quantification of the microstructural evolution of polycrystalline fabrics using fame application to in situ deformation of ice abstract in geology glaciology and material science new technological advances result in an ever increasing amount of data and datasets in particular when in situ experiments are conducted rapid rigorous and reliable statistical treatment is needed to allow researchers to access these large datasets for further analysis here we present fame fabric analyser based microstructure evaluation a suite of matlab scripts that utilize the matlab open source toolboxes mtex and polylx optional for rapid quantification of thin section data the data has been collected using an automated fabric analyser at a spatial resolution of 5 m pixel from the dataset grain maps are reconstructed and grain and grain boundary statistics are determined the same scripts calculate orientation density distribution diagrams and eigenvalues of the orientation tensor in the case of 2d in situ plane strain deformation experiments on polycrystalline heavy water d2o a matlab script based batch analysis for each deformation step was performed fame offers the possibility to generate movie files that combine optical data with c axes orientation data and grain statistics application of the presented scripts to analyse in situ deformation experiments of polycrystalline ice shows the value of rigorous quantification of the microstructural evolution data for process oriented research

structural evolution of the central part of the krusne hory erzgebirge mountains in the czech republic evidence for changing stress regime during variscan compression abstract in the central part of the krusne hory erzgebirge mountains the parautochthonous metasedimentary basement has been overthrust by a crustal nappe of fine and coarse grained orthogneisses the thrust boundary is defined by the presence of mafic eclogites with preserved subduction related fabric westward thrusting of an allochthonous unit is associated with the development of the main metamorphic foliation and lineation in non eclogitic lithologies buttressing of the allochthonous body from the west is responsible for the development of late large scale folds with n s trending hinges and vertical axial planes subsequent n s compression leads to large scale folding of both the parautochthonous and allochthonous units this deformation produces km scale antiforms with hinges plunging to the west and is associated with the development of the e w stretching lineation as a result of complete reworking of earlier fabric in the limb zones n s shortening is also associated with the development of small scale folds and brittle ductile kink bands suggesting a decrease in temperature and thus uplift of the whole studied area during this event the last stage of deformation is characterised by the development of kink band folds and a crenulation cleavage these structures suggest a sub vertical direction of principal compression developed exclusively in those parts of the area in which the n s compression produced steep planar fabric

wave attenuation over coastal salt marshes under storm surge conditions salt marshes protect coastlines against waves wave flume experiments show that marsh vegetation causes substantial wave dissipation and prevents erosion of the underlying surface even during extreme storm surge conditions

leachate detection via statistical analysis of electrical resistivity and induced polarization data at a waste disposal site northern israel landfill site is an intensely heterogeneous medium in which application of 2 d geophysical techniques frequently does not enable its accurate examination due to the lack of correlation between different geophysical profiles the study was aimed to eliminate such difficulty hereafter the leachate detection methodology is presented including 2 d smoothness constrained inversion of geoelectrical raw data collected in situ the inverted data normalization and statistical examination to eradicate influence of high heterogeneity of the landfill body the generalized statistical model of the entire site was created including the likelihood analysis of the entire normalized data set three geoelectrical parameters were involved in the analysis inversed electrical resistivity inversed chargeability ip and the ratio of inversed chargeability to inversed electrical resistivity ip res the study was combined with the synthetic modeling the analysis of bulk versus fluid electrical resistivity relationship and test borehole drillings such generalized analysis ensures independency of the results from the locality of sampling measurements it was shown that leachate detection can be correctly performed utilizing the ip res ratio while the anomaly s likelihood is higher than 90

observatory validation of neolithic tells magoules in the thessalian plain central greece using hyperspectral spectroradiometric data abstract this paper presents the results obtained from field spectroradiometric campaigns over neolithic tells magoules located at the thessalian region in greece in each one of the four archaeological sites selected three sections were carried out using the ger 1500 handheld spectroradiometer spectral profiles of the sections and several vegetation indices such as normalized difference vegetation indices ndvi and simple ratio sr have been examined in this study this is one of the first times that ground hyperspectral data are evaluated in such context of archaeological research for the spectral characterization of archaeological features as it was found ground spectroradiometric measurements can be efficiently used in order to support and validate satellite imagery results for the detection of archaeological sites

variscan tectonics of central europe postaccretionary intraplate deformation of weak continental lithosphere the area occupied by the variscan belt of central europe forms part of gondwana derived microplates essentially avalonia and armorica that according to paleomagnetic data juxtaposed baltica and laurentia from the upper ordovician to the lower devonian the actual structure of this area is a puzzle of rather small fault bounded crustal blocks different in p t t histories which was created by later tectonic processes at around 360 to 320 ma according to a common view and by contrast to paleomagnetic data the structural record of fault bounded blocks is interpreted in terms of mid devonian to lower carboniferous amalgamation of narrow continental plates represented by the fault bounded blocks themselves however this is not supported in this article instead it will be shown that fault systems and fault bounded blocks were created by intraplate deformation of a weak domain of gondwana derived continental lithosphere significantly after its accretion deformation was partitioned into newly formed deep seated strike slip and kinematically connected reverse or normal detachment systems large translation magnitudes caused juxtaposition of crustal areas of variable thickness until they were emplaced along the fault systems the various categories of fault bounded complexes record different tectonic events category 1 metamorphic complexes represent deep seated parts of thickened crust some time before unroofing on the detachment systems between about 340 360 and 320 ma however the record of subduction and extreme crustal thickening during earlier stages of the collision history was erased to a high degree and is only preserved by mineral and structural relics strike slip and detachment systems propagated across and dismembered tectonic boundaries formed during these early events category 2 metamorphic complexes and the barrandian basin recording predominant pre late devonian metamorphic or stratigraphic events represent the brittle upper crustal parts during continuing metamorphism in the category 1 complexes weakly or unmetamorphosed lower paleozoic category 3 basins represent areas of thinned continental crust and record subsidence before and to some degree during activity of detachment systems the complex overall kinematic pattern of block bounding strike slip and detachment systems indicates compression and extension acting simultaneously this probably reflects the effects of continuing oblique plate convergence rotation and wsw extrusion of fault bounded blocks in addition to heating and extensional flow of previously thickened crustal areas

the use of watershed segmentation and gis software for textural analysis of thin sections textural analysis of thin sections of rocks can be performed with a geographic information system gis program to improve management and visualisation of data automatic detection of grain edges is performed by watershed segmentation on digital pictures of the thin section after vectorization of the segmented picture the resulting map of grain boundaries is edited and corrected manually gis software allows the user to associate each grain with attributes such as phase name position size aspect ratio orientation and convexity the grains can then be classified according to one or several attributes the spatial distribution of the different classes of grains can be visualised with colour coded maps or quantified by cluster analysis a weakly foliated quartzite and an igneous cumulate are taken as examples to show how invisible patterns are made evident with these kinds of maps the interpretation of these spatial distributions remains problematic but future development of 2d or 3d numerical models of textural evolution makes this technique promising

tidal residual intertidal mudflat trim model and its applications to san francisco bay california abstract a numerical model using a semi implicit finite difference method for solving the two dimensional shallow water equations is presented the gradient of the water surface elevation in the momentum equations and the velocity divergence in the continuity equation are finite differenced implicitly the remaining terms are finite differenced explicitly the convective terms are treated using an eulerian lagrangian method the combination of the semi implicit finite difference solution for the gravity wave propagation and the eulerian lagrangian treatment of the convective terms renders the numerical model unconditionally stable when the baroclinic forcing is included a salt transport equation is coupled to the momentum equations and the numerical method is subject to a weak stability condition the method of solution and the properties of the numerical model are given this numerical model is particularly suitable for applications to coastal plain estuaries and tidal embayments in which tidal currents are dominant and tidally generated residual currents are important the model is applied to san francisco bay california where extensive historical tides and current meter data are available the model calibration is considered by comparing time series of the field data and of the model results alternatively and perhaps more meaningfully the model is calibrated by comparing the harmonic constants of tides and tidal currents derived from field data with those derived from the model the model is further verified by comparing the model results with an independent data set representing the wet season the strengths and the weaknesses of the model are assessed based on the results of model calibration and verification using the model results the properties of tides and tidal currents in san francisco bay are characterized and discussed furthermore using the numerical model estimates of san francisco bay s volume surface area mean water depth tidal prisms and tidal excursions at spring and neap tides are computed additional applications of the model reveal qualitatively the spatial distribution of residual variables

