the last phase of conodont evolution during the late triassic integrating biostratigraphic and phylogenetic approaches abstract for the upper triassic conodonts are the primary tools utilized in biostratigraphic investigations for an effective biostratigraphic zonation the species should be constrained by clear phylogenetic relationships in which the stratigraphic ranges and taxonomy are reliable unfortunately a phylogenetic framework for the late triassic pectiniform conodonts is almost missing except for particular intervals such as the carnian norian boundary the purpose of this study is to examine the latest norian and rhaetian pectiniform conodonts in detail in an attempt to determine their phylogenetic relationships by applying novel phylogenetic methodologies that incorporate both morphological and stratigraphic data this work is based on the conodont assemblages from the upper triassic strata of the lagonegro basin southern apennines southern italy and the cs var area north central hungary complemented with data from the literature the calibrated phylogenetic analysis of the latest norian and rhaetian conodonts supports a two step evolutionary history a first radiation 211 210 ma of the parvigondolella species and the first representative of the genus misikella followed by a second phase 206 5 205 ma leading to the final radiation of the misikella species furthermore the systematic revision of uppermost triassic conodonts is provided along with the description of misikella kolarae n sp

application of meteosat thermal data to map soil infiltrability in the central part of the lake chad basin africa in the central part of the lake chad basin africa the superficial quaternary aquifer 500 000 km2 forms the main water resource little is known about the aquifer recharge processes large piezometric depressions affect the aquifer and are still unexplained meteosat thermal composite data were used to infer qualitative information about time space variations of soil moisture over the aquifer meteosat data reveal that after heavy rainfall the piezometric depressions kadzell chari baguirmi appear cooler than the surrounding areas manga and harr the interpretation is that above the depressions rainwater accumulates at the surface and does not infiltrate deep into the ground leading to the observed cooler ground accordingly the depressions are characterized by low rainwater infiltrability which presumably results in a small rainfall recharge as far as we know this is the first time that an observed surface phenomenon is directly related to the origin of some piezometric depressions

arid zone groundwater recharge and salinisation processes an example from the lake eyre basin australia in arid central australia the 1 14 m km2 endorheic lake eyre basin leb experiences sporadic floods and contains saline shallow groundwater in this basin where on ground physical and chemical data are very sparse new observations of major ion chemistry stable isotopes 2h 18o 13c radiogenic isotopes 3h 14c and remote sensing modis data were used to investigate groundwater recharge and salinisation processes in 2006 2007 in january 2007 there was a large and intense local rainfall event followed by flooding to the normally dry lake eyre resulting from heavy rainfall in the northern leb that took 2 months to arrive at lake eyre groundwater chemistry from this study show no evidence of recharge from the floodwaters or the local rainfall however this does not preclude the process low transit times and low infiltrating volumes may mean that the recharge event has not yet been detected over the longer term the stable isotope chemistry indicates that groundwater is predominantly diffusely recharged during heavy local rainfall events 100 150 mm month and radiogenic isotopes reflect an older shallow groundwater efficiently mixing with recent decadal recharge the high total dissolved solids tds of regional shallow groundwater up to 52 5 g l is intrinsically linked with these recharge processes where infiltrating diffuse rainfall is evaporated and heavy rainfall events transport saline pore water saline due to evaporation in the unsaturated zone to the groundwater system the high tds of shallow groundwater beneath the dry lake eyre bed up to 322 g l is also controlled by evaporation however although evaporite minerals are prolific in the lake area the non conservative behaviour of br in pore water limits analysis of the role of halite mineral dissolution and precipitation reactions controlling groundwater salinity evaporation driven salinisation of shallow groundwater in arid central australia is distinct from the transpiration driven salinisation of groundwater in the australian murray basin located in a semi arid climate and results in relatively high groundwater salinity values compared with many other large arid zone endorheic basins across the world

salinity trends in the wheatbelt of western australia results of water and salt balance studies from cuballing catchment abstract a study of water and salt balances within a first order catchment in the western australian wheatbelt has shown that the salt load in the main surface drainage comes largely from groundwater discharging upstream from the basement highs and dykes that extend across the surface drainage and conductive channels within the regolith although salt fall from rainfall is about 2 0 g m 2 year 1 cl the stream load ranges from 180 to 850 g m 2 year 1 with an out input ratio of 100 425 salt storage in the catchment varies from 900 4000 g m 2 in the top 3 m to 27 000 71 000 g m 2 in the 3 15 m depth range and 5000 21 000 g m 2 below 15 m groundwater discharge calculated using br and cl as tracers for the groundwater component fluctuates between 20 and 40 of streamflow stream salinity during the last 3 years was below the long term average this is attributed to a reduction in groundwater discharge caused by low rainfall during this period the downward displacement and leaching of salt stored in the regolith indicates that if groundwater levels continue to rise the quantity and salinity of groundwater discharge will continue to increase causing further rises in stream salinity

late quaternary climates of the australian arid zone a review abstract aridity in australia has generally been associated with glacial intervals of the last few glacial cycles the causes and nature of aridity varied from north to south over the continent in northern and central australia reduced monsoon rain in global cold stages caused lakes and rivers to dry vegetation to become more sparse sand dunes to become active and dust advection to increase while the monsoon is correlated with warmer global temperatures and high sea levels overall the exact timing of the greatest development of the monsoon in stage 5 remains uncertain in southeastern australia the proxy records give a less clear picture while vegetation seems to have been more sparse in cold stages and sand dune activity and dust flux consequently greater records of runoff in rivers and lakes have mixed or opposite behaviour to northern or central australia the nature of aridity in southeastern australia is not analogous to conditions anywhere on the continent today greatly reduced temperatures over the central and southern interior greater influence of snow and periglaciation on runoff high groundwater tables lower rainfall and reduced atmospheric carbon dioxide levels may all have contributed to and interacted to produce the reconstructed picture of a cold sparsely vegetated arid landscape with large rivers and perennial lakes the largest changes in circulation patterns over the glacial cycle probably occurred in the location and or intensity of summer tropical convergence in northern australia over southern australia changes to the temperature and humidity of the westerly circulation have been more significant than the small fluctuations in latitude of the sub tropical high pressure ridge

la nina de australia contemporary and palaeo hydrology of lake eyre abstract the available records of inflows to lake eyre cover only forty five years their quality is questionable as longer time series of precipitation records are available the observed series of inflows to lake eyre can be extended with the help of a rainfall runoff model further reconstruction of the inflow series can be achieved by examining local evidence or with the help of proxy data however the limitations of these extensions and reconstructions of inflows are severe the inflows to lake eyre could be considered one of the most convincing manifestations of hydrological uncertainty however it is apparent that major flooding episodes in the lake eyre basin are most often associated with la nina phases of the el nino southern oscillation enso phenomenon the paper presents a hydrological description of the lake eyre basin and large scale contemporary and palaeo climatic patterns which affect the water balance of the catchment a simple water balance model has been constructed to determine storages of the lake when annual evaporation reaches equilibrium with annual runoff

geophysical surveys for identifying saline groundwater in the semi arid region of the central altiplano bolivia in the central part of the bolivian altiplano the shallow groundwater presents electrical conductivities ranging from 0 1 to 20 ms cm in order to study the origin of this salinity pattern a good knowledge is required of the geometry of the aquifer at depth in this study geophysics has been used to complement the sparse data available from drill holes one hundred time domain electromagnetic tdem soundings were carried out over an area of 1750 km2 about 20 geological logs were available close to some of the tdem soundings three intermediate results were obtained from the combined data i the relationship between the electrical conductivity of the groundwater and the formation resistivity ii geoelectrical cross sections and iii geoelectrical maps at various depths the limited data set shows a relationship between resistivity and the nature of the rock from the cross sections a conductive substratum with a resistivity of less than 1 m was identified at most of the sites at depths ranging from 50 to 350 m this substratum could be a clay rich formation containing brines using derived relationships maps of the nature of the formation sandy intermediate and clayey sediments were established at depths of 10 and 50 m discrimination between sand and clays was impossible where groundwater conductivity is high 3 ms cm in the central part of the area where the groundwater conductivity is low sandy sediments are likely to be present from the surface to a depth of more than 200 m clayey sediments are more likely to be present in the south east and probably constitute a hydraulic barrier to groundwater flow in conclusion the study demonstrates the efficiency of the tdem sounding method to map conductive zones copyright 2001 john wiley sons ltd

gis based groundwater spring potential mapping in the sultan mountains konya turkey using frequency ratio weights of evidence and logistic regression methods and their comparison summary in this study groundwater spring potential maps produced by three different methods frequency ratio weights of evidence and logistic regression were evaluated using validation data sets and compared to each other groundwater spring occurrence potential maps in the sultan mountains konya turkey were constructed using the relationship between groundwater spring locations and their causative factors groundwater spring locations were identified in the study area from a topographic map different thematic maps of the study area such as geology topography geomorphology hydrology and land use cover have been used to identify groundwater potential zones seventeen spring related parameter layers of the entire study area were used to generate groundwater spring potential maps these are geology lithology fault density distance to fault relative permeability of lithologies elevation slope aspect slope steepness curvature plan curvature profile curvature topographic wetness index stream power index sediment transport capacity index drainage density distance to drainage land use cover and precipitation the predictive capability of each model was determined by the area under the relative operating characteristic curve the areas under the curve for frequency ratio weights of evidence and logistic regression methods were calculated as 0 903 0 880 and 0 840 respectively these results indicate that frequency ratio and weights of evidence models are relatively good estimators whereas logistic regression is a relatively poor estimator of groundwater spring potential mapping in the study area the frequency ratio model is simple the process of input calculation and output can be readily understood the produced groundwater spring potential maps can serve planners and engineers in groundwater development plans and land use planning

