unsaturated zone hydrostratigraphies a novel archive of past climates in dryland continental regions natural chemical tracers contained in moisture within unsaturated zone usz sediments have very significant potential as a novel archive of past climate and palaeoenvironmental conditions in dryland environments however this potential has yet to be fully realised the tracer signature is established in the near surface zone with evapotranspiration processes enriching the concentration inherited from input from atmospheric deposition predominantly rainfall this pore moisture tracer signature then moves vertically through the usz sediments toward the water table producing a hydrostratigraphy that with increasing depth records changes to the moisture balance at the surface through time the small fluxes of water through the usz in dryland climates means that this hydrostratigraphy approach is particularly valuable in these environments for providing climate records longer than the instrumental data period this paper sets out the current state of the art in the use of the usz as an archive we explain the nature of the usz the basis of the tracer technique and also the field and sampling methodologies employed examples of application worldwide by broad geographic region are also evaluated this shows that the usz hydrostratigraphy approach can be used across three key timescales i decadal to multi decadal resolution records covering hundreds of years that provide information about recent climate fluctuations and patterns of land use change ii multi decadal through to millennial scale length records which may record wetter and drier events down to decadal scale resolution and iii last interglacial through to the holocene records of lower resolution that indicate broad shifts over multi millennial timescales we also explore the questions and challenges surrounding the depositional flux of tracer inputs and the extent to which infiltration is non uniform before setting the agenda for their future potential use alongside related proxies for palaeohydrology

characterization of the micropore systems in high rank coal reservoirs of the southern sichuan basin china to gain a better understanding of the characteristics of micropore systems in high rank coal reservoirs 51 coal core samples collected from 16 wells were examined by maceral analysis proximate analysis scanning electron microscopy observation low temperature nitrogen gas adsorption and nuclear magnetic resonance nmr the results show that pores in coals can be divided into plant tissue hole blowhole dissolved pore and intercrystalline pore and they have three structure shapes open pore semiclosed pore and ink bottle pore the total specific surface area brunauer emmet teller bet ranges from 0 611 to 7 to averaged at the total pore volume barrett joyner halenda model bjh ranges from 0 0018 to 0 0001 to with an average of and it shows a good positive relationship with the adsorption amount shows a good positive relationship with the total and the average pore size ranges from 5 775 to 17 842 nm pores that are smaller than 5 nm make up the main contribution to the pore surface area and those larger than 10 nm contribute greatly to the pore volume inertinite rich coals have higher total specific surface area pore volume pore size and adsorption capacity than those in vitrinite rich coals lopingian coal reservoirs are characterized by low porosity and extremely low permeability obtained from nmr tests and the permeability has a positive correlation with the porosity the average permeability of inertinite is almost twice that of vitrinite

geological controls on coal quality of the yili basin xinjiang northwest china abstract this study summarizes the results of geological petrographical geochemical and mineralogical analyses performed to determine the geological controls on coal quality of the yili basin in xinjiang province northwest china forty eight coal samples were collected from boreholes q12zk01 and z40zk1 and piliqing and musixiang coal mines the difference in base subsidence rate between the coal bearing strata badaowan and the xishanyao formations determines these differences of depositional environments swamp groundwater table and degree of terrigenous supply these factors may further cause the difference in coal quality the vitrinite contents ash yields volatile matter yields total mineral contents and most element contents are higher in coals of the badaowan formation from the q12zk01 and the musixiang mine than those of the xishanyao formation from the piliqing mine and the z40zk1 the high volatile matter yields of the coals in the badaowan formation relative to those in the xishanyao formation may be due to higher content of vitrinite that contains more volatile matters in comparison with the average concentrations for chinese and worldwide coals the yili coals are enriched mainly in ca na mg mn co sr ba and w but the other elements are depleted in the yili coals elements including si al k li ti cr cu rb zr pb and some ree la ce pr nd sm are predominantly associated with aluminosilicate minerals iron mg and mn in the coals of the musixiang mine and z40zk1 are associated mainly with carbonate minerals sulfur co and ni in the musixiang mine coals and b in the coals of q12zk01 and the z40zk1 mainly show an organic affinity sodium in the musixiang mine coals may occur in the brines

soil water movement and recharge through sand at a semiarid site in new mexico a semiarid site near socorro new mexico has been instrumented with tensiometers and a neutron probe access tube to study soil water movement which may contribute to areal groundwater recharge under natural conditions during the period of record which extends from november 1982 through may 1984 annual precipitation was approximately 17 9 cm yr 1 below a depth of about 30 cm pressure head ranged from about 129 to 35 cm and moisture content varied between about 0 05 to 0 09 cm3cm 3 the vertical hydraulic gradient was slightly greater than unity and indicated downward soil water movement unsaturated hydraulic conductivity was determined in the field by the instantaneous profile method recharge was calculated from darcy s equation using in situ pressure head data below the root zone calculated hydraulic gradient and in situ hydraulic conductivity recharge was also calculated as being equal to the unsaturated hydraulic conductivity corresponding to in situ water content both approaches indicate that the annual recharge rate may be as much as about 3 7 cm yr 1 or about 20 of mean annual precipitation during this period of record

deep arid system hydrodynamics 1 equilibrium states and response times in thick desert vadose zones 1 quantifying moisture fluxes through deep desert soils remains difficult because of the small magnitude of the fluxes and the lack of a comprehensive model to describe flow and transport through such dry material a particular challenge for such a model is reproducing both observed matric potential and chloride profiles we propose a conceptual model for flow in desert vadose zones that includes isothermal and nonisothermal vapor transport and the role of desert vegetation in supporting a net upward moisture flux below the root zone numerical simulations incorporating this conceptual model match typical matric potential and chloride profiles the modeling approach thereby reconciles the paradox between the recognized importance of plants upward driving forces and vapor flow processes in desert vadose zones and the inadequacy of the downward only liquid flow assumption of the conventional chloride mass balance approach our work shows that water transport in thick desert vadose zones at steady state is usually dominated by upward vapor flow and that long response times of the order of 104 105 years are required to equilibrate to existing arid surface conditions simulation results indicate that most thick desert vadose zones have been locked in slow drying transients that began in response to a climate shift and establishment of desert vegetation many thousands of years ago

variations in pore characteristics in high volatile bituminous coals implications for coal bed gas content abstract the seelyville coal member of the linton formation pennsylvanian in indiana was studied to 1 understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations 2 elaborate on the influence of mineral matter and maceral composition on mesopore and micropore characteristics and 3 discuss implications of these variations for coal bed gas content the coal is high volatile bituminous rank with r 0 ranging from 0 57 to 0 60 bet specific surface areas determined by nitrogen adsorption of the coals samples studied range from 1 8 to 22 9 m 2 g bjh adsorption mesopore volumes from 0 0041 to 0 0339 cm 3 g and micropore volumes determined by carbon dioxide adsorption from 0 0315 to 0 0540 cm 3 g the coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths whereas the smallest values for these two parameters occur in the deepest coals micropore volumes in contrast are not depth dependent in the coal samples examined for this study mineral matter content influenced both specific surface area as well as mesopore and micropore volumes it is especially clear in the case of micropores where an increase in mineral matter content parallels the decrease of micropore volume of the coal no obvious relationships were observed between the total vitrinite content and pore characteristics but after splitting vitrinite into individual macerals we see that collotelinite influences both meso and micropore volume positively whereas collodetrinite contributes to the reduction of mesopore and micropore volumes there are large variations in gas content within a single coal at a single location because of this variability the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation

preliminary research on cbm enrichment models of low rank coal and its geological controls a case study in the middle of the southern junggar basin nw china abstract to date prospecting work on low rank coalbed methane cbm resources in the middle of the southern junggar basin is still in the primary stage and only a few cbm exploration wells or pilot wells have been deployed in local regions systemic understanding of cbm reservoir forming conditions and geological controlling factors is lacking in the study area resulting in the mismatch between cbm well deployment and actual geological conditions as well as poor exploration efficiency in this paper the geological controlling effects of the structure sedimentation and hydrogeology on cbm enrichment are systematically discussed for the first time based on the early cbm exploration achievements the results show that the xishanyao coal and the badaowan coal are developed in the upper and lower part of the neutral surface of a fold respectively the reservoir forming conditions of the badaowan coal are not discussed in this paper due to its poor development the xishanyao coal that developed in the axial part of the syncline is most beneficial to cbm enrichment with concentrated extrusion stress and great methane adsorption capacity while the axial part of the anticline is not favorable for cbm preservation with large tensional stress the gas content of the xishanyao thick seams developed in the syncline is higher average of 4 63 6 34 m3 t than that in the monocline average of 2 84 4 56 m3 t reverse faulting is more beneficial to cbm enrichment than normal faulting due to the better sealing capability the gas content of the xishanyao coal is obviously influenced by the coal thickness and its roof lithology the hydrodynamic conditions and total dissolved solids tds values of coalbed water range greatly on regional scale which leads to a deeper methane weathering zone in the middle west areas 1119 62 m than the eastern liu huanggou areas

the effect of dispersion on the establishment of a paleoclimatic record from groundwater a mathematical model which can account for the dispersion of solute in underground water over time scales exceeding 104 yr is described in its simplest form the model postulates a diffusion limited exchange of material between flowing groundwater and the stationary water in the confining aquiclude leading to the spreading of the solute in the mobile water and a consequent reduction in its concentration variability the model is used to study the increasing attenuation with age of the perturbations in groundwater composition induced by paleoclimatic oscillations in the late quaternary specific reference is made to noble gas concentrations stable isotope ratios and chloride levels the extreme attenuation of stable isotope ratios in the australian great artesian basin cannot yet be adequately explained and may provide the basis of a critical evaluation of different dispersion models in large hydraulic basins

diagenetically enhanced bedding in argillaceous platform limestones stratified cementation and selective compaction a field and petrographic study has been made of 34 massive beds in argillaceous limestones of open marine platform facies in the u k lithologies include grainstones packstones wackestones and lime mudstones the rocks are of silurian carboniferous and jurassic ages additional information was obtained from other limestones in the u k the u s a canada and continental europe the beds are parts of sequences composed of couplets of strata fissile limestones alternating with hard limestones in the fissile limestones the effects of mechanical compaction and pressure dissolution have been concentrated whereas in the hard limestones they are minimal or absent bedding planes visible in outcrop are diagenetic in origin and lie in the middle parts of the fissile limestones where compaction has been most severe the features produced by pressure dissolution are dissolution seams and fitted fabric there are no stylolites the original carbonate sediments were bioturbated and any structures produced by flowing water were destroyed the vertical distribution of the bedding planes bears no relation to primary depositional bedding planes which are rare or absent it is inferred that the strata which were to become the hard limestones were selectively cemented before mechanical compaction had been completed thenceforth mechanical compaction and then pressure dissolution were concentrated in the less cemented strata these became the fissile limestones pressure dissolution acted late in the diagenetic history and provided only an insignificant part if any of the carbonate for cementation it is concluded that the orientation of beds couplets is parallel to successive sea floors and that the sediments that eventually became single beds accumulated synchronously similar couplets in platform limestones of the mississippian and pennsylvanian of the u s a extend over thousands of square kilometres the signal that controlled the initial selective cementation must have been widespread and synchronous and also syndepositional in its timing but otherwise cannot be further defined on the basis of the data so far collected the presumed order of events was 1 accumulation of carbonate sediment terrigenous clay and organic matter 2 hydrodynamic reworking and bioturbation the latter finally overprinting the former 3 selective cementation of the more carbonate rich strata yielding couplets each consisting of a relatively well cemented stratum and a poorly cemented stratum 4 mechanical compaction concentrated in the less cemented strata 5 pressure dissolution concentrated in the same strata

