interferometric seismic imaging around the active lalor mine in the flin flon greenstone belt canada abstract seismic interferometry which recovers the impulse response of the earth by cross correlation of ambient noise recorded at sets of two receivers has found several applications including the generation of virtual shot gathers for use in seismic reflection processing to evaluate the effectiveness of this passive recording technique in mineral exploration in a hard rock environment 336 receivers recorded 300 h of ambient noise over the volcanogenic massive sulphide deposit of the recently discovered lalor mine in the canadian flin flon greenstone belt a novel time domain beamforming algorithm was developed to search for individual source locations demonstrating that the vast majority of noise originated from the mine and ventilation shafts of the lalor mine the results of the beamforming were utilized in conjunction with frequency wavenumber filtering to remove undesirable mostly monochromatic surface wave noise originating from nearby sources virtual shot gathers were generated along three receiver lines each of which was processed as a separate 2 d reflection line two of the resulting unmigrated reflection profiles are compared against coincident dipmoveout stacked data from a larger coincident 3 d dynamite seismic survey that was also acquired over the lalor mine in 2013 using knowledge of the local geology derived from numerous boreholes coherent events recovered in the passive reflection profiles are inferred to be either spurious arrivals or real reflections some of which can be interpreted in terms of geological contacts indicating the future potential of passive recording surveys in hard rock settings

the quaternary evolution of the gulf of corinth central greece coupling between surface processes and flow in the lower continental crust abstract the gulf of corinth in central greece is an active normal fault zone with particularly clear evidence of isostatic footwall uplift constrained by quaternary marine terraces and hanging wall subsidence and sedimentation it is bounded to the south by a pliocene to early pleistocene sedimentary basin which is now eroding into the gulf previous work has suggested that the relief across this region has increased dramatically since the early pleistocene due to the isostatic response to increased rates of footwall erosion and hanging wall sedimentation it is indeed assumed here that incision accompanying the draw down of global sea level at 0 9 ma during the first major pleistocene glaciation initiated the erosion of the basin south of the gulf of corinth and so abruptly increased the sedimentation rate in the gulf the resulting transient thermal and isostatic response to these changes is modelled with the subsiding depocentre and eroding sediment source coupled by flow in the lower continental crust the subsequent enhancement of relief involving an increase in bathymetry from near zero to 900 m and 500 m of uplift of the eroding land surface in the sediment source is shown to be a direct consequence of this change the model is sensitive to the effective viscosity of the lower crust and can thus resolve this parameter by matching observations a value of 6 1019 pa s is indicated suggesting a viscosity at the moho no greater than 1018 pa s similar transient topographic effects caused by increased rates of sedimentation and erosion are likely to be widespread within the geological record suggesting that this coupling process involving flow in the weak lower crust may be of major geological and geomorphological importance

coastal uplift on active normal faults the eliki fault greece the eliki fault forms part of a system of major normal fault segments that borders the southern margin of the gulf of corinth half graben radiocarbon dating of elevated marine fossils reveals broadly uniform holocene coastal uplift at a time averaged rate of 1 5 mm yr both along the eliki fault and in the transfer zone that separates it from the neighbouring fault segment coseismic uplift increments are considered to account for only a minor part of the 6 m of emergence recorded here in the last 3000 years reappraisal of shoreline data from the perachora peninsula at the eastern end of the gulf of corinth indicates a similar though less rapid 0 7 mm yr pattern of uniform holocene emergence as these holocene coastal records embody both coseismic and interseismic deformation they can be used to characterise long term tectonic strain

reply to comment by rob westaway on late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates

application of 3d seismic techniques to evaluate ore resources in the west wits line goldfield and portions of the west rand goldfield south africa abstractas expensive as 3d seismic reflection surveys are their high cost is justified by improved imaging of certain ore horizons in some of the witwatersrand basin gold mines the merged historical 3d seismic reflection data acquired for kloof and south deep mines forms an integral part of their ventersdorp contact reef mine planning and development programme the recent advances in 3d seismic technology have motivated the reprocessing and reinterpretation of the old data sets using the latest algorithms therefore significantly increasing the signal to noise ratio of the data in particular the prestack time migration technique has provided better stratigraphic and structural imaging in complex faulted areas such as the witwatersrand basin relative to older poststack migration methods interpretation tools such as seismic attributes have been used to identify a number of subtle geologic structures that have direct impact on ore resource evaluation other improvements include more accurate mapping o

high resolution temperature logging in shallow drillholes for the determination of terrestrial heat flow field examples and analysis abstract the first 200 m of the earth s crust is the depth range most investigated by drilling temperature profiles in such shallow drillholes generally show severe influences of groundwater flow therefore they are rarely used for heat flow determinations but regardless how severely the temperature logs are influenced by advective heat transfer the background conductive heat flow signal is still present in the data it is shown how to handle distorted temperature profiles by means of simple one dimensional steady state models the undisturbed background heat flow is estimated by model calculations the comparison of the modelled temperature profiles with the measured logs is a test for the credibility of the modelling approach examples from northwestern switzerland and northwestern turkey with irregular temperature profiles are given for the following situations conductive convective regime with vertical groundwater movement over the entire observation depth vertical flow in a certain layer located between purely conductive layers and water flow inside of the drillhole measured temperature profiles can be approximated by modelling within 0 2 c repeated high precision digital temperature logging is needed to prove the temporal stability of the convective disturbances in order to use steady state models

dynamics of izmit earthquake postseismic deformation and loading of the duzce earthquake hypocenter we have developed dynamic finite element models of izmit earthquake postseismic deformation to evaluate whether this deformation is better explained by afterslip via either velocity strengthening frictional slip or linear viscous creep or by distributed linear viscoelastic relaxation of the lower crust we find that velocity strengthening frictional afterslip driven by coseismic shear stress loading can reproduce time dependent global positioning system data better than either linear viscous creep on a vertical shear zone below the rupture or lower crustal viscoelastic relaxation our best frictional afterslip model fits the main features of postseismic slip inversions in particular high slip patches at and below the hypocenter and on the western karadere segment and limited afterslip west of the hersek delta burgmann et al 2002 the model requires a weakly velocity strengthening fault that is either low effective normal stress in the slipping regions or a smaller value for the parameter describing rate dependence of friction a b than is indicated by laboratory experiments our best afterslip model suggests that the coulomb stress at the duzce hypocenter increased by 0 14 mpa 1 4 bars during the izmit earthquake assuming right lateral slip on a surface dipping 50 to the north and by another 0 1 mpa during the 87 days between the izmit and duzce earthquakes in the marmara sea region within about 160 km of the izmit earthquake rupture this model indicates that the coulomb stresses increased by 15 25 of the coseismic amount during the first 300 days after the earthquake three hundred days after the earthquake postseismic contributions to coulomb stressing rate on the maramara region faults had fallen to values equal to or less than the inferred secular stress accumulation rate our estimates of postseismic coulomb stress are highly model dependent in the marmara region the linear viscous shear zone and viscoelastic lower crust models predict greater postseismic coulomb stresses than the frictional afterslip model near field stress and fault zone rheology estimates are sensitive to the earth9s elastic structure when a layered elastic structure is incorporated in our model it yields a coulomb stress of 0 24 mpa at the duzce hypocenter significantly more than the 0 14 mpa estimated from the uniform elastic model because of the higher near field coseismic stresses the layered elastic model requires a higher value of velocity strengthening parameter a b a b times effective normal stress r to produce comparable postseismic slip a b is estimated at 0 4 and 0 2 mpa respectively for the layered and uniform elastic models these results highlight the importance of understanding the earth9s elastic structure and the mechanism for postseismic deformation if we wish to accurately model coseismic and postseismic crustal stresses