solutions in chronostratigraphy the paleocene eocene boundary debate and aubry vs hedberg on chronostratigraphic principles abstract in several recent papers m p aubry et al have argued that hedbergian principles of chronostratigraphy are being violated by the international commission on stratigraphy ics when selecting global stratotype sections and points gssps for the formal divisions of the geological time scale the current debate over the definition of the paleocene eocene p e boundary has been a major focus of their arguments unfortunately aubry et al have obscured matters by misusing the term unit stratotype and by equivocally using the term stage for the very different concepts of synthem and global chronostratigraphic stage the p e boundary option most repugnant to aubry et al carbon isotope excursion cie p e thanetian ypresian boundary is perfectly compatible with h d hedberg s views in contrast another option preferred by aubry et al recognition of new 1 m y duration age stage between thanetian and ypresian is inconsistent with hedberg s views additional problems with the p e boundary arguments of aubry et al include the fact that a ypresian unit stratotype does not exist the fact that the base of the ypresian synthem is not immutable and the fact that the nannofossil tribrachiatus digitalis is of dubious relevance to the boundary debate as for chronostratigraphy in general aubry et al have misrepresented hedberg s views by 1 falsely claiming that the content of a stage is what determines its boundaries 2 misunderstanding the general concept of the boundary stratotype 3 distorting the base defines boundary principle 4 falsely claiming that traditional pre gssp chronostratigraphic boundaries cannot be changed 5 falsely implying that traditional stage unit stratotype boundaries can be adjusted by no more than 300 000 years when defining formal age stage boundaries with gssps 6 falsely claiming that the definition of a geochronologic chronostratigraphic boundary should precede its correlation 7 claiming that traditional unconformable stage boundaries may be suitable horizons for gssps 8 distorting the meaning of arbitrariness in regard to the definition of geochronologic chronostratigraphic boundaries and 9 claiming that gssps are inherently unstable in that they are subject to redefinition whenever a more powerful element of correlation is discovered if taken seriously the unit stratotype sanctifying chronostratigraphic philosophy of aubry et al would require the creation of perhaps dozens of new phanerozoic ages stages of relatively very short duration wherever there was a significant gap between two successive historical stage unit stratotypes for all of these reasons the arguments of aubry et al have no merit

comparative study of methods of preparing hydraulic head surfaces and the introduction of automated hydrogeological gis techniques abstract construction of hydraulic head surface hhs maps is the most commonly used technique for groundwater evaluation a review of methods used for constructing hhs maps showed that of the manual methods the hydrogeological interpretative technique produces a better surface than the equally spaced approach geostatistical methods gave similar surfaces to the manual methods they share the problem of groundwater contours intersecting surface contours and the inability to identify groundwater discharge areas the results showed that the automated hydrogeological gis geographical information system techniques which take into account the hydrogeomorphic and topographic controls produced the most realistic surfaces groundwater contours follow the hydrogeomorphic trends do not intersect surface contours and can properly identify areas of groundwater discharge the major advantage of the hydrogeological gis technique is the ability to prepare hhs maps with a small number of data points it is also possible to use regressions from other catchments to prepare hhs maps for catchments with similar hydrogeomorphic characteristics and elevation ranges but which have no data

mechanisms affecting streamflow and stream water quality an approach via stable isotope hydrogeochemical and time series analysis stable isotope deuterium and hydrogeochemical chloride nitrate data in rainfall streamflow and deep and shallow groundwaters have been applied to develop an understanding of the mechanisms of streamflow generation and nutrient discharge from a 27 km2 rural catchment near perth western australia intensive sampling of the stable isotopic composition of rainfall groundwater and streamflow during the winter flow periods of 1987 and 1988 identified several significant rainfall events that were up to 90 depleted in deuterium relative to deep and shallow groundwaters in the catchment isotopic responses in streamflow to the depleted rainfall could be discerned on three time scales 1 the rainfall events themselves i e 1 to 2 days 2 isotopic relaxation periods lasting up to 6 weeks as streamflow values slowly returned to their preevent values and 3 a longer seasonal scale response of 2 to 3 months caused by a seasonal isotopic trend in rainfall composition and an increase in the proportion of groundwater in streamflow toward the end of the flow period the sharp isotopic responses in streamflow observed in this study were in marked contrast to the attenuated responses observed in a previous study on a 1 km2 catchment under native forest in the same region this contrast reflects the different roles of the shallow groundwater system in streamflow generation between the two catchments under different land use kalman filtering techniques were applied to investigate the numerical functions linking rainfall amount and streamflow volume and their respective stable isotopic compositions the purpose of the numerical analysis was to estimate the average lag between rainfall and streamflow thereby quantifying the time scales of streamflow generation analysis of streamflow water quality has been shown that the bulk of nutrients and solutes are discharged from the catchment at the onset of flow in response to the first major rainfall events of the winter period integration of the isotopic hydrogeochemical and numerical analysis presents a consistent view that surface and subsurface storm flow are important streamflow generating mechanisms over the time scale of a rainfall event postevent periods of isotopic relaxation in streamflow are due to discharge of groundwater to streamflow from an ephemeral perched aquifer there is evidence for an increasing component of deep groundwater in streamflow as streamflow declines toward the end of the flow period in october and november

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

global boundary stratotype section and point gssp for the anthropocene series where and how to look for potential candidates abstract the anthropocene as a potential new unit of the international chronostratigraphic chart which serves as the basis of the geological time scale is assessed in terms of the stratigraphic markers and approximate boundary levels available to define the base of the unit the task of assessing and selecting potential global boundary stratotype section and point gssp candidate sections a required part of the process in seeking formalisation of the term is now being actively pursued here we review the suitability of different stratified palaeoenvironmental settings and facies as potential hosts for a candidate gssp and auxiliary sections and the relevant stratigraphical markers for correlation published examples are evaluated for their strengths and weaknesses in this respect a marked upturn in abundance of radioisotopes of 239pu or 14c approximately in 1952 and 1954 ce respectively broadly coincident with a downturn in 13c values is applicable across most environments principal palaeoenvironments examined include settings associated with accumulations of anthropogenic material marine anoxic basins coral reefs estuaries and deltas lakes at various latitudes peat bogs snow ice layers speleothems and trees together many of these geographically diverse palaeoenvironments offer annual subannual laminae that can be counted and independently dated radiometrically e g by 210pb examples of possible sections offer the possibility of correlation with annual seasonal resolution from among such examples a small number of potentially representative sites require the acquisition of more systematic and comprehensive datasets with correlation established between sections to allow selection of a candidate gssp and auxiliary stratotypes the assessments in this paper will help find the optimal locations for these sections

evaporation rate from a salt pan estimates from chemical profiles in near surface groundwaters evaporation of water from saturated saline soils or sediments induces gradients of the solutes in the remaining interstitial solution these gradients lead to a systematic and predictable solute distribution in the soil solution which may be used in some cases to estimate the rate of evaporation simple one dimensional transport models for the distribution of cl and br indicate net evaporation rates from the salt covered surface of lake eyre south australia of between 0 9 and 2 8 cm yr 1 the former is a minimum estimate averaged over 20 yrs which includes the major 1974 filling event while the latter reflects the most recent summer evaporation period

non conservative behavior of bromide in surface waters and brines of central andes a release into the atmosphere abstract the transfer of reactive bromine into the atmosphere was recently observed by honninger et al honninger g bobrowski n palenque e r torrez r platt u 2004 reactive bromine and sulfur emission at salar de uyuni bolivia geophys res lett 31 doi 10 1029 2003gl018818 in a large salt pan of the bolivian altiplano the salar de uyuni however bromide is considered to be an excellent conservative tracer which leads to the questioning of its actual conservation in surficial geochemical processes the relation between bromide and lithium thought to be a conservative component in waters and brines of the central andes points to a depletion of br relative to li in uyuni brines of about 50 300 kg day a flux close to that measured by honninger et al 2004 200 kg day such values are very low in regard to the size of the salar 5 30 g km 2 day salt efflorescences have a much higher surface area than a flat salt crust which should enhance the release of bromine leach solutions of salt efflorescences in closed basins of northern chile are compared to their parent waters conservative components should have the same concentration ratios in both solutions actually a strong depletion in br is observed in the leach solutions which could suggest a significant release of br from the salt into the atmosphere during the rainy season efflorescences are leached and their dissolved components brought in saline lakes and salars evaporative profiles show a slight but noticeable fractionation between li and br which could be due to the contribution of br depleted leach solutions of salt efflorescences therefore bromide does not behave conservatively in surface waters and brines of the central andes if the loss of br is really due to its transfer into the atmosphere then the flux would be much higher than that estimated for the salar de uyuni alone numerous salt pans saline lakes and widespread efflorescences covering large land surfaces would contribute significantly more reactive bromine into the atmosphere

dynamics of floodplain island groundwater flow in the okavango delta botswana abstract surface water groundwater interactions play a crucial role in the hydrology and ecology of the okavango delta the hydrology of the delta is dominated by the annual arrival of a flood wave which is distributed over an number of branches subsequently the flood water feeds the phreatic aquifers underlying the delta islands in order to evaluate the seasonal and long term dynamics of the surface water groundwater interactions between the floodplains and the islands a network of piezometers located in various locations of the delta was monitored groundwater table fluctuations observed for up to 6 years were analysed and modelled using groundwater flow models the floodplain island groundwater flow is in general very dynamic and driven by island evaporation and transpiration a typical small to medium sized island width 500 m and at the perimeter of the flooded area is the influence of long term antecedent conditions apparent the knowledge gained during this study will be used for the improvement of the hydrological and hydro ecological model of the delta and can be useful for the description of floodplain dynamics in semi arid regions in general

structural complexity at and around the triassic jurassic gssp at kuhjoch northern calcareous alps austria one of the key requirements for a global stratotype section and point gssp is the absence of tectonic disturbance the gssp for the triassic jurassic system boundary was recently defined at kuhjoch northern calcareous alps austria new field observations in the area of the triassic jurassic boundary gssp site demonstrate that the overturned tight and almost upright karwendel syncline was formed at semibrittle deformation conditions confirmed by axial planar foliation tight to isoclinal folds at various scales were related to a tectonic transport to the north brittle faulting occurred before and after folding as confirmed by tilt tests the rotation of structural data by the average bedding foliation is ubiquitous in the incompetent units including the kendlbach formation at the gssp a reverse fault inferred to be formed as a normal fault before folding crosscuts the gssp sections results in the partial tectonic omission of the schattwald beds and thus makes it impossible to measure a complete and continuous stratigraphic section across the whole kendlbach formation based on these observations the kuhjoch sections do not fulfil the specific requirement for a gssp regarding the absence of tectonic disturbances near boundary level

