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

origin of smectite and illite smectite in the barbados accretionary complex oxygen isotopic evidence oxygen isotopic and mixed layer compositional data are used to infer modes of formation of smectite and illite smectite from the barbados accretionary complex nearly pure smectites have 18 o values between 26 and 30 and apparently formed authigenically by alteration of volcanic ash illite smectites are thought to have formed in situ at temperatures less than 40 c although a detrital origin cannot be ruled out for several samples the unusually low temperature of transition of smectite to illite indicates that fluid generation by mineral dehydration and consequent structural effects can occur at shallow depths in accretionary complexes

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

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

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

present day stress in the surroundings of 2009 l aquila seismic sequence italy summary the axial zone of the apenninic belt in central italy is a tectonically active region affected by post orogenic quaternary extension the present day stress field is characterized by a minimum horizontal stress shmin ne sw oriented derived mainly from earthquake focal mechanisms and secondarily from borehole breakouts and fault data the paper describes the computation of the shmin orientation along two deep boreholes located in the vicinity of the area hit by the 2009 april 6 mw 6 3 l aquila earthquake the analysed wells show breakout zones at a depth range between 1 4 and 4 6 km giving precious information on a depth interval usually not investigated by any other data the results show an shmin n81 22 and n74 10 oriented for varoni 1 and campotosto 1 wells respectively the comparison among the breakouts the 2009 seismic sequence the past seismicity and the quaternary faults indicates a small rotation of shmin orientation from ne in the southern to ene in the northern sector of the study area where the wells are located these differences are linked both to the natural variations of data and to the orientation of the main tectonic structures varying from nw se in the abruzzi region to n s moving toward the umbro marchean apennines the identification of constant shmin orientations with depth derived from all the examined active stress data confirms the breakouts as reliable stress indicators also for aseismic areas

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

human impact in the holocene fluvial and coastal evolution of the marche region central italy abstract today the coasts of the marche region are represented by almost continuous rectilinea sand beaches except in the north at the border with the romagna region and in the central part around the conero ridge where there are active rock cliffs the sandy coasts are protected almost everywhere by artificial barriers built up as a protection against the general tendency to retreat along some tracts the coastal erosion started at the beginning of this century but became generalized after 1940 1950 this was mainly due first to the reduction in sediment supply following the improvement in agricultural techniques after the italian unification and later to the widespread extraction of gravels from the thalwegs related to the rapid increase in urban population in the 1950s however in the same period along the rivers there was a widespread creation of artificial levees to prevent lateral erosion or flooding and to extend areas suitable for agriculture following these practices the lower middle tracts of the rivers underwent a strong vertical downcutting which increased as a result of the creation of checkdams downvalley of many bridges which contributed to the store of the sediments in the upper part of the valleys at present most of the rivers have an irregular course and are deeply entrenched in the bedrock or inside their own sediments up to the beginning of the century most of the lower tracts of the valleys were characterized by strong aggradation in a braidplain system this aggradation started as early as the middle ages 1100 ad but increased after the renaissance as a consequence of a generalized deforestation of the periadriatic basin and the following severe soil erosion in the mean time the coast underwent a very fast progradation in some places more than 500 m small deltas were created at the mouths of the rivers and longshore bars and sandy beaches began to occupy the base of the active cliffs which previously extended between one river and another however in the mountain parts of the river basins a meander course existed and in many cases still exists expecially where the human interventions were of limited extent before 1000 1100 ad all the rivers had a meander pattern and at the junction with the sea entered lagoons and swamps in most cases protected by littoral barrier beaches these conditions were established earlier than the third century bc and have been attributed to the first systematic land clearance and the following soil erosion during the bronze and iron ages at that time the regional coastline became almost rectilinear but with many active cliffs between one river and another before being affected by a major human impact earlier than 4000 years bp the natural coastal environment was represented by active rock cliffs which alternated with pocket beaches corresponding to a river mouth in some rivers embayments and beaches were located up to 4 5 km inland from the present day position after the flandrian transgression the evidence presented reveals major changes that can be attributed to human impact

shear wave splitting of the 2009 l aquila seismic sequence fluid saturated microcracks and crustal fractures in the abruzzi region central apennines 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

paleomagnetism and the orocline hypothesis eldredge s bachtadse v and van der voo r 1985 paleomagnetism and the orocline hypothesis in n l carter and s uyeda editors collision tectonics deformation of continental lithosphere tectonophysics 119 153 179 oroclines were originally defined by carey as curved mountain belts which initially were straight or at feast straighter than they are today in the last few years the definition has been broadened to include any curved mountain belt regardless of its original shape since the occurrence of oroclinal bending is best recorded in the change of declination as a function of tectonic setting paleomagnetic and structural data from six potential oroclines have been compiled and analyzed to determine the amount of rotation displayed by the change of paleomagnetic declination relative to the change in strike of the fold belt the arcuate belts investigated are the sicilian calabr n arc and the umbrian arc of italy the swiss portion of the jura mountains the central portion of the appalachian mountains from pennsylvania to virginia u s a the wyoming idaho overthrust belt of western north america and the hercynides of western and central europe the jura mountains and the pennsylvania virginia portion of the appalachians fail to show significant oroclinal bending the wyoming idaho belt shows a combination of rotated possibly oroclinai and unrotated thrust sheets in the sicilian calabrian arc significant oroclinat bending caused by the impingement of the calabria peloritani nappes in the late tertiary can be demonstrated while the umbrian arc of similar age in the northern apennines also shows oroclinal bending on a smaller scale hercynian europe the only belt included in which deformation of basement rocks can be demonstrated shows oroclinal bending at least so as well as a marked original curvature 70 in its western part common to all the orociines studied in this paper is the probable impingement of a rigid block or continental margin during the orogeny causing subsequent deformation and bending of the fold belt