variation of seismic coupling with slab detachment and upper plate structure along the western hellenic subduction zone abstract the western hellenic subduction zone is characterized by a trenchward velocity of the upper plate in the ionian islands segment complete seismic coupling is achieved as is predicted by standard plate tectonic models in which there is no slab pull force because the slab has broken off the moderate local seismic moment rate relates to a shallow downdip limit for the seismogenic interface this characteristic may be attributed to the ductility of the lower crust of the upper plate which allows a decollement between the upper crust of the overriding plate and the subducting plate farther south a deeper downdip limit of the seismogenic interface is indicated by thrust faulting earthquakes which persist much deeper in western crete a correspondingly larger downdip width of this seismogenic zone is consistent with the suggested larger maximum magnitude of earthquakes here however since the seismic moment release rate seems to be moderate in the peloponnese and western crete like in in the ionian islands this seismically active interface cannot maintain complete seismic coupling across its larger downdip width a cause may be the lateral addition of overweight to the part of the slab still attached in crete by the free fall of its part that has broken off from the surface further north this increased slab pull reduces the compressive normal stress across the seismogenic interface and thus causes partial seismic coupling in its shallower part however the width of this part may provide an additional area contributing to slip in large earthquakes which may nucleate deeper on stick slip parts of the interface hints at anomalies in structure and seismicity which need to be resolved may relate to the present location of the edge of the tear in the slab

2d reflection seismic investigations at the kevitsa ni cu pge deposit northern finland in 2007 a 2d reflection seismic survey was conducted at the kevitsa ni cu pge platinum group elements deposit in northern finland the aims of the survey were to delineate the overall extent of

kinematics of active left lateral faulting in se turkey from offset pleistocene river gorges improved constraint on the rate and history of relative motion between the turkish and arabian plates in the arabian platform of se turkey abundant evidence exists of fluvial incision by c 110 10 m since the late early pleistocene starting in or around marine oxygen isotope stage 22 at 870 ka this incision which has accompanied regional surface uplift as the isostatic response to regional erosion has progressively locked rivers into their gorges in landscape that formerly had much lower relief we use this effect to estimate 4 44 0 06 km of left lateral slip on this time scale on the golbasi turkoglu fault a segment of the east anatolian fault zone from offset river gorges giving a slip rate of 5 10 0 07 mm a 1 piercing points indicate that this fault has slipped a total of 19 km making its age 3 73 0 05 ma a total of 33 km of relative motion between the turkish and arabian plates is documented on this time scale in the vicinity of golbasi at an overall time averaged rate of 8 85 0 12 mm a 1 the estimated euler vector for relative motion between these plates being 0 89 0 01 ma 1 about 33 4 n 42 3 e this method can be readily applied to determine slip rates time averaged since the late early pleistocene on other strike slip fault zones worldwide

seismic depth imaging of iron oxide deposits and their host rocks in the ludvika mining area of central sweden abstract the development of cost effective and environmentally acceptable geophysical methods for the exploration of mineral resources is a challenging task seismic methods have the potential to delineate the mineral deposits at greater depths with sufficiently high resolution in hardrock environments which typically host the majority of metallic mineral deposits seismic depth imaging workflows are challenged by steeply dipping structures strong heterogeneity and the related wavefield scattering in the overburden as well as the often limited signal to noise ratio of the acquired data in this study we have developed a workflow for imaging a major iron oxide deposit at its accurate position in depth domain while simultaneously characterizing the near surface glacial overburden including surrounding structures like crossing faults at high resolution our workflow has successfully been showcased on a 2d surface seismic legacy data set from the ludvika mining area in central sweden acquired in 2016 we applied focusing prestack depth imaging techniques to obtain a clear and well resolved image of the mineralization down to over 1000 m depth in order to account for the shallow low velocity layer within the depth imaging algorithm we carefully derived a migration velocity model through an integrative approach this comprised the incorporation of the tomographic near surface model the extension of the velocities down to the main reflectors based on borehole information and conventional semblance analysis in the final step the evaluation and update of the velocities by investigation of common image gathers for the main target reflectors were used although for our data set the reflections from the mineralization show a strong coherency and continuity in the seismic section reflective structures in a hardrock environment are typically less continuous in order to image the internal structure of the mineralization and decipher the surrounding structures we applied the concept of reflection image spectroscopy to the data which allows the imaging of wavelength specific characteristics within the reflective body as a result conjugate crossing faults around the mineralization can directly be imaged in a low frequency band while the internal structure was obtained within the high frequency bands

comment on late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates by m allen j jackson and r walker

eustatic and tectonic controls upon quaternary coastal sedimentation in the corinth basin greece the late quaternary sedimentology and palaeogeography of the corinth isthmus in central greece is re interpreted a series of beach to shoreface sub sequences are seen each characteristically having an overall fining up character these occur within a coastal facies belt which has prograded to the west computer modelling illustrates the interaction of tectonic displacements and eustatic sea level variation as controls of facies patterns late pleistocene holocene facies geometries are predicted on the basis of published sea level data over that time interval on coastlines undergoing tectonic uplift such as the isthmus of corinth depositional patterns may be characterized by transgressive wedges these sub sequences merge basinwards below sea level minima each transgression relates to a major eustatic sea level peak such first order models are modified by variations in the rate of tectonic deformation the second control on relative sea level position modelled facies patterns are tested on the basis of new 230 th 234 u dates obtained from sclerac tinian corals of the corinth canal area dated sub sequence sediments correspond in age to late pleistocene eustatic highs and observed facies patterns correlate with the major late pleistocene holocene eustatic transgressions of c 100 ka periodicity episodes of intrabasinal normal faulting are isolated from a structural history otherwise dominated by uplift across the isthmus quantification of post depositional vertical tectonic displacements is achieved constraining the eustatic base level at the time of deposition of a dated horizon by reference to the global late quaternary sea level curve the original depositional level is then subtracted from the present outcrop level using available 230 th 234 u dates to establish syn depositional base levels minimum uplift rates of the order of 0 3 m ka 1 are calculated across the area averaged through the late pleistocene and holocene

dating quaternary volcanism and incision by the river tigris at diyarbakir southeast turkey new high precision ar ar dating of basalt underlying the city of diyarbakir southeast turkey constrains the quaternary incision history of the river tigris strengthening the pre existing chronology based on magnetostratigraphy and k ar dates the basalt which overlies tigris terrace gravel 70 m above the river is part of the karacadag shield volcano complex centred ca 60 km to the southwest the reverse magnetised diyarbakir basalt one of relatively few flow units to reach the tigris valley axis has been dated to 1196 19 ka 2 two lower terraces have been recognised in the diyarbakir area 46 and 32 m above the present river with at least one other further downstream from this evidence the rate of middle late pleistocene incision by the tigris can be estimated it probably reached ca 0 07 mm a 1 reflecting the characteristic global increase in uplift rates observed at that time copyright 2007 john wiley sons ltd

investigation of coupling between surface processes and induced flow in the lower continental crust as a cause of intraplate seismicity many studies have highlighted the role of coupling between surface processes and flow in the lower continental crust in deforming the crust and creating topographic relief over quaternary timescales on the basis of the rheological knowledge gained it is suggested that intraplate seismicity can also be caused by coupling between surface processes and flow in the lower continental crust this view is shown to be a natural consequence of the modern idea that isostatic equilibrium is maintained by flow in the weak lower crust in response to erosion and sedimentation it is supported by a general correlation between the vigour of surface processes and rates of intraplate seismicity and by instances of seasonal seismicity that correlates with seasonal climate human interference in the environment can affect surface loading for instance deforestation for agriculture or urban development can cause increased erosion rates global warming is expected to cause increased storminess and thus increased erosion rates and or global sea level rise the possibility of increased rates of seismicity resulting from these processes should thus be considered in future hazard assessment copyright 2006 john wiley sons ltd