evaluation of spacing of stylolites and its implications for self organization of pressure dissolution abstract the self organization theory of stylolite development is one of the most prominent explanations of pressure dissolution phenomena its proponents cite uniform spacing of stylolites as evidence of self organization and its original authors concluded that a natural consequence of the theory is the development of sets of stylolites with roughly regular spacing spacing of stylolites is the only observable physical criterion by which self organized pressure dissolution can be differentiated from conventional pressure dissolution in ancient limestones quantitative analysis of spacing of stylolites in limestones shows however that spacing of stylolites is generally indistinguishable from random arrangement spacing of stylolites thus provides no support for the theory of self organization of pressure dissolution

a survey of the microbial populations in some australian coalbed methane reservoirs isotopic data indicate that coalbed methane cbm in many australian reservoirs comprise secondary biogenic gas however little is known of the microbes active in these reservoirs therefore for the first time in australia a preliminary culture independent survey of the prokaryotic microbial composition of some of these reservoirs was undertaken to provide a basis for an understanding of the origin of the observed biogenic gas four water and three coal samples from the east coast of australia were examined for their prokaryotic diversity by 16s rdna analysis dna was extracted from the samples and amplified using bacterial and archaeal selective primers and the resulting amplicons were cloned and sequenced dna amplicons derived from gram negative bacteria predominated relatively few archaeal and gram positive bacterial sequences were amplified from the original samples by and large coal samples yielded almost exclusively archaeal and proteobacterial amplicons whereas the water samples contained amplicons derived from the remaining proteobacteria e and bacteroidetes amplicons from three genera of archaea were observed none of which were genuine methanogens although the dominant genus archaeoglobus is reported to have some weak methanogenic activity further integrated studies of microbiology hydrochemistry gas geochemistry and geology of cbm reservoirs are continuing in order to better understand the parameters for methane production in eastern australian basins

observations and experiments on the origin and formation of inertinite group macerals the inertinite group macerals include fusinite semifusinite inertodetrinite macrinite micrinite and funginite and secretinite which together replace sclerotinite the macrolithotype fusain comprises fusinite and semifusinite and is now widely accepted as charcoal formed by wildfire activity however alternative origins for fusinite and semifusinite are still claimed this paper considers the use of the terms pyrofusinite degradofusinite rank fusinite and primary fusinite misleading while the definitions of the terms funginite and secretinite are also considered problematic observations made on modern wildfire derived and volcanogenic charcoal assemblages using reflectance and scanning electron microscopy together with experimental charcoalification studies demonstrate that most if not all inertinite macerals have acquired their optical and physical characteristics through the action of elevated temperatures the criteria for the identification of charcoals produced by wildfire and volcanic activity are outlined and the role of the petrographic nomenclature system is discussed

groundwater recharge and discharge dynamics in an arid zone ephemeral lake system australia the coongie lakes are a series of ephemeral freshwater lakes on the lower reaches of cooper creek a large intermittent river of the arid lake eyre basin australia hydrogeological chemical and isotopic observations in conjunction with numerical modeling of groundwater responses to lake inundation events have been used to identify the dominant processes linking shallow unconfined groundwater with the hydrology of the lakes during wet and dry periods the lakes are predominantly zones of net groundwater recharge during inundation events however soil profile data suggests that drying of some of these lakes allows evaporative groundwater discharge to occur through the soil profile of the dry lake beds resulting in salinization of the soil profile of the more ephemeral lakes the occurrence of young high salinity groundwater is best explained by variations in soil profile flushing in response to wet and dry interannual periods of river discharge during interannual drier phases when filling of previously dry lakes is more common recharge is mostly via macropore flow during the rising stage of the inundation increased salinization of the lake bed sediments occurs during longer dry periods due to transport of solutes to the near surface from lake bed evaporation and limited flushing of the soil profile because of the macropore dominated flow during recharge during wet periods recharge is more likely dominated by matrix flow that results in leaching of the soil profile and increased export of solutes into the alluvial aquifer

the role of trapped fluids during the development and deformation of a carbonate shale intra wedge tectonic melange mt massico southern apennines italy abstract numerous studies exist on exhumed tectonic melanges along subduction channels whereas in accretionary wedge interiors deformation mechanisms and related fluid circulation in tectonic melanges are still underexplored we combine structural and microstructural observations with geochemical stable and clumped isotopes and isotope composition of noble gases in fluid inclusions of calcite veins and u pb geochronological data to define deformation mechanisms and syn tectonic fluid circulation within the mt massico intra wedge tectonic melange located in the inner part of the central southern apennines accretionary wedge italy this melange developed by shear deformation at the base of a clastic succession deformation was characterized by disruption of the primary bedding mixing and deformation of relicts of competent olistoliths and strata within a weak matrix of deformed clayey and marly interbeds recurrent cycles of mutually overprinting fracturing veining and pressure solution processes generated a block in matrix texture the geochemical signatures of syntectonic calcite veins suggest calcite precipitation in a closed system from warm 108 147 c paleofluids with 18o vlaues between 9 and 14 such as trapped pore waters after extensive 18o exchange with the local limestone host rock and or derived by clay dehydration processes at t 120 c the 3he 4he ratios in fluid inclusions are lower than 0 1 ra indicating that he was exclusively sourced from the crust we conclude that 1 intraformational rheological contrasts inherited trapped fluids and low permeability barriers such as marly shaly matrix can promote the generation of intra wedge tectonic melanges and the development of transient fluid overpressure 2 clay rich tectonic melanges developed along intra wedge decollement layers may generate low permeability barriers hindering the fluid redistribution within accretionary wedges

recharge in karst and dune elements of a semi arid landscape as indicated by natural isotopes and chloride abstract the rates and mechanisms of local recharge in a semi arid environment have been investigated beneath two major landscape settings in the murray basin in south australia these were calcrete flats with sinkholes and sand dunes in adjacent landscape settings five minor settings were investigated and identified as undisturbed calcrete primary older sinkholes secondary younger sinkholes sand dunes with native vegetation and sand dunes with introduced pasture data from a limited series of boreholes were interpreted to suggest that recharge varied from in excess of 100 mm yr 1 for secondary sinkholes to less than 0 1 mm yr 1 beneath sand dunes with native vegetation the data suggest that recharge under sand dunes has increased by more than two orders of magnitude following clearing of the native vegetation 50 yr ago as 90 of an area of 10 000 km2 has been cleared this clearing has ensured that inflow of saline groundwater to the adjacent river murray will increase and in view of the amount of salt stored in both the unsaturated and saturated zones will continue for a very long time at sites where the inferred recharge is lowest profiles of the chloride concentration of soil water are consistent with the hypothesis that there is in excess of 50 000 yr recharge stored in the thick unsaturated zone some evidence for changes in recharge rate over this time scale is seen

regional groundwater flow paths in trans pecos texas inferred from oxygen hydrogen and strontium isotopes summary stable isotopes radiogenic isotopes and major ion chemistry are used to constrain flow paths in a fracture controlled regional groundwater flow system in far west texas the flow system occurs in permian and cretaceous sedimentary rocks and cenozoic alluvial basin fill samples from springs and wells in the study area were analyzed for major ions and hydrogen oxygen and strontium isotopes d and 18o values fall close to the global meteoric water line indicating that these values have not been significantly affected by evaporation or mineral water reactions 18o values from samples along the regional flow path are lower by as much as 3 relative to local recharge values the distribution of stable isotope values throughout the study area suggests that lower 18o values represent recharge during cooler climatic conditions rather than latitude or altitude effects 87sr 86sr values for water samples from along the regional flow path range from 0 7093 to 0 7148 with the highest values at the upgradient end of the flow system these values are significantly higher than expected for groundwaters dominated by dissolution of permian and cretaceous marine carbonates and evaporites the high 87sr 86sr values reflect dissolution of minerals of precambrian and early paleozoic origin in the crystalline rocks of the carrizo and baylor mountains and alluvial basin fill at the upgradient end of the flow system contours of 87sr 86sr values indicate a zone of high 87sr 86sr water that corresponds to the regional groundwater flow paths mass balance mixing models and mineral reactions models indicate a three end member mixing system modified by dissolution of strontium bearing minerals in the alluvial fill at the upgradient end of the flow system

a new stylolite classification scheme to estimate compaction and local permeability variations we modeled the geometrical roughening of bedding parallel mainly layer dominated stylolites in order to understand their structural evolution to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and permeability variations at stylolites stylolites are rough dissolution seams that develop in sedimentary basins during chemical compaction in the zechstein 2 carbonate units an important lean gas reservoir in the southern permian zechstein basin in germany stylolites influence local fluid flow mineral replacement reactions and hence the permeability of the reservoir our simulations demonstrate that layer dominated stylolites can grow in three distinct stages an initial slow nucleation phase a fast layer pinning phase and a final freezing phase if the layer is completely dissolved during growth dissolution of the pinning layer and thus destruction of the stylolite s compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise we present an advanced classification based on our simulations and separate stylolites into four classes 1 rectangular layer type 2 seismogram pinning type 3 suture sharp peak type and 4 simple wave like type rectangular layer type stylolites are the most appropriate for chemical compaction estimates because they grow linearly and record most of the actual compaction up to 40 mm in the zechstein example seismogram pinning type stylolites also provide good tracking capabilities with the largest teeth tracking most of the compaction suture sharp peak type stylolites grow in a non linear fashion and thus do not record most of the actual compaction however when a non linear growth law is used the compaction estimates are similar to those making use of the rectangular layer type stylolites simple wave like stylolites are not useful for compaction estimates since their growth is highly non linear with a very low growth exponent in the case where sealing material is collected at the tooth during dissolution stylolites can act as barriers for local fluid flow as they intensify sealing capabilities of pinning layers however the development of teeth and spikes offsets and thus destroys continuous stylolite seams so that the permeability across the stylolite becomes very heterogeneous and they are no continuous barriers this behavior is best shown in rectangular layer and seismogram pinning type stylolites that develop efficient fluid barriers at teeth tips but destroy sealing capabilities of layers by offsetting them at the flank leading to a permeability anisotropy along 2 d stylolite planes suture sharp peak stylolites can create fluid barriers if they collect enough sealing material however if the collecting material does not seal or if spikes offset the sealing material the stylolite leaks we propose that our classification can be used to realistically estimate chemical compaction in reservoirs and gives an indication on how heterogeneous the permeability of stylolites can be

experimental studies in natural groundwater recharge dynamics assessment of recent advances in instrumentation abstract to quantify and model the natural groundwater recharge process two sites in south central kansas u s a were instrumented with various modern sensors and data microloggers the atmospheric boundary layer and the unsaturated and saturated soil zones were monitored as a unified regime data from the various sensors were collected using microloggers in combination with magnetic cassette tape graphical and digital recorders analog paper tape recorders and direct observations to evaluate and automate data collection and processing atmospheric sensors included an anemometer a tipping bucket raingage an air temperature thermistor a relative humidity probe a net radiometer and a barometric pressure transducer sensors in the unsaturated zone consisted of soil temperature thermocouples tensiometers coupled with pressure transducers and dial gages gypsum blocks and a neutron moisture probe operated by an observer the saturated zone sensors consisted of a water level pressure transducer a conventional float gage connected to a variable potentiometer soil thermocouples and a number of multiple depth piezometers evaluation of the operation of these sensors and recorders indicated that certain types of equipment such as pressure transducers are very sensitive to environmental conditions extraordinary steps had to be taken to protect some of the equipment whereas other equipment seemed to be reliable under all conditions based on such experiences a number of suggestions aimed at improving such investigations are outlined

