determination of recent 238u 234u and 230th mobility in granitic rocks application of a natural analogue to the high level waste repository environment abstract the isotope activity ratios 234u 238u and 230th 234u have been investigated in drill core samples up to 1300 m depth in three granitoids from australia to identify the nature of possible recent 1 0 which has generated excess 230th these enriched ground waters do not appear to have penetrated below 530 m depth and 230th excess indicates bulk loss of u the observed disequilibria indicate that significant radionuclide mobilisation has occurred in these rocks during the recent past

electron microprobe and la icp ms study of monazite hydrothermal alteration implications for u th pb geochronology and nuclear ceramics this paper presents new data that quantify the response of magmatic monazite to three main types of hydrothermal alteration namely sericitization chloritization and greisenization the samples were taken from three paleozoic granites the st nectaire granite massif central france the carnmenellis granite cornwall england and the skiddaw granite lake district england fluid inclusion thermometry and hydrothermal parageneses indicate that alteration took place at temperatures ranging from 260 to 340 c and salinities from 3 to 18 wt nacl equivalent possible monazite alteration mechanisms found in the course of this study using backscattered scanning electron microscopy bse sem electron microprobe laser raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry la icp ms include cationic substitutions monoclinic to hexagonal structure transition accompanied by chemical exchanges selective th removal dissolution reprecipitation and dissolution with replacement by a different mineral these results show that despite the compositional and crystallographic simplicity of monazite it exhibits varied chemical responses to different mineral fluid interactions elemental and isotopic measurements by la icp ms for the unaltered monazites yield statistically significant 232th 208pb and 238u 206pb magmatic crystallization ages in some cases it was possible to give a reasonable estimate of the age of mineral fluid interaction using the altered parts of the monazites or newly precipitated crystals for other minerals 232th 208pb and 238u 206pb systematics were strongly disturbed by variable inputs and or depletions of u th and pb the data suggest that monazite like nuclear waste forms would be good hosts for tetravalent actinides but may release the lanthanides and actinides with lower and higher valencies especially if the fluids are oxidizing or tend to dissolve monazite

iodine 129 87sr 86sr and trace elemental geochemistry of northern appalachian basin brines evidence for basinal scale fluid migration and clay mineral diagenesis evidence for basin scale brine migration and clay mineral diagenesis in the northern appalachian basin was investigated using elemental and isotope 129i i 87sr 86sr geochemistry of formation waters collected from the middle to upper devonian section of the northern basin margin in western new york northwest pennsylvania and eastern kentucky one sample from each of the mississippian berea sandstone and the silurian medina sandstone were analyzed for comparison measured iodine ratios range between 28 to 1 890 10 15 and are anomalously high compared to cosmogenic iodine sourced from devonian age organic matter iodine 129 in the waters was largely derived from fissiogenic sources the spontaneous fission of 238u to produce 129i with estimated 129i i values up to 270 10 15 which occur locally in the organic rich shales there are three water samples that have values of 490 10 15 860 10 15 and 1 890 10 15 which are above the range for local fissiogenic 129i and may be accounted for by topographically driven basin scale fluid flow through a regionally high fissiogenic source relatively large uranium occurrences lie along the structural front of the appalachian basin in the blue ridge province and are situated within hypothesized flow paths parallel to the main compressional direction of the alleghanian orogeny estimated 129i i values for these uranium occurrences are in excess of 55 000 10 15 the strontium isotope composition and sr concentration of brines display a mixing trend between a highly radiogenic end member 0 7210 with low sr 51 mg l and a non radiogenic 0 7100 high sr 4789 mg l end member potassium and boron concentrations are notably depleted relative to evaporated paleozoic seawater the hypothesized source of appalachian basin brines the k rb values of formation waters are depleted relative to seawater values but in some cases are well above values indicative of water rock reactions the sr isotopic composition k and b depletion and intermediate k rb ratios are consistent with smectite diagenesis and paleo temperatures that are likely greater than approximately 150 c these temperatures may be high given the burial history of the study area and support the flow of formation waters from deeper within the basin the combined isotopic and elemental results of formation waters provide compelling evidence for basin scale fluid migration in the northern appalachian basin and are consistent with previously published evidence documented from the rock record including clay mineral diagenesis and ore deposition

fission track analysis of uranium distribution in granitic rocks abstract the natural uranium concentration and distribution in three granitoids from australia has been used to develop an understanding of the geochemical processes which control its behaviour in the natural environment and the potential behaviour of some analogue elements within a crystalline high level radioactive waste hlw repository environment in the coles bay granite olympic dam granite and the kambalda granodiorite fission track micromapping has been used to identify primary and secondary distribution between four main mineralogical locales 1 background u 2 resistate u 3 secondary u and 4 fracture u minor concentrations of total u are present as background u in the major rock forming minerals whereas resistate u contributed by the accessory minerals comprises up to 60 of total u two modes of redistribution of primary u are evident 1 in the secondary minerals particularly fe and ti hydroxides and 2 on alteration minerals which infill microfractures the association of u with these secondary and fracture infilling minerals indicates that it has been redistributed during post magmatic hydrothermal alteration and possibly by recent groundwater rock interaction the most important geochemical processes involved in this u redistribution include mobilisation and fixation through complex decoupling and redox reactions and retention by secondary minerals through adsorption and ionic exchange the effect of these processes upon natural u redistribution may be considered as an analogue of geochemical processes around a hlw repository this work shows that a degree of post magmatic alteration of a granite increases the proportion of secondary minerals of high sorption capacity present which may thus enhance the radionuclide retardation capability of the granitoids

