stromatolitic framework of carbonate mud mounds abstract mud mounds are an important phanerozoic reef type generally formed in deeper water on carbonate shelf to basin slopes they commonly contain radiaxial calcite spar filled depositional cavities stromatactis but lack abundant metazoan framebuilders mud mounds are often flanked by steeply dipping bioclastic grainstones and sometimes attained widths and depositional reliefs of over a hundred meters they occasionally occur as basal cores on which developed shallow water metazoan constructed reefs stromatactoid mud mounds are composed of a framework of submarine cemented crudely reticulate masses or a succession of laminar crusts surrounded by cement filled cavities these cavities developed when unconsolidated sediment around the framework was removed by winnowing mud mound frameworks of all ages show strong geometric and petrographic similarities to shallow water cryptalgal structures especially thrombolites unlaminated stromatolites which occur in many phanerozoic shallow water reefs both thrombolites and mud mound frameworks are largely composed of lime mudstone cemented on the sea floor and contain fenestral fabric and diagnostic cryptalgal microstructure their depositional surfaces were irregular not bored or burrowed and rarely encrusted stromatolitic lamina ion although commonly not well developed in the subtidal zone anyway occasionally occurs in mud mounds it is proposed that mud mounds accumulated from organic probably blue green algal binding of locally derived lime mud and bioclasts deposited relatively slowly from suspension patchy distribution of algal mats resulted in areas of both bound and unbound sediment sporadic floodlike episodes of rapid sedimentation however temporarily smothered the living algal mat and also left layers of unbound sediment periods of winnowing washed out unconsolidated unbound sediment and promoted synsedimentary cementation of resulting stromatactoid cavities and algal bound framework

bryozoan faunas in the middle miocene of hungary biodiversity and biogeography a study of the badenian middle miocene marine deposits of hungary yielded a rich bryozoan fauna of 238 species comprising 59 cyclostomes 176 cheilostomes and 3 ctenostomes six palaeobiogeographic groups have been identified among this fauna on the basis of the present day and fossil distribution of the species similarities within the central paratethys and between the central paratethys the mediterranean and the atlantic have then been calculated using jaccard s index the results indicate strong affinities between the central paratethyan basins of hungary austria poland and romania the higher number of species and the lower level of endemism observed in hungary is explained by the vicinity of this basin to the entrance of the water seaway connecting the mediterranean to the paratethys a decrease in taxonomic diversity between the early and the late badenian is also observed accompanied by the absence of most tropical taxa from the late badenian this points towards a less optimal climate and a more pronounced isolation of the badenian sea from the oceanic waters the major result of the comparative study between central paratethyan and mediterranean bryozoan faunas is the presence of numerous common species the number of endemic paratethyan species is however relatively high indicating that the bryozoan faunas of both seas evolved in a relative isolation the exchange of faunas between the mediterranean and the paratethys was probably regulated by an anti estuarine circulation permitting an easier incursion of mediterranean species into the paratethys but hindering the paratethyan endemics from entering the mediterranean the stronger affinity between hungarian and mediterranean faunas also shows that this basin was closer to the entrance of the water seaway connecting the two areas and thus the mediterranean species entered more easily the similarity index between central paratethys and atlantic faunas is much lower than with the mediterranean this indicates that the palaeobiogeographic domain formed by the mediterranean and the paratethys was relatively homogeneous during the middle miocene and that the relationships with the atlantic were weaker exchange of benthic organisms between the central paratethys and the indo pacific during the middle miocene is considered here as extremely improbable

quantitative analysis and paleoecology of earliest mississippian microbial reefs gudman formation queensland australia not just post disaster phenomena small 30 m diameter 9 m thick reefs in the gudman formation of queensland australia are the oldest known mississippian reefs occurring very near the devonian carboniferous boundary following late devonian extinction events they occur in high energy shallow oolitic grainstones and consist of 70 microbialite and bound detritus on the basis of point count analysis skeletal organisms including potential frame building rugose and tabulate corals ramose bryozoans crinoids and algae occur in growth position but account for only 4 4 of sampled framework the microbial framework was syndepositionally rigid on the basis of 1 vertical and overhanging relief in a high energy setting 2 export of framework intraclasts 3 hard substrate encrusting organisms 4 abundant hard rock borings and 5 neptunian dikes unusually for mississippian reefs stromatolites make up a large part of the framework 32 but more typical thrombolites are equally abundant interfingering of skeletal organisms and microbialites suggests that they grew in welloxygenated normal marine waters and that microbial biofilms competed effectively with skeletal organisms for available substrate abundant and diverse co occurring skeletal flora and fauna are inconsistent with interpretations of gudman stromatolites as post extinction disaster taxa hence gudman reefs are stromatolite rich examples of a larger class of microbialite dominated phanerozoic reefs that occurred with abundant skeletal metazoans in normal marine settings

