foreland directed gravitational collapse along curved thrust fronts insights from a minor thrust related shear zone in the umbria marche belt central northern italy gravitational collapse occurs during the mature evolution of orogenic belts but its signature is difficult to discriminate in macroscopic structures from that of pre syn or late post orogenic extension so reliable mesoscopic examples are particularly useful a composite fabric developed along a lateral thrust ramp in the apennines reveals mesoscopic normal faults that truncate the thrust surface overprint the s fabric and merge downwards in a foreland directed splay leaving the thrust footwall undeformed these relationships indicate syn late thrusting extension which we interpret as induced by hanging wall gravitational collapse our study provides critical constraints for reconstructing the kinematic evolution of collapsing thrust fronts

a soft linkage between major seismogenic fault systems in the central southern apennines italy evidence from low magnitude seismicity abstract we investigate the transfer zone and linkage between divergent extensional seismogenic fault systems on the border amid the central and southern apennines central italy these regional nw se striking sets include large seismogenic sources that caused major historical earthquakes m w 7 the faults in the northern part of the study area dip to the southwest those in the southern part dip to the northeast the sw dipping system abruzzi apennines terminates with the aremogna cinque miglia source the ne dipping system southern apennines terminates with the boiano basin source to test whether the transfer zone model applies to the central southern apennines border we analyzed and relocated seismicity that occurred from 2007 to 2011 between the aremogna cinque miglia and boiano basin sources where we expect the transfer zone seismicity is made of independent events md the spatial distribution of seismicity the geometry and kinematics of active faulting in the region and the results from previous geophysical studies allow us to contend the existence of a transfer zone between these seismogenic normal fault systems our data also allow us to recognize the activity of such transfer along the central part of the ortona roccamonfina line we infer that reverse in dip polarity between the two normal fault systems could also result from the passage between the diverse tectonic units composing the border between central and southern apennines

positive inversion tectonics in foreland fold and thrust belts a reappraisal of the umbria marche northern apennines central italy by integrating geological and geophysical data abstract unraveling the tectonic style in the outer zones of fold and thrust belts is generally puzzling because the basement cover relationships are often hidden in the subsurface as in the outer northern apennines of italy this study aims to reconstruct the deep setting of the northern apennine foreland thrust belt by integrating surface structural geological and subsurface seismic reflection profile and well data corroborated by a gravity magnetic modeling a remarkable mountain ridge the umbria marche apennine ridge umar which corresponds to a prominent area of structural and topographic elevation characterizes the morphology of the northern apennines this mountain ridge is constituted by meso cenozoic carbonates involved in neogene compressive structures and is surrounded by wide exposures of foredeep deposits the basement cover relationships are poorly constrained and both thin and thick skinned tectonic styles have been applied the interpretation of subsurface data allowed recognizing a thick pre jurassic sedimentary sequence filling a late paleozoic triassic symmetric fault bounded extensional basin lying directly below the umar this deep rooted basin underwent positive inversion during the neogene compression and thrust fold development the reconstructed thick skinned inversion tectonic model is consistent with both the modest amount of shortening and the remarkable structural elevation of the umar the outcomes of this study reveal that prominent mountain ridges occurring in foreland thrust belts are most likely related to the deep rooted basement involved positive inversion of pre existing extensional basins

the arcuate shape of the umbria marche sabina apennines central italy abstract the umbria marche belt constitutes the most southern and external portion of the northern apennine arc typically convex to the northeast within this the central part the umbria marche sabina apennines is the most elevated and is characterized by a locally more pronounced curvature the umbria marche belt is a thrust belt built mainly by thrust faults affecting a multilayer sedimentary series characterized by levels with markedly different competence the main thrust the m sibillini thrust produced the tectonic superposition of the umbria marche sabina apennines over the most external units represented by the lazio abruzzi platform to the south and the marche abruzzi domain to the north farther north it joins the thrusts buried under the po plain the most important of the more internal thrusts is that of the valnerina the pronounced local curvature of the umbria marche sabina apennines may be due to accentuation of an original arcuate shape this accentuation is probably caused by differential displacement along the two main thrusts during the initial stage of the evolution of the belt late messinian early pliocene at that time this displacement was more important in the northern part where the thrust fronts show a nw se trend than in the southern portion where they are n s trending on account of the lazio abruzzi carbonate platform which perhaps represented a local obstacle to thrusting as for the initial curvature we think that this is determined by older discontinuities which controlled thrust development the final arcuate shape was not substantially changed during the subsequent compressional history of the belt early pliocene middle pliocene

understanding progressive arc and strike slip related rotations in curve shaped orogenic belts the case of the olevano antrodoco sibillini thrust northern apennines italy 1 we report on a paleomagnetic study of the southern sector of the olevano antrodoco sibillini oas thrust front which corresponds to the southern limb of the northern apennines italy orogenic salient a lively debate has developed regarding the oroclinal progressive arc versus non rotational nature of the oas which has been alternatively interpreted as a dextral strike slip fault dextral transpressive fault or frontal to oblique ramp that reactivated pre existing jurassic normal faults here we document the paleomagnetism integrated with biostratigraphic and structural data of 52 new sites from both the oas hanging wall and footwall on the basis of 39 retained sites we find a peculiar pattern of tectonic rotations along the oas thrust that evidences four rotational domains the thrust footwall is characterized by a southern domain that undergoes an approximately 30 counterclockwise rotation with respect to the stable foreland and an approximately non rotated domain the data from the hanging wall indicate the occurrence of a dextral strike slip component along the southern sector of the oas thrust supported by a strong clockwise rotation close to the ne sw lateral ramp which rapidly fades 1 km from the thrust front a slight but significant cw rotation observed in the remaining sites from the hanging wall confirms the progressive nature of the oas and its structural position as the southern limb of the northern apennines salient our detailed paleomagnetic study is crucial in discriminating between progressive arc and strike slip related components in the main curved orogenic front of the northern apennines

contrasting styles of fault reactivation in curved orogenic belts examples from the central apennines italy the geometry of the apennine fold and thrust belt has been strongly influenced by the original architecture of the adria paleomargin in the central apennines pre thrusting normal faults pre orogenic permian triassic jurassic and synorogenic neogene were reactivated with compressional kinematics during the neogene quaternary orogenesis we present a study of the control of preexisting extensional faults on thrust tectonics in the central apennines we describe positive inversion geometries of some salient fold and thrust structures from the central apennines setteporte the sabini mountains the sibillini mountains montagna dei fiori the gran sasso range maiella mountain and casoli bomba by integrating surface geological data and seismic line interpretation in these structures different styles of fault reactivation depend on their orientation with respect to the subsequent compressional ne sw trending stress field the nw se and wnw ese trending pre thrusting normal faults in the backlimbs of the anticlines were displaced and passively translated in the hanging wall blocks of the thrust planes thus exhibiting a classical shortcut geometry shortcut anticlines differently pre orogenic normal faults in the n s trending anticlines were reactivated in a transpressive deformational context as documented by the mainly dip slip and strike slip kinematics along the thrusts and back thrusts respectively reactivation anticlines the cases studied document differences in geometry in fold and thrust structures related to the trend of preexisting extensional faults showing that different reactivation geometries linked to the same inversion event can coexist at regional scale in curved fold and thrust belts the proposed inversion tectonic model and the resulting geometry of the fold and thrust belt could possibly be applied to analogous orogenic belts

analogue modeling of positive inversion tectonics along differently oriented pre thrusting normal faults an application to the central northern apennines of italy inversion tectonics represent a key process in many orogens worldwide the related mechanisms of fault reactivation and the effects of an articulated preshortening setting on thrust and fold development are still challenging questions modes and geometries of inversion have been the object of several analogue models in this work we analyzed the influence of an articulated high angle preexisting discontinuity in the development of thrusts using sandbox modeling the model geometry is based on the architecture of the major faults in the central northern apennines of italy where differently oriented mesozoic cenozoic inherited extensional structures are clearly detectable and display contrasting styles of positive inversion tectonics quartz sand is the analogue material adopted to model mesozoic cenozoic sedimentary successions and glass microbeads represent preexisting fault rocks the geometry of the segmented preexisting structure is composed of two segments with the same dip 60 one oblique and another orthogonal to the shortening direction our results show that different styles of positive inversion tectonics can coexist and that the obliquity angle between inherited structures and the shortening direction is a leading factor controlling the degree of inversion the oblique segment of the discontinuity exhibits a complete reactivation whereas along the orthogonal segment shortcut is the prevalent mechanism the oblique element moreover represents a cross strike discontinuity that guides the localization and curved geometry of the thrusts compartmentalizing the deformation our findings can be applied to fold and thrust belts characterized by the presence of cross strike discontinuities

the effects of pre existing normal faults on thrust ramp development an example from the northern apennines italy the umbria marche foreland fold and thrust belt in the northern apennines of italy provides excellent evidence to test the hypothesis of synsedimentary structural control on thrust ramp development this orogenic belt consists of platform and pelagic carbonates late triassic to miocene in age whose deposition was controlled by significant synsedimentary extension normal faulting mainly active from jurassic through late cretaceous paleogene time resulted in significant lateral thickness variability within the related stratigraphic sequences by late miocene time the sedimentary cover was detached from the underlying basement and was deformed by east verging folds and west dipping thrusts two restored balanced cross sections through the southernmost part of the belt show a coincidence between the early synsedimentary normal faults and the late thrust fault ramps these evidences suggest that synsedimentary tectonic structures such as faults and the related lithological lateral changes can be regarded as mechanically important controlling factors in the process of thrust ramp development during positive tectonic inversion processes