radioactive disequilibria in mineralised fracture samples from two uranium occurrences in northern sweden abstract mineralised fractures from two uranium occurrences in northern sweden were examined mineralogically and isotopically to establish the presence or absence of radioactive equilibrium that may indicate recent rock water interaction processes based on the natural mobility of uranium i e during the last 0 5 ma the results show evidence of radioactive disequilibrium in six of the nine samples investigated disequilibria are attributable to solution to solid 234 u recoil gain weakly mineralised zones adjacent to the main mineralisation and solid to solution 234 u recoil loss moderate to highly mineralised zones the absence of significant 238 u loss in the samples emphasises the reducing conditions at the sampled depths

daytime heat transfer processes related to slope flows and turbulent convection in an idealized mountain valley abstract the mechanisms governing the daytime development of thermally driven circulations along the transverse axis of idealized two dimensional valleys are investigated by means of large eddy simulations in particular the impact of slope winds and turbulent convection on the heat transfer from the vicinity of the ground surface to the core of the valley atmosphere is examined the interaction between top down heating produced by compensating subsidence in the valley core and bottom up heating due to turbulent convection is described finally an evaluation of the depth of the atmospheric layer affected by the slope wind system is provided

constraints on the development of secondary porosity in the subsurface re evaluation of processes abstract secondary porosity formed by the dissolution of grains and cements is of great economic importance in both clastic and carbonate reservoirs a review of the commonly proposed mechanisms for the production of secondary porosity indicates that meteoric water penetration and mixing corrosion may be able to create significant volumes of secondary porosity in the shallow subsurface leaching by acidic fluids generated by solution of co 2 or monocarboxylic acids both derived during the thermal maturation of organic matter or by acidic fluids created by clay mineral reactions in shales are the most commonly proposed mechanisms by which secondary porosity is said to form in the deep subsurface however these mechanisms suffer from great difficulties in producing significant volumes of secondary porosity once mass balance and fluid migration problems are taken into account it is highly likely that the correct mechanism for the creation of economically significant amounts of secondary porosity in the deep subsurface is yet to be found

c s fe relationships and the isotopic composition of pyrite in the new albany shale of the illinois basin u s a the relationship between pyritic sulfur content spyr and organic carbon content corg of shales analyzed from the new albany group depends upon corg for samples of 6 wt no spty corg correlation is apparent the degree of fe pyritization dop shows similar relationships to corg these c s fe relationships suggest that pyrite formation was limited by the availability of metabolizable organic carbon in samples where corg 6 wt apparent sulfur isotope fractionations relative to contemporaneous seawater sulfate 34s for pyrite formation average 40 for non calcareous shales and 25 for calcareous shales 34s values become smaller with increasing corg spyt and dop for all corg poar 6 wt and some corg nch 6 wt shales these trends suggest that pyrite formation occurred in a closed system or that instantaneous bacterial fractionation for sulfate reduction decreased in magnitude with increasing organic carbon content the isotopic trends observed in the new albany group are not necessarily representative of other shales having a comparable range of organic carbon content e g cretaceous shales and mudstones from the western interior of north america gautier 1986 34s values in the remainder of the corg rich new albany group shales are relatively large 38 to 47 and independent of corg spyr and dop which suggests that pyrite in these shales formed mostly at or above the sediment water interface by precipitation from an isotopically uniform reservoir of dissolved h2s

provenance tectonic setting and age of the sediments of the upper disang formation in the phek district nagaland abstract integrated petrographic and geochemical studies of sandstones and geochemical studies of shales of turbidites from the upper disang formation phek district nagaland have been carried out to determine their provenance weathering conditions and tectonic setting paleomagnetic studies were carried out for magnetostratigraphic purposes studies indicate that most of these sediments were derived from felsic and mafic sources with minor contribution from low to medium grade metamorphic rocks most of the felsic components have been transported from distant sources as evidenced from extensive reworking of grains the most likely source rocks are the granite granite gneiss of the karbi anglong crystalline complex to the west of the study area however the bulk of the sediments have been contributed from nearby basic and ultrabasic sources this would correspond to the fast rising naga ophiolite which probably emerged above sea level during the mid eocene prevailing high temperatures and humid climate caused intense chemical weathering of the source rocks the sediments from the west were transported great distances by turbidity currents into an easterly deepening basin sediments from the nearby east were rapidly dumped on the seafloor causing rapid mixing leading to textural and chemical immaturity paleomagnetic studies endorse published paleontological evidence to indicate that most of the sediments of the upper disang formation were deposited during the late eocene deposition took place in a westward migrating accretionary prism complex in an active margin setting at the convergence of the indian and burma plates this was a rapidly closing basin where anoxic conditions prevailed towards the end of the eocene this basin closed completely with the destruction of the tethyan ocean

biogenic origin of intergrown mo sulphide and carbonaceous matter in lower cambrian black shales zunyi formation southern china abstract the lower cambrian zunyi formation in southern china hosts complex intergrown phases of mo sulphides and anthracite like carbonaceous matter and graphite mosc pyrite and ni sulphides these sulphides occur in a few centimeters thick polymetallic stratiform layer in black shales above phosphorites cherts dolomites and barite the ore horizon contains 7 wt mo 2 wt ni 19 wt s and 13 wt c org and c tot co 2 58 wt 14 wt cao 1 2 wt as 2000 ppm se 5400 ppm zn 450 ppm u and v and up to 1 ppm platinum group elements three types of mosc phases always including framboidal pyrite are distinguished 1 rounded structures few hundred microns large 2 relict inclusions in diagenetic pyrite 3 grains interstitial to sulphurised and phosphatised organic matter at the nanoscale mosc is represented by nanometric porous rounded structures of mos 2 finely intergrown with carbonaceous matter of typical nano onion structures mosc also contains nanocrysts of quartz clays ca sulphate carbonate and ni sulphides micro raman spectroscopy shows that the carbon phase has a maturation grade of anthracite indicating temperatures below 300 c mosc is mainly composed of 25 wt mo 23 wt s 5 6 wt fe 2 5 wt ni 33 wt c 1 5 wt o 0 6 wt n and several hundreds of ppm of cu as se sb pd zn co and sn electron energy loss spectra show that n is related to nanosized carbonaceous matter the mean c n ratio 57 of mosc is similar to those observed in marine organic matter and those reported from zooplankton at hydrothermal vents the mineralized shales are crosscut by hydrothermal veins composed of carbonate or barite always associated with quartz apatite and fe and zn sulphides a paragenesis also observed as nanocrysts in mosc although mo originated from seawater its extreme concentration is due to an enhanced growth of bacterial consortia in a diffuse hydrothermal vent system these consortia may be dominated by nitrogen fixing and mo dependant hyperthermophilic or mesophilic species containing nitrogenase composed also of mo s fe organic matter decay led thus to the formation of mosc and the included framboidal pyrite

