the origin and evolution of canadian shield brines evaporation or freezing of seawater new lithium isotope and geochemical evidence from the slave craton abstract new chemical and isotopic data for deep seated calcium chloride brine from the miramar con gold mine yellowknife n w t strongly suggest that the brine salinity is of marine origin diagnostic marine properties include uniformly elevated br cl ratios typical of seawater concentrated beyond halite saturation and li br ratios 0 0254 0 0325 and 6 li compositions 32 1 to 36 3 similar to seawater 32 3 the mean 6 li for all mine water samples of 35 1 may reflect minor uptake of li by secondary minerals this interpretation is supported by analyses of altered metabasalt from fault zones which is enriched in li but depleted in 6 li 14 7 to 15 6 relative to the unaltered metabasalt 5 4 the mechanism responsible for concentrating the hypersaline brine end member is not unequivocal as evidence exists to support both evaporative and cryogenic processes on the one hand the devonian sedimentary record in the great slave lake region in conjunction with yellowknife brine isotopic compositions 2 h and 34 s so 4 that are similar to various devonian fluids support an evaporative origin on the other hand the na cl br cl relationship in the brine strongly suggests a cryogenic mechanism regardless of the concentrative mechanism the chemical data indicate that the yellowknife parent brine was concentrated 28 to 30 fold relative to seawater the extreme depletion of mg and enrichment of ca in the brines accompanied by sr ca ratios similar to that of seawater are accounted for by dolomitization of an aragonite rich marine sediment by the brine before infiltration into the crystalline basement rocks subsequent alteration of silicate minerals in the shield added additional ca and sr to the brine as indicated by their radiogenic 87 sr 86 sr ratios up to 0 7147 based on mineral balance calculations the major mineral products of the cryogenic and evaporitic concentration and evolution paths are significantly different the cryogenic evolution results in some 15 mirabilite 60 hydrohalite and 18 dolomite whereas the major minerals formed from the evaporitic evolutionary sequence are 36 halite 8 gypsum 17 dolomite and 30 albite the great similarity between the calcium chloride brine from yellowknife and other such canadian shield brines indicates that they may share a common marine origin

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

multifrequency full waveform sonic logging in the screened interval of a large diameter production well abstracta set of field experiments using multiple transmitter center frequencies was completed to test the application potential of low frequency full waveform sonic logging in large diameter production wells wireline logs were acquired in a simple open drillhole and a high yield large diameter production well completed with wire wound sand screens at an aquifer storage and recovery site in perth western australia phase shift transform methods were applied to obtain phase velocity dispersion images for frequencies of up to 4 khz a 3d representation of phase velocity dispersion was developed to assist in the analysis of possible connections between low frequency wave propagation modes and the distribution of hydraulic properties for sandstone intervals in the test well the highest hydraulic conductivity intervals were typically correlated with the lowest phase velocities the main characteristics of dispersion images obtained from the sand screened well were highly comparable with those obtained at t

estimating phase velocity and attenuation of guided waves in acoustic logging data in acoustic logging the guided waves which propagate along the borehole are affected by the properties of the formation for acoustic logging tools with many receivers array processing methods can be used to calculate the phase velocity and attenuation of these waves this information is crucial in estimating formation properties like permeability transverse isotropy and s wave velocity

stoneley wave propagation in a fluid filled borehole with a vertical fracture the propagation of stoneley waves in a fluid filled borehole with a vertical fracture is investigated both theoretically and experimentally the borehole propagation excites fluid motion in the fracture and the resulting fluid flow at the fracture opening perturbs the fluid solid interface boundary condition at the borehole wall by developing a boundary condition perturbation technique for the borehole situation we studied the effect of this change in the boundary condition on the stoneley propagation cases of both hard and soft formations have been investigated the fracture has minimal effects on the stoneley velocity except in the very low frequency range in which the stoneley velocity drastically decreases with decreasing frequency significant stoneley wave attenuation is produced because of the energy dissipation into the fracture the quantitative behavior of these effects depends not only on fracture aperture and borehole radius but also on the acoustic properties of the formation and fluid