active tectonics in central italy constraints from surface wave tomography and source moment tensor inversion abstract we investigate the lithosphere asthenosphere structure and active tectonics of central italy with emphasis on the umbria marche area by means of surface wave tomography and seismic moment tensor inversion the data include a large number of short period local and regional group velocity measurements sampling the umbria marche apennines and the adria margin respectively incorporation of published phase velocity measurements sampling italy and surroundings results from deep seismic soundings which go through the umbria marche area the local group velocity maps covering the area reactivated by the 1997 1998 umbria marche earthquake sequence suggest an intimate relationship between the lateral earth structure variations and the distribution of the active fault systems and related sedimentary basins the upper crustal models reveal the importance of inherited compressional tectonics on the recent extensional deformation and associated seismic activity source inversion studies of the main events of the 1997 earthquake sequence show the dominance of normal faulting mechanisms whereas selected aftershocks between the fault segments at the step over reveal that the prevailing deformation is of strike slip faulting type at the regional scale the crust exhibits clear layering and varies in thickness from about 25 km below the tuscan metamorphic complex tmc to about 30 km below the val tiberina extensional thick sedimentary basin and reaches about 35 km below the umbria marche geological domain umd the lithospheric mantle lid is thin about 30 km below tmc while it is about 70 km thick below umd a lithospheric root about 120 km wide between the tmc and umd reaches a depth of at least 130 km a low velocity zone defined mantle wedge vs less than 4 2 km s in the uppermost mantle overlying the high velocity lid is detached this wedge is about 20 km thick and decouples the underlying lid from the crust the retrieved crust and upper mantle structure beneath central italy is in agreement with bouguer anomaly and heat flow data and supports a delamination process the high velocity upper mantle underlying the mantle wedge is inferred to be subcrustal lithospheric material delaminated from the overlying crust

the isotopic composition of radiogenic helium and its use to study groundwater movement in confined aquifers abstract the 3 he 4 he ratio for radiogenic he is shown to be primarily determined by the abundance of li and neutron absorbing elements in the host formations and is almost independent of the radioelement abundance the 3 he 4 he ratios have been computed for various li contents in rock matrices with average abundances of other elements the 3 he 4 he ratio is specific for each formation and may therefore be used to study crustal diffusion of he it is shown however that both the 3he and 4he contents of continental basements are likely to exceed those of the mantle so that diffusion of mantle he through continental crust is not likely to occur changes in the 3 he 4 he ratio for dissolved he have potential for studying groundwater movement and mixing processes atmospheric he which was dissolved at recharge is progressively diluted by radiogenic he with an isotopic ratio characteristic of the aquifer as the groundwater migrates down dip mixing proportions for formation he and atmospheric he in aquifers for which there is admixture of fracture borne water and interstitially stored water can also be estimated from isotopic measurements these processes are discussed in relation to two aquifers in eastern england

fingerprinting stress stylolite and calcite twinning paleopiezometry revealing the complexity of progressive stress patterns during folding the case of the monte nero anticline in the apennines italy in this study we show for the first time how quantitative stress estimates can be derived by combining calcite twinning and stylolite roughness stress fingerprinting techniques in a fold and thrust belt first we present a new method that gives access to stress inversion using tectonic stylolites without access to the stylolite surface and compare results with calcite twin inversion second we use our new approach to present a high resolution deformation and stress history that affected meso cenozoic limestone strata in the monte nero anticline during its late miocene pliocene growth in the umbria marche arcuate ridge northern apennines italy in this area an extensive stylolite joint vein network developed during layer parallel shortening lps as well as during and after folding stress fingerprinting illustrates how stress in the sedimentary strata did build up prior to folding during lps the stress regime oscillated between strike slip and compressional during lps before ultimately becoming strike slip again during late stage fold tightening our case study shows that high resolution stress fingerprinting is possible and that this novel method can be used to unravel temporal relationships that relate to local variations of regional orogenic stresses beyond regional implications this study validates our approach as a new powerful toolbox to high resolution stress fingerprinting in basins and orogens combining joint and vein analysis with sedimentary and tectonic stylolite and calcite twin inversion techniques

the neolithic site of maddalena di muccia umbria marche apennine italy a tip to reconstruct the geomorphological evolution and human occupation during the late pleistocene and the holocene abstract the geomorphological evolution of the upper chienti river basin during the late pleistocene and the holocene was characterized mainly by numerous landslides strongly affecting the river dynamics that produced falls deviations and in some cases total obstructions with the formation of lakes sometimes extending for some kilometres moreover particularly during the holocene phytoclastic and phytohermal travertine deposits were deposited in correspondence of steps along the river bed one of these deposits by means of radiocarbon dating has been dated between 8260 100 yr bp and 7740 80 yr bp stromatolithic travertine is also present at the base of holocene channels slightly incised on the top of the upper pleistocene alluvial plain the neolithic site of maddalena of muccia is located on an upper pleistocene alluvial terrace at the confluence of the two main tributaries of the river about 400 m a s l human presence in this alluvial plain zone lasted from the ancient neolithic to the roman period surely in relation to its strategic position connecting the adriatic and the tyrrhenian slants of the chain the richest and most important remains found at just 50 cm under the field level belong to the ancient and recent neolithic and to the aeneolithic and have been collocated between the vii and the v millennium bc using c14 during the archaeological excavations carried out by the archaeological superintendence of the marche region testimonies reveal a local economy that was primarily based on animal breeding cereal cultivation fishing and deforestation the study has evidenced that the river incision process usually started in other areas at the beginning of the holocene was strictly limited by the presence of steps and barrages that reduced sedimentation flows towards the initial sectors of the valleys within the calcareous apennine ridge the generalized deposition of travertine along the riverbeds and within the minor channels that developed at the top of the upper pleistocene alluvial plains also produced a sort of armature of the riverbed thus limiting further erosion processes the resumption of linear erosion coincided with the natural erosion of the dams previously caused by landslides and above all starting from about 4500 yr bp with the rapid decline of the travertine deposition due mainly to climatic conditions