renewal rate estimation of groundwater based on radioactive tracers 3h 14c in an unconfined aquifer in a semi arid area iullemeden basin niger abstract estimation of groundwater recharge in arid and semi arid areas is difficult due to the low amount and variability of recharge a combination of radiotracers investigation based on simple mixing models allows direct investigation of relatively long term renewal rates of an aquifer the recharge process of the shallow continental terminal aquifer in the iullemeden basin niger was investigated using a geochemical and isotopic approach this study investigates the area in the one degree square of nianey 13 14 n 2 3 e in this area recharge is highly heterogeneous and mainly occurs through a drainage system of temporary streams and pools during the rainy season heterogeneity of the recharge is reflected through the wide variation in electrical conductivity and oxygen 18 content of the groundwater the carbon 14 activity range for most of the groundwater falls between 69 and 126 pmc showing pre and post aerial thermonuclear test recharge two renewal rate models have been investigated the first one models a well mixed reservoir and the second one is derived from a piston flow model in which mixing is in equal proportions major ions in tritium data analyses allow exclusion of non representative samples and confirm the carbon 14 renewal rate estimations both models give similar results for the relatively low renewal rate investigated in the area using carbon 14 the mean annual rates of groundwater renewal range from 3 to 0 03 of the aquifer volume with a median of 0 1 assuming the median is representative of the overall renewal rate of the area the recharge rate is in the order of 5 mm a 1 the shallow aquifer recharge extends from the last small humid period around 4000 a up to now high recharge rates are found in depressions whereas low recharge occurs below the plateaux

predictive modelling of management options for the control of dryland salinity in a first order catchment in the wheatbelt of western australia abstract a prototype flow model has been developed for cuballing catchment using modflow the results of the simulations showed that in a first order catchment the management strategies most likely to arrest salinity were reforestation and pumping the study confirmed that complete reforestation would arrest groundwater discharge and lead to the restoration of salinized land within the catchment it also showed that replanting the top 25 of the catchment was sufficient to reverse the salinity trend by reducing groundwater discharge to an acceptable level drainage along the main stream line was also effective in reducing groundwater levels in the unconfined aquifer and constrained the discharge in the area adjacent to the stream the simulations also showed that pumping reduced groundwater pressures in both the unconfined and confined aquifers a single windmill discharging at a rate ranging from 15 to 25 m 3 day 1 was sufficient to reduce water levels in the unconfined aquifer by more than 5 m and in the confined aquifer by more than 10 m however the pumping well must be correctly located in the catchment the preferred location is in highly transmissive areas with adequate aquifer thickness and upstream from geological structures restricting groundwater flow in western australia these areas are usually along drainage lines and within discharge areas

geochemistry of ground waters from the great artesian basin australia herczeg a l torgersen t chivas a r and habermehl m a 1991 geochemistry of ground waters from the great artesian basin australia j hydrol 126 225 245 ground waters from the confined lower cretaceous jurassic aquifer of the great artesian basin australia gab are characterised by na hco 3 type waters throughout the eastern and central parts of the basin and na sq c1 type waters in the western part sodium and bicarbonate increase in concentration from the northeastern margins to the southwestern discharge areas along the regional groundwater flowlines a mass balance and equilibrium model for major dissolved species and stable carbon isotopes of dissolved inorganic carbon show that the chemical trends observed are caused by mass transfer reactions involving cation exchange of na for ca mg carbonate dissolution and reactions between na and kaolinite to form na smectite the stable carbon isotopic composition of dissolved inorganic carbon dic increases from values of about 15 o near the basin margins to 6 o in the interior of the basin an inverse relationship exists between 6 3c and dic indicating addition of enriched carbon as the ground waters move basinwards a t2c 3c mass balance indicates that the trend toward heavier 6 3c values in the interior of the basin results from bacterial reduction of carbon dioxide to produce methane rather than dissolution of and equilibration with carbonate minerals the gab aquifer system is apparently open to co which is the product of in situ anaerobic fermentation producing co 2 enriched in t3c the chemical evolution of the major dissolved species and carbon isotope distribution in the eastern and central parts of the gab can then be envisaged as an initial pco 2 up to several orders of magnitude above atmospheric level is acquired within the recharge area by plant respiration and oxidation of organic matter in the soil zone initially silicate and carbonate minerals may dissolve at least in some parts of the basin resulting in increased alkalinity higher ca and mg concentrations and a 6 3c concentration of the dic of around 12 0 processes such as cation exchange of na for ca and mg in addition to the removal of some na by reverse weathering which produces a na smectite dominate in the interior of the gab the chemistry of ground waters derived from the western recharge areas is controlled by evaporite dissolution as indicated by very high ci br ratios

bathymetry topography effects on saltwater fresh groundwater interactions around the shrinking aral sea 1 large scale irrigational schemes have drastically reduced the surface water discharge into the aral sea causing a sea surface level lowering of more than 20 m since 1960 and severe water quality deterioration in the region we investigate the dynamics of submarine groundwater discharge sgd into the aral sea as well as the saltwater intrusion swi into the coastal groundwater around the aral sea during its shrinkage by using the u s geological survey sutra code results show that the regional topography and bathymetry largely influence sgd and swi transients as the aral sea shrinks considering the flat conditions that prevail in the southeastern aral sea and the irrigated amu darya delta sgd drops as the sea starts to shrink because the shoreline displacement prevents seawater inflow to the aquifer and subsequent return flow to the sea in this flat bathymetry case the groundwater discharging into the aral sea becomes as saline as the seawater because saltwater remains below the dried seabed in contrast for the steep bathymetry of the essentially uninhabited northwestern region the sgd increases as a combined effect of sea surface lowering density differences and storage with the sgd salinity remaining below seawater salinity and reflecting a considerable freshwater component considering the potential for groundwater pumping in the original coastline vicinity for freshwater supply use our results indicate a decreased risk of swi in the northwestern aral sea region under the post 1960 sea level lowering conditions

a review of calcareous nannofossil astrobiochronology encompassing the past 25 million years this paper presents a review of astrobiochronological calibration of recent to late oligocene calcareous nannofossil datum events biohorizons included in the paper are those of the widely used standard nannofossil zonations of martini e 1971 standard tertiary and quaternary calcareous nannoplankton zonation in farinacci a ed proceedings of the second international conference on planktonic microfossils roma rome ed tecnosci vol 2 pp 739 785 and okada h and bukry d 1980 supplementary modification and introduction of code numbers to the low latitude coccolith biostratigraphy zonation bukry 1973 1975 marine micropaleontology 51 321 325 as well as supplementary biohorizons proposed in the literature the biohorizons have been selected on the basis of the unambiguous taxonomy of the index taxa and their biostratigraphic usefulness we emphasise the application of rigorous methodology in nannofossil studies which permits an evaluation of biohorizons in terms of reliability and calibrates their potential correlatability astrochronological age estimates rely on the geologic timescale developed by the ics in 2004 with some new calibrations included we provide an overview of the relative position of biohorizons versus the astronomically calibrated ages of magnetic reversals and reference isotope stratigraphies surprisingly there are still few high resolution quantitative biostratigraphic studies of astrochronologically tuned sections in spite of the central role of such studies in addressing fundamental problems such as the tempo and mode of plankton evolution

periodic components in the diversity of calcareous plankton and geological events over the past 230 myr abstract we performed statistical analysis on high resolution records of the diversity of calcareous plankton planktonic foraminifera and calcareous nannoplankton and on records of global sea level marine isotopes 18 o 13 c 87 sr 86 sr large igneous province lip eruptions and dated impact craters over the last 230 myr results of continuous wavelet analysis cwt fast fourier transform fft spectral analysis and cross spectral analysis indicate that the records of diversity of calcareous nannoplankton cn and planktonic foraminifera pf and all of the geologic time series tested show similar dominant 25 33 myr cycles based on the statistical results best fit stationary periodic models for pf and cn evolutionary records can be constructed with t time in myr cn diversity 9 5 sin 2 t 7 5 myr 29 myr 4 8 sin 2 t 4 myr 15 3 myr and pf diversity 7 6 sin 2 t 12 myr 26 myr 3 sin 2 t 9 2 myr these periodic models describe major patterns in the diversity history such as 1 a sawtooth shaped 29 myr cycle for calcareous nannoplankton diversity with gradual increases and abrupt decreases in diversity 2 plateau shaped 26 myr cycles in the planktonic foraminiferal record with abrupt diversity increases and decreases and 3 the presence of 15 3 and 9 2 myr periodic components that modify the shapes of the 26 to 29 myr cycles except for the synchronous decreases in diversity of pf and cn at 65 and 34 ma the diversity extrema for the two planktonic groups have been on average 2 to 3 myr out of phase in the 30 myr cycle band cn diversity increased with sea level rise and increased paleotemperatures whereas pf diversity was in general greater during times of lower sea levels diversity of pf and cn was reduced at times of major lip eruptions and large impacts that follow 15 or 30 myr periodicities these results suggest that the diversity of calcareous plankton since their appearance in the early mesozoic has been modulated by long term cyclical changes in global environmental conditions and by periodic large volcanic and impact events the pacemaker or pacemakers for these cycles may be astrophysical geophysical or some combination of the two

isotope study of moisture sources recharge areas and groundwater flow paths within the eastern batinah coastal plain sultanate of oman oxygen and hydrogen isotope analyses of rainfall samples collected on the eastern batinah coastal plain of northern oman between 1995 and 1998 indicate two different principal water vapor sources for precipitation in the area a northern mediterranean source and a southern indian ocean source as a result two new local meteoric water lines were defined for the study area isotopic analyses of groundwater samples from over 200 springs and wells indicate that the main source of water to the batinah coastal alluvial aquifer is high altitude rainfall from the adjacent jabal akhdar mountains originating from a combination of northern and southern moisture sources the groundwater recharged at high altitude forms two plumes of water which is depleted in the heavy isotopes 18o and 2h and stretches from the mountains across the coastal plain to the sea thereby retaining a chemical homogeneity horizontally and vertically down to a depth exceeding 300 m in contrast in areas adjacent to these two plumes the alluvial aquifer is geochemically stratified near the coast saline intrusion results in abrupt changes in chloride concentrations and isotope values