multirate flowing fluid electric conductivity logging method the flowing wellbore electric conductivity logging method involves the replacement of wellbore water by de ionized or constant salinity water followed by constant pumping with rate q during which a series of fluid electric conductivity logs are taken the logs can be analyzed to identify depth locations of inflow and evaluate the transmissivity and electric conductivity salinity of the fluid at each inflow point the present paper proposes the use of the method with two or more pumping rates in particular it is recommended that the method be applied three times with pumping rates q q 2 and 2q then a combined analysis of the multi rate data allows an efficient means of determining transmissivity and salinity values of all inflow points along a well with a confidence measure as well as their inherent or far field pressure heads the method is illustrated by a practical example

ecospace variability along a carbonate platform at the northern boundary of the miocene reef belt upper langhian austria the south western edge of the leitha mountains in the southern vienna basin austria exposes parts of an upper langhian middle badenian shallow water 30 m carbonate platform the study of its ecospace comprises sedimentological and palaeontological data of 4 up to 36 m thick carbonate sections of the mullendorf quarries which have been logged and subjected to detailed investigation and sampling the sedimentary record is dominated by coralline algal debris sands which represent 7 distinct lithofacies bioclastic coralline algal mollusc facies hyotissa facies isognomon facies coral facies rhodolith facies bryozoan facies all these facies are described in detail in respect to lithology and biota and are palaeoecologically interpreted striking features of these limestone successions are periodical intercalations of coral and mollusc rich horizons their formation had been triggered by water turbidity and low amplitude changes in relative sea level these relations are especially interesting as the platform carbonates formed at the northern edge of the langhian peri mediterranean reef belt water turbidity as ecological master factor and depth played the fundamental role in ecosystem and community expression within ecospace the lateral distribution and the ecological relations between the various facies types allow proposing an ecospace occupation model

bryozoa foraminifera and calcareous nannoplankton as environmental proxies of the bryozoan event in the middle miocene of the central paratethys czech republic abstract in order to improve the reliability of using bryozoans as an indicator of the palaeoenvironment a detailed study of the ancient environmental parameters of the middle miocene bryozoan event was carried out using foraminifera calcareous nannoplankton and oxygen and carbon stable isotope data abundant occurrence of bryozoa in the middle miocene of the central paratethys was an isochronous event which can be correlated with m6 zone between fo of orbulina suturalis and lo of praeorbulina circularis 14 8 14 58 ma the ecosystems of the central paratethys marine basins during this time were generally influenced by the middle miocene climatic optimum and the large transgression which covered the central paratethys basins with tropical subtropical waters these events triggered the expansion of bryozoa which settled in the narrow shallow water zone of the basin and were accompanied by epiphytic foraminifera such as asterigerinata lobatula and elphidium and large foraminifera such as amphistegina rarely cibicidoids although foraminiferal assemblages show only small palaeoenvironmental variations bryozoan species compositions remarkably vary according to palaeoenvironments in this study four clusters with differing bryozoan assemblages can be distinguished in shallow water environment as follows 1 reteporella hornera verrucosa assemblage indicative of a high energy environment 2 buffonellodes rhynchozoon assemblage occurred on carbonate substratum with seagrass meadows influenced by the middle miocene warm water incursion 3 smittina metrarabdotos assemblage indicative of toleration of suboxic zone in sediment 4 schizomavella tenella schizoporella tetragona assemblage recorded almost in all shallow water environments this cluster probably represents species with high adaptation potential exceptionally deeper water conditions were inferred at one section and represented by a tervia irregularis dominated assemblage this assemblage was only present for a short period of time

signatures in flowing fluid electric conductivity logs flowing fluid electric conductivity logging provides a means to determine hydrologic properties of fractures fracture zones or other permeable layers intersecting a borehole in saturated rock the method involves analyzing the time evolution of fluid electric conductivity fec logs obtained while the well is being pumped and yields information on the location hydraulic transmissivity and salinity of permeable layers the original analysis method was restricted to the case in which flows from the permeable layers or fractures were directed into the borehole inflow recently the method was adapted to permit treatment of both inflow and outflow including analysis of natural regional flow in the permeable layer a numerical model simulates flow and transport in the wellbore during flowing fec logging and fracture properties are determined by optimizing the match between simulation results and observed fec logs this can be a laborious trial and error procedure especially when both inflow and outflow points are present improved analyses methods are needed one possible tactic would be to develop an automated inverse method but this paper takes a more elementary approach and focuses on identifying the signatures that various inflow and outflow features create in flowing fec logs the physical insight obtained provides a basis for more efficient analysis of these logs both for the present trial and error approach and for a potential future automated inverse approach inflow points produce distinctive signatures in the fec logs themselves enabling the determination of location inflow rate and ion concentration identifying outflow locations and flow rates typically requires a more complicated integral method which is also presented in this paper

