a multi proxy record of holocene climatic change in southwestern spain the laguna de medina cadiz palaeolimnological data diatoms ostracods foraminifera molluscs aquatic pollen and lithology from a radiocarbon dated sediment core from a saline lake the laguna de medina provide the first complete record of holocene lake level change for southwest spain for the last c 9000 cal years the lake has always been relatively shallow but has exhibited marked fluctuations in salinity and water depth especially in the earlier record when oscillations culminate in maximum lake levels from c 6960 6680 cal bp c 6070 5830 bp indicating enhanced early to mid holocene humidity and a mid holocene humidity maximum prolonged shallowing thereafter reflects in part increased aridity in the later holocene lake desiccation followed by a c 800 yr phase zone 2 of major limnological change commencing at c 8000 cal bp c 7200 bp and a number of other abrupt desiccation events are also noteworthy the mid holocene maximum is consistent with widespread evidence for high lake levels around 6000 bp but t

glacial recharge and paleohydrologic flow systems in the illinois basin evidence from chemistry of ordovician carbonate galena formation waters the illinois basin provides an opportune setting for elucidating the roles of remnant evaporite brines and meteoric waters in the evolution of formation waters in an intracratonic sedimentary basin formation waters from carbonate reservoirs in the upper ordovician galena group have been analyzed geochemically to study the origin of their salinity their chemical and isotopic evolution and their relationship to paleohydrologic flow systems chloride bromide ratios and ci br na br relations indicate that initial brine salinity resulted from subaerial evaporation of seawater rather than from halite dissolution subsequent subsurface dilution of the brines by meteoric waters is disclosed by d 18 o covariance however the remnant evaporite brine has not been completely expelled from these ordovician strata galena formation waters have 87 sr 86 sr ratios that range from 0 708 17 a value nearly equal to that of coeval seawater to 0 710 43 this is the greatest range of sr isotopic ratios found in waters from any stratigraphic unit in the basin two fluid mixing events are revealed in plots of 87 sr 86 sr vs 1 sr introduction of 87 sr enriched fluids from a siliciclastic source probably overlying maquoketa shale and a later event that only affected reservoir waters in the western shelf of the basin general covariance between sr and h o isotopes suggests that the later event is related to meteoric water recharge the point of intersection of the d 18 o trend with the meteoric water line implies that this mixing event involved pleistocene glacial meltwater that recharged galena reservoirs near outcrops along the western margin of the basin ordovician galena formation waters are geochemically distinct from those in both silurian devonian and mississippian pennsylvanian strata a distinction that has evidently been maintained by the overlying maquoketa regional aquitard

137cs and 210pb dating of sediments from soft water lakes in new england u s a and scandinavia a failure of 137cs dating abstract deep water sediment cores from 32 scandinavian and 19 northern new england u s a lakes were analyzed for 137cs 210pb was analyzed in cores from 16 and 14 of these lakes respectively additional dating of the new england cores was based on chronostratigraphic pollen markers the profiles in sediment of 137cs deviate greatly from expectations based on fallout history the profiles have their maxima at the surface and 137cs occurs at depths dated by 210pb and pollen as many decades older than the beginning of 137cs fallout non exponential 210pb profiles in certain lakes most in new england and pollen dates suggest that bioturbation physical mixing changes in sedimentation rate or acidification may be occurring but this is insufficient to account for the deviant 137cs profiles in most of the lakes there is no evidence of mixing we argue that the occurrence of 137cs at prefallout sediment depths is due mostly to net downward molecular diffusion and adsorption and that surface concentration is due to net upward diffusion and adsorption and possibly also biological uptake recycling of sedimentary 137cs in the water column and delayed input from the watershed it is probable that much of the 137cs entering these lakes is carried by organic detritus mobility of 137cs in this sediment may be a function of release by organic decomposition and scarcity of clay minerals for adsorption correlation analyses of the sedimentary radionuclide activities vs physical and chemical characteristics of the lake water sediment and watersheds suggest that considerable trapping of 137cs and 210pb by terrestrial vegetation and organic soils is occurring the resultant delayed export to these lakes is contributing to the failure of 137cs as a dating tool but 210pb dating can be valid under these circumstances

water rock interaction and methanogenesis in formation water in the southeast huaibei coalfield china abstract the hydrogeochemical characteristics of aquifers in coal bearing strata can provide an important foundation for understanding the evolution of the aquifers and recognizing the formation process and occurrence of biogenic gas by analyzing the hydrogeochemical characteristics of water produced from the cenozoic the limestone and the coal strata aquifers and the coalbed gas wells this study focused on water rock interactions and methanogenesis in the formation water of the suzhou mining area huaibei coalfield china tectonically this is one of the most complex coalfields in china the dissolution of evaporites silicates and carbonates controlled the chemical composition of the formation water the cenozoic aquifers have a relatively stable water quality type and balanced ionic composition but more complex water rock interactions occur in the coal strata and the limestone aquifers extensive methanogenic activity and methanogenesis could be recognized by the meteoric water recharge positive 13 c signatures for dissolved inorganic carbon dic 15 4 26 2 lower sulfate concentrations

channel movement and erosion response to rainfall variability in southeast australia intrinsic and extrinsic forces on the catchment and stream channel network drive morphological change separating individual forcings is difficult given the complexity of such nonlinear systems here a modelling approach is used to investigate the sensitivity of channel position and movement under a series of realistic rainfall scenarios for a catchment in southeastern australia the results demonstrate the sensitivity of the catchment to different rainfall patterns and how relatively small changes in rainfall can lead to much larger sediment outputs revealing sensitivity to subtle changes in climate channel movement occurs as an avulsion this is the first time such a process has been observed and modelled in an ephemeral stream environment and demonstrates fluvial geomorphic change at human time scales human intervention by rock lining channels was demonstrated to prevent the movement of the main channel overall the caesar landscape evolution and erosion model used in this study is able to replicate both erosion rates and the variation in past channel movement the modelling suggests that any landscape change is based on both internal and external forcing and that landscape history also plays a significant role here we demonstrate the potential to quantify many of the nonlinearities and thresholds in soil mantled catchments using a landscape evolution model copyright 2011 john wiley sons ltd

climate and ephemeral stream processes twentieth century geomorphology and alluvial stratigraphy of the little colorado river arizona during the first 40 years of the twentieth century erosion was the dominant geomorphic process affecting the morphology of the little colorado river channel the discharge regimen was one of frequent large floods and high annual discharge that created a wide sandy channel free of vegetation in the 1940s and early 1950s average annual precipitation declined reducing annual discharge to about 57 of that of the preceding period as well as reducing the frequency of large floods the channel adjusted to the new hydrologic regimen by reducing its width parts of the channel were frequently dry and riparian vegetation primarily nonnative salt cedar became established on the higher channel surfaces precipitation and discharge thereafter increased and aggradation by overbank deposition was the primary geomorphic process as indicated by accretion of 2 to 5 m of flood plain alluvium between 1952 and 1978 events of 1980 however suggest that the flood plain has ceased to accrete although climate has not fluctuated the flood plain has probably reached a critical height above the channel beyond which further accretion is unlikely under the existing discharge regimen the recent history of the little colorado broadly suggests that flood plain development was initiated by climatically induced hydrologic fluctuations flood plain deposits in the stratigraphic column of such ephemeral streams may record repeated adjustments to altered hydrologic conditions

br cl na systematics in illinois basin fluids constraints on fluid origin and evolution the authors present here bromide chloride and sodium data for fluids from reservoirs of ordovician through pennsylvania age in the illinois basic which suggest that remnant marine fluids contribute significantly to fluid cl budgets cl br and nabr ratios for ordovician through devonian formation fluids are relatively uniform and near those for seawater despite greater than a factor of ten range in cl concentration in contrast fluids from mississippian and pennsylvanian reservoirs separated from older reservoirs by the new albany shale group have more variable fluid cl br and na br ratios most of which are significantly greater then those of seawater the 1 1 stoichiometry of cl and na increases for mississippian and pennsylvanian formation fluids is consistent with halite dissolution nevertheless br systematics and mass balance considerations indicate that he overall cl budget of illinois basin formation fluids appears to be more significantly influenced by the contribution from subaerially evaporated seawater than by halite dissolution

floodplain sedimentation rates in an alpine watershed determined by radionuclide techniques vertical profiles of the activities of 137cs and 210pb were measured on floodplain sediment cores and upland soil cores along the soda butte creek and the yellowstone river to determine floodplain sedimentation rates the position of mine tailings from a 1950 impoundment failure was used as a stratigraphic marker to estimate the sedimentation rates and to make comparisons with rates provided by radionuclide based methods mass accumulation sedimentation rates calculated from the position of the mine tailings ranged from 0 00 to 0 17 g cm 2 yr 1 and were in good agreement with sedimentation rates calculated from the inventories of 137cs and 210pb sedimentation rates calculated from the position of the 137cs peak generally overestimated the sedimentation rates probably because of increased downward migration of 137cs caused by the low ph of water moving through the mine tailings or the high permeability of floodplain sediments relative to upland reference soils this study demonstrates that the 137cs and 210pb inventory methods for determining sedimentation rates can be applied to an alpine floodplain where sedimentation events are episodic and where orographic effects on precipitation generate strong downstream gradients in the delivery of atmospheric radionuclides copyright 2007 john wiley sons ltd

introduction to unconventional petroleum systems ben law is a consultant and sole proprietor of pangea hydrocarbon exploration llc his research interests include basin centered gas and coalbed methane systems prior to his consulting position he was a member and chief of the u s geological survey western tight gas sand project and regional coordinator of south asia for the u s geological survey world energy project he received b s and m s degrees from san diego state university california john b curtis is associate professor and director petroleum exploration and production center potential gas agency at the colorado school of mines he is an associate editor for the aapg bulletin and the mountain geologist as director of the potential gas agency he works with a team of 145 geologists geophysicists and petroleum engineers in their biennial assessment of remaining united states natural gas resources the collection of articles included in this theme issue of the aapg bulletin originated in the aapg