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

deep infiltration through a sandy alluvial fan in semiarid niger inferred from electrical conductivity survey vadose zone chemistry and hydrological modelling abstract in semiarid southwestern niger most of the groundwater recharge is indirect and occurs through endoreic ponds elsewhere in the landscape there is no evidence of deep infiltration with a possible exception for gullies and alluvial fans on sandy slopes in order to verify this hypothesis a detailed geophysical and geochemical survey was conducted on a large representative mid slope fan 6 ha at this site distributed hydrological modelling conducted over the encompassing endoreic catchment 190 ha showed high losses of runoff water by infiltration electromagnetic mapping and 2 d electrical imaging survey were used to investigate the 35 m deep vadose zone in addition 8 boreholes were drilled following the geophysical survey to constrain the interpretation variations in apparent electrical conductivity measured in boreholes appear to be mainly linked with changes in the soil solution mineralization an extrapolation throughout the area shows that apparent electrical conductivity of the ground is systematically lower below channels this suggests localised leaching through the unsaturated zone a physically based 2 d distributed hydrologic model was used to estimate the amount of surface water loss by infiltration for the 1992 2002 period depending on year infiltrated volumes range from 1000 to 24 000 m3 this represents between 5 and 16 of the runoff that reaches the final outlet of the basin an endoreic valley bottom pond where recharge to the aquifer has been shown to occur because leaching of the vadose zone is observed down to a depth of 10 m below channels episodic groundwater recharge through sandy mid slope fans is highly probable during rainy years

basin geomorphological controls on the mechanism of recharge and discharge and its effect on salt storage and mobilization comparative study using geophysical surveys abstract downhole electromagnetic em profiles have been used to study the salt distribution in four catchments in the wheatbelt of western australia the good correlation r 2 0 7 0 9 obtained by relating the apparent conductivity profiles measured by the downhole em with salt profiles from soil cores enabled estimation of the salt storage in the uncored wells the salt distribution was compared with ground conductivity surveys using em31 and em34 instruments in three catchments and with an input aerial electromagnetic survey aem in a fourth catchment the study revealed the presence of five types of apparent electrical conductivity profiles eca which are correlated with the basin geomorphological units the conductivity profiles are 1 low eca recharge profile 2 subsurface peak discharge profile 3 two bulge profiles a single bulge accumulation weathering profile and a split aquifer development profile 4 reduced bulge leaching profile 5 high eca irregular palaeochannel profile the salt distribution showed a systematic increase in salinity from the watersheds to the valleys with salinity increasing upstream of geological structures the salt distribution was found to be controlled by the geomorphologic properties of the basins which control the hydrological and hydrogeological processes and by the recharge discharge mechanisms which influence salt mobilization and accumulation

handbook of environmental isotope geochemistry vol 1 the terrestrial environment a p fritz and j ch fontes editors elsevier amsterdam 1980 xii 532 pp u s 90 25 dfl 185 00

uncertainties in reservoir production forecasts being aware of uncertainties in forecasts of production characteristics is important for reservoir management decisions concerning further appraisal drilling flexibility in development plans and selection among reservoir prospects all require that uncertainties are taken into account this study addresses the problem of quantifying uncertainties due to incomplete knowledge of the initial reservoir characteristics with emphasis on the difference between heterogeneity modeling and assessment of uncertainty in this study we outline a formalism for uncertainty modeling in a bayesian framework and present an extensive case study of a north sea brent group reservoir the results are obtained by computer software implemented such that no human interference is required once the stochastic reservoir model is established once the stochastic reservoir model is established multiple realizations can be generated rescaled and fed into a fluid flow simulator to forecast production characteristics and quantify uncertainty associated with response parameters such as cumulative oil production recovery factors and water cuts the results demonstrate that uncertainty in model parameters contributes significantly to the overall uncertainty the most influential parameters in our case study include the sealing capacity of major faults seismic velocities used in depth conversion and average porosities and shale continuity within the main reservoir sandstone

filling the north european early middle eocene ypresian lutetian boundary gap insights from the pyrenean continental to deep marine record abstract the early middle eocene ypresian lutetian transition is represented by a hiatus in many north european sections including those in which the classic stratotypes were originally defined however the global stratotype section and point of the lutetian stage which is still pending definition should be placed at a globally correlatable event included within that unrepresented interval the pyrenean eocene outcrops display sedimentary successions that offer the rare opportunity to analyse the ypresian lutetian boundary interval in almost continuous sections and in very different settings seven reference stratigraphic sections were selected on the basis of their quality and correlated by means of biomagnetostratigraphic data this correlation framework casts light on the sequence of chronostratigraphic events that characterize the ypresian lutetian boundary interval which may prove useful in defining the main correlation criterion of the base of the lutetian all of the pyrenean sections show a similar sedimentary evolution despite being up to 350 km apart from each other containing deposits of different origins intrabasinal carbonate sediments siliciclastic sediments sourced from the iberian plate and terrigenous sediments sourced from the uplifting pyrenees and despite having been accumulated in different sedimentary environments from continental to deep marine and in different geodynamic settings piggy back basin foreland basin and cratonic margin this common evolution can be readily interpreted in terms of a sea level driven depositional sequence whose lowstand and transgressive systems tracts are included within the ypresian lutetian boundary interval the pyrenean ypresian lutetian depositional sequence can reasonably be correlated with depositional sequences from classic north european areas shedding light on the palaeoenvironmental history which in those areas has not been recorded furthermore these depositional sequences may possibly correlate with others from the antarctic ocean and from new jersey as well as with oceanic temperature variations suggesting that they might be the result of climatically driven glacioeustatic sea level changes should this hypothesis prove correct it would confirm previous suggestions that the onset of antarctic glaciations needs to be backshifted to the late ypresian at least

integrated global stratigraphy and geologic timescales with some future directions for stratigraphy in china abstract our knowledge of the history of our planet comes from deciphering the sedimentary record of biologic ecologic geochemical climatic physical and other systems using a vast array of tools and innovative techniques to synthesize these trends and events into a coherent global history requires six inter connected international efforts 1 documentation and access to major research reference sections including standardization of convenient and precise terminology for divisions of geologic time e g global boundary stratotype section and point gssps and within stage levels 2 inter calibration of these marine and terrestrial records both within and among different regions to compile a global integrated scale 3 improving and applying age models to understand cause effect relationships and rates of processes 4 public databases and syntheses 5 international efforts and centers and 6 earth systems geo education that emphases relationships among fields in addition to training in particular specializations in the past two decades the careful analysis of the sedimentary records in china s marine and terrestrial basins have enabled major leaps in our understanding of earth s history such as major excursions of the carbon cycle during the cambrian lethal temperature excursions in early triassic cretaceous evolution of birds and catastrophic impacts of large igneous eruptions china has provided more reference sections for the international definition of gssps than any other country it is vital to put those records from the china basins into a larger global context

the role of soil organic matter in the geochemical cycling of chloride and bromide abstract chloride to bromide ratios were determined for rainfall in western australia and groundwaters and surface waters from a number of catchments in western australia victoria and queensland the ratio in rainfall though showing a large short term scatter on average reflected the ratio in ocean water groundwaters and surface waters often showed characteristic differences in cl br presumably associated with the cycling of bromide through soil organic matter to prove this association it is shown that in the leachate of saturated small columns of soil the cl br ratio is governed by chloride and bromide released from decomposing organic matter on leaching the columns of soil the cl br weight ratio decreased rapidly from a high 300 reflecting rainfall to a low 10 reflecting the ratio of chlorine to bromine bound to soil organic matter

groundwater recharge and exploitative potential zone mapping using gis and god techniques two thirds of the total area of taiwan is mountainous terrain which is the main groundwater recharge source of the plains region this study assesses groundwater recharge and exploitative potential zone in the central division of the mountain areas of taiwan the middle reaches of the jhuoshuei river basin basic information from remote sensing and a satellite phantom is collected to set up the basic data maps using elevation formosa ii images the normalized difference vegetation index drainage distribution slope aspect ratio lineament distribution and land cover a geographical information system is used to integrate five contributing factors namely lithology land cover land use drainage slope and lineaments the criteria for the recharge potential assessment are established to demarcate the potential groundwater recharge zone finally the god rating system is adopted to evaluate the potential exploitation zone three main parameters are considered the groundwater occurrence the lithology of the overlying layers and the depth to groundwater the results show that the middle reaches of the chenyuland river have large potential exploitation zones due to its high rainfall recharge capacity regions west of the jhuoshuei river and the downstream regions of the chingshui river are medium potential exploitation zones because of their high infiltration rates and shallow groundwater levels

stratigraphy sedimentology chronology and palaeohydrology of quaternary lacustrine deposits at madigan gulf lake eyre south australia abstract madigan gulf is a large bay at the southern end of lake eyre north a major ephemerally flooded playa in arid central australia at the southwestern margin of a vast 1 300 000 km2 internal drainage basin the stratigraphy and chronology of the quaternary sequence in the gulf is described from 8 cores and a cliff exposure at the gulf margin a number of depositional environments are recognised and their distinctive sedimentary components are described facies recognised include deep and shallow water lacustrine environments dominated by surface water processes and dry or ephemerally flooded playa environments dominated by groundwater controlled processes sedimentary components include terrigenous clastics from river inflow and shoreline erosion carbonates of detrital inorganic or biological origin and gypsum and halite evaporites carbonates and gypsum evaporites precipitated within the basin are frequently reworked as clastic components the establishment of a preliminary chronology for the sequence by the application of thermoluminescence uranium thorium disequilibrium amino acid racemization and radiocarbon dating techniques has allowed a reconstruction of the last 130 ka of lake eyre palaeohydrology the wettest phase occurred during the last interglacial early in oxygen isotope stage 5 when an enlarged lake eyre was up to 25 m deep subsequently there has been a number of dry periods separating successively less effective wet phases culminating in the deposition of a substantial halite salt crust around the time of the glacial maximum the dry interludes are characterised by deflation of salts and sediment from the basin a process controlled by lowering of the watertable the record from madigan gulf demonstrates the dramatic and repetitive impact of lake deflation on the quaternary record of lake eyre in the early holocene a minor but mostly perennial lacustrine event was terminated at about 3 4 ka when the modern ephemeral playa regime was established the major catchment of lake eyre is located in the monsoon watered areas of northern australia as demonstrated by large floodings of the modern ephemeral regime major lacustrine episodes must indicate enhanced monsoon precipitation in northern australia in the holocene the lake has not risen to levels achieved during the early stage 5 lacustral phase indicating a marked reduction in the effectiveness of the monsoon in the present interglacial by comparison with its predecessor

