases the integrated approach of magnetic and mineral fabric investigations is a valid tool to detect grain scale and regional deformation pattern in weakly deformed extensional basins where macroscopic evidence of deformation is not visible

changes in tropical pacific thermocline depth and their relationship to enso after 1999 abstractthe characteristics of el nino southern oscillation enso variability have experienced notable changes since the late 1990s including a breakdown of the zonal mean upper ocean heat content as a precursor for enso these changes also initiated a debate on the role of thermocline variations on the development of enso events since the beginning of the twenty first century in this study the connection between thermocline variations and el nino and la nina events is examined separately for the 1980 98 and 1999 2012 periods the analysis highlights the important role of thermocline variations in modulating enso evolutions in both periods it is found that thermocline variation averaged in the central tropical pacific including both equatorial and off equatorial regions is a good precursor for enso evolutions before and after 1999 while the traditional basinwide mean of equatorial thermocline variation is a good precursor only before 1999 the new precursor including both high frequency variabili