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

neogene patterns of relative plate motion for africa europe some implications for recent central mediterranean tectonics a detailed relative motion picture for the neogene africa europe plate kinematics is presented the kinematic reconstruction was carried out using the finite difference solution between the rotation parameters determined for anomalies 7 to 2 in the africa north america europe plate motion circuit the analysis shows a motion of africa with respect to europe which is nne directed during late oligocene to burdigalian times becoming nnw trending from the langhian to the early tortonian from upper tortonian times onward the motion changes to a clear north west directed convergence major late neogene tectonic features of the central mediterranean region can to a large extent be explained within the context of the reconstructed major plate motions late tortonian to recent africa europe slip vectors are compatible with a variety of geological phenomenoa such as north west directed subduction beneath calabria south east translation of calabria and extension in the tyrrhenian sea north west trending slip vectors from thrust earthquakes between gibraltar and sicily and dextral strike slip across the north african margin

effects of in situ permeability on the propagation of stoneley tube waves in a borehole we investigated the theoretical relationship between propagation characteristics of stoneley tube waves in a borehole and in situ permeability by using a modified formulation of a borehole model with a formation that behaves as a biot porous medium we found that stoneley wave attenuation and phase velocity dispersion increased with increasing permeability and porosity and decreased with increasing frequency in rocks with low to medium permeabilities less than 100 md variations in formation velocity and attentuation were major contributors to variations in stoneley wave properties at normal logging frequencies however in high permeability rocks greater than 100 md coupling between the borehole and pore fluids associated with in situ permeability was more important than lithological changes in controlling stoneley wave properties pore fluid viscosity had an effect on stoneley wave propagation equal but opposite to permeability and hence must he taken into account we compared our theoretical

thrust tectonics thin skinned or thick skinned and the continuation of thrusts to deep in the crust abstract the paper analyses the geometry of thin skinned thrust zones where the thrusts shallow out at depth and of thicker skinned fault zones where much of the crust is involved and where the thrusts are frequently observed to become steeper downwards in the interiors of many orogenic belts the steep dip of faults is not original but due to the folding above lower decoupling zones the energy involved in the internal deformation of hanging wall rocks may prohibit many faults becoming more shallow upwards such shallowing upwards faults may occur in more ductile rocks to maintain compatibility between zones which have experienced different deformation intensities but displacements on the faults are unlikely to be large another mechanism for producing faults which steepen downwards is proposed for the major thrusts which form the southern margin to the himalayas these carry large thicknesses 30 to 100 km of crustal and upper mantle rocks to the south causing flexuring and isostatic depression of the indian plate the steeply dipping thrusts are not footwall ramps these may be some distance behind the steepened zone this thrust induced isostatic bending of the crust has important implications when considering regional seismic interpretations as well as thrust mechanics and kinematics

deriving thrust fault slip rates from geological modeling examples from the marche coastal and offshore contraction belt northern apennines italy abstract we present a reconstruction of the central marche thrust system in the central northern adriatic domain aimed at constraining the geometry of the active faults deemed to be potential sources of moderate to large earthquakes in this region and at evaluating their long term slip rates this system of contractional structures is associated with fault propagation folds outcropping along the coast or buried in the offshore that have been active at least since about 3 myr the ongoing deformation of the coastal and offshore marche thrust system is associated with moderate historical and instrumental seismicity and recorded in sedimentary and geomorphic features in this study we use subsurface data coming from both published and original sources these comprise cross sections seismic lines subsurface maps and borehole data to constrain geometrically coherent local 3d geological models with particular focus on the pliocene and pleistocene units two sections crossing five main faults and correlative anticlines are extracted to calculate slip rates on the driving thrust faults our slip rate calculation procedure includes a the assessment of the onset time which is based on the sedimentary and structural architecture b the decompaction of clastic units where necessary and c the restoration of the slip on the fault planes the assessment of the differential compaction history of clastic rocks eliminates the effects of compaction induced subsidence which determine unwanted overestimation of slip rates to restore the displacement along the analyzed structures we use two different methods on the basis of the deformation style the fault parallel flow algorithm for faulted horizons and the trishear algorithm for fault propagation folds the time of fault onset ranges between 5 3 and 2 2 myr overall the average slip rates of the various thrusts are in the range of 0 26 1 35 mm yr

application of the maximum likelihood method mlm for sonic velocity logging modern digital sonic tools can record full waveforms using an array of receivers the recorded waveforms are extremely complicated because wave components overlap in time conventional beamforming approaches such as semblance processing while robust sometimes do not resolve the interfering wave components propagating at similar speeds such as multiple compressional arrivals due to the formation alteration surrounding the borehole here the maximum likelihood method mlm a high resolution array processing algorithm is modified and applied to process borehole array sonic data extensive modifications of the original mlm algorithm were necessary because of the transient character of the sonic data and its effect upon the spectral covariance matrix we applied mlm to several array sonic data sets including laboratory data synthetic waveforms and field data taken by a schlumberger array sonic tool mlm s slowness resolution is demonstrated in resolving a secondary compressional arrival from the prima