helium accumulation in groundwater ii a model for the accumulation of the crustal 4he degassing flux abstract a model of 4 he accumulation in a confined aquifer is presented which includes in situ production and a crustal degassing flux of 4 he into the bottom of a confined aquifer the model is consistent with the measurements of 4 he concentration in the great artesian basin australia torgersen and clarke 1985 and also with the measurements of 4 he concentration in the auob sandstone of namibia heaton 1981 the measured value of the crustal degassing flux of 4 he from these two areas is comparable with the 4 he degassing flux calculated from the atmospheric budget of 4 he wasserburg et al 1963 ozima and podosek 1983 a literature review suggests that a crustal degassing 4 he source may account for the 4 he accumulation in many other groundwater systems it is concluded from the literature review the detailed modelling of 4 he accumulation in gab and the auob sandstone and the atmospheric budget that crustal degassing of 4 he may be a common and widespread phenomena

structural styles chronology rates of deformation and time space relationships in the umbria marche thrust system central apennines italy structural interpretation of geological and geophysical data available for the central apennines italy allowed us to draw balance and restore three geological profiles across the external zones of the umbria marche thrust system and to evaluate the timing and rates of deformation in a roughly 4 ma time window from late messinian to late pleistocene time from this data set we established a general correlation between spacing l and thickness d of the thrust sheets which was used as a depth correction factor for deriving local versus regional depths to the sole thrust and a time space relationship between the closing time of activity of each thrust and the distance x from a reference point within the system

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

an integrated analysis of transverse structures in the northern apennines italy abstract the northern apennines have been the object of numerous studies both from a morphological and a structural point of view at present much debate is going on about the existence and interpretation of ne sw alignments described by geomorphologists boccaletti m coli m napoleone g 1977 nuovi allineamenti strutturali da immagini landsat e rapporti con l attivita sismica negli appennini boll soc geol it 96 679 694 signorini r 1953 linee tettoniche trasversali nell appennino settentrionale rend acc naz lincei 6 42 45 and partly denied by structural geologists we show new microtectonic and morphological data which contribute to a more comprehensive interpretation of these elements stress axis determination and different morphotectonic analyses have been combined the analysis of the drainage networks and of two different digital elevation models have also been considered the results lead us to interpret the ne sw alignments as large and diffuse deformation zones which may represent old transfer zones active with left lateral strike slip movements during the mountain building

the anatomy of the 2009 l aquila normal fault system central italy imaged by high resolution foreshock and aftershock locations 1 on 6 april 01 32 utc 2009 a mw 6 1 normal faulting earthquake struck the axial area of the abruzzo region in central italy we study the geometry of fault segments using high resolution foreshock and aftershock locations two main sw dipping segments the l aquila and campotosto faults forming an en echelon system 40 km long nw trending the 16 km long l aquila fault shows a planar geometry with constant dip 48 through the entire upper crust down to 10 km depth the campotosto fault activated by three events with 5 0 mw 5 2 shows a striking listric geometry composed by planar segments with different dips along depth rather than a smoothly curving single fault surface the investigation of the spatiotemporal evolution of foreshock activity within the crustal volume where the subsequent l aquila main shock nucleated allows us to image the progressive activation of the main fault plane from the beginning of 2009 the foreshocks activated the deepest portion of the fault until a week before the main shock when the largest foreshock mw 4 0 triggered a minor antithetic segment seismicity jumped back to the main plane a few hours before the main shock secondary synthetic and antithetic fault segments are present both on the hanging and footwall of the system the stress tensor obtained by inverting focal mechanisms of the largest events reveals a ne trending extension and the majority of the aftershocks are kinematically consistent deviations from the dominant extensional strain pattern are observed for those earthquakes activating minor structures

frontal part of the northern apennines fold and thrust belt in the romagna marche area italy shallow and deep structural styles in this study surface geological data resulting from a detailed field survey including structural and biostratigraphic analysis have been integrated with subsurface seismic lines and well logs data in order to reconstruct the tectonic evolution of the external zones of the northern italian apennines in the romagna marche foothills and adriatic sea areas this integrated analysis shows 1 a late messinian to lower pleistocene progression of structural development from the hinterland to the foreland of the studied sector of the thrust belt 2 relatively limited 20 southward increasing amounts of shortening obtained by the construction of line length balanced and restored geological cross sections 3 a regional deformation style characterized by the presence of backthrusts associated with most foreland vergent thrust ramps leading to quasi symmetric uplift and a low critical taper for the wedge typical of foreland fold and thrust belts with a weak basal decollement triassic anhydrites in the present case 4 an important influence of basement faulting which despite a general basement cover decoupling appears to control stress localization in the latter producing linkage of basement and cover stuctures in a combination of thin and thick skinned tectonic styles and 5 contrasting structural styles characterizing deep features as imaged by seismic reflection profiles and shallow ones deep stuctures consist of growth anticlines bounded by major thrust ramps and back limb back thrusts separated by broader open synclines both involving a mesozoic paleogene mainly carbonate passive margin succession in the crestal zones of major anticlines shallow structures affecting neogene terrigenous foredeep sediments show a complex pattern of upright to recumbent folds of tens to hundreds of meters wavelength related to minor thrusts and backthrusts deformation of the mesozoic paleogene multilayer appears to be dominated by thrust propagation in the cores of early formed anticlines developed by buckling instabilities the overlying neogene deposits are detached from the carbonate substratum along the base of the foredeep succession bedding parallel slip occurring along this detachment level appears to be accommodated by the complex structures in the crests of major anticlines where the thrusts lramp to the surface cutting up section complex shallow structures interpreted to accommodate at shallow structural levels the deep deformation would therefore represent a geometrical requirement for maintaining strain compatibility across the shallow detachment level located at the base of the foredeep succession