spinel from archean impact spherules abstract large meteorite impacts are recorded in distal fall deposits preserved in two early archean greenstone belt sequences 3 2 3 5 ga mapping stratigraphie and geochemistry studies have been used to identify at least four impact layers in the barberton greenstone belt of southern africa and one in the pilbara greenstone belt of western australia spherules that represent impact melt droplets distinguish these impact layers from associated tuffs spinel with unusual compositional traits occurs within spherules in two of these impact layers spinel is the only preserved primary phase and is found within up to 10 of the spherules in the best preserved layers some spherules contain up to 40 spinel which is often the only primary phase that crystallized within the spherules spinel morphologies include dendrites and skeletal octahedra typical of those found in high temperature melts spinel compositions are similar to those of cenozoic impacts including very high ni and ferric iron contents but the archean spinel is distinctive in being composed dominantly of the chalcophile elements fe ni cr and v this spinel is not metamorphic or metasomatic in origin closely associated komatiites in the underlying onverwacht group both fresh and highly altered have unaltered spinel with igneous compositions and morphologies quite distinct from the impact spinel characteristics of spinel preserved in these archean impact spherules suggest a rather complex series of steps following a large bolide impact initial high temperature reduction produced melt droplets some of which were immiscible silicate metal sulfide density differences allowed separation of some of these immiscible melts which subsequently evolved independently and formed spherules with highly variable chalcophile element contents oxidation during atmospheric reentry increased ni fe and fe 3 fe 2 in the chalcophile siderophile melts archean impact spinel has higher ni fe than cenozoic impact spinel though distinctly lower fe 3 fe 2 which probably reflects a substantially less oxidizing atmosphere during the archean the archean atmospheric oxidation may in fact be a transient phenomenon associated with a large impact into the terrestrial ocean resulting in very high atmospheric h 2 o h 2 bolide size is estimated to be 24 km in diameter based on the average diameter of 0 85 mm for the spinel bearing spherules this estimate is consistent with the observed ir fluence in spinel bearing impact layers of approximately 5 3 mg cm2 which would be produced by a 30 km diameter chondritic bolide

styles of positive inversion tectonics in the central apennines and in the adriatic foreland implications for the evolution of the apennine chain italy abstract integration of new field structural and geophysical data with existing information from the apennines chain in italy and its adjacent adriatic foreland indicates that the styles of positive inversion tectonics and the modes of interaction between the extensional and the subsequent compressive structures vary starting from the cretaceous the contractional deformation induced by the mainly north directed convergence of africa adria with respect to the european plate promoted the closure of various arms of the atlantic and the neo tethys oceans which opened in different times and with distinct orientations the mosaic of continental blocks carbonate platforms rift basins and oceanic domains with several geometries and orientations with respect to the axis of the subsequent compression and the resulting heterogeneities within the shallow sedimentary cover and the overall lithosphere strongly influenced both the structural evolution of the apennine orogenic belt and the intra continental deformation within the adriatic foreland field observations reveal that the steeply e and w dipping mesozoic cenozoic normal faults are systematically decapitated by sub horizontal or gently west dipping thrusts propagating with short cut trajectories pre thrusting normal faults were commonly deformed by later thrusts but little evidence seems to support their entire reactivation as high angle reverse faults this suggests that these shallow and steeply dipping discontinuities were not suitable to be reutilized by the superficial thin skinned thrust faults propagating within the sedimentary cover in contrast presumably late paleozoic and mesozoic w dipping normal faults appear moderately reactivated in the adriatic foreland and strong positive inversion tectonics affect the deeper and buried structural levels of the apennine chain within the latter the syn rift sediments in the hangingwall blocks of the fault bounded basins were totally extruded and generated the strong uplift of the thinned adria continental crust finally the contrasting styles of interactions of the pre existing normal faults with later thrusts i e passive truncation or positive reactivation strictly result from the different evolution of the apennine chain and the combined thin and thick skinned modes of deformation of the stretched lithosphere of the adria plate

behaviour of minor arcuate shapes hosted in curved fold and thrust belts an example from the northern apennines italy s satolli et al minor arcs in curved fold and thrust belts arcuate fold and thrust belts have been extensively studied in the literature less attention however has been paid to the characteristics of local scale arcuate structures meaning 5 10 km long fold or thrust traces that display map view curvature nevertheless detailed investigation of small arcuate structures hosted in major arcs can contribute to understanding the pervasiveness of deformation mechanisms we performed a combined geological and palaeomagnetic study on 21 sites from a c 60 km 2 area in the northern apennines in order to analyse minor arcs at a kilometric scale as evidenced by the geological and structural analysis performed on the 21 sites the fold axial trend changes from n s to nw se in the study area the comparison with palaeomagnetic results shows the lack of correlation between vertical axis rotations and fold axial trends as a consequence the minor arcuate shapes of thrusts and related folds are interpreted as mostly primary features inherited from the geometry of the palaeomargin represented by pre orogenic faults according to a context of inversion tectonics

magnetic fabric in carbonatic rocks from thrust shear zones a study from the northern apennines italy abstract we present the results of an integrated structural and anisotropy of magnetic susceptibility ams investigation in calcareous and marly rocks from thrust shear zones a total of 17 sites from six localities along the frontal and oblique ramp of the olevano antrodoco sibillini thrust and back thrust northern apennines italy were studied to investigate both magnetic fabric and structural characteristics of cretaceous to neogene calcareous and marly rocks in most of the sites ams is controlled by the paramagnetic minerals prevailingly phyllosilicates with minor contribution of ferromagnetic sensu latu ones structural analysis shows the presence of sc and s tectonites associated to predominant simple and pure shear respectively the combination of density diagrams and cluster analysis allowed discriminating the contributions of sedimentary and tectonic processes to the bulk magnetic fabric six different subfabrics were distinguished related to the structural data and associated to deformation stages and regimes a sedimentary fabric b intersection lineation c magnetic foliation parallel to s planes with k1 parallel to the s c intersection d k1 moving toward the slip vector e magnetic foliation parallel either to the s or the c planes with k1 parallel to the slip vector or the transport direction f k1 parallel to extensional planes intersection the magnetic foliation has a double tendency to parallelize to pressure solution cleavage s and shear planes c while the magnetic lineation tends to progressively align with the slip vector except for pure shear dominated sites at less than 15 20 cm from the thrust where it aligns with the transport direction the magnetic fabric is dominated by simple shear deformation the protocol applied for ams analysis shows a great potential to unravel mixed sedimentary and or tectonic features in magnetic fabrics ams can be considered as a useful tool in unravelling the variation of simple pure shear deformation regime in shear zones

half graben rupture geometry of the 30 october 2016 mw 6 6 mt vettore mt bove earthquake central italy

analysis of thrust shear zones in curve shaped belts deformation mode and timing of the olevano antrodoco sibillini thrust central northern apennines of italy abstract this work reports the results of our analysis of the brittle ductile shear zone associated with the olevano antrodoco sibillini oas curved shape thrust in the central northern apennines of italy its southern sector is characterized by nnw sse trending footwall anticlines which also affect the oas thrust surface s tectonites in the nne ssw trending sector are crenulated by conjugate extensional surfaces extensional crenulation cleavage the nw se trending segment of the oas thrust is characterized by sc tectonites developed along the thrust related shear zone both the sc and s tectonites are consistent with a top to the n60 70 e direction of tectonic transport the sc tectonites are associated with a simple shear dominated deformation wn 0 86 0 98 on the other hand the s tectonites and their related extensional shear planes document two stages of strain i sub simple shear wn 0 34 0 50 related to oas thrusting contemporaneous to growing incipient footwall anticlines and ii pure shear dominated deformation wn 0 17 0 00 subsequent to the oas thrusting and caused by the definitive growth of footwall anticlines within an in sequence deformation context the present study proposes the analysis of shear zones to i discriminate in sequence against out of sequence evolution and ii use as a tool to constrain the modes and timing of the curved belt s development

seismic modelling of outcrop carbonate systems an application to the cretaceous platform to basin system of the maiella mountain central apennines italy

pop up structure in massive carbonate hosted fold and thrust belt insight from field mapping and 2d kinematic model in the central apennines abstract fold and thrust belts are characterized by the occurrence of foreland verging thrusts and antithetic backthrust which develop in the hangingwall of thrust sheets both thrust and backthrust bound the so called pop up structure which is a deformed zone characterized by thrust and backthrust related anticlines pop up structures mainly develop in fold and thrust belts characterized by a multilayered sedimentary sequence consisting of limestones marls and shales deformed above a weak decollement such as evaporites however in this work we combine field mapping stratigraphic constrains and structural analysis with 2d kinematic forward modeling to document a pop up structure developed within limestones dolostones deformed above a strong decollement consisting of dolostones in the central apennines italy in particular we describe a sw verging anticline and a ne verging anticline in the sw and ne margin of the serra lunga ridge respectively such folds were generated by a ne dipping backthrust and by sw dipping forethrust respectively therefore we suggest that the serra lunga ridge represents a pop up structure showing geometries similar to other pop up structures observed within fold and thrust belts characterized by a multilayered sedimentary sequence in addition backlimb tilting of backthrust related anticlines generates the forelandward dipping monoclines observed within thrust sheets in the central apennines and in several fold and thrust belts worldwide

