neogene tectonostratigraphy and kinematics of calabrian basins implications for the geodynamics of the central mediterranean abstract a new structural model for the calabrian arc southern italy is presented based on a systematic analysis of basin kinematics combined with a review of the literature on basement structure three tectonic patterns can be distinguished a nw se trending oblique thrust zones determining a set of n130 trending segments b sw ne to e w trending thrust zones and c radial and concentric tensional fault systems in the southern tyrrhenian back arc area these faults combined with dome shaped uplift centres determine the actual arc patterns a and b can be regarded as the on shore representation of the calabrian accretionary wedge system the kinematics of various types of basins such as piggy back pull apart and complex oblique strike slip basins are connected to these patterns the patterns a and b can be linked to the middle miocene early pliocene development of oblique convergent crustal shear zones strike slip cycle whereas pattern c can be linked to the pleistocene collapse of the southern tyrrhenian basin and concentric uplift of the arc our structural model has considerable implications for the understanding of the kinematic evolution of the central mediterranean we propose a model in which the evolution is characterized by an alternation of the translation of the calabrian lithosphere element either to the southeast gravitationally or to the northeast compression combining a our analyses of basin evolution b the structural model and c some considerations concerning kinematics of the central mediterranean with the geodynamic mechanisms as proposed in literature we present a model which consists of a geodynamic cycle comprising the following three stages 1 a tension stage with back arc basin opening related to the diapiric inflow of asthenosphere material and roll back of the subducted ionian slab resulting in gravitational displacement of the calabrian element to the southeast 2 a transpression stage with oblique overthrusting towards the northeast upon the southern apennines and 3 a compression stage with ne sw compression due to oblique dextral shear along the north african margin plate rupture lithosphere split and back arc basin collapse

microbial sulfate reduction within the iheya north subseafloor hydrothermal system constrained by quadruple sulfur isotopes abstract subseafloor hydrothermal systems may host spatially extended and numerically abundant microbial communities sustained by sulfate reduction as one of the important terminal electron accepting metabolisms in order to estimate microbial sulfate reduction in a subseafloor hydrothermal regime we analyzed sulfur isotopes s 32 s 33 s 34 s 36 of pore water sulfate and mineralized sulfide in the upper 100 m of sedimentary sequences at the iheya north hydrothermal field in the okinawa trough recovered in integrated ocean drilling program expedition 331 iodp exp 331 on the basis of the pore water chemistry and temperature profiles the subseafloor environment is divided into three hydrogeologic units in the topmost unit 1 relatively fresh seawater is recharged and the bottommost unit 3 is characterized by predominance of endmember like high temperature hydrothermal fluid 300 c underlying the impermeable cap rock layers intermediate unit 2 is subject to mixing between the hydrothermal fluid and seawater the 34 s values of sulfate in the unit 2 mixing zone were found to be more 34s enriched than the values expected from simple mixing model of seawater sulfate in the unit 1 with the hydrothermal fluid in the unit 3 the observed s so 4 34 enrichment and sulfate concentration so2 4 depletion suggest sulfate reduction is taking place below the seafloor based on our model calculation the isotope discrimination e 34 is estimated to be 21 this large isotope discrimination together with slight 33 s enrichment and 36 s depletion reveals that sulfate reduction is caused by microbial processes but not by thermochemical processes in addition our numerical simulation points out that sulfate may be reduced prior to presently undergoing mixing with high temperature fluid probably within the seawater recharge zone despite the abundant input of hydrothermal h2s mineralized sulfide below 10 m seafloor mbsf shows characteristic sulfur isotopic signatures that support the significant contribution of subseafloor microbial sulfate reduction potentially corresponding to approximately 20 of the total sulfide mineral formation active microbial sulfate reduction below the seafloor may be promoted by significant input of seawater to the habitats through the vigorous hydrothermal circulation in vicinity of iheya north field

correlation of diagenetic data from organic and inorganic studies in the apenninic maghrebian fold and thrust belt a case study from eastern sicily abstract temperature dependent clay mineral assemblages and vitrinite reflectance data have been used to investigate levels of diagenesis from the apenninic maghrebian fold and thrust belt in eastern sicily at the footwall of the peloritani calabride arc data are from units sampled along a regional transect between the nebrodi mountains to the north and mount judica to the south these units developed in very different tectonic settings from those of oceanic to passive continental margin domains deformed during the cenozoic mountain building and related active margin deposits the integration of organic and inorganic thermal indicators allowed us to distinguish among different tectonic settings with thermal maturity generally decreasing from hinterland to foreland as a result of progressively less severe thermal evolution and or tectonic loading during the mountain building specifically the highest vitrinite reflectance vro values ca 0 60 0 75 and percentages of illite layers in illite smectit

controls on sonic velocity in carbonates compressional and shear wave velocities v p and v s of 210 minicores of carbonates from different areas and ages were measured under variable confining and pore fluid pressures the lithologies of the samples range from unconsolidated carbonate mud to completely lithified limestones the velocity measurements enable us to relate velocity variations in carbonates to factors such as mineralogy porosity pore types and density and to quantify the velocity effects of compaction and other diagenetic alterations

fluid flow compartmentalization in the sicilian fold and thrust belt implications for the regional aqueous fluid flow and oil migration history abstract the fluid flow history in the frontal part of the sicilian fold and thrust belt ftb has been reconstructed using an integrated structural petrographic geochemical and microthermometric approach the study focused on comparing fluid flow during progressive deformation along major thrust horizons and in pelagic sediments occurring in the associated thrust sheets foot and hanging wall a fluid flow model is constructed for the frontal part of the sicilian ftb syn deformational quartz and calcite have been precipitated along decollement horizons in the iudica scalpello study area the microthermometric analysis of fluid inclusions in the quartz and calcite indicated migration of low saline high temperature aqueous fluids 1 5 h the fluid flow history in the thrust sheets can be subdivided into two stages calcite of types 1 and 2 has identical light orange cathodoluminescence as the surrounding mudstone furthermore its isotope signature 2 13 c 18 o m h between 80 and 140 c type 3 calcite has less depleted 18 o values compared to calcite of types 1 and 2 and the 18 o from calcite in faults is even positive during the final stages of fluid flow with precipitation of calcite type 3 the fluid flow model invokes infiltration of overpressured fluids that migrated along the decollement zone these fluids only infiltrate the thrust sheet in the hanging wall of the thrust leading to a compartmentalized fluid flow pattern an identical fluid flow pattern with migration of low and hot saline fluids associated with hydrocarbons was observed in other parts of the sicilian fold and thrust belt with identical structural deformation and fluid flow patterns the study confirms the suitability of the frontal part of the sicilian fold and thrust belt as an outcrop analog for deeply submerged accretionary prisms the study thus offers unique insights in expected fluid flow patterns in thrust sheets of deeply submerged accretionary complexes

rifted margin formation in the south tyrrhenian sea a high resolution seismic profile across the north sicily passive continental margin a new 150 km long seismic line across the continental margin of north sicily has been acquired and interpreted the overall structure of the margin is controlled by extension which caused crustal thinning and widespread normal faulting two main thinned zones are observed in the south in correspondence with the cefalu basin and farther to the north at the continent ocean transition zones of thinned crust coincide with zones of intense normal faulting extension began in late tortonian times and caused the opening of the cefalu basin controlled by a northward dipping listric fault messinian stretching affected most of the future margin and provoked a widening of the cefalu basin and normal faulting in the north following a phase of relative quiescence in the early pliocene renewed extension determined further opening of the cefalu basin and subordinate normal faulting in the north here however the record is unclear because of the emplacement of the calc alkaline sisifo volcano with associated volcanoclastic deposits breakup took place in the late pliocene and was followed by the deposition of postrift pleistocene sediments at the lithospheric scale the sites of extension thinning did not migrate during rifting on the smaller scale on the contrary the cefalu basin displays a remarkably systematic pattern of migration toward the foot wall of the listric fault which controlled the opening of the basin the spacing of 4 6 km between faults is also quite systematic elongation experienced by the continental part of the margin presently 97 km has been derived by comparing the present day and the preextensional lengths and is 10 km the corresponding strain rate is 5 10 16 s 1