the spatial distribution of grains and crystals in rocks characterisation and analysis of the spatial distribution pattern sdp of grains or crystals in rocks is potentially a powerful technique which can be used to constrain the processes which operate in the formation of rocks a method to quantify the sdp of grains in thin section is presented the distance betwen the centre of a grain and the centre of its nearest neighbour is calculated for all the grains in the sample area to produce a distribution of distances that characterises the spatial pattern of grains in the rock this distribution is then normalised to a random distribution of points with the same population density to give a descriptive value r values of r for rock samples are plotted against porosity modal abundance of other phases in igneous and metamorphic rocks to characterise the sdp the sdp of randomly packed distributions of equal size spheres varies systematically with porosity producing a line on a porosity versus r plot termed the random sphere distribution line rsdl rocks which plot above the rsdl have an ordered sdp and those that plot below a clustered sdp the effects of variation in grain packing order grain sorting compaction and random crystallisation overgrowth on determined r values were investigated using a combination of 3 d sphere models and 2 d texture models the maximum possible value of r is 2 148 corresponding to a perfect section through hexagonal cubic close packing of grains the minimum value of r is dependent on the proportion of grains in the sample volume and may be as low as 1 2 for a sample volume with 30 grains which are clustered variations in size sorting can cause r to vary by approximately 0 25 mechanical compaction of a loose framework of grains results in a higher packing order and an increase in r continued compaction creates a fabric in the texture and r decreases as cluster patterns are developed perpendicular to the principal stress the overgrowth of grains in a touching framework alters the location of the geometric grain centre as the crystal shape changes leading to an increase in r as porosity decreases results reveal that grain sorting compaction and grain overgrowth produce different r versus porosity relationships which can be identified in and therefore used to constrain the relative importance of these processes in rock samples

the lower zone critical zone transition of the bushveld complex a quantitative textural study the lower zone critical zone boundary of the bushveld complex is an intrusion wide major stratigraphic transition from ultramafic harzburgite and pyroxenite in the lower zone to increasingly plagioclase richpyroxenitesandnoritesinthecriticalzone quantitative textural and compositional data for 29 samples through this transition show the following lower zone orthopyroxene grains are larger have higher aspect ratios are better foliated and have a lower trapped liquid component than those of the critical zone the larger grain size of the lower zone results in crystal size distribution plots that are rotated to lower slopes and intercepts relative to those in the critical zone although all rocks show differing amountsoffoliation mineral lineations are weak to absent these data are consistent with significant compaction driven recrystallization in the study section numerical modeling of concurrent compaction and crystallization provides a quantitative model of how the lower zone critical zone transition may have formed plagioclase is rare in the lower zone because compaction removes interstitial liquid before it reaches plagioclasesaturation however asthecrystalpilegrows plagioclase saturation is reached in the interstitial liquid before compaction is complete in more evolved pyroxenites producing more abundant but still modest amounts of plagioclase characteristic of the lower critical zone it is concluded that both the textures and the modal mineralogy are largely controlled by compaction and compactiondriven recrystallization primary magmatic textures are not preserved

contrasting textures in metamorphic and anatectic migmatites an example from the scottish caledonides a method for the quantitative analysis of the spatial relations of minerals is described dispersed distributions are formed by annealing and destroyed in post tectonic migmatization aggregate distributions characterize solid state differentiation whereas leucosomes formed in systems of high fluid rock ratio in the examples studied anatectic melts show random distributions quantitative textural analysis can be used to indicate whether migmatization was post tectonic or earlier though caution is necessary if post migmatite cooling is slow or if there is some minor deformation more importantly it can be used to discriminate melt present from melt absent leucosomes this is exemplified by a suite of metamorphic and anatectic migmatites from the scottish caledonides the textural evolution of anatexites with increasing melt percentage is traced initial feldspar porphyroblastesis occurs by ostwald ripening via grain boundary melts subsequently ophthalmites develop with fabrics and chemistry inherited from the palaeosome at greater than 30 melt these inherited fabrics are wholly destroyed deformation prompts segregation into melanosome and leucosome resultant leucosomes contain no inherited crystals the scale of anatectic systems is fixed at the point at which segregation begins ophthalmites provide evidence for melt and crystal transfer beyond original palaeosome boundaries in contrast metamorphic migmatites are necessarily small scale systems because of diffusive constraints and melanosomes are invariably produced

fabric analysis using the intercept method abstract the intercept method is a convenient yet powerful method for the numerical analysis of fabrics for geological applications it can be used when a set of objects e g pores grains or aggregates of a specific mineral lineaments etc with unique characteristics can be identified in an image the intercept method analyses boundaries of objects as a population of lines how intercepts are definined is therefore important in order to establish the significance of the intercept counts when the method is applied to digital images the subdivision of the information into square pixels must also be considered we apply a linear filter which minimizes the effects of grid anisotropy on the counting of intercepts analysis of the resulting rose of intercept counts by a fourier series considerably facilitates the interpretation of the data a rose of directions can readily be derived for the phase boundaries if a population of objects can be assumed to have started with an originally isotropic orientation and to have been deformed passively the fourier components of the rose of intercepts also give the sectional strain the fourier components also permit an objective test of the validity of describing a fabric as resulting from a homogeneous strain on an initially isotropic section two computer programs for the counting and analysis of intercepts on digital images are presented and applied in four examples which illustrate the usefulness of the intercept method for magmatic fabric measurement strain analysis and lineament analysis we also illustrate the importance of fourier series decomposition of rose of intercept counts for fabric interpretations intercept results are also shown to be compatible with those derived by other methods eigenvector surfor inertia tensor autocorrelation methods

comparison of sediment supply to san francisco bay from watersheds draining the bay area and the central valley of california article i nfo quantifying suspended sediment loads is important for managing the world s estuaries in the context of nav igation pollutant transport wetland restoration and coastal erosion to address these needs a comprehen sive analysis was completed on sediment supply to san francisco bay from fluvial sources suspended sediment optical backscatter velocity data near the head of the estuary and discharge data obtained from the output of a water balance model were used to generate continuous suspended sediment concentration records and compute loads to the bay from the large central valley watershed sediment loads from small tributary watersheds around the bay were determined using 235 station years of suspended sediment data from 38 watershed locations regression analysis and simple modeling over 16 years net annual suspended sediment load to the head of the estuary from its 154 000 km 2 central valley watershed varied from 0 13 to

variszische duktile tektonik im bohmischen massiv die verformungsanalyse und richtungsverteilung der streckungslineationen in den duktilen bereichen des bohmischen massiv zusammen genommen mit der lage der foliationsflachen deuten darauf hin das die blattverschiebungen wahrend der variszischen deformation die entscheidende rolle gespielt haben die kompatibilitat der deformation im gesamtbereich wurde durch uberschiebungen und transpression in den durch die blattverschiebungen begrenzten blocke erreicht das variszische tektogen wurde als blattverschiebungsorogen auf einer kontinentalen oberproterozoischen kruste angelegt die zonen mit intensiver krustenverkurzung und damit groster krustenmachtigkeit sind durch weitraumige anatexis und granitische intrusionen gekennzeichnet

automatic grain boundary detection and grain size analysis using polarization micrographs or orientation images abstract a simple procedure for creating grain boundary maps from petrographic thin sections termed the lazy grain boundary lgb method has been devised it is based on a set of macro commands programmed for nih image a public domain image processing software the grain boundary detection is based on gradient filtering the procedure makes use of multiple input images sets of regular polarized micrographs or where possible orientation misorientation images on each image of a given input set only the most significant grain boundaries are detected and by combining those a single grain boundary map is obtained image models and criteria for grain boundary identification are discussed briefly the principal aim of the lgb method is to facilitate the production of large grain boundary maps containing several thousand cross sectional areas to provide statistically valid samples for grain size analysis a section of black hills quartzite was used to test the lgb method five different input sets were prepared and used for automatic lgb analysis one set was additionally used for an interactive analysis and for a manual tracing from all seven grain boundary maps the 2 and 3 d grain size distributions were calculated the results are compared and the different image sets and procedures are rated for precision over and undersegmentation and speed of preparation

the importance of combined tidal and meteorological forces for the flow and sediment transport on intertidal shoals estuarine intertidal areas are shaped by combined astronomical and meteorological forces this paper reveals the relative importance of tide surge wind and waves for the flow and sediment transport on large intertidal shoals results of an intensive field campaign have been used to validate a numerical model of the roggenplaat intertidal shoal in the eastern scheldt estuary the netherlands in order to identify and quantify the importance of each of the processes over time and space we show that its main tidal creeks are not the cause for the dominant direction of the net flow on the shoal the tidal flow over the shoal is steered by the water level differences between the surrounding channels also during wind events the tidal flow enhanced by surge is dominant in the creeks in contrast wind speeds of order 40 times the typical tidal flow velocity are sufficient to completely alter the flow direction and magnitude on an intertidal shoal this has significant consequences for the sediment transport patterns apart from this wind driven flow dominance during these events the wind also increases the bed shear stress by waves for the largest intertidal part of the roggenplaat only 1 10 of the yearly transport results from the 50 least windy tides even if the shoal is artificially lowered half the tidal range this dominance of energetic meteorological conditions in the transports matches with field observations in which the migration of the creeks and high parts of the shoal are in line with the predominant wind direction

