pressure solution deformation of the purgatory conglomerate from rhode island pressure solution is the dominant mechanism for the alleghenian age deformation of pennsylvanian quartzite conglomerates from the narragansett basin rhode island this deformation is accompanied by inter cobble rotation and occurred at low metamorphic grades no microscopic evidence for internal penetrative deformation of cobbles in the conglomerate is observed three major pressure solution features are characteristic of this conglomerate adjacent cobbles show indentation relationships with no change in quartz fabrics within the individual cobbles insoluble material is concentrated between cobbles in mutual contact both in the matrix and within the outer margins of the cobbles quartz overgrowths are found at the long axis terminations of the cobbles many other pressure solution features are discussed these features remain recognizable after subsequent metamorphism review of other studies suggests that pressure solution may well be a common conglomerate deformation mechanism during early deformati

state of strain in a quartzite mylonite central australia abstract the finite strain due to mylonitization of a quartzite has been determined using measurements of deformed quartz grains and ribbons developed from quartz grains equant before the deformation the mylonites are developed in long narrow steeply dipping mylonite zones within the chewings range quartzite of central australia this quartzite is very pure 98 quartz the quartzite surrounding the mylonite zones appears unstrained the samples examined exhibit severe flattening strains k values of between 0 01 and 0 12 and r values of between 5 and 30 have been determined application of formulae to calculate volume change assuming the model of an ideal ductile deformation band structure indicate significant apparent volume losses with values between 0 69 and 0 95 such values seem unreasonably high as no geological evidence for large volume loss is seen the band structure model is considered inapplicable for these mylonite zones the observed structural features can best be explained by a deformation history involving severe bulk shortening normal to the zones

calculation of volume change in ductile band structures abstract volume changes incurred during the development of ideal band structures infinite shear zones can be readily calculated if one knows the principal directions and principal ratios of total strain within and adjacent to the ideal band structures the calculation is greatly simplified if one knows the directions and ratios of the strain that generated the band structures or if the total strain of the host rocks is zero in some natural deformation zones apparent volume losses according to the band model exceed 30 and may be unreasonably high further determinations of apparent volume change will help to judge the physical viability of the band model and its strict geometrical requirements for example the propagation of embryonic deformation zones may lead to total strain patterns that differ greatly from those of band structures

chemical and physical responses to deformation in micaceous quartzites from the tauern window eastern alps micaceous quartzites from a subvertical shear zone in the tauern window contain abundant quartz clasts derived from dismembered quartz tourmaline veins bulk plane strain deformation affected these rocks at amphibolite facies conditions shape changes suggest net shortening of the clasts by 11 64 with a mean value of 35 quartz within the clasts accommodated this strain largely via dislocation creep processes on the high stress flanks of the clasts however quartz was removed via solution mass transfer pressure solution processes the resulting change in bulk composition allowed growth of porphyro blastic staurolite chlorite kyanite on the clast flanks matrix sio2 contents decrease from c 83 wt away from the clasts to 49 58 in the selvages on the clast flanks the chemical changes are consistent with c 70 volume loss in the high stress zones calculated shortening values within the clast flanks are similar to the volume loss estimates and are greatly in excess of the shortening values calculated from the clasts themselves flow laws for dislocation creep versus pressure solution imply large strain rate gradients and or differential stress gradients between the matrix and the clast selvages in a rock containing a large proportion of semirigid clasts weakening within the clast flanks could dominate rock rheology in our samples however weakening within the selvages was self limiting 1 growth of strong staurolite porphyroblasts in the selvages protected remaining quartz from dissolution and 2 overall flattening of the quartz clasts probably decreased the resolved shear stress on the flanks to values near those of the matrix which would have reduced the driving force for solution transfer creep extreme chemical changes nonetheless occurred over short distances the necessity of maintaining strain compatibility may lead to significant localized dissolution in rocks containing rheologic heterogeneities and overall weakening of the rocks may result solution transfer creep may be a major process whereby weakening and strain localization occur during deep crustal metamorphism of polymineralic rocks

assessment of solute fluxes beneath an orchard irrigated with treated sewage water a numerical study 1 detailed numerical simulations were used to analyze water flow and transport of nitrate chloride and a tracer solute in a 3 d spatially heterogeneous variably saturated soil originating from a citrus orchard irrigated with treated sewage water tsw considering realistic features of the soil water plant atmosphere system results of this study suggest that under long term irrigation with tsw because of nitrate uptake by the tree roots and nitrogen transformations the vadose zone may provide more capacity for the attenuation of the nitrate load in the groundwater than for the chloride load in the groundwater results of the 3 d simulations were used to assess their counterparts based on a simplified deterministic 1 d vertical simulation and on limited soil monitoring results of the analyses suggest that the information that may be gained from a single sampling point located close to the area active in water uptake by the tree roots or from the results of the 1 d simulation is insufficient for a quantitative description of the response of the complicated 3 d flow system both might considerably underestimate the movement and spreading of a pulse of a tracer solute and also the groundwater contamination hazard posed by nitrate and particularly by chloride moving through the vadose zone this stems mainly from the rain that drove water through the flow system away from the rooted area and could not be represented by the 1 d model or by the single sampling point it was shown however that an additional sampling point located outside the area active in water uptake may substantially improve the quantitative description of the response of the complicated 3 d flow system