improved modelling of the quaternary evolution of the gulf of corinth incorporating erosion and sedimentation coupled by lower crustal flow abstract numerical modelling incorporating coupling between surface processes and induced flow in the lower continental crust is used to address the quaternary evolution of the gulf of corinth region in central greece the post early pleistocene marine depocentre beneath this gulf overlies the northern margin of an older early pleistocene and earlier lacustrine basin the proto gulf of corinth basin or pgcb in the late early pleistocene relief in this region was minimal but subsequently dramatic relief has developed involving the creation of 900 m of bathymetry within the gulf and the uplift by many hundreds of metres of the part of the pgcb south of the modern gulf which forms the gulf s main sediment supply it is assumed that as a result of climate change around 0 9 ma erosion of this sediment source region and re deposition of this material within the gulf began both processes occurring at spatial average rates of 0 2 mm a 1 modelling of the resulting isostatic response indicates that the local effective viscosity of the lower crust is 4 10 19 pa s indicating a moho temperature of 560 c it predicts that the 10 mm a 1 of extension across this 70 km wide model region at an extensional strain rate of 0 15 ma 1 is partitioned with 3 mm a 1 across the sediment source 2 mm a 1 across the depocentre and 5 mm a 1 across the hinge zone in between the latter value being an estimate of the extension rate on normal faults forming the major topographic escarpment at the southern margin of the gulf this modelling confirms the view suggested previously that coupling between this depocentre and sediment source by lower crustal flow can explain the dramatic development in local relief since the late early pleistocene the effective viscosity of the lower crust in this region is not particularly low the strong coupling interpreted between the sediment source and depocentre results instead from their close proximity in detail the effective viscosity of the lower crust is expected to decrease northward across this model region due to the northward increase in exposure of the base of the continental lithosphere to the asthenosphere in the south the two are separated by the subducting hellenic slab the isostatic consequences of such a lateral variation in viscosity provide a natural explanation for why since 0 9 ma the modern gulf has developed asymmetrically over the northern part of the pgcb leaving the rest of the pgcb to act as its sediment source

ar ar dating of late cenozoic basaltic volcanism in northern syria implications for the history of incision by the river euphrates and uplift of the northern arabian platform 1 ar ar dating of basalt flows capping terrace deposits of the river euphrates in northern syria has provided a new quantitative chronology for the late cenozoic evolution of this important river system and for the associated history of surface uplift of the northern arabian platform through which it flows a region of relatively strong crust that has experienced only slow deformation notably fluvial deposits 65 m above the euphrates are overlain by basalt dated to 2717 20 ka those 45 m above the river are overlain by basalt dated to 2116 39 ka and those 8 9 m above the river are overlain by basalt dated to 402 11 ka these new dates require the previous dating scheme based on paleolithic archaeology to be revised the euphrates terrace deposits and the associated incised valley are much older than was previously thought rates of incision by the euphrates providing a proxy for regional surface uplift that is inferred to be the isostatic response to regional erosion have varied significantly over the past 3 ma with indications that between 1 2 and 0 9 ma there was regional subsidence which gave rise to fluvial aggradation this unusual pattern involving reversals in the sense of vertical crustal motions is interpreted to be a consequence of a relatively cold and thin mobile lower crustal layer no more than 5 km thick evidently due to the presence of a much thicker underlying layer of mafic underplating at the base of the crust this study thus indicates previously unsuspected complexity in the isostatic response to regional erosion in an area of high crustal stability

conditions for flow in the continental crust 1 earthquake focal depth distributions and effective elastic thickness variations on the continents suggest that in old cold regions such as shields the lower continental crust can be stronger than the upper mantle and imply that the upper mantle can flow even when the lower crust does not however in other places substantial flow in the lower crust does occur particularly near extensional metamorphic core complexes we suggest that the lower crust only flows when its viscosity is significantly reduced either by heating from igneous intrusions or by the addition of water in both cases the important characteristics of the flow are a consequence of the limited time over which the viscosity reduction occurs the timescale is controlled either by conductive cooling of intrusions or by the separation of melt from its matrix which removes the water

3d seismic imaging of volcanogenic massive sulfide deposits in the flin flon mining camp canada part 2 forward modeling abstractwe applied seismic modeling for a detailed 3d geologic model of the flin flon mining camp canada to address some imaging and interpretation issues related to a 17 km2 3d survey acquired in the camp and described in a complementary paper part 1 a 3d geologic volumetric model of the camp was created based on a compilation of geologic data constraints from drillholes surface geologic mapping interpretation of 2d seismic profiles and 3d surface and grid geostatistical modeling techniques the 3d modeling methodology was based on a hierarchical approach to account for the heterogeneous spatial distribution of geologic constraints elastic parameters were assigned within the model based on core sample measurements and correlation with the different lithologies the phase screen algorithm used for seismic modeling was validated against analytic and finite difference solutions to ensure that it provided accurate amplitude variation with offset behavior for dipping strata synthetic data were gener

seismic methods for deep mineral exploration mature technologies adapted to new targets nonseismic methods such as electromagnetic induced polarization and potential field surveying techniques have been the geophysical backbone of mineral exploration for decades these methods exploit anomalous physical properties of ore deposits e g enhanced conductivity chargeability or magnetization to locate potential targets for drilling although well suited to many shallow 500 m exploration problems the underlying physical principles of these methods impose inescapable limitations on their sensitivity and resolving power at depth recent declines in base metal reserves caused by the depletion of known shallow deposits and declining rates of discovery for new deposits underscore the need for geophysical exploration methods that can locate economically viable deposits at depths of up to several km seismic methods offer one possible solution the need to develop efficient and robust seismic imaging techniques for mineral exploration has long been recognized in the 1980s two key case histories established the potential of seismics as a mapping tool in the hardrock environment green and mair 1983 presented seismic images of complex fracture systems at a radioactive waste disposal site in the canadian shield subsequently pretorius et al 1989 demonstrated the usefulness of an integrated seismic and petrophysical approach to image key geologic structures for mineral exploration in witwatersrand basin south africa these initial studies served as catalysts for a number of largely independent research efforts over the following decade in north america southern africa scandinavia and australia aimed at developing useful and cost effective seismic technology for deep mineral exploration and mine planning a number of fundamental aspects of seismic exploration for minerals including the acoustic properties of ores and the scattering characteristics of orebodies were poorly known until recently moreover significant advances have been made in seismic imaging technology for mineral exploration from downhole seismic techniques to large scale 3d surveys over known deposits this article reviews some advances in applying seismic

dependence of active normal fault dips on lower crustal flow regimes two key questions are raised by the presence in the basin and range province of subhorizontal normal faults which were active in and around the miocene first how did they develop when their existence seems to be precluded by elementary rock mechanics arguments second if they did slip in the recent geological past why do normal faults now active in the brittle upper crust have steeper dips both in the western usa and elsewhere one may now answer both questions by considering the stress field in regions where the isostatic response during extension involves horizontal flow in the plastic lower crust this stress tensor will have inclined principal axes making it possible for normal faults to form with either very steep or subhorizontal dips depending on the sense of flow this can be controlled by environmental conditions which influence rates of hanging wall sedimentation and footwall erosion and thus determine lateral variations in lithostatic pressure in the lower crust regional scale lateral variations in the geothermal gradient caused by subduction can also influence lower crustal flow regimes in adjacent zones of continental extension enabling extension to occur on low angle normal faults dipping away from the active continental margin