depth bed slope and wave climate dependence of long term average sand transport across the lower shoreface abstract we analyse measured 46 year changes in nearshore bathymetry to quantify rates of net shore normal sand transport q x in 10 20 m depths at northern gold coast australia these are significant both in understanding local disequilibrium shoreface evolution and as prototype data that may be used to assess theoretical predictive methods this analysis is feasible because the migration history of a nearby river mouth has formed a disequilibrium shoreface lobe that is evolving towards an equilibrium profile shape which is identified in adjacent non lobe profiles the data include various profile transect surveys from 1966 to 2012 sediment characteristics and locally recorded wave conditions a generally applicable form of q x that is a function of both a depth dependent horizontal bed transport forcing component and bed slope q x q x h s is developed and quantified in terms of long term average behavior for this site dependence of the forcing component on wave climate is shown from higher than average q x derived from the lobe response during a recent five year period with abnormally high waves our q x h s quantifies the balance between generally shoreward wave boundary layer sand transport and the opposing effect of the seabed slope as incorporated in the predictive methods

flowing fluid electric conductivity logging for a deep artesian well in fractured rock with regional flow the flowing fluid electric conductivity ffec logging method is a well logging technique that may be used to estimate flow rate salinity transmissivity and hydraulic head of individual fractures or high permeability zones intersected by a wellbore wellbore fluid is first replaced with fluid of a contrasting electric conductivity then repeated fec logging is done while the well is pumped zones where fluid flows into the wellbore show peaks in the fec logs which may be analyzed to infer inflow rate and salinity of the individual fractures conducting the procedure with two or more pumping rates multi rate ffec logging enables individual fracture transmissivity and hydraulic head to be determined here we describe the first application of the multi rate ffec logging method to an artesian well using a 500 m well in fractured rock at horonobe japan an additional new factor at the site is the presence of regional groundwater flow which heretofore has only been studied with synthetic data ffec logging was conducted for two different pumping rates several analysis techniques had to be adapted to account for the artesian nature of the well the results were subsequently compared with independent salinity measurements and transmissivity and hydraulic head values obtained from packer tests in the same well despite non ideal operating conditions multi rate ffec logging successfully determined flow rate salinity and transmissivity of 17 conducting fractures intercepted by the logged section of the borehole including two fractures with regional groundwater flow predictions of hydraulic head were less accurate a not unexpected result in light of operational problems and the form of the equation for hydraulic head which involves the difference between two uncertain quantities this study illustrates the strengths and weaknesses of the multi rate ffec logging method applied to artesian wells in conjunction with previous studies it demonstrates the usefulness of the method for a broad range of conditions encountered in subsurface fractured rock

integrated borehole logging methods for wellhead protection applications modeling of ground water infiltration and movement in the wellhead area is a critical part of an effective wellhead protection program such models depend on an accurate description of the aquifer in the wellhead area so that reliable estimates of contaminant travel times can be used in defining a protection area geophysical and hydraulic measurements in boreholes provide one of the most important methods for obtaining the data needed to specify wellhead protection measures most effective characterization of aquifers in the wellhead vicinity results when a variety of geophysical and hydraulic measurements are made where geophysical measurements can be calibrated in terms of hydraulic variables and where measurements are made at somewhat different scales of investigation the application of multiple geophysical measurements to ground water flow in the wellhead area is illustrated by examples in alluvial fractured sedimentary and fractured crystalline rock aquifers data obtained from a single test well are useful but cannot indicate how conductive elements in the aquifer are connected to form large scale flow paths geophysical and hydraulic measurements made in arrays of observation boreholes can provide information about such large scale flow paths and are especially useful in specifying aquifer properties in wellhead protection studies

a new type of messinian composite microbialitic build up salemi sicily italy abstract a new type of metric scale composite patch reef is described in the messinian sedimentary rocks from the vicinity of salemi western sicily these build ups are composed of two distinctive parts 1 a steep sided dome shaped microbial mound with thrombolitic fabric and encrusting organisms 2 a coral microbial build up covering the microbialitic mound in which coral colonies are coated with microbialites these are associated with various encrusting organisms the accretion of the microbialitic mound is characterized by the development of botryoidal micritic aggregates and skeletons of melobesians encrusting foraminifers bryozoans serpulids and cemented bivalves the accretionary process involving the microbialite development appears to have been homogeneous within different parts of the composite microbialitic build up as in other similar messinian build ups of the mediterranean consequently it is considered that microbial growth continued throughout messinian times in mediterranean regions being recorded in a wide range of habitats and paleoenvironments