coupling between 210pbex and organic matter in sediments of a nutrient enriched lake an example from lake chenghai china abstract sediment cores were collected from deep water areas of lake chenghai china in june 1997 the vertical profile of 137cs activity gives reliable geochronological results the results also indicate that sediment accumulation rates in deep water areas of lake chenghai were relatively constant in recent decades averaging 0 43 g cm 2 y 1 despite a variable organic carbon influx 210pbeq 226ra activity was relatively constant also with an average value of 54 3 3 2 bq kg 1 vertical profiles of 210pbex 210pbtotal 226ra decreased exponentially resulting in somewhat lower sediment accumulation rates 0 3 g cm 2 y 1 these lower rates are likely less reliable as the relatively large fluctuations in 210pbex activities correlate closely to the organic carbon corg content of the sediments for example the vertical profile of 210pbex activity displays peaks at mass depths of 3 7 4 7 g cm 2 10 12 cm and 10 11 g cm 2 25 28 cm similar to the maxima in the vertical profile of corg this phenomenon must be related to the delivery of particulate organic matter pom from the water to the sediments or to watershed soil erosion since the mean atomic ratios of horg corg and corg norg in lake chenghai sediments are 5 5 and 7 0 respectively indicating that pom was predominantly derived from the remains of authigenic algae this eliminates watershed erosion rates as a primary control on lake sedimentation rates as resolved by 210pbex sedimentation fluxes f corg of particulate organic carbon since 1970 varied between 60 to 160 g m 2 y 1 and appeared to closely influence variations in 210pbex concentrations for example sedimentation fluxes of 210pbex f 210pbex showed maxima in the years 1972 1974 and 1986 1989 likely reflecting historical variations of lake biological productivity or carbon preservation

use of radiometric cs 137 pb 210 geomorphic and stratigraphic techniques to date recent oxbow sediments in the rio puerco drainage grants uranium region new mexico in the absence of historic geochemical baseline data for the grants uranium region environmental changes resulting from uranium mine mill activities can be determined only by indirect methods a methodology for determining the age of recent sediments in streams draining the region has been established based on combined geomorphic stratigraphic and radiometric dating techniques because clayrich sediments retain possible radionuclides and heavy metals derived from mineralization and mined sources sample sites which contain fine grained deposits that both predate and postdate mine mill activity were located in abandoned channel segments oxbows of major streams draining the eastern grants uranium region aerial photographs and derivative maps taken between 1935 and 1971 provided the historical and geomorphic documentation of approximate dates of oxbow formation and ages of alluvial fills in the abandoned channel segments pits were dug at these oxbow sites to determine stratigraphy and composition of the deposits samples collected from pit walls and auger holes below the pits were subjected to radiometric analysis by gamma ray spectrometry for the artificial radionuclide cs 137 and the natural radionuclide pb 210 as well as other u 238 and th 232 daughters because of the dynamic nature of the system absolute dating with cs 137 was not possible but samples could be dated as either pre or post 1950 the 1950 date is important because it marked the beginning of the uranium exploitation in the region the pb 210 dating was not possible because background pb 210 was very high relative to fallout pb 210

accuracy of post bomb 137cs and 14c in dating fluvial deposits abstract the accuracy and precision of 137cs and 14c for dating post 1950 alluvial deposits were evaluated for deposits from known floods on two rivers in arizona the presence of 137cs reliably indicates that deposition occurred after intensive above ground nuclear testing was initiated around 1950 there was a positive correlation between the measured level of 137cs activity and the clay content of the sediments although 137cs was detected even in sandy flood sediments with low clay content 137cs is a valuable dating tool in arid environments where organic materials for 14c or tree ring dating are scarce and observational records are limited the 14c activity measured in different types of fine organic detritus yielded dates within 1 to 8 yr of a 1980 flood deposit and the accuracy was species dependent however undifferentiated mixtures of fine organic materials from several post bomb deposits of various ages repeatedly yielded dates between 1958 and 1962 and detrital charcoal yielded a date range of 1676 1939 in semiarid environments the residence time of most types of organic debris precludes accurate annual resolution of post bomb 14c dates

a 1600 year diatom record of hydroclimate variability from wolf lake new york a high resolution diatom record from wolf lake a minimally disturbed heritage lake provides insights into the hydroclimatic history of the adirondack mountains of northern new york during the last c 1600 years three pronounced dry periods occurred during c ad 490 610 780 870 and 1010 1080 and low precipitation generally prevailed during the warm medieval climate anomaly c ad 950 1350 a finding that fills an important gap in knowledge of the spatial extent of droughts across north america during that period during the cooler little ice age interval c ad 1350 1800 inferred water balance was generally more positive seven peaks in charcoal abundance represent fire events during both wet and dry periods unusually high charcoal and inorganic sediment deposition c ad 1700 could reflect human activity in the watershed as might an abrupt rise in the relative abundances of planktonic and tychoplanktonic diatoms in wolf lake during the ad 1860s the diatom record displays periodicities of c

longitudinal variability of the mesopause sao a longitudinal variation in the mesopause semi annual oscillation sao is documented from wind observations made by the high resolution doppler imager satellite instrument the asymmetry is dominated by a wavenumber 1 pattern with a variable phase during the easterly phase of the mesopause sao equinoxes maximum tropical easterlies occur over eastern south america and the atlantic ocean in the longitude band 300 360 during the westerly phase solstices the westerly winds descend more rapidly and are larger below 80 km in this same atlantic longitude band to the best that can be determined with sparse data the longitudinal asymmetries near the stratopause are weak and are in phase with those in the mesosphere

genetic and temporal relations between formation waters and biogenic methane upper devonian antrim shale michigan basin usa abstract controversy remains regarding how well geochemical criteria can distinguish microbial from thermogenic methane natural gas in most conventional deposits has migrated from a source rock to a reservoir rarely remaining associated with the original or cogenetic formation waters we investigated an unusual gas reservoir the late devonian antrim shale in which large volumes of variably saline water are coproduced with gas the antrim shale is organic rich of relatively low thermal maturity extensively fractured and is both source and reservoir for methane that is generated dominantly by microbial activity this hydrogeologic setting permits integration of chemical and isotopic compositions of coproduced water and gas providing a unique opportunity to characterize methane generating mechanisms the well developed fracture network provides a conduit for gas and water mass transport within the antrim shale and allows invasion of meteoric water from overlying aquifers in the glacial drift steep regional concentration gradients in chemical and isotopic data are observed for formation waters and gases dilute waters grade into dense brines 300 000 ppm over lateral distances of less than 30 km radiogenic 14c and 3h and stable isotope 18o and d analyses of shallow antrim shale formation waters and glacial drift groundwaters indicate recharge times from modern to 20 000 yr bp carbon isotope compositions of methane from antrim shale wells are typical of the established range for thermogenic or mixed gas 13c 47 to 56 however the unusually high 13c values of co2 coproduced with methane 22 and dissolved inorganic carbon dic in formation waters 28 require bacterial mediation the d values of methane and coproduced formation water provide the strongest evidence of bacterial methanogenesis methane ethane propane ratios and 13c values for ethane indicate 1 the presence of a thermogenic gas component that increases basinward and 2 progressive bacterial oxidation of ethane as the antrim shale subcrop is approached multiple episodes of pleistocene glaciation over northern michigan appear critical to the development of these gas deposits loading of thick ice sheets may have provided hydraulic head that enhanced dilation of preexisting fractures and influx of meteoric water the physical erosion cycle of repeated glacial advances and retreats exhumed the antrim shale around the northern margin of the michigan basin subjecting it to near surface physiochemical and biochemical processes the chemical and hydrologic relations demonstrated in the antrim shale reservoir suggest a dynamic connection between pleistocene glacial history of the midcontinent region and development of recoverable microbially generated natural gas reserves

thermogenic and secondary biogenic gases san juan basin colorado and new mexico implications for coalbed gas producibility the san juan basin is the most prolific coalbed gas basin in the world with 1992 production exceeding 440 gcf footnote 12 4 billion m3 resources of approximately 50 tcf 1 4 trillion m3 and proved reserves of over 6 tcf 170 billion m3 coalbed gas wells with the highest production initial potential greater than 10 mcf day or 0 28 million m3 day occur in the overpressured north central part of the basin hydrologic analysis indicates that overpressure in the fruitland formation is artesian in origin and represents repressuring that developed during the middle pliocene highly permeable laterally continuous coal beds override abandoned shoreline pictured cliffs sandstones and extend to the elevated recharge area in he northern basin to form a dynamic regionally interconnected aquifer system coal rank and basin hydrodynamics control the composition of fruitland coalbed gases which varies significantly across the basin chemically dry gases in the north central part of the basin coincide with meteoric recharge and regional overpressure the consistency of methane dgr13c values across the basin the presence of isotopically heavy carbon dioxide in coalbed gases and bicarbonate in formation waters and biodegraded n alkane distributions of some coal extracts indicate that coalbed gases in the north central basin are a mixture of thermogenic 25 50 secondary biogenic 15 30 and migrated thermogenic 12 60 gases migrated conventionally and hydrodynamically trapped gases in situ generated secondary biogenic gases and solution gases result in gas content that plot on or above the coal sorption isotherm bacteria transported basinward in groundwater flowing from the elevated northern basin margins metabolized wet gas components n alkanes and organic compounds in the coal and generated secondary biogenic methane and carbon dioxide subsequent to coalification uplift erosion and cooling these gases may be limited to basin margins where shallow depths and structural deformation result in higher permeability or may extend more than 35 mi 56 km basinward from the recharge zone the presence of appreciable secondary biogenic gas indicates an active dynamic flow system with overall permeability sufficient for high productivity basin hydrogeology reservoir heterogeneity location of permeability barriers no flow boundaries and the timing of biogenic gas generation and trap devel pment are critical for exploration and development of unconventional gas resources in organic rich rocks