weathering of the new albany shale kentucky usa i weathering zones defined by mineralogy and major element composition abstract comprehensive understanding of chemical and mineralogical changes induced by weathering is valuable information when considering the supply of nutrients and toxic elements from rocks here minerals that release and fix major elements during progressive weathering of a bed of devonian new albany shale in eastern kentucky are documented samples were collected from unweathered core parent shale and across an outcrop excavated into a hillside 40 year prior to sampling quantitative x ray diffraction mineralogical data record progressive shale alteration across the outcrop mineral compositional changes reflect subtle alteration processes such as incongruent dissolution and cation exchange altered primary minerals include k feldspars plagioclase calcite pyrite and chlorite secondary minerals include jarosite gypsum goethite amorphous fe iii oxides and fe ii al sulfate salt efflorescence the mineralogy in weathered shale defines four weathered intervals on the outcrop zones a c and soil alteration of the weakly weathered shale zone a is attributed to the 40 a exposure of the shale in this zone pyrite oxidization produces acid that dissolves calcite and attacks chlorite forming gypsum jarosite and minor efflorescent salt the pre excavation active weathering front zone b is where complete pyrite oxidation and alteration of feldspar and organic matter result in increased permeability acidic weathering solutions seep through the permeable shale and evaporate on the surface forming abundant efflorescent salt jarosite and minor goethite intensely weathered shale zone c is depleted in feldspars chlorite gypsum jarosite and efflorescent salts but has retained much of its primary quartz illite and illite smectite goethite and amorphous fe iii oxides increase due to hydrolysis of jarosite enhanced permeability in this zone is due to a 14 loss of the original mass in parent shale denudation rates suggest that characteristics of zone c were acquired over 1 ma compositional differences between soil and zone c are largely attributed to illuvial processes formation of additional fe iii oxides and incorporation of modern organic matter

hydrological and reactive processes during rapid recharge to fracture zones the aspo large scale redox experiment abstract the hydrochemical response of fracture zones to enhanced recharge into the upper bedrock environment has been studied during a 3 a project at the aspo hard rock laboratory hrl in southeastern sweden hydrochemical data obtained during the experiment provides a basis for development of a model for the impact of accelerated recharge on groundwater composition and reactive processes during repository construction and operation tunnel construction at the hrl resulted in a 50 fold increase in recharge rates and a 30 fold decrease in groundwater residence times in the fracture zone studied up to 80 dilution of the native groundwater created the greatest impact on groundwater composition in addition comparison of mass balances for solutes with known conservative behaviour and reactive solutes indicates a significant source of hco 3 so 2 4 and na ions and a significant sink for ca 2 ions within the fracture zone these trends are explained by ion exchange processes and microbial degradation of organic c transported from the soil with recharge the increased microbial activity helps maintain anoxic conditions within the fracture zone the enhanced recharge favours the performance of the geological barrier since anoxic conditions help to protect against corrosion of engineered barriers and because long lived isotopes of np tc and u are less soluble under reducing conditions a secondary impact is the strong dilution which affects trace element speciation and also the stability and possible transport of colloids through ion strength effects results from this experiment are primarily significant for national radioactive waste disposal programs that consider potential repository sites in granite geology and for other programs considering disposal in fractured rock

long term redox evolution in granitic rocks modelling the redox front propagation in the rock matrix advanced plans for the construction of a deep geological repository for highly radioactive wastes from nuclear power plants have evolved during the past decades in many countries including sweden as part of the swedish concept the waste is to be encapsulated in canisters surrounded by low permeability backfill material the copper canisters will be deposited at around 500 metres depth in granitic rock which acts as a natural barrier for the transport of radionuclides to the ground surface these natural and engineered barriers are chosen and designed to ensure the safety of the repository over hundred of thousands of years one issue of interest for the safety assessment of such a repository is the redox evolution over long times an oxidising environment would enhance the corrosion of the copper canisters and increases the mobility of any released radionuclides in the first part of the present thesis the ability of the host rock to ensure a reducing environment at repository depth over long times was studied a model framework was developed with the aim to capture all processes that are deemed to be important for the scavenging of intruding oxygen from the ground surface over long times simplifications allowing for analytical solutions were introduced for transparency reasons so that evaluation of results is straight forward and so that uncertain parameter values easily can be adjusted more complex systems were solved numerically for cases when the analytical simplifications are not applicable and to validate the simplifications underlying the analytical solutions results were presented for prevailing present day conditions as well as for conditions deemed to be likely during the melting phase of a period of glaciation it was shown that the hydraulic properties have a great influence on the oxygen intrusion length downstream along flow paths in the rock an important parameter that determines the extent of interaction between the dissolved oxygen and the reducing minerals in the rock was shown to be the flow wetted surface to flow rate ratio the results show that for an initial period of time depending on the amount of reducing minerals and reaction rates chemical reaction kinetics may control the rate of the overall depletion of oxygen for longer times internal diffusion resistance in large particles or in the rock matrix become rate limiting for the overall process it was found that there are many uncertainties that have to be considered in order to make reliable quantitative predictions on the extent of oxygen intrusion in the second part of the thesis the impact of intruding oxygen on the corrosion of the copper canisters was explored also a mechanism for the production of sulphide close to the deposition holes was studied sulphide is another corroding agent that may be produced microbially in a reducing environment from sulphate in the presence of organic reductants such as methane from calculation results it was found that corrosion of more than 50 kg of copper is not likely over a period of one million years