multi phase reactivations and inversions of paleozoic mesozoic extensional basins during the wilson cycle case studies from the north sea uk and the northern apennines italy

from mesozoic rifting to apennine orogeny the gran sasso range italy the apennines are a low temperature accretionary prism generated by the west directed subduction of the adriatic ionian plate whose structural origin is still to be fully understood the highest and best exposed seg ment of the apennines the gran sasso range is here documented to unravel the tectonic history of the northern tip of gondwana it is located along a ne verging salient of thrust sheets decoupling the sedimentary cover of the subducting adriatic lithosphere field mapping and structural analysis along the e w trending left lateral transpressive segment of the salient highlight the interplay of the inherited mesozoic passive margin stratigraph ic and tectonic framework with the neogene contraction the rheological differences between the massive carbonate platform and the well bedded turbiditic and pelagic limestones determined along strike undulations of the thrusts geometries and fold styles during shortening heterogeneities are due to inherited syn and post rift mesozoic tectonics the gran sasso overturned anticline shows a backlimb anomalously tilted toward the foreland and we infer this dip as being related to a deeper back thrust of a triangle zone the pinching out of the foredeep sequence on the growth anticline forelimb dates the contractional phases of the region to the late messinian from the late pliocene to present the area has been uplifted and extended about 2 km by oblique normal faults cross cutting the accretionary prism some of them are seismically active as shown by the 2009 mw 6 3 l aquila earthquake

formation of melt droplets melt fragments and accretionary impact lapilli during a hypervelocity impact abstract we present a model that describes the formation of melt droplets melt fragments and accretionary impact lapilli during a hypervelocity impact using the isale hydrocode coupled to the aneos equation of state for silica we create high resolution two dimensional impact models to track the motion of impact ejecta we then estimate the size of the ejecta products using simple analytical expressions and information derived from our hydrocode models ultimately our model makes predictions of how the size of the ejecta products depends on impactor size impact velocity and ejection velocity in general we find that larger impactor sizes result in larger ejecta products and higher ejection velocities result in smaller ejecta product sizes we find that a 10 km diameter impactor striking at a velocity of 20 km s creates millimeter scale melt droplets comparable to the melt droplets found in the chicxulub ejecta curtain layer our model also predicts that melt droplets melt fragments and accretionary impact lapilli should be found together in well preserved ejecta curtain layers and that all three ejecta products can form even on airless bodies that lack significant volatile content this prediction agrees with observations of ejecta from the sudbury and chicxulub impacts as well as the presence of accretionary impact lapilli in lunar breccia

test of the frictional reactivation theory for faults and validity of fault slip analysis the notion that slip on faults is controlled by the balance between resolved shear stress and the magnitude of frictional resistance is examined in the light of the published orientations of ancient faults and slip lineations by compiling data from more than 1500 faults used in 228 stress analyses we observe that natural fault planes as well as lineations formed by fault slip display characteristic patterns of preferred orientation when rotated into the reference frame defined by the principal stress axes these patterns vary systematically according to the relative magnitudes of principal stresses determined by fault slip analysis furthermore these patterns are strikingly similar to those predicted by a frictional model for fault reactivation in which the potential for slip is equated to the ratio of the components of shear stress and normal stress on the fault plane our findings therefore make a compelling case for the concept of frictional slip tendency for the prediction of fault reactivation and lend support to the validity of fault slip methods for paleostress analysis

how the structural architecture of the eurasian continental margin affects the structure seismicity and topography of the south central taiwan fold and thrust belt studies of mountain belts worldwide show that along strike changes are common in their foreland fold and thrust belts these are typically caused by processes related to fault reactivation and or fault focusing along changes in sedimentary sequences the study of active orogens like taiwan can also provide insights into how these processes influence transient features such as seismicity and topography in this paper we trace regional scale features from the eurasian continental margin in the taiwan strait into the south central taiwan fold and thrust belt we then present newly mapped surface geology p wave velocity maps and sections seismicity and topography data to test the hypothesis of whether or not these regional scale features of the margin are contributing to along strike changes in structural style and the distribution of seismicity and topography in this part of the taiwan fold and thrust belt these data show that the most important along strike change takes place at the eastward prolongation of the upper part of the margins necking zone where there is a causal link between fault reactivation involvement of basement in the thrusting concentration of seismicity and the formation of high topography on the area correlated with the necking zone the strike slip reactivation of east northeast striking extensional faults is causing sigmoidal offset of structures and topography along two main zones here basement is not involved in the thrusting there is weak focusing of seismicity and localized development of topography we also show that there are important differences in structure seismicity and topography between the margins shelf and its necking zone

stress analysis post orogenic extension and 3 01 ga gold mineralisation in the barberton greenstone belt south africa gold deposits in the barberton greenstone belt bgb have formed along a common network of brittle ductile shear zones that developed during extension and emplacement of felsic porphyry dykes at 3015 ma at a deposit scale mineralised shears occur in en echelon arrays distributed as riedel p and anti riedel shears with envelopes that connect groups of mine workings along nnw ene ne and ese trends the dip of the mineralised shear envelopes is generally moderate to steep 50 80 the existence of the directional alignment of gold deposits at the scale of the greenstone belt has been demonstrated with fry analysis stress inversion for mineralised shear zones from workings near 28 mines using a bingham axial distribution and an optimized right dihedron approach provide near identical results with 1 vertical and 3 horizontal nw the stress regime is generally radial extensional or pure extensional at the scale of the greenstone belt the mineralised shear envelopes comprise two sets of near orthogonal trends positioned symmetrically with respect the measured far field stress 1 a nw and ne trending pair with the latter accommodating pure normal slip and the former both dextral or sinistral strike slip and 2 a nnw and ese trending pair accommodating dextral transtensional and sinistral transtensional movements respectively the fact that all mineralised shears developed systematically in response to a similar far field stress suggests that mineralisation formed during a single tectonic stage pb pb ages of 3017 1 17 8 ma and 3008 8 16 ma from a syn mineralisation porphyry dyke near golden quarry indicates gold deposition at 3015 ma i e 85 ma after the craton had stabilised older porphyry dykes intruded near sheba and consort mines have been dated at 3100 ma and 3260 ma respectively and provide a minimum and maximum age constraint on accretionary deformation in the area we propose that the main phase of gold enrichment in the bgb occurred after tectonic and thermal stabilisation of the crust at a time the craton was acting as a stable terrane mineralised brittle ductile shear zones allowed ingress of deeply sourced fluids during cratonic extension mine camps display a cluster spacing of 12 km which suggests a regular distribution of controlling shears possibly as a function of the elastic rigidity of the lithosphere rather than linking mineralisation to orogenic processes during greenstone belt accretion we link gold mineralisation to the opening of fault bounded intracratonic basins including the pongola and witwatersrand basins and concomitant igneous activity

tectonic inversion and basement buttressing an example from the central appalachian blue ridge province abstract the structural geometry of the central appalachian blue ridge province is primarily the result of paleozoic contractional deformation however the tye river fault zone in the western blue ridge of central virginia preserves an extensional map pattern these ene wsw striking faults place neoproterozoic to early cambrian volcanic and sedimentary rocks over grenvillian granitic basement detailed mapping cross section restoration and balancing reveals partially inverted faults original half grabens and significantly thicker cover units on hanging walls the orientation and geometry of the tye river fault zone as well as the thickness changes in the cover rocks are inconsistent with extensional reactivation of paleozoic reverse faults during mesozoic rifting the extrusion and deposition of cover rocks was contemporaneous with normal displacement on the tye river fault zone and the formation of rift basins recording 5 crustal extension faults were reactivated as paleozoic contractional structures but an extensional map pattern is generally still preserved regional shortening of 10 20 was accomplished primarily by folding of the cover rocks rather than by reactivation of older faults the basement formed a rigid buttress that controlled the geometry of folding in the cover sequence

discovery of extraterrestrial component carrier phases in archean spherule layers implications for estimation of archean bolide sizes in the barberton greenstone belt bgb of south africa four distinct spherule horizons s1 s4 with ages between ca 3 5 and 3 2 ga are among the oldest records of large asteroid impacts on earth spherules in these layers are interpreted as molten impact ejecta condensation products from impact plumes or impact ejecta melted during atmospheric reentry past research has shown that some spherule layer samples from the bgb carry ultrahigh abundances of siderophile elements including platinum group elements pges in some cases as much as four times the chondritic abundances inferences for very large projectile sizes responsible for these impact layers have been made on the strength of these data drilling by the international continental scientific drilling program has yielded 4 new spherule layer intersections in a 22 cm long core segment scanning electron microscopy energy dispersive x ray spectrometry at high spatial resolution identified local areas of pge enrichment with ni rich chromium spinel ni cr spinel clusters they are associated with pge rich metal alloy and sulfarsenide phases 600 1400 nm in size the metal alloys are interpreted as primary objects that formed during the impact process pge sulfarsenides are the result of secondary alteration by s and as rich fluids thus a micronugget effect caused by pge phases and ni cr spinel is responsible for the anomalously high extraterrestrial component in some spherule layer samples this heterogeneous incorporation of meteoritic components due to primary heterogeneous fallout from the vapor plume must be taken into consideration in any attempt to estimate the global fallout of extraterrestrial components and thus to constrain projectile sizes