numerical analyses of subsurface flow in a steep hillslope under rainfall the role of the spatial heterogeneity of the formation hydraulic properties 1 the paper aims at analyzing subsurface flow and streamflow generation in steep hillslopes after rainfall the principal scope of the work is to assess the role played by the spatial variability of the hydraulic properties on the subsurface flow patterns and hillslope discharge we try to address this task through a three dimensional numerical model which solves the richards equation under prescribed initial and boundary conditions along an established practice the relevant hydraulic parameters are modeled as random space functions with given statistical properties realistic features of the spatially variable formation parameters and the precipitation data are incorporated into the simulation model it is found that spatial heterogeneity has a significant impact on the movement of water in the hillslope and the streamflow generation in particular the heterogeneous systems are more sensitive to rain input and display an increase of both the water table and saturation which is faster than the homogeneous case the same is for water velocity which is everywhere larger when heterogeneity is considered as a consequence the dynamics of subsurface stormflow recognized as the leading mechanism for streamflow generation in the simulations and the outflow discharge produced by the hillslope after a rain event are enhanced by heterogeneity despite of the possible lack of generality of the numerical experiments they provide useful insight into the complex dynamics occurring in hillslope systems the simulations show the importance of including realistic spatial heterogeneity in hillslope hydrology studies

the new england batholith constraints on its derivation from nd and sr isotopic studies of granitoids and country rocks abstract nd and sr isotopic compositions are reported for the granitic suites which comprise the late palaeozoic to earliest mesozoic new england batholith of eastern australia some of the granitic suites are typically i type in their mineralogy chemistry and isotopic compositions implying a derivation from igneous infracrustal source rocks whereas other suites have characteristics consistent with a derivation from a protolith which was predominantly sedimentary and relatively felsic s types the i type granitoids of the nundle suite have nd values 3 3 to 6 1 that are amongst the most primitive yet documented for a relatively felsic sio 2 65 plutonic suite and these values imply a derivation from either a depleted upper mantle source or more probably a complex source region involving both volcanic arc rocks and detrital material their compositions are distinctly more primitive than those of the new england super suite which constitutes the permian core of the batholith this extensive super suite comprising granitoids traditionally designated as i type has an overall range in initial nd and sr isotopic compositions of 1 7 to 4 6 and 0 70458 to 0 70624 respectively although the majority of plutons have initial nd isotopic compositions which fall into a very narrow range 1 0 1 5 units this limited range is remarkable considering the extreme lithological diversity and range in chemical composition of the analysed samples sio 2 47 74 and implies a source region of considerable volume having reasonably uniform isotopic compositions but variation in chemistry a similarly uniform source isotopically is also indicated for the s type granitoids of the carboniferous hillgrove suite and carboniferous permian bundarra suite with initial nd values of 0 8 to 2 3 and initial 87 sr 86 sr compositions of 0 70474 to 0 70577 showing only limited ranges five pelites three felsic and four mafic greywackes representing typical country rocks from different stratigraphic levels have initial nd values 1 7 to 6 6 and initial 87 sr 86 sr compositions 0 70378 to 0 70585 which essentially mirror the compositional variation in the granitoids a chemical mineralogical and isotopic bimodality in these sediments indicates two very distinctive sources one felsic rhyodacitic the other relatively mafic andesitic which were separated spatially and temporally in many but not all areas of early to mid palaeozoic new england a model is presented in which the s type granitoids are derived from a predominantly felsic source i e pelites and felsic greywackes whereas some of the granitoids belonging to the new england super suite may have been derived from source rocks consisting of both felsic and mafic sedimentary components the distinction between many s type and i type granitoids in new england is unclear for two principal reasons a because the granitoids and their respective source rocks are relatively young geologically so that their isotopic systems have not evolved to any considerable extent and b because of the intrinsic igneous chemical compositions of any sedimentary component that may be involved in their genesis

kinematic history of the narragansett basin massachusetts and rhode island constraints on late paleozoic plate reconstructions the formation of the narragansett basin of rhode island and massachusetts and the polyphase deformation geometry of the pennsylvanian age basin sediments can be explained by collision and strike slip interactions between an avalonian microcontinent the european north american plate and the african plate during the late paleozoic sinistral movement between an avalonian microcontinent and the european north american plate resulted in formation of pull apart basins subsequently africa moved toward north america along an east west trending dextral megashear zone and collided with the eastern margin of southern north america the narragansett basin is located on the avalonian microcontinent near the suture with the north american continent and in the transition zone between the megashear and the collision tectonic regimes the basin shape stratigraphy and sedimentary relationships can be explained by the coalescence of two composite grabens which formed at different times the thicker northern graben is only affected by one deformation whereas the southern graben shows evidence of four distinct phases of postrifting deformation the first two coaxial folding deformations of the basin sediments are attributed to the closure of the basin complex during collision of africa and north america the third and fourth deformations are interpreted as sinistral r riedal and dextral shears respectively associated with the east west trending megashear system a prograde barrovian metamorphic front started in the western portion of the southern graben slightly after the first deformation and migrated northward and eastward where it is synchronous with the second deformation