rare earth elements absorption patterns in grapevine vitis vinifera l cultivated in carbonate terrains south eastern sicily italy vitis vinifera l vineyards grown on carbonate soil hyblean plateau se sicily have been characterized in terms of rare earth elements rees distribution results highlighted that the absorption of rees by plants depends on the composition of the underlying soil which in this case derives from limestone parent rock allowing us to recognize the area of origin indeed even slight differences in rees content in soils may affect the absorption pattern of each grapevine cultivar importantly the various parts of the plants showed differences in rees absorption such rees fractionation is particularly evident in the leaf and juice samples in general the uptake and concentrations of rees in plant tissues may be related to many factors such as geographical climatic and lithological features this is also pointed out by the statistical investigation which took into account either the grapevine variety or each part of the plant by taking into consideration both the grape variety and the type of soil the present multi elemental approach aims to provide a useful geochemical tool for assessing the geographical origin of the production area of wine

the southernmost margin of the tethys realm during the mesozoic and cenozoic initial geometry and timing of the inversion processes 1 along the northern border of africa pangea breakup has been diachronic during the jurassic the alpine tethys propagated northeastward from the atlantic to the alps during the permian the neo tethys propagated westward from oman to northwestern arabia then a secondary and late branch of neo tethys gave birth to the east mediterranean basin finally the two oceans connected at end of jurassic times achieving the development of africa northern plate boundary by the late cretaceous convergence between africa and eurasia led to the progressive closure of the tethys realm the continental collision is not completely achieved and the different segments of the confrontation zone maghreb central and east mediterranean zagros and oman expose different stages of the process however we emphasize the existence of synchronous geodynamic events from one end of the system to the other although they do not have the same meaning two of them are particularly important the campanian santonian c s event corresponds to 1 obduction and exhumation of high pressure low temperature metamorphic rocks around the arabian promontory 2 inversion along the margins of the east mediterranean basins and 3 lithosphere buckling in the atlas system maghreb and adjacent sahara platform the middle late eocene mle event corresponds to 1 the onset of collision at the northern corner of arabia 2 the onset of slab retreat in the mediterranean and 3 inversion along the margin of the east mediterranean as well as in the atlas the c s event coincides with a change in plate kinematics resulting in an abrupt increase of convergence velocity the mle event coincides with a period of strong coupling between the africa and eurasia plates and an abrupt decrease of convergence velocity in the middle of the system the central mediterranean seems to escape to the effects of convergence and is the site of quite permanent extensional movements since the triassic

seismotectonics of the nubia plate compressive margin in the south tyrrhenian region italy clues for subduction inception 1 seismological and structural data are used to constrain the active tectonics of the nubia plate compressive margin in southern italy in this region compressional displacements have resumed at the rear of the maghrebian orogenic wedge since about 700 500 ka and are presently accommodated along a seismic belt in the south tyrrhenian area where a passive margin has developed during late neogene quaternary times earthquake data from the south tyrrhenian belt are analyzed with bayloc a probabilistic nonlinear location method results show that the seismic belt is segmented and involves a series of ne sw and nw se elongated clusters the ne sw clusters are interpreted as high angle reverse fault zones verging toward the southeast whereas the perpendicular clusters are interpreted as possible strike slip fault zones transferring the contractional displacements to advanced segments of the belt in the southeast brittle deformations observed in the quaternary volcanic island of ustica are consistent with the geometry and kinematics of the seismic belt deduced from the seismological data the south tyrrhenian active belt may constitute an early stage of subduction of the tyrrhenian oceanic crust beneath sicily a similar scenario has been hypothesized also for the westward prolongation of the south tyrrhenian belt off the algerian coast by integrating instrumental and historical seismic data with tectonic evidences we infer that the south tyrrhenian belt is probably capable of producing earthquakes with a maximum size close to magnitude 7 the analyzed data suggest a multifault system behavior for the studied compressional belt this inference is important to estimate and mitigate the seismic and tsunamic hazards in such a densely populated region

on the computation of darcian velocity and mass balance in the finite element modeling of groundwater flow darcian velocity has been conventionally calculated in the finite element modeling of groundwater flow by taking the derivatives of the computed pressure field this results in discontinuities in the velocity field at nodal points and element boundaries discontinuities become enormous when the computed pressure field is far from a linear distribution it is proposed in this paper that the finite element procedure that is used to simulate the pressure field or the moisture content field also be applied to darcy s law with the derivatives of the computed pressure field as the load function the problem of discontinuity is then eliminated and the error of mass balance over the region of interest is much reduced the reduction is from 23 8 to 2 2 by one numerical scheme and from 29 7 to 3 6 by another for a transient problem

seismotectonics of the calabrian arc abstract relocation of intermediate and deep earthquakes of tyrrhenian sea area through joint hypocenter determination for the period 1962 1979 has allowed a more detailed definition of the geometry of this peculiar benioff zone earthquakes dip along a quasi vertical plane to 250 km depth there is a 50 dip in the 250 340 km depth range and a low dip angle to 480 km depth the structure sketched from the hypocenters is almost continuous but most energy has been released in the 230 340 km depth interval an evaluation of fault plane solutions of intermediate earthquakes in this area indicates predominance of down dip compressions in the central part of the slab at the border strike slip motion occurs independent of depth some earthquakes that occurred at intermediate depth less than 100 km along the ionian margin of calabria show predominance of reverse faulting with the p axis oriented se nw however shallow earthquakes in the calabria sicily region indicate a more complex motion with predominance of normal faulting a possible interpretation of these features according to the available geological history which involves subduction of continental lithosphere is discussed

plio quaternary segmentation of the south tyrrhenian forearc basin the structural elements constituting the forearc basin of the calabrian arc sicily orogenic system are recognizable on land and in the tyrrhenian offshore the plio pleistocene retreat of the ionian subduction hinge coeval with the roll back of the africa continental crust leads to segmentation of the forearc basin and southeastward migration of the calabrian arc due to its higher degree of mobility compared to sicily where on the contrary continental collision takes place the analysis of geological data collected in three areas of the orogenic belt and the integration with offshore geophysical data show evidence of two phases of subduction hinge retreat 1 late pliocene early pleistocene southeastward migration accompanied by the development of n120 e trending tear faults and ne sw trending extensional systems 2 middle late pleistocene sse ward migration with development of nnw sse trending tear faults and n70 e trending collapse systems the data presented here provide an innovative framework for the interpretation of this most seismically active area of the mediterranean in particular in the messina strait area the more recent n70 e lineaments could be associated with the faults that generated the 1783 calabria earthquake and are coherent with the focal mechanism of the 1908 messina earthquake confirmed also by the analysis of frequency diagrams of the elongation directions of the isoseists