a numerical comparison of 2d resistivity imaging with 10 electrode arrays numerical simulations are used to compare the resolution and efficiency of 2d resistivity imaging surveys for 10 electrode arrays the arrays analysed include polepole pp pole dipole pd half wenner hw wenner wn schlumberger sc dipole dipole dd wenner wb array gm multiple or moving gradient array gd and midpoint potential referred measurement mpr arrays five synthetic geological models simulating a buried channel a narrow conductive dike a narrow resistive dike dipping blocks and covered waste ponds were used to examine the surveying efficiency anomaly effects signal to noise ratios and the imaging capabilities of these arrays the responses to variations in the data density and noise sensitivities of these electrode configurations were also investigated using robust l1 norm inversion and smoothness constrained least squares l2 norm inversion for the five synthetic models the results show the following i gm and wn are less contaminated by noise than the other electrode arrays ii the relative anomaly effects for the different arrays vary with the geological models however the relatively high anomaly effects of pp gm and wb surveys do not always give a high resolution image pd dd and gd can yield better resolution images than gm pp wn and wb although they are more susceptible to noise contamination sc is also a strong candidate but is expected to give more edge effects iii the imaging quality of these arrays is relatively robust with respect to reductions in the data density of a multi electrode layout within the tested ranges iv the robust inversion generally gives better imaging results than the l2 norm inversion especially with noisy data except for the dipping block structure presented here v gd and mpr are well suited to multichannel surveying and gd may produce images that are comparable to those obtained with dd and pd accordingly the gd pd dd and sc arrays are strongly recommended for 2d resistivity imaging where the final choice will be determined by the expected geology the purpose of the survey and logistical considerations

porphyroclast systems as kinematic indicators porphyroclasts of relatively strong minerals in mylonites commonly have an internal monoclinic shape symmetry defined by tails of dynamically recrystallized material the geometry of a porphyroclast and its tails called a porhyroclast system can serve as a valuable indicator of the sense of vorticity porphyroclast systems have been divided into and types on the basis of the geometry of the tails types have wedge shaped recrystallized tails whose median lines lie on opposite sides of a reference plane parallel to the tails and containing the symmetry axis for the system types are further subdivided into a a types in which the porphyroclast is isolated in a relatively homogeneous matrix and b types in which the porphyroclast system is associated with a shear band foliation in the matrix types typically have narrow recrystallized tails whose median lines cross the reference plane adjacent to the porphyroclast consequently embayments of matrix material occur adjacent to the porphyroclasts and the tails display characteristic bends a porphyroclast system in a mylonite develops when the relatively weak dynamically recrystallized grain aggregate in the porphyroclast mantle changes its shape due to non coaxial flow in the adjacent matrix this behaviour has been modelled in shear box experiments passive marker lines around rigid cylinders embedded in silicone putty were subjected to simple shear the experiments were modified to simulate a change in recrystallization rate r with respect to rate of deformation by decreasing the diameter of the rigid cylinder during deformation at variable rates the ratio r appears to be one of the most important factors in determining which porphyroclast system will develop at high r values flow of recrystallized material away from the porphyroclast is continuously appended by the production of new grains and wedge shaped a type tails develop at low r values relatively few new grains are added to the tails which become thinned and deflected by drag due to the spinning motion of the porphyroclast in addition most porphyroclast systems at low shear strains are of a type or lack monoclinic symmetry whereas types are only developed at high shear strain values complex porphyroclast systems characterized by two generations of tails are observed in many of the natural and model shear zones studied and may form due to fluctuating r conditions that allow isolated a and type porphyroclast systems to be used as sense of vorticity indicators are the systems should have a monoclinic shape symmetry matrix grain size should be small with respect to porphyroclast size matrix fabric should be homogeneous deformation history should be simple and observations should be made on sections normal to the inferred bulk vorticity vector for the mylonite

forearc deformation and strain partitioning during growth of a continental magmatic arc the northwestern margin of the central bohemian plutonic complex bohemian massif abstract the late devonian subduction followed by the early carboniferous continental collision of the saxothuringian and overriding upper crustal tepla barrandian units led to the growth of a large magmatic arc the 354 337 ma central bohemian plutonic complex in the central part of the bohemian massif far field tectonic forces resulting from the collision produced wnw ese to nw se regional shortening across the forearc upper crust above the subduction zone the shortening was accommodated by predominantly top to the ese tectonic transport along the southeastern flank of the tepla barrandian unit approaching the magmatic arc margin the regional structural pattern changes and exhibits significant across and along strike variations interpreted as a result of strain partitioning where the saxothuringian tepla barrandian convergence interacted in different ways with the intruding magma pulses around the voluminous northeasterly 354 ma sazava pluton the principal shortening was at high angle to the forearc facing intrusive contact and the host rocks were significantly thermally softened the regional top to the ese tectonic transport converted here into arc parallel ductile flow within the structural aureole around and above the pluton in contrast a narrow to nonexistent ductile strain aureole is preserved in the host rocks around discordant sheet like plutons the southwesterly pre 354 ma marginal granite and the milin granodiorite of unknown radiometric age our ams study of the marginal granite and milin granodiorite and mapping of mesoscopic magmatic foliations and lineations in another neighboring sheet like pluton the 346 ma kozarovice granodiorite reveals sigmoidal map scale fabric patterns consistent with dextral transpression we thus suggest that the thin sheet like plutons were oriented obliquely to the principal shortening and were rheologically weaker than the host rocks prior to final crystallization producing dextral transpression recorded by the internal fabrics of these plutons our study shows that the far field plate kinematics during pluton emplacement is not the only factor that controls strain partitioning in continental magmatic arcs the two contrasting styles of pluton emplacement documented here indicate that the pluton shape orientation of intrusive contacts with respect to the background plate convergence vector and heat budget of intrusions magma volume composition and proportion of hot mantle component may also govern strain partitioning

marine electrical resistivity tomography for shipwreck detection in very shallow water a case study from agropoli salerno southern italy abstract a marine electric resistivity survey was carried out over a submerged beach along the agropoli shore salerno italy to detect buried objects of archaeological interest below the sandy seabed we found a shipwreck a military vessel that probably sunk during the salerno landing operations of the allied forces in the second world war resistivity data provide information on the vertical and horizontal extension of the shipwreck which is characterized by very low calculated resistivity values about 2 5 ohm m such values differ significantly from the sand and the bedrock values 5 40 ohm m although the presence of the shipwreck is clearly visible from geoelectric data the joint application of electric magnetic and multibeam bathymetric techniques reduces the ambiguities inherent in each method as shown in the electrical resistivity tomography ert and confirmed by the digital elevation model obtained from the processing of bathymetric data the shipwreck extends more than 30 m in ne sw direction and it is about 13 m wide the global extension of the relic is consistent with the magnetic data that are characterized by a magnetic anomaly with an amplitude of about 1800 nt and similar dimension as inferred from the estimation of source boundaries obtained from the computation of the analytic signal the results of our survey encourage the use of marine geoelectrical methods for the detection of buried archaeological targets particularly in locations where the use of seismic prospecting is not effective e g very shallow water with sandy sea bottoms the integration of different geophysical methods allows to better define the extension depth and thickness of buried objects suggesting that such an approach is the most effective for underwater archaeological investigations

quantifying tomb geometries in resistivity images using watershed algorithms abstract quantifying the geometries defined here as width height and depth of burial of archeological structures within resistivity models produced as a result of the regularization constraints used in most inversion algorithms is difficult especially when structures are closely spaced here we apply the watershed by simulated immersion method of boundary detection to smooth 2d resistivity images generated for synthetic and field data over 3d targets the synthetic studies include a single cavity model a model for two widely spaced cavities spacing unit electrode spacing and a model for two closely spaced cavities spacing

geophysical investigation of the temple of apollo hierapolis turkey abstract the ruins of hierapolis are located a few kilometres north of laodicea in the lycus valley western turkey this area is characterised by a large geothermic field that produces several hot water springs along tectonic structures fractures and faults inside hierapolis is the temple of apollo the principal deity of the city while the foundations of this temple go back to late hellenistic times the present remains of the upper structure are from the 3rd century ad next to it there is an underground chamber called the plutonion from which poisonous gases emerge this paper presents the results of a geophysical survey carried out to explore firstly the buried cavities or structures beneath the temple of apollo knowledge of which is important to understand whether the plutonion could be entered from the inside of the temple for completing the sacrifices secondly to contribute to the ongoing evaluation of ground penetrating radar gpr and electrical resistivity tomography ert as tools for research into subsurface archaeological features voids walls etc two dimensional ert imaging was used to detect the presence of an active normal fault passing under the temple of apollo as shown by geological geomorphological and archaeoseismological observations the resistivity profiles reveal the presence of conductive material clay covering the archaeological structures the presence of active normal faults is indicated by the displacement of the bedrock and the conductive material on top of it three dimensional gpr imaging was used to detect man made structures located under the temple of apollo the results of the two survey methods applied were compared assessing the relative merits and demerits of each technique their combined use is discussed in terms of providing enhanced views that are more informative than a single method

the differences in morphological development between the intertidal flats of the eastern and western scheldt human interventions have a large impact on estuarine morphology the intertidal flats in the eastern scheldt and western scheldt estuaries the netherlands have faced substantial morphological changes over the past decades these changes are thought to be caused by human interventions such as the construction of the storm surge barrier in the mouth of the eastern scheldt and the deepening of the navigation channels of the western scheldt this paper analyses several datasets and numerical simulations of hydrodynamics providing an overview of the various morphological characteristics of the intertidal flats in the two estuaries over time and space apart from the volume area and average height of these areas also the integral steepness of each flat is quantified based on its full geometry the analyses focus on the intertidal flats surrounded by water which allows for a robust comparison between the different flats the intertidal flats in the western scheldt appear to be substantially steeper compared to those in the eastern scheldt the data indicates that a larger average height of a flat is related to a larger steepness despite variations in the evolution of the different flats distinct characteristics of both estuaries are observed an opposed trend is identified over time the flats in the western scheldt have mainly increased in height whereas the flats in the eastern scheldt have lowered after the completion of the storm surge barrier this opposing development is associated with differences in tidal flow velocities in the estuaries which are the result of human interventions