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

introduction to the thematic collection apennines tyrrhenian system the geodynamic evolution of the apennines and tyrrhenian sea is the object of controversial interpretations and scientific discussion with important consequences for the overall tectonic evolution of the mediterranean area from tertiary to recent times different interpretations stem from the geological complexity of this region where recent and still active extensional tectonics strongly overprint previous pre and syn orogenic structural features that are connected to the early evolution of the area in the last decades contributions towards a better understanding of this subject derive from geophysical petrologic geochemical magmatic tectonic and sedimentary studies which addressed the reconstruction of geological processes leading to the pre syn and post orogenic evolution of the apennine belt and surrounding areas this thematic collection collates papers presenting results from latest research on the evolution and structure of the apennines that was presented in the thematic session ts 7 13 gd 8 7 gmpv 9 2 ssp 2 16 the apennines tyrrhenian system multidisciplinary contributions to the understanding of the tectonic setting magmatism and geodynamic evolution at egu2018 meeting

the role of seawater freezing in the formation of subsurface brines abstract several mechanisms evaporation water rock interaction ultra filtration have been suggested to explain the evolution of ubiquitous ca chloride subsurface brines in the present paper the freezing of seawater in polar regions and in even wider areas during glacial periods is proposed as an additional possible path of brine formation four detailed seawater freezing experiments to 14 c resulting in a concentration factor of about 5 were carried out and na k ca mg sr cl so4 and br were analysed in the residual brines and in the ice br and sr whose behavior during the freezing of seawater is reported here for the first time show a conservative behavior throughout the studied temperature range our data and earlier literature show that the high salinities which are common in subsurface brines 300 g l may be obtained by the removal of h2o as ice in the primary glacial environment the decrease in the na cl ratio is caused by the crystallization of mirabilite na2so4 10h2o supplemented by hydrohalite nacl 2h2o sulfate is removed both in mirabilite and by bacterial reduction the brine then migrates to the subsurface heats up under the local geothermal gradient and interacts with the adjacent rocks at this stage it may be diluted by meteoric waters its mg ca ratio decreases dolomitization and chloritization the so 4 cl ratio varies according to the local gypsum anhydrite equilibrium conditions and the ca so 4 hco 3 ratio increases as a result of dolomitization or chloritization the interaction with rocks in the subsurface may affect both the original 87 sr 86 sr and the 18 o 16 o ratios of the brine although several of the processes which lead to the formation of ca chloride brines are common for both the evaporative and the freezing models the na br cl relationship in a given brine can be used to discriminate between the two modes of brine evolution several subsurface brines from the canadian shield and one brine from finland are used as examples of the seawater freezing model and an explanation is proposed for the necessary mass production of brines in glacial environments

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

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

tectonic history of the western tethys since the late triassic the tectonic history of the western tethys since the late triassic is illustrated through a set of computer generated plate reconstructions which are based on a rigorous plate motions model of this region the model is constrained by the atlantic plate kinematics and on land geologic evidence and defines 13 tectonic phases spanning the time interval from the late ladinian 230 ma to the present the kinematics associated with the late triassic western tethyan rifts produced the detachment of a large composite fragment from the northern margin of gondwana it can be considered as the eastern propagation of the central pangea breakup during the early jurassic these rift zones became inactive while new zones of extension formed along the southern margin of eurasia the eastern margin of iberia and within the rifted northern gondwana fragment itself plate motions associated with the first two extensional centers can still be considered as an eastern branch of the central atlantic plate kinematics conversely the kinematic parameters of the latter rift result from the composition of the euler rotation describing the central pangea breakup and the euler pole of closure of the paleo tethys ocean the late triassic early jurassic rifting phases determined the formation of a number of independent microplates at the interface between africa and eurasia starting from the early cretaceous convergence between africa and eurasia triggered further deformation within the dispersed continental fragments and the formation of backarc basins at the active margins ultimately leading to an increase in the number of tectonic elements that were moving independently in the western tethyan region during the late cretaceous and the cenozoic the proposed tectonic evolution of the western tethys area is compatible with both global scale plate kinematics and geological constraints from on land data observed across the present day mosaic of displaced terranes surrounding the mediterranean region