interferometric ground roll removal attenuation of scattered surface waves in single sensor data land seismic data are contaminated by surface waves or ground roll these surface waves are a form of source generated noise and can be strongly scattered by near surface heterogeneities the resulting scattered ground roll can be particularly difficult to separate from the desired reflection data especially when this scattered ground roll propagates in the crossline direction we have used seismic interferometry to estimate scattered surface waves recorded during an exploration seismic survey between pairs of receiver locations where sources and receivers coincide these interreceiver surface wave estimates were adaptively subtracted from the data this predictive subtraction process can successfully attenuate scattered surface waves while preserving the valuable reflected arrivals forming a new method of scattered ground roll attenuation we refer to this as interferometric ground roll removal

using supervirtual first arrivals in controlled source hardrock seismic imaging well worth the effort varied applications of seismic interferometry have arisen in the last decade however the potential of the method to improve reflection seismic processing in hardrock environments has not explicitly been regarded therefore in this paper we investigate the potential of retrieving the first arrivals originally hindered by high noise level in the exploitation of controlled source data acquired over the iron oxide apatite rich deposit at grangesberg sweden and its mining induced structures the supervirtual first arrivals retrieved using interferometry methodologies allowed first breaks to be picked more extensively than in the original data revised static corrections significantly improved the linearity of the first arrivals and continuity of reflections in the source gathers especially reflections considerably enhanced in the source gathers stacked constructively in the final section comparison with geological data supported by traveltime forward modelling indicates that these reflections represent the unmined part of the deposit other reflections at shallower depth are interpreted as anthropogenic faults possibly located at lithological contacts tomographic inversion was also run using the augmented traveltime data the greater resolution and penetration of this new tomographic image allowed better bridging with the results of the reflection seismic section velocity anomalies depict the presence of mining induced structures and a potential brewery fault which is believed to put at risks an urban area even though the potential of first arrival retrieval seems to be case dependent this study illustrates that interferometry may substantially improve the accuracy of static corrections and subsequent stack for hardrock imaging as well as in the penetration and resolution of traveltime tomograms

late cenozoic surface uplift basaltic volcanism and incision by the river tigris around diyarbakir se turkey we document the staircase of terraces of the river tigris in the diyarbakir area of se turkey in the northern arabian platform and improve control on the ages of these terrace deposits by dating of overlying basalt flows using the unspiked k ar technique these fluvial terraces are formed of polymict gravel including clasts derived from the anatolian metamorphic terrane farther north as well as of local basalt at least 9 tigris terraces have been recognised so far the highest of which 200 m above present river level marks the local transition from stacked deposition to fluvial incision the timing of which is bounded between the mid late miocene and the middle pliocene our k ar dating indicates a hiatus in fluvial incision in the late early pleistocene as basalts dated to 1 22 0 02 and 1 07 0 03 ma overlie tigris gravels at very similar levels 60 70 m above the present river the lower terraces record the subsequent entrenchment of the modern tigris valley following an increase in incision rates in the early middle pleistocene evident from the disposition of younger basalt dated to 0 43 0 02 ma capping fluvial gravel only 21 22 m above the present river level numerical modelling can account for the observed uplift history as the response to coupling between surface processes and induced flow in the lower crust with the mobile lower crust thin 5 7 km thick consistent with the known presence of a thick layer of mafic underplating at the base of the crust beneath the arabian platform

isostatic compensation of quaternary vertical crustal motions coupling between uplift of britain and subsidence beneath the north sea new data from offshore and onshore regions confirm the view that the quaternary uplift of britain and subsidence beneath the north sea are coupled mediated by lower crustal flow induced by the lateral pressure gradient caused by climate driven surface processes most measured onshore uplift rates in both upland and lowland localities are only applicable since the mid pleistocene revolution beforehand generally lower rates prevailed earlier oligocene pliocene phases of uplift and subsidence had typically even lower rates furthermore the western margin of the north sea depocentre was 200 km farther from the modern coastline of north east england in the earliest cenozoic complex isostatic adjustments occurred in response to the magmatism associated with the iceland mantle plume the contemporaneous land surface relative to the present day rock column in northern england was typically 1500 m od however this activity died out during the palaeogene the main effect of these events on the modern isostatic configuration was via the emplacement of thick mafic underplating which now constricts the mobile lower crustal layer explaining the late cenozoic ultra stability of ireland the evidence enables interpretations of the present day topography of britain as static caused by the iceland mantle plume or actively developing in response to plate motions or plate boundary forces to be excluded

crustal and upper mantle structure beneath the corinth rift greece from a teleseismic tomography study we report here the results of a tomographic lithospheric study in the area of the corinth and evvia rifts greece designed to constrain the mechanism of continental extension sixty seismological stations were deployed in the area for a period of 6 months and 177 teleseismic events were recorded by more than five stations and gave more than 2000 travel time residuals p and pkp phases which were inverted to image the velocity structure down to 200 km depth we use both a linear and a nonlinear method to invert the data set the main result is a long wavelength positive velocity anomaly located in the upper mantle which is interpreted as the subducted african lithosphere the subducted lithosphere is well defined from 7o km depth down to 200 km from synthetic tests as well as from the amplitude of the anomaly more than 7 we conclude that the subduction continues below 200 km in addition a second positive velocity anomaly of about 4 from the surface down to 40 km depth located north of the gulf of corinth has been found this is interpreted as the result of a crustal thinning of several kilometers 5 km shifted to the north from the gulf of corinth and trending obliquily nw se we suggest that this crustal thinning is mainly related to the miocene widespread extension in the aegean and that the quaternary corinth rift initiated where the crust was already thinned the different styles of deformation of the eastern and western part of the rift are consistent with this interpretation no clear velocity anomaly can be related to the evvia rift

moho topography beneath the corinth rift area greece from inversion of gravity data summary our aim is to understand better the rifting process by imaging the moho depth variation beneath corinth and evvia we present here the results of a gravity inversion analysis in the region of the corinth and evvia rift system and compare them to those obtained independently from teleseismic tomography and receiver function analyses the results of these different studies appear to be consistent and show 1 a 10 km crustal thickening in the western part of the area beneath the hellenides mountains 2 nw se trending periodic crustal thinning and 3 a maximum crustal thinning north of the gulf of corinth this 4 km thinning is unlikely to be the result of the rifting alone which seems to have been reactivated since only 1 ma we propose here a geodynamical scenario in two major steps to explain the evolution of corinth area aegean miocene extension involving boudinage resulted in periodic crustal thinning consistent with observations these lithospheric instabilities could have favoured rupture initiation in particular areas especially near the city of corinth then the reactivation of the corinth rift extension 1 myr ago led to westward rift propagation the offset observed between the maximum crustal thinning and the gulf of corinth could be accommodated by a lowangle normal fault at about 10 15 km depth the corinth rift is thus asymmetrical and was initiated in places of crustal weakness due to miocene lithospheric instabilities

localization of quaternary slip rates in an active rift in 105 years an example from central greece constrained by 234u 230th coral dates from uplifted paleoshorelines mapping dating and modeling of paleoshorelines uplifted in the footwall of the 1981 gulf of corinth earthquake fault greece ms 6 9 6 7 are used to assess its slip rate history relative to other normal faults in the area and study strain localization the 234u 230th coral ages from cladocora caespitosa date uplifted shoreface sediments and paleoshorelines from glacioeustatic sea level highstands at 76 possibly 100 125 175 200 216 240 and 340 ka uplifted quaternary and holocene paleoshorelines decrease in elevation toward the western tip of the fault exhibiting larger tilt angles with age showing that uplift is due to progressive fault slip since 125 ka uplift rates varied from 0 25 to 0 52 mm yr over a distance of 5 km away from the fault tip tilting was also occurring prior to 125 ka but uplift rates were lower because the 125 ka paleoshoreline is at 77 of the elevation of the 240 ka paleoshoreline despite being nearly half its age comparison of paleoshoreline elevations and sedimentology with the quaternary sea level curve shows that slip rates increased by a factor of 3 2 0 2 at 175 75 ka synchronous with cessation of activity on a neighboring normal fault at 382 112 ka we suggest that the rapid localization of up to 10 15 mm yr of extension into the narrow gulf 30 km wide resulted from synchronous fault activity on neighboring faults followed by localization rather than sequential faulting with consequences for the mechanism controlling localization of extension