structural and tectono stratigraphic review of the sicilian orogen and new insights from analogue modeling abstract the apennines sicilian maghrebian fold and thrust belt originated from the subduction of the alpine tethys and the later collision of drifted continental blocks against the african and apulian paleomargins from north to south the sicilian fold and thrust belt sftb is divided in four main tectono stratigraphic domains 1 the calabro peloritani terrane drifted from the european margin 2 the remnants of the alpine tethys accretionary wedge atw related to the subduction of the tethys 3 the folded and thrusted platform panormide and deep water imerese sicanian series of the offscrapped african margin and 4 the african foreland hyblean unfortunately scarce quality seismic lines and outcrops of key tectono stratigraphic units make the structure and dynamic evolution of the central eastern part of the sftb controversial first this study outlines through a review of the tectono stratigraphic evolution of the central eastern sector of the sicilian orogen the major remaining issues concerning 1 the occurrence of inferred alpine tethys units far from the region where the remnants of the atw outcrop nebrodi mountains both in a forearc position above the peloritani block to the north and in an active foreland context along the present day southern front of the belt and 2 the diverging tectonic styles from stacked large scale tectonic nappes to foreland imbricated thrust systems rooted into a main basal decollement secondly new constraints are given using analogue modeling to test mechanically the hypothesized structural and tectono stratigraphic evolution of the sftb the experiment simulates the orogenic evolution of the sftb at crustal scale from the oligocene tethys subduction to the middle miocene late pliocene continental collision between the european and african paleomargins the tectono stratigraphic synthesis is used to model the first order mechanical stratigraphy of the sedimentary units involved in the sicilian belt as well as the imprint of the african margin structural inheritance the experiments succeed in reproducing the general structure and tectono stratigraphic evolution of the sftb in particular the models support field observations hypothesing a gravity driven origin of the inferred alpine tethys units intercalated within the forearc and foreland syntectonic sedimentation moreover the model testifies of the main tectonic steps that led to the sftb building first a low tapered accretionary wedge was accreted above the alpine tethys oceanic crust from the oligocene to the early miocene the following underthrusting of the stretched african continental margin and its frontal panormide platform shortened and thickened the accretionary wedge this phase provided favorable conditions for significant pulses of reworked alpine tethys units that intercalated within the forearc and foredeep successions during the middle miocene the decollement of the african meso cenozoic cover panormide platform and imerese sicanian deep water basin enhanced a deep seated deformation phase along with duplexing of the panormide platform beneath the alpine tethys wedge leading to its emersion since the late messinian activation of basement faults led to a generalized emersion of the orogenic units through large wavelength fold culminations accompanied by syn tectonic deposition at their southern limbs concurrently the prism front was partly indented to the southeast by the thick and locally already emerged hyblean platform

locally conservative groundwater flow in the continuous galerkin method using 3 d prismatic patches a new procedure has been developed to improve the velocity field computed by the continuous galerkin finite element method cg it enables extending the postprocessing algorithm proposed by cordes and kinzelbach 1992 to three dimensional 3 d models by using prismatic patches for saturated groundwater flow this approach leverages a dual mesh to preserve local mass conservation and provides interpolated velocities based on consistent fluxes to develop this 3 d approach a triangular conservative patch is introduced by computing not only advection fluxes but also vertical infiltrations storage changes and other sink or source terms this triangular patch is then used to develop a prismatic patch which consists of subprisms in two layers by dividing a single two layer patch into two separate one layer patches two dimensional 2 d algorithms can be applied to compute velocities as a consequence each subelement is able to preserve local mass conservation a hypothetical 3 d model is used to evaluate the precision of streamlines and flow rates generated by this approach and the feflow simulation program

crustal structure and seismotectonics of central sicily southern italy new constraints from instrumental seismicity summary in this paper we propose a new model of the crustal structure and seismotectonics for central sicily southern italy through the analysis of the depth distribution and kinematics of the instrumental seismicity occurring during the period from 1983 to 2010 and its comparison with individual geological structures that may be active in the area the analysed data set consists of 392 earthquakes with local magnitudes ranging from 1 0 to 4 7 we defined a new detailed 1 d velocity model to relocate the earthquakes that occurred in central sicily and we calculated a moho depth of 37 km and a mean vp vs ratio of 1 73 the relocated seismic events are clustered mainly in the area north of caltanissetta e g mainland sicily and in the northeastern sector madonie mountains of the study area only minor and greatly dispersed seismicity is located in the western sector near belice and along the southern coast between gela and sciacca the relocated hypocentral distribution depicts a bimodal pattern 50 per cent of the events occur within the upper crust at depths less than 16 km 40 per cent of the events occur within the middle and depth crust at depths between 16 and 32 km and the remaining 10 per cent occur at subcrustal depths the energy release pattern shows a similar depth distribution on the basis of the kinematic analysis of 38 newly computed focal plane solutions two major geographically distinct seismotectonic domains are distinguished the madonie mountain domain with prevalent extensional and extensional oblique kinematics associated with upper crust late pliocene quaternary faulting and the mainland sicily domain with prevalent compressional and compressional oblique kinematics associated with thrust faulting at mid to deep crust depth along the north dipping sicilian basal thrust sbt the stress inversion of the mainland sicily focal solutions integrated with neighbouring mechanisms available in the literature highlights a regional homogeneous compressional tensor with a subhorizontal nnw sse striking 1 axis in addition on the basis of geodetic data the mainland sicily domain may be attributed to the sse ward thrusting of the mainland sicily block along the sbt plane seismogenic shearing along the sbt at mid crustal depths was responsible for the unexpected belice 1968 earthquake mw 6 1 with evident implications in terms of hazard assessment

contemporaneous thrusting and large scale rotations in the western sicilian fold and thrust belt in the western sicilian fold and thrust belt large clockwise rotations of allochthons occurred during late cenozoic contraction of part of the southern tethyan margin the magnitude of rotation decreases stepwise from over 120 in the upper sheets lying on the north coast of sicily to no appreciable rotation in the frontal portion of the belt flanking the southern coast of the island the allochthons are composed of imbricate thrust sheets derived primarily from individual basin and platform assemblages of the old tethyan margin paleomagnetic and structural data indicate that the rotation of the allochthons was accommodated by coherent torsional displacements on relatively low angle detachment surfaces timing relations for the imbrication history of the sicilian fold and thrust belt are derived from stratigraphic overlap and local involvement of sediments deposited in a series of foreland and piggyback basins the locus of deposition within successive foreland basins first migrated easterly then southerly during progressive deformation in the orogen imbrication began in the early miocene burdigalian langhian and continued at least through the early pleistocene and appears to be continuing today rotation is related to thrusting and accompanies a 70 change in the tectonic transport direction from easterly to southerly easterly striking right oblique transpressional faults and associated northeasterly trending folds postdate thrust sheet rotation in the interior of the thrust belt and were active contemporaneously with south directed thrusting in the foreland region pleistocene and possibly older late pliocene extension strongly modified the older thrust morphology along the tyrrhenian coast of northwestern sicily with the development of down to the north listric normal faults the extensional structures apparently are related to the opening and subsequent deformation of the tyrrhenian sea to the north

pattern of orogenic rotations in central eastern sicily implications for the timing of spreading in the tyrrhenian sea new palaeomagnetic data from upper triassic to pliocene sediments reveal that in eastern sicily a major 70 clockwise cw rotation took place between oligocene and late tortonian time followed by a further 30 cw rotation results from central sicily are less coherent they show 44 83 post oligocene cw rotation local 14 post late tortonian counterclockwise ccw rotation and 25 post mid pliocene cw rotation we interpret the larger cw rotation observed in eastern sicily as related to a more internal palaeogeographical position with respect to central sicily our results complement pre existing data from the northwestern sicily carbonates and indicate that all the internal carbonate nappes coherently rotated by c 100 cw during tectonic emplacement implying a west to east increase of shortening in the sicilian maghrebian belt in sicily compressive deformation started during the langhian i e just after the deposition of the upper oligocene upper burdigalian numidian flysch turbidites therefore the age of the older 70 palaeomagnetic rotation synchronous to the thrusting is constrained to occur between the langhian and late tortonian furthermore by considering a maximum possible rotation rate of 20 ma 1 we infer that cw rotation started in sicily in langhian serravallian times between 15 16 and 11 12 ma ago the 100 cw rotation observed in pre orogenic strata from the whole of sicily is mirrored by 80 orogen scale ccw rotations characterizing the internal southern apennines palaeomagnetism therefore shows that during orogenesis the southern apennines and the sicilian maghrebides rotated in a saloon door fashion synchronous to back arc spreading of the southern tyrrhenian sea consequently our palaeomagnetic data suggest that the southern tyrrhenian back arc basin started to spread during langhian serravallian times from 15 16 to 11 12 ma significantly earlier than the late tortonian age 8 ma suggested so far by oceanic drilling data