physicochemical conditions of sedimentation of the fish clay from stevns klint denmark and its detrital nature vanadium and other supportive evidence cretaceous tertiary k t boundary samples of the fish clay in denmark from three sites stevns klint nye klov and dania have been analyzed mineralogically and chemically all samples contain major amounts of biogenic calcite and smectite in some samples minor amounts of authigenic pyrite and siderite stevns klint and lepidocrocite dania are also present to obtain an indication of the chemical nature of the v present in the danish boundaries the samples were analysed for v and vanadyl vo2 at various stages of selective leaching the results obtained indicate that the bulk of v is associated with the smectite fractions 47 of total v all vo2 resides in the smectite portions from the chemistry of vo2 pyrite and carbonates it is deduced that the oxidation potential and ph of the interstitial seawater of the stevns klint boundary was approximately 0 0 to 0 2 v and 6 to 7 respectively during the accumulation of the lower black basal part but rose during the accumulation of the upper grey part the geochemical data do support the hypothesis that the danish boundary smectite represents weathered clay along with some asteroid and local material that was redeposited to the danish boundary sites after the k t event substantial proportions of the vo2 contents of the nye klov and dania smectite were probably already contained in the detrital clay arriving at the site of boundary sedimentation but at the stevns klint site they have been significantly augmented by uptake from the interfacial and interstitial seawaters through the humic substances involvement abundances and major mineralogical residences have been determined for trace metals cr ni co and ga and minor fe much of these elements is located in the boundary smectite structure as the corresponding ionic forms croh2 ni2 co2 ga3 and fe3 and is strictly detrital in character i e having been transported to the danish boundary sites already contained in smectite all these metals in the danish boundary smectite are well above normal abundances in clays

hydrographic conditions of the devono carboniferous north american seaway inferred from sedimentary mo toc relationships abstract deepwater anoxia developed widely within a series of silled intracratonic basins in north america during the middle devonian to early carboniferous but the hydrographic factors contributing to this development are virtually unknown the present study demonstrates that the degree of enrichment of strongly hydrogenous elements such as molybdenum mo in the organic rich shales that accumulated in these basins has the potential to provide information about paleohydrographic conditions most of the study units 49 of 55 exhibit significant positive covariation between elemental mo and toc concentrations yet there is substantial variation in the statistical parameters that define these relationships specifically the regression lines characterizing mo toc covariation have slopes m ranging from 2 to 65 10 4 although a majority of the study units yield m values between 10 and 25 10 4 the parameter m exhibits systematic stratigraphic variation within individual basins and geographic variation among basins suggesting that mo toc relationships were controlled by slowly evolving watermass characteristics of the devono carboniferous north american seaway a recent study of modern anoxic silled basins algeo t j lyons t w 2006 mo total organic carbon covariation in modern anoxic marine environments implications for analysis of paleoredox and paleohydrographic conditions paleoceanography 21 pa1016 doi 10 1029 2004pa001112 demonstrated that m is closely linked to the degree of restriction of the subpycnoclinal watermass as reflected in aqueous mo concentrations mo aq and deepwater renewal times dw these relationships reflect control of sedimentary mo enrichment by both the amount of sedimentary organic matter i e host phase availability and the concentration of aqueous mo i e source ion availability when applied to black shales of the devono carboniferous north american seaway these relationships permit both qualitative and quantitative inferences regarding the degree of restriction of deepwaters in cratonic basins and the evolution of hydrographic conditions through time black shales associated with early stages of sea level rise commonly exhibit low m values 1000 yr higher sea level stands resulted in more open marine conditions and enhanced deepwater renewal leading to deposition of black shales with m values up to 65 equivalent to mo aq 70 of the normal seawater concentration and dw

an alternative scaling for unsteady penetrative free convection 1 the daytime evolution of the atmospheric boundary layer under high pressure anticyclonic synoptic systems over a homogeneous terrain can be successfully described by a penetrative free convection model evolving from an initially stably stratified environment in this article dimensional analysis has been employed to derive a new set of scaling parameters which are functions of external time dependent fluid properties and boundary conditions this novel theoretical framework has been adopted to compare laboratory scale experiments performed using a thermally controlled water tank and a large eddy simulation les numerical model both these have been developed for the characterization of the instabilities associated with the development of the convective boundary layer cbl the characteristic length and time scales of the thermal plumes their spatial distribution and interaction with the overlying stable layer are analyzed the proposed scaling parameters appear to be representative of the bulk and turbulent properties of the cbl as confirmed by both numerical and laboratory results