cross profile seismic data acquisition imaging and modeling of iron oxide deposits a case study from blotberget south central sweden cross profile seismic data acquisition imaging and modeling of iron oxide deposits a case study from blotberget south central sweden

late cenozoic uplift of the amanos mountains and incision of the middle ceyhan river gorge southern turkey ar ar dating of the duzici basalt using the ar ar technique we have obtained the first numerical dates for the pleistocene volcanism along the valley of the river ceyhan in the duzici area of southern turkey in the western foothills of the amanos mountains our six dates indicate a single abrupt episode of volcanism at 270 ka we have identified a staircase of 7 fluvial terraces at altitudes of up to 230 m above the present level of the ceyhan using the disposition of the basalt as an age constraint we assign these terraces to cold climate stages between marine oxygen isotope stages 16 and 2 indicating rates of fluvial incision equated to surface uplift that increase upstream through the western foothills of this mountain range at between 0 25 and 0 4 mm a 1 extrapolation of these uplift rates into the axis of the range suggests that the entire 2300 m of present day relief has developed since the mid pliocene a view that we confirm using numerical modelling since 3 7 ma the amanos mountains have formed a transpressive stepover along the northern part of the dead sea fault zone where crustal shortening is required by the geometry using a physics based technique we have modelled the overall isostatic response to the combination of processes occurring including crustal thickening caused by the shortening erosion caused by orographic precipitation and the resulting outward flow of mobile lower crustal material in order to predict the resulting history of surface uplift this modelling suggests that the effective viscosity of the lower crust in this region is in the range 1 2 1019 pa s consistent with a moho temperature of 590 10 c the latter value being in agreement with heat flow data this modelling shows that the nature of the active crustal deformation is now understood to first order at least in this key locality within the boundary zone between the african and arabian plates the structure and geomorphology of which have been fundamentally misunderstood in the past

cenozoic cooling histories in the menderes massif western turkey may be caused by erosion and flat subduction not low angle normal faulting abstract since the early 1990s a prolific literature has developed on the interpretation within western turkey of apparent mid to late cenozoic low angle normal faults extension on these structures has been thought responsible for the exhumation of this region s principal metamorphic massif the menderes massif which has thus been interpreted as a metamorphic core complex nonetheless no convincing supporting structural evidence has emerged some reported instances of low angle normal faulting affecting the menderes massif can be shown from field relationships to have formed as steep normal faults and to have since become back tilted others seem to be misinterpretations of structures with no demonstrable relationship to extension at all the main evidence for low angle normal faulting in this region has instead emerged through thermochronology which indicates highly non uniform cooling histories that have seemed to lack any other explanation however this evidence can alternatively be explained by a combination of the cooling effects caused by flat subduction and by erosion there is thus no evidence for cenozoic low angle normal faulting affecting the menderes massif extension started at 11 ma in parts of western turkey but most of this region s late cenozoic extension on normal faults with steep initial dips has occurred since 7 ma synchronous with slip on the north anatolian fault zone

pliocene and quaternary regional uplift in western turkey the gediz river terrace staircase and the volcanism at kula abstract along the upper reaches of the gediz river in western turkey in the eastern part of the aegean extensional province the land surface has uplifted by 400 m since the middle pliocene this uplift is revealed by progressive gorge incision and its rate can be established because river terraces are capped by basalt flows that have been k ar and ar ar dated at present the local uplift rate is 0 2 mm a 1 uplift at this rate began around the start of the middle pleistocene following a span of time when the uplift was much slower this was itself preceded by an earlier uplift phase apparently in the late late pliocene and early early pleistocene when the uplift rate was comparable to the present the resulting regional uplift history resembles what is observed in other regions and is analogously interpreted as the isostatic response to changing rates of surface processes linked to global environmental change we suggest that this present phase of surface uplift amounting so far to 150 m is being caused by the nonsteady state thermal and isostatic response of the crust to erosion following an increase in erosion rates in the late early pleistocene most likely as a result of the first large northern hemisphere glaciation during oxygen isotope stage 22 at 870 ka we suggest that the earlier uplift phase responsible for the initial 250 m of uplift resulted from a similar increase in erosion rates caused by the deterioration in local climate at 3 1 ma this uplift thus has no direct relationship to the crustal extension occurring in western turkey the rate and sense of which are thought not to have changed significantly on this time scale our results thus suggest that the present often deeply incised landscape of western turkey has largely developed from the middle pleistocene onwards for reasons not directly related to the active normal faulting that is also occurring the local isostatic consequences of this active faulting are instead superimposed onto this background of regional surface uplift modelling of this surface uplift indicates that the effective viscosity of the lower continental crust beneath this part of turkey is of the order of 1019 pa s similar to a recent estimate for beneath central greece the lower uplift rates observed in western turkey compared with central greece result from the longer typical distances of fluvial sediment transport which cause weaker coupling by lower crustal flow between offshore depocentres and eroding onshore regions that provide the sediment source

quaternary deformation of the isthmus and gulf of corinthos greece interdisciplinary data suggest that the quaternary late holocene and present day deformation patterns of the isthmus of corinthos greece are very similar and can be compared to a platelike body under torsion this hypothesis is consistent with the vertical differential motions observed in the adjacent corinthiakos gulf a possible explanation is that the back arc compressional zone is much wider than formerly believed and extends to an area of normal faulting parallel to the direction of the compression this stress field produces a central bulging in the southern coast and a depression in the northern coast of the corinthiakos gulf the easternmost ends of this depression and bulging are the southern and northern parts of the isthmus tilted to the east and to the west respectively

retrieving surface waves from ambient seismic noise using seismic interferometry by multidimensional deconvolution retrieving virtual source surface waves from ambient seismic noise by cross correlation assumes among others that the noise field is equipartitioned and the medium is lossless violation of these assumptions reduces the accuracy of the retrieved waves a point spread function computed from the same ambient noise quantifies the associated virtual source s spatial and temporal smearing multidimensional deconvolution mdd of the retrieved surface waves by this function has been shown to improve the virtual source s focusing and the accuracy of the retrieved waves using synthetic data we tested mdd on data recorded during the batholiths experiment a passive deployment of broadband seismic sensors in british columbia canada the array consisted of two approximately linear station lines using 4 months of recordings we retrieved fundamental mode rayleigh waves 0 05 0 27 hz we only used noise time windows dominated by waves that traverse the northern line before reaching the southern 2 5 of all data compared to the conventional cross correlation result based on this subset the mdd waveforms are better localized and have significantly higher signal to noise ratio furthermore mdd corrects the phase and the spatial deconvolution fills in a spectral f k domain gap between the single frequency and double frequency microseism bands frequency whitening of the noise also fills the gap in the cross correlation result but the signal to noise ratio of the mdd result remains higher comparison of the extracted phase velocities shows some differences between the methods also when all data are included in the conventional cross correlation