hierarchical subdivision of the cenozoic era a venerable solution and a critique of current proposals abstract if tertiary and quaternary are to be formally defined and ranked then only one topology and two ranking options for the major subdivisions of the cenozoic era are consistent with the principles of hierarchical classification these are 1 for the tertiary and quaternary to be ranked as suberas with the paleogene and neogene ranked as periods of the tertiary or 2 for the tertiary and quaternary to be ranked as periods with the paleogene and neogene ranked as subperiods of the tertiary the first option would leave the period rank empty for quaternary time however so the second option is preferred here in neither case is an extension of the neogene to the present permitted if desired however early cenozoic and late cenozoic could be defined as formal unranked chrons with the latter term providing an unambiguous expression for the same concept as the extended neogene attempts to justify an extended neogene by reference to a statement arising from the 1948 international geological congress fail because they are based on a misinterpretation of that statement likewise an appeal to the alleged original meaning of the neogene fails because it is factually superficial and would also have unacceptable consequences if applied as a general principle to the rest of the time scale four arguments against a ranked tertiary and or quaternary involve the status of these names as parts of an obsolete classification the disparity in their durations an analogy between them and the unranked precambrian and their supposed ambiguity these arguments are readily refuted arguments in favor of a ranked tertiary and quaternary include the continuing widespread use of these names their practical relevance for geologic maps and their role in honoring the pioneers of stratigraphy a recent recommendation by the international commission on stratigraphy ics would decouple the beginning of the quaternary from the beginning of the pleistocene have the neogene and pliocene overlap the tertiary quaternary boundary and have the gelasian age belong to both the pliocene and the quaternary these results violate the existing guidelines of the ics this same proposal would also regard the quaternary as a subera within the neogene period the latter being extended to the present however this arrangement violates the most fundamental rule of hierarchical classification in that a unit of superior rank would be included entirely within a unit of inferior rank given these problems the international union of geological sciences iugs must reject the ics recommendation an improved version of the ics proposal with the quaternary ranked as a period and the paleogene and extended neogene ranked as suberas would still prohibit the tertiary from being ranked and would either violate simpson s rule or else require a new name for the traditional concept of the neogene because the classification of the cenozoic advocated here is strictly hierarchical violates none of the existing guidelines of the ics obeys simpson s rule requires no new names allows the tertiary quaternary paleogene and neogene to be formally ranked and has been in general use for more than a century it is to be preferred only two current options for defining the quaternary and pleistocene are valid namely to leave the beginnings of these units where they are now vrica gssp at 1 8 ma or to move both to the piacenzian gelasian boundary monte san nicola gssp at 2 6 ma the latter option is not prohibited by lyell s types of the older pliocene nor after 2008 by the existing guidelines of the ics but if enacted could jeopardize the stability of the rest of the standard global time scale

inventories and mobilization of unsaturated zone sulfate fluoride and chloride related to land use change in semiarid regions southwestern united states and australia 1 unsaturated zone salt reservoirs are potentially mobilized by increased groundwater recharge as semiarid lands are cultivated this study explores the amounts of pore water sulfate and fluoride relative to chloride in unsaturated zone profiles evaluates their sources estimates mobilization due to past land use change and assesses the impacts on groundwater quality inventories of water extractable chloride sulfate and fluoride were determined from borehole samples of soils and sediments collected beneath natural ecosystems n 4 nonirrigated rain fed croplands n 18 and irrigated croplands n 6 in the southwestern united states and in the murray basin australia natural ecosystems contain generally large sulfate inventories 7800 120 000 kg ha and lower fluoride inventories 630 3900 kg ha relative to chloride inventories 6600 41 000 kg ha order of magnitude higher chloride concentrations in precipitation and generally longer accumulation times result in much larger chloride inventories in the murray basin than in the southwestern united states atmospheric deposition during the current dry interglacial climatic regime accounts for most of the measured sulfate in both u s and australian regions fluoride inventories are greater than can be accounted for by atmospheric deposition in most cases suggesting that fluoride may accumulate across glacial interglacial climatic cycles chemical modeling indicates that fluorite controls fluoride mobility and suggests that water extractable fluoride may include some fluoride from mineral dissolution increased groundwater drainage recharge following land use change readily mobilized chloride sulfate displacement fronts matched or lagged chloride fronts by up to 4 m in contrast fluoride mobilization was minimal in all regions understanding linkages between salt inventories increased recharge and groundwater quality is important for quantifying impacts of anthropogenic activities on groundwater quality and is required for remediating salinity problems

constraining modern and historical recharge from bore hydrographs 3h 14c and chloride concentrations applications to dual porosity aquifers in dryland salinity areas murray basin australia summary water table fluctuations and renewal rates based on 3h and 14c concentrations in bores screened within 5 m of the water table were used to estimate recharge rates in five dryland salinity areas in northern victoria australia given the resolution of each technique both methods yield broadly similar results of 4 90 mm yr up to 14 of modern rainfall that reflect the recharge rates following land clearing over the last 200 years deeper bores show mixing of modern recharge with older water flowing laterally through the aquifers recharge estimates based on cl concentrations are up to two orders of magnitude lower

the hydrogen and oxygen isotopic composition of precipitation evaporated mine water and river water in montana usa summary the isotopic composition of 42 samples of rain and snow collected in 2004 were used to construct a local meteoric water line lmwl for butte montana the derived equation d 7 31 18 o 7 5 r 2 0 987 represents one of the first published lmwls based on direct precipitation for any location in the northern rocky mountains samples of underground and surface mine waters in butte including the berkeley pit lake and a nearby tailings pond define a linear trend with a much lower slope and intercept than the lmwl d 5 00 18 o 49 5 r 2 0 991 consistent with non equilibrium evaporation at an average relative humidity of roughly 65 detailed evaporation calculations are presented which indicate that the shallow berkeley pit lake was approximately 25 evaporated in october 2003 whereas the surface of the tailings pond was at least 50 evaporated the intersection of the lmwl and mine water evaporation trend was used to calculate the average composition of recharge water to the flooded mine complex d 139 18 o 18 0 these values are considerably lighter than the weighted total of precipitation for the 2004 calendar year d 118 18 o 15 3 which is partly explained by the unusually low snowfall that montana experienced in 2004 based on this study the lmwl recently proposed by kendall and coplen 2001 kendall c coplen t b 2001 distribution of oxygen 18 and deuterium in river waters across the united states hydrological processes 15 1363 1393 from regression of isotopic data from a number of montana rivers is more accurately interpreted as an evaporation line isotopic trends based on river data should be treated with caution particularly in a semi arid region such as montana where rivers are often influenced by dams and irrigation withdrawals

response of input and output of water and chloride to clearing for agriculture five small forested catchments in the collie river basin in southwest western australia were instrumented to quantify the changes in the input and output of salt and water when land use changed from forest to agriculture the paired catchment approach was used with two adjacent catchments located in high rainfall 1200 mm yr 1 and a group of three located in a lower 800 mm yr 1 rainfall area the treatment of complete clearing was applied to one catchment in the high rainfall zone and to about half of one catchment in the lower rainfall zone after three years of calibration with the uncleared control catchments strategies of partial clearing were applied to the third catchment in the lower rainfall zone the catchment pairs were found to be well matched the yield of water and salt increased immediately after clearing in the higher rainfall catchment streamflow increased about four times to 48 of rainfall salt load increased to fifteen times the mean saltfall measured as chloride ion of 7 g m 2 yr 1 direct runoff increased fourfold to 16 of yearly streamflow due partly to the progressive increase in the area of soil saturated to the surface the perched groundwater system was the major source 77 in 1983 of streamflow though it was the route rather than the source of increased salt to the stream the mottled and pallid clay profile was the dominant source of salt transported by the deep groundwater system into the perched aquifer streamflow became perennial in the first postclearing year absolute increases in streamwater and salt output from partially cleared catchments in the lower rainfall location were about an order of magnitude less than for the higher rainfall catchment though the relative increases were similar the three catchments were found to be accumulating salt in the cleared catchments the rising potentiometric surface would establish a saline groundwater discharge zone in the valley and a net export of salt in all treated catchments reduced interception results in increased water availability at the soil surface for stormflow and infiltration the reduction in transpiration had an added effect in increasing recharge to groundwater a new equlibrium for water had not been achieved eight years after clearing but was estimated to precede the new salt equilibrium

origin of the high variability of water mineral content in the bedrock aquifers of southern madagascar this study assesses the causes of the high spatial variability of the mineral content of groundwater in crystalline bedrock of southern madagascar although many kilometres from the coast and at a mean altitude of 400 m a s l wells drilled in this area produce water with electrical conductivities in the range of 300 30 000 mu s cm 1 with a high spatial variability chemical and isotopic data are used to identify the processes involved in the groundwater mineralization it is shown that the chemical composition of the groundwater in this region has its origin in i normal silicate and carbonate weathering reactions and ii input of marine salts probably via rainfall recharge modified by evapo concentrative processes probably including precipitation and re dissolution of secondary evaporites in the unsaturated zone to obtain a better understanding of the spatial salinity distribution well parameters such as yields weathered zone thickness weathered materials and morphological positions upper slope mid slope lower slope or valley bottom are scrutinized a correlation was found between high salinity and low flow shallow groundwater environments flat hill tops valley bottoms weakly developed and clayey weathered zones and between low salinity and high flow environments granular well developed weathered zones and situation on valley slopes