relative sea level response to little ice age ice mass change in south central alaska reconciling model predictions and geological evidence abstract integration of geological data and glacio isostatic adjustment gia modelling shows that it is possible to decouple complex mechanisms of relative sea level rsl change in a tectonically active glacial environment we model a simplest solution in which rsl changes in upper cook inlet alaska are a combination of the interplay of tectonic and isostatic processes driven by the unique rheology of this tectonically active location we calculate interseismic uplift during latter part of the penultimate earthquake cycle to vary from 0 3 to 0 7 mm yr diatom based reconstructions of rsl from tidal marsh sediment sequences coupled with detailed age models from ad 1400 to the ad 1964 great earthquake show deviations from a purely tectonically driven model of regional rsl glacial isostatic modelling constrained by gps data predicts up to 70 cm sea level change due to mountain glacier mass balance changes during the little ice age misfits between the gia model predictions and rsl reconstructions in the 19th and 20th century highlight that the tidal marshes of upper cook inlet potentially record a hemispheric wide acceleration in sea level and that other more complex earth process combinations may contribute to regional rsl change

massive mn carbonate formation in the landsort deep baltic sea hydrographic conditions temporal succession and mn budget calculations abstract the sediments of the landsort deep and gotland basin in the central baltic sea are strongly enriched in mn carbonate however conceptual models attempting to explain the intense mn carbonate precipitation in both basins are in part conflicting in the gotland basin model deposited mn oxides are converted to mn carbonate after the oxygenation of euxinic bottom waters enriched in dissolved mn by major baltic inflows huckriede and meischner 1996 by contrast according to the landsort deep model mn carbonate precipitation occurs independent of oxygenation events below a euxinic water column lepland and stevens 1998 lenz et al 2015 in this study we investigated mn solid phase signatures in recent sub recent well dated sediments from the landsort deep and compared them to long term observations to identify the hydrographic conditions favoring mn carbonate formation the comparisons of water column o2 and sulfide time series with sedimentary mn carbonate enrichments identified long lasting bottom water oxygenation as an important environmental factor in the enhancement of mn carbonate precipitation up to 32 wt mn in the landsort deep thus by preventing the escape of dissolved mn from still reducing sediments into the open water column these conditions allow the accumulation of large amounts of mn oxide particles at the sediment water interface with their subsequent conversion to mn carbonate the euxinic conditions that have prevailed almost continuously in the landsort deep since roughly ad 2000 do not favor mn enrichment maximum 0 9 wt mn highlighting the importance of the recurring oxygenation of bottom water most likely via medium intensity inflows the mn abundances in seven sediment cores from water depths of 190 437 m together with mn balance calculations indicated that the mn inventory in the water column in response to porewater mn reflux and detrital mn input is sufficient for mn carbonate enrichment only in the deepest part of the basin

climatology of the stationary planetary waves seen in the saber timed temperatures 2002 2007 1 the paper focuses on the global spatial structure seasonal and interannual variability of the stationary planetary waves spw with zonal wavenumber s 1 spw1 and s 2 spw2 derived from the saber timed temperature measurements for 6 full years january 2002 december 2007 the monthly mean climatological multiyear average 2002 2007 depictions of spw temperature field extending between 20 and 120 km altitude and 50 latitude are derived a special attention is paid to the spw temperature field in the lower thermosphere where the spw1 amplifies in may and december january in the northern hemisphere nh and in april may and november in the southern hemisphere sh amplitudes in both hemispheres are similar in strato mesosphere however in the lower thermosphere sh amplitudes are significantly larger 30 k than those in nh 20 k the nh spw1 is able to propagate up to 115 km altitude contributing to the winter amplification of the lower thermospheric spw1 but that from the sh cannot penetrate above 90 100 km in the lower thermosphere above h 100 km mainly trapped spw signal is observed the spw1 are almost out of phase in both hemispheres the average 2002 2007 phases are 100 w in nh and 120 e in sh strong evidence indicates that auroral heating is a main origin of the lower thermospheric spw temperature field

210pb and 137cs chronology of sediments from small shallow arctic lakes abstract arctic environmental conditions present special difficulties with the use of nuclides 210pb and 137cs for measuring lake sediment chronology fluxes of these nuclides are lower in the arctic than in mid latitudes shortening the history that can be resolved ice prevents atmospheric input of nuclides to sediment during much of the year and can cause redistribution of sediment in shallow lakes results from analyses of seven sediment cores from two lakes on the belcher islands in southeastern hudson bay show that sediment redistribution by ice is a major process in one of the lakes in order to measure an undisturbed sedimentation rate it is necessary that a total input or flux of 137cs and 210pb be measured or estimated total unsupported 210pb in the area 14 8 dpm cm2 is the average of measurements in three cores from two lakes that have consistent total 137cs inventories closest to the estimated 137cs flux cores from undisturbed sites have slower sedimentation rates and 137cs appears in layers dated before the early 1950s when it would have first appeared in sediment 137cs cannot be used for chronological evaluation of these cores mixing of surface sediment layers and lower dating resolution than in other cores are responsible for the apparent downward movement of this nuclide 210pb measurements of undisturbed sedimentation rates in the lakes range from 0 0044 to 0 0180 g cm2 a the sedimentation rate in a lake used for raw sewage oxidation doubled after the beginning of sewage input rates at sites where sediment is redistributed range from 0 0259 to 0 0309 g cm2 a with similarly higher total 137cs and unsupported 210pb values dates of sediment layers measured using the constant rate of supply model are verified by 210pb profile discontinuities corresponding to major storms in 1958 and in 1940

natural 210pb 7be and fallout 137cs 239 240pu 90sr radionuclides as geochemical tracers of sedimentation in greifensee switzerland the average sedimentation rate of greifensee has been evaluated by using varve counting and 210pb and fallout radionuclide dating from 4 different sites in the lake to amount to 0 14 0 02 g cm 2 yr 1 the geochronology of greifensee agrees with previous dating attempts based on varve counting of sediments from the deepest part of the lake emerson and widmer 1978 a simple erosion model for substances derived predominantly from the drainage basin can explain the inventories of the natural and fallout radionuclides in the lake sediments

hydrogeochemistry and gas compositions of the uinta basin a regional scale overview the geochemistry of formation fluids water and hydrocarbon gases in the uinta basin utah is evaluated at the regional scale based on fluid sampling and compilation of past records the deep formation water is dominated by na cl type where halite dissolution has the greatest effects on water chemistry its distribution and composition is controlled by both the lithology of geological formations and regional hydrodynamics the origin of the saline waters in the southeastern basin is interpreted to be a mix of ancient evaporatively concentrated seawater with meteoric water recharged in the geological past which has experienced water rock interactions at the basin scale three dimensional mapping of the dissolved solid contents further reveals that 1 in the northern uinta basin bordering the uinta mountains significant flushing of the deep basinal brines up to 6 km 3 7 mi depth by meteoric water has occurred and 2 in the central basin groundwater discharge areas along the green river valley regional upwelling of saline waters from 2 to 3 km 1 2 to 1 8 mi depth is occurring moreover gas composition and water gas stable isotope characteristics in the central to southeastern basin indicate the presence of a deep thermogenic and regionally continuous gas deposit in particular gases sampled in this region from the wasatch formation and mesaverde group indicate a similar source rock type iii kerogen of the deeply buried thermally mature mesaverde group in the central to northern basin as well as migration from the natural buttes gas field toward the southeastern basin evidence for biogenic methane formation is observed only in the upper green river formation in the central to northern uinta basin here the organic rich immature green river shales experience meteoric water invasions and formation fluid chemistry and stable isotope compositions are diagnostic of microbial methanogenesis

distributions of polycyclic aromatic hydrocarbons in a sediment core from the north basin of lake biwa japan abstract we analyzed the vertical distributions of 19 polycyclic aromatic hydrocarbons pahs total organic carbon toc total nitrogen tn and stable carbon isotope ratio 13 c in a 27 cm sediment core from the north basin of lake biwa in order to elucidate changes in pah sources and events possibly affecting the lake over the last few decades both toc and tn increased gradually from the deepest layer toc 1 2 wt tn 0 14 wt to the uppermost layer toc 4 0 wt tn 0 45 wt the toc tn ratio a useful indicator for distinguishing between aquatic and terrestrial plant sources increased remarkably at 11 13 cm 10 3 11 1 vs 8 5 9 7 at other depths indicating that large amounts of terrestrial material entered the lake when that layer was deposited all pahs except perylene gradually increased from the deepest layer but not as clearly as toc and tn at 11 13 cm all pahs except perylene transiently decreased and perylene transiently increased since the pah ratios used for the elucidation of sources did not change greatly throughout the core we consider that the major source of pahs in the lake has not changed during the last few decades the brief decrease in pahs at 11 13 cm could be the result of dilution by a large input of terrestrial material which brought in perylene

a stationary planetary scale feature in the tropical mesopause temperature field three years of daily global temperature grids at 5 7 9 and 12 scale heights have been retrieved from nimbus 6 pressure modulator radiometer measurements a stationary pattern is observed in the tropical 12 scale height about 82 km altitude seasonal and monthly mean temperatures that has an approximately wavenumber four zonal structure this pattern has warm centers located near the equator and cold centers positioned some 10 to 20 degrees of latitude away towards the winter pole the amplitude of this pattern varies in a semiannual fashion with maxima occurring during late winter and late summer the structure and behavior of the feature compares well with the seasonal changes in tropical deep convective storms leading to speculation that the feature may be driven by tropospheric gravity waves

immobility of 210pb in black sea sediments we measured 210pb in a core from the deep black sea which contained a turbidite of low 210pb activity surrounded above and below by pelagic sediments of much higher activity to evaluate in situ210pb mobility under the anoxic moderately sulfidic conditions by measuring at millimeter scales across the distinct laminae turbidite contacts and modeling the observed profile we estimated a lower limit of the kd of 107 deff 5 10 13 this result increases confidence in sediment chronologies from the black sea based on 210pb because it implies that profiles will not be altered significantly by diffusive transport of 210pb below the turbidite the 210pb inferred accumulation rate was 50 g m2 a which is lower than laminae based estimates by a factor of 3 4