coalescence of fault bend and fault propagation folding in curved thrust systems an insight from the central apennines italy the coalescence and spatial variability of different thrust related folding mechanisms involving the same mechanical multilayer along a curved thrust system are documented in this study the field based analysis of thrust related folds spectacularly exposed in the gran sasso thrust system central apennines of italy allowed us to reconstruct the interference fold pattern between fault bend and fault propagation folding these two thrust related folding mechanisms exhibit spatial variability along the differently oriented ramps of the curved gran sasso thrust system passing from one style to the other their selective development is controlled by contrasting styles of compressional normal fault reactivation related to positive tectonic inversion fault bend and fault propagation folding interact with a characteristic interference fold pattern in the salient apex zone of the curved thrust system due to their synchronous in sequence growth this interference fold pattern might be helpful and predictive when reconstructing lateral variations in different thrust related folds in similar subaerial or submarine thrust belts

coexistence of fault propagation and fault bend folding in curve shaped foreland fold and thrust belts examples from the northern apennines italy terra nova 24 396 406 2012 abstract fault bend and fault propagation folds have unique profiles in foreland fold and thrust belts that are caused by different fault related folding models and controlled by the mechanical characteristic of the multilayer and or by reactivation of normal faults in a positive inversion tectonics context in this work nne ssw and nw se trending anticlines related to the neogene curve shaped olevano antrodoco sibillini thrust northern apennines italy are investigated to reconstruct fault related folding mechanisms geological and structural analysis allows us to interpret the nne ssw trending anticlines as fault bend reactivation folds and the nw se trending anticlines as fault propagation shortcut anticlines the coexistence of fault bend and fault propagation folding processes involving the same multi layered succession in different arms of a curve shaped thrust is explained in an inversion tectonics context this along strike variation of different folding mechanisms might be recognised in similar curve shaped orogenic thrust belts controlled by structural inheritance

understanding sibumasu in the context of ribbon continents abstract well described ribbon continent collision belts and modern examples with 2d seismic coverage particularly zealandia provide analogues for the permo triassic development of sibumasu two key parameters for the ribbon continents are their width and how rifting developed which in turn impact the structural metamorphic igneous and stratigraphic development of ribbon continents in ways that make them significantly different from the collisional development of major continents key characteristics of the tectonics of sibumasu are 1 a tendency towards basin inversion during the late triassic and possibly early jurassic and mixed thick skinned and thin skinned style deformation 2 extensional collapse around 215 ma is an important feature of sibumasu particularly in northern thailand and probably other areas too 3 slab delamination and extension related decompression melting were probably important mechanisms for generating granites in addition to crustal thickening 4 metamorphism is relatively high temperature lower pressure

differences and similarities between the central and the southern apennines italy examining the gran sasso versus the matese frosolone salients using paleomagnetic geological and structural data 1 the apennines consists of the following two major first order arcuate features the northern apennines arc and the southern apennines calabrian arc separated by the sangro volturno line in this paper we compare and discuss these major arcs which are characterized by several differences these are mainly related to differences in paleogeographic domains stratigraphic successions structural setting and geodynamic evolution we describe with particular emphasis the following two main salients the gran sasso range and the matese frosolone mountains geographically belonging to the central and the southern apennines respectively we analyze existing geological structural and paleomagnetic information from both salients and provide new paleomagnetic and magnetic anisotropy data for eight messianian tortonian sites from the matese frosolone mountains the aim of the work is to reconstruct the tortonian quaternary kinematic evolution of the central apennines which represents the junction zone between the northern apennines arc and the southern apennines calabrian arc furthermore we propose to use the different style of paleomagnetic rotations in arcuate shapes as a tool to discriminate if structures located in the central apennines geologically belong to the northern apennines arc or to the southern apennines calabrian arc finally the results of this study allowed us to interpret the sangro volturno line as an oblique ramp of the pliocene quaternary frontal thrusts

revitalising exploration and re development of deep carbonate targets in the southern apennines thrust belt southern italy reappraising vintage data with modern approaches

macro and meso scale structural criteria for identifying pre thrusting normal faults within foreland fold and thrust belts insights from the central northern apennines italy

early orogenic normal faults and their reactivation during thrust belt evolution the gubbio fault case study umbria marche apennines italy foreland early orogenic and hinterland late orogenic extensional domains have been widely documented in the northern apennines where they are synchronous with contraction in the active part of the fold and thrust belt the progressive eastward migration of the contractional front and the associated hinterland extensional field implies that early orogenic extensional structures developed in the foreland domains may experience reactivation inversion we present new field data integrated with seismic evidence from the gubbio normal fault a 22 km long presently active fault showing a evidence for early orogenic extension since the lower miocene time b successive positive inversion during the upper miocene contraction and c renewed late orogenic extension during the quaternary age field data allowed two systems of mesoscale normal faults respectively interpreted as early and late orogenic structures to be recognised stress fields associated with contractional and early late orogenic extensional tectonic regimes are characterised by an overall coaxiality with directions of compression and tension consistently aligned ne sw the symmetry between the successive deformation stages is interpreted as a likely cause for the repeated reactivation of the gubbio fault since the miocene our analysis in the gubbio area shows that normal faults play a key role during the evolution of a fold and thrust belt from the early orogenic stages when they influence the geometry and evolution of foredeep basins to the late orogenic stages when quaternary activity due to extension reactivation controls the evolution of the intramountain basins

lower plate geometry controlling the development of a thrust top basin the tectonosedimentary evolution of the ofanto basin southern apennines the ofanto basin is a pliocene pleistocene thrust top basin that formed with an unusual east west orientation along the frontal part of the southern apennine allochthon during the latest stages of tectonic transport its tectonic and sedimentary evolution was studied integrating field surveys biostratigraphic analyses and the interpretation of a large seismic grid well data and seismic interpretation indicate that a large east west trending normal fault underlies the northern margin of the basin displacing the apulian carbonates that form the foreland and the footwall of the southern apennine allochthon in our reconstruction the ofanto basin formed at the rear of the bulge caused by buttressing of the southern apennine allochthon against this normal fault in a second stage of contraction the footwall of the southern apennine allochthon was involved in deformation with a different trend from the normal faulting and buttressing this caused eastward tilting of the basin and broad folding around its eastern termination good stratigraphic constraints permit the age of buttressing to be defined as early pliocene and that of the shortening in the apulian carbonates as early pleistocene this study highlights the importance of early orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges supplementary material a 3d reconstruction of the base of the pliocene deposits of the ofanto basin based on seismic interpretation is available at www geolsoc org uk sup18559

testing different tectonic models for the source of the mw 6 5 30 october 2016 norcia earthquake central italy a youthful normal fault or negative inversion of an old thrust

early archean silicate spherules of probable impact origin south africa and western australia layers of sand sized silicate spherules in 3 2 to 3 5 ga archean greenstone belts in south africa and western australia formed by the accumulation of quenched liquid silicate droplets having primary compositions resembling those of immediately underlying rock sequences the layers and particles appear to be unrelated to volcanic activity and we suggest that both occurrences may represent melt droplets formed during meteorite or comet impacts if so these spherules are the oldest known terrestrial impact products if these objects are representative of a larger population of early archean impact features it may be possible to directly estimate the meteorite flux on the early archean earth

paleomagnetism of the gran sasso range salient central apennines italy pattern of orogenic rotations due to translation of a massive carbonate indenter 1 we report on the paleomagnetism 39 new sites of gran sasso an indenter controlled salient of the external central apennines formed by two orthogonal limbs we find that gran sasso is a complex salient paleomagnetically corresponding to neither a nonrotating nor an oroclinal end member data from the core of the arc show that the indenter itself did not undergo any rotation conversely rotations of variable magnitude and sign are observed along the curve shaped thrust fronts rotations are virtually absent at both end points of the arc moving toward the apex progressively greater counterclockwise ccw and clockwise cw rotations occur along the e w and n s fronts respectively the rotations increase continuously and more than linearly reaching their maximum values 80 ccw and 50 cw around the apex here the more strongly ccw and cw rotated fronts are separated by a domain characterized by local block rotations the inequality between the maximum ccw and cw rotation values is likely a consequence of the asymmetry of the indenter displacement direction n70 e with respect to the preorogenic trends of its margins e w and n s from an oroclinal point of view the fronts close to the end points virtually define a nonrotating arc while the pattern around the apex is similar to that of an orocline we conclude that close to end points nonrotational thrusting normal to the indenter margins occurred while in the vicinity of the apex the peritidal carbonates acted as an ice breaker pushing apart and strongly rotating the weaker multilayer located ahead

investigating fault reactivation during multiple tectonic inversions through mechanical and numerical modeling an application to the central northern apennines of italy abstract within inversion tectonic contexts the reactivation of pre existing discontinuities depends upon many structural stratigraphic and mechanical factors among these a fundamental aspect is represented by the orientation and attitude of pre existing discontinuities with respect to the new stress field the aim of this work is to evaluate the stress regimes and the mechanical conditions that controlled the reactivation of segmented pre thrusting normal faults in the central northern apennines of italy these faults were involved both in positive and negative inversion tectonic events during tertiary quaternary times mechanical slip tendency analysis and numerical using coulomb 3 3 software models allowed us to reconstruct a 3d stress field for both inversion events and to evaluate the effect of many parameters orientation of faults fault dip angle and mechanical parameters on fault reactivation our results highlighted that the orientation of pre existing faults with respect to the stress axes represents the main factor controlling inversion tectonic phenomena where other mechanical and geometric variables exert a subordinate role the models well reproduce the neogene quaternary deformation history reconstructed from detailed geological and structural analyses for the central northern apennines of italy and could be applied to other regions that have experienced inversion tectonic processes