high resolution palynological analysis in late early middle miocene core from the pannonian basin hungary climatic changes astronomical forcing and eustatic fluctuations in the central paratethys high resolution palynological analysis in the karpatian sarmatian late early middle miocene interval of the borehole tengelic 2 hungary reveals the existence of a forest organized in altitudinal belts developed in a subtropical warm temperate humid climate reflecting the so called miocene climatic optimum pollen changes from the late early miocene to the middle miocene are related to climatic variations values of mean annual temperature ta between 18 and 20 8c and mean annual precipitation pa between 1200 and 1400 mm have been estimated bclimatic amplitude methodq for the badenian decreasing during late badenian and sarmatian ta and pa about 16 8c and 1100 mm have been interpreted as a climatic cooling correlated with the bmonterey cooling eventq and related to the development of the east antarctic ice sheet eais alternation in pollen taxa thermophilous vs altitudinal elements reflects the astronomical forcing on temperature and precipitation and then on vegetation where obliquity and eccentricity cycles dominated eustatic changes determine pinus and pinaceae and dinocyst variations

stromatolite decline a reconsideration the prevailing concept of phanerozoic stromatolite decline is considered too simplistic changes in stromatolite character and proportion to other lithologies after the precambrian can be explained as responses to substrate competition and changing sedimentological conditions caused by the evolution of skeletal metazoans grazing pressure was likely insignificant as a limiting factor

characterisation of fractured carbonate aquifers using ambient borehole dilution tests abstract fractured carbonate aquifers derive their transmissivity essentially from a well developed network of solutionally enhanced fractures and conduits that can lead to high groundwater velocities and high vulnerability to contamination of water quality characterisation of the variation of hydraulic properties with depth is important for delineating source protection areas characterising contaminant fate and transport determination of the effectiveness of aquifer remediation and parameter estimation for models in this work ambient open borehole uniform and point injection dilution tests were conducted on observation boreholes in the unconfined cretaceous chalk aquifer of east yorkshire uk and interpreted in conjunction with other data via the implementation of a new work flow this resulted in the characterisation of flow in these boreholes and the inference of properties such as groundwater flow patterns and velocities in the surrounding aquifer formation our workflow allowed sections of open boreholes showing horizontal versus vertical flow to be distinguished and the magnitude of such flows and exchanges with the aquifer to be determined flow within boreholes were then used to characterise i presence and direction of vertical hydraulic gradients ii nature and depth distribution of flowing features iii depth interval porosity and permeability estimation of the flowing features from overall borehole transmissivity and geophysical image or caliper logs iv groundwater velocity estimation in the surrounding aquifer discrete flowing features were distributed across the range of depths sampled by the observation boreholes typically up to 45 60 mbgl but the majority were located in the zone of water table fluctuation marked by solutionally enlarged flow features quantitative interpretation of both uniform injection tracer distributed throughout the open borehole section and point injection slug of tracer introduced at targeted depth yielded vertical velocities within the borehole water column in broad agreement with those measured by flow logging depth specific fracture kinematic porosities inferred from the ambient dilution data combined with long interval pump test and geophysical log data ranged between 3 7 10 4 4 1 10 3 with an average of 2 1 10 3 these values were in excellent agreement with those from other methods applied to the same aquifer such as larger scale pumping tests a new approach to estimation of groundwater velocities from the dilution test data using externally measured hydraulic gradients gave inferred horizontal groundwater velocities ranging between 60 and 850 m day in full agreement with those from previously conducted borehole to borehole tracer tests these results confirm that the studied aquifer is karstic with rapid preferential pathways which have implication for flow and transport modelling and pollution vulnerability our study results indicate that ambient single borehole dilution approaches can provide an inexpensive and reliable approach for the characterisation of fractured and karstic aquifers