solute transport through a heterogeneous coupled vadose saturated zone system with temporally random rainfall the transport of nonreactive solutes through a coupled two dimensional randomly heterogeneous vadose saturated zone system subject to temporally random rainfall is predicted by monte carlo simulation and compared with previously published analytic results for three different rainfall patterns the relative contributions of the uncertain inputs i e rainfall and saturated conductivity to the prediction uncertainty of solute transport are quantified in terms of the statistical moments of the pore water velocity the plume spatial moments and solute flux breakthrough curves at downstream control planes results show that the mean and variance of the saturated zone pore water velocity were approximately equivalent for the cases of uniform and random rainfall and were well predicted by the analytical relationships developed by rubin and bellin 1994 as a result the mean plume displacement estimated by the trajectory of the mean plume center of mass was found to be nearly identical for these cases in the temporally random rainfall case the saturated zone mean plume experienced more spread in the direction of mean flow at early times however the asymptotic rates of spatial spreading of the mean solute plumes were found to be approximately equivalent for the uniform and random rainfall cases and well predicted by the approximate expressions for longitudinal macrodispersivity in nonuniform flow proposed by destouni and graham 1995 random rainfall and random soil properties increased prediction uncertainty of the solute plume behavior in the vadose zone by an order of magnitude when compared with the uniform rain and random soil case this effect was reduced considerably when the solute entered the saturated zone where random rainfall produced only slightly larger prediction uncertainty than the uniform rainfall case the analytic model developed by destouni and graham 1995 accurately predicted the temporal breakthrough of the mean solute plume at saturated zone control planes for all cases if transport through the unsaturated zone accounted for the effects of temporally random rainfall using the methodology developed by foussereau et al 2000a 2000b results of this work indicate that for the humid climates studied here uncertain rainfall patterns dominate transport prediction uncertainty in the shallow unsaturated zone while uncertain solute breakthrough to the saturated zone and uncertain hydraulic conductivity dominate prediction uncertainty in the saturated zone

amphibolites and related rocks from the wongwibinda metamorphic complex northern n s w australia amphibolite bands and lenses in pelitic and psammitic schists of the wongwibinda metamorphic complex northern new south wales display a variety of assemblages including hornblende plagioclase hornblende plagioclase diopside hornblende plagioclase cummingtonite cummingtonite plagioclase hornblende biotite anthophyllite cordierite plagioclase biotite and hornblende spinel olivine orthopyroxene chlorite field relations chemical variation trends and occasional relict textures indicate these rocks were derived from basaltic lavas their intimate association with metacherts suggests submarine extrusion unsystematic chemical and mineralogical small scale variation within the amphibolites is attributed to chemical redistribution associated with low temperature hydrothermal alteration of the volcanics prior to high grade regional metamorphism at 650 700 c and 2 4 kb the diopside cummingtonite and anthophyllite bearing lithologies are believed to be the main products of this redistribution the hornblende plagioclase and hornblende spinel olivine orthopyroxene chlorite rocks probably most closely approach the primary chemical compositions of the original lavas believed to be basalts and picrite basalts chemically similar to ocean floor tholeiites

40ar 39ar ages from the narragansett basin and southern rhode island basement terrane their bearing on the extent and timing of alleghenian tectonothermal events in new england pennsylvanian sedimentary rocks record the effects of progressive barrovian metamorphism and polydeformation in the narragansett basin of rhode island whole rock phyllite samples from low grade portions of this terrane display internally concordant 40 ar 39 ar age spectra with plateau ages of 248 to 258 m y four samples biotite from higher grade rocks records plateau ages of 240 to 248 m y eight samples similar 40 ar 39 ar biotite ages are displayed westward across the southern rhode island basement terrane 239 to 250 m y nine samples although coexisting hornblende records slightly older plateau ages of 255 m y two samples the 40 ar 39 ar plateau ages are interpreted to date times of post metamorphic cooling through temperatures required for argon retention in the various mineral phases examined the ages suggest that a distinct late paleozoic alleghenian thermal event affected much of southern rhode island together with the depositional ages of the variably metamorphosed pennsylvanian rocks westphalian b stephanian a or b the 40 ar 39 ar data permit calibration of the sequence of alleghenian tectonothermal events recorded in the narragansett basin the controls suggest a permian event lasting about 40 to 50 m y between initial barrovian regional metamorphism and synchronous d 1 d 2 ductile deformation between 295 and 275 m y and post d 3 cooling below argon retention temperatures between 250 and 240 m y

longitudinal and lateral dispersion in an unsaturated field soil lateral and longitudinal dispersion was quantified in a field soil under water unsaturated conditions the relatively mobile dye tracer brilliant blue fcf was applied as a line source and leached into the soil at two different rates of infiltration 4 and 24 mm d 1 respectively the resulting tracer plume was photographically recorded at vertical soil profiles excavated perpendicularly to the line source after 50 100 and 200 mm of cumulative infiltration an image analysis technique was used to determine two dimensional concentration distributions from the photographs average horizontal and vertical concentration distributions were analyzed using the two dimensional advection dispersipn equation model parameters were fitted to optimize the agreement between measured and modeled averaged concentration profiles in both horizontal as well as vertical directions dispersivities showed a dependency on flow rates and amount of cumulative infiltration but this dependency appeared to be related to the degree of irregularities of observed flow patterns large dispersivities were associated with higher degree of irregularities in the flow patterns and vice versa layer boundaries played a significant role for redirecting flow when flow rates were high and cumulative infiltration was large this study demonstrates 1 that more than just the vertical concentration profiles are needed to define the transport regime under unsaturated conditions and 2 that even subtle layer boundaries affect the lateral mixing regime and exert a marked influence on the transport in the main flow direction