coal quality related to microfractures identified by ct image analysis abstract identification of microfractures developed in coal are indispensable to coal quality assessment and helpful to understanding the tectonic history x ray computed tomography ct scanning has promised to be one of the most powerful non destructive testing methods for these factors in this work we aimed to develop methods for identifying microfractures from ct images and to identify the relationship between these properties and coal quality lati coal mine in east kalimantan indonesia was selected as a case study area and fifteen samples were taken from three seams we developed a successful process of setting the samples in water to avoid cupping artifacts in the ct images and applied image processing to characterize fractures in detail ash content increased in proportion to the total length of microfractures correlations of ct values with coal quality such as the ash and caloric content cal g suggest that coal quality is inversely proportional to the ct values positive correlation was found between ash and the total number of microfracture widths which is interpreted to mean that the coal contained mineral impurities a source of ash in proportion to the development of microfractures because local structures control microfracture occurrence and microfracture development controls coal quality by allowing the infilling of mineral impurities local structures influence coal quality

lateral moisture flow beneath a sandy hillslope without an apparent impeding layer part of a small drainage basin on the sevilleta national wildlife refuge about 25 km north of socorro nm was intensively instrumented with soil monitoring equipment to estimate natural ground water recharge soil moisture data were analysed with special attention to characterizing the influence of topography on the direction of vadose water flow paths in fine to medium aeolian sand moisture content data were obtained by the neutron scattering technique and hydraulic head data were obtained using tensiometers in addition tracer experiments were conducted on a sandy hillslope to delineate the flow paths of vadose water the results indicate that there is a strong lateral component to unsaturated flow on a hillslope even in the absence of apparent sublayers of much lower permeability darcian calculations estimate the long term steady deep flux beneath a concave location to be about 4 per cent of an assumed mean annual precipitation of 20 cm the deep soil water flux downward varied by several orders of magnitude during the 17 month period of record

fingerprinting stress stylolite and calcite twinning paleopiezometry revealing the complexity of progressive stress patterns during folding the case of the monte nero anticline in the apennines italy in this study we show for the first time how quantitative stress estimates can be derived by combining calcite twinning and stylolite roughness stress fingerprinting techniques in a fold and thrust belt first we present a new method that gives access to stress inversion using tectonic stylolites without access to the stylolite surface and compare results with calcite twin inversion second we use our new approach to present a high resolution deformation and stress history that affected meso cenozoic limestone strata in the monte nero anticline during its late miocene pliocene growth in the umbria marche arcuate ridge northern apennines italy in this area an extensive stylolite joint vein network developed during layer parallel shortening lps as well as during and after folding stress fingerprinting illustrates how stress in the sedimentary strata did build up prior to folding during lps the stress regime oscillated between strike slip and compressional during lps before ultimately becoming strike slip again during late stage fold tightening our case study shows that high resolution stress fingerprinting is possible and that this novel method can be used to unravel temporal relationships that relate to local variations of regional orogenic stresses beyond regional implications this study validates our approach as a new powerful toolbox to high resolution stress fingerprinting in basins and orogens combining joint and vein analysis with sedimentary and tectonic stylolite and calcite twin inversion techniques

architecture and evolution of an extensionally inverted thrust mt tancia thrust central apennines geological structural geochemical and k ar geochronological constraints abstract fault inversion may lead to significant obliteration of earlier tectonic structures thus preventing the straightforward interpretation of the complete kinematics and deformation history of faults we adopt a multidisciplinary approach to 1 reconstruct the tectonic evolution through space and in time of the extensionally inverted mt tancia thrust central apennines italy 2 understand the deformation mechanisms and the transition and reactivation of compressional structures during negative tectonic inversion and 3 constrain the origin of fluids involved during tectonic processes to this end we combined 1 detailed geological mapping and multiscale structural analysis 2 illite smectite paleothermal indicators 3 c o and clumped isotopes on calcite mineralizations and 4 k ar dating of authigenic and or syn kinematic illite from the mt tancia thrust fault rocks we show that shortening occurred between 9 and 7 ma during possibly multiple events of fluid overpressure and shear rupturing involving fluids entrapped over long term within the host rocks post compressive tectonic inversion occurred at 3 ma under fluid pressure fluctuations during shear events with an input of meteoric derived fluids tectonic inversion is spatially confined within the first few metres below the thrust surface in a volume dominated by the partial overprinting folding transposition and re utilization of the earlier compressional fabric

fractal characteristics of upper cretaceous lacustrine shale from the songliao basin ne china abstract to improve our understanding of the characteristics of nanopores and their influence on liquid hydrocarbon occurrences in lacustrine shale we carried out fractal analysis on 21 lacustrine shale cores from the upper cretaceous qingshankou formation k2qn in the songliao basin ne northeast china using toc total organic carbon and rock eval analysis xrd x ray diffraction low pressure nitrogen adsorption experiments and the fhh frenkel halsey hill method the relationships between composition of lacustrine shale toc minerals oil content the pore structure parameters bet surface area pore volume pore average diameter and the fractal dimensions were investigated two fractal dimensions d1 and d2 at relative pressures of 0 5 1 and 0 0 5 respectively were obtained with d1 ranging from 2 5055 to 2 8888 and d2 between 2 1026 and 2 733 d1 is greater than d2 indicating that small pores are more homogeneous than larger pores both d1 and d2 increase with increasing bet surface areas and total pore volumes and increase with decreasing average pore diameters the fractal dimensions of lacustrine shale are negatively correlated with the clay content but show no obvious relationship with the quartz content the relationship between fractal dimensions both d1 and d2 and toc content is a u shaped curve with minimum d values at 2 5 3 wt toc fractal dimension d1 can be used to characterize the shale oil content and lacustrine shale samples with a lower fractal dimension have greater free oil therefore considering the influence of toc content on fractal dimension and the relationship between oil content and fractal dimension we conclude that lacustrine shale in the oil generation stage with 2 5 3 0 wt toc is probably the preferred shale oil exploration target in the songliao basin the results indicate that fractal analysis leads to a better understanding of the pore structure and oil storage capacity of lacustrine shale

water movement through a thick unsaturated zone underlying an intermittent stream in the western mojave desert southern california usa previous studies indicated that small amounts of recharge occur as infiltration of intermittent streamflow in washes in the upper mojave river basin in the western mojave desert near victorville california these washes flow only a few days each year after large storms to reach the water table water must pass through an unsaturated zone that is more than 130 m thick results of this study done in 1994 1998 show that infiltration to depths below the root zone did not occur at control sites away from the wash at these sites volumetric water contents were as low as 0 01 and water potentials measured as the combination of solute and matric potentials using a water activity meter were as negative as 14 000 kpa water vapor movement was controlled by highly negative solute potentials associated with the accumulation of soluble salts in the unsaturated zone highly negative matric potentials above and below the zone of maximum solute accumulation result from movement of water vapor toward the highly negative solute potentials at that depth the 18o and d delta oxygen 18 and delta deuterium isotopic composition of water in coarse grained deposits plots along a rayleigh distillation line consistent with removal of water in coarse grained layers by vapor transport beneath oro grande wash water moved to depths below the root zone and presumably to the water table about 130 m below land surface underneath oro grande wash volumetric water contents were as high as 0 27 and water potentials measured as matric potential using tensiometers were between 1 8 and 50 kpa on the basis of tritium data water requires at least 180 260 years to infiltrate to the water table clay layers impede the downward movement of water seasonal changes in water vapor composition underneath the wash are consistent with the rapid infiltration of a small quantity of water to great depths and subsequent equilibration of vapor with water in the surrounding material it may be possible to supplement natural recharge from the wash with imported water recharge to the wash may be advantageous because the unsaturated zone is not as dry as most areas in the desert and concentrations of soluble salts are generally lower underneath the wash

geochemical estimates of paleorecharge in the pasco basin evaluation of the chloride mass balance technique the pasco basin in southeastern washington state provides a unique hydrogeologic setting for evaluating the chloride mass balance technique for estimating recharge this basin was affected by late pleistocene catastrophic floods when glacial dams in western montana and northern idaho were breached it is estimated that multiple missoula floods occurred between 13 000 and 15 000 years b p and reached a high water elevation of 350 m these floods removed accumulated chloride from the sediment profile effectively resetting the chloride mass balance clock at the beginning of the holocene the rate of chloride accumulation qcl in the sediments was determined by two methods and compared the first method measured qcl by dividing the calculated natural fallout of 36cl by a measured ratio of 36cl cl in the pore water while the second method used the total mass of chloride in the profile divided by the length of time that atmospheric chloride had accumulated since the last flood although the two methods are based on different approaches they showed close agreement in laboratory studies the sediment to water ratio for chloride extraction was sensitive to the grain size of the sediments low extraction ratios in silt loam sediments led to significant underestimation of pore water chloride concentration br cl ratios were useful for distinguishing nonatmospheric e g rock sources of chloride field studies showed little spatial variability in estimated recharge at a given site within the basin but showed significant topographic control on recharge rates in this semiarid environment an extension of the conventional chloride mass balance model was used to evaluate chloride profiles under transient time varying annual precipitation conditions this model was inverted to determine the paleorecharge history for a given soil chloride profile and the parameters of the root extraction model required to estimate paleoprecipitation

quantitative analysis of stylolite networks in different platform carbonate facies abstract stylolites are rough surfaces that form by pressure solution and present variable geometries and spatial distributions despite being ubiquitous in carbonate rocks and potentially influencing fluid flow it is not yet clear how the type and distribution of stylolite networks relate to lithofacies this study investigates lower cretaceous platform carbonates in the benicassim area maestrat basin spain to statistically characterise stylolite morphology and stylolite network distributions in a selection of typical shallow marine carbonate lithofacies from mudstones to grainstones bedding parallel stylolite networks were sampled in the field to quantify stylolite spacing wavelength amplitude intersection morphology and connectivity grain size sorting and composition were found to be the key lithological variables responsible for the development of rough anastomosing stylolite networks poorly connected stylolites with large vertical spacings were found to be dominant in grain supported lithofacies where grains are fine and well sorted anastomosing stylolite networks appear well developed in mud supported lithofacies with poorly sorted clasts that are both heterogenous in size and composition mud supported facies feature stylolites that are closely spaced have high amplitudes and intersection densities and predominantly present suture and sharp peak type morphologies larger grains and poor sorting favour the formation of stylolites with small vertical spacings low wavelengths and high amplitudes this statistical analysis approach requires only limited information such as that from drill core and can be used to characterise stylolite morphology and distributions in subsurface carbonate reservoirs

sources of chloride and implications for 36cl dating of old groundwater southwestern great artesian basin australia we investigate the relative importance of a number of processes that affect cl and 36cl distribution in the southwestern flow systems of the great artesian basin australia to provide more precise estimates of age and flow and recharge rates in situ production of 36cl secular variations in the rate of production of 36cl and its subsequent fallout as well as rates of diffusion of stable cl from adjacent aquitards mask the interpretation of rates of decay of 36cl cl along hydraulic gradients and can preclude estimating absolute groundwater ages however mean flow velocities calculated from absolute cl concentrations are 0 24 0 03 m yr and are a more reliable parameter than calculated ages because fewer assumptions and approximations are required recharge rates to the main cadna owie formation and algebuckina sandstone aquifer of the great artesian basin estimated from cl mass balance in the unconfined aquifers are 0 16 0 08 mm yr and were probably up to a factor of 3 higher 30 kyr ago as indicated by decreasing cl and 18o concentrations along the head gradient