geothermal resources within carbonate reservoirs in western sicily italy a review abstract low to medium temperature fluid reservoirs hosted in carbonate rocks are some of the most promising and unknown geothermal systems western sicily is considered a key exploration area this paper illustrate a multidisciplinary and integrated review of the existing geological geochemical and geophysical data mainly acquired during oil and gas explorations since the 1950s specifically re analyzed for geothermal purposes has led to understanding the western sicily geothermal system as a whole and to reconstructing the modalities and particular features of the deep fluid circulation within the regional reservoir the data review suggests the presence of wide groundwater flow systems in the reservoir beneath impervious cap rocks we identified the main recharge areas reconstructed the temperature distribution at depth recognized zones of convective geothermal flow and depicted the main geothermal fluid flow paths within the reservoir we believe that our reconstruction of geothermal fluid circulation is an example of the general behavior of low to medium enthalpy geothermal systems hosted in carbonate units on a regional scale due to the recent technological developments of binary plants these systems have become more profitable not only for geothermal direct uses but also for power production

flow computation and mass balance in galerkin finite element groundwater models in most groundwater modeling studies quantification of the flow rates at domain and subdomain boundaries is as important as the computation of the groundwater heads the computation of these flow rates is not a trivial task when a finite element method is chosen to solve the groundwater equation generally it is believed that finite element methods do not conserve mass locally in this paper a postprocessing technique is developed to compute mass conserving flow rates at element faces it postprocesses the groundwater head field obtained by the galerkin finite element method and the calculated flow rates conserve mass locally and globally the only requirement for the postprocessor to be applicable is the irrotationality of the flow field i e the curl of the darcy flux should be zero the accuracy and the mass conservation properties of the new postprocessor are demonstrated using several test problems that include one two and three dimensional flow systems in both homogeneous and heterogeneous aquifer conditions

gps velocity and strain fields in sicily and southern calabria italy updated geodetic constraints on tectonic block interaction in the central mediterranean 1 we present an improved rendition of the geodetic velocity and strain fields in sicily and southern calabria obtained through the analysis of 18 years of gps observations from continuous and survey station networks the dense spatial coverage of geodetic data provides precise quantitative estimates of previously established first order active kinematic features including i a narrow east west elongated belt of contraction 1 1 5 mm yr extending offshore northern sicily from ustica to stromboli across the aeolian islands ii a narrow east west trending contractional belt located along the northern rim of the hyblean plateau in southern sicily with shortening at up to 4 4 mm yr iii right motion 3 6 mm yr on the aeolian tindari letojanni fault atlf system a main shear zone extending from the aeolian islands to the ionian coast of sicily with significant transpression and transtension partitioned between discrete sectors of the fault iv transtension 1 mm yr across the sicily channel between sicily and north africa we use geodetic observations coupled to geological constraints to better elucidate the interplay of crustal blocks revealed in the investigated area in particular we focus on the atlf which forms the primary boundary between the sicilian and calabrian blocks the atlf juxtaposes north south contraction between sicily and the tyrrhenian block with northwest southeast extension in northeastern sicily and calabria contraction between sicily and tyrrhenian blocks probably arises from the main europe nubia convergence although sicily has a component of lateral motion away from nubia we found that convergence is not restricted to the northern offshore as commonly believed but is widely accommodated between the frontal belt and the northern rim of the hyblean foreland in southern sicily geodetic data also indicate that active right shear on the atlf occurs to the southeast of the mapped fault array in northern sicily suggesting the fault cuts through till the ionian coast of the island the small geodetic divergence between the hyblean and apulian blocks rimming on both sides the calabria block and subjacent ionian slab coupled with marine geophysical evidences in the ionian sea lends credit to the proposed deep root of the atlf and to a fragmentation of the ionian domain

structural analysis and miocene to present tectonic evolution of a lithospheric scale transcurrent lineament the sciacca fault sicilian channel central mediterranean sea abstract seismo stratigraphic and structural analysis of a large number of multichannel seismic reflection profiles acquired in the northern part of the sicilian channel allowed a 3 d reconstruction of a regional ns trending transfer zone which displays a transcurrent tectonic regime and that is of broad relevance for its seismotectonic and geodynamic implications it is constituted of two major transcurrent faults delimiting a 30 km wide mostly undeformed basin the western fault capo granitola does not show clear evidence of present day tectonic activity and toward the south it is connected with the volcanic area of the graham bank the eastern fault sciacca is structurally more complex showing active deformation at the sea floor particularly evident along the nerita bank the sciacca fault is constituted of a master and splay faults compatible with a right lateral kinematics sciacca fault is superimposed on an inherited weakness zone a mesozoic carbonate ramp which borders to the east a 2 5 km thick plio quaternary basin and that was reactivated during the pliocene a set of scaled claybox analogue models was carried out in order to better understand the tectonic processes that led to the structural setting displayed by seismic data tectonic structures and uplift subsidence patterns generated by the models are compatible with the 3 d model obtained from seismic reflection profiles the best fit between the tectonic setting deriving from the interpretation of seismic profiles and the analogue models was obtained considering a right lateral movement for the sciacca fault nevertheless the stress field in the study area derived from gps measurements does not support the present day modelled right lateral kinematics along the sciacca fault moreover seismic events along this fault show focal mechanisms with a left lateral component we ascribe the slip change along the sciacca fault from a right lateral transcurrent regime to the present day left lateral kinematics to a change of principal horizontal stress direction starting from late pliocene

coexisting tectonic settings the example of the southern tyrrhenian sea we performed geodetic strain rate analyses in southern italy using new gps velocities two dimensional strain and rotation rate fields were estimated and results show that most of the shortening is distributed in the northern sicily offshore extension becomes more evident and comparable with shortening on the eastern side of the same margin and greater in the eastern sicily offshore principal shortening and extension rate axes are consistent with long term geological features seismic reflection profiles show both active compressive and extensional faults affecting pleistocene strata we show evidence for contemporaneous extension and transtension in the cefalu basin combining geodetic data and geological features point to the coexistence of independent geodynamic processes i e the active e w backarc spreading in the hangingwall of the apennines subduction zone and shortening along the southern margin of the tyrrhenian backarc basin operated by the nnw motion of africa relative to eurasia

structural evolution of the sedimentary accretionary wedge of the alpine system in eastern sicily thermal and thermochronological constraints temperature dependent clay mineral assemblages vitrinite reflectance and apatite fission track data have been used to investigate levels of diagenesis and time of exhumation of the double verging sicilide antisicilide accretion ary wedge in eastern sicily the integration of organic and inorganic thermal indicators allowed us to distinguish parts of the accre tionary wedge with different thermal signature and evolution we recognize a warmer core made up of the mount soro and troina units and two colder rims antisicilide and far traveled sicilide units the antisicilide unit was thrust back toward the hinterland and the far traveled sicilide units were gravity driven toward the hyblean plateau in detail the highest percentages of vitrinite reflectance vr o values 0 60 0 96 and percentages of illite layers in illite smectite i s 60 85 are found in the mount soro and troina units apatite fission track data together with the paleotemperature estimates from vitrinite reflectance data and clay mineral based geothermometers indicate that fission tracks were partially to totally annealed during wedge accretion and that the subsequent exhumation occurred mainly in burdigalian times low vr o values 0 35 0 50 and percentages of illite layers in i s 30 60 occur in early thrust top deposits reitano flysch that unconformably overlie the sicilide complex as well as the far traveled sicilide and antisicilide units apatite fission track data for the antisicilide unit confirm low paleo temperature values thus the far traveled sicilide and antisicilide units were probably at higher structural levels in the original accretionary prism and were remobilized since late aquitanian burdigalian times

structural constraints on the tertiary plate tectonic evolution of italy abstract eight cross sections six of which were balanced and restored using the principles of thin skinned tectonics demonstrate the reinterpretation of the apennine and sicilian mountains as a detached fold and thrust belt the thin skinned interpretation constrains the extent of the restored continental margins and the amount percentage direction and timing of tectonic shortening allowing the development of a plate tectonic model late cretaceous and paleogene subduction to the north beneath the corsica sardinia calabria csc microplate causes rifting from se france and the development of oceanic crust between the two in the oligo miocene the late oligocene collision of adria and northernmost csc pins the northern edge of the csc plate causing its counter clockwise rotation and its mid miocene suturing between italy and sicily the n s convergence of africa and europe with counter clockwise rotation of italy causes shortening in the nne ssw direction in italy and sicily from 20 10 ma the n s compression extrudes calabria to the se causing mio pliocene compression in southern italy and eastern sicily at the same time as extension and alkaline volcanism in central italy