pressure solution deformation of the purgatory conglomerate rhode island u s a quantification of volume change real strains and sedimentary shape factor abstract pressure solution has caused substantial volume redistribution within the purgatory conglomerate from rhode island material has been removed from quartzite cobble surfaces parallel to the fold axes and mostly redeposited as fibrous pressure shadows at the long axis terminations of the cobbles in the hinges of folds 23 of the mean cobble volume has been removed and in highly deformed and overturned fold limbs up to 55 volume reduction has occurred the initial cobble shape and orientation can be measured at an undeformed locality and the deformation path can be easily deduced thus these are real cobble volume reductions apparent volume losses initial shapes not removed range from 70 to 89 real strains for cobbles axial ratios ranging from 1 0 65 0 38 to 1 0 47 0 15 have values of e x e y e z which range from 0 20 11 to 0 37 42 respectively depending on structural position the conglomerate itself has been extended parallel to the fold axes e r but the extension is not recorded by the cobble shapes

rheology of a coaxial shear zone in the virginia blue ridge wet quartzite dislocation creep at 250 280 c abstract cambrian quartzite along the western margin of the blue ridge near front royal virginia records significant penetrative strain under subgreenschist facies conditions strain analyses of the quartzite indicate general flattening and octahedral shear strain values up to 1 25 x z up to 5 7 1 samples with x z as low as 1 5 1 have crystallographic preferred orientations that record a dominance of basal slip and patterns consistent with coaxial flattening in most samples quartz has undergone minor amounts of dynamic recrystallization with mean grain sizes 4 5 m locally the quartzite is brittlely deformed and subgrains and recrystallized bulges are present along fractures and extinction bands fluid inclusion planes and fluid inclusions along deformation lamellae are abundant and quartz ftir analyses yield average h 106si values of 1100 3300 indicating fluid flow and high intragranular water content during deformation higher strain samples generally record lower water contents which may indicate that fluids migrated to grain boundaries during deformation dissolution microstructures are rare in high strain samples and we interpret most strain to have been accommodated by dislocation creep thermal modeling of zircon low temperature thermochronology data coupled with quartz c axis opening angle thermometry suggest deformation temperatures were likely 250 280 c these deformation temperatures are lower than what is typically considered the brittle plastic transition in quartz we attribute localization of this high strain zone and dislocation creep at these temperatures to hydrolytic weakening and a relatively low strain rate estimated to be 10 15 s 1

stochastic analysis of simulated vadose zone solute transport in a vertical cross section of heterogeneous soil during nonsteady water flow the problem of transport of a conservative nonreactive solute in a vertical cross section of a hypothetical partially saturated scale heterogeneous soil under transient water flow was analyzed here it was assumed that locally the water flow and the solute transport can be described by the richards equation and by the one component convection dispersion equation respectively the simulated water content and the solute concentration distributions in the vertical cross section of the soil at different elapsed times were quantified in terms of space averages and two point autocorrelation functions the time evolution of the solute plume was quantified in terms of its first two normalized spatial moments from which the time dependence of the longitudinal and the transverse components of the solute velocity vector and the spatial covariance tensor were estimated the results of this study which are relevant to solute transport at the local or the plume scale demonstrated the considerable variability in the solute concentration in space and time due to the complex heterogeneity of the soil hydraulic properties in both the vertical and the horizontal directions consequently the movement of the solute plume was characterized by a compression expansion phenomenon attributed to the decrease in the effective solute velocity through the zones of relatively fine textured soil material it was concluded that existing stochastic vadose zone transport models may be applicable to shallow depths but may fail to describe the actual spread of a solute plume when the transport takes place at relatively large depths mainly because of the neglect of the significant vertical heterogeneity in the soil hydraulic properties

power law catchment scale recessions arising from heterogeneous linear small scale dynamics 1 power law recession behavior has typically been attributed to the hydraulics of subsurface flows in the landscape e g the boussinesq equation many catchments exhibit enormous heterogeneity in their characteristics such as the permeability of soils hillslope length and gradient and soil mantle thickness in the paper we demonstrate using a simple linear flow model that the between hillslope heterogeneity alone can give rise to observed apparently nonlinear recession slope curves the degree of nonlinearity represented by the exponent fitted to the recession slope curve is shown to increase with the degree of heterogeneity of catchment hydraulic properties in sufficiently heterogeneous catchments the recession is also sensitive to the history of recharge events tending to increase when the past events have built up a storage of water in the slow parts of the catchment the models based on the catchment heterogeneity were fitted to data from the panola mountain research watershed yielding a good fit and allowing us to infer how the heterogeneity in catchment properties varies with scale the range of exponents explained by this theory overlaps with the range explained by the hydraulics of subsurface flow which raises doubts about our ability to extract catchment hydraulic parameters on the basis of recession curves so long as the heterogeneity is not accounted for in general the results presented here have enabled us to show how the heterogeneity of landscape characteristics is upscaled and manifested in the apparent nonlinear relationship at the catchment scale

hydrologic response of catchments to precipitation quantification of mechanical carriers and origins of water 1 precipitation induced overland and groundwater flow and mixing processes are quantified to analyze the temporal event and pre event water and spatial groundwater discharge and overland runoff origins of water entering a stream using a distributed parameter control volume finite element simulator that can simultaneously solve the fully coupled partial differential equations describing 2 d manning and 3 d darcian flow and advective dispersive transport mechanical flow driven by hydraulic potential and tracer based hydrograph separation driven by dispersive mixing as well as mechanical flow are simulated in response to precipitation events in two cross sections oriented parallel and perpendicular to a stream the results indicate that as precipitation becomes more intense the subsurface mechanical flow contributions tend to become less significant relative to the total pre event stream discharge hydrodynamic mixing can play an important role in enhancing pre event tracer signals in the stream this implies that temporally tagged chemical signals introduced into surface subsurface flow systems from precipitation may not be strong enough to detect the changes in the subsurface flow system it is concluded that diffusive dispersive mixing capillary fringe groundwater ridging and macropore flow can influence the temporal sources of water in the stream but any sole mechanism may not fully explain the strong pre event water discharge further investigations of the influence of heterogeneity residence time geomorphology and root zone processes are required to confirm the conclusions of this study