facies character and depositional architecture of hydrothermal travertine slope aprons pleistocene acquasanta terme central italy abstract hydrothermal travertines develop various depositional geometries from tabular to high relief mounds or aprons with steep slopes under the control of local topography location and geometry of the vents fault activity hydrology water physico chemical properties rates of thermal water flow and carbonate precipitation rates this study focuses on two pleistocene tens of metres thick travertine slope aprons accumulated on fluvial terraces in the tronto river valley acquasanta terme central italy to investigate their facies character geochemical signature porosity and evolution of the depositional geometry through time the two travertine aprons consist of four aggradational progradational units vertically and laterally stacked with onlap and downlap stratal terminations separated by erosional unconformities produced by events of non deposition and erosion due to temporary interruptions of vent activity shifts of the vent location and or deviation of the flow directions the travertine units include various depositional environments 1 smooth slope 2 terraced slope with metre scale sub horizontal pools separated by rounded rims and vertical walls and 3 sub horizontal tens of metres wide ponds smooth slope clinoforms are made of centimetre to decimetre thick layers of crystalline dendrite cementstone laminated boundstone and radial coated grain grainstone precipitated by fast flowing water on inclined substrates rims and walls of terraced slopes are built by crystalline dendrites and laminated boundstone sub horizontal layers of terrace pools and ponds consist of facies precipitated by slow flowing to standing water clotted peloidal micrite dendrite coated bubble boundstone raft rudstone associated with radial coated grains and laminated boundstone carbonate coated reeds occur in distal ponds adjacent to toe of slopes or overlie packstone rudstone with travertine intraclasts and substrate extraclasts marking events of subaerial exposure and erosion travertine facies porosity and permeability range from 4 to 21 and 0 03 to 669 md respectively showing no direct correlation stable isotope values 13 c 5 7 9 3 18 o 9 6 to 12 2 are similar to other travertines precipitated by thermal water in central italy this study identifies the centimetre scale travertine facies variability linking it to the environment of deposition and to the depositional geometry of travertine units affected by the substrate topography and lateral shifts of the active springs despite the different scale and facies composition the geometry of aggradational progradational units of travertine aprons might resemble marine flat topped high relief carbonate platforms travertine units in the subsurface if present with sizes that can be seismically resolved might be wrongly interpreted as carbonate platforms with steep slopes without a detailed facies analysis

staircase fractures in microbialites and the role of lamination related mechanical anisotropy the example of the acquasanta terme travertine deposits central italy this study describes a peculiar yet common type of fracture showing a staircase trajectory which forms in rocks with moderately weak planar anisotropies the staircase fracture trajectory is given by alternating fracture segments oriented parallel to lap or at an angle ramp with respect to the lamination layering the analyses has been accomplished on travertines which are continental microbial hydrothermal deposits having a typical poorly stratified yet strongly laminated texture in these rocks porosity and permeability have a high across lamination variability and are mostly controlled by an interconnected and locally corroded array of permeable layers fractures and faults structural analysis integrated with analytical modeling provided a conceptual model of staircase fracture localization as a function of the travertine lamination dip lamination parallel fracture segments localize within the porous laminae mostly at the interface with tight laminae ramp type fracture segments cut the lamination connecting lamination parallel segments two types of staircase fracture can be modeled the first group develops in subhorizontal to gently dipping deposits lamination dip 30 and corresponds to high energy environments major discoveries of hydrocarbon have been recently made in continental lacustrine microbial carbonates in the brazilian south atlantic margin some of which exhibit a texture similar to those usually observed in travertines understanding of the lacustrine carbonates is still at an early stage given that in modern rift settings vent related thermal travertine and nonthermal tufa carbonates are a major component the proposed conceptual model of staircase fracture localization contributes to the preparation of a model for the potential occurrence of high permeability pathways in hydrocarbon and geothermal microbial reservoirs

push up inversion structures v fault bend reactivation anticlines along oblique thrust ramps examples from the apennines fold and thrust belt italy the study of inversion structures in fold and thrust belts that originated as extensional faults is valuable for the development of geometric and kinematic models that are helpful in unravelling the structural style and for detecting structural hydrocarbon traps we document push up inversion structures versus fault bend reactivation anticlines occurring along oblique thrust ramps by examining examples of buried apulian structures in the central southern apennines and outcropping thrust related folds in the central northern apennines of italy the different geometric features between push up inversion structures and fault bend reactivation anticlines are functionally controlled by the mechanical characteristics of the involved sedimentary multilayer the original architecture of the former extensional basin and the amount of thrust displacement the recognition of such inversion structures is important in understanding the anatomy and structural style of foreland fold and thrust belts in addition their identification is critical in interpreting the geometry and types of structural traps that may be expected along oblique thrust ramps this study reveals that push up inversion structures and fault bend reactivation anticlines could coexist along oblique thrust ramps within a curved thrust system and may be detected among analogous foreland thrust belts that include inherited extensional basins

3d structural modeling and restoration of the apennine maghrebian chain in sicily application for non cylindrical fold and thrust belts abstract thirteen seismic reflection profiles and field observations have been used to build a three dimensional watertight geological model of the sub surface architecture of the trapanese carbonate platform unit of the apennine maghrebian chain in the mt kumeta and mt rocca busambra nw sicily italy either a single step or a two step thrust fault deformation model is acceptable on the basis of seismic interpretation but the integration of 3d model reconstruction and 3d geomechanical restoration validates only the scenario with a single stage of deformation the 3d model highlights along strike variations of the structural style for the trapanese unit where pre existing discontinuities e g inherited mesozoic normal faults played an important role in the preferential occurrence of hinterland verging structures in detail backthrusts n verging are dissected by tear faults along the mt kumeta structure whereas an imbricate backthrust system evolves into thrust along the mt rocca busambra structure shortening estimate indicates low amount of internal deformation affecting the carbonate platform unit

fossil travertine system and its palaeofluid provenance migration and evolution through time example from the geothermal area of acquasanta terme central italy abstract the geothermal area of acquasanta terme has often been studied for its active and fossil travertine deposits to elucidate fluid origin geodynamic and hydrological setting even though present day thermal springs are usually used to obtain most information the three travertine terraces bordering the tronto river contain a plethora of information a combination of elemental and isotope analyses 18o 13c and 87sr 86sr ratio fluid inclusion microthermometry and u th dating is used to verify the hydrogeology and its timing these analyses point out two fluid reservoirs with distinctly different fluids one with low salinity of 0 7 wt nacl eq and another with 28 5 wt nacl eq which corresponds to the fluid composition of present day spring fluids furthermore it is demonstrated that geothermal sources were intermittently active in the past 221 ka mainly during uneven numbered marine isotope stages which are related to humid interglacial periods and resulted in three different travertine terraces around 210 5 126 5 and 36 5 ka accordingly an uplift rate for this area could be estimated at around 1 mm ka the fluids were tapped at a depth of approximately 3 km in the tectonized cataclastic fraction of the triassic anidriti di burano formation the calcare cavernoso formation and are originally meteoric based on geochemical evidence of a uniform 87sr 86sr ratio of 0 707914 0 00019 and a 18oaragonite value of 11 90 0 34 which has been depressed by elevated precipitation temperatures between 22 2 and 50 c the characterization and dating of fossil travertine deposits gives valuable data providing insights in long term fluid flow and orogenic uplift rates adding valuable information to present day spring fluid characterization

mineralogy and diagenesis of 3 24ga meteorite impact spherules abstract spherules in the s3 bed of the barberton greenstone belt south africa are distal fallout formed within an impact plume after a large impact event at 3 24 ga since that time diagenesis and lower greenschist grade metamorphism of the spherules has changed the mineralogy though shape and texture are largely preserved alteration of the s3 bed has resulted in spherules composed of quartz phyllosilicates ti and fe oxides and some ni rich chromites initially glassy spherules were palagonitized and silica cementation of the spherules began during low temperature interaction with seawater further alteration by si and k rich fluids resulted in a mineralogical assemblage of quartz feldspar and clays crystalline minerals were replaced by dissolution precipitation processes preserving relict textures further silica cementation resulted in complete lithification of the bed most of this alteration occurred at the seafloor and during shallow burial with continued burial amorphous silica recrystallized to microcrystalline quartz later recrystallization of clays to micas occurred during regional metamorphism at peak temperatures of 300 320 c late stage shearing and mineralization preferentially affected the northern region of the belt samples from different sections record highly variable local conditions water depth the amount of pre depositional transport location within the belt and proximity to igneous dikes all affect the diagenesis of the s3 spherules silica and barite concentrations are lower and carbonate concentrations are higher in the deep water depositional environments element mobility during diagenetic and lower greenschist grade metamorphism can be inferred based on studies of multiple sections throughout the bgb the most immobile elements are al zr ti sc and the high field strength elements and present element ratios can be used to infer original composition of the spherules the large ion lithophile elements are highly mobile as are the light rare earth elements rees which are particularly susceptible to mobilization during carbonate diagenesis and phosphate authigenesis of the rees ce and eu show the largest variability suggesting significant mobilization during diagenesis and low grade metamorphism consistent cr ir ratios particularly in the high concentrations suggest limited mobility and segregation of platinum group elements into ni rich chromite bearing spherules sulfide mineralization has not affected the ir concentration in the s3 layer