environmental analysis of paleoceanographic systems based on molybdenum uranium covariation abstract modern low oxygen marine systems exhibit patterns of molybdenum uranium covariation that can be linked to specific attributes and processes of the depositional system including 1 variation in benthic redox conditions 2 the operation of particulate shuttles within the water column and 3 the evolution of watermass chemistry the importance of these factors in each depositional system can be assessed both from the degree of enrichment of authigenic molybdenum mo auth and uranium u auth and from the mo u auth ratio of the sediment relative to the seawater mo u molar ratio of 7 5 7 9 in open ocean systems with suboxic bottomwaters u auth enrichment tends to exceed that of mo auth owing to onset of u auth accumulation at the fe ii fe iii redox boundary resulting in sediment mo u auth ratios less than that of seawater as bottomwaters become increasingly reducing and at least occasionally sulfidic the rate of accumulation of mo auth increases relative to that of u auth and sediment mo u auth ratios equal or exceed that of seawater in restricted marine systems with permanently sulfidic deepwaters the relative enrichment of mo auth and u auth depends on additional factors in the cariaco basin which has an aqueous mo u ratio similar to that of seawater the operation of a particulate mn fe oxyhydroxide shuttle serves to accelerate the transfer of mo to the seafloor leading to strong enrichments in mo auth relative to u auth in the black sea the chemistry of the deep watermass has evolved to the point where its aqueous mo u ratio is only 0 04 that of seawater as a consequence of which sediments deposited under deepwater influence are depleted in mo auth relative to u auth these mo u covariation patterns can be used to gain a better understanding of the watermass attributes and processes of ancient low oxygen marine systems analysis of anoxic facies from two north american paleomarine systems the late pennsylvanian midcontinent sea lpms and the late devonian seaway lds reveals authigenic mo u relationships similar to those of the modern marine environments above implying similar redox and hydrographic controls the observed patterns are consistent with laterally unconfined circulation and strong watermass exchange within the lpms and with markedly restricted deepwater circulation in silled basins of the lds patterns of authigenic mo u covariation may prove useful in analysis of other paleoceanographic systems to reveal aspects of watermass composition and environmental dynamics

on the boundary layer structure over highly complex terrain key findings from map within map one of the scientific projects was devoted to boundary layers in complex terrain in a number of subprojects boundary layer issues were addressed and detailed high resolution multi sensor observations were combined with simulation by models allowing for adequate parametrization of turbulence processes in this contribution the projects are briefly introduced and an attempt is made to summarize their key findings and to put them into a joint perspective spatial variability is found to be large but strictly related to topography and therefore allowing for possible parametrization traditional boundary layer scaling approaches cannot simply be applied over highly complex topography but some of the map findings suggest the potential for suitable extensions of those scaling relations to cover various cases of complex terrain the mean boundary layer structure and thermally driven flows in narrow valleys are found not to be generally in line with previous results from larger valleys elsewhere furthermore local circulations are reported to contribute considerably to exchange between valley and free troposphere in particular the range of their effects on the lower atmosphere seems to be larger than just turbulent transport within the planetary boundary layer would suggest thus in larger scale numerical models where the topography is not resolved possible sub grid parametrizations for local exchange seem to be in order copyright 2007 royal meteorological society

anoxia and fluctuating climate recorded from the devonian carboniferous black shales tethys himalaya india a multi proxy approach due to inaccessibility and tough conditions high altitude low oxygen region very less information is available about the indian tethys himalayan sequences particularly geochemical data are scarce an attempt is made in the present study to evaluate the sediment geochemistry and paleo redox conditions of devonian carboniferous black shales from the spiti region tethys himalaya using multi proxy approach besides black shales this paper also provides the first in depth study of the geochemistry of phosphatic nodules hosted by the black shales that will allow primary and secondary processes to be understood geochemical investigations particularly redox sensitive trace element ratios for e g v v ni 0 5 ni co 4 3 7 2 v cr 2 and positive ce anomalies suggest deposition of these black shales under sub oxic to anoxic marine conditions thus recording an ocean anoxic event in the region these ocean anoxic events of devonian carboniferous spiti black shales which possess distinctive geochemical signatures can very well be correlated with global events such as hangenberg events and the lower alum shale event the span of the chemical index of alteration cia values 54 78 variation of 4si parameter 82 3 and c values 0 1 0 6 recorded in the black shales strongly indicate varying degrees of weathering conditions in the source area which in turn reflect fluctuating climatic conditions prevailing during the deposition of these sediments in devonian carboniferous period in the spiti region the distinct geochemical characteristics such as y sr and rare earth element ree enrichments particularly middle ree enrichments with a hat shaped pattern with high p2o5 contents up to 14 wt distinguish the nodules from the host rocks black shales sem scanning electron microscope results supplemented by xrd x ray diffraction studies of the nodules show the dominance of calcium silica and phosphatic phases the diversity of clay minerals significant variations in mineralogical composition and lack of any continuous vertical trend in the nodules suggest a relatively low impact on the primary environmental signal by burial diagenesis

analysis of second order moments in surface layer turbulence in an alpine valley the paper presents the analysis of field measurements in the atmospheric surface layer over the floor of the adige valley near the city of bolzano in the alps turbulence quantities such as drag coefficient displacement height and roughness length appear similar to those reported in the literature concerning surface layer turbulence over flat uniform terrain the analysis of the non dimensional standard deviations u v w legitimates the adoption for all the wind components of the same monin obukhov similarity relationship in the form originally proposed only for flat uniform terrain under steady state conditions and the extension of this expression to the case of winds over a valley floor in slowly varying situations the coefficients i are very similar for along valley and cross valley winds as are the i ones moreover the u values are only slightly larger than the v contrary to what is reported in the literature conversely shows distinctly different behaviour in the stable and unstable regimes in particular in the latter case a large scatter in the data is observed however since the most scattered data turn out to occur in transition periods i e sunrise and sunset after a specific data selection the best fit parameters are more accurately estimated in addition emphasis is laid on the relevance of an appropriate formulation and use of a suitable recursive filter to separate the low frequency unsteadiness of the mean flow from the turbulence signal copyright 2009 royal meteorological society