new insights on the green river petroleum system in the uinta basin from hydrous pyrolysis experiments the tertiary green river petroleum system in the uinta basin generated about 500 million bbl of recoverable high pour point paraffinic crude oil from lacustrine source rocks a prolific complex of marginal and open lacustrine source rocks dominated by carbonate oil shales containing up to 60 wt type i kerogen occur within distinct stratigraphic units in the basin petroleum generation is interpreted to originate from source pods in the basal green river formation buried to depths greater than 3000 m along the steeply dipping northern margin of the basin producing fields in the altamont bluebell trend have elevated pore fluid pressures approaching 80 of lithostatic pressure and are completed in strata where open fractures provide permeability active hydrocarbon generation is one explanation for the origin of the overpressured reservoirs in this study experiments were undertaken to examine the mechanisms of hydrocarbon generation and accumulation in the uinta basin we combined analyses of representative source rocks from the entire green river stratigraphic section with detailed laboratory simulation experiments using both open and closed system pyrolysis this information provides new insights on lacustrine source rock lithofacies gas oil source rock correlations hydrocarbon generation kinetics and basin modeling the results show that the basal green river formation contains a unique type i source facies responsible for generation of paraffinic crude oils the classic type i oil shales in the upper green river formation correlate well with low maturity aromatic asphaltic samples we determined kinetic parameters for the source rocks and used them to develop basin models for hydrocarbon generation the models show that hydrous pyrolysis kinetic parameters are more consistent with the natural data in terms of predicted timing and extent of oil generation as compared to models using rock eval kinetics begin page 1334

a time resolution methodology for assessing the quality of lake sediment cores that are dated by 137cs a methodology is proposed for grading the utility of lake sediment cores used to reconstruct pollution histories the observed distribution of sup 137 cs with depth in the core is compared to that expected from independent historic measurements of fallout deposition the width of the sup 137 cs peak is the core profile that corresponds to the fallout maximum of 1963 or the combined maxima of 1959 and 1963 is used to infer the inherent time resolution of the core i e the ability to distinguish events in the deposition history of the watershed the method is applied to a number of core profiles from various lakes in the us and appears to provide self consistent results

post deposition diffusion of 137cs in lake sediment implications for radiocaesium dating peak activities of radiocaesium 137cs in lake sediments have frequently been used to infer the ages of sediments deposited in the 1960s 137cs derived from nuclear bomb testing or in 1986 chernobyl derived 137cs records of the vertical distribution of 137cs in sediments can thus be used to provide accurate dates for a critical period in which palaeoecological reconstructions often overlap contemporary monitoring data however knowledge regarding how the distribution of 137cs in sediments is affected by post depositional processes is limited to interpretations based on the 137cs distribution in sediments sampled at a single given date this study assesses the extent to which the 137cs record in annually laminated varved lake sediments is affected by post depositional diffusion using 11 archived sediment cores sampled between 1986 and 2007 the sediment record reveals how chernobyl 137cs incorporated into the 1986 varve diffused downwards in the core at a decreasing rate over time whereas the surface sediments continued to receive inputs of 137cs mobilized from the catchment soils or lake margin in spite of these processes all cores post dating the chernobyl accident had a clear and well resolved peak in the 1986 varve justifying the use of this feature as a fixed chronostratigraphic feature because of the very high levels of chernobyl fallout at this site downwards migration of chernobyl 137cs has however completely masked the nuclear weapons 137cs fallout peak that had been clearly preserved in the 1964 varve of a pre chernobyl core sampled just three weeks before the chernobyl accident in consequence the weapons fallout marker is likely to be of little use for determining 137cs dates in areas strongly affected by high levels of chernobyl fallout

atmospheric deposition of cadmium in the northeastern usa abstract lake sediment cores dated by 210pb were collected from spectacle pond sp massachusetts and side pistol lake spl and sargent mountain pond smp maine usa sp is a kettle seepage lake in granitic sand and gravel smp is a drainage pond on granite with little soil in the small watershed spl is a drainage lake in granitic till the three cores were analyzed for total cd for sp and smp maximum concentrations of 1 7 and 3 9 mg kg four and eight times background concentrations respectively occur in the late 1960s accumulation rates reach maximum values concurrently with concentration and are 0 054 and 0 016 g cm2 a more than 10 times background concentration and accumulation rate age relationships in smp and sp are similar for background values timing and magnitude of increase to peak values and the decrease nearly to background values since about 1975 the chemical response to decreased atmospheric deposition lags in spl sediment kettle like lakes more clearly indicate changes in atmospheric deposition than drainage lakes

fayetteville green lake new york u s a viii mass balance for 137cs in water varved and non varved sediments abstract a mass balance for 137 cs was done in fayetteville green lake 43 of total 137 cs input was found in shallow water 0 18 m sediments 16 was found in deep water varved sediments 9 was found in the water column and 32 remained to be carried away by lake outflow shallow water sedimentary 137 cs must be resuspended and or dissolved to maintain current levels of 137 cs in the water column and current fluxes of 137 cs to deep water varved sediments 137 cs activities in individual varve year samples from 1946 to 1976 followed closely the pattern of published bomb fallout records but the varves contained only 28 34 of cumulative unit area fallout for this area in order to preserve the yearly record of 137 cs sedimentation the pore water diffusion coefficient for 137 cs must be 11 cm 2 s 1 bioturbation and physical mixing of these sediments does not occur some of the cores of shallow water sediments accumulated 137 cs in amounts greater than was supplied by fallout to the lake surface area this may be due to 1 horizontal transport of surface water 137 cs to shallow water sediments for direct absorption 2 bioconcentration by benthic algae and mosses or 3 localized funnelling of sediments

the influence of radon diffusion on the 210pb distribution in sediments a mathematical model is presented which describes the distribution of radon 222 in sediments having a constant or variable depth distribution of radium 226 the model is extended to the distribution of lead 210 taking into account the mobility of radon the precursor of 210pb within the sediment column the 210pb model is compared at constant radium activity with the conventional approach which disregards the radon diffusion when estimating sedimentation rates by the 210pb method the ratio between apparent and real sedimentation rate s s expressed as a function of three dimensionless parameters demonstrates the importance of the radon diffusion effect this effect is particularly important for sediments with small initial excess 210pb activity small sedimentation rate large radon diffusivity or a combination of these factors applied to lake geneva the sedimentation is estimated to be larger by 30 50 than the original value by krishnaswami et al 1971 in sediments which are mixed at the surface physical mixing or bioturbation the 210pb activity in the mixed layer is diminished compared to that in the settling sediment material robbins et al 1977 and radon diffusion makes the activity difference even larger especially for low initial excess 210pb activity small sedimentation rate and large mixing intensity this result may be of importance for the balance of 210pb in an aquatic system if the calculations are based on activities measured in the sediment

the origin of stationary planetary waves in the upper mesosphere abstract satellite observations indicate that quasi stationary planetary waves often exist to at least 100 km in the winter mesosphere waves are also seen in the summer upper mesosphere a three dimensional numerical model was used to simulate these waves and to diagnose the physical processes involved the waves simulated in the model closely resemble observed waves several model runs that isolate specific processes are used to determine the relative importance of two forcing mechanisms in the model planetary waves that propagate from below are significantly damped at the altitude where gravity wave drag becomes large about 75 km in the winter midlatitudes or below if a reversal in the mean wind is encountered momentum forcing associated with breaking gravity waves that have been filtered by planetary scale wind variations below acts to generate planetary waves in the middle and upper mesosphere the amplitude from in situ forcing by gravity wave breaking exceeds the amplitude from the upward prop

microbial production and modification of gases in sedimentary basins a geochemical case study from a devonian shale gas play michigan basin an expanded data set for gases produced from the antrim shale a devonian black shale in the michigan basin united states has allowed for a detailed examination of the related chemical and isotopic compositional changes in the solid gas liquid systems that discriminate between microbial and thermogenic gas origin in the antrim shale economic microbial gas deposits are located near the basin margins where the shale has a relatively low thermal maturity and fresh water infiltrates the permeable fracture network the most compelling evidence for microbial generation is the correlation between deuterium in methane and coproduced water along the basin margins there is also a systematic enrichment in 13c of ethane and propane with decreasing concentrations that suggests microbial oxidation of these thermogenic gas components microbial oxidation accounts not only for the shift in 13c values for ethane but also in part for the geographic trend in gas composition as ethane and higher chain hydrocarbons are preferentially removed this oxidation is likely an anaerobic process involving a syntrophic relationship between methanogens and sulfate reducing bacteria the results of this study are integrated into a predictive model for microbial gas exploration based on key geochemical indicators that are present in both gas and coproduced water one unequivocal signature of microbial methanogenesis is the extremely positive carbon isotope values for both the dissolved inorganic carbon in the water and the coproduced co2 gas in contrast the 13c value of methane is of limited use in these reservoirs as the values typically fall between the commonly accepted fields for thermogenic and microbial gas in addition the confounding isotopic and compositional overprint of microbial oxidation increasing the values to typically thermogenic values may obscure the distinction between methanogenic and thermogenic gas

relation of natural gas composition to thermal maturity and source rock type in san juan basin northwestern new mexico and southwestern colorado san juan basin is a roughly circular asymmetric structural depression located in northwestern new mexico and southwestern colorado ultimate recoverable reserves of predominantly nonassociated gas 23 tcf 0 65 1012 m3 are present in the structurally low part of the central basin the major producing intervals are low permeability sandstone reservoirs in the upper cretaceous dakota sandstone mesaverde group and pictured cliffs sandstone lesser amounts of oil and or gas are produced from pennsylvanian jurassic and cretaceous rocks along the southern and western flanks of the basin the gases display a trend of becoming isotopically heavier dgr13c1 values range from 48 7 to 31 4 pmil and chemically drier c1 c1 5 values range from 0 75 to 0 99 with increasing depth these changes are assumed to be the result of thermal cracking processes and the gases are interpreted to have been generated during the mature and post mature stages of hydrocarbon generation however there is considerable scatter in the data which is interpreted to result from a difference in source rock type gases generated from nonmarine humic source rocks are isotopically heavier and chemically drier than those generated from marine sapropelic source rocks at equivalent levels of maturity the gases also become isotopically heavier and chemically drier to the northeast following the trend of increasing maturity of all units in that direction the increase in maturity is attributed to a combination of greater burial depth and a higher geothermal gradient resulting from batholiths to the north in the san juan mountains area maximum burial and heat flow occurred during the oligocene which probably coincided with peak hydrocarbon generation lack of oil in the central basin is believed to be the result of two factors first gas in reservoirs such as the dakota sandstone may have resulted from thermal cracking of oil generated from marine source rocks during late mature wet gas condensate and post mature dry gas stages of hydrocarbon generation second gas in reservoirs such as mesaverde group and pictured cliffs sandstone is nonassociated and probably was generated from nonmarine coaly organic matter during the mature and post mature stages minor amounts of condensate instead of oil may have been generated from nonmarine source rocks during the mature stage