initial crustal thickness geometry controls on the extension in a back arc domain case of the gulf of corinth 1 since 60 myr peloponnesus and continental greece have been affected by the hellenidean compressional and the aegean extensional phases this complex evolution resulted in development of a strongly inhomogeneous crust in the gulf of corinth region to study this area we use a large strain thermomechanical numerical code paravoz previously used for a number of similar problems such as rift evolution yet instead of varying boundary and initial conditions applied to a plane layered model we use available geophysical constraints on the actual deep structure of the lithosphere to test its different possible initial structures by varying the position of the initial crustal heterogeneity versus the position of the lithospheric slab we are able to explain the origin of the internal structures and the kinematics of the gulf of corinth the results suggest that the development of shear zones in the lower crust is favored by the gravitational collapse of the thicker part of the crust whereas the geometry and the kinematics of these shear zones are controlled by the position of the edge of the slab asymmetry is seen in cases when a horizontal shift exists between the edge of the slab and the thicker part of the crust our model explains the differences between the northern shore and the southern shore as well as the east west variations observed in the gulf of corinth

fluid involvement in the active helike normal fault gulf of corinth greece abstract rock fabric and mineralogical composition from the fault core and the unaffected protolith have been used to define the role of the segmented helike fault to fluid flow sixty samples were investigated by xrd sem observation and sem eds microanalyses detrital smectite calcite and quartz represent the mineral assemblage at the crest of the footwall block in foniskaria sampling site in this site smectite is enriched at the rims of the fault core all other sampling sites located at the base of the fault scarp are characterized by detrital and newly formed minerals detrital minerals include plagioclase quartz calcite and illite in nikolaiika sampling site and smectite illite kaolinite quartz calcite in selinous sampling site in the latter sampling site erionite and cerussite are newly formed minerals with erionite considered as the hydrothermal alteration product of fluids at 80 100 c at the eastern fault segment illite quartz and calcite t13 site corresponds to detrital minerals mineralogy in the fault core reflects its high permeability to down flowing meteoric water and weak hydrothermal alteration the rock fabric suggests mineral alignment parallel to the fault plane mineralogy indicates that the aigion helike and pyrgaki faults in the gulf of corinth host hydrothermal activity at shallow levels

adaptive subtraction of multiples using the l1 norm a strategy for multiple removal consists of estimating a model of the multiples and then adaptively subtracting this model from the data by estimating shaping filters a possible and efficient way of computing these filters is by minimizing the difference or misfit between the input data and the filtered multiples in a least squares sense therefore the signal is assumed to have minimum energy and to be orthogonal to the noise some problems arise when these conditions are not met for instance for strong primaries with weak multiples we might fit the multiple model to the signal primaries and not to the noise multiples consequently when the signal does not exhibit minimum energy we propose using the l 1 norm as opposed to the l 2 norm for the filter estimation step this choice comes from the well known fact that the l 1 norm is robust to large amplitude differences when measuring data misfit the l 1 norm is approximated by a hybrid l 1 l 2 norm minimized with an iteratively reweighted least squares irls method the hybrid norm is obtained by applying a simple weight to the data residual this technique is an excellent approximation to the l 1 norm we illustrate our method with synthetic and field data where internal multiples are attenuated we show that the l 1 norm leads to much improved attenuation of the multiples when the minimum energy assumption is violated in particular the multiple model is fitted to the multiples in the data only while preserving the primaries

downhole physical property logging for iron oxide exploration rock quality and mining an example from central sweden abstract several physical properties obtained from geophysical logging and laboratory measurements were analyzed in order to characterize iron oxide mineralization and host rocks in the blotberget mining area of central sweden seven boreholes intersecting the mineralization between 300 and 600 m depth in a volcano sedimentary setting were downhole logged for this purpose the downhole logging included full waveform triple sonic natural gamma magnetic susceptibility formation resistivity fluid temperature and conductivity while laboratory measurements consisted of density rock quality designation and magnetite content measurements full waveform sonic data were used for rock quality assessments of the mineralized zones and their host rocks and proved their potential to be used for mine planning purposes the ore bearing rocks are primarily distinguished by increased density and dynamic elastic moduli estimated from the full waveform sonic logging although seismic velocities do not follow a linear increase with the density for the mineralized rocks as expected for igneous rocks it is observed that a strong seismic signal from the mineralization can be expected primarily due to their high density in addition the full waveform sonic data could be used as a proxy for fracture delineations and in situ rock quality assessment for example zones of washed up amplitudes in these data correlate well with zones of poor quality rocks identified by core logging based on the full waveform sonic data seismic attenuation and its reciprocal the seismic quality factor were calculated a decrease in the seismic quality factor was observed at zones with low rock quality designation but also correlated with the mineralized zones suggesting several fracture zones in the mineralization and that the ore bearing rocks might be less competent than the surrounding host rocks eventual rock support and reinforcement might be required for future mining operations full waveform sonic data have the potential to improve rock quality assessments for mine planning and exploration purposes

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

river terrace development in the ne mediterranean region syria and turkey patterns in relation to crustal type it is widely recognized that the optimal development of river terraces globally has been in the temperate latitudes with nw and central europe being areas of particular importance for the preservation of such archives of quaternary environmental change there is also a growing consensus that the principal drivers of terrace formation have been climatic fluctuation against a background of progressive but variable uplift nonetheless river terraces are widely preserved in the mediterranean region where they have often been attributed to the effects of neotectonic activity with a continuing debate about the relative significance of fluctuating temperature glacials interglacials and precipitation pluvials interpluvials research in syria and southern central turkey specifically in the valleys of the tigris and ceyhan in turkey the kebir in syria and the trans border rivers orontes and euphrates has underlined the importance of uplift rates in dictating the preservation pattern of fluvial archives and has revealed different patterns that can be related to crustal type the ne mediterranean coastal region has experienced unusually rapid uplift in the late quaternary the relation between the kebir terraces and the staircase of interglacial raised beaches preserved along the mediterranean coastline of nw syria reinforces previous conclusions that the emplacement of the fluvial terrace deposits in the mediterranean has occurred during colder climatic episodes

an obliquity controlled early pleistocene river terrace record from western turkey investigation of the pleistocene sequence of the gediz river western turkey has revealed a record of early pleistocene river terraces eleven terraces spanning the interval from 1 67 to 1 245 million years ago mis 59 37 are preserved beneath basaltic lava flows the high number of terraces over this short time period reflects high frequency sedimentation incision cycles preserved due to the fortuitous combination of relatively high uplift rates 0 16 mm yr 1 and progressive southwards valley migration comparison of this record with odp967 from the eastern mediterranean basin suggests a link between the production of terraces and obliquity driven 41 000 year climate cycles in the early pleistocene

quaternary elevation change of the gulf of corinth in central greece dramatic elevation changes have occurred since early pleistocene time in and around the gulf of corinth sedimentary basin in central greece which is actively extending at a maximum rate of ca 2 mm a 1 shoreline deposits younger than 1 million years are found at up to ca 1200 m elevation south of the gulf with sediment from an older plio pleistocene basin above 1750 m the gulf floor in the hanging wall of normal faults along its southern coast has subsided up to ca 1650 m on the same timescale however other hanging wall localities such as the corinth isthmus east of the gulf have uplifted instead during the past million years the gulf has alternated between marine and lacustrine environments in response to glacially induced sea level variations this study establishes its chronology of marine and lacustrine terraces for the past half million years allowing lateral variations in uplift to be investigated to explain the observed elevation changes it is suggested that ca 0 9 million years ago the previously lacustrine gulf became flooded by ca 80 m during an interglacial marine highstand the resulting ca 0 8 mpa increase in lithostatic pressure at the base of the brittle upper crust caused southward lower crustal flow to beneath the older plio pleistocene basin isostatic adjustment uplifted this basin creating unstable topography that enabled rapid erosion this lower crustal flow which since been maintained by the sediment load in the gulf that results from this erosion also causes the hanging wall uplift of the corinth isthmus and other anomalous localities the gulf of corinth is thus an important case study locality for revealing the existence of lower crustal flow during continental extension