iodine 129 constraints on residence times of deep marine brines in the canadian shield canadian shield brines are characterized by high concentrations of both stable iodine and 1 2 9 i the former reflecting its concentrated but diagenetically modified seawater origin and the latter its long subsurface residence time within its host shield rocks stable iodine concentrations in the yellowknife brine are as high as 18 mg l requiring the contribution of iodine from an external marine reservoir this reservoir likely comprised organic rich marine sediments in the basin where the brine was produced diagenesis of these sediments released iodine to the brine during its infiltration into the subsurface 1 2 9 i concentrations in the yellowknife brine are as high as 3 4 x 10 8 atom l and are due to the fission of 2 3 8 u in the rock matrix and subsequent diffusion of the radiogenic 1 2 9 i into the fracture fluids this concentration is close to the predicted secular equilibrium concentration for a fluid in basaltic rock with a uranium concentration of 1 mg kg after the residence time of 80 m y required for secular equilibrium has been attained this time period is interpreted as the minimum residence time of the yellowknife brine in the shield but it may be much greater possibly dating back to middle devonian time when most of the present day shield was covered by seawater similarly high stable iodine and 1 2 9 i concentrations measured in the sudbury brine support a generic ancient marine hypothesis for the origin of shield brines stable iodine and 1 2 9 i concentrations in the shallower mine waters are the result of mixing between the brine and low iodine modern meteoric recharge that is enriched in 1 2 9 i due to global fallout from nuclear fuel waste reprocessing activities

estimating slowness dispersion from arrays of sonic logging waveforms acoustic wave propagation in a fluid filled borehole is affected by the type of rock which surrounds the hole more specifically the slowness dispersion of the various body wave and borehole modes depends to some extent on the properties of the rock we have developed a technique for estimating the dispersion relations from data acquired by full waveform digital sonic array well logging tools the technique is an extension of earlier work and is based on a variation of the well known prony method of exponential modeling to estimate the spatial wavenumbers at each temporal frequency this variation known as the forward backward method of linear prediction models the spatial propagation by purely real valued wavenumbers the prony exponential model is derived from the physics of borehole acoustics under the assumption that the formation does not vary in the axial or azimuthal dimensions across the aperture of the receiver array but can vary arbitrarily in the radial dimension the exponential model fits

iodine 129 constraints on residence times of deep marine brines in the canadian shield comment and reply bottomley et al 2002 1 present 129i analyses of hypersaline brines from the con gold mine in yellowknife northwest territories the authors assume that the 129i formed by 238u fission within the metabasalt host rocks and diffused from the rock matrix into the fracture fluid explaining its

controls on the 129i i ratio of deep seated marine interstitial fluids old organic versus fissiogenic 129 iodine iodine and its radioisotope 129i have been successfully used to trace the origin of pore waters in submarine fluid escape structures because of their close association with organic material in deeply buried sediments we report here halogen concentrations and 129i i ratios for fluids of five mud volcanoes sampled along an e w transect across the gulf of cadiz in the ne atlantic ocean concentrations of iodide and bromide increase consistently seaward accompanied by a decrease in 129i i ratios from 6490 10 15 to 663 10 15 the exceptionally high 129i i ratios at the near shore locations reflect the presence of fissiogenic 129i produced in situ by spontaneous fission of 238u within terrigenous sediments and released into pore water during clay mineral diagenetic processes the observed 129i i and halogen trends together with similar changes in 87sr 86sr ratios indicate a progressive seaward transition from inorganic terrigenous to organic marine fluid sources comparison of our results with literature data for varying geological settings reveals a general relationship between fissiogenic 129i radiogenic 87sr and the lithology or provenance of rocks and sediments respectively while 129i i ratios in continental rock hosted aquifers and terrigenous sedimentary systems are dominated by in situ production of fissiogenic 129i iodine isotopes in oceanic settings or volcanogenic marine sediments reflect the release of old iodine from deeply buried organic matter the gulf of cadiz represents the full transition between these continental and oceanic 129i i and 87sr 86sr end members this is the first systematic investigation of fissiogenic 129i production in marine sedimentary environments

plio quaternary tectonics and possible implications for geothermal fluids in the marche region italy abstract structural features such as faults and fractures play an important role in fluid circulation within the crust and influence geothermal exchange potential based on this consideration we examined the subsurface structural setting of the marche region central italy in terms of detailed data we obtained on the groundwater in wells detailed analyses of its physical properties particularly electrical conductivity revealed some anomalies in several localities which appear to be related to the local tectonic structures in addition we interpreted data from seismic reflection profiles provided by eni s p a and kindly shared with us for the sw ne area crossing the apennine chain and extending to the adriatic sea our interpretation indicates the presence of important sub surface and deep plio quaternary structures linked to outcropping ones with possible hydrogeological implications our interpretation of these seismic profiles enabled us to identify some high angle structures affecting the whole sedimentary sequence and routed at depth 10 km thus allowing us to gain an understanding of the recent structural evolution of the apennine marche sector we interpreted these mainly nw se trending structures to be transpressive structures related to lower depth sw and ne dipping high angle reverse faults positive flower structures probably involving the upper crust basement we identified them along three main parallel alignments transects from sw to the coastline crossing the mio pliocene apennine range and its external plio quaternary sector our analyses of the groundwater in wells throughout the study area indicated possible relationship with deep geological structures it seems that the high degree of fracturing that accompanies these complex and recent fault systems could facilitate the exchange between superficial and deeper fluids this is supported by the observation that there is a direct relationship between the electrical conductivity of the water in wells located along the calcareous marly apennine marche ridge and the amount of rainfall