active tectonics in the central apennines and possible implications for seismic hazard analysis in peninsular italy abstract the central apennines fault system cafs of peninsular italy overprints earlier structures of a neogene fold and thrust belt and includes segments characterized by diffuse seismicity distributed within a nnw sse trending zone 50 60 km wide the system has been analysed by means of morphotectonic and structural analysis of exposed active fault segments the resulting fault structure consists of an interconnecting network of roughly n s trending left lateral strike slip segments and mostly nw se oriented transtensional to normal faults evidence for recent activity of cafs structures is provided by faulted middle pleistocene holocene deposits including 30 40 ka old pyroclastites and 40 ka old palustrine sediments fresh scarps in both bedrock and late quaternary continental deposits and decametric lateral offsets locally affecting the post wurmian drainage pattern of the area the regional stress field responsible for the development and evolution of the cafs as inferred from fault slip data is characterized by a nw se compression and by a ne sw extension the cafs pattern and its present day kinematics have been related to left lateral strike slip motion on north south trending crustal faults the existence of deep seated strike slip faults in the central apennines has implications for seismic hazard analysis motion along these structures suggests in fact that coseismic surface faulting is distributed and that cumulative displacements include normal transtensional and strike slip components the seismogenic potential of cafs structures can therefore be best described by multiple rupture models and be better analysed in terms of partial contributions of lower rank features constituting congruent structural associations within the system

the terminology of structures in thrust belts abstract a review of structures and geometric relationships recognized in thrust belts is presented a thrust is defined as any contractional fault a corollary being that thrusts must cut up section in their transport direction flats are those portions of a thrust surface which were parallel to an arbitrary datum surface at the time of displacement and ramps are those portions of thrusts which cut across datum surfaces ramps are classified on the basis of their orientation relative to the thrust transport direction and whether they are cut offs in the hangingwall or footwall of the thrust lateral variations in the form of staircase trajectories are joined by oblique or lateral ramps which have a component of strike slip movement an array of thrusts which diverge in their transport direction may form by either of two propagation models these are termed piggy back propagation which is foreland directed and overstep propagation which is opposed to the thrust transport direction an array of thrust surfaces is termed an imbricate stack and should these surfaces anastamose upwards a duplex will result the fault bounded blocks are termed horses a duplex is bounded by a higher roof thrust and a lower floor thrust the intersection of any two thrust planes is termed a branch line thrusts can be classified on the basis of their relationship to asymmetric fold limbs which they cut a further classification arises from whether a particular thrust lies in the hangingwall or footwall of another one the movement of thrust sheets over corrugated surfaces or the local development of thrust structures beneath will fold higher thrust sheets these folds are termed culminations and their limbs are termed culmination walls accommodation of this folding may require movement on surfaces within the hangingwall of the active thrust these accommodation surfaces are termed hangingwall detachments and they need not root down into the active thrust this category of detachment includes dip slip hangingwall drop faults which are developed by differential uplift of duplex roofs and out of the syncline thrusts which develop from overtightened fold hinges back thrusts as well as forming as hangingwall detachments may also form due to layer parallel shortening above a sticking thrust or by rotation of the hangingwall above a ramp

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

hydrochemical baseline condition of groundwater at the mizunami underground research laboratory miu abstract hydrochemical conditions up to depths of 1000 m below ground level around the mizunami underground research laboratory were investigated to construct a baseline condition model describing the undisturbed hydrochemical environment prior to excavation of the underground facilities at mizunami gifu japan groundwater chemistry in this area was classified into a na ca hco 3 type of groundwater in the upper part of sedimentary rock sequence and a na ca cl type of groundwater in the deeper part of the sedimentary rock sequence and basement granite the residence time of the groundwaters was estimated from their 14 c contents to be approximately 9 3 ka in the middle part of the sedimentary rock and older than 50 ka in the deep part of the granite the evolution processes of these groundwaters were inferred to be water rock interactions such as weathering of plagioclase dissolution of marine sulphate sulphide minerals and carbonate minerals in the na ca hco 3 type of groundwater and mixing between low salinity water in the shallow part and higher salinity water in the deeper part of the granite in the na ca cl type of groundwater the source of salinity in the deeper part of the granite was possibly a palaeo hydrothermal water or a fossil seawater that recharged in the miocene subsequently being modified by long term water rock interaction the cl depth trend in granitic groundwater changes at a depth of 400 m below sea level the hydrogeological properties controlling the groundwater flow and or mixing processes such as advection and diffusion were inferred to be different at this depth in the granite this hydrochemical conceptual model is indispensable not only when constructing the numerical model for evaluating the hydrochemical disturbance during construction and operation of the miu facility but also when confirming a hydrogeological model

deep structural heterogeneities and the tectonic evolution of the abruzzi region central apennines italy revealed by microseismicity seismic tomography and teleseismic receiver functions abstract the crustal structure of central apennines italy is still poorly defined leaving uncertainties on the tectonic style thin or thick skinned responsible for the development of the thrust and fold belt the today active extension which replaced compression since early quaternary is presumably influenced by the pre existing structure that yields location and segmentation of the fault system to focus on such issues we computed p and s wave velocity models of the crust by using the independent methodologies of local earthquakes tomography and teleseismic receiver function we document strong lateral and vertical heterogeneities that define shallow imbricate sheets of the mesozoic cover that overlay exceptionally high vp and high vs bodies these bodies can be interpreted as either dolomitic or partially hydrated mafic rocks the two alternative interpretations respectively imply an ultra thick deposition of dolomitic rocks in the hanging wall of triassic normal fault or a deep exhumation of the pre mesozoic basement during the early mesozoic sin rift tectonic in both cases these bodies influenced the evolution of the thrust and fold belt very remarkably active normal faults like those ruptured during the still ongoing 2009 l aquila sequence concentrate at the border of these bodies suggesting that they have an active role in the segmentation of the normal fault system the rheological behavior of such high vp high vs bodies weak or strong is still uncertain but of utmost importance to understand the risk of future normal faulting earthquakes