assessing the origin of sr and nd isotopes and ree y in middle upper pleistocene travertines from the acquasanta terme area marche central italy and implications for neotectonics abstract pleistocene bedded travertines from acquasanta terme display ranges of sr and ree y contents 462 1576 mg kg and 250 13 789 ng g respectively which are consistent with an evaporitic rock source paas normalized ree y patterns may support the origin of travertine bearing fluids from marine rocks travertines exhibit a very narrow range of 87sr values from 1 9 to 1 84 or 87sr 86sr ratios from 0 70782 6 to 0 70786 6 indicating an unchanged rock source throughout the travertine depositional time from about 350 to 26 ka likely represented by burano evaporites upper triassic as suggested by previous authors no sr contribution from magmatic sources has been detected travertines also display a very narrow range of nd values from 9 1 to 7 8 or 143nd 144nd ratios from 0 51217 to 0 51224 indicating an unchanged source also for ree y through time likely the same one providing sr lastly chemical and isotopic data of acquasanta travertines have been compared with those of bedded travertines from semproniano tuscany of similar age in particular 87sr values clearly distinguish between the two groups in agreement with their different rock sources as a whole these new geochemical and isotopic data on acquasanta travertines have provided a deeper insight into the origin of their parent hydrothermal fluids which upwelling from significant depth circulated through an area still affected by major seismic activity in particular the application of nd isotopes has resulted useful as unlike sr isotopes of fluid which tend to re equilibrate rather quickly with rocks along upwelling pathways nd isotopes sluggishly do so thus better reflecting the fluid source

styles of tectonic inversion within syn orogenic basins examples from the central apennines italy the geometry of several thrust related folds in the central apennines of italy results from a switch in deformation regime from extension to contraction this switch in tectonic regime occurred during the deposition of syn orogenic sediments and the emplacement and migration of the thrust belt foredeep system towards the foreland in neogene time the styles of positive tectonic inversion result from normal faults that were steepened rotated and truncated by thrusts with local development of minor folds due to buttressing normal fault controlled escarpments are also locally preserved in the forelimbs and backlimbs of thrust related anticlines the location and amplitudes of contractional structures across the belt reflects the distribution of pre thrusting normal faults within precursor syn orogenic basins a result that may improve our understanding of the evolution of apennine as well as other thrust belt foredeep systems

seismogenic sources in the adriatic domain abstract we present an overview of the seismogenic source model of the adriatic domain included in the latest version of the diss database http diss rm ingv it diss and in the european share database http diss rm ingv it share the model consists of composite and individual seismogenic sources located inside and along the margins of the adria plate in order to locate and parameterize the sources we integrated a wide set of geological geophysical seismological and geodynamic data either available from published literature or resulting from our own field work seismic profile interpretations and numerical modelling studies we grouped the sources into five regions based on geometrical and kinematic homogeneity criteria seismogenic sources of the central western adriatic north eastern adriatic eastern adriatic and central adriatic regions belong to the northern apennines external dinarides and offshore domains respectively they are characterized by nw se strike reverse to oblique kinematics and shallow crustal seismogenic depth seismogenic sources of the southern western adriatic region instead are e w striking dextral strike slip faults cutting both the upper and lower crust the fastest moving seismogenic sources are the most southern thrusts of the eastern adriatic and the strike slip sources of the southern western adriatic while the seismogenic sources of the central adriatic exhibit the lowest slip rates estimates of maximum magnitude are generally in good agreement with the historical and instrumental earthquake records except for the north eastern adriatic region where seismogenic sources exhibit a potential for large earthquakes even though no strong events have been reported or registered all sources included in the database are fully geometrically and kinematically parameterized and can be incorportaed in seismic hazard calculations and earthquake or tsunami scenario simulations

foreland dipping normal faults in the inner edges of syn orogenic basins a case from the central apennines italy abstract extensional deformations are common within foredeep basins and generally consist of hinterland dipping normal faults located at the foredeep foreland transition zones foreland dipping normal faults at the belt foredeep boundaries by contrast are far less documented and their occurrence is not predicted by simple orogenic load models new surface data integrated with seismic reflection profiles across the central apennines of italy reveal the occurrence of foreland dipping normal faults located in the inner edges of foredeep depressions extensional deformations are systematically found within sequentially younger tortonian messinian and early pliocene foredeep basins thus suggesting that normal fault development was an intrinsic feature of the evolving belt foredeep foreland system and could have influenced the stratal architectures of the host syn orogenic deposits foreland extension is consistent with existing geodynamic models for the apennines and could represent the effects of lithospheric bending its recognition and documentation elsewhere could provide significant insights to improve our understanding of syn orogenic basin dynamics

distribution of joints in the hinge line culmination of foreland verging overturned anticlines an example from the montagna dei fiori structure in the central apennines of italym francioni et al distribution of joints in overturned anticlines the distribution of joints veins and shear fractures in the montagna dei fiori overturned anticline is here reported two joint sets longitudinal and transverse to the nnw sse anticline axial trend and a conjugate system of shear fractures are recognized the transverse and longitudinal joint sets have a pre folding development likely related to the foreland foredeep flexure the transverse joints were reopened during layer parallel shortening along with the development of the shear fractures then during syn folding outer arc extension and hinge line culmination fold axial parallel extension both the longitudinal and transverse joints were enhanced and reactivated respectively

dip range for intracontinental reverse fault ruptures truth not stranger than friction abstract histograms of fault dips have been compiled for moderate to large m 5 5 reverse slip intracontinental earthquakes with the slip vector raking 90 30 in the fault plane the principal data set is restricted to earthquakes where the fault plane in the focal mechanism can be unambiguously distinguished from the auxilliary plane the reverse fault dips are bracketed within the range 12 1 the observed dip range is consistent with reactivation of faults possessing rock friction coefficients within byerlee9s 1978 range 0 85 s 0 6 undergoing frictional lockup at dips approaching 60 the broad 25 to 35 peak may arise from progressive domino steepening of imbricate reverse faults above the optimal dip for reactivation in regions undergoing bulk shortening paucity of very low angle thrusts implies that it is generally the steeper ramps within ramp flat assemblages that fail in moderate to large earthquakes the subsidiary peak at 45 to 55 likely results from compressional reactivation of former normal faults in areas undergoing tectonic inversion requiring some degree of fluid overpressuring the results are consistent with previous studies on the dip range for active normal faults that again demonstrate frictional lockup at reactivation angles approaching 60 together these analyses suggest that byerlee friction coefficients apply to faults with displacements of up to a few kilometers

hangingwall bed rotation and the development of contractional and extensional structures around a thrust fault geometric and experimental models abstract tectonic inversion of normal faults and development of extensional and contractional structures in the vicinity of thrust faults were studied using two models i a geometric or rigid model and ii an experimental or brittle ductile model the first model is based on simple trigonometric relationships between shortening rotation of layers along a thrust and dip of the thrust the model may be used to understand the structures at upper levels of the earth s crust in a predominant brittle regime the second model is based on a series of experiments performed with clay analogues it simulated the structures forming at a deeper level in a brittle ductile regime and incorporates folding as an essential feature the results of the study reveal that structures near a thrust fault depend on the thrust geometry and dip amount the initial orientation of hangingwall layers and their rheological properties in the absence of frictional effects along a thrust surface the rotation of layers and consequent displacement is directly proportional to the thrust dip since the listric faults are characterized by a decrease of dip with depth the variation in the rotation of layers in a profile section may result in formation of dilation spaces that may serve as potential sites for secondary mineral deposits or oil traps a large rotation of hangingwall layers results in a reverse fault drag and a small rotation caused by frictional effects along the fault produces normal fault drag

structural inheritance in mountain belts an alpine apennine perspective abstract the geological structure of continental lithosphere shows complex variety that is inherited into orogenic belts and influences the localization and amplification of contractional structures during mountain building in the alpine apennine sector together with other sectors of the tethyan orogenic system the pre orogenic crustal template can include arrays of extensional faults other faults can form adjacent to the evolving mountain belt and subsequently become incorporated as the thrust belts migrate into their forelands while in some areas these inherited features may simply reactivate under inversion more commonly faults show complex partial reactivation structures in volumes of distributed strain faults may serve to nucleate large scale buckle folds for example along basement cover interfaces these different patterns of basement reactivation may reflect spatially varying strength depth profiles in continental lithosphere that are themselves inherited from spatially distinct geological histories even when not themselves reactivating basement faults can control deformation in the overlying sedimentary cover by offsetting otherwise regionally extensive detachment horizons the 3d form of thrust systems can be strongly compartmentalized by pre existing cross faults such as the oblique lineaments of the apennines on a large scale the distribution of pre existing faults and other weaknesses may affect the propensity for orogenic contraction in basement and therefore directly control larger scale tectonic processes in the central mediterranean the evolution of slab roll back and the related growth of overlying extensional basins e g tyrrhenian sea may be strongly modulated by the distribution of rift related weak zones in the adjacent continental crust the subduction of continental crust will strongly depend on the inherited structure of this crust specifically the distribution of deep crust of basic composition this develops relatively higher densities associated with eclogite metamorphism which act in turn to reduce the buoyancy of thickened continental crust that otherwise serves to inhibit further shortening investigating all these aspects from the scale of bulk crustal compositions to the geometry timing and strength of earlier fault zones preserved in orogenic belts requires the integration of substantial multidisciplinary geological data sets the extent to which continental orogenic belts represent the amplification of inherited geological heterogeneities as opposed to self ordered phenomena modulated by the syntectonic environment remains unclear