a multidisciplinary fractured rock characterization study at raymond field site raymond ca abstract a dedicated field site was developed and a suite of experiments were conducted in the sierra nevada foothills near the town of raymond ca to develop and test a multi disciplinary approach to the characterization of groundwater flow and transport in fractured rocks a wealth of geologic hydrologic and geophysical data was collected at the site using a variety of unique tools a cluster of nine approximately 90 m deep boreholes were drilled at the site in a v shaped pattern with an angle of 60 the boreholes are spaced 7 5 15 30 and 60 m from the central borehole various geophysical and hydrologic tests were conducted in and between these boreholes integration of cross hole radar and seismic tomography borehole flow surveys and images from a new digital borehole scanner indicated that groundwater flow is mainly confined to a few sub horizontal fracture zones a unique suite of hydraulic tests were conducted in which three to four intervals in each of the nine boreholes were isolated using pneumatic packers some 130 injection tests were conducted and more than 4100 cross hole transient pressure measurements were obtained a computer algorithm was developed to analyze such massive interference data systematically as a result of the analysis an image of the fracture connections emerged which is consistent with the geophysical data high precision tiltmeters were effective in remotely characterizing the preferential flow path several radial convergent tracer tests were conducted by injecting a mixture of several conservative tracers and one sorbing tracer deuterium fluorescein lithium bromide and polystyrene micro spheres some differences between the breakthrough curves are observed which may be due to possible differences among so called conservative tracers some characterization tools were found to be more effective than others in locating flowing fractures however no single tool was almighty characterization of fractured rock is extremely challenging and requires a stepwise and well thought approach which is basically a good old scientific approach prediction of transport based on the characterization results is even more challenging and one should always bear in mind that it is virtually impossible to uniquely characterize a fractured rock

mosaic of environments recorded by bryozoan faunas from the middle miocene of hungary the marine sediments of the badenian middle miocene of hungary pannonian basin central paratethys are composed of abundant bryozoan skeletal grains seventy one bulk samples collected at 18 localities outcrops and boreholes yielded a total number of 238 bryozoan species in order to reconstruct the badenian palaeoenvironments the present study investigates the composition of this very diverse fauna using a combination of statistical and palaeoecological methods the statistical analyses make use of cluster analysis and non metric multi dimensional scaling the palaeoecological approaches are based on the known ecological requirements of the bryozoan colonial growth forms and of the numerous extant species five facies have first been differentiated on the basis of sedimentological and palaeontological features coral buildups coralline algal limestones biocalcarenites sands and marls each of them is characterized by the abundance the diversity and the types of growth forms of the bryozoans the palaeoecological statistical and facies analyses further permitted to identify four depositional settings carbonate platform distal and proximal terrigenous platform slope and basin these environments developed at depths between 0 to about 300 m in a mixed carbonate siliciclastic depositional system skeletal production and spatial distribution of carbonate factories were predominantly controlled by terrigenous input this resulted in a complex mosaic of facies habitats where rich bryozoan faunas could thrive many warm water organisms among them foraminifers zooxanthellate corals molluscs bryozoans and echinoids were recorded from the study sites the coexistence of coralgal and bryomol carbonate skeletal assemblages in this subtropical setting is explained mostly by variations in the productivity of surface waters periods of nutrient enrichment and increased benthic eutrophication affected coral diversity and abundance in favour of bryozoans

application of multirate flowing fluid electric conductivity logging method to well dh 2 tono site japan 1 in the flowing fluid electric conductivity fec logging method well bore fluid is replaced with deionized water following which fec profiles in the well bore are measured at a series of times while the well is pumped at a constant rate locations where fluid enters the well bore show peaks in the fec logs which are analyzed to infer inflow strengths and salinities of permeable features intersected by the borehole in multirate flowing fec logging the flowing fec logging method is repeated using two or more pumping rates the results coupled with those of a conventional well test over the entire borehole enable the transmissivities and inherent pressure heads of permeable features to be determined multirate fec logging is carried out on a deep borehole in fractured granitic rock using three different pumping rates results identify 19 hydraulically conducting fractures and indicate that transmissivity pressure head and salinity vary significantly among them using three pumping rates rather than the minimum number of two permits an internal consistency check on the analysis that provides a measure of the uncertainty of the results good comparisons against static fec profiles and against independent chemical geological and hydrogeological data have further enhanced confidence in the results of the multirate flowing fec logging method

occurrence and significance of microbialites in the uplifted tasmaloum reef sw espiritu santo sw pacific abstract in the sw pacific ocean subduction of the d entrecasteaux ridge system has caused rapid uplift of the central new hebrides island arc the maximum uplift rate of 6 mm yr 1 occurs along the southwest coast of espiritu santo island near tasmaloum the tasmaloum uplifted reef sequence internal structure which is strongly linked to its tectonic context was investigated through a series of drill holes to depths up to 42 m although a stable tropical coast would undergo approximately 120 m of post glacial sea level rise the net relative sea level rise on such a rapidly uplifting coast is only about 20 m colonization of the tasmaloum fringing reef occurred by 24 ka upon a pre reef substrate composed of a thick bioclastic sand formation accumulated during the last glacial period during the post glacial sea level rise the vertical succession of reef assemblages reflects environmental and bathymetric variations controlled by the interplay of rapid but variable rates of sea level rise and more or less constant uplift of 5 6 mm yr 1 microbialite crusts composed of high magnesian calcite laminae occur in the tasmaloum reef from 20 to 6 ka and are particularly abundant from 16 to 10 ka the development of microbialite crusts is related to nutrient enrichment of interstitial waters through mixing with meteoric groundwater after 6 ka when sea level ceased rising in the region and continuing uplift caused rapid emergence of the reef microbialites disappear within the subtidal assemblages several explanations can be put forward for their disappearance in particular nutrient input changes are a likely cause a new hydrologic and oceanographic regime was established when sea level ceased rising this change was accompanied by warming of tropical waters