water tank studies of atmospheric boundary layer structure and air pollution transport in upslope flow systems 1 heated mountain slopes sometimes vent air pollutants out of the boundary layer over the slope top and at other times trap pollutants in closed circulations field numerical and water tank studies of fair weather atmospheric conditions over complex terrain have shown more complicated vertical distributions of temperature moisture and aerosols than over horizontal terrain to study these phenomena we analyze flow fields densities and dye distributions in a bottom heated salt stratified water tank over a 19 slope with adjacent plain and plateau and compare with field and numerical model data vertical layering of dye results from upslope and plain plateau circulations the thermal boundary layer tbl the bottom layer up to neutral buoyancy height coincides with the lower branches of these circulations the return flow branches form elevated layers el with properties intermediate between the tbl and environmental background as heating continues the tbl rapidly entrains the els leading to deeper circulations with new els at greater heights field data suggest that successive formation and entrainment of els occurs at multiple scales in the atmosphere if the aerosol loading of an el is too high to distinguish it from the underlying tbl on lidar backscatter scans then both layers and the associated closed circulation appear embedded in one deep backscatter boundary layer the findings suggest defining the atmospheric boundary layer in complex terrain on the diurnal heating timescale rather than the commonly used 1 hour timescale which is more appropriate for flat terrain we discuss conditions leading to venting versus trapping of air pollutants

geochemie von schwarzschiefern und assoziierten metavulkaniten im bereich der pyritlagerstatte schwarzenbach bei dienten salzburger grauwackenzone osterreich die stratiforme pyritlagerstatte schwarzenbach befindet sich innerhalb der palaozoischen vulkanosedimentaren abfolge der wildschonauer schiefer in diesem teil der salzburger grauwackenzone sind den wilschonauer schiefern die aus peliten phyllite tonschiefer mit ubergangen zu psammiten und psephiten bestehen basische vulkanite doleritische sills und tuffe sowie karbonate und schwarzschiefer eingeschaltet die gesamte afolge wurde mehrfach schwachgradig metamorph uberpragt

the provenance of low calcic black shales the elemental concentration of sedimentary rocks depends on the varying reactivity of each element as it goes from the source through weathering deposition diagenesis lithification and even low rank metamorphism however non reactive components of detrital particles ideally are characteristic of the original igneous source and thus are useful in provenance studies to determine the source of detrital granitic and volcanic components of low calcic 1 caco3 marine black shales the concentrations of apparently non reactive i e unaffected by diagenetic redox and or low rank metamorphic processes trace elements were examined using standard trace element discrimination diagrams developed for igneous rocks the chemical data was obtained by neutron activation analyses of about 200 stratigraphically well documented black shale samples from the cambrian through the jurassic a la th sc ternary diagram distinguishes among contributions from the upper and bulk continental crust and the oceanic crust taylor and mclennan 1985 all the low calcic black shales cluster within the region of the upper crust th hf co ternary diagrams also are commonly used to distinguish among the upper and bulk continental crust and the oceanic crust taylor and mclennan 1985 as co is redox sensitive in black shale environments it was necessary to substitute an immobile element i e example rb in the diagram with this substitution of black shales all cluster in the region of the upper continental crust to determine the provenance of the granitic component pearce et al 1984 plots of ta vs yb and rb vs yb ta shows a cluster at the junction of the boundaries separating the volcanic arc granite vag syn collision granite syn colg and within plate granite wpg fields the majority fall within the vag field there are no occurrences of ocean ridge granite org the minimal contribution of basalts to marine black shales is confirmed by the ternary wood diagram th hf 3 ta wood et al 1979 the black shales plot in a cluster in a high th region outside the various basalt fields which suggests contribution from the continental crust

radioactive disequilibria and apparent ages of secondary uranium minerals from sweden abstract thorium and uranium nuclides have been measured using high resolution alpha spectrometry in order to examine the potential of secondary uranium minerals for disequilibrium dating purposes mineral ages are proportional to the distance below the bedrock surface minerals coated on the bedrock surface are usually postglacial with apparent ages below 10 000 years minerals collected from cracks and fissures 3 100 mm below the bedrock surface give apparent ages from 14 000 years to equilibrium ages of more than 300 000 years samples from drill cores collected more than one metre below the surface approach equilibrium some mineral samples have lost uranium indicating open system conditions the examined material does not allow the establishment of a definite relationship between glaciation and mineral ages

environmental impact of mineralised black shales abstract black shales are sedimentary rocks containing 0 5 of organic carbon they host polymetallic deposits which have been mined for cu ni zn mn p mo v u au and pge platinum group elements even sub economic occurrences provide potential risk of acid rock drainage when exposed to oxic surface environment the natural acid neutralisation potential varies depending on the adjacent rock units especially on the presence of calcareous rocks the chemical and mineralogical composition of black shale is reflected in the quality of the surface waters and groundwater cu ni pb u and zn are recognised as major pollutants though the environmental impact is characteristically polymetallic just like the black shale occurrences hence the environmental impacts have to be evaluated in each occurrence the proterozoic ni zn cu co deposit at talvivaara finland is reviewed in more detail as an example of a large low grade deposit that is currently exploited with open pit mining and a bioleaching process together with the proterozoic central african copperbelt the cambrian u mo deposits in sweden the cambrian ni mo pge deposits in china and the cambrian ordovician u deposits in south korea the devonian ni zn pge occurrences in yukon canada and kentucky usa and the permian cu ag deposits in poland and germany the mineralised horizons may be merely few centimetres thick like in yukon or hundreds of metres thick like at talvivaara both natural and anthropogenic environmental impacts of black shales are reviewed world wide and based on the overview of the state of the art an integrated research approach is suggested for the comprehensive assessment of the risk black shales are natural sources of soil and water contamination at talvivaara the geochemical background includes higher than average concentrations of ni cu zn and mn in glacial till peat surface waters and groundwater as well as in stream and lake sediments bioaccumulation by plants has been reported in china and korea even endemic diseases have been proposed to be linked with the contamination derived from the weathering and leaching of harmful elements from black shale anthropogenic actions exposing the black shale bedrock and associated soils to oxic conditions further intensifies acid rock drainage regional or nation wide mapping of the black shales is recommended to detect potential risk areas finland has recently completed the country wide mapping program of black shales with airborne geophysics integrated with geological petrophysical and geochemical studies the black shale database is actively used in regional planning and by environmental authorities research institutes and consulting companies in the case of the historical black shale mining areas like in the kupferschiefer in germany restoration measures have been applied to prevent further acid mine drainage in active and future mining projects a comprehensive environmental impact assessment with effective monitoring programmes and closure plans play a crucial role in the prevention of acid mine drainage from the black shale associated deposits