geometry segmentation pattern and displacement variations along a major apennine thrust zone central italy abstract hundreds of kilometres long arc shaped continuous thrust faults commonly imply very large displacements by detachment dominated thrusting therefore their occurrence has a large impact on fold thrust belt structure one of the major thrust faults of the central northern apennines the umbria marche sabina thrust zone is traditionally believed to represent one such feature characterised by displacements of several tens of kilometres however detailed studies of this structure revealed that it is actually composed of a series of partially overlapping fault segments rather than consisting of a single continuous thrust cross section balancing and restoration carried out by the integration of surface geological data with available sub surface information points out relatively limited amounts of thrust displacement

carbon 14 study of groundwater in the sedimentary rocks at the tono study site central japan isotopic investigations using 14c of groundwater were carried out to understand the hydraulic conditions in the sedimentary rocks at the tono study site central japan 14c activities of groundwater observed range from 2 to 32 modern carbon pmc measured 14c activities of groundwater are corrected by the isotopic mass balance model based on 14c activities 13c values concentrations of the dissolved inorganic carbon dic and 13c values of non active carbon dissolved into the groundwater from carbonate minerals and organics assuming that the groundwater reservoir is comparable to the piston flow situation the relative 14c ages of groundwaters were calculated from the corrected 14c activity the relative 14c age suggests that the groundwater infiltration from the upper part of the sedimentary rocks to the lower part takes several thousands of years or that the groundwater in the lower part of sedimentary rocks is derived from long distance flow from the surface through the unconformity between the sedimentary rocks and basement granite the flow rate calculated by relative 14c ages shows similar values to those estimated by computer simulation using hydraulic pressure and conductivity data hydraulic conditions at the tono study site inferred from 14c activity agree with those suggested from hydrogeological analyses isotopic approaches using 14c activity can be applied as geochemical evaluation for interpretations from the hydraulic study

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

geomorphological evidence for anti apennine faults in the umbro marchean apennines and in the peri adriatic basin italy abstract the apennines are a relatively recent mountain chain which has been affected by uplift movements since the upper pliocene in fact the remnants of an erosional surface reduced close to base level is preserved at the top of the relief there is no general agreement on the geodynamic stress field and mechanisms which are creating the chain however it is largely accepted that uplift occurred together with the activation on the western side of the chain of extensive faults oriented in the apennine direction nw se which have been linked to the opening of the tyrrhenian sea a great debate is going on about the presence and significance of anti apennine faults ne sw which have been observed by some authors but completely denied by others the main evidence is represented by 1 block faulting of the remnants of the erosional surface along the marchean ridge more elevated relief delimiting relatively depressed areas was created in correspondence with the sibillini mts and mt s vicino similar evidence has been found in the umbro marchean ridge locally more than 1500 metres of displacement have been observed between more and less uplifted remnants 2 block faulting of fan deltas and related beaches of sicilian to crotonian age with more elevated sediments preserved between the tronto and tenna rivers and between the musone and esino rivers maximum displacement along a transect parallel to the coast is 200 metres 3 fault scarps affecting the middle pleistocene river terraces as observed along the esino the tronto the chienti and the tenna river valleys maximum displacements are in the order of 50 metres 4 faulting of horizontal karst galleries and reorientation of the cave network as in the frasassi gorge maximum displacements are about 100 metres 5 captures and alignments in the drainage network of the main river courses 6 large scale gravitational movements as in the ancona landslide and along the chienti and esino rivers their activation occurred in most cases after the lower pleistocene and although their displacements may be of relatively limited extent dispite their recent activity they played a major role in the modelling of the landscape these faults display transtensive extensional and trascurrent movements apart from the controversial geodynamic significance of these faults from a geomorphological point of view they must be considered transverse elements of the stress field from blocks more or less uplifted along the apennine chain the importance and timing of activity of these faults in the quaternary geomorphological evolution of the umbria marchean apennines is demonstrated using evidence usually underestimated by structural geologists which can contribute to a debate based on a multidisciplinary approach

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

linking structures with the genesis and activity of mud volcanoes examples from emilia and marche northern apennines italy mud volcanism is known to be strictly linked to tectonic structures since they have the ability to trap hydrocarbon and other fluids and eventually induce them to migrate from a deep reservoir e g sited into an anticline core where large overpressures may be generated to the surface a central theme is how fluids can migrate upward and which is the role in this process of near structures i e structures directly controlling the mud volcano system and far structures i e faults located far away from the mud volcano system in this study we investigate the role of both types of structures in the genesis and evolution of mud volcanoes in particular we investigate six mud volcano case studies from the emilia romagna and marche pede apennine margin in italy through integration of fieldwork interpretation of available seismic reflection profiles and aerial photos the results of these analyses support an intimate link of the investigated mud volcanoes with anticline structures we discuss two different fluid migration settings particularly i mud volcanoes emplaced on outcropping anticlines and ii mud volcanoes located on top of buried structures discerning when fluids are likely to exploit anticline related fracture sets or secondary structures and porosity finally we speculate on how far structures via the seismic triggering may play a role in the occurrence of historical eruption of some of the investigated mud volcanoes

chlorine 36 dating of very old groundwater 1 the great artesian basin australia chlorine 36 has many advantages as a dating tool for very old groundwater these advantages include a suitable half life 3 01 x 10 sup 5 years simple geochemistry conservative behavior in groundwater and a general absence of subsurface sources at levels comparable to the atmospheric input recent advances in tandem accelerator mass spectrometry have permitted the analysis of sup 36 cl at low abundance expected following residence in the subsurface for 10 sup 6 years or more in order to test the suitability of sup 36 cl for dating very old groundwater the sup 36 cl cl ratios of 26 groundwater samples from the great artesian basin of australia have been measured groundwater ages calculated from the sup 36 cl data compare favorably with ages computed independently from hydrodynamic simulations