late cenozoic uplift of southern italy deduced from fluvial and marine sediments coupling between surface processes and lower crustal flow abstract we investigate the rates and magnitudes of late pliocene pleistocene uplift at key localities in the southern italian regions of basilicata and calabria using fluvial and marine terraces these rates show strong lateral variations reaching maxima of 1 mm a 1 or more in the southern apennines which have uplifted by many hundreds of metres since the late early pleistocene and by well over 1 km since the middle pliocene integrated study has been facilitated by the realisation that altitudes of river terraces in this region require substantial correction for downstream channel lengthening given the rapid coastal progradation that is occurring before they can be compared with altitudes of marine terraces these high rates of uplift and the corresponding rates of subsidence of the sea floor in adjacent offshore localities are explained as consequences of coupling between erosion and sedimentation by induced flow in the lower continental crust this coupling being particularly strong due to the narrowness of the southern part of the italian peninsula numerical modelling indicates that time averaged and spatially averaged erosion rates in this region have been 0 5 mm a 1 since the early middle pleistocene less than the regional uplift rates indicating that the landscape is not in a steady state although southern italy lies within a plate boundary zone along which the african plate is subducting and within which the continental crust is extending the observed vertical crustal motions are nevertheless controlled by surface processes in particular across much of this region crustal extension is shown to be a much less important factor than onshore erosion in driving the observed rates of vertical crustal motion

the terraces of corinth gerrce a detailed record of eustatic sea level variations during the last 500 000 years abstract between corinth and xylokastro 20 marine terraces reflect the interaction of the northern peloponnese uplift and the global eustatic sea level fluctuations during the last 500 000 years correlation of the terraces with oxygen isotope records in deep sea cores allowed accurate dating of these fossilized transgressive shorelines curves of altitude versus age have been plotted they show a regular decrease of the uplift rate and a frequent return of the sea level very close to the present day one not only during the interglacial periods 5 7 9 11 13 but also during glacial periods 3 1 3 3 6 8 the alternative would be to suppose very complicated and highly improbable vertical movements of the substratum to explain the regularity of the curves the rhythm of these high sea levels is around 20 30 ka since at least 330 000 years ago

improved target illumination at ludvika mines of sweden through seismic interferometric surface wave suppression in mineral exploration new methods to improve the delineation of ore deposits at depth are in demand for this purpose increasing the signal to noise ratio through suitable data processing is an

characteristics and consequences of flow in the lower crust in some places there is strong evidence that the lower continental crust has flowed so as to smooth out variations in crustal thickness caused by differential crustal extension or shortening in order to better understand the processes involved we investigate the behavior of a fluid layer over a fluid half space to see how such a system responds to the deformation of its upper and lower boundaries this simple system can be used to study both the decay of crustal thickness contrasts and the behavior of a thin lithospheric sheet the changing response of the system to variations in density and viscosity contrasts and to different boundary conditions imposed on the fluid interface can easily be studied analytically the most important results are that variations in crustal thickness on a wavelength of a few times the thickness of the flowing channel will decay quickest and that large lateral variations in crustal thickness cause the fluid to develop a steep front which may cause a topographic step above it at the earth s surface deformation within the channel will be principally by simple shear the clear association of lower crustal flow with regions of thickened crust and magmatic activity suggests that both can reduce the viscosity of the lower crust to levels at which flow can occur the smoothing of crustal thickness contrasts leads to differential vertical motions and is thus a method by which substantial tilting can occur without faulting this differential uplift may be responsible for rotating and exhuming some of the detachment faults in metamorphic core complexes in the basin and range province of the western united states it is also a method of causing structural inversion in basins that does not require the reactivation of normal faults as thrusts or reverse faults

surface wave analysis for static corrections in mineral exploration a case study from central sweden in mineral exploration increased interest towards deeper mineralizations makes seismic methods attractive one of the critical steps in seismic processing workflows is the static correction which

seismic methods in mineral exploration and mine planning a general overview of past and present case histories and a look into the future abstractdue to high metal prices and increased difficulties in finding shallower deposits the exploration for and exploitation of mineral resources is expected to move to greater depths consequently seismic methods will become a more important tool to help unravel structures hosting mineral deposits at great depth for mine planning and exploration these methods also can be used with varying degrees of success to directly target mineral deposits at depth we review important contributions that have been made in developing these techniques for the mining industry with focus on four main regions australia europe canada and south africa a wide range of case studies are covered including some that are published in the special issue accompanying this article from surface to borehole seismic methods as well as petrophysical data and seismic modeling of mineral deposits at present high resolution 2d surveys mostly are performed in mining areas but there is a general increasing trend in the use of 3

waveform inversion of seismic velocities and attenuation from low frequency waves in cylindrical bars a new technique for laboratory measurement of seismic wave velocities and attenuation in the frequency range of 10 150 khz consists of measuring extensional waveforms using two cylindrical bars of the same material but unequal length based on the dispersion equation of the bar and rough estimates of compressional and shear velocities of the bar material the waveform measured within the shorter bar is theoretically continued to the length of the longer bar to match with the waveform measured there an inversion is then performed to minimize the phase difference between the two waveforms the velocities are obtained when the phase difference reaches a minimum at which the two waveforms attain the optimum phase match after the phase match a further inversion is performed to minimize the amplitude difference between the two waveforms to derive the extensional wave attenuation within the bar by this inversion procedure wave velocities and attenuation can be jointly determined at frequencies much lower t

deep reflection seismic imaging of iron oxide deposits in the ludvika mining area of central sweden abstract reflection seismic data were acquired within two field campaigns in the blotberget ludvika mining area of central sweden for deep imaging of iron oxide mineralization that were known to extend down to 800 850 m depth the two surveys conducted in years 2015 and 2016 one employing a seismic landstreamer and geophones connected to wireless recorders and another one using cabled geophones and wireless recorders aimed to delineate the geometry and depth extent of the iron oxide mineralization for when mining commences in the area even with minimal and conventional processing approaches the merged datasets provide encouraging information about the depth continuation of the mineralized horizons and the geological setting of the study area multiple sets of strong reflections represent a possible continuation of the known deposits that extend approximately 300 m further down dip than the known 850 m depth obtained from historical drilling they show excellent correlation in shape and strength with those of the blotberget deposits furthermore several reflections in the footwall of the known mineralization can potentially be additional resources underlying the known ones the results from these seismic surveys are encouraging for mineral exploration purposes given the good quality of the final section and fast seismic surveys employing a simple cost effective and easily available impact type seismic source

late cenozoic reorganization of the arabia eurasia collision and the comparison of short term and long term deformation rates the arabia eurasia collision deforms an area of 3 000 000 km2 of continental crust making it one of the largest regions of convergent deformation on earth there are now estimates for the active slip rates total convergence and timing of collision related deformation of regions from western turkey to eastern iran this paper shows that extrapolating the present day slip rates of many active fault systems for 3 7 million years accounts for their total displacement this result means that the present kinematics of the arabia eurasia collision are unlikely be the same as at its start which was probably in the early miocene 16 23 ma or earlier in some but not all active fault systems short term 10 year and long term 5 million year average deformation rates are consistent there is little active thickening across the turkish iranian plateau and possibly the interior of the greater caucasus these are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening and where there are structural and or stratigraphic data for pre late miocene deformation we suggest that once thick crust up to 60 km built up in the turkish iranian plateau and the greater caucasus convergence took place more easily by crustal shortening in less elevated regions such as the zagros simple folded zone the south caspian region and foothills of the greater caucasus or in other ways such as westward transport of turkey between the north and east anatolian faults the time and duration of this changeover are not known for certain and are likely be diachronous although deformation started or intensified in many of the currently active fault systems at 5 2 ma