strain and shape fabric variations associated with ductile shear zones abstract the foliated and compositionally banded granitic orthogneisses in the central core of the maggia nappe a lower pennine basement nappe of the central swiss alps are shown to be the sheared equivalent of late hercynian age granitic intrusions these ductile shear zones show mineral assemblages in amphibolite facies are alpine in age and form an anastomosing network enclosing remnant lozenge shaped pods of relatively undeformed rock the foliation developed within the shear zones concomitantly with a change in shape of quartz grain aggregates from initially equidimensional through tear drop shapes to ribbon like aggregates these shape changes occurred by intracrystalline glide together with intercrystalline slip on deformation induced planar surfaces

sediment transport in the san francisco bay coastal system an overview abstract the papers in this special issue feature state of the art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal estuarine systems here we focus on the san francisco bay coastal system extending from the lower san joaquin sacramento delta through the bay and along the adjacent outer pacific coast san francisco bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries including a mining legacy channel dredging aggregate mining reservoirs freshwater diversion watershed modifications urban run off ship traffic exotic species introductions land reclamation and wetland restoration the golden gate strait is the sole inlet connecting the bay to the pacific ocean and serves as the conduit for a tidal flow of 8 10 9 m 3 day in addition to the transport of mud sand biogenic material nutrients and pollutants despite this physical biological and chemical connection resource management and prior research have often treated the delta bay and adjacent ocean as separate entities compartmentalized by artificial geographic or political boundaries the body of work herein presents a comprehensive analysis of system wide behavior extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining impact research of g k gilbert in the early 20th century

tracking tracer motion in a 4 d electrical resistivity tomography experiment a new framework for automatically tracking subsurface tracers in electrical resistivity tomography ert monitoring images is presented using computer vision and bayesian inference techniques in the form of a kalman filter the trajectory of a subsurface tracer is monitored by predicting and updating a state model representing its movements observations for the kalman filter are gathered using the maximally stable volumes algorithm which is used to dynamically threshold local regions of an ert image sequence to detect the tracer at each time step the application of the framework to the results of 2 d and 3 d tracer monitoring experiments show that the proposed method is effective for detecting and tracking tracer plumes in ert images in the presence of noise without intermediate manual intervention

estimating 3d variation in active layer thickness beneath arctic streams using ground penetrating radar we acquired three dimensional 3d ground penetrating radar gpr data across three stream sites on the north slope ak in august 2005 to investigate the dependence of thaw depth on channel morphology data were migrated with mean velocities derived from multi offset gpr profiles collected across a stream section within each of the 3d survey areas gpr data interpretations from the alluvial lined stream site illustrate greater thaw depths beneath riffle and gravel bar features relative to neighboring pool features the peat lined stream sites indicate the opposite greater thaw depths beneath pools and shallower thaw beneath the connecting runs results provide detailed 3d geometry of active layer thaw depths that can support hydrological studies seeking to quantify transport and biogeochemical processes that occur within the hyporheic zone

estimating depth of investigation in dc resistivity and ip surveys in this paper the term depth of investigation refers generically to the depth below which surface data are insensitive to the value of the physical property of the earth estimates of this depth for dc resistivity and induced polarization ip surveys are essential when interpreting models obtained from any inversion because structure beneath that depth should not be interpreted geologically we advocate carrying out a limited exploration of model space to generate a few models that have minimum structure and that differ substantially from the final model used for interpretation visual assessment of these models often provides answers about existence of deeper structures differences between the models can be quantified into a depth of investigation doi index that can be displayed with the model used for interpretation an explicit algorithm for evaluating the doi is presented the doi curves are somewhat dependent upon the parameters used to generate the different models but the results are robust

plagioclase chain networks in slowly cooled basaltic magma plagioclase crystals in the slowly cooled interior of the thick holyoke flood basalt flow of connecticut linked to form monomineralic chains at an early crystallization stage partial melting experiments reveal that when the quartz tholeiite was only 25 crystallized the chains had already linked to form a continuous 3 d network at such an early stage of crystallization the network was weak highly permeable and easily deformed consequently the mush of plagioclase chains and interstitial pyroxene crystals underwent compaction in the lower third of the flow with the expelled liquid rising to the center of the flow where it crystallized to form coarse grained sheets of fractionated basalt plagioclase chains are most easily seen in the basalt after it has been partly melted and the late crystallizing minerals converted to glass the chains are several crystals wide the crystals which are approximately 0 5 mm long are attached together randomly normal zoning patterns indicate crystals had a brief period of growth before linking together the chains branch every few millimeters to form the 3 d network which was mapped using serial polished sections and x ray ct scans the chain frequency measured along vertical and horizontal traverses decreases toward the center of the flow in the compaction zone the frequency in the vertical direction is greater than in the horizontal making the reasonable assumption that these frequencies were initially the same the difference is used to calculate the degree of compaction the resulting pattern through the flow matches almost exactly the pattern indicated by variations in the incompatible elements plagioclase chains are also found in some coarser grained plutonic rocks if they are common their fabric may provide a new direct means of measuring the degree of compaction in crystal mushes

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

electrical resistivity tomography to investigate geological structures of the earth s upper crust it is important to have detailed knowledge of the electrical properties of the earth s crust in order to recognize geological structures and to understand tectonic processes in the area surrounding the german continental deep drilling project ktb we have used dc dipole dipole soundings to investigate the electrical conductivity distribution down to a depth of several kilometres we have adapted the electrical resistivity tomography ert technique a well established near surface method to large scale experiments independent transmitting and receiving units were used to realize the concept of simultaneous multichannel registration of the scalar electrical potential at 44 dipoles the measured data yielded apparent resistivities which were inverted to a 2d resistivity model ranging from the surface down to a depth of 4 km two highly conductive structures with steep inclination were detected they are expected to be major fault zones embedded in a metamorphic body the rather low resistivity 10 m can be explained by the existence of graphitic minerals and or electrolytic fluids

an extension of the saltykov method to quantify 3d grain size distributions in mylonites abstract the estimation of 3d grain size distributions gsds in mylonites is key to understanding the rheological properties of crystalline aggregates and to constraining dynamic recrystallization models this paper investigates whether a common stereological method the saltykov method is appropriate for the study of gsds in mylonites in addition we present a new stereological method named the two step method which estimates a lognormal probability density function describing the 3d gsd both methods are tested for reproducibility and accuracy using natural and synthetic data sets the main conclusion is that both methods are accurate and simple enough to be systematically used in recrystallized aggregates with near equant grains the saltykov method is particularly suitable for estimating the volume percentage of particular grain size fractions with an absolute uncertainty of 5 in the estimates the two step method is suitable for quantifying the shape of the actual 3d gsd in recrystallized rocks using a single value the multiplicative standard deviation msd parameter and providing a precision in the estimate typically better than 5 the novel method provides a msd value in recrystallized quartz that differs from previous estimates based on apparent 2d gsds highlighting the inconvenience of using apparent gsds for such tasks

chronological and geochemical constraints on the pre variscan tectonic history of the erzgebirge saxothuringian zone abstract a combined u pb zircon geochronological and whole rock isotopic and geochemical study has been carried out on high grade orthogneiss meta basite and meta sediments from the erzgebirge the results indicate multiple pulses of ediacaran ordovician magmatism in a transitional volcanic arc to rift basin setting orthogneiss from high pressure nappes exhibit a step like pattern of inherited zircon ages and emplacement ages of 500 475 ma in contrast granite gneiss from the medium pressure core of the erzgebirge is characterised by three pulses of magmatism in the early cambrian late cambrian and early ordovician a trend of decreasing th u ratios in zircon is observed to c 500 ma after which significant increases in the trend and variability of the data is inferred to mark the transition from arc related to rift related magmatism sediments deposited in the early cambrian have continental island arc affinity major detrital peaks in the ediacaran and subordinate tonian palaeoproterozoic and neoarchaean data are consistent with an avalonian cadomian arc and west african craton derivation the early cambrian sediments were locally reworked by a thermal event in the ordovician resulting in leucocratic banding and recorded in ordovician zircon rims characterised by systematically lower th u ratios ptygmatically folded leucocratic bands containing ordovician zircon rims associated with low th u ratios are further observed in the granite gneiss core of the erzgebirge variscan ages are rare except in a fine grained high pressure micaschist which contains exclusively small structure less zircon with a weighted mean age of 350 2 ma these data along with a re evaluation of previously published data have been interpreted as the product of flattening subduction during the early cambrian followed by the opening of slab windows in the late cambrian and finally delamination in the early ordovician delamination of the orphaned slab led to asthenospheric upwellings triggering extension bimodal magmatic pulses recycling of fertile crust high temperature metamorphism and cratonisation of relatively young crust