mount etna dense array local earthquake p and s tomography and implications for volcanic plumbing inversion for the three dimensional velocity structure of mount etna is performed with a data set of arrival times of p and s waves of local earthquakes from temporary dense arrays of three component seismographs a high v p body revealed by the original tomography without nearby stations is confirmed and its image is sharpened using new velocity constraints provided by refraction data synthetic tests of v p and v p v s and comparison with an independent artificial source tomography with a fundamentally different geometry consistently calibrate the significance threshold of the resolution indicators the trustworthy part of the image shows a high v p body centered under the southern part of valle del bove above the 6 km below sea level deep basement which extends towards sea level and may be rooted in or through the crust it has a large contrast of over 1 km s with the surrounding sediments and sharp lateral limits and can thus be regarded as made of intrusive material of magmatic origin the massive high v p body is heterogeneous in v p v s the regions inside it where v s is relatively low can then be suspected of containing a proportion of melt or be fractured and act as pressure links or transport zones such features may be structurally linked and appear to be activated in eruptive phenomena by taking into account the heterogeneities in structure and physical state retrieved by seismic tomography a succession of seismic events deformational episodes and geochemical variation in lavas can be discussed with respect to the well observed eruptions

origin of light hydrocarbons in gases from mud volcanoes and ch4 rich emissions abstract this paper presents new chemical data of hydrocarbon rich gases discharged from mud volcanoes and ch4 rich emissions located in different areas of italy northern apennines and sicily the determination of c5 c10 alkanes cyclics and aromatics was carried out by gc ms while the main gas species and c1 c4 hydrocarbons were analyzed by gc tdc and gc fid respectively methane is by far the most abundant component of all the investigated gas emissions with the exception of part of those discharging close to mt etna volcano which are co2 rich the gas samples collected from the emilia apennine and sicily show d ch4 and 13c ch4 values typical of thermogenic gases most gases from the romagna apennine discharge methane with a biogenic isotopic signature non methane hydrocarbons of biogenic gases are almost exclusively c2 c4 alkanes with minor amounts fraction of mol mol of c4 compounds including few aromatics and cyclics likely deriving from minor thermogenic contribution not evidenced by the 13c ch4 and d ch4 values the etnean gases whose r ra and 13c co2 values indicate a strong contribution from a hydrothermal fluid source related to the nearby volcanic system show a significant enrichment of aromatics compounds up to 36 of the non methane organic gas fraction which is likely produced by catalytic reforming processes such as dehydrocyclization of alkanes the thermogenic gases from the apennines and southwestern sicily are characterized by the presence of more than 20 different cyclic compounds with concentrations up to several mol mol cyclic compounds are likely formed by i thermal cracking and ii uncompleted aromatization of alkanes occurring at depth 3 km and temperatures not exceeding 120 150 c

reply to the comment on carbonate deposition and diagenesis in evaporitic environments the evaporative and sulphur bearing limestones during the settlement of the messinian salinity crisis in sicily and calabria by caruso et al 2015 palaeo3 429 136 162 abstract manzi et al in press took the opportunity offered by our paper to repeat again all the set of ideas supporting an interpretative model of the messinian salinity crisis msc a model they assert to be valid for the whole mediterranean basin what emerges from reading this long comment may be summarized in one criticism of our article we have not systematically applied their interpretative model to our data the aim of our paper was not to promote their ideas but to submit the results of more than 20 years of field studies and petrographical and geochemical analyses on sicilian and calabrian sequences of the messinian calcare di base it is out of our purpose to enumerate again in this reply the data and interpretations we have developed in our paper which disagree with their model and rule out most of their propositions thus we will not reply in detail to this repetitive stream of ideas supporting their model but we want to respond to some general and unfair comments which are often far away from objectivity and rectify some inaccurate assertions about the description of some sections

permian circumpacific deep water faunas from the western tethys sicily italy new evidences for the position of the permian tethys abstract circumpacific deep water faunas characterized mainly by radiolarians paleopsychrospheric ostracods and conodonts were found in the early middle and late permian deposits pertaining to the sicanian paleogeographic domain of western sicily near the western end of the eurasiatic tethys similar permian deep water faunas are known from the phyllite unit of crete and from oman in the latter area partly above oceanic crust all these occurrences indicate the presence of a late paleozoic tethys ocean immediately north of gondwana

crystalline and sedimentary rocks from the scarps of the sicily sardinia trough and cornaglia terrace southwestern tyrrhenian sea italy paleogeographic and geodynamic implications abstract the petrographic and stratigraphic analysis of crystalline and sedimentary rocks dredged in the west sardinia channel southwestern tyrrhenian sea led to the careful stratigraphic and structural reconstruction of a lower miocene submerged orogenic belt previously analysed only on seismic sections the deformed units which include some flakes of the sardinia margin have a hercynian type crystalline basement of amphibolite facies sillimanite bearing metamorphic rocks intruded by granitoids ranging in composition from granite to tonalite this is quite different from the sardinia basement because of the peraluminous character of the plutonic rocks it can therefore be attributed to the generic kabylo calabrian domain which may extend far beyond the investigated area the crystalline basement is directly overlain by a thick lower miocene synorogenic sequence consisting of deep sea arkosic turbidites which probably accumulated in a foreland basin or in minor basins migrating on a shortening continental margin most of the rocks of the kabylo calabrian domain exhibit a common post hercynian structural and metamorphic evolution which can be attributed to a low grade tectono metamorphic event corresponding to low greenschist facies conditions this possibly took place during the early miocene as regards the geodynamic setting it should be pointed out that the penetrative structures and metamorphic reequilibration of the kabylo calabrian units seem to result from an intracontinental collision which contemporaneously affected the sardinia block leading to the formation of a crustal shear zone the early miocene age of the metamorphism and turbiditic sedimentation suggests that crustal shortening was probably connected with the drifting and rotational phases of the corsica sardinia microplate

permian cephalopod limestones oman mountains evidence for a permian seaway along the northern margin of gondwana abstract cephalopod limestones of middle permian middle guadalupian wordian stage age occur at the base of the hawasina nappes in the oman mountains they overlie mafic volcanic rocks are a few meters thick are interbedded locally with reef derived gravity flow deposits the cephalopod limestones are interpreted as a condensed sequence caused by a regional transgression on the arabian platform the ammonoid fauna is remarkably similar to that of the western mediterranean and timor suggesting an unrestricted faunal exchange in a permian seaway along the northern margin of gondwana where pelagic sediments were being deposited due to the uncertain provenance of the cimmerian microcontinents the width of this seaway must remain speculative

middle miocene early pliocene wedge top basins of nw sicily italy constraints for the tectonic evolution of a non conventional thrust belt affected by transpression the study of geological evolution of a multiphase orogenic belt is complex expecially when the tectonic events are superimposed in a coaxial fashion the sicilian fold and thrust belt represents an interesting case study as a non coaxial superimposition of structures is recognizable owing to large synkinematic clockwise rotations during each of two subsequent compressional events these rotations involved also the syntectonic basins that developed in the wedge top depozone this study aims to constrain the tectono depositional evolution of the nw sicily fold and thrust belt and the associated wedge top depozone between the middle miocene and the early pliocene integrated analyses of stratigraphic sedimentological and structural field data allow us to better constrain the transition between the two tectonic events the syntectonic basins developed during the first late serravallian early tortonian tectonic event were relatively wide and characterized by marine sedimentation the onset of the second latest tortonian transpressional event induced localized deformation into the wedge top depozone and the syntectonic successions were accommodated as basin fill in progressively narrower and laterally discontinuous basins bounded by transpressional structures the lateral correlation of the wedge top successions suggests a latest miocene regional palaeoslope with a present day wsw dip which fits well with the tectonic transport calculated for the early compressional event