accumulation rates and sediment deposition in the northwestern mediterranean abstract as part of the eros 2000 programme sediment mixing and accumulation rates in the northwestern mediterranean sea were determined applying the 210 pb dating method to a total of 49 cores and the results from 29 sediment cores are presented here on the basis of the results from the 49 sediment cores an attempt was made to present a general picture of sediment accumulation for the area of the northwestern mediterranean the total deposition of sediment in the area is estimated to be of the order of 34 15 10 6 ton year 1 which is half the value reported earlier by got and aloisi 1990 continental shelf research 10 841 855 for the same region the activity depth profiles of 210 pb show the presence of intensive mixing in the upper layer of near shore sediments but little or no mixing is observed in the deep water sediments based on a diffusion model sediment mixing rates calculated from excess 210 pb gradients vary from 0 002 to 7 cm 2 year 1 and the deposition rates from 0 01 to 0 60 cm year 1 a linear dependence of sedimentation rate on water depth derived from the sediment cores indicates an inverse correlation between these two the relatively high sedimentation rates and mixing rates found near the rho ne river suggest that the contribution from the river dominates the deposition system in the northwestern mediterranean in the deep water basin however atmospheric input and biological production are clearly more important

beryllium 7 and lead 210 chronometry of modern soil processes the linked radionuclide accumulation model lrc abstract soil systems are known to be repositories for atmospheric carbon and metal contaminants but the complex processes that regulate the introduction migration and fate of atmospheric elements in soils are poorly understood this gap in knowledge is attributable in part to the lack of an established chronometer that is required for quantifying rates of relevant processes here we develop and test a framework for adapting atmospheric lead 210 chronometry 210 pb half life 22 years to soil systems we propose a new empirical model the linked radionuclide accumulation model lrc aka lark that incorporates measurements of beryllium 7 7 be half life 54 days to account for 210 pb penetration of the soil surface during initial deposition a process which is endemic to soils but omitted from conventional 210 pb models e g the constant rate of supply crs model and their application to sedimentary systems we validate the lrc model using the 1963 1964 peak in bomb fallout americium 241 241 am half life of 432 years as an independent corroborating time marker in three different soils we locate a sharp 241 am weapons horizon at disparate depths ranging from 2 5 to 6 cm but with concordant ages averaging 1967 4 via the lrc model similarly at one site contaminated with mercury hg t we find that the lrc model is consistent with the recorded history of hg emission the close agreement of pb am and hg behavior demonstrated here suggests that organo metallic colloid formation and migration incorporates many trace metals in universal soil processes and that these processes may be described quantitatively using atmospheric 210 pb chronometry the 210 pb models evaluated here show that migration rates of soil colloids on the order of 1 mm yr 1 are typical but also that these rates vary systematically with depth and are attributable to horizon specific processes of leaf litter decay eluviation and illuviation we thus interpret 210 pb models to quantify i exposure of the soil system to atmospheric aerosol deposition in the context of ii organic carbon assimilation colloid production and advection through the soil profile the behavior of some other elements such as cs diverges from the conservative colloid behavior exemplified by pb and am and in these cases the value of empirical 210 pb chronometry models like lrc and crs is as a comparator rather than as an absolute chronometer we conclude that 210 pb chronometry is valuable for tracing colloidally mediated transport of pb and similarly refractory metals as well as the mobile pool of carbon in soils

developmental geology of coalbed methane from shallow to deep in rocky mountain basins and in cook inlet matanuska basin alaska u s a and canada abstract the rocky mountain basins of western north america contain vast deposits of coal of cretaceous through early tertiary age coalbed methane is produced in rocky mountain basins at depths ranging from 45 m 150 ft to 1 981 m 6 500 ft from coal of lignite to low volatile bituminous rank although some production has been established in almost all rocky mountain basins commercial production occurs in only a few despite more than two decades of exploration for coalbed methane in the rocky mountain region it is still difficult to predict production characteristics of coalbed methane wells prior to drilling commonly cited problems include low permeabilities high water production and coals that are significantly undersaturated with respect to methane sources of coalbed gases can be early biogenic formed during the early stages of coalification thermogenic formed during the main stages of coalification or late stage biogenic formed as a result of the reintroduction of methane generating bacteria by groundwater after uplift and erosion examples of all three types of coalbed gases and combinations of more than one type can be found in the rocky mountain region coals in the rocky mountain region achieved their present ranks largely as a result of burial beneath sediments that accumulated during the laramide orogeny late cretaceous through the end of the eocene or shortly after thermal events since the end of the orogeny have also locally elevated coal ranks coal beds in the upper part of high volatile a bituminous rank or greater commonly occur within much more extensive basin centered gas deposits which cover large areas of the deeper parts of most rocky mountain basins within these basin centered deposits all lithologies including coals sandstones and shales are gas saturated and very little water is produced the interbedded coals and carbonaceous shales are probably the source of much of this gas basin centered gas deposits become overpressured from hydrocarbon generation as they form and this overpressuring is probably responsible for driving out most of the water sandstone permeabilities are low in part because of diagenesis caused by highly reactive water given off during the early stages of coalification coals within these basin centered deposits commonly have high gas contents and produce little water but they generally occur at depths greater than 5 000 ft and have low permeabilities significant uplift and removal of overburden has occurred throughout the rocky mountain region since the end of the eocene and much of this erosion occurred after regional uplift began about 10 ma the removal of overburden generally causes methane saturation levels in coals to decrease and thus a significant drop in pressure is required to initiate methane production the most successful coalbed methane production in the rocky mountain region occurs in areas where gas contents were increased by post eocene thermal events and or the generation of late stage biogenic gas methane generating bacteria were apparently reintroduced into the coals in some areas after uplift and erosion and subsequent changes in pressure and temperature allowed surface waters to rewater the coals groundwater may also help open up cleat systems making coals more permeable to methane if water production is excessive however the economics of producing methane are impacted by the cost of water disposal

sedimentological controls on the fracture distribution and network development in mesaverde group sandstone lithofacies uinta basin utah usa the mesaverde group uinta basin utah is the source of current significant natural gas production and contains several trillion cubic feet of undiscovered natural gas resources to evaluate and model the potential connectivity of hydraulically induced fractures to natural fractures in the subsurface the natural fracture network was examined using scanline sampling image and well logs core and microstructural analyses regional fracture sets include subvertical fractures with dominant orientations of north south 006 0158 ne 045 0598 nnw 326 3428 and a wnw 271 2868 sedimentologic and diagenetic characteristics of seven sandstone lithofacies control the fracture development and distribution in the group key sedimentologic and diagenetic influences on fracture distribution include bed thickness stratigraphic architecture the degree of cementation and the type of cement from these sedimentologic controls on the character of natural fractures lithofacies can potentially predict fracture distribution within the mesaverde group based on environments of deposition the presence of nw trending discontinuous sandstone reservoirs deposited in meandering fluvial environments that are highly fractured by a pervasive wnw striking fracture set helps to explain fairways of prolific natural gas production within

constraints on the origins of hydrocarbon gas from compositions of gases at their site of origin it is widely accepted that natural gas is formed from thermal decomposition of both oil in reservoirs and to a lesser extent the organic matter in shales from which the oil was derived1 6 but laboratory pyrolysis experiments on shales do not reproduce the methane rich composition typical of most gas reservoirs7 leading to suggestions7 that other mechanisms such as transition metal catalysis may be important the discrepancy might however instead arise because gas and oil deposits have migrated from their source rocks so that the reservoir composition might not be representative of the composition in the source rocks where the hydrocarbons were generated to address this question we have analysed gas samples coproduced with oils directly from a source rock the bakken shales north dakota usa where the local geology has prevented significant hydrocarbon migration the methane contents of these bakken shale gases are much lower than that of conventional gas reservoirs but are consistent with that from pyrolysis experiments8 9 on these shales thus because these bakken gases form with rather than from oils we argue that compositional differences between gases from source rocks and conventional gas deposits result from fractionation processes occurring after hydrocarbon expulsion from the source rock

the waikari river tsunami new zealand s largest historical tsunami event abstract the waikari river tsunami was caused by a landslide triggered by the 1931 hawke s bay earthquake new zealand s deadliest natural disaster to date although it was reported in newspapers and personal diaries at the time this is the first study to examine the tsunami using a multi proxy approach aimed at investigating the physical evidence of this event sedimentological geochemical chronological and microfossil analyses were carried out on an anomalous gravel layer within the sedimentary sequence of waikari station located in a meander bend close to the river mouth the chronology was established by extrapolation from 137cs data coupled with historical artefacts found within the gravel layer diatoms within the deposit were brackish and most probably sourced from the adjacent tidally influenced waikari river principal component analysis performed on geochemical data showed that the anomalous gravel layer at all sites is associated with a cluster of elements not related to detrital input nor organic matter but indicative of an estuarine source a second older gravel layer was also identified it is considered to have been deposited by an earlier tsunami quite likely caused by a landslide generated by the 1863 hawke s bay earthquake the deposit has similar sedimentological geochemical and microfossil characteristics to the gravel layer deposited by the 1931 event this study adds valuable insights into the poorly understood topic of landslide generated tsunamis by investigating the largest historical event of its kind to occur in new zealand