cesi an early middle pleistocene site in the colfiorito basin umbro marchean apennine central italy near the village of cesi at the head of the chienti river in the colfiorito basin umbro marchean apennines central italy fluvio lacustrine deposits have yielded mammal fossil remains the results of a multidisciplinary investigation indicate that the vertebrate bearing sediments date about 700 ka and accordingly provide a fossil assemblage for the middle late galerian palynological investigations carried out from sediments underlying the fossiliferous level suggest predominantly cold and dry conditions whereas the fauna suggests a slight climatic amelioration towards cool and moist conditions in the uppermost part of the sequence 1997 john wiley sons ltd

abundance of smectite and the location of a plate boundary fault barbados accretionary prism isolating the respective roles of factors responsible for the initiation and localization of fault zones remains one of the more important goals of research in neotectonics the frontal decollement zone of the northern barbados accretionary prism provides several important clues as to how the interwoven variables of clay mineralogy fluid flow chemical interactions and sediment physical properties affect strain localization this plate boundary fault is centered at a lithologic contact between miocene claystone and fine grained oligocene turbidites the fault zone is nearly 40 m thick at ocean drilling program site 948 and its upper part passes through smectite rich deposits a sharp minimum in percent smectite and a maximum in percent illite mark the base of the decollement there is a consistent increase in percent smectite with distance above the base of the decollement but the top of the decollement is poorly defined by clay mineralogy the intrinsic mechanical weakness of strata with abundant smectite group clays probably influences where the fault tip propagates into the undeformed stratigraphy of the atlantic abyssal plain a second inherited parameter is the local abundance of radiolarians which contribute to higher than normal porosities sediment shear strength also decreases because pore pressure within the fault zone is significantly greater than hydrostatic the principal cause of excess pore pressure seems to be updip fluid advection in theory however decreases in pore fluid salinity and porosity collapse should increase the amount of physicochemical stress generated by expandable clay minerals the imported fluid is unusually low in salinity because it has migrated from zones of deeper seated dehydration reactions if fresher pore water migrates to the propagating tip of the decollement its arrival should increase smectite swelling and reduce the shear strength of the mudstone even more the location and evolution of the decollement therefore are controlled by a complicated interplay of static factors inherited from the abyssal atlantic stratigraphy and dynamic factors associated with episodic fluid flow and changing fluid chemistry

anisotropic seismic structure of the lithosphere beneath the adriatic coast of italy constrained with mode converted body waves received 7 may 2002 revised 26 august 2002 accepted 3 september 2002 published 26 november 2002 1 ps converted waves observed near ancona on the adriatic coast of central italy as revealed by teleseismic receiver functions rfs vary with earthquake backazimuth and epicentral distance in a manner consistent with a 1 d anisotropic seismic structure using reflectivity calculations we develop a profile of anisotropic seismic velocity through the adriatic lithosphere at this locality we infer crustal thickness of 45 km anisotropy within the crust appears at 15 km depth suggesting a decollement between the subducting adriatic lithosphere and the overriding crustal wedge lineation of inferred rock fabric is compatible with simple shear in ene wsw direction in the upper mantle we infer an anisotropic layer at 80 90 km depth if caused by olivine crystals alignment the nearly north south lineation of the inferred rock fabric would be consistent with some nearby shear wave splitting observations this anisotropic layer may be related to mantle deformation induced by the rollback of adriatic lithosphere index terms 7203 seismology body wave propagation 7218 seismology lithosphere and upper mantle 8102 tectonophysics continental contractional orogenic belts citation levin v l margheriti j park and a amato anisotropic seismic structure of the lithosphere beneath the adriatic coast of italy constrained with mode converted body waves geophys res let t 29 22 2058 doi 10 1029 2002gl015438 2002

the colle curti mammal site in the colfiorito area umbria marchean apennine italy geomorphology stratigraphy paleomagnetism and palynology abstract an approximately 90 m thick sequence has been studied in the colle curti basin colfiorito area umbria marchean apennine it was deposited in a drainage system characterized by a mature landscape without a clear watershed separating the adriatic and tyrrhenian sides close to the end of the early pleistocene this landscape was dismembered by the activation of extensional faults linked to an uplifting of the chain that reached its greatest magnitude at the beginning of the middle pleistocene from a sedimentological point of view the sequence can be roughly divided into three parts with gravel deposition in a braidplain environment dominating the lower and upper parts and a phase of clay deposition in a lacustrine environment separating these an ar ar analysis on the sanidine contained in a vertisol in the upper part of the sequence gave an age not older than 427 ka an early galerian fauna was collected in clay layers where the jaramillo paleomagnetic event was recognized cold periods are documented in the lower and upper part of the sequence although in the latter the intense weathering caused by the development of a soil with tropical features precludes further investigations the palynological data supported by sedimentological and palaeomagnetic evidence indicate that the sequence can be related to a large part of the bavelian and part of the menapian in the middle part where clay layers outcrop two cool and humid phases are followed by colder and drier periods biological and geological evidence suggests that around 1 my the basin of colle curti was probably located at an elevation of about 600 m