regional heat flow in western anatolia using silica temperature estimates from thermal springs regional trends of variation of heat flow in western anatolia have been outlined using the silica temperature estimator on thermal springs silica heat flow values from 187 springs have been calculated the data are corrected for local long term mean annual surface temperature a mean value of heat flow for the western part of anatolia of 107 45 mw m 2 has been obtained which is about 60 above the world average the silica heat flow data are compared with available conventional heat flow values for this region a general agreement is observed and new patterns are recognized a close association exists between areas of high silica heat flow values above 100 mw m 2 and areas of tertiary and younger volcanism high heat flow is also observed in palaeozoic units of the menderes massif which is under tensional stress the highest heat flow estimate of 247 mw m 2 is obtained near gediz 38 57 n 29 13 2 e this area is part of a seismically active region and is located near a middle eocene subduction zone which is an area of later collision tectonics the new heat flow data from western anatolia improve our knowledge of the thermal conditions within the crust this information is important for the analysis of various geophysical and geological phenomena including seismicity

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

introduction to special issue on hard rock seismic imaging the exploration of non hydrocarbon resources is receiving increased attention worldwide particularly in terms of renewables e g geothermal energy or minerals both resources are often bound to hard rock environments which normally exhibit a strong degree of heterogeneity including faults and fractures on all scales land seismic surveys for characterizing geothermal reservoirs and mineral deposits are therefore facing the challenge of adapting the methods and tools developed for stratified sedimentary environments to strongly scattering crystalline rocks this comprises not only the pre processing of seismic data but also the imaging steps and furthermore the description and quantification of the resulting images this special issue of geophysical prospecting contains 16 papers resulting from a workshop titled hard rock seismic imaging during the 76th eage conference exhibition 2014 in amsterdam the objective of the workshop was to address all parts of the workflow from modelling and data acquisition design over data processing and imaging to interpretation general concepts and case studies were presented and the workshop attracted a large number of participants from both industry and academia from all over the world a brief introduction to the papers included in this special issue follows divided into the two main categories of the workshop mineral exploration and geothermal prospecting interested readers are also encouraged to check the two earlier special volumes on similar topics by eaton et al 2003 and the references therein and malehmir et al 2012 and the references therein

monitoring changes in velocity and q using non physical arrivals in seismic interferometry application of seismic interferometry to records from receivers at the earth s surface from sources in wells retrieves the reflection response measured at the receivers as if from virtual sources located also at the surface when the wavefields experience intrinsic losses during propagation non physical arrivals ghosts would appear in the retrieved result these ghosts appear due to waves that reflect inside a subsurface layer thus a ghost contains information about the seismic properties of the specific layer we show how such ghosts can be used to monitor layer specific changes in the velocity and intrinsic losses in the subsurface we show how to identify the ghosts using numerical modelling results from a vertical well and how to estimate the layer specific velocity and quality factor changes using numerical modelling results from a horizontal well as well as ultrasonic s wave laboratory data

climatically controlled river terrace staircases a worldwide quaternary phenomenon a comparison of fluvial terrace sequences from around the world based on data collected as part of international geoscience programme igcp project no 449 has revealed significant patterns river terraces provide important records of uplift which is essential for their formation and of landscape evolution their cyclic formation however almost invariably seems to have been a response to climatic fluctuation sequences in the european core area of igcp 449 which has the longest and most extensive research history have been used as templates for worldwide comparison there is evidence for a global acceleration of uplift at the time of and perhaps in response to the mid pleistocene revolution when climatic fluctuation switched to 100 kyr milankovitch cycles terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles subsequently river valleys became more steeply entrenched and terraces formed in response to the stronger 100 kyr climatic forcing in many cases at approximately one per cycle this paper uses the new data resource to explore differences between records in different climate zones between sequences with variable numbers of middle late pleistocene terraces and between systems in which the all important incision event has occurred in different parts of climatic cycles key records discussed include european examples from the rhine thames somme dniester dnieper don volga and aguas from asia the gediz turkey and orontes syria from north america the south platte and colorado from south africa the vaal and sundays from australia the shoalhaven and from south america the amazon paraguay and tributaries of the colorado and negro

the aegean sea we summarize briefly the main features of a kinematic model of evolution of the aegean area since 13 ma the formation of the aegean sea by extensional tectonics is related to the subduction of the mediterranean floor below the hellenic arc we then make a quantitative estimate of vertical movements in the aegean area on the basis of geological data and demonstrate that the outer arc was built since the beginning of this episode of subduction by vertical uplift the easiest way to explain the uplift is by underplating finally we discuss briefly the dynamics of the subduction marginal sea formation processes in this continental collision framework

the virtual refraction useful spurious energy in seismic interferometry seismic interferometry is rapidly becoming an established technique to recover the green s function between receivers but practical limitations in the source energy distribution inevitably lead to spurious energy in the results instead of attempting to suppress all such energy we use a spurious wave associated with the crosscorrelation of refracted energy at both receivers to infer estimates of subsurface parameters we named this spurious event the virtual refraction illustrated by a numerical two layer example we found that the slope of the virtual refraction defines the velocity of the faster medium and that the stationary phase point in the correlation gather provides the critical offset with the associated critical time derived from the real shot record this approach includes all of the necessary information to estimate wave speeds and interface depth without the need of inferences from other wave types

reflection refraction seismics in the gulf of corinth hints at deep structure and control of the deep marine basin abstract the gulf of corinth is a natural laboratory for the study of seismicity and crustal deformation during continental extension seismic profiling along its axis provides a 24 fold normal incidence seismic reflection profile and wide angle reflection refraction profiles recorded by sea bottom seismometers obs and land seismometers at wide angle incidence the land receivers document the moho at 40 km depth under the western end of the gulf north of aigion rising to 32 km depth under the northern coast in the east of the gulf both refraction and normal incidence reflection sections image the basement under the deep marine basin that has formed by recent extension the depth to the base of the sedimentary basin beneath the gulf constrained by both methods is no more than 2 7 km with 1 km of water underlain by no more than 1 7 km of sediment less than what was expected from past modeling of uplift of the south coast in the east of the gulf unlike the flat sea bottom the basement and sedimentary interfaces show topography along this axial line several deeps are identified as depocenters which suggest that this axial line is not a strike line to the basin it appears instead to be controlled by several faults oblique to the s60 e overall trend of the south coast of the gulf their more easterly strikes being consistent with the instantaneous direction of extension measured by earthquake slip vectors and by gps

the mid pleistocene climate transition onset of 100 ka cycle lags ice volume build up by 280 ka the mid pleistocene climate transition mpt is the complex climatic change which brought the late pleistocene ice ages we explore the mpt in the time and frequency domains by new methods of time series analysis high resolution oxygen isotope records reveal that the ice volume related increase in 18o mean amplitude 0 29 0 05 1 transition midpoint 922 12 ka duration 40 9 ka significantly preceded the abrupt increase in the amplitude of the 100 ka cycle at 641 9 ka this finding can be quantitatively simulated using a simple ice bedrock model in which due to the additional ice the calving threshold is exceeded the simulated calving events prior to 650 ka are separated by 77 ka whereas after 650 ka they occur pseudo periodically with a mean period of nearly 100 ka the cause for the delay of the 100 ka calving cycle was not a slow bedrock relaxation rather the coincidental combination of insolation existing ice mass and bedrock depression