from geometry to dynamics of microstructure using boundary lengths to quantify boundary misorientations and anisotropy the microstructure of a quartzite experimentally deformed and partially recrystallised at 900 jc 1 2 gpa confining pressure and strain rate 10 6 s was investigated using orientation contrast and electron backscatter diffraction ebsd boundaries between misoriented domains grains or subgrains were determined by image analysis of orientation contrast images in each domain ebsd measurements gave the complete quartz lattice orientation and enabled calculation of misorientation angles across every domain boundary results are analysed in terms of the boundary density which for any range of misorientations is the boundary length for that range divided by image area this allows a more direct comparison of misorientation statistics between different parts of a sample than does a treatment in terms of boundary number the strain in the quartzite sample is heterogeneous a 100 150 am low strain partially recrystallised subarea c was compared with a high strain completely recrystallised subarea e the density of high angle 10j boundaries in e is roughly double that in c reflecting the greater degree of recrystallisation low angle boundaries in c and e are produced by subgrain rotation in the low angle range 0 10j boundary densities in both c and e show an exponential decrease with increasing misorientation the densities scale with exp h k where k is approximately 2j in c and 1j in e in other words e has a comparative dearth of boundaries in the 8 10j range we explain this dearth in terms of mobile high angle boundaries sweeping through and consuming low angle boundaries as the latter increase misorientation through time in e the density of high angle boundaries is larger than in c so this sweeping would have been more efficient and could explain the relative paucity of 8 10j boundaries the boundary density can be generalised to a directional property that gives the degree of anisotropy of the boundary network and its preferred orientation despite the imposed strain the analysed samples show that boundaries are not on average strongly aligned this is a function of the strong sinuosity of high angle boundaries caused by grain boundary migration low angle boundaries might be expected on average to be aligned in relation to imposed strain but this is not found

crystallization processes in migmatites an important prerequisite for interpreting microstructures in plutonic and metamorphic rocks is understanding crystallization processes this study uses crystal size distribution csd and grain shape parameters to investigate mineral reaction controlled crystal growth and melt solidification in migmatites of the bayerische wald variscan orogeny germany partially molten rocks were studied because they allow the simultaneous investigation of crystallization of a melt and the growth of solid products of a metamorphic reaction csd and shape factors were obtained for three different minerals 1 cordierite in a diatexite where the melt remained in the system 2 k feldspar in a segregated k feldspar quartz leucosome and 3 plagioclase from a segregated plagioclase quartz leucosome cordierite crystals exhibit a nearly linear csd pattern and subeuhedral crystal shapes k feldspar grains display an approximately linear csd except for a marked increase at large crystal size classes k feldspar grains are characterized by strongly lobate grain boundaries the csd of plagioclase crystals is nearly linear with a slight decrease at small crystal size classes plagioclase shape factors also indicate lobate grain boundaries however with lower values than k feldspar cordierite csd and shape data are consistent with interface controlled crystallization the csd indicates that nucleation and growth is the rate limiting step during the cordierite producing reaction in contrast to porphyroblast growth in solid rocks where mass transfer is typically rate limiting csd combined with information on the duration of crystallization yields growth rates of 10 17 to 10 18 m s the plagioclase data are consistent with magmatic crystallization and are well described by the communicating neighbor theory the k feldspar data also indicate magmatic crystallization the overproduction of large grains of k feldspar reflects the interplay between nucleation and growth rates at the initial stage of crystallization because of different environments between solid and anatectic rocks the csd may help to decipher metamorphic from anatectic migmatites

reply to comments by a krohe and a p willner on structural evolution of the central part of the krusne hory erzgebirge mountains in the czech republic evidence for changing stress regime during variscan compression journal of structural geology 23 2001 1373 1392

cross hole resistivity tomography using different electrode configurations this paper investigates the relative merits and effectiveness of cross hole resistivity tomography using different electrode configurations for four popular electrode arrays pole pole pole bipole bipole pole and bipole bipole by examination of two synthetic models a dipping conductive strip and a dislocated fault it is shown that besides the popular pole pole array some specified three and four electrode configurations such as pole bipole am n bipole pole am b and bipole bipole am bn with their multispacing cross hole profiling and scanning surveys are useful for cross hole resistivity tomography these configurations compared with the pole pole array may reduce or eliminate the effect of remote electrodes systematic error and yield satisfactory images with 20 noise contaminated data it is also shown that the configurations which have either both current electrodes or both potential electrodes in the same borehole i e pole bipole a mn bipole pole ab m and bipole bipole ab mn have a singularity problem in data acquisition namely low readings of the potential or potential difference in cross hole surveying so that the data are easily obscured by background noise and yield images inferior to those from other configurations

testing random forest classification for identifying lava flows and mapping age groups on a single landsat 8 image abstract mapping lava flows using satellite images is an important application of remote sensing in volcanology several volcanoes have been mapped through remote sensing using a wide range of data from optical to thermal infrared and radar images using techniques such as manual mapping supervised unsupervised classification and elevation subtraction so far spectral based mapping applications mainly focus on the use of traditional pixel based classifiers without much investigation into the added value of object based approaches and into advantages of using machine learning algorithms in this study nyamuragira characterized by a series of 20 overlapping lava flows erupted over the last century was used as a case study the random forest classifier was tested to map lava flows based on pixels and objects image classification was conducted for the 20 individual flows and for 8 groups of flows of similar age using a landsat 8 image and a dem of the volcano both at 30 meter spatial resolution results show that object based classification produces maps with continuous and homogeneous lava surfaces in agreement with the physical characteristics of lava flows while lava flows mapped through the pixel based classification are heterogeneous and fragmented including much salt and pepper noise in terms of accuracy both pixel based and object based classification performs well but the former results in higher accuracies than the latter except for mapping lava flow age groups without using topographic features it is concluded that despite spectral similarity lava flows of contrasting age can be well discriminated and mapped by means of image classification the classification approach demonstrated in this study only requires easily accessible image data and can be applied to other volcanoes as well if there is sufficient information to calibrate the mapping

formation and destabilization of the high pressure assemblage garnet phengite paragonite krusne hory mountains bohemian massif the significance of the tschermak substitution in the metamorphism of pelitic rocks abstract the metamorphism of low alumina metapelites along high pressure gradients involves only a few continuous and discontinuous reactions that produce minor variations in modal mineralogy this is the case with metamorphic rocks forming the para autochthonous sequence in the vicinity of the village of m d nec krusne hory mts bohemian massif metamorphic reactions taking place among micas garnets and feldspars can be described using tschermak exchange and nak 1 exchange pressure temperature conditions for some of these continuous reactions were calculated from mineral compositions these calculations suggest that the tschermak and nak 1 exchanges are sensitive monitors of pressure and temperature conditions in these rocks the mineral assemblages of which are unsuitable for experimentally calibrated thermobarometers the results show metamorphic temperatures of 580 630 c at a pressure of 13 15 kbar during metamorphism of pre variscan basement beneath a nappe sequence

high resolution bed level changes in relation to tidal and wave forcing on a narrow fringing macrotidal flat bridging intra tidal daily and seasonal sediment dynamics abstract sediment dynamics in tidal flats ranging from daily to seasonal timescales are particularly relevant as they control key ecological and geomorphic processes that ultimately contribute to the long term evolution of coastal and estuarine landscapes yet insights into bed level changes including the full range of relevant timescales from intra tidal to daily and seasonal scales are currently limited due to a lack of efficient methods to record high resolution 1 year accordingly this contribution intends to improve our understanding on spatio temporal patterns of long term 1 year high resolution daily bed level dynamics in tidal flats in relation to the dominant hydrodynamic driving forces namely tides and waves specifically this study was conducted along two 200 m long cross shore transects on an intertidal flat located in the macrotidal 5 m tidal range scheldt estuary belgium results showed that daily bed level changes at the low tidal flat i e 4 10 m below mean high tide level were dominated by tidal currents with a strong fortnightly or spring neap signature whereas wave activity was of secondary importance conversely bed level changes in the high tidal flat i e 0 65 m below mean high tide level were almost exclusively dominated by wave activity additionally seasonal deposition erosion cycles that superimposed on the daily bed level changes were associated with the seasonality of wind wave activity and benthic biology analysis of wave and current induced bed shear stresses at the respective locations confirmed this spatial variability of tidal dominated sediment dynamics at the low tidal flat versus wave dominance at the high tidal flat and comparison with local critical bed shear stresses for sediment motion also revealed differences in morphological impacts of the hydrodynamics between the two transects these distinctive responses of bed level dynamics across the tidal flat can be partly explained by the spatially varying sediment properties across the tidal flat and may be further mediated on a seasonal time scale by the growth of the algal mat with its effect on stabilizing the sediment bed in view of the large spatial and temporal variability of internal and external forcing revealed in this study comprehensive and detailed field measurements are even more necessary to understand and predict long term bed level dynamics and related ecological implications in tidal flats