boulder coastal deposits at favignana island rocky coast sicily italy litho structural and hydrodynamic control abstract boulders are frequently dislodged from rock platforms transported and deposited along coastal zones by high magnitude storm waves or tsunamis their size and shape are often controlled by the thickness of bedding planes as well as by high angle to bedding fracture network we investigate these processes along two coastal areas of favignana island by integrating geological data for 81 boulders 49 rupture surfaces called sockets and fracture orientation and spacing with four radiocarbon dates numerical hydrodynamic analysis and hindcast numerical simulation data boulders are scattered along the carbonate platform as isolated blocks or in small groups which form as a whole a discontinuous berm underwater surveys also highlight free boulders with sharp edges and sockets carved out in the rock platform boulders are composed of ruditic to arenitic size clastic carbonates their size ranges from 0 6 to 3 7 m 0 55 to 2 4 m and 0 2 to 1 m on the major a medium b and minor c axes respectively the highest value of mass estimation is 12 5 t almost all of boulders and sockets are characterized by a tabular or bladed shape the comparisons between a the fractures spacing and the length of a and b axes and b the frequency peaks of c axis with the recurrent thickness of beds measured along the coastal zone demonstrate the litho structural control in the size and shape of joint bounded boulders these comparisons together with the similarity between the shapes of the boulders and those of the sockets as well as between the lithology of boulders and the areas surrounding the sockets suggest that blocks originate by detachment from the platform edge thus the most common pre transport setting is the joint bounded scenario hydrodynamic equations estimate that the storm wave heights necessary to initiate the transport of blocks diverge from 2 m to 8 m for joint bounded boulders and from few tens of centimeters up to 11 m for submerged boulders the comparison between the wave heights at the breaking point of the coastal zones with the results of hydrodynamic equations shows that waves approaching the coastline are able to transport all surveyed boulders our data suggest that boulders have been transported by several storm events even in very recent times

incipient extension along the active convergent margin of nubia in sicily italy cefalu etna seismic zone 1 recent geodetic data are compatible with nne ssw tectonic extension at a rate of 5 mm yr in sicily southern italy within a broader region of net active compression along the nubian plate margin northern africa the structures that accommodate such extensional regime and its cause are still unknown from field structural surveys and seismological analyses the geometry kinematics structural architecture and seismic potential of an extensional seismic zone linking cefalu and mount etna in central eastern sicily are defined the zone includes high angle wnw striking normal and right lateral strike slip faults and subordinate north and nne striking strike slip faults either right or left lateral the occurrence of small discontinuous faults and the absence of related depressions and sedimentary basins suggest that the extensional regime is still in an incipient stage the ongoing seismic activity possibly reactivates preexisting faults instrumentally and historically recorded earthquakes are lower than about 6 in magnitude and destructive events are historically unknown since at least 1300 a d this apparent upper bound of earthquake magnitudes is consistent with the maximum magnitude values estimated from the length of the longest mapped faults and sources of seismic swarms which all together suggest a value between 6 and 6 5 as the maximum expected magnitude that can be proposed at the present stage of investigation for earthquakes in the study area lateral extension on preexisting faults and upwelling of melt mantle material beneath mount etna are considered viable processes to explain at least in part the active extensional tectonics along the cefalu etna seismic zone strike slip seismic faulting beneath mount etna may be part of a previously proposed diffuse transfer zone affecting northeastern sicily and including the tindari fault

the miocene costa giardini diatreme iblean mountains southern italy model for maar diatreme formation on a submerged carbonate platform in this paper we present a model for the growth of a maar diatreme complex in a shallow marine environment the miocene age costa giardini diatreme near sortino in the region of the iblei mountains of southern sicily has an outer tuff ring formed by the accumulation of debris flows and surge deposits during hydromagmatic eruptions vesicular lava clasts accretionary lapilli and bombs in the older ejecta indicate that initial eruptions were of gas rich magma abundant xenoliths in the upper late deposited beds of the ring suggest rapid magma ascent and deepening of the eruptive vent is shown by the change in slope of the country rock the interior of the diatreme contains nonbedded breccia composed of both volcanic and country rock clasts of variable size and amount the occurrence of bedded hyaloclastite breccia in an isolated outcrop in the middle lower part of the diatreme suggests subaqueous effusion at a low rate following the end of explosive activity intrusions of nonvesicular magma forming plugs and dikes occur on the western side of the diatreme and at the margins close to the contact between breccia deposits and country rock they indicate involvement of volatile poor magma possibly during late stages of activity we propose that initial hydromagmatic explosive activity occurred in a shallow marine environment and the ejecta created a rampart that isolated for a short time the inner crater from the surrounding marine environment this allowed explosive activity to draw down the water table in the vicinity of the vent and caused deepening of the explosive center a subsequent decrease in the effusion rate and cessation of explosive eruptions allowed the crater to refill with water at which time the hyaloclastite was deposited emplacement of dikes and plugs occurred nonexplosively while the breccia sediment was mostly still soft and unconsolidated locally forming peperites the sheltered low energy lagoon filled with marine limestones mixed with volcaniclastic material eroded from the surrounding ramparts ultimately lagoonal sediments accumulated in the crater until subsidence or erosion of the tuff ring caused a return to normal shallow marine conditions

evolution of the southern tyrrhenian slab tear and active tectonics along the western edge of the tyrrhenian subducted slab abstract the evolution of the southern tyrrhenian subduction has been possibly controlled by distinct episodes of slab break off as indicated by a critical review of the geological literature and by the analysis of purposely acquired multichannel seismic profiles within the proposed interpretation the first episode occurred from 8 5 to 4 0 ma and affected the segment of the slab located in the sardinia channel causing the abandonment of the adventure thrust front in western sicily the second episode occurred between 2 5 and 1 6 ma affecting the segment of slab located north of sicily and was preceeded by rifting in the strait of sicily the space and time location of these episodes appear controlled by discontinuities pre existing within the subducted african plate that trend at high angle to the advancing subduction front these discontinuities delimit segment of subducted slab that can be affected by slab break off and can act as wayouts for magma and mantle derived he the major of these discontinuities the malta escarpment has been reactivated in the quaternary as a trench perpendicular tear step faults ultimately the hierarchy in strength of these trench perpendicular features could have affected the timing and amount of trench retreat and backarc opening

sea level changes during the last 41 000 years in the outer shelf of the southern tyrrhenian sea evidence from benthic foraminifera and seismostratigraphic analysis abstract an integrated high resolution study based both on a seismostratigraphic approach and on a sedimentary core vib 10 collected in the outer shelf 127 m depth from the southern tyrrhenian sea gulf of termini sicily provides new data about climatic eustatic and paleoenvironmental changes during the last 41 000 years the results based on the interpretation of a seismic profile on benthic foraminifera assemblages and on 18o records allowed recognition of two drastic sea level falls during the last glacial maximum lgm and the younger dryas yd the short deglacial event between lgm and yd known as bolling allerod played an important role in the sea level rise that produced changes in benthic foraminiferal assemblages favoring the proliferation of shallow water species of the inner shelf after the younger dryas warmer climatic conditions were rapidly established climatic optimum as indicated by the decrease of 18o values the rapid sea level rise due to the input of fresh water from ice caps melting following the increase of earth s mean temperature is also indicated by the aggradational geometries of sedimentary layers observed in the seismic profile and by the increase of benthic foraminiferal species typical of the outer shelf