effect of pulse release date and soil characteristics on solute transport in a combined vadose zone groundwater flow system insights from numerical simulations 1 the transport of a conservative tracer bromide in a three dimensional heterogeneous combined vadose zone groundwater flow system was analyzed through a series of detailed numerical simulations the scope of the present study was to analyze the effect of both the soil type and the pulse application date on solute movement and spreading in the combined flow system subject to time dependent external forcing conditions f t characterized by a time period imposed on a flat soil surface of particular interest were the suitability of the time invariance assumption of the solute travel time distribution and the related issue of the capability of an equivalent steady state vadose zone flow model to describe solute transport in a realistic flow system considering flow systems in which the water table is located at sufficiently large distance from the flat soil surface the main results of this study suggest that the velocity associated with the wetting front position which may be considered as an effective velocity is soil and calendar date dependent consequently characteristics of the transport i e solute displacement and spreading first and peak arrival times are soil and pulse release date dependent the soil dependent solute travel time pdf at a cp located in the vicinity of the water table however may be considered as essentially independent of the pulse release date particularly in the fine textured clay soil associated with mean travel time that substantially exceeds furthermore for the equivalent steady state definition of the flow problem may be quite effective in describing the solute travel time pdf of the actual transport process occurring under nonmonotonous transient flow conditions

unraveling the geometry of the new england oroclines eastern australia constraints from magnetic fabrics the southern new england orogen neo in eastern australia is characterized by tight curvatures oroclines but the exact geometry of the oroclines and their kinematic evolution are controversial here we present new data on the anisotropy of magnetic susceptibility ams which provide a petrofabric proxy for the finite strain associated with the oroclines we focus on a series of preoroclinal devonian carboniferous fore arc basin rocks which are aligned parallel to the oroclinal structure and by examining structural domains we test whether or not the magnetic fabric is consistent with the strain axes ams data show a first order consistency with the shape of the oroclines characterized in most of structural domains by subparallelism between magnetic lineations structural axis and bedding with the exception of the gresford and west hastings domains our results are relatively consistent with the existence of the manning and nambucca hastings oroclines reconstruction of magnetic lineations to a prerotation i e pre late carboniferous stage considering available paleomagnetic results yields a consistent and rather rectilinear ne sw predeformation fore arc basin this supports the validity of ams as a strain proxy in complex orogens such as the neo in the hastings block magnetic lineations are suborthogonal to bedding possibly indicating a different deformational history with respect to the rest of the neo

petrogenesis and tectonic significance of amphibolites interlayered with metasedimentary gneisses in the ivrea zone southern alps northwest italy abstract amphibolites occurring as elongate lenses and boudins within the metasedimentary kinzigite formation of the ivrea zone are all of igneous parentage a detailed study of their trace element characteristics shows that they can be divided into two groups type 1 amphibolites occur as layers up to 100 m thick and have trace element distributions showing depletion in incompatible elements typical of normal n type mid ocean ridge basalts type 2 amphibolites occur as thinner layers and boudins and have higher levels of the more incompatible elements similar to transitional or enriched e type ocean basalts although metamorphism appears to have resulted in loss of sio 2 and variable enrichment in na k rb ba sr and locally ca the less mobile elements including the rare earth elements have preserved the primary basaltic geochemical characteristics the tectonic model which best explains the assemblage of slivers of morb like amphibolites within extremely highly deformed semi pelitic metasediments is that of an accretionary sedimentary wedge formed at a palaeozoic subduction zone

the effects of dissolution precipitation creep on quartz fabrics within the purgatory conglomerate rhode island abstract quartz crystallographic preferred orientation cpo patterns are most commonly a result of deformation by dislocation creep we investigated whether dissolution precipitation creep dpc a process that occurs at lower differential stresses and temperatures may result in cpo in quartz the purgatory conglomerate is part of the se narragansett basin where strain intensity increases from west to east and is associated with top to the west transport and folding during the alleghanian orogeny within the purgatory conglomerate dpc led to quartz dissolution along cobble surfaces perpendicular to the shortening direction and quartz precipitation in overgrowths at the ends of the cobbles strain shadows parallel to the maximum extension direction quartz c axis orientations as revealed by electron backscatter diffraction ebsd methods were random in all analyzed domains within the cobbles and strain shadows irrespective of the intensity of strain or metamorphic grade of the sample quartz dissolution probably occurred exclusively along the cobbles margins leaving the remaining grains unaffected by dpc the fact that quartz precipitated in random orientations may indicate that the strain shadows were regions of little or no differential stress

determination of pressure solution shortening in sandstones abstract a new method for the determination of pressure solution shortening in sandstones uses the geometry of grain to grain interpenetrations and grains truncated against solution surfaces these features are used to construct plots from which the magnitude and direction of the pressure solution shortening can be determined using simulated pressure solution deformation of artificial and natural grain populations the new method is shown to correctly assess a variety of coaxial and non coaxial shortenings although primarily intended to determine shortening the method can also quantify extension related to growth of beards or overgrowths during pressure solution application of the method to naturally deformed quartz arenite samples shows that pressure solution shortening of up to 26 occurred during compaction and 22 during layer parallel shortening