detecting and mapping buried buildings with ground penetrating radar at an ancient village in northwestern argentina abstract we describe an archaeo geophysical investigation performed near the palo blanco archaeological site catamarca argentina a large area beyond the northern limit of the site was explored with the ground penetrating radar gpr method in order to detect new buildings the exploration showed signals of mud walls in a sector that was located relatively far from the previously known buildings a detailed survey was performed in this sector and the results showed that the walls belonged to a large dwelling with several rooms the discovery of this dwelling has considerably extended the size of the site showing that the dwellings occupied at least twice the originally assumed area high density gpr surveys were acquired at different parts of the discovered building in order to resolve complex structures interpreted maps of the building were obtained different characteristics of the walls were satisfactory determined in spite of the low contrast of the dielectric constant at their interfaces and the noticeable spatial fluctuations of the signals due to wall collapses systematic excavations confirmed the gpr maps providing further relevant information about the characteristics of the walls and the occupational floor as well as material for radiocarbon analyses these analyses indicated that the discovered building was occupied until about ad 880 this fact extends 180 years the previously known period for the village and also for the settlements in the region formerly ad 200 to ad 700 the performed investigations moreover confirmed different architectural characteristics assumed for palo blanco related to the internal and external layouts interconnection between the rooms without intermediary courtyards seems to indicate a better use of the internal spaces and a more integrated spatial conception in palo blanco than in other villages of the region

superposition of variscan ductile shear deformation on pre variscan mantled gneiss structure catherine dome erzgebirge bohemian massif three tectonometamorphic events have been recognized in the crystalline rocks of the catherine mantled gneiss dome cd in the central erzgebirge the first tectonometamorphic event is characterized by the acquisition of a s1 s2 metamorphic foliation development of f2 isoclinal partly syn schistose folding and intrusion of early synkinematic granites p t conditions correspond to higher amphibolite facies metamorphism and culminate in anatexis a diapiric intrusion of cambro ordovician muscovite biotite porphyritic granite has verticalized the s2 foliation and is responsible for the genesis of the classical mantled gneiss dome oblate strain and orthorhombic diffuse c axis patterns are typical of the marginal parts of the dome

influence of history and environment on the sediment dynamics of intertidal flats abstract morphological trends of three distinct intertidal environments in south san francisco bay were investigated using a combination of measurement and modeling tools because of the inherent relationship between the physical environment and the sediment properties the sediment properties provide a good indicator of morphologic trends a significant finding of this study is that surface sediment erodibility increases as the energy level in the environment increases conversely subsurface sediment erodibility shows a strong relationship to the long term history of the site the combination of the measured sediment properties the history of deposition and erosion and simple modeling of the physical environment illustrate the interaction of these properties such that an understanding of intertidal flat behavior is developed

morphodynamic resilience of intertidal mudflats on a seasonal time scale intertidal mudflats are morphodynamic features present in many estuaries worldwide often located between vegetated shores and deep channels they comprise valuable ecosystems and serve to protect the hinterland by attenuating waves although mudflats are persistently present on yearly to decadal time scales little is known on their morphodynamic adaptation to short term variations in forcing such as storms spring neap tidal cycles and sediment supply this study aims to explore the morphodynamic resilience of mudflats to seasonal variations in forcing first we compare transects observed in south bay california at 3 to 6 monthly intervals second we present the results of a process based morphodynamic profile model mflat mflat is an open source matlab code that describes both cross shore and alongshore tidal hydrodynamics as well as a stationary wave model an advection diffusion equation solves sediment transport while bed level changes occur by the divergence of the sediment transport field mflat reproduces the observed south san francisco bay profile in equilibrium with significant skill short term variations in hydrodynamic forcing and sediment characteristics disturb the profile mainly at the channel shoal edge the modeled profile disturbance is consistent with observations the modeled profile is remarkably resilient since it recovers to the equilibrium profile within weeks to months the model results suggest that 3 monthly observation intervals are probably too long to discriminate processes responsible for the profile disturbance these processes may include variations in sediment supply mudflat erodibility and wave action as well as the spring neap tidal cycle

terrane character of the north east margin of the moldanubian zone the kutna hora crystalline complex bohemian massif three major allochthonous units have been distinguished on the north eastern border of the moldanubian zone which differ each from other in lithology and structural and metamorphic evolution their present day position displays significant metamorphic and structural inversion resulting from progressive nappe stacking during the variscan orogeny the uppermost gfohl unit consists of anatectic rocks containing high temperature high pressure relics i e granulites eclogites and garnet peridotites the rocks of the gfohl unit were strongly mylonized during uplift and later also extensively migmatized in the kyanite stability field the koui im nappe is built up by a sequence of fine grained leucocratic migmatites with preserved relics of a pre variscan deformation event this event was terminated by the intrusion of coarse grained porphyritic granites converted into augen orthogneisses by the variscan orogeny the lowermost micaschist zone was formed from a sequence of metapelites intercalated with diopsidic amphibolites

bed level changes on intertidal wetland in response to waves and tides a case study from the yangtze river delta short term bed level variability in tidal wetlands has important implication both for ecology and engineering in this study we combined in situ measurements with model simulations to quantify short term bed level changes on a meso macrotidal wetland in the yangtze river delta on the middle flat we observed erosion during neap to mean tides under onshore moderate to strong winds and bed recovery during subsequent spring tides when winds were both offshore and weaker suggesting that winds can overturn the neap spring cyclicity of bed level changes even on meso macrotidal mudflats the magnitude of bed level changes was smaller on both sides of the middle flat while the smallest changes occurred on the salt marsh observed bed level changes were reconstructed using a single point bed level change model which incorporates in situ measured parameters of hydrodynamics waves and currents suspended sediment concentrations and bed sediment properties we conclude that the relative importance of waves and tides in intertidal wetland erosion and accretion can vary temporally due to changes in balance between wave and tidal energies and spatially because of changes in elevation and vegetation in the cross shore profile our study also reflects the advantage of combination of in situ measurement with simulation in detecting short term variability of tidal flats

cross borehole resistivity tomography electrical resistivity tomography ert is a method for determining the electrical resistivity distribution in a volume from discrete measurements of current and voltage made within the volume or on its surface we have developed an ert algorithm that is an iterative modified least squares inversion based on a finite element forward solution of laplace s equation we report the results of tests on this algorithm designed to determine how resistance measurements made from two boreholes may be used to image the resistivity distribution between them a number of simple but geophysically significant structures are modeled these include a single isolated block anomaly two layers a thin isolated continuous layer and a vertical band the main features of most resistivity models were identifiable in the reconstructions limited data accuracy and noise were simulated and found to cause a deterioration of the image however even with measurements of only one significant figure accuracy the algorithm converg

ground penetrating radar survey of a prehistoric site in southern italy abstract in this paper we present and discuss the results of a ground penetrating radar gpr study carried out in an area of southern italy where a karst cave with prehistoric remains was found the aim of the study involved the imaging of the subsurface stratigraphy both inside and outside the cave in order to assist archaeologists in an excavation programme the survey grid comprised 18 intersecting gpr profiles problems associated with the use of the gpr within a cave environment are highlighted and the data processing sequence designed to extract useful geo archaeological signatures is described interpretation of the radar sections was controlled by the excavation of two trenches inside and outside the cave allowing detailed outlining the complex stratigraphy and the reconstruction of palaeolithic and neolithic subsurface horizons

compaction of igneous cumulates part ii compaction and the development of igneous foliations quantitative petrofabric analysis of 66 samples from olivine bearing zones iii and iv of the middle banded series of the stillwater complex montana was conducted to allow direct comparison among textural and chemical variations systematic variations in foliations with stratigraphic height are observed in both zones statistical analysis of the orientations of inequant grains was used to calculate an alignment factor af corresponding to the extent of the development of the foliation both petrofabric and petrographic evidence indicates that the foliation is best explained by compaction of the crystal pile comparison of afs with estimates of the amount of compaction based on whole rock compositions shows approximate agreement variations in mole fraction cl of interstitial apatite mimic the observed trends in the af indicating that local concentrations of fluids exsolved from interstitial liquid were important in the development of strong foliations we conclude that 1 differing amounts of co

extensional shearing deformation and kilometer scale a type folds in a cordilleran metamorphic core complex raft river mountains northwestern utah cordilleran metamorphic core complexes are characterized by ductile mylonitic deformation and regional stretching lineations in the raft river mountains a mylonitic zone and a late superimposed detachment fault separate precambrian crystalline and metasedi mentary basement rocks from an upper plate made of allochthonous paleozoic rocks which suffered a brittle extensive deformation we suggest that the mylonitic ductile deformation is the result of tertiary extensional tectonics strain analysis shows that 1 strain results from large scale progressive shearing deformation in a non coaxial regime 2 e w regional stretching lineations represent the direction of shearing and transport 3 shear criteria indicate an east directed movement 4 strain magnitude is increasing eastward 5 kilometer scale folds parallel to the lineations are interpreted as a type folds formed by eastward shearing of a previously northward dipping layering measurement of striated faults in the upper plate gives an e w direction of extension parallel to the lineations thus ductile and brittle deformations are closely related to the same regional scale extensional tectonics a model is proposed to explain the observed geometry and kinematics of the structures the mesozoic to paleocene cordilleran compressional tectonics induced an overthickening of the crust in the hinterland belt at the future emplacement of the complexes important uplift abnormal heating and granite emplacement occurred later during the collapse of the former belt the combined effects of thermal and gravitational instabilities during tertiary extensional tectonics enabled the development of a ductile shear zone localized at the precambrian basement paleozoic cover interface the brittle extension of the upper crust is displaced laterally along this flat shear zone and transformed farther east into the extended regions of the middle and lower crust