early archaean spherule beds in the barberton mountain land south africa no evidence for impact origin abstract detailed petrographical and geochemical studies are reported for several well documented occurrences of spherule rich layers in the barberton mountain land south africa which were previously inferred by lowe and co workers to be the result of early archaean meteorite impacts in contrast we made the following observations the textures of most spherules are not necessarily the result of impact but could instead be the product of radial or intersertal growth of crystals during secondary mineral formation there is no difference in the content of siderophile elements between spherule layers and layers devoid of spherules the siderophile element abundances are high where sulphide minerals e g pyrite gersdorffite and chalcopyrite and or chromite are present independent of the presence or absence of spherules high contents of e g ir up to 2700 ppb ni 0 96 wt and cr 1 6 wt were found in various samples abundances of these elements in chondritic meteorites are approximately 600 ppb 1 4 wt and 0 35 wt respectively resulting in respective meteoritic components in these samples of 450 70 and 460 we do not accept these high concentrations as primary meteoritic signatures impact melt rocks have typically 1 of a meteoritic component furthermore spherules of any kind are very rare in known impact deposits including the k t boundary if present at all they are not usually associated with any significant ir or pge anomaly the high abundances of the siderophile elements in some barberton samples and their enrichment in secondary minerals indicate that these elements have been remobilized and reconcentrated the pge interelement ratios have changed during remobilization as well thus the pge abundance patterns and ratios are not primary and cannot be used as an argument in favour of an impact origin either nickel rich cr spinels which are found in some of the barberton spherule samples have low fe 3 fe total ratios these ratios are incompatible with an extraterrestrial or impact origin because such impact derived spinels including those found at the k t boundary are highly oxidized and also have different chemical compositions there is also no indication of any evidence of shock metamorphism associated with the barberton spherule layers which is the commonly accepted definitive criterion for recognition of an impact origin this is unusual because such evidence is preserved even in heavily altered samples from deeply eroded archaean impact structures we conclude that while these spherule layers are clearly unusual and deserve further attention there is no convincing evidence for an origin by impact we suggest that they were formed by volcanic processes followed by extensive hydrothermal alteration

structural architecture of the central apennines interpretation of the crop 11 seismic profile from the adriatic coast to the orographic divide 1 we present an interpretation of the eastern half portion of the crop 11 line a deep reflection seismic profile 265 km long that cuts across the central apennines from the tyrrhenian coast to the adriatic coast in the study area the line cuts across a pile of thrust sheets that underwent tectonic transport between the messinian and the pleistocene in its easternmost part the line runs through the plio pleistocene deposits of the adriatic foredeep in the foreland region the crop 11 line integrates previous information on the crustal structure derived from petroleum exploration and from deep seismic sounding refraction experiments in particular the crop 11 line confirms the existence of a very thick sedimentary sequence underlying the mesozoic tertiary carbonates of the apulia platform interpreted as the paleozoic triassic sedimentary cover of a pre cambrian crystalline basement in the mountain chain where the base thrust of the orogenic wedge reaches a depth of about 25 km this sedimentary sequence appears to be the deepest geological unit incorporated in the thrust system this interpretation of the crop 11 profile suggests an unusual thin skin tectonic style implying the detachment from the original basement and the incorporation in the post tortonian tectonic wedge of a very thick paleozoic triassic sedimentary sequence possibly affected by low grade metamorphism in the lower part other new suggestions from the crop 11 seismic data concern the origin of the fucino basin one of the most remarkable plio pleistocene intramontane basins the normal faults bordering this structural depression as other important normal faults present in the central apennines e g the caramanico fault system in the majella region seem to have been controlled by gravitational collapse processes driven by uplift during crustal shortening rather than by a generalized extension subsequent to the apennine compression as usually reported in the geological literature if this interpretation is correct the strong seismic activity in correspondence to the apennine watershed may be related to the very recent increase in the structural relief caused by an out of sequence propagation of the active thrusts

thrust belt development in the central apennines italy northward polarity of thrusting and out of sequence deformations in the gran sasso chain the lazio abruzzi carbonate platform overrides the outermost sectors of the foreland fold and thrust belt of the central apennines of italy along an arcuate thrust front which swings from e w to nnw sse orientation the e w striking north verging thrust faults of the gran sasso cut in their footwall the n s oriented east verging imbricates of the marche thrust belt and the adjacent adriatic foredeep our field mapping of the gran sasso imbricate system shows an array of six major thrust faults crosscutting each other in such a way that oblique propagation of higher thrust faults across the preexisting thrust sheets causes rethrusting of earlier imbricated units decapitation of previous folds and superposition of younger on older beds deformation in the gran sasso thrust belt mainly occurred between messinian and middle pliocene times and is partly synchronous with the development of the marche thrust belt thus implying that shortening resulted from a complex combination of northward and eastward propagating thrust systems increasing west to east shortening along the gran sasso thrust front indicates large differential anticlockwise rotation by decoupling along a n s transpressive right lateral shear zone this mechanism could have been induced by the maiella foreland uplift acting as a buttress against which the lazio abruzzi carbonate platform was stacked and forced to rotate anticlockwise with consequent shortening by out of sequence thrust propagation

thick skinned tectonics and basement involved fold thrust belts insights from selected cenozoic orogens defining the structural style of fold thrust belts and understanding the controlling factors are necessary steps towards prediction of their long term and short term dynamics including seismic hazard and to assess their potential in terms of hydrocarbon exploration while the thin skinned structural style has long been a fashionable view for outer parts of orogens worldwide a wealth of new geological and geophysical studies has pointed out that a description in terms of thick skinned deformation is in many cases more appropriate this paper aims at providing a review of what we know about basement involved shortening in foreland fold thrust belts on the basis of the examination of selected cenozoic orogens after describing how structural interpretations of fold thrust belts have evolved through time this paper addresses how and the extent to which basement tectonics influence their geometry and their kinematics and emphasizes the key control exerted by lithosphere rheology including structural and thermal inheritance and local regional boundary conditions on the occurrence of thick skinned tectonics in the outer parts of orogens

tectonic units of the alpine collision zone between eastern alps and western turkey abstract we present a map that correlates tectonic units between alps and western turkey accompanied by a text providing access to literature data explaining the concepts used for defining the mapped tectonic units and first order paleogeographic inferences along strike similarities and differences of the alpine eastern mediterranean orogenic system are discussed the map allows 1 for superimposing additional information such as e g post tectonic sedimentary basins manifestations of magmatic activity onto a coherent tectonic framework and 2 for outlining the major features of the alpine eastern mediterranean orogen dinarides hellenides anatolides and taurides are orogens of opposite subduction polarity and direction of major transport with respect to alps and carpathians and polarity switches across the mid hungarian fault zone the dinarides hellenides taurides and apennines consist of nappes detached from the greater adriatic continental margin during cretaceous and cenozoic orogeny internal units form composite nappes that passively carry ophiolites obducted in the latest jurassic earliest cretaceous or during the late cretaceous on top of the greater adriatic margin successions the ophiolites on top of composite nappes do not represent oceanic sutures zones but root in the suture zones of neotethys that formed after obduction suturing between greater adria and the northern and eastern neotethys margin occupied by the tisza and dacia mega units and the pontides occurred in the latest cretaceous along the sava izmir ankara erzincan suture zones the rhodopian orogen is interpreted as a deep crustal nappe stack formed in tandem with the carpatho balkanides fold thrust belt now exposed in a giant core complex exhumed in late eocene to miocene times from below the carpatho balkan orogen and the circum rhodope unit its tectonic position is similar to that of the sakarya unit of the pontides we infer that the rhodope nappe stack formed due to north directed thrusting both rhodopes and pontides are suspected to preserve the westernmost relics of the suture zone of paleotethys

the effects of pre existing discontinuities on the surface expression of normal faults insights from wet clay analog modeling abstract we use wet clay analog models to investigate how pre existing discontinuities i e structures inherited from previous tectonic phases affect the evolution of a normal fault at the earth s surface to this end we first perform a series of three reference experiments driven by a 45 dipping master fault unaffected by pre existing discontinuities to generate a mechanically isotropic learning set of models we then replicate the experiment six times introducing a 60 dipping precut in the clay cake each time with a different attitude and orientation with respect to an initially blind 45 dipping master normal fault in all experiments the precut intersects the vertical projection of the master fault halfway between the center and the right hand lateral tip all other conditions are identical for all seven models by comparing the results obtained from the mechanically isotropic experiments with results from experiments with precuts we find that the surface evolution of the normal fault varies depending on the precut orientation in most cases the parameters of newly forming faults are strongly influenced the largest influence is exerted by synthetic and antithetic discontinuities trending respectively at 30 and 45 from the strike of the master fault whereas a synthetic discontinuity at 60 and an antithetic discontinuity at 30 show moderate influence little influence is exerted by a synthetic discontinuity at 45 and an antithetic discontinuity at 60 from the strike of the master fault we provide a ranking chart to assess fault to discontinuity interactions with respect to essential surface fault descriptors such as segmentation vertical displacement profile maximum displacement and length often used as proxies to infer fault properties at depth considering a single descriptor the amount of deviation induced by different precuts varies from case to case in a rather unpredictable fashion multiple observables should be taken into consideration when analyzing normal faults evolving next to pre existing discontinuities