estimation of natural groundwater recharge in the karoo aquifers of south africa abstract a 3 year project to study the natural groundwater recharge of aquifers in the semi arid karoo formations of south africa was undertaken two typical karoo aquifers at dewetsdorp and de aar were selected for study purposes data were collected from both the saturated and unsaturated zone neutron probe measurements showed that there was no increase in the water content beneath a depth of 1m below the surface even with the exceptionally high rainfall in february 1988 neutron measurements indicated that very little soil matrix flow occurred which implied that most of the recharge occurred along preferred pathways a triangular finite element network was used to determine the relative saturated volume fluctuations svf of the aquifers from the observed water level changes over a period of time which allowed determination of the storativity s and the recharge the main advantage of the method lies in determining recharge and storativity which are both unknowns in the water balance equation and which both contribute to the water level response the svf method showed that the recharge in the karoo formations of south africa varies between 2 and 5 of the annual rainfall in areas which are overlain by a thick soil cover the recharge is less than 3 while recharge in hilly areas with a thin soil cover may be of the order of 5

elemental and nd sr isotopic geochemistry of granitoids from the west junggar foldbelt nw china with implications for phanerozoic continental growth we report elemental and nd sr isotopic data for two coeval postcollisional magmatic suites 300 ma the miaogou and karamay suites from west junggar foldbelt nw china aiming to determine their source regions and implications for continental growth the miaogou rocks monzonitic to granitic in composition show low mg 0 30 and depletion of hfse and are highly depleted in isotopic compositions with isr ranging from 0 7035 to 0 7045 end 300 ma from 8 4 to 6 6 and young nd model ages 0 37 0 70 ga that coincide with the ages of the ophiolites in the area these features suggest that the miaogou rocks were derived essentially by partial melting of a juvenile basaltic lower crust formed in the early to middle palaeozoic the karamay suite contains a variety of rock types from gabbroic diorite to granite these rocks show enrichment of lree and lile and depletion of hfse and have chemical composition e g mg 0 63 0 41 rather different from the miaogou suite though isotopically they are indistinguishable this suggests that the parental magma of the karamay suite originated from melting of a young lithospheric mantle that had previously been metasomatized during the palaeozoic subduction the west junggar magmatic rocks represent production of juvenile continental crust in the phanerozoic triggered by upwelling of asthenophere in an extensional regime the basement beneath the area is dominated by trapped palaeozoic arc series and oceanic crust

coupling fracture facies with in situ permeability measurements to generate stochastic simulations of tight carbonate aquifer properties example from the lower cretaceous aquifer northern provence se france summary the relationships between fracture facies and permeability distribution have been explored using a well constrained 3d implicit structural model of hemipelagic low porosity low permeability carbonate from the northern provence region se france fracture and permeability facies were determined using an extensive dataset of 99 hydrogeological wells data processing was undertaken using a step by step approach involving i identification of the fracture facies based on well logs detailing structure and stratigraphy ii determination of permeability facies from the a priori correlation between the dimension of the hydraulic radius of influence deduced from slug test analyses and the type of reservoir heterogeneity fissure fracture fault zone etc iii three dimensional plot of fracture and permeability facies in the geological model using a variographic analysis of data thirty three sequential indicator simulations sis based on geostatistic analyses were realised on both fracture and permeability facies finally a connectivity algorithm was developed to compute the probability of connection between selected infiltration areas and the major aquifer springs via moderate to high permeability geological bodies key results are i fault zones have a greater role in controlling permeability facies distribution than on fracture facies repartition ii there is little correlation between permeability and fracture facies distributions iii connectivity results highlight the compartmentalisation of aquifers in the cadarache area the extensions of permeable geological bodies being limited by the n130 faults

the upper jurassic lower cretaceous alluvial fan deposits of the kalaza formation central asia tectonic pulse or increased aridity the topographical evolution of tectonic systems as well as the sedimentation pattern and depositional environments in the associated basins are controlled by both tectonics and climate in the region of the tien shan central asia the jurassic lower cretaceous period was marked by complex low intensity tectonic deformation and major climate changes from humid to arid conditions jurassic to semi arid conditions cretaceous using the sediment record in the junggar tarim and fergana basins to describe the tectonic evolution of the tien shan area during the mesozoic thus requires differentiation between the tectonic and climatic influences on sedimentation the conglomerates of the upper jurassic lower cretaceous kalaza formation were commonly associated with renewed tectonic activity resulting from the docking of the lhasa block along the southern margin of asia from sedimentology and sequence stratigraphy analyses of several sections in the junggar tarim and fergana basins we reassess the main factors controlling the deposition of this formation we show that while some tectonic activity persisted throughout the jurassic cretaceous transition the switch from the sandy deposits of the upper jurassic qigu formation to the coarse deposits of the kalaza formation is largely linked to the development of an arid climate

influence of irrigation practices on arsenic mobilization evidence from isotope composition and cl br ratios in groundwater from datong basin northern china environment isotopes 18o and 2h and cl br ratios in groundwater have been used to trace groundwater recharge and geochemical processes for arsenic contamination in datong basin the arsenic concentrations of groundwater samples ranged from 0 4 to 434 9 g l with the average of 51 2 g l which exceeded china s drinking water standard 10 g l all the groundwater samples are plotted on or close to the meteoric water line of the 18o vs 2h plot indicating their meteoric origin the relationship between 18o values and cl br ratios and cl concentrations demonstrate that leaching and mixing are the dominant processes affecting the distribution of high arsenic groundwater in this area the observed non linearity in the trend between 18o and arsenic concentration is due to combined effects of mixing and leaching the similarity of the trend in cl br ratios and 18o values for high arsenic groundwater demonstrate that extensive leaching of irrigation return and salt flushing water flow could be the dominant process driving arsenic mobilization in the groundwater system moreover the long term irrigation practice can cause the drastic change of the biogeochemical and redox condition of in the aquifer system which in turn promotes the mobilization of arsenic therefore groundwater pumping for irrigation in this area of waterborne endemic arsenic poisoning should be under strict control to protect groundwater quality in this area

experimental studies in natural groundwater recharge dynamics the analysis of observed recharge events abstract the amounts and time distribution of groundwater recharge from precipitation over an approximately 19 month period were investigated at two instrumented sites in south central kansas precipitation and evapotranspiration sequences soil moisture profiles and storage changes water fluxes in the unsaturated zone and hydraulic gradients in the saturated zone at various depths soil temperatures water table hydrographs and water level changes in nearby wells clearly depict the recharge process antecedent moisture conditions and the thickness and nature of the unsaturated zone were found to be the major factors affecting recharge although the two instrumented sites are located in sand dune environments in areas characterized by shallow water table and subhumid continental climate a significant difference was observed in the estimated effective recharge the estimates ranged from less than 2 5 to approximately 154 mm at the two sites from february to june 1983 the main reasons for this large difference in recharge estimates were the greater thickness of the unsaturated zone and the lower moisture content in that zone resulting from lower precipitation and higher potential evapotranspiration for one of the sites effective recharge took place only during late winter and spring no summer or fall recharge was observed at either site during the observation period of this study

the influence of rock heterogeneity on the scaling properties of simulated and natural stylolites abstract stylolites are among the most prominent deformation patterns in sedimentary rocks that document localized pressure solution recent studies revealed that stylolite roughness is characterized by two distinct scaling regimes the main goal of the present study is to decipher whether this complex scaling behavior of stylolites is caused by the composition of the host rock i e heterogeneities in the material or is governed by inherent processes on respective scales namely the transition from a surface energy to an elastic energy dominated regime as theoretically predicted for this purpose we have developed a discrete numerical technique based on a lattice spring model to simulate the competition between stress strain and dissolution during stylolite roughening we varied systematically the quenched noise initially present in the material which controls the roughening we also changed the size amount and dissolution rate of the heterogeneities introduced in our model and evaluated the influence on the scaling exponents our findings demonstrate that the roughness and growth exponents are independent of the exact nature of the heterogeneities we discovered two coinciding crossover phenomena in space and time that separate length and time scales for which the roughening process is either balanced by surface or elastic energies our observations are consistent with analytical predictions and with investigations quantifying the scaling laws in the morphology of natural stylolites the findings presented here can further be used to refine volume loss compaction estimates from the finite strain pattern of stylolites

water recharge and solute transport through the vadose zone of fractured chalk under desert conditions this study focuses on water flow and solute migration through unsaturated fractured chalk in an arid area the chalk underlies a major industrial complex in the northern negev desert where groundwater contamination has been observed four dry drilling holes were bored through the vadose zone core and auger samples collected at 30 to 50 cm intervals were used for chemical and isotopic analyses enabling the construction of the following profiles 1 a tritium profile to estimate the rate of water flow through the unsaturated zone 2 oxygen 18 and deuterium profiles to assess the evaporation of water at land surface before percolation and in the upper part of the vadose zone after infiltration and 3 chloride and bromide profiles as tracers for inert solutes and pollutants the tritium and bromide profiles showed the rate of infiltration through the unsaturated matrix to be very slow 1 6 11 cm yr the chemical and isotopic data from the core holes suggested that the pore water changes characteristics with depth close to land surface the pore water is strongly evaporated 18o 5 94 and highly concentrated 29 meq cl 100 g rock but changes gradually with depth to amore dilute concentration 4 meq cl 100 g rock and isotopically depleted composition 18o 4 4 closer to the isotopic composition of precipitation and groundwater nearby monitoring wells have shown anthropogenic contribution of heavy metals organic compounds and tritium nativ and nissim 1992 a conceptual model is proposed in which a small portion of the rainwater percolates downward through the matrix while a larger percentage of the percolating water moves through preferential pathways in fractures the water flowing through the fractures penetrates the matrix across the fracture walls where it increases the tritium concentrations depletes the stable isotopic composition and dilutes the salt concentrations the observed rapid downward migration of tritium and heavy metals through the profuse fractures makes the chalk inefficient as a hydrologic barrier

stylolites as open fluid conduits abstract stylolites have hitherto been regarded as a direct result of dissolution in response to stresses applied during compaction zones of cementation and dolomitization and in some rocks associated internal sediments indicate that they were pathways to fluid flow yet clay residues and impermeable zones suggest that they are now less able to transmit fluids it is proposed that some stylolites represent former open fluid pathways developed in an over pressured system and that the familiar morphologies were only imposed during compaction as formation pore water pressures declined

bedding parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins application to middle jurassic carbonate reservoirs in the paris basin france in recent years stylolites which are rough dissolution surfaces commonly found in carbonates have been used for paleopiezometry estimates the stylolite roughness inversion technique srit applied on sedimentary bedding parallel stylolites bps grants access to the maximum principal vertical stress experienced by the host carbonates and thus to their maximum burial paleo depth this study reports the results of srit applied to a bps population hosted in carbonate platform reservoirs of the paris basin sub surface france middle jurassic carbonates from two well cores from the depocenter and margin of the basin for which the burial and thermal history are known based on a thermally calibrated 3 d basin model were analyzed by defining a consistency criterion and using two signal treatment methods we propose a new approach to select which bps can be reliably used to reconstruct the maximum vertical stress undergone by the host carbonates which then can be converted into maximum burial depth the study of a bps population shows that there is a control operated by the host rock texture and the stylolite morphology on the burial depth recorded especially suture and sharp peak bps are better suited to estimate the real maximum depth whereas seismogram pinning bps record preferentially intermediate depths median values of maximum depth derived from our data set 1300 and 1650 m for the margin and depocenter cores respectively are in line with maximum burial estimates provided by conventional basin modeling 1450 and 1800 m respectively thus showing that srit is a standalone robust depth gauge in sedimentary basins provided sample selection and data treatment are carried out in a rigorous and thoughtful manner