finite strain patterns in some alpine nappes abstract the patterns of finite strain in some alpine nappes and thrust sheets are reviewed together with their tectonic evolution glarus nappe the finite strain pattern approximately that of heterogeneous simple shear was acquired during upper oligocene times when the helvetic thrust block was deformed together with its infrastructure and basement the glarus thrust was formed during miocene times and modified by pliocene to recent differential uplift morcles nappe this large recumbent fold nappe overrode the aiguilles rouges massif and its cover towards the northwest the finite strain pattern resulted from successive diagenetic compaction multilayer buckling and heterogeneous simple shear high strains occur along the inverted limb of the nappe and fold hinges are oriented subperpendicular to the nw stretching lineation final emplacement of the nappe during the miocene was perhaps a later event chartreuse massif 33 e w shortening was developed across this fold and thrust belt during post helvetian times by decollement along the oxfordian shales in response to thrusting and uplift in the belledonne basement the oxfordian shales had earlier accommodated a pre helvetian probably oligocene deformation in the basement and its trias bajocian cover when n030 trending subhorizontal folds cleavage and a stretching lineation 18 n030 stretching were developed digne nappe detached along the keuper evaporites the cover was displaced westwards in two stages 1 late oligocene with folding cleavage development formation of the frontal slices and an overall e w shortening of 20 and 2 late miocene pliocene after emplacement of the embrunais nappes in the east producing the digne thrust it is concluded that for these alpine nappes geological criteria must be used to establish their evolution if the internal deformation can then be assigned to part of this evolution the pattern of finite strain can be used to quantify and elucidate that part a maximum of information is gained if the incremental deformation history can also be obtained from study of syntectonic fibres

estimation of volume changes by comparative chemical analyses in heterogeneously deformed rocks folds with mass transfer abstract this paper presents a method for calculating the volume change between the various sectors of the same heterogeneously deformed layer fold shear zone by comparing the chemical composition of deformed sectors with that of a reference sector the principle consists of considering some minerals as being insoluble illite chlorite and passively concentrated in deformed zones because of the loss of more soluble minerals quartz calcite dolomite by pressure solution simple observations can be used to test the validity of the assumptions required to calculate volume change in the analysis of a slaty matrix around a ptygmatic fold a map of values is drawn and these values are shown to be compatible with the general strain pattern for several limb hinge pairs of straight limbed folds the relations between volume change elongation parallel to limb layering l l o and the angle between limb and hinge are determined the influence of various parameters such as temperature pressure initial composition and structure of the rock on these relations is also pointed out

a post deformational post peak metamorphic timing for mineralization at the archaean big bell gold deposit western australia abstract previous workers were unable to find any suitable criteria to time gold mineralization at big bell mine an enigmatic low grade large tonnage deposit hosted in an upper amphibolite facies greenstone belt sequence in the murchison province of the archaean yilgarn craton western australia earlier studies suggested that the gold mineralization occurred by hydrothermal alteration either synchronous with volcanism or prior to peak metamorphism the following conclusions have been drawn from a detailed meso and microstructural analysis of the mine sequence and greenstone belt hosting the orebody 1 1 prior to mineralizaton the big bell area underwent five phases of deformation and m1 regional metamorphism to the staurolite andalusite zone of the amphibolite facies for metasediments 2 2 granite emplacement post dated d5 folding causing local m2 thermal metamorphism this peaked at the ms qtz breakdown reaction for pelites on or close to the and sil transition but below the onset of partial melting characterized by the narrow non degenerate divariant field involving seven kfmash phases qtz ms bt crd kfs als h2o this hornfelsing consumed cross cut and post dated s5 cleavage prograde qtz and sil veins replaced this hornfels assemblage and s5 cleavage and were caused by volatile escape at depth and hydraulic fracturing coincident with a reduction in bulk rock permeability resulting from post deformational hornfelsing 3 3 retrograde m3 assemblages and two stages of gold related mineralization cross cut and replaced all previous structures the retrograde gold bearing assemblages are both underformed stage 1 mineralization is typically found with widespread retrograde muscovite plates and consists of the following mineral associations py po ccp ilm mag au tur sch rt spn zrn ms bt ep czo qtz the second stage of mineralization is characterized by pervasive sericitic alteration that is locally developed to an extent where all pre existing mineralogies including quartz are totally destroyed within sericitic domains the stage 2 mineral associations are apy sbt sb mo sp au py po ilm mag ccp sericite chl carbonate cal ep czo qtz 4 4 gold mineralization at big bell was post deformational and post peak metamorphic unlike many archaean gold deposits there are no obvious shear zones controlling the formation of the big bell gold deposit at the structural level exposed either on the surface or in drill core big bell mine was in a low strain domain during the formation of late stage sinistral sub vertical d6 shear zones that are typically concentrated at the granitoid greenstone contacts the retrograde character of the mineralization has been deduced from detailed meso and microstructural observations and demonstrates the emplacement of this gold deposit was very late in the overall orogenic history of the murchison province