the interaction of extensional and contractional deformations in the outer zones of the central apennines italy abstract the relationships among normal faults and thrusts in the apennines of italy are often unclear and the local absence of syn tectonic stratigraphic controls have led to contrasting interpretations on the relative chronology for both classes of structures the activity of normal faults has been variously regarded as due to pre syn or post orogenic extension and the contrasting evidence from different sites has produced an ongoing debate on the normal fault thrust interaction the results of a kinematic analysis on selected composite structures of the outer zones of the central apennines make it possible to unequivocally establish a relative chronology of extensional and contractional deformations detailed mapping outcrop scale observations and structural overprinting relationships support a positive inversion tectonic history where normal faults and fault controlled escarpments formed first and were later deformed by thrusts and related folds all normal faults control the distribution of foredeep deposits thus indicating that the recognised episode of positive inversion is related to the incipient stages of construction of the apennine thrust belt the systematic collection of structural data may help to unravel the evolution of adjacent sectors of the apennine chain as well as of other belt foredeep foreland systems whose extension contraction relationships are poorly constrained

fault segmentation as constraint to the occurrence of the main shocks of the 2016 central italy seismic sequence we perform the finite extent fault inversion of the three main events of the 2016 central italy seismic sequence using near source strong motion records we demonstrate that both earthquakes nucleation and rupture propagation were controlled by segmentation of the n nw s se trending quaternary normal faults the first shock of the sequence august 24th mw 6 0 ruptured at the relay zone between the laga mts lf and the cordone del vettore cvf normal faults the second shock october 26th mw 5 9 nucleated at a minor relay zone within the mt vettore mt bove fault vbf while the third and largest one october 30th mw 6 5 initiated at the relay zone between the vbf and cvf triggering the multiple rupture of the vbf cvf and probably lf we show that this latter relay zone corresponds to the deeper high angle fault zone of the sibillini mts cross structure a thrust ramp inherited from the miocene pliocene contractional phase of the apennines this structure acted as a barrier to rupture propagation of the first two events thus defining an area of large stress concentration until it acted as the initiator of the rupture originating the largest mw 6 5 event that crossed the barrier itself we suggest that the young cvf have started to cut through the barrier acting as a soft linkage between the two long lived lf and vbf the evidence that coseismic cumulative slip shows a maximum at the cvf provided by both slip inversion and original surface rupture data suggests that the cvf is growing faster than the adjacent faults

comparing slip distribution of an active fault system at various timescales insights for the evolution of the mt vettore mt bove fault system in central apennines

lateral variations in tectonic style across cross strike discontinuities an example from the central apennines belt italy in foreland thrust belts abrupt lateral changes in tectonic style structural stratigraphic features and topography usually occur across cross strike faults the central apennines of italy offer an exceptional scenario of lateral variations in tectonic setting here the sangro volturno oblique thrust ramp svotr represents the outer thrust front of the pliocene quaternary foreland thrust system confining southward the axial culmination of the orogen that occurs in the central apennines we present an interpretation of the pliocene quaternary evolution of this cross strike fault through an integrated dataset including structural geological mapping and subsurface onshore seismic reflection profiles the interpretation of the structural framework is augmented by the analysis of low temperature thermochronometers from 32 new sites extending across the subsurface transverse structure as evidenced by seismic line interpretation the localization and development of the svotr have been influenced by inherited extensional faults within a positive inversion tectonics context the regional distribution of the maximum paleotemperature values across the svotr constrains the original extent of the allochthonous thrust sheet over all its hanging wall and footwall blocks the pliocene quaternary thrusting and inversion of svotr caused the strong hanging wall uplift which brought to the complete erosion of the allochthonous units and the exhumation of the adria units the integrated analysis of low temperature thermochronometers and structural evidence as applied in the study case can define the role of major cross strike discontinuities in foreland thrust belts by constraining and verifying their tectonics inversion significance and the amount of related exhumation

the role of pre existing thrust faults and topography on the styles of extension in the gran sasso range central italy abstract structural analysis and field mapping together with simple geometrical and flexural elastic models document that two styles of quaternary extensional tectonics characterized the gran sasso range central apennines italy in the western part of the range extension took place on 10 15 km long range front normal faults with associated 600 1000 m high escarpments showing evidence of late glacial holocene activity this topography has been reproduced with a thin elastic plate subjected to the isostatic forces induced by the movement along high angle 55 65 planar normal faults in the eastern part of the belt extension occurred on shallow dipping normal faults 30 35 which reactivated progressively deeper pre existing thrusts in this area antithetic domino faults formed to accommodate the mechanical adjustment of the hanging wall over a variably dipping major fault surface the eastward increase in shortening due to the earlier compressional phase documented in the gran sasso belt by previous authors accounts for the more developed zones of weakness and high topographic relief in the eastern sector this setting could explain the different styles of extension and the more advanced northeastern limit of normal faulting in the eastern sector this work suggests that normal faults can originate either with low or high angle geometry in the upper crust according to the pre existing tectonic setting and that topography could be important in controlling the geometry and pattern of migrating normal faulting

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

relationships between thrusts and normal faults in curved belts new insight in the inversion tectonics of the central northern apennines italy abstract the relationships between thrusts and normal faults represent primary constraints in the reconstruction of the modes and timing of pre syn and post orogenic deformation events in fold and thrust belts such relationships are well exposed in curved orogenic belts where the thrusts are oblique to the trend of normal faults we study the nne ssw trending olevano antrodoco sibillini oblique thrust and its crosscutting relationships with nw se trending normal faults in order to constrain the neogene quaternary deformation history of the central northern apennine italy the analysis of structural and geological data allowed us to reconstruct the geometric and kinematic constraints of two inversion events 1 during the pliocene positive inversion reactivated the nne ssw trending pre existing ancona anzio normal fault as the olevano antrodoco sibillini oblique thrust ramp and caused the shortcut of nw se oriented normal faults 2 during the quaternary negative inversion reactivated nw se trending pre thrusting normal faults the growth of the nw se quaternary normal faults causes seismicity and is responsible of the development of wide quaternary intramontane basins their distribution and the related seismicity have been controlled and compartmentalized by nne ssw trending oblique thrusts thus the crosscutting relationships between thrusts and normal faults are crucial in seismic hazard assessment

early archean spherule beds chromium isotopes confirm origin through multiple impacts of projectiles of carbonaceous chondrite type three early archean spherule beds from barberton south africa have anomalous cr isotope compositions in addition to large ir anomalies confirming the presence of meteoritic material with a composition similar to that in carbonaceous chondrites the extra terrestrial components in beds s2 s3 and s4 are estimated to be approx l 50 60 and 15 30 respectively these beds are probably the distal and possibly global ejecta from major large body impacts these impacts were probably much larger than the cretaceous tertiary event and all occurred over an interval of approx 20 m y implying an impactor flux at 3 2 ga that was more than an order of magnitude greater than the present flux

the gubbio normal fault central italy geometry displacement distribution and tectonic evolution abstract normal faults within orogenic belts can be pre syn or post orogenic features we studied the gubbio normal fault central italy which is an example of a pre orogenic fault reactivated in a post orogenic stage the gubbio fault is a 22 km long fault bordering a quaternary basin and part of an active faults system in the umbria marche region central italy the interpretation of a set of seismic profiles enables us to reconstruct the fault geometry in detail and to measure displacement and throw distributions along the fault strike seismic data indicate that the gubbio fault represents an example of multiple reactivation at least a portion of the fault was active in the miocene and only a part of the total displacement was achieved in the quaternary the reconstruction of the fault geometry at depth shows that the fault is characterised by listric geometry the fault is also characterised by a bend along strike and structure contours show that this geometry is maintained at depth as the fault is commonly addressed as presently active the maximum fault dimensions are correlated to the maximum expected earthquake and the presence of the fault bend is discussed as a possible barrier to seismic ruptures propagation

palinspastic restoration and paleogeographic reconstruction of the peri tyrrhenian area during the neogene abstract this paper presents the results of research carried out on the paleogeographic and geodynamic post collisional evolution of the peri tyrrhenian area from the southern alps to sicily during this post collisional evolution a back arc area thrust belt foredeep system developed in which the following tectono sedimentary zones can be distinguished from the external to the internal ones the foreland zone connected to the foredeep through a slope generally controlled by normal faults the foredeep an assymmetric depression with strong subsidence related to the compressional activity of the thrust zone the chain whose outward migration from the late oligocene onward was discontinuus with important stages of crisis partially connected to the mechanical response of different crustal thicknesses existing in the foreland the discontinuous satellite basins developed within the thrust belt the back arc basins developed in the inner part of the chain where the superposition of the extensional tectonics over previous compressional domains causes the fragmentation of the thrust belt leading to its destruction according to this model seven palinspatic maps are discussed regarding the following time intervals late oligocene 25 24 m y burdigalian 22 20 m y langhian 17 16 m y serravallin 15 13 m y tortonian 10 9 m y late messinian 5 5 5 3 m y and early pliocene 5 3 4 6 m y during five of these time intervals significant geodynamic modifications occurred in the whole peri tyrrhenian area leading to paleogeographic changes in any case the geodynamic evolution of the whole area seems clearly controlled by the activity of important bundles of tectonic lines transversal to the chain which in the same time interval in the outermost part of the thrust belt separated areas with different values of shortening and in tthe most internal zones separated segments having different amount of extension these tectonic lines certainly have a crustal significance and have probably acted along previous formed discontinuities