late miocene halimeda alga microbial segment reefs in the marginal mediterranean sorbas basin spain a 6 ma messinian late miocene bioherm unit on the southern slope of the sorbas basin se spain contains numerous biotically diverse lensoid patch reefs that formed on a shelf to basin slope during a cycle of relative sea level change halimeda reefs are the largest and most complex of the patch reefs and are divisible into core cap and flank facies on the upper and midslope they are up to 40 m thick and 400 m long they become smaller downslope the core consists of jumbled halimeda segments released by spontaneous disaggregation of the alga the segments were stabilized close to their sites of growth and rapidly lithified by micritic and peloidal microbial crusts residual cavities were further veneered by isopachous marine cements flank facies consisting of bedded packstones to rudstones form wedge shaped units lateral to the mounds cap facies consist of bioclastic calcarenites calcirudites and microbial carbonates synsedimentary lithification assisted rapid accretion and inhibited off mound export of sediment allochthonous reef derived blocks on the mid slope reflect penecontemporaneous rigidity of the halimeda bioherms proximal porites coral frame patch reefs associated with calcarenites were located near the shelf margin during the initial lowstand stage halimeda segment reefs associated with calcarenites and silty marls developed on the midslope and bivalve bryozoan serpulid reefs formed on the lower slope in silty marls with occasional turbidites during the transgressive stage coral patch reefs near the shelfbreak were overgrown by halimeda during highstand progradation cap facies spread basinward as a sheet connecting many of the midslope patch reefs these ancient analogues differ from most modern halimeda reefs in being discrete laterally restricted patch reefs surrounded by marly sediment and located on a slope they are however broadly comparable in biota thickness and depositional depth intense early lithification by microbial crusts and marine cements is an important feature of these messinian segment reefs it has not been reported from modern examples

inflow and outflow signatures in flowing wellbore electrical conductivity logs flowing wellbore electrical conductivity logging provides a means to determine hydrologic properties of fractures fracture zones or other permeable layers intersecting a borehole in saturated rock the method involves analyzing the time evolution of fluid electrical conductivity logs obtained while the well is being pumped and yields information on the location hydraulic transmissivity and salinity of permeable layers as well as their initial or ambient pressure head earlier analysis methods were restricted to the case in which flows from the permeable layers or fractures were directed into the borehole more recently a numerical model for simulating flowing conductivity logging was adapted to permit treatment of both inflow and outflow including analysis of natural regional flow in the permeable layer however determining the fracture properties with the numerical model by optimizing the match to the conductivity logs is a laborious trial and error procedure in this paper we identify the signatures of various inflow and outflow features in the conductivity logs to expedite this procedure and to provide physical insight for the analysis of these logs generally inflow points are found to produce a distinctive signature on the conductivity logs themselves enabling the determination of location inflow rate and ion concentration in a straightforward manner identifying outflow locations and flow rates on the other hand can be done with a more complicated integral method running a set of several conductivity logs with different pumping rates e g half and double the original pumping rate provides further information on the nature of the feed points in addition to enabling the estimation of flow parameters from conductivity logs an understanding of the conductivity log signatures can aid in the design of follow up logging activities

inverting fluid conductivity logs for fracture inflow parameters fluid electrical conductivity logging experiments introduced by tsang et al 1990 represent a new technology for studying the hydraulic properties of discrete fractures in open boreholes these experiments consist of replacing water in the well bore with deionized water and then pumping the well to induce formation water to return to the well bore during and after the fluid exchange the entire well is logged to measure fluid electrical conductivity fec at locations where formation water enters the well there are abrupt increases in the borehole fec thereby revealing the location of hydraulically conductive fractures as pumping continues high fec water moves up the well bore at a rate proportional to the total inflow rate below the observation point inflow rates and fecs of formation water associated with each fracture can be inferred by modeling the fec profiles with the one dimensional advective dispersion equation in this paper i present an inverse model which estimates the inflow rates and formation fec values that optimally fit observed fec logs acquired during fluid exchange experiments described by tsang et al 1990 with this inverse model inflow rates are constrained by the rate at which the well is pumped during the experiment the forward model is solved numerically using a control volume finite difference scheme with power law upstream weighting and source term linearization the inverse problem is solved using the gauss newton iterative method the rows of the jacobian matrix or the sensitivity coefficients are calculated numerically with the same algorithm that solves the forward problem both constrained and unconstrained inverse models are used to interpret fluid logging experiments performed in research wells penetrating piedmont rocks of north carolina