2 d and 3 d resistivity image reconstruction using crosshole data theoretical changes in the distribution of electrical potential near subsurface resistivity anomalies have been studied using two resistivity models the results suggest that the greatest response from such anomalies can be observed with buried electrodes and that the resistivity model of a volume between boreholes can be accurately reconstructed by using crosshole data the distributive properties of crosshole electrical potential data obtained by the pole pole array method have also been examined using the calculated partial derivative of the observed apparent resistivity with respect to a small cell within a given volume the results show that for optimum two dimensional 2 d and three dimensional 3 d target imaging in line data and crossline data should be combined and an area outside the zone of exploration should be included in the analysis in this paper the 2 d and 3 d resistivity images presented are reconstructed from crosshole data by the combination of two inversion algorithms the first algorithm uses the alpha center method for forward modeling and reconstructs a resistivity model by a nonlinear least squares inversion alpha centers ex press a continuously varying resistivity model and the distribution of the electrical potential from the model can be calculated quickly an initial general model is determined by the resistivity backprojection technique rbpt prior to the first inversion step the second process uses finite elements and a linear inversion algorithm to improve the resolution of the resistivity model created by the first step simple 2 d and 3 d numerical models are discussed to illustrate the inversion method used in processing data from several field studies are also presented to demonstrate the capabilities of using crosshole resistivity exploration techniques the numerical experiments show that by using the combined reconstruction algorithm thin conductive layers can be imaged with good resolution for 2 d and 3 d cases the integration of finite element computations is shown to improve the image obtained by the alpha center inversion process for 3 d applications the first field test uses horizontal galleries to evaluate complex 2 d features of a zinc mine the second field test illustrates the use of three boreholes at a dam site to investigate base rock features and define the distribution of an altered zone in three dimensions

quantitative analysis of crystal grain sizes and their distributions in 2d and 3d abstract we review methods to estimate the average crystal grain size and the crystal grain size distribution in solid rocks average grain sizes often provide the base for stress estimates or rheological calculations requiring the quantification of grain sizes in a rock s microstructure the primary data for grain size data are either 1d i e line intercept methods 2d area analysis or 3d e g computed tomography serial sectioning these data have been used for different data treatments over the years whereas several studies assume a certain probability function e g logarithm square root to calculate statistical parameters as the mean median mode or the skewness of a crystal size distribution the finally calculated average grain sizes have to be compatible between the different grain size estimation approaches in order to be properly applied for example in paleo piezometers or grain size sensitive flow laws such compatibility is tested for different data treatments using one and two dimensional measurements we propose an empirical conversion matrix for different datasets these conversion factors provide the option to make different datasets compatible with each other although the primary calculations were obtained in different ways in order to present an average grain size we propose to use the area weighted and volume weighted mean in the case of unimodal grain size distributions respectively for 2d and 3d measurements the shape of the crystal size distribution is important for studies of nucleation and growth of minerals the shape of the crystal size distribution of garnet populations is compared between different 2d and 3d measurements which are serial sectioning and computed tomography the comparison of different direct measured 3d data stereological data and direct presented 2d data show the problems of the quality of the smallest grain sizes and the overestimation of small grain sizes in stereological tools depending on the type of csd

quantifying the building blocks of igneous rocks are clustered crystal frameworks the foundation most phenocryst populations in volcanic rocks and those preserved in shallow level igneous intrusions are clustered variously referred to as clots clumps or glomerocrysts these clusters of crystals are the building blocks that accumulate to form the high porosity touching crystal frameworks from which igneous cumulates form examination of touching crystal frameworks in olivine komatiite cumulates and experimental charges and plagioclase dominant crystal populations holyoke flood basalt connecticut usa reveal complex high porosity clustered crystal arrangements olivine touching frameworks in komatiite flows are interpreted to form in hundreds of days plagioclase frameworks are calculated to have formed in less than 17 years for a crystal growth rate of 1 x 10 10 mm s to less than 3 years for a growth rate of 5 x 10 10 mm s based on crystal size distributions the origin of crystal clusters is likely to involve either or a combination of heterogeneous nucleation remobilization of cumulate mushes or crystals sticking together during settling and or flow the spatial distribution pattern of clustered crystal frameworks from both natural and experimental examples constrains fields on spatial packing diagrams that allow the identification of touching and non touching crystal populations and further improve our understanding of crystal packing arrangements and cluster size distributions

latest precambrian cadomian zircon ages nd isotopic systematics and p t evolution of granitoid orthogneisses of the erzgebirge saxony and czech republic single zircons from two orthogneiss complexes the grey gneiss and red gneiss the lowermost tectonic units in the erzgebirge were dated the grey freiberg gneiss is of igneous origin and has a 207pb 206pb emplacement age of 550 7 ma a quartz monzonite from lauenstein contains idiomorphic zircons with a mean 207pb 206pb age of 555 7 ma as well as xenocrysts ranging in age between 850 and 1910 ma red gneisses from the central erzgebirge contain complex zircon populations including numerous xenocrysts up to 2464 ma in age the youngest idiomorphic zircons in all samples yielded uniform 207pb 206pb ages between 550 9 and 554 10 ma nd isotopic data support the interpretation of crustal anatexis for the origin of both units nd t values for the grey gneisses are 7 5 and 6 0 respectively mean crustal residence ages of 1 7 1 8 ga the red gneisses have a wider range in nd t values from 7 7 to 2 8 tdm ages of 1 4 1 8 ga the zircon ages document a distinct late proterozoic phase of granitoid magmatism similar in age to granitoids in the lusatian block farther north east however palaeozoic deformation as well as medium pressure metamorphism 8 kbar 600 650 c are identical in both gneiss units and distinguish these rocks from the lusatian granitoids the grey and red gneisses were overthrust by units with abundant high pressure relicts and a contrasting p t evolution zircon xenocryst and nd model ages in the range 1000 1700 ma are similar to those in granitoid rocks of lusatia and the west sudetes and document a pre cadomian basement in parts of east central europe that chronologically has similarities with the sveconorwegian domain in the baltic shield

high temperature microstructures and rheology of deformed granite erzgebirge bohemian massif abstract three stages of granite deformation were recognized in porphyric granitoids sheared under amphibolite facies conditions in the erzgebirge mts 1 weakly deformed granite in lozenge shaped pods 2 s c orthogneiss and 3 thin zones of banded mylonites weakly deformed granite forms a load bearing framework lbf structure in which quartz and feldspar aggregates exhibit similar strain intensities and shapes k feldspar deforms by fracturing and onset of dynamic recrystallization along clast margins plagioclase recrystallizes completely and quartz shows effects of grain boundary migration recrystallization and activity of basal a slip s c orthogneiss is interpreted as an interconnected weak layer iwl structure with high viscosity contrast between quartz and both feldspars concentration of deformation into thin quartz layers is indicated by intense strain of quartz grain size variations of recrystallized quartz and dominant prism a slip feldspars show well annealed structures and slip on 010 001 banded mylonite is marked by similar strain intensity of quartz and feldspar aggregates and low viscosity contrast between constituent phases quartz shows evidence for grain size increase and rhomb a c slip fully recrystallized feldspars show evidence for 010 100 slip the whole microstructural sequence and the transitions from lbf structure to iwl structures show the dependence of microstructural evolution of different materials on the bulk strain intensity

the himalayan main central thrust pile and its quartz rich tectonites in central nepal as a consequence of the india asia collision a deeply rooted crustal slice has been moved southwards over the northern boundary of the indian plate at the present level of observation the main central thrust pile a rock pile of several kilometers thickness is affected by shear deformation which imprinted a flat foliation and a constant n s trending lineation these tectonites were deformed under a wide range of metamorphic conditions grading from lower greenschists up to the sillimanite field the m c t shear zone is studied from the view point of the quartz rich rocks over 100 samples helped to define a microstructural zonation roughly parallel to the thermal one 35 samples particularly rich in quartz have been used for the preferred orientation study of their c axes and a few of them for their a axes strong lattice orientations when undisturbed by mainly secondary recrystallization attest to large plastic strains in quartz the c axes are mostly distributed along unequally populated crossed girdles which may evolve into an inclined single girdle the a axes concentrate perpendicular to the more populated girdle concerning quartz the following is suggested 1 1 the deformation has a dominant shear component responsible for the dominant stretching lineation it could be simple shear in case of inclined single girdles 2 2 one set of a axes line up parallel to the shear direction slip on various planes in the a direction may be an important deformation mechanism 3 3 asymmetry in the lattice preferred orientations could be used to predict the sense of shear for the himalayan thrusting in more than 80 of cases

integrated near surface geophysical survey of the cathedral of mallorca abstract this paper describes an integrated near surface geophysical study carried out in order to obtain high resolution images of the shallow subsurface under and around the cathedral of mallorca the study was a part of a global project focused on determining the state of the building structure and on evaluating the cathedral s dynamical behaviour natural frequencies and vibration modes ground penetrating radar gpr and the capacitively coupled resistivity method were used to obtain 2d images of the shallow subsurface refraction microtremor array measurements remi were also used to characterize the rock and soil properties and several invasive boreholes provided detailed and exact information on the stratigraphy the information from the geophysical data was used to determine a final model of the ground with indications of the most likely vulnerable zones as a part of this final model gpr profiles enabled us to delineate the superficial ground structure and to detect some archaeological features electrical resistivity imaging data were in good agreement with the gpr results and showed shallow major changes in the soil and rock under the filling materials the refraction microtremor array remi results indicate the existence of compacted soils in different areas probably corresponding to old filled zones in good correlation with gpr and resistivity profiles in the most superficial part of the ground