can seismic waves be trapped inside an inactive fault zone the case study of nocera umbra central italy in march 1998 a small aperture 350 m linear array of five broadband stations was installed across a pliocene strike slip fault crossing the town of nocera umbra central italy three component seismograms of local earthquakes recorded during the umbria marche seismic sequence have shown that the degradation of mechanical properties in damaged rock causes a significant amplification of ground motion within the fault zone marra et al 2000 during the operation of the array an m w 5 3 subcrustal earthquake occurred at a depth of 48 km and an epicentral distance of 10 km from nocera umbra the near vertical incidence of this event offers a unique opportunity for constraining the 2d geometry of the laterally heterogeneous low velocity structure responsible for the large amplification across the fault based on the observed symmetry of the amplification pattern a 2d wedge shaped model of the fault zone is used for the computation of antiplane sh synthetic waveforms to be compared with observations along the array two parameters of the wedge model can be constrained by independent geophysical and geological data 1 shear wave velocity in pristine rock outside the fault zone v s 2200 m sec and 2 the lateral extent of the damaged rock zone l 160 m the other two model parameters namely the wedge depth h and shear wave velocity of the fault zone v f s are varied computer simulations show that trapped waves which have been observed so far for earthquakes occurring inside the fault zone can develop inside a 2d wedge model when struck by external vertically incident seismic radiation results of numerical modeling indicate that in spite of its extreme simplicity such an idealized model is successful in reproducing many of the essential characters of ground motion within the fault zone of nocera umbra even though the best fit solution is not unique and the model parameters trade off each other a study of parameter sensitivity comparing synthetics with recorded data indicates that the variability of h and v f s can be restricted to a limited range of values the quality of fit is optimal when the shear velocity reduction lies in the range of 40 50 and the depth of the trapping zone is comprised between 1 and 2 km

negative polarity seismic reflections along faults of the oregon accretionary prism indicators of overpressuring either thrusting of higher over lower impedance sediment or reduction of impedance locally in the fault zone can produce negative polarity reflections along the protothrusts and the frontal thrust of the oregon accretionary prism the vertical displacement of protothrusts averages only 27 m is uncorrelated to the occurrence of polarity reversals and is insufficient to generate the impedance contrasts associated with the negative polarity reflections the negative polarity reflections from the protothrusts are probably due to localized impedance reduction in the fault zone waveform modeling of these negative polarity reflections indicates they develop due to a single interface with negative impedance contrast this seismic signal could be produced by a fault zone with a sharp upper boundary with low impedance fault material and a transition down section to sediment of higher impedance an impedance inversion due to the 1 km throw on the frontal thrust could create the observed negative polarity reflections interval velocities do not decrease across the frontal thrust but core scale velocity measurements indicate a velocity decrease in the frontal thrust therefore the negative polarity reflections are apparently produced by a localized decrease in impedance waveform modeling of frontal thrust reflections suggests the low impedance interval is about 20 m thick with discrete upper and lower boundaries moderately dipping faults are an efficient path for fluid expulsion across the turbidites with low equivalent vertical permeability fluid migration from the over pressured section up the faults can locally reduce the velocity sufficiently to cause the negative polarity reflections

analysis of mountain springs discharge time series in the tennacola stream catchment central apennine italy the mountain portion of the tennacola stream basin which is located in the northeast sector of the sibillini mountains central apennines italy has a large number of springs exploited for drinking water the presence of lithotypes with different hydraulic conductivity allowed the formation of two main groups of springs with different discharge and regime this paper aims to provide new insights about the groundwater circulation within carbonate and karst complexes in detail a study based on spring hydrograph analysis using the mrc method and on the main statistical parameters has been carried out in order to evaluate the main features related to the flow paths and the main hydrogeological properties of the aquifers studied the results allowed to characterize the main hydrogeological features of the aquifers and to evaluate the dimension of the recharge areas

late quaternary geomorphological evolution and erosion rates in the clayey peri adriatic belt central italy abstract this study analyses the geomorphological evolution during the last 20 000 years in two areas representative of the peri adriatic belt of central italy mt ascensione in the high hilly sector 600 1100 m a s l and the atri district in the hilly coastal sector up to ca 500 m a s l in both areas the lithostructural setting is characterized by an east verging monocline mainly composed of clayey formations the two areas are compared in relation to their morpho chronological aspects and geomorphological dynamics the results suggest two fundamental evolutionary phases 1 about 20 000 yr bp sedimentation occurred along the main valleys when the middle to upper portions of slopes were covered by colluvial deposits and 2 at the beginning of the holocene the climatic improvement triggered erosion along rivers producing deep and narrow valleys estimated denudation rates during the last 20 000 yr are 7 8 mm yr 1 for the mt ascensione area and 2 4 3 0 mm yr 1 for the atri district reflecting frequent landslides and fluvial erosion the rates are consistent with the data available in literature denudation rates double if we assume most of the erosion process took place after the beginning of the holocenic warming phase

fault fragment control in the 1997 umbria marche central italy earthquake sequence the umbria marche region in central italy experienced a sequence of shallow earthquakes in late 1997 including three mainshocks on september 26th ms 5 5 and 5 9 and october 14th ms 5 5 this seismic sequence illustrates the relationships between small scale active faults and moderate magnitude earthquakes we suggest that a small scale active fault corresponds to a fault fragment and that it refers to the fault area required for producing a coseismic deformation at the ground surface the seismic activity and related three mainshocks occurred along three fault fragments which total 25 km in length and show a listric geometry at depth fault fragments are laterally controlled by pre existing transverse fold and thrust structures and may constitute a major component of the seismic strain release in active continental regions

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

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

three dimensional visualization of the neogene structures of an external sector of the northern apennines italy a three dimensional 3 d visualization technique is used to build a structural model linking a complex series of thrust sheets in an external area of the northern apennines central italy this foreland fold and thrust belt consists of faulted anticlines and broad syn clines involving a triassic paleogene succession that is detached from the underlying basement reactivation of basement faults has influenced the geometry and kinematics of the overlying structures in a mix of thin skinned and thick skinned tectonics upper de tachment horizons within the sedimentary succession form shallow structures in the crestal zone of the major anticlines all the struc tures are scantily cylindrical and the model demonstrates the soft linkages between oblique and frontal structures through relay ramps