deep seated gravitational slope deformations in western sicily controlling factors triggering mechanisms and morphoevolutionary models abstract a study of deep seated gravitational slope deformation dsgsd phenomena affecting areas of various geological and geomorphological settings in western sicily is described western sicily is underlain by a thin skinned imbricate wedge of meso cenozoic carbonate and siliciclastic rocks that formed by the stacking of several thrust nappes over the iblean foreland locally the original thrust sheets are folded and cut by high angle faults large areas of western sicily now display high relief energy due to plio pleistocene block faulting and uplifting and the quaternary morphogenetic phases are characterised by incision thereby triggering widespread dsgsds to identify controlling factors and triggering causes and to develop reliable morphoevolutionary models for the dsgsds of western sicily a geomorphological study based on field surveys and aerial photography interpretations was performed previous geomorphological data relating to well known examples of dsgsds were reconsidered leading to remarkable revisions of the interpretative models in certain cases new data were subsequently collected enabling recognition of additional dsgsd phenomena the whole body of data involves a total of 27 dsgsds affecting areas in two specific geological settings 1 areas with flat thrust surfaces where differential settlements back tilting lateral spreads in competent rocks overlying marls and clays large topples and or block type slope movements may develop and 2 areas where deep rooted carbonate units come into lateral contact with clayey marly units along high angle faults where lateral spreads in brittle homogeneous rocks sinking and or rock flows may occur these dsgsd phenomena are associated with different evolutionary stages allowing a morphoevolutionary model to be defined for the two geological conditions for these two different morphoevolutionary models the following structural features play an important role in the development of dsgsds 1 where carbonate bodies overlie clayey marly rocks triggering of the dsgsds traces back to deformation of a ductile substratum that follows the exhumation of the flat thrust planes and the underlying clayey marly rocks due to block faulting and or stream incision and 2 where homogeneous carbonate rocks hundreds of metres thick crop out the dsgsds are triggered by very high relief energy and tensile stress that follow the combined actions of quaternary block faulting and stream deepening associated with differential erosion

odp leg 107 in the tyrrhenian sea insights into passive margin and back arc basin evolution leg 107 of the ocean drilling program drilled a west northwest east southeast transect of seven sites across the tyrrhenian sea the youngest of the sub basins of the mediterranean sea sites 654 653 652 and 656 document the rifting and subsidence of the sardinia passive continental margin on the upper margin site 654 we cored a classic transgressive sequence subaerial conglomerates overlain by oyster bearing sands overlain by marine marl comparison between the recovered lithologies and seismic reflection profiles suggests that the synrift sediments on the upper margin are tortonian late miocene to messinian latest miocene in age whereas synrift sediments on the lower margin are messinian to pliocene in age during the messinian desiccation of the mediterranean sites 654 and 653 now on the upper sardinian margin apparently occupied a basinal setting where they received nannoplankton bearing clays interbedded with laminated gypsum sites 656 and 652 now on the lower sardinia margin were apparently higher standing during the desiccation event their messinian facies are subaerial and lacustrine respectively we infer from these lines of evidence that tilting and subsidence occurred more than a million years earlier on the upper margin than on the lower margin such diachroneity can be interpreted in terms of migration of the zone of maximum extension above a rolling back subduction zone or in terms of extension of continental crust by shear along a deep detachment fault sites 655 651 and 650 were drilled into two small basalt floored basins of the central and eastern tyrrhenian emplacement of basaltic crust in the central tyrrhenian vavilov basin apparently began more than a million years before emplacement of basaltic crust in the eastern tyrrhenian marsili basin this observation is compatible with previous suggestions that the tyrrhenian has grown southeastward in response to rollback of the down going slab that currently dips northwestward under the toe of italy at the easternmost site high vesicularity of the basalt and benthic foram assemblages in the oldest sediments imply that the basalt erupted in water shallower than 2 500 m it has apparently subsequently subsided to its present depth of 4 100 m below sea level nearly three times as fast as normal subsidence of crust formed at a mid ocean ridge

timing and magnitude of rotations in the frontal thrust systems of southwestern sicily we report new paleomagnetic and anisotropy of magnetic susceptibility ams results from upper tortonian to middle pleistocene sediments which were deposited upon and adjacent to active thrust structures in southwestern sicily the data show that the plio pleistocene sediments from the belice and menfi basins covering the saccense shelf limestones underwent any internal shortening after the early pleistocene santernian as well as any net rotation sediments around this area which overlie basinal meso cenozoic successions record systematic rotations one upper tortonian site to the west is 30 counterclockwise rotated while to the east lower pliocene to middle lower pleistocene sites within the gela nappe domain show 25 to 56 clockwise cw rotations these data show that the ductile basinal sediments were bent and rotated around the rigid saccense carbonates during the thin skinned southward propagation of the orogenic front we document here that the coastal sediments from the southwestern gela nappe underwent both a post middle early pleistocene 30 cw rotation and a post middle pleistocene e w to ese wnw flattening revealed by ams our data then constrain to the late pleistocene holocene the age of the last shortening episode occurring in the southwestern gela nappe front pleistocene rotations of similar amount also characterize the sicanian domain implying that it was incorporated in the gela nappe wedge during the recentmost episodes of deformation this evidence allows us to better understand the very large up to 114 post mesozoic rotations reported by channell et al 1980 1990 for the sicanian limestones as related to both miocene or older deformational episodes and the plio pleistocene evolution of the gela nappe

late cenozoic subduction complex of sicily abstract besides remnants of hercynian deformations in the peloritani nappe and of pre oligocene alpine structures in the troiani nappe most compressive structures observed in the sicilian accretionary wedge result from the late cenozoic tortonian to present continental subduction of the apulia iblei block and are thus synchronous with distensive structures related to the opening of the tyrrhenian sea syntectonic deposits fill southward migrating foredeeps in a sequential fashion and the dating of these deposits helps to constrain the timing of deformation similarly plio quaternary sediments eroded from the accreted units rest on top of the allochthon in either compressive piggy back depressions or extensional basins the age and configuration of these overlap deposits constrain our reconstructions of the subsurface geometry of the underlying peri tyrrhenian detachment faults or s verging thrust faults post depositional erosion normal faulting and syntectonic filling of basins contribute to maintaining the critical taper of the prism whose geometry is continuously altered owing to frontal accretion underplating and isostatic uplift

paleomagnetically determined rotations in the western sicilian fold and thrust belt new paleomagnetic data from the west sicilian fold and thrust belt indicate large scale clockwise rotations during tectonic transport for the platform and seamount paleogeographic units of the fold and thrust belt panormide and trapanese units there is a general consistency in the magnitude of rotation along strike suggesting the existence of large coherent structural units for the panormide platform clockwise rotations in the range of 90 to 140 relative to the underlying iblean parautochthon are recorded along 125 km of outcrop strike in the case of the trapanese unit clockwise rotations in the range of 47 to 70 relative to iblei are recorded along about 90 km of outcrop strike intervening basinal paleogeographic units imerese and sicanian units show clockwise rotations of similar magnitude although few reliable data are available from these units palinspastic reconstruction of the thrust belt incorporating the rotations and arguments for the present orientation of the margins of the paleogeographic units implies that the panormide platform and trapanese seamounts were originally elongated more or less north south relative to the present orientation of iblei the two units apparently coalesced to the south and were discontinuous to the north they and their intervening basins were part of a passive continental margin which occupied a large part of the area that was subsequently rifted to form the tyrrhenian sea

astronomical dating of a tectonic rotation on sicily and consequences for the timing and extent of a middle pliocene deformation phase a detailed palaeomagnetic study of long and continuous middle pliocene sections from the caltanisetta basin on sicily reveals a differential clockwise rotation occurring around 3 21 ma the rotation appears to be a rapid event 80 000 100 000 years which suggests that the responsible tectonic processes also occur rapidly its timing corresponds closely to the transition from the trubi to the narbone formation at 3 19 ma this transition marks a major change in sedimentary environment on sicily and in calabria and it is coeval for instance with the onset of sapropel formation in the eastern mediterranean apparently it marks a synchronous and central eastern mediterranean wide event data from the oldest sediments overlying the tyrrhenian basement odp leg 107 suggest an acceleration in opening of the tyrrhenian sea during the middle pliocene we speculate that this acceleration is related to a transpressional event in the sicilian fold and thrust belt and extension which formed troughs in the foreland the strait of sicily thrust imbrication accompanying the transpressional event on sicily induced the middle pliocene clockwise rotation and resulted in shallowing of the caltanisetta basin causing the change in sedimentation regime characterised by the trubi narbone transition following this middle pliocene tectonic phase no rotation took place in the southern apennines calabria and sicily until the middle pleistocene 1 0 0 7 ma 1998 elsevier science b v all rights reserved