notes on geochronologic and chronostratigraphic units there is no need to regard the term geochronology as a redundant synonym of either geologic time scale or radiometric dating this term may reasonably be used in reference to all principles and methods employed in geology to determine the relative and numerical ages of all kinds of rocks the term chronostratigraphy would best be restricted to the process of defining the formal subdivisions of the geologic time scale geochronologic unit is best used as a general category term it includes aurichronologic units spans of time defined operationally by golden spikes geochronometric units spans of time defined theoretically in terms of absolute numerical age before present and biochronologic units spans of time defined theoretically by paleobiological events a chronostratigraphic unit is a set of material existing stratified rock that was formed during a given span of time geochronologic unit therefore a geochronologic unit must be defined before the corresponding chronostratigraphic unit can even be conceptualized chronostratigraphic units are generally not isochronous bodies of rock because owing to the unconformities that exist over any appreciable geographic area their upper and lower material boundaries are not everywhere synchronous thus particular systems series and stages are material stratigraphic units of geographically variable time value within the maximum temporal limits of the corresponding periods epochs and ages geochronologic boundaries that have been formally ratified serve a conventional function and will rarely if ever need to be redefined we can continue to discover and debate important events in earth history without insisting that such events must be used to constantly redefine the boundaries of our global temporal pigeonholes

gssps global stratigraphy and correlation procedures used to define an international chronostratigraphic stage boundary and to locate and ratify a global boundary stratotype section and point gssp are outlined a majority of current gssps use biostratigraphic data as primary markers with no reference to any physico chemical markers despite the international subcommission on stratigraphic classification issc suggestion that such markers should be included if possible it is argued that such definitions will not produce the high precision phanerozoic time scale necessary to understand such phenomena as pre pleistocene ice ages and global climate change it is strongly recommended that all gssps should have physico chemical markers as an integral part of their guiding criteria and where such markers cannot be found the gssp should be relocated the methods and approach embodied in oceanic stratigraphy coring logging analysing and archiving of drill sites by numerous experts using a wide range of methods could usefully serve as a scientific model for the analysis and archiving of gssps all of which are on the present day continents the incorporation of many more stratigraphic sections into gssp studies the application of physico chemical methods and the replacement of old u pb dates by newer ca tims u pb dates together with the use of constrained optimization conop programs that produce a calendar of events from many sections should lead to much more precise timescales for pre cenozoic time than are currently available

sedimentology and shale modeling of a sandstone rich fluvial reservoir upper statfjord formation statfjord field northern north sea sandstone rich fluvial reservoirs of the upper part of the statfjord formation in statfjord field northern north sea include significant proportions of interstratified shale beds which complicate the production of oil under a high pressure miscible gas flood flood plain mudstones characterized by pedogenic alteration and finely laminated abandoned channel facies form the most important flow barriers mudstones deposited in flood plains are expected to have a greater lateral continuity than those deposited in abandoned channels fluctuations in allogenic factors such as base level and sediment supply rates have led to a variable preservation of the mudstones this combination of different facies types and fluctuating allogenic control has led to a complex barrier dist ibution within the reservoir which is difficult to describe using conventional mapping techniques a procedure based on two stochastic simulation techniques has been adopted in order to model the complex barrier distribution a two dimensional markov field model is used as an alternative to conventional shale mapping to describe the distribution of shale beds that are correlated between two or more wells the model is based on probabilistic estimations of shale continuity between well pairs and allows the simulation of local channel incision through otherwise extensive shale beds a marked point process model is adopted to describe the distribution of smaller scale discontinuous barriers within the reservoir sand bodies it is based on probabilistic estimations of shale dimensions defined using cumulative frequency distributions the stochastic modeling procedure allows greater flexibility to include a variety of geological interpretations and assumptions in the heterogeneity model and the increased geological input results in more realistic models of communication between and vertical permeability within the reservoir sand bodies

challenges in defining the base of cambrian series 2 and stage 3 formal subdivision of the cambrian system into four series and ten stages is in progress the base of cambrian stage 3 provisional which is conterminous with the base of cambrian series 2 provisional is expected to be placed at a horizon close to the first appearance of trilobites which marks the onset of the largest phase of the cambrian explosion conceptually an ideal boundary position would be marked by a significant and globally recognizable bioevent that divides the lower part of the cambrian system into a sub trilobitic terreneuvian series and a trilobite dominated series 2 if the level is to be identified principally through biostratigraphic means its position also needs to be recognizable using non biostratigraphic means and its correlation potential should be tested through detailed investigation of several continuous successions embracing the critical interval major difficulties in identifying a suitable horizon include strong biotic provincialism a plethora of regional unconformities and facies changes on different paleocontinents in the cambrian terreneuvian series 2 boundary interval levels that provide potential for intercontinental correlation include the first appearance position of trilobites and the approximately equivalent first appearance positions of certain small shelly fossil and acritarch species in addition a non biostratigraphic marker such as a stable carbon isotopic excursion may be useful as a correlation level cambrian series 2 and stage 3 are provisional stratigraphic units and their conterminous base was previously suggested to coincide to the appearance of trilobites compared to other potential chronostratigraphic indicators the first appearance of trilobites still has advantages for recognizing and correlating the base of stage 3 and should remain as the provisional primary marker for the boundary position

the application of high resolution sequence stratigraphy to fluvial systems a case study from the upper carboniferous breathitt group eastern kentucky usa the pennsylvanian pikeville hyden and four corners formations of the breathitt group in eastern kentucky usa contain six major facies associations along with a number of subassociations these facies associations are offshore siltstone rhythmically bedded mouthbar heteroliths predominantly fine grained floodplain deposits minor channel fills major distributary channels and major stacked fluvial bodies the stacked fluvial bodies are incised into a variety of open marine and delta plain deposits have widths of several kilometres and exhibit a range of sandy fill types these fluvial complexes are interpreted as incised valley fills parasequences and parasequence sets are not identifiable nonetheless it is possible to identify systems tracts on the basis of sequential position facies associations and systematic changes in architectural style and sediment body geometries the studied portion of the breathitt group comprises stacked 4th order sequences which occur in lowstand transgressive and highstand sequence sets related to the development of a lower frequency base level cycle in the lowstand sequence set incision associated with successive 4th order sequence boundaries has commonly removed all the hst and tst of the underlying sequences such that succeeding 4th order incised valley fills are amalgamated within the transgressive sequence set incision is at a minimum and incised valley fills tend to stack discretely with the maximum amount of fine grained tst and hst between them the highstand sequence set is transitional between the lowstand and transgressive sequence sets in terms of the amount of transgressive and highstand deposits preserved incised valley fills tend to stack discretely

more evidence that the chicxulub impact predates the k t mass extinction yaxcopoil 1 yax 1 drilled within the chicxulub crater was expected to yield the final proof that this impact occurred precisely 65 myr ago and caused the mass extinction at the cretaceous tertiary k t boundary instead contrary evidence was discovered based on five independent proxies sedimentologic biostratigraphic magnetostratigraphic stable isotopic and iridium that revealed that the chicxulub impact predates the k t boundary by about 300 000 years and could not have caused the mass extinction this is demonstrated by the presence of five bioturbated glauconite layers and planktic foraminiferal assemblages of the latest maastrichtian zone cf1 and is corroborated by magnetostratigraphic chron 29r and characteristic late maastrichtian stable isotope signals these results were first presented in keller et al 2004 in this study we present more detailed evidence of the presence of late maastrichtian planktic foraminifera sedimentologic and mineralogic analyses that demonstrate that the chicxulub impact breccia predates the k t boundary and that the sediments between the breccia and the k t boundary were deposited in a normal marine environment during the last 300 000 years of the cretaceous

chronostratigraphic correlations their importance for the definition of geochronologic units abstract the present article resumes the philosophy underlying the re definition of chronostratigraphic geochronologic units through their boundaries by working groups of the international commission on stratigraphy ics following the ics guidelines with respect to the historical approach this philosophy implies a change in the way how stages are defined stages originally defined by their contents are now defined by their lower boundary only the concept of the global stratotype standard section and point gssp as before stages may be characterized by their contents but precise definitions of stages and their scope can only be attained via boundary definitions the following subjects are dealt with in detail 1 the choice of the level of a chronostratigraphic geochronologic boundary which is to be defined by a gssp this is determined by practical considerations concerning the correlation of the envisaged stratigraphic level 2 if traditional names are to be preserved some kind of compromise is always necessary because none of them is clearly and unequivocally defined this goal can be attained by a democratic vote 3 because of gaps and condensation even the more favorable historical stratotypes are unsuitable for the redefinition of classical stages by their lower boundaries

past changes to isotopic and solute balances in a continental playa clues from stable isotopes of lacustrine carbonates in many salt lakes around the world the relative abundance of preserved authigenic minerals is different from that predicted from solute mass balance calculations conventional mass balance models assume that chloride behaves conservatively over long periods of time and fail to take into account the role of diffusion deflation and fractional crystallisation dissolution of salts an alternative approach is to use oxygen isotopes as these reflect directly water molecule rather than solute concentrations and have the added advantage of providing a palaeohydrological record in lacustrine carbonates we present a steady state stable isotope model in conjunction with stable isotopic measurements of sub surface brines regional groundwaters and carbonate deposits from the lake malata lake greenly playa complex in south australia to estimate the apparent leakage and palaeoleakage from these superficially closed playa lakes the steady state model calculations using the present and compositions of the lake brines and inflowing groundwater suggest that the apparent present day leakage for the complex is 75 to 90 of inflow 35 times that calculated from cl and br under such conditions only low magnesian calcite precipitates and the lake water experiences reduced effects of evaporation gas and vapour exchange and consequently reduced isotopic and chemical enrichment further our model shows that calcite becomes increasingly mg rich until leakage is reduced to 55 to 70 of inflow a condition favourable for dolomitisation and of the lacustrine carbonates show excursions on the order of 5 over the length of a 2 3 m core indicating that the lake complex has varied from being throughflow dominated presence of low mg calcite relatively depleted in and to evaporation dominated high mg calcite dolomite relatively enriched in and throughout late quaternary our estimates of leakage fractions are consistent with the observed mineralogical suite but there remains a discrepancy between apparent closure indicated by the presence of the highly saline brine reservoir 1 leakage and high rates of throughflow inferred from stable isotope data we propose that the brine was formed by winter time re solution of a seasonal halite crust which forms during summer dominated evaporative discharge recirculation of the secondary brine and mixing with regional groundwater may decouple the solute cycle from the water cycle in many playa lakes the end result is a partially mixed brine characterised by nearly conserved solutes but with isotopic signatures indicative of brine rainfall groundwater interactions