paleoenvironments and paleogeography of the lower and lower middle jurassic coal measures in the turpan hami oil prone coal basin northwestern china detailed facies and paleogeographical analyses of extensive borehole and outcrop data from lower and lower middle jurassic oil prone coal bearing sequences in the turpan hami oil producing basin of northwest china have led to the reconstruction of a basinwide depositional model a total of 20 distinct lithofacies have been identified and grouped into braided fluvial plain meandering fluvial plain braided delta meandering channel delta and lacustrine depositional systems coal forming swamps occur in each depositional system but the preferred sites of accumulation are interdelta bay and lower delta plain environments in the braided delta and meandering channel depositional systems and it is in these sites that major oil prone source rocks are located a series of age specific basinwide paleogeographical maps have been constructed leading to a depositional model for the basin results indicate that the basin experienced cyclic flooding to produce swamps and lakes and that these characterize the deposition of the lower and lower middle jurassic coal measures analyses indicate that both the bogda and harlik mountains were uplifted prior to the early jurassic and a lake separated the two mountain regions during the early and early middle jurassic from these results it is interpreted that major oil prone coal sequences are to be found in the western part of the taibei depression of the basin and thus the full economic potential of the basin has yet to be fully realized

growth of stylolite teeth patterns depending on normal stress and finite compaction abstract stylolites are spectacular rough dissolution surfaces that are found in many rock types they are formed during a slow irreversible deformation in sedimentary rocks and therefore participate to the dissipation of tectonic stresses in the earth s upper crust despite many studies their genesis is still debated particularly the time scales of their formation and the relationship between this time and their morphology we developed a new discrete simulation technique to explore the dynamic growth of the stylolite roughness starting from an initially flat dissolution surface we demonstrate that the typical steep stylolite teeth geometry can accurately be modelled and reproduce natural patterns the growth of the roughness takes place in two successive time regimes i an initial non linear increase in roughness amplitude that follows a power law in time up to ii a critical time where the roughness amplitude saturates and stays constant we also find two different spatial scaling regimes at small spatial scales surface energy is dominant and the growth of the roughness amplitude follows a power law in time with an exponent of 0 5 and reaches an early saturation conversely at large spatial scales elastic energy is dominant and the growth follows a power law in time with an exponent of 0 8 in this elastic regime the roughness does not saturate within the given simulation time our findings show that a stylolite s roughness amplitude only captures a very small part of the actual compaction that a rock experienced moreover the memory of the compaction history may be lost once the roughness growth saturates we also show that the stylolite teeth geometry tracks the main compressive stress direction if we rotate the external main compressive stress direction the teeth are always tracking the new direction finally we present a model that explains why teeth geometries form and grow non linearly with time why they are relatively stable and why their geometry is strongly deterministic while their location is random

porosity gain and loss in unconventional reservoirs example of rock typing in lower cretaceous hemipelagic limestones se france provence abstract we characterize porosity evolution in hemipelagic limestones of the lower cretaceous vocontian basin northern provence se france which are surface analogs for deep unconventional reservoirs firstly a structural and sedimentologic analysis was conducted on outcrops and on borehole cores of berriasian to lower valanginian rocks secondly 330 plugs were analyzed for facies pore typing porosity and acoustic vp velocity measurements this petrophysical dataset was compared to the burial uplift history of the host rock hemipelagic carbonates include four sedimentary formations comprising nine facies splitted into mud and grain dominated formations which display 0 8 porosity range depending on the initial grain to mud ratio of the sediments and on basin stress regime evolution during burial uplift history initial porosity was better preserved in grain dominated formations where early micritic cements built bridges between grains generating a solid skeleton that prevented inhibited the burial compaction effects in mud dominated facies micrite was initially diffuse within the rock matrix but was progressively rearranged under burial stress while the generation of an extensive amount of stylolites occurred the differential response of compacted grain and mud dominated facies to a late regional 1 km uplift resulted in large porosity generation should range from 15 to 35 localized in the mud dominated facies through the dilatancy of stylolite and pressure solution seams this study highlights how important is the combination of classical approaches including facies pore type and diagenesis characterization with the structural analyses one key result applicable to several types of unconventional reservoirs is the effective porosity generated by reactivation of compaction structures

comparison of water table fluctuation and chloride mass balance methods for recharge estimation in a tropical rainforest climate a case study from kelantan river catchment malaysia estimated groundwater recharge for selected locations in northeast peninsular malaysia north kelantan river catchment was determined using the water table fluctuation wtf and chloride mass balance cmb methods the wtf method recharge estimates were compared to the cmb method estimates to see if results are similar and the methods can be applied in a humid tropical region such as malaysia effective specific yields of 0 18 and 0 16 were obtained for sites which are much lower than values in the literature for use with the wtf method the wtf gives mean recharge values of 447 and 319 mm year at pc61 and wakaf bharu wb respectively the difference between sites may be attributed to the difference in lithology whereby less water table fluctuation is observed for finer grained lower permeability soil or sediment and higher water table fluctuation observed for more granular larger grain soil or sediment for the site with lower permeability the time lag between the storm events and water level rise in a well is longer and water does not reach the water table for small storms recharge from chloride profile study was estimated through measurement of enrichment of chloride concentration in soil rain fed groundwater direct recharge ranged from 263 3 to 627 7 mm year in wb and averaged 691 8 mm year for pengkalan chepa recharge estimates from unsaturated zone chloride strongly correlate with soil texture generally and is greater in the coastal area due to a higher percentage of sand content parts of the study area located toward the interior of the peninsula showed lower recharge due to the presence of fine grained sediment comparison of methods from different sites indicates that lithologic setting has a significant role in controlling natural recharge rate the inconsistency observed between recharge value estimated by the wtf and cmb method may in part be due to adsorption desorption process and ion exchange in the unsaturated soil which affects the initial assumption that chloride is a conservative tracer

analysis on correlation between nanopores and coal compositions during thermal maturation process abstract the evaluation of nanopore that links to methane accumulation space and migration channel is vital for coalbed methane development and underground gas drainage this work aims to uncover the evolution of coal compositions and nanopores with thermal maturation and to evaluate quantitatively the influencing degrees of coal compositions on pore structure parameters based on gray correlation analysis using 498 coal samples from different countries covering a very wide and continuous thermal maturation range ro 0 22 5 18 and representing commercially valuable coal seams typical coal basins and coalfields and cbm development sweet spots as thermal maturation increases pore structure parameters and coal compositions changes regularly as thermal maturation increases pv n2 ssa n2 show a rough w shaped trendency with left steepness and right slowness while fractal dimensiosshow a rough u shaped trend with left steepness and right slowness apd n2 present an approximate m shaped trend pv co2 and ssa co2 both present an asymmetrical v shaped tendency with a minimum value at ro between 1 0 and 1 3 concerning coal compositions with progressive thermal maturation there are the l shaped evolution of moisture the increasing envelope line of vitrinite and the decreasing envelope lines of inertinite exinite and minerals with the same trend of first steepness and then slowness in essence the alteration of pore structure parameters is closely linked to the evolution of coal compositions fractal dimensions are controlled by coal macerals while inorganic compositions like moisture and minerals have a significant impact on pv n2 and ssa n2 within whole thermal maturation process

infiltration from an impoundment for coal bed natural gas powder river basin wyoming evolution of water and sediment chemistry 1 development of coal bed natural gas cbng in the powder river basin wyoming has increased substantially in recent years among environmental concerns associated with this development is the fate of groundwater removed with the gas a preferred water management option is storage in surface impoundments as of january 2007 permits for more than 4000 impoundments had been issued within wyoming a study was conducted on changes in water and sediment chemistry as water from an impoundment infiltrated the subsurface sediment cores were collected prior to operation of the impoundment and after its closure and reclamation suction lysimeters were used to collect water samples from beneath the impoundment large amounts of chloride 12 300 kg and nitrate 13 500 kg as n most of which accumulated naturally in the sediments over thousands of years were released into groundwater by infiltrating water nitrate was more readily flushed from the sediments than chloride if sediments at other impoundment locations contain similar amounts of chloride and nitrate impoundments already permitted could release over 48 106 kg of chloride and 52 106 kg of nitrate into groundwater in the basin a solute plume with total dissolved solid tds concentrations at times exceeding 100 000 mg l was created in the subsurface tds concentrations in the plume were substantially greater than those in the cbng water about 2300 mg l and in the ambient shallow groundwater about 8000 mg l sulfate sodium and magnesium are the dominant ions in the plume the elevated concentrations are attributed to cation exchange enhanced gypsum dissolution as gypsum dissolves calcium goes into solution and is exchanged for sodium and magnesium on clays removal of calcium from solution allows further gypsum dissolution

decoupling of solutes and water in regional groundwater systems the murray basin australia documenting the origins residence times and movement of groundwater and the solutes that it contains is critical to understanding hydrogeological systems this study uses cl mass balance to determine the cl accession time i e the time required for cl to accumulate and cl to estimate the residence times of cl in the victorian portion of the murray basin southeast australia much of the murray basin contains saline groundwater with total dissolved solids tds concentrations commonly 14 000 mg l and locally up to 300 000 mg l the total mass of cl stored in the victorian portion of the basin is estimated as between 12 400 and 47 100 mt using present day rainfall totals and cl concentrations in rainfall the cl accession time is 170 to 650 ka aquifer thicknesses and groundwater salinity both increase westwards in this part of the murray basin consequently the cl accession times increase westward from 0 1 0 6 ka to 286 1080 ka by contrast c activities of the majority of the groundwater are 2 pmc and commonly much higher notwithstanding the difficulty in correcting c residence times the widespread occurrence of groundwater with above background c activities implies that groundwater residence times are generally 30 ka which is substantially shorter than the cl accession times rcl the ratio of cl to total cl 10 values of the groundwater are between 20 and 230 and are uncorrelated with cl concentrations while it is difficult to determine precise cl residence times the observation that the rcl values are significantly higher than those that represent secular equilibrium with the aquifer matrix rcl of 5 to 10 indicates that they are up to a few hundred thousand years and similar to the cl accession times the rcl values together with the geology of the aquifers stable isotope ratios and major ion geochemistry precludes halite dissolution incorporation of connate water or the long term diffusion of cl from clays as mechanisms of producing the elevated cl concentrations rather it is most likely that the high cl concentrations result from recycling of solutes in saline lakes and playas or repeated cycles of evapotranspiration in the unsaturated zone

chloride hydrochemical and isotope methods of groundwater recharge estimation in eastern mediterranean areas a case study in jordan jordan is classified as an arid to semi arid country with a population according to 1999 estimates of 4 8 millions inhabitants and a growth rate of 3 4 efficient use of jordan s scarce water is becoming increasingly important as the urban population grows this study was carried out within the framework of the joint european research project groundwater recharge in the eastern mediterranean and describes a combined methodology for groundwater recharge estimation in jordan the chloride method as well as isotopic and hydrochemical approaches recharge estimations using the chloride method range from 14 mm year 1 mean annual precipitation of 500 mm for a shallow and stony soil to values of 3 7 mm year 1 for a thick desert soil mean annual precipitation of 100 mm and values of well below 1 mm year 1 for thick alluvial deposits mean annual rainfall of 250 mm isotopically most of the groundwater in the hammad basin east jordan falls below the global meteoric water line and far away from the mediterranean meteoric water line suggesting that the waters are ancient and were recharged in a climate different than mediterranean tritium levels in the groundwater of the hammad basin are less than the detection limit 1 3 tu however three samples in east hammad where the aquifer is unconfined present tritium values between 1 and 4 tu copyright 2007 john wiley sons ltd