paleogeography and structure of the central mediterranean sicily and its offshore area abstract the geology of the mainland and offshore of sicily is illustrated by a few geologic sections and seismic profiles across the late cenozoic orogenic belt of central and western sicily and across the sardinia channel and sicily straits this belt is the result of several tectonic events deformation involved mainly the sedimentary cover of the old african continental margin characterized by a broad basinal domain flanked along its external southern margin by a shallow water carbonate platform attached to africa in the triassic compressional deformation started in the more internal basinal rock assemblages overlying a thinned crust the most important structural characteristic of the early phase of thrusting is the duplex pile forming the bulk of the chain in central western sicily the structure consists of a basal allochthon made up of permian to middle triassic layers an intermediate duplex wedge composed of competent mesozoic carbonates and a roof complex including upper mesozoic lower tertiary less competent rocks large scale clockwise rotation of the thrusts accompanied transpressional movements in the hinterland during the pliocene right oblique reverse faults modified the previous tectonic contacts between the allochthons in the hinterland zones contemporaneous south directed imbrications affected the southern external areas progressively incorporating foreland and piggyback basins development of the gela thrust system appears to be linked to the transpressional event its accretion is also related to contemporaneous underthrusting at deeper levels of mesozoic carbonate substratum the older buried thrust sheets were pushed up to the surface breaching the deformed tertiary cover of the gela ts northwards in the belt post messinian normal growth faults opened half graben whose sedimentary fill underwent structural inversion alternation of extension and compression tectonics characterizes the sicilian continental margin in the last million years

tectonics and seismicity of the tindari fault system southern italy crustal deformations at the transition between ongoing contractional and extensional domains located above the edge of a subducting slab 1 the tindari fault system southern tyrrhenian sea italy is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab onshore structural data an offshore seismic reflection profile and earthquake data are analyzed to constrain the present geometry of the tindari fault system and its tectonic evolution since neogene including the present seismicity results show that this zone of deformation consists of a broad nnw trending system of faults including sets of right lateral left lateral and extensional faults as well as early strike slip faults reworked under late extension earthquakes and other neotectonic data provide evidence that the tindari fault system is still active in the central and northern sectors and mostly accommodates extensional or right lateral transtensional displacements on a diffuse array of faults from these data a multiphase tectonic history is inferred including an early phase as a right lateral strike slip fault and a late extensional reworking under the influence of the subduction related processes which have led to the formation of the tyrrhenian back arc basin within the present regional geodynamic context the tindari fault system is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments these tectonic compartments relating to the complex processes of plate convergence occurring in the region the tindari fault system might also be included in an incipient oblique extensional transfer zone linking the ongoing contractional belts in the calabrian ionian and southern tyrrhenian compartments

a facies distribution model controlled by a tectonically inherited sea bottom topography in the carbonate rimmed shelf of the upper tithonian valanginian southern tethyan continental margin nw sicily italy the upper tithonian valanginian shallow water carbonates outcropping in the palermo mts nw sicily consist of several facies associations reflecting different depositional environments of a carbonate rimmed shelf pertaining to the southern tethyan continental margin the reconstructed depositional model based on the sedimentological features cyclic facies arrangement and biota distribution shows that a wide protected lagoon dominated by algae molluscs and scattered patch reefs was bordered landward by a tidal flat where stromatolitic algal mats were cyclically subaerial exposed and seaward by a marine sand belt and reef complex oolitic packstone grainstone lithofacies cyclically subjected to subaerial exposure suggests the occurrence of a barrier island located nearly to the lagoonal carbonate shoreline allowing the development of narrow embayments with restricted circulation in the outer platform the oolitic lithofacies of the marine sand belt pass landward into the protected lagoon where washover oolite sands occur and seaward into a high energy zone back reef apron gradually merging in the reef complex in the latter coral framestone occupied the inner sector reef flat while the facies association dominated by boundstone with ellipsactinia sp developed in the outer sectors reef wall adjacent to the fore reef and upper slope environments stratigraphic evidence associated with the recognized facies associations helped to reconstruct the geo tectonic setting of the carbonate platform where the distribution of the depositional facies along the shelf and their extension were influenced by the tectonically inherited sea bottom topography in a regime of extensional tectonics localized and thin succession of high energy prograding oolite sand belt depositional facies occupied structural highs footwall uplift while the largely diffused and thick low energy aggrading peritidal to lagoonal depositional facies developed in subsiding hanging wall the reef complex and the fore reef depositional facies exhibiting lateral migration and prograding geometries with clinoforms and downlap stratal terminations developed on a subsident stepped margin adjacent to a faulted shelf break this morphostructural setting can be comprised in a model where the tilted and faulted blocks inner platform and stepped margin outer platform paleo topography inherited from the rifting tectonics was the most important factor controlling the geometry and depositional architecture of a carbonate platform growing on the southern tethyan passive margin

using high resolution stratigraphy and structural analysis to constrain polyphase tectonics in wedge top basins inferences from the late tortonian scillato basin central northern sicily abstract the present paper aims to show both from a stratigraphic and structural points of view the main features of a wedge top syntectonic basin which evolved recording polyphase and non coaxial tectonics the study area is the scillato basin sb a roughly n s oriented structural depression located in the central northern sector of the sicililian maghrebides there an approximately 1300 m thick upper serravallian to upper tortonian succession of clastic units outcrops as a portion of the neogene syntectonic covers of the sicilian fold and thrust belt within the outcropping succession the upper tortonian terravecchia fm represents the main topic of this paper a multidisciplinary approach was carried out through an integration of sedimentology facies stratal pattern and structural analyses this was applied to the formation enabling one to recognize in the scillato basin a fining to coarsening upward succession deposited recording an early transgressive and a late regressive depositional stage in our model these two main depositional stages developed and are directly relatable to a two step structural evolution of the basin during the first step a nw se oriented structural depression existed enclosed between structural highs and accommodating the lower and middle portion of the upper tortonian succession subsequently during the second step the nw se depression was non coaxially deformed by superimposition of high angle transpressive faults many of which were se dipping developed in response to the upward propagation of structures enucleated at deeper structural levels this step was recorded in the basin by development of both depositional and structural interferences recognizable along the upper portion of the scillato basin succession a comparison between field data and deep geophysical data interpreted at the preliminary stage raises questions about the late miocene geological evolution of this sector of the sicilian chain including i the syn tectonic deposition of the terravecchia fm in the scillato basin clearly recorded the interference of two main and non coaxial tectonic events ii the younger of these two events has a clear tranpressional character and was active during the very late tortonian iii as also indicated by many authors in neighboring orogenic wedges the main control on the location geometry and depositional evolution of the scillato wedge top basin was carried out by compressional and transpressional structures developed at a deeper structural level their deformation propagated upward both into the shallow structural level and sedimentary covers therefore iv the late miocene structural scenario here depicted is not consistent either with the back arc related extension or with the late orogenic gravitational collapse models previously invoked by other authors with regard to this sector of the sicilian thrust belt

origin and deformation of the neogene recent maghrebian foredeep at the gela nappe se sicily se sicily contains one of the few exposures of orogenic foreland to the maghrebian apennine orogenic system in the central mediterranean here the african foreland is represented by the hyblean plateau adjacent to the frontal thrust structures of the maghrebian chain these structures include the disrupted foredeeps to earlier parts of the thrust system one of these the gela nappe is a major structure composed of late oligocene to early pliocene sediments emplaced onto pliocene pleistocene rocks of the buried foreland this paper presents a correlation of late miocene stratigraphic units between the foreland and the foredeep basin abrupt lithological and thickness variations of these units suggest that the foredeep basin was limited towards the foreland by normal faults in the hinterland these foredeep sediments lap back onto previously emplaced thrust sheets including the far travelled units of numidian flysch the precursor oligocene serravallian foredeep may also have been controlled by normal faulting compressional tectonics are reflected in folding and thrusting which post dates deposition of lower pliocene chalks trubi formation although minor folding and erosion preceded this unit larger thrusts repeat the basin stratigraphy and carry it out onto the adjacent foreland a minimum of 8 km shortening since messinian times can be demonstrated although a more realistic figure is c 25 km at a time averaged rate off 0 5cm a 1 the stratigraphic relationships on the foredeep sedimentary sequences may provide analogues for offshore areas of the thrust belt