drawing a line in the sand identifying and characterizing boundaries in the geological record the identification and characterization of boundaries is a fundamental activity in geoscience spatial and temporal boundaries are rarely sharp but are more usually zones of transition which may have variable characteristics the examination of palynological and micropalaeontological data is often crucial for the delineation of geological boundaries especially for the definition of global boundary stratotype sections and points gssps the sixteen papers in this volume highlight many productive methodological approaches to boundary identification this essay reviews the theoretical background to boundary identification in geology and provides the contextual perspective for the subsequent papers much of geoscience has to do with classification of organisms of rocks or of processes inevitably classification devolves into an exercise in drawing boundaries putting a limit on what is included and what is not in the geological record this exercise takes place in three dimensions with space and time interacting to produce a plethora of boundaries and boundary definitions although conventionally on stratigraphic charts for example temporal boundaries are often shown as sharp lines in reality they are rarely so similarly spatial boundaries on maps are seldom as abrupt as they are drawn process boundaries are yet more subtle and usually less clear indeed even to speak of a boundary is contentious since boundaries come in many forms and types boundaries are more often intervals or spaces of transition leaving plenty of room for argument over their placement perhaps for this reason some of the more truculent and long lasting debates in geology have been over the positioning and identification of boundaries drawing a line in the sand may seem a simple exercise but turns out to be fraught with complexities boundary definitions in geoscience the criteria for identifying chronostratigraphic biostratigraphic and lithostratigraphic units are outlined in rules set up by international agreement such as the international stratigraphic guide salvador 1994 or guidelines such as the north american stratigraphic code north american commission on stratigraphic nomenclature 1983 or the stratigraphic procedure rawson et al 2002 the demarcation of boundaries is generally a consequence of the identification of units rather than the other way round historically the identification of boundaries has often arisen from the practical exigencies of geological mapping the need to produce visual representations of geology primarily based on sections or surface exposures boundaries therefore were often synonymous with the limits of mappable units that were generally field identified on the basis of lithology this approach gave rise to the designation of body stratotypes a methodology that proved limiting for the subdivision of geological time because of gaps in the rock record harland et al 1990 modern geochronology emphasizes boundaries especially lower stage boundaries rather than units as fundamental for subdivision and correlation remane 2003 under the auspices of the international commission on stratigraphy ics various subcommissions have been established to examine the placement of particularly critical temporal boundaries in the geological record see list in gradstein ogg 2003 considerable effort has been devoted to the establishment of global boundary stratotype sections and points gssps with more than 40 defined so far gradstein et al undated for each boundary a type section and a specific 3b2 version number 7 51a w may 2 2001 jobsin m11251 00c geo introduction 3d date 27 10 04 time 11 48am page 1 of 10 m11251 the geological society tradespools frome somerset from beaudoin a b head m j eds 2004 the palynology and micropalaeontology of boundaries geological society london special publications 230 1 10 0305 8719 04 15 the geological society of

environmental isotope hydrology of salinized experimental catchments deuterium oxygen 18 tritium and chloride concentrations were used in three salinized experimental catchments to gain insight into the mechanism of solute concentration and flow processes in the saturated and unsaturated zones the three experimental catchments were studied because of their location in different rainfall regions their status with respect to clearing of native vegetation and with respect to secondary salinization two uncleared catchments have average annual rainfalls of approximately 820 and 1220 mm respectively the third cleared catchment has an annual rainfall of 650 750 mm this catchment was in an advanced state of secondary salinization and displayed large areas of saline groundwater discharge with halite encrustation at the ground surface the stable isotope compositions of the solution phase in solute bulge profiles in the unsaturated zone showed a close agreement with the amount weighted mean isotopic composition of rainfall and only surficial evidence of isotopic enrichment due to evaporation evaporation from the soil surface plays a minor role as a mechanism of solute concentration in the unsaturated zone the dominant process of solute concentration in the unsaturated zone was ion exclusion during uptake of water by tree roots which was evidently a solute but not isotope fractionating process tritium analyses of unsaturated zone water and grondwater indicated movement of recent recharge to 7 10 m depth at the low rainfall site but over the full depth of the 15 m unsaturated zone at the higher rainfall site the variability in 18o and 2h values of groundwaters was used in association with chloride concentrations to provide information on mixing characteristics of groundwaters within the catchments

estimation of groundwater recharge in sandy till with two different methods using groundwater level fluctuations abstract two methods for estimation of groundwater recharge both based on groundwater level fluctuations were applied in a moraine area in southeastern sweden the first method utilized a onedimensional soil water model which was tested against observed groundwater levels the boundary conditions were defined by using standard meteorological data and submodels for precipitation snow dynamics interception evapotranspiration and horizontal groundwater outflow the second method directly transformed groundwater level fluctuations to equivalent amounts of water from a constructed recession curve and the specific yield concept conceptually the two methods could be characterized as inflow and response methods respectively a good fit between observed and simulated groundwater levels was obtained by the soil water modelling the results were however shown to be rather insensitive to displacement in the water balance between evapotranspiration and groundwater outflow giving a good fit for a simulated net groundwater recharge ranging between 134 and 197 mm the results from the attempts to use groundwater level fluctuations directly were discouraging compared to the soil water simulations the results were unstable and quite different for different years it was impossible to use a constant specific yield or even different specific yields depending on depth the conclusion was that the possibilities to use groundwater level data for quantitative water balance studies are limited under the studied climatical and hydrogeological conditions the modelling effort clearly demonstrated the need for a better quantitative knowledge on soil properties if water balance information is to be deduced the soil water model though could be a valuable tool studying variations within and between different years as well as processes and single events

the stratigraphic status of the anthropocene the term anthropocene was coined to describe the present geological epoch in which human activity dominates many of the processes acting on the surface of the earth the expression has been widely adopted but remains informal and lacks precise definition there have been several attempts to establish formal stratigraphic markers to define the start of the anthropocene most recently certini and scalenghe certini g and scalenghe r 2011 anthropogenic soils are the golden spikes for the anthropocene the holocene 21 1269 1274 have argued that the best markers are anthropogenic soils and that these may be used to identify the base of the anthropocene in stratigraphic sequences unfortunately soils fail to meet many of the criteria required for the establishment of stratigraphic golden spikes their preservation potential is poor many stratigraphically important environments do not experience pedogenesis and anthrosols do not always provide the stratigraphically lowest marker of human impact in ad

identification of areas of recharge and discharge using landsat tm satellite imagery and aerial photography mapping techniques abstract aerial photographs ap and landsat tm colour composites were used to map the geomorphology geology and structures of the salt river system of western australia geomorphic features identified are sand plains dissected etchplain colluvium lateritic duricrust and rock outcrops the hydrogeomorphic units include streams lakes and playas palaeochannels and palaeodeltas the structural features are linear and curvilinear lineaments ring structures and dolerite dykes suture lines control the course of the main river channel permeable areas around the circular granitic plutons were found to be the main areas of recharge in the uplands recharge was also found to occur in the highly permeable areas of the sandplains discharge was shown to be primarily along the main drainage lines on the edge of the circular sandplains in depressions and in lakes the groundwater occurrence and hydrogeological classification of the recharge potential of the different units were used to classify the mapped areas into recharge and discharge zones the results also show that tm colour composites provide a viable source of data comparable with ap for mapping and delineating areas of recharge and discharge on a regional scale

modelling streamflow in a large anastomosing river of the arid zone diamantina river australia anastomosing rivers form a subset of the anabranching family of river types and provide considerable challenges to modelling of their streamflow because of complex flow patterns across greatly varying floodplain widths estimates of distributed flow data are required for catchment management purposes and ecological studies of these rivers but are hindered by a paucity of measured discharge data a grid based semi distributed conceptual model structure is applied to a 330 km reach of the arid zone diamantina river of central australia model complexity is constrained by data availability with only a single gauging station located at the downstream end of the reach to provide discharge data for model calibration the model uses a simple conceptual bucket structure and accounts for exceptionally high transmission losses as well as flow patterns and wave speeds that vary with discharge within the reach the intricate flow patterns across the floodplains widths of up to 50 km are simulated using a grid based structure that required the following features i cell connections that are explicitly defined using a code that allows for multi directional flow from a cell and ii each cell having a binary flow pattern with the second connection pattern being triggered when the surface storage of the cell exceeds a calibrated level for a given land type satellite images were used to define the flow paths and hence cell connection patterns utilised by various sized floods the model was able to provide acceptable simulation of large floods but with decreasing model performance in the simulation of small to medium sized floods simulation suggested that incorrectly defined flow paths for the smaller floods were a major factor in this decreased performance the capability of the model would be improved by further detailed mapping using satellite imagery of spatial patterns of inundation as discharge varies

cl br ratios and environmental isotopes as indicators of recharge variability and groundwater flow an example from the southeast murray basin australia abstract systematic variations in cl br ratios together with r 36 cl values 14 c activities and 18 o values reflect differences in groundwater recharge and define groundwater flow paths in the riverine province of the southeast murray basin in groundwater from the shallowest shepparton formation homogenisation of cl br and 18 o values and a decline in 14 c activities with depth imply that vertical flow dominates the 14 c activities define variations in pre land clearing recharge in the palaeovalleys of present day rivers deep leads which contain sandier sediments higher recharge 0 5 to 1 4 mm year produced relatively fresh groundwater tds 36 cl values in groundwater from the goulburn subcatchment zones of groundwater with variable cl br ratios in the deeper calivil renmark aquifer also allow the detection of rapid leakage from the surface that has the potential to compromise groundwater resources