assessing brittle volume gain and pressure solution volume loss processes in quartz arenite abstract quartz arenite of the tuscarora sandstone has been deformed by dislocation flow pressure solution and microfracturing of which the last two are most important pressure solution involved shortening with no extension most samples have approximately 20 shortening normal to bedding interpreted to be compaction and a few have up to 20 layer parallel shortening of tectonic origin because there is no extension these shortenings resulted in an equivalent amount of bulk volume loss multiple sets of microfractures in the form of fluid inclusion planes and microveins account for up to 10 extension and bulk volume increases up to 17 when both microfracture volume gains and pressure solution volume losses are considered together all samples show a net bulk volume loss ranging from 14 to 35 changes in material volume are different than bulk volume because of the presence of porosity at the time of pressure solution whereas all samples show bulk volume losses most samples show net material volume gains of up to 16 with only those having experienced both compactional and tectonic pressure solution showing material volume losses pressure solution during compaction can account for most but not all cement compactional pressure solution surfaces do not extend into pore filling cement suggesting that much of the cement was externally derived after compaction therefore the flux of material may have been considerably greater than the material volume changes would indicate

temporal scaling of groundwater discharge in dual and multicontinuum catchment models this paper presents a multicontinuum approach to model fractal temporal scaling of catchment response in hydrological systems the temporal scaling of discharge is quantified in frequency domain by the transfer function h x which is defined as the ratio between the spectra of catchment response and recharge time series the transfer function may scale with frequency x as h x x2b while the classical linear and dupuit models predict exponents of b52 and b51 observations indicate scalings with noninteger exponents b such behaviors have been described by multifractal models which however often lack a relation to the medium characteristics we revisit and extend the classical linear dupuit aquifer models and discuss their physical meanings in the light of the resulting aquifer dynamics on the basis of these classical models we derive a multicontinuum approach that provides physical recharge models which are able to explain fractal behaviors with exponents 1 2 b 2 furthermore this approach allows to link the fractal dynamics of the discharge process to the physical aquifer characteristics as reflected in the distribution of storage time scales we systematically analyze the catchment responses in the proposed multicontinuum models and identify and quantify the time scales which characterize the dynamics of the catchment response to recharge

stochastic analysis of transport in hillslopes travel time distribution and source zone dispersion 1 a stochastic model is developed for the analysis of the traveltime distribution f in a hillslope the latter is described as made up from a surficial soil underlain by a less permeable subsoil or bedrock the heterogeneous hydraulic conductivity k is described as a stationary random space function and the model is based on the lagrangian representation of transport a first order approach in the log conductivity variance is adopted in order to get closed form solutions for the principal statistical moments of the traveltime our analysis indicates that the soil is mainly responsible for the early branch of f i e the rapid release of solute which preferentially moves through the upper soil the early branch of f is a power law with exponent variable between 1 and 0 5 the behavior is mainly determined by unsaturated transport the subsoil response is slower than that of the soil the subsoil is mainly responsible for the tail of f which in many cases resembles the classic linear reservoir model the resulting shape for f is similar to the gamma distribution analysis of the f moments indicates that the mean traveltime is weakly dependent on the hillslope size the traveltime variance is ruled by the distribution of distances of the injected solute from the river the effect is coined as source zone dispersion the spreading due to the k heterogeneity is less important and obscured by source zone dispersion the model is tested against the numerical simulation of fiori and russo 2008 with reasonably good agreement with no fitting procedure

effects of hydraulic conductivity variability on hillslope scale shallow subsurface flow response and storage discharge relations 1 an important problem in scientific hydrology is accounting for the effect of small scale heterogeneity in lumped representations of flow through landscapes in this work we investigate the effect of lateral variations in hydraulic conductivity on saturated subsurface lateral flow through hillslopes using an idealized model based on the boussinesq equation the model simulates flow over an impervious planar base through heterogeneous conductivity fields in response to simple recharge inputs and periodic recharge events the results indicate that the hillslope scale response depends on the relative importance of topographic and water table potential gradients driving flow the relative magnitude of these drivers is related to a dimensionless variable where water table gradients dominate a network of flow paths channel flow through the hillslope toward high conductivity areas and the response is primarily dependent on the boundary condition at the toe of the hillslope where the topographic gradients dominate the flow is delayed by low conductivity areas producing a power law like response suggesting that high exponents in observed storage discharge relations may be traced to the presence of heterogeneity in the landscape these observations suggest that the nature of the lumped hillslope scale hydrologic models depends on the emergent behaviors that arise at that scale as a result of the interactions between hillslope properties including their variability in space the relationship between the hillslopes and their surrounding landscape elements through the boundary conditions and the temporal variability of the recharge that enters the system

large scale natural gradient tracer test in sand and gravel cape cod massachusetts 3 hydraulic conductivity variability and calculated macrodispersivities hydraulic conductivity k variability in a sand and gravel aquifer on cape cod massachusetts was measured and subsequently used in stochastic transport theories to estimate macrodispersivities nearly 1500 k measurements were obtained by borehole flowmeter tests and permeameter analyses of cores the geometric mean for the flowmeter tests 0 11 cm s is similar to that estimated from other field tests the mean for the permeameter tests 0 035 cm s is significantly lower possibly because of compaction of the cores the variance for the flowmeter 0 24 is also greater than that for the permeameter 0 14 geostatistical analyses applying negative exponential models with and without nuggets reveal similar spatial correlation structures for the two data sets estimated correlation scales range from 2 9 to 8 m in the horizontal and from 0 18 to 0 38 m in the vertical estimates of asymptotic longitudinal dispersivity b 35 0 78 m are similar in magnitude to that observed in the natural gradient tracer test 0 96 m previously conducted at this site