statistical analysis of resistivity anomalies caused by underground caves geophysical prospecting of underground caves being performed on a construction site is often still a challenging procedure estimation of a likelihood level of an anomaly found is frequently a mandatory requirement of a project principal due to necessity of risk safety assessment however the methodology of such estimation is not hitherto developed aiming to put forward such a methodology the present study being performed as a part of an underground caves mapping prior to the land development on the site area consisted of application of electrical resistivity tomography ert together with statistical analysis utilized for the likelihood assessment of underground anomalies located the methodology was first verified via a synthetic modeling technique and applied to the in situ collected ert data and then crossed referenced with intrusive investigations excavation and drilling for the data verification the drilling excavation results showed that the proper discovering of underground caves can be done if anomaly probability level is not lower than 90 such a probability value was shown to be consistent with the modeling results more than 30 underground cavities were discovered on the site utilizing the methodology

on the use of changes in dihedral angle to decode late stage textural evolution in cumulates the melt filled pore structure in the final stages of solidification of cumulates must lie somewhere between the two end members of impingement in which pore topology is controlled entirely by the juxtaposition of growth faces of adjacent grains and textural equilibrium in which pore topology is controlled by the minimization of internal energies the exact position between these two end members is controlled by the relative rates of crystal growth and textural equilibration for samples in which growth has stopped or is very slow textural equilibrium will prevail a close examination of dihedral angles in natural examples demonstrates that these two end member textures can be distinguished the impingement end member results in a population of apparent solid melt dihedral angles with a median of 60 and a standard deviation of 25 30 whereas the texturally equilibrated end member population has a median of 28 and a standard deviation of 14 for the specific case of cumulates in the rum layered intrusion residual porosity in troctolitic cumulates was close to the impingement end member whereas that in peridotites was close to melt bearing textural equilibrium suites of glass bearing samples from small or frequently disturbed magma systems show modification of initial impingement textures these modifications may be a consequence of textural equilibration or of diffusion limited growth during quenching distinction can be made between these two processes by a consideration of grain shape the geometry of interstitial phases in suites of fully solidified cumulates from the rum layered intrusion shows variable approach to sub solidus textural equilibrium from an initial state inherited by pseudmorphing of the last melt textural equilibration at pore corners occurs as a continuous process with a gradual movement of the entire dihedral angle population towards the equilibrium final state if the initial pseudomorphed state is one of disequilibrium i e a melt present impingement texture this change is accompanied by a reduction in the spread of the population if it is one of equilibrium the change is accompanied by an initial increase in the spread of the population followed by a decrease these observations demonstrate that previously published models of dihedral angle change involving the instantaneous establishment of the equilibrium angle in the immediate vicinity of the pore corner are incorrect

cross shore hydrodynamics within an unsaturated surf zone abstract this paper concerns the hydrodynamics induced by random waves incident on a steep beach new experimental results are presented on surface elevation and kinematic probability density functions cross shore variation in wave heights the fraction of broken waves and velocity moments the surf zone is found to be unsaturated at incident wave frequencies with a significant proportion of the incident wave energy remaining at the shoreline in the form of bores wave heights in both the outer and inner surf zones are best described by a full rayleigh distribution thornton e b guza r t 1983 transformation of wave height distribution j geophys res 88 5925 5938 rather than a truncated rayleigh distribution as used by battjes and janssen 1978 battjes j a janssen j p 1978 energy loss and setup due to breaking of random waves proc 16th int conf coastal eng asce new york pp 569 588 a new parametric wave transformation model is outlined which provides explicit expressions for the fraction of broken waves and the energy dissipation rate within the surf zone on steep beaches the model appears to offer improved predictive capabilities over the original battjes and janssen model cross shore variations in the velocity variance and velocity moments are best described using linear gaussian wave theory with less than 20 of the velocity variance in the inner surf zone due to low frequency energy

peridotite sills and metasomatic gabbros in the eastern layered series of the rhum complex mapping of the eastern layered series els of the rhum ultrabasic complex on the northern flank of hallival shows that peridotite and allivalite troctolite or gabbro layers are laterally discontinuous and vary both in thickness and lithology peridotite generally has sharp upper and lower contacts against the allivalites which sometimes cut across the layering in the allivalite reaction dissolution and hybridization effects between peridotite and allivalite are developed locally some troctolite layers terminate as isolated fingered blocks in peridotite there are many small peridotite bodies which are clearly intrusive into allivalite and have previously been identified as distinct peridotite sheets and plugs they are petrographically almost identical to the major stratiform peridotites and in some cases are apophyses from them we propose that many of the peridotite layers in the els formed as thick sills of picritic magma emplaced into a partly solidified layered troctolite complex the stratiform gabbros of the els are heterogeneous layered rocks that commonly contain relicts of troctolite and anorthosite wavy metre scale contacts between gabbro and troctolite cut across pre existing grain size modal and rhythmic layering with little disruption these metasomatic gabbros mimic the textures grain size and rhythmic layering of their troctolitic protoliths we propose that many of the els gabbros formed as a result of interaction between porous troctolites and a low temperature basaltic melt residual basaltic melt segregated from solidifying peridotite may have caused this metasomatism

rapid 1d 3d inversion of shallow resistivity multipole data examples in archaeological prospection fifteen years ago the introduction of mobile multipole arrays led to substantial improvements in shallow electric prospection because it allowed information related to thevertical distribution of ground resistivity in complement to the horizontal pattern of the detected features to be extracted however to make full use of this wealth of information further progress is needed to extendthequalitativeinterpretationofdatatoamorequantitative evaluation of the explored terrain to that intent we developed a two step process in the first step a 1d electric model is fitted to the data over the full explored area and in the second step using the moment method localized 3d interpretation is applied to limited areas for which the characteristics of a given feature require closer scrutiny after a first test with synthetic data generated using the surface integral 3d modeling method this process was applied to three different archaeological sites and one test site for both handheld pole pole array systems and a multipole continuous electric profiling mechanically pulled system at the test site the characteristics of a known wall were accurately recovered at the duntzenheim site the thickness and width of the archaeological remains determined by 3d interpretation corresponded to the features observedthrough excavation at the other two sites 3d interpretation made it possible to establish that the conductive features extend across the full extent of the superficial resistive second layers

contribution of the resistivity method to characterize mud walls in a very dry region and comparison with gpr abstract mud walls are frequent in many archaeological sites including sites located in semi desert regions in cases with buried walls the geophysical methods can be useful tools for their investigation since they provide maps of the subsoil in a non invasive way and in relatively short times this article deals with the characterization of mud walls in very dry soils through the resistivity method discussing a methodology to satisfactorily apply the method in this kind of adverse environment and how to interpret the results the case of the palo blanco archaeological site a pre incaic village located in the nw region of argentina is analyzed in very dry soils it is frequent that the electrical current cannot be injected due to the high values of electrical resistivity at the shallowest portions of soil which makes the resistivity method useless here we show how this problem can be systematically overcome by wetting a shallow thread between each pair of injection electrodes and the manner in which the resulting profiles can be analyzed we perform numerical simulations of the resistivity profiles considering 3d models of mud walls and wetted threads that reproduce experimental situations and compare them to 2d field data the resistivity profiles are analyzed for different orientations and distances between the wall and profile and fluctuations of the soil parameters the experimental profiles are interpreted from these simulations and compared to ground penetrating radar gpr profiles the resistivity methodology shows effective for characterizing the size and depth of the mud walls even in cases with collapsed or much eroded walls for which gpr often fails

eclogites from the czech part of the erzgebirge multi stage metamorphic and structural evolution a structural and petrological study of saxothuringian eclogites in the central erzgebirge czech republic revealed their polyphase thermal and tectonic evolution the first stage of deformation is related to eclogite facies metamorphism of mafic rocks at pressures of 26 kbar and temperatures of 650 700 c the clinopyroxene crystallographic preferred orientation is consistent with high temperature flow the second stage of deformation is characterized by transport of eclogitic rocks at the base of a crustal nappe and their large scale folding during this stage hp ht metamorphic assemblages developed in the surrounding metapelites 14 5 kbar 600 c while eclogite assemblages were preserved in passively transported eclogitic boudins heat advection and similar p t conditions in the surrounding crustal material are responsible for the stability of mineral assemblages and preclude closure of isotopic systems in the eclogites therefore the published isotopic ages of the eclogites do not reflect the subduction stage but the age of cooling under crustal conditions subsequent large scale d3 folding is responsible for reorientation of previously flat lying earlier fabrics d1 d2 the final stage of deformation is marked by the development of a heterogeneous network of ductile retrograde shear zones the thermometry and geochemical study of amphibolitized eclogites in the cores of shear zones indicates thermal conditions not exceeding those in surrounding metapelites and fluid influx the fluid influx is interpreted to be the result of water producing prograde reactions in the footwall metasediments and fluid chanelling into the base of the nappe during brittle deformation of the eclogites