a reactive transport model of neptunium migration from the potential repository at yucca mountain abstract characterization and performance assessment studies for the potential high level nuclear waste repository at yucca mountain have identified 2 3 7 np as a radionuclide of concern for the proposed repository to predict the migration of neptunium after a repository breach an understanding of the relevant hydrologic and geochemical processes is required the hydrologic flow in the unsaturated zone at yucca mountain is dependent on the infiltration rate the stratigraphy of the vadose zone and the heat generated by the decaying radioactive waste the geochemical processes that strongly affect 2 3 7 np migration include solubility limited release of 2 3 7 np from the near field environment aqueous speciation of neptunium into non sorbing carbonate hydroxy complexes and the sorbing npo 2 cation sorption of neptunium onto the zeolitic tuffs via an ion exchange mechanism and radioactive decay the finite element heat and mass transfer fehm code was used to investigate the coupled effects of chemical interactions and heat on neptunium transport from the potential repository to the water table the selective coupling method is introduced to solve these reactive transport problems the simulations indicate that in the absence of irreversible changes in the hydrologic and transport properties the heat pulse does not significantly affect the migration of neptunium as the time scale of heat pulse propagation is shorter than the time scales associated with neptunium release and migration water chemistry particularly ph calcium and sodium concentration significantly affect the retardation of neptunium by the zeolitic rocks between the repository and the water table

diagenetic implications of stylolitization in pelagic carbonates canterbury basin offshore new zealand abstract stylolites are irregular discontinuity surfaces that are thought to result from localized stress induced dissolution during burial or tectonic compression the genesis of stylolites and the controls on stylolitization are still debated and the interplay between stylolitization generation of carbonate rich fluids diagenetic fluid flow within fractures and matrix cementation and porosity modifications is complex all of these processes have important diagenetic effects potentially altering the intrinsic properties of the host rock with implications for hydrocarbon exploration and water resources in aquifers we investigate the process of stylolitization by a macroscopic petrographic and geochemical study of pressure solution features in eocene to early oligocene limestones in cores from the integrated ocean drilling program iodp hole 317 u1352c canterbury basin the results indicate correlations among stylolite amplitude stylolite density and siliciclastic content of the host rock these relationships are interpreted to suggest that siliciclastic content in carbonate rocks increases heterogeneity which in turn impacts stylolite nucleation moreover the geochemical data support that clay along the stylolite is not authigenic but a relict from impurities in the limestone host rock the statistical approach of stylolite spacing used in this study which is different than previous studies reinforces the model of random occurrence of stylolites in carbonate lithologic units this study shows that local stresses in tectonically passive areas may allow the formation of rare oblique stylolites with peaks perpendicular to the stylolite plane estimation of the amount of limestone dissolved during stylolitization minimum 7 to 12 of the depositional limestone and the volume of sparite in the host rock up to 1 6 of the compacted limestone suggests that the pressure solution fluids cemented the micropores reducing porosity to about 10 from a common porosity of about 40 in mechanically compacted chalk this study thus highlights the importance of microporosity as a sink for burial cements an observation difficult to make in thin section analysis of stylolite infills at site u1352 shows no evidence that the stylolites acted as conduits for diagenetic fluids unless if the fluid was host rock buffered and thus its chemistry indistinguishable from that of the host rock the link between siliciclastic content in carbonate rocks and the spacing and amplitude of stylolites improves understanding of burial compaction processes predicting the morphology and spacing of stylolites in the subsurface can be used to identify baffles to cross stylolite fluid flow or cementation of microporosity influencing heterogeneity of petrophysical properties in subsurface reservoir host rocks

heterogeneities and diagenetic control on the spatial distribution of carbonate rocks acoustic properties at the outcrop scale abstract carbonate rocks are characterized by a high heterogeneity of their properties at the outcrop scale that results from complex interactions between sedimentary diagenetic and fracturing processes here we show acoustic p wave velocity measurements conducted step by step on three decameter scale outcrop surfaces in cretaceous carbonate rocks with contrasted heterogeneities two shallow water highly fractured cassis and low fractured calissanne carbonates and one basin highly compacted grignantes p wave measurements were compared to outcrop geology and with plug porosity p wave velocity laboratory measurements and a thin section study results show a strong scale dependence of p wave velocities which always are lower at the decimeter scale than at the plug scale vp in situ versus vp plug large discrepancies 2000 m s highlight the signature of large heterogeneities open fractures stylolithes and lower discrepancies in situ distribution follows the dip of the ripple foresets which are controlling grain sorting and porosity in calissanne outcrop the near isotropic vp are explained by an early intense fracturing and cementation in cassis outcrop and the strong horizontal anisotropy with a hole effect behavior on variograms highlights the late re opening of multiple intervals of compaction bands in grignantes these results illustrate that the early diagenesis coupled to fracture or stylolithe reactivation opening are two key processes that explain the outcrop scale p wave velocity distribution anisotropy in carbonates

three dimensional structural model of composite dolomite bodies in folded area upper jurassic of the etoile massif southeastern france the three dimensional 3 d geometry of fractures and fault related dolomite is difficult to access with classical subsurface prospection tools therefore we have investigated an outcrop to improve the subsurface prediction for complex dolomite bodies this outcrop is located in the etoile massif southeastern france within a fault bend anticline the sedimentary units are of upper triassic to lower barremian age the fold results from the pyreneo provencal shortening during the late cretaceous to the eocene the anticline hosts three types of dolomite bodies 1a massive dolomite of middle to late oxfordian age 1b syndepositional stratabound dolomite of tithonian age and 2 isolated dolomite bodies associated with fractures and faults large scale geometries of fault related dolomite bodies have been modeled in 3 d the 3 d geometries of these bodies show diapir finger and wall like structures these bodies are located close to the main thrusts in strata of middle oxfordian to early barremian age and are linked to the compressive fold bending phase during the late cretaceous fault related dolomitization occurred because of magnesium removal from the hydraulic brecciation and the pressure solution of type 1 dolomite with overpressured fluids these fluids flushed upward along the main thrust and laterally by following the reservoir property contrasts in the host rocks fault related dolomite bodies are either spread far apart from faults in grainy limestones with good initial reservoir properties or are restricted to fault vicinity in muddy limestones with poor initial reservoir properties the study of the structural and stratigraphic framework was essential in the understanding of the dolomitization process

upper bound on stylolite roughness as indicator for amount of dissolution stylolites are rough surfaces that form by localized dissolution despite their abundance in carbonates and sandstones and their importance for fluid flow and rock deformation many fundamental issues concerning their structure and evolution are still unresolved this manuscript studies the roughening of long parallel stylolites here we report measurements of stylolite surface roughness at a scale larger than ever measured before 10 2 10 1 m measurements were performed using ground based lidar on 6 naturally exposed surfaces of 4 km long stylolites in northern israel producing a topographic map of the surfaces from which roughness characteristics were derived our results show that for length scales below 50 cm the stylolite morphology exhibits self affine behavior with a hurst exponent h 0 65 consistent with previous studies made on smaller samples the self affine behavior changes for measurements made on scales above 50 cm with h decreasing almost to zero on long length scales this observed upper bound of self affine roughness is measured here for the first time but has been previously predicted by theory ebner et al 2009b koehn et al 2007 our measurements support these theoretical models and together with them present a scenario in which the investigated stylolites evolve from preferential dissolution along an existing surface that was initially smooth and progressively roughened with time such a mechanism of stylolites growth is different from previously suggested mechanisms for other classes of stylolites which might propagate sideways from an initial defect based on the theoretical roughening model that we adopted the upper limit to fractality for this class of stylolites may be used as a measure of the amount of dissolution on stylolites indeed the amount of dissolution on the stylolites in our field site which we calculated from the upper limit to fractality is comparable to though slightly larger than our estimates of dissolution from two additional independent techniques reflecting compactive strain of 50

unsaturated zone tritium and chlorine 36 profiles from southern australia their use as tracers of soil water movement in this paper we present seven unsaturated zone profiles of 36cl and three 3h profiles from southern australia all profiles show single peaks corresponding to high radionuclide fallout from nuclear testing in the 1950s and 1960s the profiles are used to estimate rates of water movement leading to recharge of the groundwater among these profiles is the first profile on which high concentrations of 36cl have been found below a 2 m depth in this profile 3h and 36cl peaks coincide in six of the seven profiles total 36cl fallout was found to be between 1 2 and 2 4 1012 atoms m 2 and is of similar magnitude to that found at similar latitudes in the northern hemisphere comparisons of soil water fluxes estimated with 3h 36cl and chloride are briefly discussed

a field method to determine unsaturated hydraulic conductivity using flow nets a practical new field method is proposed to evaluate hydraulic conductivity in partially saturated media near a water impoundment the new method is an inverse procedure which utilizes a flow net constructed from the steady state total hydraulic head distribution around the water source in the vicinity of constant head sources and downstream along any stream tube wetness and conductivity generally decrease knowing the stream tube geometry and hydraulic gradient from the flow net darcy s law is used to determine unsaturated hydraulic conductivities within the stream tube relative to some segment of the stream tube where conductivity is known this approach was used successfully to predict the unsaturated hydraulic conductivity which was input to two variably saturated numerical models utilizing total hydraulic head fields generated by the models this procedure is also applied to pressure head and water content data collected in the field surrounding a constant head borehole infiltration test originally designed to determine only saturated hydraulic conductivity above the water table for practical purposes the new procedure compares very favorably with 1 results of a field experiment to obtain unsaturated hydraulic conductivity in situ using the instantaneous profile method and 2 values of unsaturated conductivity calculated from field and laboratory measurements of water content and pressure head

spatial and temporal variability of water percolation and movement in a system of longitudinal dunes western negev israel subsurface lateral flow has previously been identified in dune areas where the average annual rainfall exceeds 200 mm very little is known about subsurface flow in sandy deserts with less than 100 mm of rainfall per year the present study deals with the water regime in a system of longitudinal dunes in the negev desert sixteen boreholes were dug down to a depth of 6 m across a sandy ridge and the adjacent corridor soil moisture and water movement were monitored with a neutron probe during two consecutive years the first year had been relatively wet and in the following year the rainfall was slightly lower than the long term average the data obtained show that in an average year water percolation is limited to 60 cm with no lateral water movement deeper percolation in the range 180 400 cm occurs in response to rainy spells with about 100 mm of cumulative rain within two months the process involves subsurface lateral flow and water movement by the piston effect the lateral flow on the flanks of the dune is explained by differences in hydraulic conductivities within the sloping layers 1997 by john wiley sons ltd

are stylolites fluid flow efficient features abstract it sounds counter intuitive to consider contraction features such as stylolites as potential conduits for flow however this idea has grown since 1980 with geoscientists finding many examples principally in carbonate reservoirs where stylolites can be considered as fluid efficient features among others these features can be reactivated stylolites can generate positive porosity and permeability anomalies can drive corrosive fluids or can remain open in an overpressured system conversely stylolites can also be closed forever these impermeable stylolites can generate permeability anisotropy that may impact fluid movements stylolites require particular attention to evaluate whether they act as drains or as barriers to flow compartmentalisation we review some of the key studies of the past thirty years with a special attention to the most recent ones we end up considering their mechanical origin their nucleation and growth their past and present impact on reservoir properties and performances as key factors influencing the flow efficiency differentiation of these features this short review presents the latest theories and observations about stylolites with respect to the key factors aforementioned the authors support herein that a distinction should be made between processes occurring in the past and the present day impact the stylolite had on reservoir properties