mineralogy and trace element geochemistry of gas shales in the united states environmental implications abstract this paper presents a compilation of published mineralogic and trace element data from nine gas shales in the united states formations analyzed include the antrim bakken barnett eagle ford haynesville marcellus new albany utica and woodford these mineralogic and trace element data can be used to assess the potential for environmental impacts during hydraulic fracturing impacts addressed in this study include 1 the potential for acid rock drainage generation during gas shale weathering 2 the distribution of trace elements in gas shales and comparison with regulatory guidelines and 3 the implications for environmental management of well cuttings the use of the mineralogic data to assess the fracability of the gas shales is also considered compilations of the mineralogy and geochemistry of gas shales can be a valuable resource for managing real and perceived environmental problems associated with their exploitation comprehensive environmental assessment to fully address these issues in addition to other potential environmental impacts will require collection and collation of additional data on the mineralogy and trace element geochemistry of gas and other hydrocarbon producing shales

daytime development of the boundary layer over a plain and in a valley under fair weather conditions a comparison by means of idealized numerical simulations abstractthe daytime thermal structures of the valley boundary layer vbl and of the convective boundary layer cbl above a plain as revealed by idealized large eddy simulations are compared simulations in the two environments consider similar thermal forcing thus allowing an analysis of the atmospheric heating processes in the vbl and cbl in light of the volume effect theory traditionally invoked to explain the larger diurnal temperature ranges observed in valleys it is found that after an equal input of thermal energy the atmospheric volumes affected by thermal perturbations in the cbl and in the vbl are comparable although the boundary layer top is higher in the vbl than in the cbl the average vbl depth is approximately equal to the cbl depth since the ground elevation is nonuniform in the valley accordingly the volume averaged potential temperature increments in the cbl and vbl are comparable nevertheless surface air temperature variations are larger in the vbl while differences in th

palaeo oceanography and biogeography in the tremadoc ordovician iapetus ocean and the origin of the chemostratigraphy of dictyonema flabelliforme black shales high concentrations of vanadium molybdenum uranium arsenic antimony with low concentrations of manganese iron and cobalt heretofore restricted to dictyonema flabelliforme bearing tremadoc black shales in balto scandia have been found in coeval black shales in the saint john new brunswick area prior palaeogeographic reconstructions place these areas about 400 km apart in high southern latitudes in the iapetus ocean with new brunswick in proximity to avalonia southeastern newfoundland these geochemical similarities are not found in coeval tremadoc black shales of bolivia new york quebec wales and belgium palaeo oceanographic reconstructions of iapetus support the proximity of balto scandia and the saint john area during the early tremadoc and gee sx 1981 suggestion that the signature is a feature of eastern iapetus furthermore first order modelling of the major surface currents and related primary productivity in the tremadoc iapetus ocean explain the apparent wide latitudinal range of d flabelliforme fortey 1984 and the anomalous trace metal content of certain black shales of that time variations in the elemental content of these black shales is produced by oceanographic and geologic conditions unique to the geographic site the distinctive balto scandic geochemical signature resulted from the coincidence of anoxic waters transgressing the shelf at latitudes of high organic productivity at the polar ekman planetary divergence this produces the conditions for concentrations of v u and mo in the shales metal enriched anoxic bottom waters produced by leaching of volcanics or through hydrothermal activity may be the source of the other enhanced signature elements such as as and sb the absence of this geochemical signature in younger non d flabelliforme tremadoc and later black shales in balto scandia and other areas suggests that the closing of iapetus moved the depositional sites into less productive oceanic areas

daytime heat transfer processes over mountainous terrain abstractthe daytime heat transfer mechanisms over mountainous terrain are investigated by means of large eddy simulations over idealized valleys two and three dimensional topographies corresponding to infinite and finite valleys are used in order to evaluate the influence of the along valley wind and the valley surroundings on the heat transfer processes the atmosphere is coupled to an interactive land surface allowing for dynamic feedback on the surface fluxes the valley heat budget is analyzed both from a local and bulk perspective and the flow is reynolds decomposed into its mean and turbulent component the analysis clarifies recent issues of contention regarding the heating of the valley atmosphere the flow decomposition allows one to clearly distinguish between the different heating processes those associated with the mean flow such as advection induced cooling by the upslope flows and the warming induced by the compensating subsidence and those associated with the turbulent motions the

geochemical evidence for the hydrothermal origin of sulphur base metals and gold in proterozoic metamorphosed black shales kainuu and outokumpu areas finland metamorphosed black shale formations 120 150 m thick with median concentrations of 7 non carbonate carbon and 6 8 sulphur are abundantly met in drill cores in the kainuu and outokumpu areas carbon isotope 3c values are comparable to the average isotopic composition of non carbonate carbon in sedimentary rocks the rare earth element patterns show cerium depletion indicating a marine origin base metal concentrations in black shales are high in the talvivaara mineralization ore estimate 300 mt with 0 26 ni 0 14 cu and 0 53 zn and in the vicinity of ophiolite complexes in the kainuu schist belt the median value for gold is 35 ppb max 170 ppb in the western part and 16 ppb max 180 ppb in the east highest platinum and palladium concentrations encountered are 60 70 ppb it is shown that in the kainuu black shales concentrations of sulphur base metals and precious metals have been increased by hydrothermal processes as indicated by positive europium anomalies elevated mercury concentrations max 7 5 ppm high sulphur isotope 34s values and the enrichment of sulphur and base metals relative to carbon the processes operative during the deposition of these shales find an analogy in recent processes in ocean ridge spreading axes