a numerical investigation of head waves and leaky modes in fluid filled boreholes although synthetic borehole seismograms can be computed for a wide range of borehole conditions the physical nature of shear and compressional head waves in fluid filled boreholes is poorly understood this paper presents a series of numerical experiments designed to explain the physical mechanisms controlling head wave propagation in boreholes these calculations demonstrate the existence of compressional normal modes equivalent to shear normal modes or pseudo rayleigh waves with sequential cutoff frequencies spaced between the cutoff frequencies for the shear normal modes major contributions to head wave spectra occur in discrete peaks at frequencies just below mode cutoff for both compressional and shear modes this result is confirmed by calculations with synthetic waveforms at frequencies corresponding to mode cutoff and by branch cut integrals designed to yield independent spectra for the compressional mode for soft formations where shear velocity falls below acoustic velocity in the borehole

plio quaternary transpressive tectonics a key factor in the structural evolution of the outer apennine adriatic system italy we used data from seismic reflection profiles and well logs from both onshore and offshore locations along the adriatic coast to investigate the structural style and recent active deformation in the external area of the northern apennines adjoining the po plain we prepared four ne sw sub parallel transects based on a detailed interpretation of the available subsurface data supported by surface geological data through analysis of the well logs we identified two significant seismo stratigraphic markers together with some unconformities within the middle pliocene quaternary succession we propose a detailed structural scheme for the area that identifies and interprets both the outcropping and buried apennine structures nw nnw se sse high angle transpressive or flower structures referred to the recent and actual deformation history may be responsible for surface features and features at shallow depths with possible implications for active tectonics we show the continuity of some of these structures towards the conero area to the south suggesting a wider and more regional meaning for the proposed tectonic style these apenninic structures close against the active nne ssw cattolica fault system in the northern offshore part of the area to form an asymmetrical arch this study contributes to the interpretation of the deformation style of the outer northern apennines supplementary material high resolution seismic lines not interpreted are available at https doi org 10 6084 m9 figshare c 4497542 thematic collection this article is part of the apennines and tyrrhenian system collection available at https www lyellcollection org cc the apennines tyrrhenian system

can we ever trust the shear wave log abstract after three decades of shear wave logging there are still questions on the robustness of the measurement the perceived variability in shear wave slowness measurements comes from two main sources 1 the dispersive nature of the flexural and quadrupole waves used in the measurement and 2 anisotropy dispersion and anisotropy affect shear wave slowness measurements and various methods take those effects into account to obtain a more robust shear wave slowness log

homomorphic processing of the tube wave generated during acoustic logging we have developed a new method to process the tube wave which is generated during acoustic logging to obtain estimates for its wavenumber attenuation coefficient amplitude and phase at every frequency to improve the accuracy of the estimates the method can use data from multiple sources and data collected at successive depths in the borehole this new method has several advantages over other methods that are currently used to process acoustic logging data the new method can obtain accurate estimates of the wavenumber and amplitude from only a few receivers the receivers can be irregularly spaced and no spurious estimates are generated nonetheless this new method has one disadvantage compared to others it can only estimate the parameters for one high amplitude wave like the tube wave also like all other existing methods the new method obtains only reasonable estimates for the attenuation coefficient when data from many receivers are processed

shear velocity logging in slow formations using the stoneley wave we apply an iterative linearized inversion method to stoneley waves recorded on acoustic logs in a borehole our objective is to assess inversion of stoneley wave phase and group velocity as a practical technique for shear velocity logging in slow formations indirect techniques for shear logging are of particular importance in this case because there is no shear head wave arrival acoustic logs from a long spaced sonic tool provided high quality low noise data in the 1 to 10 khz band for this experiment a shear velocity profile estimated by inversion of a 60 ft 18 3 m section of full wave acoustic data correlates well with the p wave log for the section the inferred shear velocity ranges from 60 to 90 percent of the sound velocity of the fluid formal error estimates on the shear velocity are everywhere less than 5 percent moreover application of the same inversion method to synthetic waveforms corroborates these error estimates finally a synthetic acoustic waveform computed from inversion re