sedimentary stylolite networks and connectivity in limestone large scale field observations and implications for structure evolution stylolites are rough surfaces formed by localized rock dissolution and prevalent in carbonates and other sedimentary rocks their impact on porosity and permeability and capacity to accommodate compactive strain are well documented this paper presents a meso scale field study on sedimentary stylolites in carbonates characterizing large scale distributions of stylolites including measurements conducted on longer than kilometer long stylolites our field study suggests that on large scales connections between stylolites become important since connectivity and also lack of connectivity are expected to play a significant role in strain accommodation and hydraulic rock properties we suggest that large scale analysis may require a new characterization scheme for stylolites populations based on their connectivity we therefore divide sedimentary stylolite populations into three end member types which are correlated with the three possibilities for percolation of such systems isolated stylolites with zero percolation connectivity long parallel stylolites with 2 dimensional percolation connectivity and interconnected stylolite networks with 3 dimensional percolation connectivity new statistical parameters and measures are devised and used to quantitatively characterize the different population types schematic mechanistic models are then offered to explain the evolution of the three end member connectivity classes in addition we discuss the effect on fluid flow of the different population types

on the effects of petrographic composition on coalbed methane sorption abstract the effect of petrographic composition on the methane sorption capacity has been determined for a suite of coals and organic rich shales subbituminous and bituminous coals were separated into bright and dull lithotypes by hand picking the methane sorption capacities range between 0 5 and 23 9 cm 3 g at a pressure of 6 mpa the low volatile bituminous canmore coal and the anthracite sample have the highest capacities with the natural coke having the lowest for low rank coals there is no significant difference between bright and dull samples except for one coal with the dull sample having a greater sorption capacity than its bright equivalent for higher rank coals the bright samples have a greater methane capacity than the dull samples and the difference between sample pairs increases with rank the boghead coal samples have the highest sorption capacities in the liptinite rich coals suite and are higher than subbituminous to medium volatile bituminous samples pore size distribution indicates that methane is held as solution gas in liptinite rich coals and by physical sorption in micropores in liptinite poor coals these contrasting processes illustrate that liptinite rich samples need to be independently assessed the positive relationship between reactive inertinite content and methane sorption capacity occurs within the subbituminous to medium volatile bituminous coals because the reactive inertinite is structurally similar to vitrinite and have a higher microporosity than non reactive inertinite reactivity of inertinite should be assessed in cbm studies of dull coals to provide a better understanding of petrographic composition effects on methane capacity

a 2000 year geochemical record of palaeoclimate and hydrology derived from dune sand moisture abstract chloride concentrations in the interstitial water of the unsaturated zone in dune sands of the badain jaran desert northwestern china have been used to examine the recharge history over the last 2000 years using a chloride mass balance approach the estimated 0 9 mm yr 1 recharge represents approximately 1 of annual precipitation in the western part of the desert and this low but finite infiltration allows preservation of this record the 30 m deep profile yields a total archive equivalent to 2050 years with well preserved climatic events of 30 50 years duration periods of relatively dry years occurred during ad 100 250 350 600 870 1220 1330 1450 1570 1720 1780s and 1900 1970 the unsaturated zone profile provides a robust climate record with a resolution of 20 yr comparable favourably to tree ring and ice core records in this region

climatic controls on diffuse groundwater recharge in semiarid environments of the southwestern united states 1 although there is no diffuse groundwater recharge at many semiarid sites evidence for diffuse recharge exists at some locations where mean annual precipitation is much less than mean annual potential evapotranspiration particularly where soils are coarse and rainfall variable is substantial we investigate the climatic controls on diffuse recharge using a one dimensional variably saturated flow model the model is driven by a stochastic parameterization of climate that includes storm size distribution and seasonality of precipitation p and potential evapotranspiration pet constrained by data from 536 weather stations in the southwestern united states storm size distribution and seasonality determine the frequency and duration of intervals when p exceeds pet which controls the flux of water past the root zone for coarse soils climates with large infrequent storms yield recharge when exceeds 0 4 compared with 0 7 for a typical climate recharge through fine soils is insensitive to storm size and occurs at 0 8 seasonality has a stronger influence on recharge than storm size distribution and the effects are similar for coarse and fine soils recharge is relatively insensitive to rainfall seasonality in contrast the typical pet annual cycle lowers of the recharge threshold by 0 3 the relative timing of p and pet maxima is critical recharge occurs at values that are lower by 0 2 when the rainy season occurs during winter instead of summer over the range of climate and soils examined values at the recharge threshold varied from 0 2 to 0 7 therefore and alone are insufficient to predict where recharge will occur

extensional veins induced by self similar dissolution at stylolites analytical modeling abstract stylolites are surfaces of localized dissolution observed in rocks many stylolites share a common morphological feature the amount of dissolved rock in the center of the seam is proportional to the stylolite s length field observations demonstrate that stylolites can locally influence formation of veins the developed analytical model of the indirect solution of eshelby s transformation problem calculates the stress field within and around the stylolite the results suggest that growth of a stylolite with an elliptic dissolution pattern generates a local non uniform stress field in the host rock which is in turn accommodated by brittle mode i fracturing in the stylolite midsection further resulting in veins formation parametric analysis and qualitative comparison with anticrack model describing stress field within and around stylolite are conducted

the permeability of stylolite bearing limestone abstract stylolites are planar features that form due to intergranular pressure solution due to their planar geometry and relative abundance in limestone reservoirs their impact on regional fluid flow has attracted considerable interest we present laboratory permeability data that show that stylolites can be considered as conduits for flow in the stylolite bearing limestones measured a combination of analysis techniques shows that this is due to a zone that surrounds these stylolites that is more porous and contains larger pores than the host rock our data also show that the water permeability of a sample containing a stylolite parallel to fluid flow is typically lower than its permeability to gas explained here as a result of the expansion of minor amounts of clay found in the stylolite and that due to their microstructural similarities tectonic and sedimentary stylolites affect sample permeability similarly finally we show that the permeability anisotropy that develops in the rock mass due to the presence of sedimentary stylolites makes it appear as though the stylolites are acting as barriers to fluid flow and may explain the discrepancy between laboratory measurements and field scale observations this approach can provide estimates for the equivalent permeability and permeability anisotropy for stylolite bearing limestone reservoirs worldwide

quantitative characterization of low rank coal reservoirs in the southern junggar basin nw china implications for pore structure evolution around the first coalification jump abstract the assessment of coalbed methane cbm reservoirs can provide insights into the evolution of the pore structure systems around the first coalification jump fcj the southern junggar basin a typical low rank coal bearing basin in northwestern china has been of interest to scientists and policy makers due to its abundance of cbm resources and favourable conditions for cbm enrichment a total of 28 coal samples from the middle jurassic xishanyao formation collected from 11 sampling sites in the central segment of the southern junggar basin were analyzed in this study these samples were quantitatively characterized and comprehensively evaluated using macroscopic to nanometer scale methods including macroscopic coal description proximate analysis vitrinite reflectance measurements maceral analysis low pressure nitrogen adsorption lpna scanning electron microscopy sem mercury intrusion porosimetry mip and nuclear magnetic resonance nmr the results show that the xishanyao low rank coals are characterized by low moisture contents low or low medium ash yields eastern and western parts high volatile matter contents moderate vitrinite contents and high inertinite contents the physical property of the xishanyao coals generally displays heterogeneity with the specific surface area the total pore volume the air permeability and the transverse relaxation time t2 ranging from 0 116 to 15 983 m2 g 0 461 10 3 to 13 37 10 3 cm3 g 0 001 to 151 66 md 0 987 10 6 to 0 149 m2 and 1 44 174 22 ms respectively a new parameter namely micropore volume proportion per unit nano meter is proposed micropore and transition pore volume per nm specific surface area total pore volume dn1 and dn2 lpna fractal dimension all first increase then decrease and finally increase with rising coal rank while the maximum and minimum values of the maximum vitrinite reflectance ro max occur at 0 58 0 59 and 0 65 0 66 the boundary of ro max corresponding to the fcj can be further defined from 0 5 0 6 to 0 58 0 59 based on the evolution of adsorption pore structures thus pore structure parameters related to adsorption capacity are controlled predominantly by coal rank in addition tectonic deformation has a strong impact on seepage pore structure but only a slight impact on that of adsorption pore which leads to an ambiguous correlation or a complex trend between mesopore macropore content dmip fractal dimension of mip and coal rank around the fcj this study reveals the complex variation of pore structure evolution of low rank coals and the significant influence of the fcj on physical properties of coalbed methane reservoirs

estimating recharge based on long term groundwater table fluctuation monitoring in a shallow aquifer of malaysian tropical rainforest catchment a practical and reliable approach was applied to investigate the groundwater dynamics and obtain natural direct recharge based on the time series of water table fluctuation in moderately flat coastal area with a shallow water table and tropical rainforest weather drainage rate was about 0 034 m day in the study area as estimated by falling groundwater table in period of no rainfall and specific yield values ranged between 0 11 and 0 23 by calculating depth dependent specific yield based on soil water storage for layering soils the method was applied to the monthly data of shallow aquifer at eight field sites in north kelantan river catchment in the period of 1991 2011 the cross correlation and partial cross correlation reveal the acceptable correlation between the water table fluctuation and the rainfall data assuming the time lag from precipitation to water table response is negligible due to shallow water table recharge rates vary with the field sites and mainly depend on soil type and rainfall rather than surface geology although computer simulation with mrcr code was implemented with limited data two series still results are just slightly greater than the field data which indicated the method successfully employed and can be applied in areas with similar conditions in future

spatial distribution of chloride and nitrate within an unsaturated dune sand of a cold arid desert implications for paleoenvironmental records abstract based on chloride mass balance approach we used two tracers cl and no 3 to study the interstitial water in four profiles of an unsaturated dune sand the aim was to reconstruct the recharge history and use this to infer the long term related climate changes and vegetation transitions in a cold arid desert region of northwestern china the estimated recharge rate of 0 21 to 0 59 mm year 1 represented approximately 0 2 to 0 7 of the annual precipitation in the western badain jaran desert the orientation of a megadune s slopes appeared to greatly affect recharge variability below the near surface peaks the total cumulative no 3 n inventories ranged from 61 to 121 kg ha 1 the near surface peaks in no 3 n with larger no 3 n cl molar ratios reflected active modern n fixation by cyanobacteria and the nitrate enrichment deeper in the unsaturated moisture zone indicated drier periods with less vegetation limited nitrate fixation or a combination of the two

factors affecting channel infiltration of floodwaters in nahal zin basin negev desert israel although floods in arid environments have been documented considerable uncertainties still exist as to the floodwater and in channel infiltration relationships in desert alluvial channels the prime cause of flood discharge attenuation is water loss by infiltration into the alluvium the present study documents flows in nahal zin israel their infiltration into the channel bed and the resultant change in the alluvium moisture content the study uses a systematic combination of two experimental scales the cross section scale and the reach scale direct measurements of moisture distribution in the active channel during floods were made using time domain reflectometry twelve flow events were recorded flow patterns and their respective alluvium moisture content were analysed a trench was dug in the alluvium for the study of alluvium properties and time domain reflectometry sensor installation the alluvium was characterized in terms of size distribution and sediment stratigraphy structure and composition two main alluvial structures closed and open affected the advance of the wetting front and water losses alluvial units with an open structure clast supported reached their maximum moisture content faster than closed structure units matrix supported small sized particles and matrix supported layers reduced infiltration rate the measured velocities of the wetting front were 0 33 and 2 88 m h 1 for small and large floods respectively the wetting front moved downward lateral movement was negligible copyright 2016 john wiley sons ltd