production waters associated with the ferron coalbed methane fields central utah chemical and isotopic composition and volumes this study investigated the composition of water co produced with coalbed methane cbm from the upper cretaceous ferron sandstone member of the mancos shale in east central utah to better understand coalbed methane reservoirs the ferron coalbed methane play currently has more than 600 wells producing an average of 240 bbl day well water water samples collected from 28 wellheads in three fields buzzards bench drunkards wash and helper state of the northeast southwest trending play were analyzed for chemical and stable isotopic composition water produced from coalbed methane wells is a na cl hco3 type water from the drunkards wash field has the lowest total dissolved solids tds 6300 mg l increasing in value to the southeast and northeast in the helper state field about 6 miles northeast water has the highest total dissolved solids 43 000 mg l and major ion abundance indicates the possible influence of evaporite dissolution or mixing with a saline brine in the southern buzzards bench field water has variable total dissolved solids that are not correlated with depth or spatial distance significant differences in the relative compositions are present between the three fields implying varying origins of solutes and or different water rock interactions along multiple flow paths stable isotopic values of water from the ferron range from 0 9 to 11 4 18o and 32 to 90 2h and plot below the global meteoric water line gmwl on a line near but above values of present day meteoric water isotopic values of ferron water are consistent with modification of meteoric water along a flow path by mixing with an evolved seawater brine and or interaction with carbonate minerals analysis of isotopic values versus chloride conservative element and total dissolved solids concentrations indicates that recharge water in the buzzards bench area is distinct from recharge water in drunkards wash and is about 3 c warmer these variations in isotopes along with compositional variations imply that the ferron reservoir is heterogeneous and compartmentalized and that multiple flow paths may exist

cadmium deposition and mobility in the sediments of an acidic oligotrophic lake abstract a dated core from the profoundal zone in a pristine oligotrophic acidic lake was analyzed for cd as well as for al ca fe mg mn pb ti and total carbon and nitrogen overlying water and porewater samples were also obtained on six occasions at the same site and yielded vertical profiles of ph and dissolved cd ca fe mg mn sulfide so 4 2 organic and inorganic carbon concentrations these extensive porewater and sediment geochemical data were used together with information on infaunal benthos to decipher the sedimentary record of cd contamination depth variation of sediment ca concentrations indicate that the lake suffered from progressive acidification starting about 1950 the present day accumulation rate of cd j acc cd 5 4 0 4 10 11 mol cm 2 yr 1 in the sediments is the sum of the flux of cd deposited with settling particles j s cd 3 3 0 2 10 11 mol cm 2 yr 1 and the fluxes of dissolved cd across the sediment water interface due to molecular diffusion j d cd 1 8 0 3 10 11 mol cm 2 yr 1 bioturbation j b cd 1 1 0 2 10 14 mol cm 2 yr 1 and bioirrigation j i cd 0 27 0 05 10 11 mol cm 2 yr 1 biological mixing of the sediments was negligible the shape of the vertical profile of total cd concentration with depth in the sediment appears to be determined more by its input history than by post depositional mobilization and redistribution in the sediment column

kerogen maturation data in the uinta basin utah usa constrain predictions of natural hydrocarbon seepage into the atmosphere natural seepage of methane from the lithosphere to the atmosphere occurs in regions with large natural gas deposits according to some authors it accounts for roughly 5 of the global methane budget i explore a new approach to estimate methane fluxes based on the maturation of kerogen which is the hydrocarbon polymer present in petroleum source rocks and whose decomposition leads to the formation of oil and natural gas the temporal change in the atomic h c ratio of kerogen lets us estimate the total carbon mass released by it in the form of oil and natural gas then the time interval of active kerogen decomposition lets us estimate the average annual formation rate of oil and natural gas in any given petroleum system which i demonstrate here using the uinta basin of eastern utah as an example obviously this is an upper bound to the average annual rate at which natural gas seeps into the atmosphere after adjusting for biooxidation of natural gas i conclude that the average annual seepage rate in the uinta basin is not greater than 3100 900 tonne yr 1 this is 0 5 0 15 of the total flux of methane into the atmosphere over the basin as measured during aircraft flights i speculate about the difference between the regional 0 5 and the global 5 estimates

thallium diagenesis in lacustrine sediments dated sediment cores and porewaters from two canadian shield lakes located 40 km from quebec city l tantare and 25 km downwind from an important smelter in northwestern quebec l vose were analyzed for thallium and other geochemical variables atmospheric deposition is the only source of anthropogenic tl to these lakes the porewater tl concentration profiles in l tantare display a peak below the sediment water interface that suggests post depositional tl remobilization and transport to the overlying water and deeper sediments such a dissolved tl peak occurs just above the sediment water interface in l vose modeling the porewater tl profiles with a diagenetic reaction transport equation reveals a zone of dissolved tl production lying above a zone of tl consumption in l tantare sediments in contrast in l vose tl diffuses across the sediment water interface from the anoxic hypolimnion and is fixed to the surficial sediments the localization of the consumption zones the shape of the dissolved tl sulfide and iron profiles as well as calculations of saturation states are all consistent with the removal of tl from porewater by co precipitation with and or adsorption to fe sulfides the concentrations of tl removed from or added to sediments after their deposition i e diagenetic tl amount to up to 36 of measured sediment tl concentrations comparison of the reconstructed historical tl records with those of polycyclic aromatic hydrocarbons pahs and of pb originating from coal burning or from smelting activities indicate that coal combustion is the major source of atmospheric tl to l tantare and that an additional important tl source to l vose is the nearby smelter

alluvial cutoffs as indicators of former channel conditions although alluvial cutoffs record accurately the geometry bedforms and bed material of the channel when last active few attempts have been made to use cutoffs in studies of channel changes a detailed record of historical channel changes on the lower hunter river in southeastern australia has shown that this channel responds to naturally alternating periods of high and low flood activity called flood and drought dominated regimes respectively sinuosity decreased from 3 84 in 1870 to 2 66 in 1893 and to 1 38 in 1970 through the development of eight cutoffs the channel also aggraded with medium sand burying the former bed material of mixed mud coarse sand and gravel channel straightening was a response to increased flood frequencies during the flood dominated regimes of the late 19th and 20th centuries combined with localized river engineering works and increased sand load detailed stratigraphic studies were carried out on three neck cutoffs and one chute cutoff which were abandoned in 1890 1950 1952 and 1956 a comparison of former and present bed elevations and bed material size showed similar trends to those determined by the historical record confirming the reliability of cutoffs as indicators of former channel conditions the sedimentary infills of the cutoffs are not uniformly fine grained as recorded previously in the literature relatively thin fine grained fills were deposited during the drought dominated regime of the first half of this century but thick coarser grained fills were deposited after 1949 during the flood dominated regime all fills fine upwards cutoff infills provide a record of changing flood activity and sediment loads

hydrocarbon generation as a mechanism for overpressuring in rocky mountain region overpressured reservoirs are present in the deeper parts of most basins in the rocky mountain region a variety of conditions can cause overpressuring however most high pressures in the region are caused by present day or recently active oil and gas generation or generation in the last few million years in low permeability rock successions that still contain organic matter capable of yielding thermally generated hydrocarbons rocks with above normal pressure range from devonian to tertiary and commonly are associated with low permeability tight reservoirs most of the overpressuring occurs in cretaceous and tertiary rocks overpressuring in rocks older than cretaceous is rare and where present only occurs in strata with very rich hydrocarbon source beds such as the d vonian mississippian bakken formation most organically lean pre cretaceous source beds are no longer capable of yielding enough hydrocarbons to maintain abnormal pressure nearly all overpressured reservoirs and source rocks have temperatures of approximately 200 f 93 c or higher in addition available data indicate that hydrocarbon related overpressuring does not generally occur if vitrinite reflectance ro values are less than 0 6 in oil prone strata or less than 0 7 in gas prone strata overpressured gas bearing strata generally have ro values of 0 8 or higher maximum reservoir pressures are about equal to the fracture gradient pressure in the reservoir rocks some vertical fractures in reservoir rocks are probably caused by rapid expulsion of hydrocarbons from the source beds high pressures in the rocky mountain region means that the rock succession is gas or oil saturated and discrete hydrocarbon water contacts are generally not present classical concepts of hydrodynamics do not appear to be applicable to these overpressured successions the optimum depths for exploration are generally the upper 1 000 2 000 ft 305 610 m of the overpressured succession

use of fallout 137cs in investigations of overbank sediment deposition on river floodplains abstract river floodplains have been recognised as important sinks for storing suspended sediment and associated contaminants mobilised from the upstream catchment however information on contemporary rates of overbank sedimentation is difficult to obtain using conventional methods measurements of the 137cs content of floodplain sediments provide an alternative approach to obtaining estimates of medium term rates ca 40 years of overbank sediment deposition the 137cs approach requires only a single site visit and minimum sample preparation furthermore it is capable of providing information on spatial patterns of sediment deposition on floodplains which is needed to improve our understanding of the processes involved in overbank flow and sediment deposition this paper reviews the basis for using 137cs measurements in floodplain sedimentation studies and presents improved procedures for interpreting 137cs profiles in floodplain sediments and for obtaining estimates of sedimentation rates from single measurements of the total 137cs inventories of bulk sediment cores the results obtained from a case study undertaken on the floodplain of the river stour dorset uk are presented

recent sedimentation in three adjacent fjord lakes on the quebec north shore eastern canada facies analysis laminae preservation and potential for varve formation this paper analyzes short gravity cores sampled along transects in three adjacent deep fjord lakes lakes pentecote walker and pasteur on the quebec north shore eastern canada in order to evaluate the distribution of laminated sediments and potential for varve formation facies analysis based on lithological description digital photos ct scan images and bathymetric data allowed for the identification of four main sediment facies namely laminated sediments partially laminated sediments bioturbated sediments and massive sediments direct evidence that lake walker undergoes thermal stratification was monitored from 2014 2016 mean sedimentation rates and sedimentation fluxes of postglacial sediments in the distal basin of the three studied lakes are 1 and 0 03 0 16 g cm 2 a 1 respectively based on 210 pb 137 cs and ams radiocarbon dating on the basis of thin section image analysis and 210 pb cic chronology model lake

dating floodplain sediments using tree ring response to burial floodplain sediments can be dated precisely based on the change in anatomy of tree rings upon burial when a stem of tamarisk tamarix ramosissima or sandbar willow salix exigua is buried subsequent annual rings in the buried section resemble the rings of roots rings become narrower vessels within the rings become larger and transitions between rings become less distinct we combined observations of these changes with tree ring counts to determine the year of deposition of sedimentary beds exposed in a 150 m long trench across the floodplain of the rio puerco a rapidly filling arroyo in new mexico this method reliably dated most beds thicker than about 30 cm to within a year of deposition floodplain aggradation rates varied dramatically through time and space sediment deposition was mostly limited to brief overbank flows occurring every few years the most rapid deposition occurred on channel margin levees which migrated laterally during channel narrowing at the decadal timescale the cross section average sediment deposition rate was steady but there was a shift in the spatial pattern of deposition in the 1980s from 1936 to 1986 sediment deposition occurred by channel narrowing with little change in elevation of the thalweg after 1986 sediment deposition occurred by vertical aggradation from 1936 to 2000 about 27 per cent of the arroyo cross section filled with sediment the rate of filling from 1962 to 2000 was 0 8 vertical m decade or 85 m2 decade published in 2005 by john wiley sons ltd