determination of fracture inflow parameters with a borehole fluid conductivity logging method there is much current interest in determining the flow characteristics of fractures intersecting a well bore in order to provide data for use in estimating the hydrologic behavior of fractured rocks inflow rates from these fractures into the well bore are usually very low moreover in most cases only a few percent of the fractures identified by core inspection and geophysical logging actually conduct water the rest being closed clogged or isolated from the water flow system a new procedure is proposed and a corresponding method of analysis developed to locate water conducting fractures and obtain fracture inflow rates by means of a time sequence of electric conductivity logs of the borehole fluid the physical basis of the analysis method is discussed and the procedure is applied to an existing set of data which shows initiation and growth of nine conductivity peaks in a 900 m section of a 1690 m borehole corresponding to nine water conducting fractures intersecting the borehole by applying our analysis to these nine peaks the flow rates and the salinity of the water from these fractures are determined these results are used with other information to obtain transmissivities of the nine fractures which are validated against independent hydraulic measurements by packer tests the salinities measured in fluids from the fractures are also validated against salinity values obtained by chemical sampling of fluids from different depths of the borehole the applicability of this technique is discussed in the context of a borehole testing program

coral microbialite environment in a middle miocene reef of hungary abstract the presence of microbial crusts microbialites is reported here for the first time from a middle miocene badenian coral reef in hungary the succession of initiation and development of the microbial crusts is described in relation to the reef architecture the main features of the palaeoenvironment are discussed with focus on the associated invertebrate faunas mostly corals molluscs bryozoans and crabs we conclude that the microbial crusts developed under normal marine conditions and were a significant contributor to reef framework development including its strengthening through calcification of the microbial organisms microbialites are anticipated in other early and middle miocene coral reef occurrences of the mediterranean paratethys realm and to date may have simply escaped positive recognition

stromatolites associated with coralgal communities in holocene high energy reefs thick laminar to columnar stromatolitic growths encrust typical high energy coralgal reef communities in a french polynesian outer reef edge the reef communities accumulated during vertical growth from 5870 100 yr b p to the present at depths never exceeding 5 m below mean sea level oxygen and carbon isotope records and high calcification rates of stromatolite encrusted corals strongly suggest that for about the past 6000 yr the local environmental conditions were optimal for reef development accordingly stromatolites can grow in healthy holocene reefs because similar stromatolites have been recorded in other cenozoic reefs we suggest that microbial structures may have played a more prominent role in cenozoic reef growth than is currently recognized

microbialite morphology structure and growth a model of the upper jurassic reefs of the chay peninsula western france abstract during the early kimmeridgian the northern margin of the aquitaine basin western france is characterised by a significant development of coral reefs the reef formation of the chay peninsula comprises two main reefal units in which the microbial structures can contribute up to 70 of framework the microbial crusts which played an important role in the stabilisation and growth of the reef body show the characteristic clotted aspect of thrombolitic microbialites corals are the main skeletal components of the build ups the bioconstructions of the chay area are thus classified as coral thrombolite reefs four main morpho structural types of microbial crusts are distinguished 1 pseudostalactitic microbialites on the roof of intra reef palaeocaves 2 mamillated microbialites found either on the undersides or on the flanks of the bioherms 3 reticular microbialites in marginal parts of the reefs and between adjacent bioconstructed units and 4 interstitial microbialites in voids of bioclastic deposits thrombolitic crusts developed on various substrates such as corals bivalves or bioclasts the thrombolites formed a dense clotted and or micropeloidal microbial framework in which macro and micro encrusters also occur variations in accumulation rate strongly influenced the reef morphology in particular its relief above the sediment surface the coalescence of the coral microbialite patches created numerous intra reef cavities of metre scale dimensions the direction of microbial growth which defined the macroscopic microbialite forms strongly depended on the position within the reef framework but was also controlled by water energy accumulation rate and light availability