what controls diffuse fractures in platform carbonates insights from provence france and apulia italy abstract fractures are widespread in rocks and regional opening mode arrays are commonly ascribed to major tectonic events however fractures occur in otherwise undeformed rocks some of these are early developed features independent of tectonics and forming a background network at regional scale to overcome this lack of understanding two hydrocarbon reservoir analogues from platform carbonates have been targeted the provence se france and the apulian platform se italy in both areas an early fracturing stage has been observed made of high angle to bedding opening mode fractures and bed parallel stylolites these features developed synchronously during the first burial stages and prior to major tectonic events the fracture sets are not genetically related to the present day layering contrarily fractures developed in a brittle media where facies transitions were not sharp and did not act as mechanical discontinuities carbonate facies distribution and early diagenetic imprint constrained the mechanical stratigraphy when fractures occurred in addition we observed that fractures related to late tectonic inversion were partly inhibited indeed rock mechanical properties change through time characterizing the temporal evolution of carbonate rocks has revealed that diagenesis and sedimentary facies are the prime actors for brittleness and mechanical layering in carbonates

variety of stylolites morphologies and statistical characterization of the amount of heterogeneities in the rock the surface roughness of several stylolites in limestones was measured using high resolution laser profilometry the 1d signals obtained were statistically analyzed to determine the scaling behavior and calculate a roughness exponent also called hurst exponent statistical methods based on the characterization of a single hurst exponent imply strong assumptions on the mathematical characteristics of the signal the derivative of the signal or local increments should be stationary and has finite variance the analysis of the measured stylolites shows that these properties are not always verified simultaneously the stylolite profiles show persistence and jumps and several stylolites are not regular with alternating regular and irregular portions a new statistical method is proposed here based on a non stationary but gaussian model to estimate the roughness of the profiles and quantify the heterogeneity of stylolites this statistical method is based on two parameters the local roughness h which describes the local amplitude of the stylolite and the amount of irregularities on the signal m which can be linked to the heterogeneities initially present in the rock before the stylolite formed using this technique a classification of the stylolites in two families is proposed those for which the morphology is homogeneous everywhere and those with alternating regular and irregular portions 2006 elsevier ltd all rights reserved

stylolites porosity depositional texture and silicates in chalk facies sediments ontong java plateau gorm and tyra fields north sea comparison of chalk on the ontong java plateau and chalk in the central north sea indicates that whereas pressure dissolution is controlled by effective burial stress pore filling cementation is controlled by temperature effective burial stress is caused by the weight of all overlying water and sediments as counteracted by the pressure in the pore fluid so the regional overpressure in the central north sea is one reason why the two localities have different relationships between temperature and effective burial stress in the chalk of the ontong java plateau the onset of calcite silicate pressure dissolution around 490 m below sea floor bsf corresponds to an interval of waning porosity decline and even the occurrence of proper stylolites from 830 m bsf is accompanied by only minor porosity reduction because opal is present the pore water is relatively rich in si which through the formation of ca silica complexes causes an apparent super saturation of ca and retards cementation the onset of massive pore filling cementation at 1100 m bsf may be controlled by the temperature dependent transition from opal ct to quartz in the stylolite bearing chalk of two wells in the gorm and tyra fields the nannofossil matrix shows recrystallization but only minor pore filling cement whereas microfossils are cemented cementation in gorm and tyra is thus partial and has apparently not been retarded by opal controlled pore water a possible explanation is that due to the relatively high temperature silica has equilibrated to quartz before the onset of pressure dissolution and thus in this case dissolution and precipitation of calcite have no lag this temperature versus effective burial stress induced difference in diagenetic history is of particular relevance when exploring for hydrocarbons in normally pressured chalk while most experience has been accumulated in the over pressured chalk of the central north sea

hydrologic issues in arid unsaturated systems and implications for contaminant transport analysis of unsaturated flow and transport in arid regions is important not only in water resource evaluation but in contaminant transport as well partic ularly in siting waste disposal facilities and in remediat ing contaminated sites the water fluxes under consid eration have a magnitude close to the errors inherent in measuring or in calculating these water fluxes which makes it difficult to resolve basic issues such as direction and rate of water movement and controls on unsaturated flow the purpose of this paper is to review these issues on the basis of unsaturated zone studies in arid settings because individual techniques for estimating water fluxes in the unsaturated zone have limitations a variety of physical measurements and environmental tracers should be used to provide multiple independent lines of evidence to quantify flow and transport in arid regions the direction and rate of water flow are affected not only by hydraulic head gradients but also by temperature and air pressure gradients the similarity of water fluxes in a variety of settings in the southwestern united states indicates that vegetative cover may be one of the pri mary controls on the magnitude of water flow in the unsaturated zone however our understanding of the role of plants is limited most unsaturated flow in arid systems is focused beneath topographic depressions and diffuse flow is limited thick unsaturated sections and low water fluxes typical of many arid regions result in preservation of paleoclimatic variations in water flux and suggest that deep vadose zones may be out of equilib rium with current climate whereas water movement along preferred pathways is common in humid sites field studies that demonstrate preferential flow are restricted mostly to fractured rocks and root zones in arid regions results of field studies of preferential flow in humid sites generally restricted to the upper 1 2 m because of shallow water tables cannot be applied readily to thick vadose zones in arid regions

significance of analytical particle size in low pressure n2 and co2 adsorption of coal and shale abstract this study examines the influence of analytical particle size on the surface area and mesopore and micropore volume data obtained from low pressure n 2 and co 2 adsorption analyses in response to the crushing of coal and shale pennsylvanian high volatile bituminous coal r o 0 57 and devonian to lower mississippian low maturity r o 0 57 and high maturity r o 1 30 shales from the illinois basin were progressively crushed from chunks 7 mm to 4 mesh 2 and co 2 adsorption analyses were performed on all the grain size fractions our results demonstrate that the values of both surface area and specific mesopore and micropore change with progressive crushing for example bet surface area of coal shows a steady increase from 2 m 2 g in the 4 mesh fraction to 4 7 m 2 g in the 200 mesh fraction for comparable size ranges bet surface area changes from 0 15 to 7 82 m 2 g in the low maturity shale and from 0 02 to 6 26 m 2 g in the high maturity shale changes in mesoporosity and microporosity parameters indicate that the coarsest fractions 4 mesh and larger are not suitable for low pressure adsorption analysis the values are very low and not reproducible dominantly because of equilibration problems our results demonstrate that the 60 mesh fraction for coal and the 200 mesh fraction for shales seem to be optimal and the most practical sizes for performing low pressure n 2 and co 2 adsorption analysis these analytical particle sizes yield results closest to the real values unbiased by disequilibrium

paleohydrologic implications of some deep soilwater chloride profiles murray basin south australia abstract a chloride mass balance approach to estimating soilwater ages and paleorecharge rates was tested in an area where considerable paleoclimatic data were available for comparison application of the method to data from four cores of the unsaturated zone taken in the western murray basin showed that the soil water at the base of the chloride build up or bulge associated with the root zone of the native mallee vegetation was emplaced during the last glacial interval at least 20 000 years bp furthermore recharge rates at this time were very low these observations agree with independent paleoclimate evidence that suggest that this time was colder windier and drier results are consistent with the notion that the root zone chloride bulge so typical of the murray mallee region developed in response to aridity that peaked during the last full glacial interval in australia the chloride method is a useful tool in paleohydrology especially when used in concert with other evidence

stylolite controlled diagenesis of a mudstone carbonate reservoir a case study from the zechstein_2_carbonate central european basin nw germany this study was developed within the framework of dgmk german society for petroleum and coal science and technology project 718 funded by the companies exxonmobil production deutschland gmbh gdf suez e p deutschland gmbh rwe dea ag and wintershall holding gmbh the authors would like to acknowledge exxonmobil production deutschland gmbh that kindly provided core data elliot humphrey thanks the natural environment research council nerc centre for doctoral training cdt in oil gas for a phd grant egr acknowledges agaur agencia de gestio d ajuts universitaris i de recerca for a beatriu de pinos research project additional funding was provided by the generalitat de catalunya government 2017sgr 824 and the spanish government projects cgl2015 66335 c2 1 r cgl2015 69805 p and pgc2018 093903 b c22 we acknowledge theresa straub and simon gast for their assistance during core data collection we would like to thank miroslaw mirek slowakiewicz and an anonymous reviewer for their critical and constructive comments together with the editorial guidance of edoardo perri

relationship between geomorphic settings and unsaturated flow in an arid setting because geomorphology can readily be mapped our ability to characterize unsaturated flow over large areas would be greatly enhanced if relationships between geomorphic settings and unsaturated flow could be identified the purpose of this study was to evaluate relationships between geomorphic settings and spatial and temporal variability in unsaturated flow at a field site in the chihuahuan desert of texas this study differs from most previous studies in the variety of geomorphic settings studied including drainage areas blanca draw and grayton lake playa and interdrainage areas basin fill deposits eolian sheets alluvial fans and a fissure density of data 50 sampled boreholes 3 31 m deep and variety of techniques physical chemical and electromagnetic used to quantify unsaturated flow spatial variability in unsaturated flow parameters is related to geomorphic settings the various geomorphic settings form distinct groups on a plot of chloride versus water potential interdrainage areas have low water potentials and high chloride concentrations indicating low water fluxes mean water fluxes estimated from chloride data ranged from 0 02 to 0 05 mm yr 1 in contrast localized topographic depressions fissure gully and borrow pit have high water potentials and low chloride concentrations which indicate high mean water flux 100 mm yr 1 these topographic depressions occupy 1 of the basin area drainage areas have low water potentials which indicate low water fluxes and low to moderate chloride concentrations which indicate higher water fluxes in the past 40 mm yr 1 short term variability in response to precipitation events was only monitored in topographic depressions the age of the pore water in the interdrainage areas spanned paleoclimatic variations 136 000 years at 25 m depth however most interdrainage profiles show negligible response to past climate fluctuations some profiles in eolian sheets showed increased water flux in response to pleistocene climate change the findings from this study indicate that geomorphology can provide valuable information on unsaturated flow and underscore the importance of localized topographic depressions for focusing unsaturated flow

coalbed methane resources and reservoir characteristics from the alberta plains canada abstract alberta has vast coal resources that may be a potential source of coalbed methane cbm exploration and research are currently underway in the province to quantify gas potential identify key geological factors that maximize cbm potential and identify the most favourable areas for cbm production potential there are four main coal zones within the plains and foothills of alberta the ardley coal zone of the plains is undergoing cbm exploration and production piloting much of this effort is within the west central pembina area horseshoe canyon formation coals of south central alberta were initially thought to have gas concentrations too low to be economic cbm producers it is these coals however that host alberta s first commercial cbm production project although similar in both geographic distribution and coal quality to horseshoe canyon coals not much is known regarding the gas potential of underlying coals of the belly river group the deeper mannville coals have some of the highest gas concentrations of alberta coals however they are also relatively deep and have lower permeability than the overlying belly river horseshoe canyon and ardley coals maximum gas in place for the plains and foothills has been estimated to be greater than 500 trillion cubic feet 1 42 10 13 m 3 although this number is very large little is known as to how much of this huge resource is actually producible a key challenge to producibility in alberta has been the generally low permeability of coals with the highest gas concentrations mannville coals and the moderate to low gas concentrations of higher permeability coals horseshoe canyon and ardley coals regionally coal distribution and average gas in place concentrations are calculated for the alberta plains identifying and explaining local areas with favourable cbm production characteristics within the regional setting is necessary to establish economic cbm plays within alberta there are currently several pilots and numerous exploration efforts underway in the province to demonstrate production potential this study integrates existing data with new data collected from key areas that show favourable cbm potential there is great opportunity for cbm development in alberta local areas have enhanced characteristics favourable to production ongoing geological investigations are needed to identify characteristics that will serve as an exploration tool for future cbm discoveries