210pb derived chronology in sediment cores evidencing the anthropogenic occupation history at corumbatai river basin brazil activity profiles of excess 210pb combined with chemical data determined in two sediment cores from corumbatai river basin sao paulo state brazil provided new insights into the reconstruction of historical inputs of anthropogenic constituents contributing to improving management strategies of the hydrological resources in the basin since most of the municipalities extensively utilize the waters of corumbatai river and tributaries for drinking purposes among other uses excellent significant relationships between loss on ignition loi and organic matter were found for sediments of both analyzed profiles silica was found to be inversely related to organic matter at both analyzed profiles its decrease accompanied an increase in the specific surface of the sediments this relationship was confirmed by a great number of inverse significant correlations among silica and oxides na2o k2o cao mgo al2o3 p2o5 fe2o3 mno and tio2 it was possible to identify the role of organic matter on adsorption of several oxides elements in the core sediments profiles apparent sediment mass accumulation rates corresponding to 224 and 802 mg cm 2 year 1 were obtained and are compatible with field evidence indicating a higher value associated with sand mining activities interfering with the natural normal sedimentation process due to modifications of the channel drainage

sediment accretion and organic carbon burial relative to sea level rise and storm events in two mangrove forests in everglades national park abstract the goal of this investigation was to examine how sediment accretion and organic carbon oc burial rates in mangrove forests respond to climate change specifically will the accretion rates keep pace with sea level rise and what is the source and fate of oc in the system mass accumulation accretion and oc burial rates were determined via 210pb dating i e 100 year time scale on sediment cores collected from two mangrove forest sites within everglades national park florida usa enhanced mass accumulation accretion and oc burial rates were found in an upper layer that corresponded to a well documented storm surge deposit accretion rates were 5 9 and 6 5 mm yr 1 within the storm deposit compared to overall rates of 2 5 and 3 6 mm yr 1 these rates were found to be matching or exceeding average sea level rise reported for key west florida organic carbon burial rates were 260 and 393 g m 2 yr 1 within the storm deposit compared to 151 and 168 g m 2 yr 1 overall burial rates the overall rates are similar to global estimates for oc burial in marine wetlands with tropical storms being a frequent occurrence in this region the resulting storm surge deposits are an important mechanism for maintaining both overall accretion and oc burial rates enhanced oc burial rates within the storm deposit could be due to an increase in productivity created from higher concentrations of phosphorus within storm delivered sediments and or from the deposition of allochthonous oc climate change amplified storms and sea level rise could damage mangrove forests exposing previously buried oc to oxidation and contribute to increasing atmospheric co2 concentrations however the processes described here provide a mechanism whereby oxidation of oc would be limited and the overall oc reservoir maintained within the mangrove forest sediments

resource assessment perspectives for unconventional gas systems concepts are described for assessing those unconventional gas sys tems that can also be defined as continuous accumulations contin uous gas accumulations exist more or less independently of the wa ter column and do not owe their existence directly to the buoyancy of gas in water they cannot be represented in terms of individual countable fields or pools delineated by downdip water contacts for these reasons traditional resource assessment methods based on es timating the sizes and numbers of undiscovered discrete fields can not be applied to continuous accumulations specialized assessment methods are required unconventional gas systems that are also continuous accumu lations include coalbed methane basin centered gas so called tight gas fractured shale and chalk gas and gas hydrates deep basin and bacterial gas systems may or may not be continuous accumu lations depending on their geologic setting two basic resource assessment approaches have been em ployed for continuous accumulations the first approach is based on estimates of gas in place a volumetric estimate of total gas in place is commonly coupled with an overall recovery factor to nar row the assessment scope from a treatment of gas volumes residing in sedimentary strata to a prediction of potential additions to re serves the second approach is based on the production perfor mance of continuous gas reservoirs as shown empirically by wells and reservoir simulation models in these methods production characteristics as opposed to gas in place are the foundation for forecasts of potential additions to reserves

extensive microbial modification of formation water geochemistry case study from a midcontinent sedimentary basin united states the upper devonian antrim shale in the michigan basin is an economically significant source of microbially produced methane along the basin margins where meteoric recharge has been focused oxygen and hydrogen stable isotope compositions of antrim formation waters show that fresh waters recharged from pleistocene glaciation and modern precipitation suppressed basinal brine salinity to great depths and enhanced methanogenesis this paper presents results of integrated elemental and isotope analyses of antrim shale formation waters from the margins and center of the michigan basin focusing on solute sources and geochemical modifications associated with regionally extensive microbial methanogenesis cl br na systematics reveal that salinity is controlled not only by mixing between variable amounts of basinal brine and meteoric water but also by halite dissolution where fluids recharged through underlying devonian carbonate aquifers with localized evaporite deposits divalent cations carbonate system parameters and carbon isotope compositions of dissolved inorganic carbon have been systematically and profoundly altered by microbial methanogenesis large decreases in formation water ca mg and ca sr ratios accompany increasing carbonate alkalinity values in areas with high rates of microbial gas production thermodynamic and reaction path modeling show that these changes are consistent with calcite precipitation during progressive microbial methanogenesis similar variations in fluid chemistry are evident in databases from other sedimentary basins containing black shales and coal beds associated with microbial gas microbial methanogenesis may play an important role in the geochemical evolution of divalent cation relationships in crustal fluids and should be considered in models of formation water origin and evolution

effects of storminess sand supply and the north atlantic oscillation on sand invasion and coastal dune accretion in western portugal holocene forested coastal dunes fringe the atlantic coast of western portugal mapping of dunes in the field and using air photographs shows a range of forms reflecting dominant northwest and westerly onshore wind regimes planting of maritime pine forests in the thirteenth and twentieth centuries was initiated because of sand invasion causing problems for human settlement and agriculture early holocene dunes have a well developed podsol and date to 9 7 and 8 2 ka suggesting at least some of these sands may have been emplaced during a global cooling event significant transgressive dune accretion at 2 2 and 1 5 ka implies abundant sand supply and strong onshore winds the most recent dune building period dates to ad 1770 1905 and coincides with a predominantly negative winter north atlantic oscillation index naoi accretion of dunes along the portuguese coast appears out of phase with dune development in southwest france which may reflect different atlantic storm tracks driven by changes in the domin

natural and anthropocene fluxes of trace elements in estuarine sediments of galician rias the anthropocene has been proposed as a new geo stratigraphic epoch where humans have become a global factor affecting the ecosystems estuarine sediments constitute a biogeochemical reservoir where trace elements tes from natural sources mix with a fraction generated by human activities this study assessed the natural lithogenic imprint of tes from uncontaminated sedimentary records to study anthropogenic changes sediment cores were sampled in the estuarine part of the low populated and low industrialized rias of ares a betanzos b and cedeira c which are located in the nw of the iberian peninsula cores were dated by the 210pb method covering up to the last century period sedimentation rates in mm yr 1 were 3 4 0 6 older than 1961 and 8 2 3 2 younger than 1961 for core a 0 9 0 2 1940 and 4 2 2 3 for core b and 13 4 1 4 for core c the background fluxes of tes were in the ranges of in g m 2 yr 1 50 560 for al and fe 20 320 for poc and 8 100 for ps and in mg m 2 yr 1 20 120 for as 0 2 2 0 for cd 7 110 for co 40 870 for cr 20 230 for cu 0 1 0 6 for hg 290 2800 for mn 4 24 for mo 20 410 for ni 20 150 for pb 60 800 for v and 70 700 for zn the three cores showed an anthropogenic influence since the mid 20th century the detected human impact during the anthropocene was due to the eume river damming and as pontes lignite mining the largest mine open pit in the iberian peninsula in core a by bridge road constructions vehicles emissions and river mouth urbanization in core b and changes in land use in core c sediment accumulation rates increased 2 4 core a and 4 7 times core b while tes fluxes increased 2 4 times in core a and between 3 6 and 5 1 times in core b pre industrial sedimentary records showed the lithogenic differences of the drainage basins mainly granitic watersheds for cores a and b and the prevalence of basic rocks of the ortegal geological complex for core c this explains the high concentrations and fluxes of cr ni and v of core c the different lithogenic imprints highlight the value of using local background references in contamination studies such as those on the anthropocene influence in estuaries which occurred after the spanish civil war in the studied rias

genetic characterization of natural gases natural gases can be characterized genetically using four properties c2 concentration carbon and hydrogen isotope variations in methane and carbon isotope variation in ethane three diagrams for genetic characterization of gases have been designed in which the carbon isotopic composition of methane is correlated with the other parameters in these diagrams compositional fields have been defined for primary gases biogenic thermogenic associated and thermogenic nonassociated and for gases which result from mixing of these gases these fields are strictly empirical and comprise compositional variations found in about 500 natural gases the isotopic and compositional variations in natural gases can be described in terms of 1 processes during formation of the gases such as bacterial fermentation or maturation of organic matter and 2 processes during secondary migration mixing of primary gases is an important and common process migration of gases predominantly affects the c2 concentration whereas the isotopic properties of gaseous hydrocarbons primarily remain unchanged allowing an assessment of the origin of migrated gases and properties of their source rocks the formation of gas from humic organic matter and coals is not yet clear from published data the diagrams use data from various basins and areas interstitial gases from the gulf of california are entirely of bacterial origin traces of thermogenic gases are formed only in the vicinity of dolerite sills gases in the south german molasse basin and in the vienna basin are of bacterial mixed and thermogenic origins data from the north italian po basin provide examples for genetic characterization of migrated gases