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

vp and vp vs images in the mw 6 0 colfiorito fault region central italy a contribution to the understanding of seismotectonic and seismogenic processes 1 in 1997 the umbria marche apennines central italy was struck by a series of moderate magnitude normal faulting earthquakes accompanied by a prolonged sequence of aftershocks seismological analysis revealed a 40 km long nw trending structure composed by several low angle normal fault segments in this paper we present the three dimensional 3 d vp and vp vs structure of the fault zone determined by the inversion of p and s wave arrival times from 1982 aftershocks the high resolution tomographic images reveal strong heterogeneity along and across the fault zone and allow us along with the 3 d location of earthquakes to define the fault geometry at depth and to improve our understanding on the seismotectonics of this part of the northern apennines thrust and fold belt the relocated aftershocks suggest that the main ruptures occurred on planes slightly steeper than previously hypothesized and at depths shallower than those evidenced by 1 d locations we find that the preexisting structure which developed during the neogene compressional tectonics plays an important role in the earthquake generation and rupture evolution of the normal faulting events we propose that the main shocks whose hypocenters are all located at 6 km depth originated along a shallow decollement of the meso cenozoic cover thrust over the metamorphic basement geometrical discontinuities and lateral steps along the inherited structures control the lateral fault extent and determine fault segmentation this study offers a good example of how lithological heterogeneities and the complexity of the upper crust structure strongly affect the faulting process

potassium and boron co depletion in canadian shield brines evidence for diagenetic interactions between marine brines and basin sediments abstract hypersaline ca cl brines of marine origin deep within the crystalline rocks of the canadian shield are typically highly depleted in potassium and boron compared to their concentrated seawater parent brine while this depletion in both solutes is not accompanied by a major alteration in their original marine b k ratios their initial marine 11 b has been lowered to 20 30 values that are intermediate between that of present day seawater 39 and typical crustal values 3 5 together these observations eliminate 3 of 4 potential k and b removal mechanisms that may have operated at various times over the long history of shield brines 1 co precipitation in late stage evaporative salts in the marine basin where the brine was formed 2 incorporation in secondary feldspars formed either within basin sediments or the host rocks and 3 in situ adsorption by secondary clay minerals on fracture surfaces rather the 11 b values together with the consistency in the depleted but similar k br and b br ratios suggest that k and b were removed from shield brines by fixation in illitic clay minerals this likely occurred during the diagenetic illitization of smectite in argillaceous marine sediments through which the brine infiltrated prior to penetrating the underlying crystalline basement rocks

cross checking groundwater age by 4he and 14c dating in a granite tono area central japan abstract groundwater dating was performed simultaneously by the 4he and 14c methods in granite of the tono area in central japan groundwater was sampled at 30 packed off sections of six 1000 m boreholes 4he concentrations increased and 14c concentrations decreased along a groundwater flow path on a topographic gradient 4he ages were calculated by using the in situ 4he production rate derived from the porosity density and u and th content of the rock neglecting external flux 14c ages were calculated with a noncorrected model in which the initial 14c content was 100 percent of the modern radiocarbon level co 100 pmc a statistical model using the average 14c content of tritium bearing samples co 46 4 pmc and a 13c model based on the isotopic mass balance although the absolute 14c ages calculated by the models were different the relative 14c ages were almost identical the relative 14c ages were considered reliable because dissolved inorganic carbon has no significant geochemical reactions in granite the relation between the 4he ages and the noncorrected 14c ages was 4he age 1 15 14c age 7200 r2 0 81 except in the discharge area the slope of this relation was equivalent to unity which indicates that the 4he accumulation rate is confirmed by the relative 14c ages moreover the accumulated 3he 4he ratio was equivalent to that derived from the 6li n 3h reaction in granite these results show that the accumulated he is of crustal origin produced in situ without external flux except in the discharge area the intercept value of 7200 a implies that the 14c concentrations were diluted due to geochemical reactions tritium bearing samples supported this result simultaneous measurements make it feasible to estimate the accumulation rate of 4he and initial dilution of 14c which cannot be done with a single method cross checking groundwater dating has the potential to provide more reliable groundwater ages the circulation time of the groundwater flow in the tono area may be several tens of thousands of years and the groundwater age calculated from the 4he and 14c ages appears to be consistent with geochemical information such as groundwater types d and 18o

groundwater dating by estimation of groundwater flow velocity and dissolved 4he accumulation rate calibrated by 36cl in the great artesian basin australia abstract we tested two methods for dating groundwaters that cannot be reliably measured by 36cl dating alone one based on groundwater flow velocity plus distance along a flow path and the other based on 4he accumulation rates calibrated with 36cl dates we sampled groundwaters along six inferred regional groundwater flow paths in the great artesian basin gab of australia we selected three groundwater paths where the decrease in 36cl was largely controlled by cosmogenic 36cl radioactive decay without a significant increase in chloride concentration the extrapolated groundwater velocities were 0 133 0 018 m y to 0 433 0 140 m y the estimated residence time of 1 06 106 y at the discharge area around lake eyre was comparable to the estimate of 1 2 2 106 y in previous studies on the other hand our estimated 4he accumulation rates for the selected three groundwater flow paths 1 85 0 31 10 11 to 1 51 0 63 10 10 ccstp cm3 y were approximately 2 15 times lower than previously reported rates for the central gab our estimated rate of 1 51 10 10 ccstp cm3 y 1 in the western gab is compatible with previous estimates based on 81kr ages the groundwater residence time estimated from the 4he accumulation rate was approximately 7 105 y near the discharge area at lake eyre finally both estimations were mutually compatible with a 30 error

a classification of thrust fronts variations in structural style at thrust fronts are examined to determine whether they represent different stages of typical thrust sheet development or unique events as orogenic stresses declined thrust fronts are classified as buried or emergent in which either the sole thrust died out in the subsurface or emerged to the synorogenic surface buried thrust fronts are subdivided into two types type 1 fronts end in broad zones of low strain type 2 fronts end in zones of high strain emergent thrust fronts may display significant horizontal displacement strongly emergent or limited displacements of about 1 km weakly emergent tip stick thrust fronts exhibit high strains and out of sequence thrusting different types of thrust fronts are linked by transitional tip li e anticlines and strike slip zones most thrust front types represent different stages of typical thrust sheet development but those in type 1 display atypical development unique to thrust fronts