nature and environmental significance of microbialites in quaternary reefs the tahiti paradox drill cores from the bamer reef edge of tahiti exhibit 85 93 m thick coralgal sequences recording at least 13 500 years of continuous reef growth in optimal environmental conditions the cored reef sequences form an overall shallowingupward succession with assemblages of branching or massive colonies of porires at the base overlain by a robust branching community acropom gr dmmi robirstn heavily encrusted by coralline algae sessile vermetid gastropods and arborescent foraminifers which grew at depths less than 6 m microbialites generally form the last stage of encrustation of coral colonies or more commonly of related encrusting organisms thus appearing as a major structural component of the reef sequence where they may locally form 809 of the rock by volume they developed in an open cavity system of the reef framework with freely circulating normal marine water microbialites include laminated crusts and clotted micritic masses commonly associated in compound crusts probably feflecting differences in the composition of the involved biological communities and in biomineralization processes that controlled the accretion of the crusts the isotopic composition of the microbialites 2 05 to 3 92 i they underwent also indivitlual processes of biominrlali2ation besicles the overall decrease in lizht and enqy conditions rttlecting progressive burial by conil growth the widespread development of microbialites within the reef framework may be related to increased alkalinity and niitrient availability in interstitial waters due to temstrial groundwwr seepage and puiodic runoffs the tlevelopment of micrubialites in the cryptic niches of the reef framework ceased about 6000 years

analysis of 6 year fluid electric conductivity logs to evaluate the hydraulic structure of the deep drill hole at outokumpu finland over the last two decades the flowing fluid electric conductivity ffec logging method has been applied in boreholes in the well testing mode to evaluate the transmissivity hydraulic head and formation water electrical conductivity as a function of depth with a resolution of about 10 20 cm ffec profiles along the borehole are obtained under both shut in and pumping conditions in a logging procedure that lasts only 3 or 4 days a method for analyzing these ffec logs has been developed and successfully employed to obtain formation parameters in a number of field studies the present paper concerns the analysis of a unique set of ffec logs that were taken from a deep borehole reaching down to 2 5 km at outokumpu finland over a 6 year time period the borehole intersects paleoproterozoic metasedimentary granitoid and ophiolite derived rocks after the well was drilled completed and cleaned up ffec logs were obtained after 7 433 597 948 and 2036 days in analyzing these five profiles we discovered the need to account for salinity diffusion from water in the formation to the borehole analysis results include the identification of 15 hydraulically conducting zones along the borehole the calculation of flow rates associated with these 15 zones as well as the estimation of the variation of formation water electrical conductivity as a function of depth the calculated flow rates were used to obtain the tentative hydraulic conductivity values at these 15 depth levels

application of direct fitting mass integral and multirate methods to analysis of flowing fluid electric conductivity logs from horonobe japan 1 the flowing fluid electric conductivity ffec logging method is an efficient way to provide information on the depths salinities and inflow strengths of individual conductive features intercepted by a borehole without the use of specialized probes using it in a multiple flow rate mode allows in addition an estimate of the transmissivities and inherent far field hydraulic heads in each of the conductive features the multirate method was successfully applied to a 500 m borehole in a granitic formation and reported recently the present paper describes the application of the method to two zones within a 1000 m borehole in sedimentary rock which produced for each zone three sets of logs at different pumping rates each set measured over a period of about 1 day the data sets involve several complications such as variable well diameter gradual water level decline in the well during logging possible fluid flow through the unfractured rock matrix and effects of drilling mud various techniques were applied to analyze the ffec logs direct fitting mass integral and the multirate method mentioned above in spite of complications associated with the tests analysis was able to identify 44 hydraulically conducting fractures distributed over the depth interval 150 775 m below ground surface the salinities in fec and transmissivities and hydraulic heads in dimensionless form of these 44 features were obtained and found to vary significantly among one another these results were compared with transmissivity and head values inferred from eight packer tests that were conducted in this borehole over the same depth interval ffec results were found to be consistent with packer test results thus demonstrating the robustness of the ffec logging method under nonideal conditions

middle miocene latitudinal climatic gradient in western europe evidence from pollen records abstract pollen analysis of sections spanning the middle miocene langhian and serravallian from southern spain to switzerland has been carried out with the aim of reconstructing the existing latitudinal environmental gradient floral assemblages indicate a tropical subtropical to warm temperate climate for the entire area during the middle miocene the presence in all pollen spectra of taxa with high temperature requirements demonstrates that the latitudinal gradient in temperature was relatively low the development of a diverse subarid flora in southern spain including neurada lygeum prosopis calligonum nitraria caesalpiniaceae etc points to a very dry climate with a marked seasonality these features clearly indicate that a very warm and dry climate i e a steppe environment was already present during the langhian in the northwestern mediterranean area on the other hand milder conditions are progressively inferred towards the north as subdesertic elements gradually disappeared and taxa with higher water requirements increased the latter dominates the pollen assemblages in the eastern central part of france and switzerland thus precipitations would have been evenly distributed throughout the year we interpret this gradient from subdesertic vegetation in the south to humidity adapted plant environments in the north as the result of a latitudinal gradient in precipitation