absence of caesium 137 from recent sediments in eastern australia indications of catchment processes summary sediment and soil containing the isotope caesium 137 137 cs are generally understood to have been sub aerially exposed within the last 35 to 40 years the horizon of first appearance of 137 cs in sedimentary deposits in australia is equated with the mid 1950s the time of first appearance of the isotope in australia some sediments however which are known to have been deposited in alluvial cutoffs since the mid 1950s do not contain the isotope this is interpreted as resulting from the high magnitude of the events which entrained and deposited the sediment the sediment was eroded from sub surface sites and deposited and buried rapidly thereby preventing the adsorption of the isotope the data indicate that 137 cs should be used very cautiously as a dating tool in settings where a good knowledge of the fluvial and sedimentological events accompanying the emplacement of the sediments is not available

depositional setting and diagenetic evolution of some tertiary unconventional reservoir rocks uinta basin utah the douglas creek member of the tertiary green river formation underlies much of the uinta basin utah and contains large volumes of oil and gas trapped in a complex of fractured low permeability sandstone reservoirs in the southeastern part of the basin at pariette bench the eocene douglas creek member is a thick sequence of fine grained alluvial sandstone complexly intercalated with lacustrine claystone and carbonate rock sediments were deposited in a subsiding intermontane basin along the shallow fluctuating margin of ancient lake uinta although the uinta basin has undergone postdepositional uplift and erosion the deepest cored rocks at pariette bench have never been buried more than 9 800 ft 3 000 m the sandstones dominantly lithic arkoses and feldspathic litharenites were derived from source terranes south of the uinta basin secondary silica and several generations of authigenic calcite ca1 8 1 9 mg0 02 0 06fe0 02 0 06 co3 2 dolomite ca1 3 1 4 mg0 6 0 7fe0 02 0 04 co3 2 and ankerite ca1 2 1 3 mg0 2 0 3fe0 4 0 6 co3 2 form a replacive cement in the sandstones commonly syntaxial overgrowths of late iron bearing carbonate occur on detrital grains and preexisting relicts of iron free carbonate cement in sandstone where carbonate has been partly dissolved abundant authigenic illite partly ordered mixed ayer illite smectite and small amounts of chlorite partly to completely fill secondary pores isotopic composition of carbonate cement and grain supported rock range from 0 39 to 6 18 pmil for dgr13c and 7 80 to 13 98 pmil for dgr18o indicating that authigenic carbonate formed at low temperatures in the presence of meteoric waters by a process of solution precipitation enrichment of carbon and oxygen in early diagenetic calcite and fossiliferous rock relative to late diagenetic ankerite indicates a trend toward lighter isotopic carbonate compositions with increasing diagenesis kerogenous rocks at pariette bench are thermochemically immature and therefore are not the source of oil produced in the field hydrocarbons are compositionally similar to some of the oils produced from the green river formation in the bluebell altamont field and are interpreted to have migrated from mature green river source rocks through a network of open fractures the occurrence of small amounts of hydrocarbon in secondary pores indicates that its emplacement postdated carbonate dissolution

time dependent modeling of fallout radionuclide transport in a drainage basin significance of slow erosional and fast hydrological components abstract the sediment depth distributions of 238pu 239 240pu 241am and 137cs have been measured in a sediment core from the saguenay fjord quebec canada which has been dated to better than 1 yr resolution over the past 100 yr using 210pb the historical record of fallout radionuclide fluxes to the sediments has been estimated using a 210pb constant flux model and variations in the flux distributions have been directly related to changes in the atmospheric input function rates of radionuclide transport through the drainage basin have been predicted using a two component time dependent model composed of terrestrial soil and water phases the latter including catchment basins upstream of the fjord the residence times of 137cs and 239 240pu in the soil component are 1000 and 3000 yr respectively while both radionuclides have equivalent residence times of 1 yr in the water column component the atmospheric burn up of a nuclear powered snap 9a satellite in 1964 has resulted in a well defined 238 pu 239 240 pu horizon appearing in the sediments at the 1967 1968 level the magnitude and timing of the snap 9a derived 238pu distribution are in agreement with the drainage basin model predictions and confirm the absence of post depositional remobilization of pu in these anoxic sediment regimes theoretical estimates of the change in the 241 am 239 240 pu activity ratio in sediments deposited since the 1950 s determined using the drainage basin model are in agreement with the experimental results and indicate that the initial 241 pu 239 240 pu activity ratio for the 1950 s weapons tests was 15 or more while the later weapons tests were characterized by an activity ratio closer to 12

mobile mud dynamics in the east china sea elucidated using 210pb 137cs 7be and 234th as tracers mobile mud mm which has fine grain size distribution 90 clay silt and 2 5 in south inshore indicates that the sediment focusing resulted in the increased mass flux the residence time of mm is estimated as 3 6 years both by mass balance of mm and 210pbex in mm

historical change in lake sedimentation in lake takkobu kushiro mire northern japan over the last 300 years abstract environmental degradation including shallowing deterioration of aquatic habitat and water pollution has arisen from the inflow of fine sediment to lake takkobu in northern japan the lake has experienced gradual environmental degradation due to agricultural development which has introduced both fine sediment and sediment associated nutrients into the lake we have reconstructed the history of sediment yield to lake takkobu in kushiro mire over the last 300 years and have examined trends with reference to land use development fifteen lake sediment core samples were obtained and various physical variables of lake sediments were analyzed and dated using 137cs and tephrochronology the physical variables showed that all points contained mainly silt except for two points close to the river mouths where the mean diameter was

interpreting the 137cs profiles observed in several small lakes and reservoirs in southern england abstract the depth distribution of bomb derived 137cs has been studied in cores collected from five small lakes and reservoirs with high sediment accumulation rates in southern england an empirical approach was employed to demonstrate the influence of the catchment derived 137cs input and the post depositional redistribution of 137cs on the 131cs profiles of the sediment cores by incorporating the remobilisation of 137cs and deposited sediment a catchment related 137cs lake deposition model has been used to interpret the 137cs inventories and concentrations in the lake and reservoir sediments in terms of sediment sources a clear linkage between the 137cs concentration in the lake sediment and that in catchment source soils has been established for the five water bodies estimates of the proportion of the total 137cs inventory of individual sediment cores derived from the catchments ranged between 57 and 97 these values emphasise the importance of the catchment derived contribution to the overall 137cs inventory of sediments in small lakes and reservoirs receiving significant sediment inputs from their catchments the estimates of sedimentation rates for the water bodies provided by the cores were also used to estimate the sediment yields from their respective catchments

luminescence dating of holocene sedimentary deposits on romo a barrier island in the wadden sea denmark this study presents an optically stimulated luminescence osl based chronology for the evolution of the barrier island romo and related back barrier lagoon deposits in the danish wadden sea the chronology is constructed using 78 quartz osl ages obtained using a single aliquot regenerative dose sar protocol samples were retrieved from seven sediment cores each up to 25 m long taken from locations on the island and within the back barrier lagoon the reliability of the osl results is assessed using preheat plateaus thermal transfer tests and dose recovery measurements and by comparison with independent age control the osl ages compare favourably with three 14c age estimates and range between 220 20 and 15 800 1200 years romo appears to have developed as a progradational barrier system and the island appeared for the first time approximately 8000 years ago it then gradually expanded towards the west north and south as a result of an abundant sediment supply luminescence dating is concluded t

volumetrically significant recharge of pleistocene glacial meltwaters into epicratonic basins constraints imposed by solute mass balances melting of kilometer thick continental ice sheets during pleistocene glaciation profoundly altered regional scale groundwater flow in the low lying stable interior of the north american craton in this paper we show that large volumes of glacial meltwater penetrated to great depths in underlying sedimentary basins through regionally extensive silurian devonian carbonate aquifers disrupting relatively stagnant saline fluids and creating a strong disequilibrium pattern in fluid salinity these dilute isotopically light meteoric waters migrated into overlying fractured organic rich upper devonian shales and significantly enhanced microbial methanogenesis generating a unique class of natural gas deposits along the shallow basin margins new data on formation water chemistry of upper devonian antrim shale gas wells along the northern and western margins of the michigan basin were integrated with previously published shale data and brines in subjacent silurian devonian carbonates this comprehensive database provides important constraints on fluid and solute transport and makes a compelling case for the reorganization of drinking water resources and salinity structures along the shallow basin margins by pleistocene glaciation na ca cl br relations and mass balance calculations were used to determine the relative volume of meteoric waters and sources of salinity in antrim shale fluids the majority of shale formation waters contain greater than 50 meteoric water with most containing over 80 meteoric water up to 300 m beneath the shale subcrop despite the presence of a strong salinity gradient meteoric water recharge dissolved variable amounts of halite from evaporite bearing silurian devonian carbonates along the flow path into the shale and displaced highly saline nacacl remnant marine brines the majority of antrim shale fluids owe greater than 60 of their salinity to halite dissolution while less than 40 of cl is from mixing with brines in silurian devonian strata oxygen and hydrogen isotope chemistry and carbon 14 age dating indicate these nacl brines were likely generated since the late pleistocene our conceptual model of fluid flow along the michigan basin margins and its role in generation of microbial gas were extrapolated to the larger glaciated midcontinent region where the silurian devonian carbonate subcrop is continuous along the illinois michigan and appalachian basin margins and is overlain by upper devonian black shales major differences in the hydrostratigraphy and fluid salinity of the epicratonic basins controlled the extent of meteoric water invasion and generation of microbial methane increased hydraulic gradients from melting of the continental ice sheets greatly enhanced recharge of dilute waters into deep silurian devonian aquifers and overlying fractured shales reversing regional scale groundwater flow and altering the major ion composition these fluid migration events occurred over relatively short time scales thousands of years compared to well documented basinal scale fluid migration events driven by tectonics and sediment compaction over millions of years understanding the hydrogeochemistry of the saline meteoric water mixing zones and the sources of salinity in sedimentary basins are both important for constraining fluid and solute transport chemical evolution of basinal fluids and physical stability of brines during meteoric water invasion