gypsies in the palace experimentalist s view on the use of 3 d physics based simulation of hillslope hydrological response as a fundamental unit of the landscape hillslopes are studied for their retention and release of water and nutrients across a wide range of ecosystems the understanding of these near surface processes is relevant to issues of runoff generation groundwater surface water interactions catchment export of nutrients dissolved organic carbon contaminants e g mercury and ultimately surface water health we develop a 3 d physics based representation of the panola mountain research watershed experimental hillslope using the tough2 sub surface flow and transport simulator a recent investigation of sub surface flow within this experimental hillslope has generated important knowledge of threshold rainfall runoff response and its relation to patterns of transient water table development this work has identified components of the 3 d sub surface such as bedrock topography that contribute to changing connectivity in saturated zones and the generation of sub surface stormflow here we test the ability of a 3 d hillslope model both calibrated and uncalibrated to simulate forested hillslope rainfall runoff response and internal transient sub surface stormflow dynamics we also provide a transparent illustration of physics based model development issues of parameterization examples of model rejection and usefulness of data types e g runoff mean soil moisture and transient water table depth to the model enterprise our simulations show the inability of an uncalibrated model based on laboratory and field characterization of soil properties and topography to successfully simulate the integrated hydrological response or the distributed water table within the soil profile although not an uncommon result the failure of the field based characterized model to represent system behaviour is an important challenge that continues to vex scientists at many scales we focus our attention particularly on examining the influence of bedrock permeability soil anisotropy and drainable porosity on the development of patterns of transient groundwater and sub surface flow internal dynamics of transient water table development prove to be essential in determining appropriate model parameterization copyright 2010 john wiley sons ltd

dissecting the variable source area concept subsurface flow pathways and water mixing processes in a hillslope summary this study uses an instrumented trenched 0 5 ha hillslope in the southern tier of new york state usa to provide new data and insights on how variable source areas and associated flow pathways form and combine to connect rainfall with downstream water flows across a hillslope measurements of water fluxes in the trench upslope water table dynamics surface and bedrock topography and isotopic and geochemical tracers have been combined for a four dimensional space time characterization of subsurface storm flow responses during events with dry antecedent conditions infiltrating rainwater was found to percolate through a prevailing fragipan layer to deeper soil layers with much 33 71 of the total discharge of the hillslope originating from deeper water flow below the fragipan during storm events with wet antecedent conditions and large rainfall amounts shallow lateral flow of event and pre event water above the fragipan occurred and was one magnitude greater than the deeper water flow contribution spatial surface and subsurface water quality observations indicate that water from a distance of up to 56 m contributed runoff from the hillslope during storm events in addition mobilization of total dissolved phosphorus tdp with subsurface flow played a greater role than with overland or near surface flow during all events tdp loads were highest in the total discharge during peak flows 8 11 5 kg ha 1 d 1 except during the largest storm event when tdp concentrations were highly diluted these results have implications for strategies to protect streams and other downstream water recipients from waterborne nutrient and pollutant loading

using the continuum approach to model unsaturated flow in fractured rock the appropriateness of using the continuum approach for simulations of unsaturated flow through fractured rock is examined in a numerical study of water seepage into an underground opening a continuum model is calibrated against data generated with a high resolution model that created discrete flow and seepage behavior probabilistic predictions of injection data and seepage rates are then compared to the values from the discrete model the study shows that reasonable results can be obtained with a calibrated continuum model even for fractured systems in which the underlying flow processes are discrete calibration is a crucial step in this approach because it yields effective model related and process specific parameters the impact of discretization on the estimated parameters is discussed prediction uncertainty is evaluated by means of monte carlo simulations including both the impact of parameter uncertainties and the effect of local heterogeneity in this paper the advantages and limitations of the continuum approach are discussed from a practical perspective which includes a critical examination of project objectives data needs robustness of assumptions and prediction uncertainty

finite strain estimation using anti clustered distributions of points abstract a new method for the estimation of finite strain using spatially anti clustered distributions of points is described besides having been empirically validated via simulation it is also evaluated by means of analysing a deformed spilite containing calcitic amygdules which have retained their originally spheroidal shape as well as elliptical chloritic amygdales with the same ductility as the matrix in which they are embedded there is complete agreement between the results obtained using the rf o method on the chloritic amygdales and those provided by the method now proposed when applied to the centres of the calcitic amygdules

a subordinated kinematic wave equation for heavy tailed flow responses from heterogeneous hillslopes 1 analytical expressions of hillslope scale subsurface stormflow discharge are currently restricted to hillslopes with homogeneous or mildly heterogeneous conductivity fields in steep straight hillslopes with uniform recharge these exhibit a classical piston flow response which arises from an assemblage of impulses all moving at a constant velocity but with different starting locations heterogeneity within a hillslope soil creates variations in the downslope velocity of these impulses which may lead to nonpiston flow responses with either exponential or heavy power law tails the presence of heavy tails suggests that heterogeneity imparts a temporal memory on the motion of the impulses using this assumption a subordinated kinematic wave equation is proposed for moderately to highly heterogeneous hillslopes this equation convolves the piston response from a homogenous hillslope with a stable subordinator the stable subordinator randomizes the time that impulses spend in motion and produces nonpiston solutions with heavy tails through comparisons of synthetic data generated from numerical hillslope simulations with physically realistic parameters this equation faithfully reproduces both early and late time characteristics of heavy tailed flow responses from moderate to highly heterogenous hillslopes a systematic evaluation of hillslope responses under different degrees of heterogeneity revealed a quantitative link between the statistical properties of the heterogeneous random fields and the parameters of the subordination framework this suggests that the subordinator can be parameterized with the physical measurement of hillslope properties