perspectives on the sequence stratigraphy of continental strata this report is the result of a working group on continental sequence stratigraphy that was set up at the 1991 nuna conference in banff canada to date sequence stratigraphic concepts have been applied mainly to the marine realm but unconformity bounded units have long been recognized in nonmarine strata successful application of sequence stratigraphic concepts to continental strata requires careful consideration of controls on base level and sediment supply as with shallow marine environments relative sea level can be considered as the stratigraphic as well as the geomorphic base level for coastal nonmarine settings farther inland stratigraphic base level which determines accommodation space is more complex and takes various forms such as the graded profile for fluvial strata groundwater tables for some eolian strata and lake level for some intermontane sediments sediment supply is also generally a more complex variable for nonmarine environments than in the marine realm because of the proximity to the source area the influence of climate and tectonism on sediment supply can clearly be seen in many continental sediments the fact that the major controls of climate tectonism and eustasy are somewhat interdependent and that a change in one parameter will most likely be reflected in others is also more readily apparent in continental strata although in its infancy sequence stratigraphic concepts have been applied to a wide variety of continental settings in attempts to explain variations in facies architecture of particular interest are studies that have linked fluvial architecture on coastal plains to variations in relative sea level as indicated by coeval marine strata and studies of lacustrine environments that show marked variation in facies between highstand and lowstand deposits the application of sequence stratigraphy to continental strata will likely result in the development of better correlation techniques and models that better predict the location and nature of fluvial and eolian reservoirs

evaluation of multiple environmental factors for site specific groundwater recharge structures in the vaigai river upper basin tamil nadu india using gis based weighted overlay analysis the present study investigates the groundwater recharge potential zone and suitable sites for artificial recharge structures in the river vaigai upper basin theni district tamil nadu using gis based multi parameter weighted overlay method the study area experiences severe groundwater scarcity despite having high rainfall and runoff therefore an integrated remote sensing and gis technique is used to assess the permeability and infiltration characteristics of the area and demarcate the recharge potential zones the recharge potential zones and site specific artificial recharge structures have been demarcated based on the weights of multiple parameters based on their permeability and infiltration capacity to groundwater recharge the groundwater recharge potential map shows the twenty suitable sites for artificial recharge structures such as percolation ponds loose rock check dams and water absorption trench wat in various parts of the study area the effective recharge practices such as percolation ponds and check dams are highly suitable for gentle sloped barren and agricultural plains in the northwestern and northeastern parts whereas the barren valley fill bajada and streams intersecting lineaments along the middle eastern and central part are suitable for constructing wat and check dams these water harvesting features can improve the groundwater scenario of the study area and groundwater augmentation is possible in future with the help of advanced techniques like remote sensing and gis

stochastic modeling of incised valley geometries a stochastic modeling procedure designed to capture sequence stratigraphic principles has been developed for modeling fluvial reservoirs where high frequency base level fluctuations have exerted a strong influence on reservoir architecture reservoir stratigraphy and architecture are defined by the successive simulation of two types of surfaces base level rise flooding surfaces and base level fall surfaces sequence boundaries the flooding surfaces are modeled as standard two dimensional gaussian fields modeling sequence boundaries with incised valleys is more complex and required the development of a novel object modeling technique this new model can be used to generate realistic valley geometries and is flexible enough to allow for complex multiwell conditioning the modeling procedure is illustrated using a test data set based on well interpretations from the fluvial statfjord formation in the statfjord field of the norwegian north sea the main reservoir sandstones were deposited in valleys defined by a sequence boundary at the base and a flooding surface at the top whereas the main barriers to flow are mudstone rich intervals deposited on unconfined alluvial plains five sequence boundaries and four flooding surfaces have been interpreted within an approximately 60 m thick reservoir interval simulation of these surfaces using the new modeling procedure defines the three dimensional distribution of reservoir units and barriers the modeling procedure allows the simulation of realistic geometries that are in accordance with the geologist s conceptual model for the reservoir the models also provide an enhanced description of reservoir distribution and connectivity and can serve as an improved basis for reservoir management well placement and predictions of reservoir performance in complex fluvial reservoirs

carbonate platform growth and cyclicity at a terminal proterozoic passive margin infra krol formation and krol group lesser himalaya india the infra krol formation and overlying krol group constitute a thick 2 km carbonate rich succession of terminal proterozoic age that crops out in a series of doubly plunging synclines in the lesser himalaya of northern india the rocks include 18 carbonate and siliciclastic facies which are grouped into eight facies associations 1 deep subtidal 2 shallow subtidal 3 sand shoal 4 peritidal carbonate complex 5 lagoonal 6 peritidal siliciclastic carbonate 7 incised valley fill and 8 karstic fill the stromatolite rich peritidal complex appears to have occupied a location seaward of a broad lagoon an arrangement reminiscent of many phanerozoic and proterozoic platforms growth of this complex was accretionary to progradational in response to changes in siliciclastic influx from the south eastern side of the lagoon metre scale cycles tend to be laterally discontinuous and are interpreted as mainly autogenic variations in the number of both sets of cycles and component metre scale cycles across the platform may result from differential subsidence of the interpreted passive margin apparently non cyclic intervals with shallow water features may indicate facies migration that was limited compared with the dimensions of facies belts correlation of these facies associations in a sequence stratigraphic framework suggests that the infra krol formation and krol group represent a north to north westfacing platform with a morphology that evolved from a siliciclastic ramp to carbonate ramp to peritidal rimmed shelf and finally to open shelf this interpretation differs significantly from the published scheme of a basin centred on the lesser himalaya with virtually the entire infra krol krol succession representing sedimentation in a persistent tidal flat environment this study provides a detailed neoproterozoic depositional history of northern india from rift basin to passive margin and predicts that genetically related neoproterozoic deposits if they are present in the high himalaya are composed mainly of slope basinal facies characterized by fine grained siliciclastic and detrital carbonate rocks lithologically different from those of the lesser himalaya

geochemical and hydrological processes controlling groundwater salinity of a large inland wetland of northwest australia abstract understanding mechanisms of hydrochemical evolution of groundwater under saline and brine wetlands in arid and semiarid regions is necessary to assess how groundwater extraction or injection in large scale basins may affect the natural interface between saline fresh aquifers in those systems we investigated the evolution of groundwater of the fortescue marsh a large inland wetland of northwest australia that is mainly supplied by floodwater from the upper fortescue river catchment the marsh is located in the pilbara region one of the world s major iron ore provinces where mining activities often occur below water tables here we quantified the stable isotope and chemical composition of groundwater surface water and rainfall in and around the marsh to better understand how saline marshes and playa lakes function geochemically hydrologically and ecologically the deep groundwater 50 m depth of the fortescue marsh is highly saline 100 g l 1 whilst shallow groundwater 0 20 m depth and surface water are mainly fresh or brackish currently the marsh is mainly recharged by occasional floodwater consequently salt in the marsh is concentrated by evaporation of rainfall we expected that the hydrochemical composition of surface and groundwater would therefore reflect the chemical composition of rainwater we analysed 206 water samples for stable isotope composition 2 h 18 o and water chemistry including ph dissolved oxygen electrical conductivity ec and total dissolved solids tds as well as na ca mg k si fe hco 3 so 4 cl sr and br we then developed geochemical models and a salt inventory to estimate the geological time of salt accumulation and to decouple geochemical characteristics of salt from modern groundwater we found that groundwater associated with the marsh can be divided into two distinct groups that are characterised by their stable isotope compositions i fresh and brackish groundwater tds 1 18 o 8 0 0 9 and ii saline and brine groundwater tds 10 g l 1 18 o varies from 2 5 to 7 2 fresh groundwater was evaporated by

groundwater dating by estimation of groundwater flow velocity and dissolved 4he accumulation rate calibrated by 36cl in the great artesian basin australia abstract we tested two methods for dating groundwaters that cannot be reliably measured by 36cl dating alone one based on groundwater flow velocity plus distance along a flow path and the other based on 4he accumulation rates calibrated with 36cl dates we sampled groundwaters along six inferred regional groundwater flow paths in the great artesian basin gab of australia we selected three groundwater paths where the decrease in 36cl was largely controlled by cosmogenic 36cl radioactive decay without a significant increase in chloride concentration the extrapolated groundwater velocities were 0 133 0 018 m y to 0 433 0 140 m y the estimated residence time of 1 06 106 y at the discharge area around lake eyre was comparable to the estimate of 1 2 2 106 y in previous studies on the other hand our estimated 4he accumulation rates for the selected three groundwater flow paths 1 85 0 31 10 11 to 1 51 0 63 10 10 ccstp cm3 y were approximately 2 15 times lower than previously reported rates for the central gab our estimated rate of 1 51 10 10 ccstp cm3 y 1 in the western gab is compatible with previous estimates based on 81kr ages the groundwater residence time estimated from the 4he accumulation rate was approximately 7 105 y near the discharge area at lake eyre finally both estimations were mutually compatible with a 30 error

atmospheric bromine flux from the coastal abu dhabi sabkhat a ground water mass balance investigation 1 a solute mass balance study of ground water of the 3000 km2 coastal sabkhat salt flats of the emirate of abu dhabi united arab emirates documents an annual bromide loss of approximately 255 metric tons 0 0032 gmoles or 85 kg km2 this value is an order of magnitude greater than previously published direct measurements from the atmosphere over an evaporative environment of a salar in bolivia laboratory evidence consistent with published reports suggests that this loss is by vapor transport to the atmosphere if this bromine flux to the atmosphere is representative of the total earth area of active salt flats then it is a significant and generally under recognized input to the global atmospheric bromide flux

freshwater recharge into a shallow saline groundwater system cooper creek floodplain queensland australia freshwater lenses have been identified as having penetrated the shallow regional saline groundwater beneath the cooper creek floodplain near ballera south west queensland piezometers were installed to evaluate the major element chemistry along a floodplain transect from a major waterhole goonbabinna to a smaller waterhole chookoo associated with a sand dune complex the floodplain consists of 2 7m of impermeable mud underlain by unconsolidated fluvial sands with a saline watertable waterholes have in places scoured into the floodplain the transect reveals that groundwater recharge takes place through the base of the waterholes at times of flood scour but not through the floodplain mud total dissolved solids rise with distance from the waterhole and independently of the presence of sand dunes stable water isotopes 2h and 18o confirm that recharge is consistent with and dependant on monsoonal flooding events following floods the waterholes self seal and retain water for extended periods with sulfate 34s and 18o isotopes suggesting bacterial reduction processes within the hyporheic zone and limited interaction between the surface water and groundwater during no flow conditions the area occupied by the freshwater lenses tds 5000 mg l is locally asymmetrical with respect to the channel flow direction extending down gradient along distances of 300 m