orbitally induced limestone marlstone rhythms in the albian cenomanian cismon section venetian region northern italy sedimentology calcareous and siliceous plankton distribution elemental and isotope geochemistry abstract a multidisciplinary study of the upper albian cenomanian portion of the cismon section venetian region northern italy was undertaken in order to characterize the cyclic alternations of carbonate rich and carbonate poor layers and to investigate their possible origin and cyclic patterns limestone semicouplets are characterized by abundant radiolarians and micarbs micron sized calcitic fragments common planktonic foraminifera strong bioturbation good oxygenation as expressed by the mn and v v ni parameters high si al ratio low k al in the absence of pyrite and organic matter the marlstone semicouplets are on the contrary frequently laminated rich in pyrite and organic matter with common fish remains in the absence of radiolarians the mn and v v ni parameters indicate that the marlstone deposition occurred in dysoxic to anoxic conditions which allowed the preservation of organic matter the low si al ratio and high k al ratio the latter related to abundant feldspars indicate that marlstones received a substantial contribution from a terrigenous source the abundance of biogenic silica suggests that during limestone deposition surface waters were rather fertile due to an efficient recycling of nutrients from deeper waters the enhanced fertility was coupled with an efficient current system at the welloxygenated sea floor which prevented the organic matter from accumulating during marlstone deposition surface waters were less fertile than in the limestone semicouplets but still within the mesotrophic spectrum as indicated by the presence of fertility index species among calcareous nannofossils whereas the bottom waters were oxygen depleted to accommodate fertility at the surface with stagnation at the bottom the scenario implies an enhanced stratification caused by an increase in freshwater runoff monitored by 18o depleted values in the meantime the water discharge supplied the nutrients to the surface waters necessary for the calcareous nannofossils to proliferate the cyclic organization of limestone marlstone couplets as revealed by power spectral analysis seems to represent climatic cycles the alternating conditions are 1 efficient mixing highly fertile surface and near surface waters and a well oxygenated seafloor to 2 enhanced water runoff or decreased evaporation or both and oxygen depleted bottom waters we suggest that this deterministic sedimentary cyclicity could be explained by periodic orbital climatic cycles in tune with the milankovitch cycles within this scenario the latest cenomanian bonarelli level is an exceptional event marked by a large positive 13c spike it is characterized by high to very high fertility conditions in surface waters caused by increased upwelling that engendered high nutrient levels in near surface waters the enhanced production of organic matter was in excess for the oxygen available at the bottom floor thus allowing the organic matter to accumulate in the sediments

some uses for natural analogues in assessing the function of a hlw repository abstract radionuclides migrating with water in a fractured rock may diffuse into the porous matrix of the rock and have access to a very large surface for sorption this will retard their movement very much in excess of what only sorption on the fissure surfaces would do there are some potential natural systems which might be used to show that this process has been active over very long times the transport of u in the bulk rock the salt water content of the micropores of the rock and the interaction of oxygenated water with ferrous minerals in the rock are potential systems to study further a simplified analysis shows that the observed leaching of u in surficial rocks and the observed oxidizing waters in surficial rock is consistent with the assumed diffusion of oxygen into the rock matrix the analysis also shows that the values of observed reducing waters in deeper rock are consistent with the matrix diffusion data oxygenated waters cannot penetrate more than a few meters or tens of meters into rock with the hydraulic properties prevailing at depths below a few hundred meters during several million years of exposure

mechanisms of up valley winds abstract the basic physical mechanisms governing the daytime evolution of up valley winds in mountain valleys are investigated using a series of numerical simulations of thermally driven flow over idealized three dimensional topography the three dimensional topography used in this study is composed of two two dimensional topographies one a slope connecting a plain with a plateau and the other a valley with a horizontal floor the present two dimensional simulations of the valley flow agree with results of previous investigations in that the heated sidewalls produce upslope flows that require a compensating subsidence in the valley core bringing down potentially warmer air from the stable free atmosphere in the context of the three dimensional valley plain simulations the authors find that this subsidence heating in the valley core is the main contributor to the valley plain temperature contrast which under the hydrostatic approximation is the main contributor to the valley plain pressure differe

constraining the timing of microbial methane generation in an organic rich shale using noble gases illinois basin usa abstract at least 20 of the world s natural gas originates from methanogens subsisting on organic rich coals and shales however in situ microbial methane production rates are unknown methanogens in the upper devonian new albany shale in the illinois basin extract hydrogen from low salinity formation water to form economic quantities of natural gas because of this association constraining the source and timing of groundwater recharge will enable estimation of minimum in situ metabolic rates thirty four formation water and gas samples were analyzed for stable isotopes oxygen and hydrogen chloride tritium 14 c and noble gases chloride and 18 o spatial patterns reveal a plume of water with low salinity 0 7 to 2154 mm and 18 o values 0 14 to 7 25 penetrating 1 km depth into evapo concentrated brines parallel to terminal moraines of the laurentide ice sheet suggesting glacial mediated recharge however isotopic mixing trends indicate that the recharge endmember 7 18 o is higher than the assumed bulk ice sheet value 18 o and similar to modern local precipitation 7 5 to 4 5 18 o continental paleoprecipitation records reveal that throughout the pleistocene 18 o of precipitation in the region ranged from 10 to 5 suggesting that the dilute groundwater was primarily sourced from paleoprecipitation with minor contributions from glacial meltwater for the majority of samples the atmosphere derived 4 he contribution is negligible and the 4 he is dominated by a crustal radiogenic source with near complete transfer of dissolved noble gases to the gas phase in addition mantle derived helium is negligible for all samples 18 o data however all groundwater in the study area was influenced by pleistocene recharge estimated in situ microbial methane production rates range from 10 to 1000 tcf ma 10 4 to 10 6 times slower than average laboratory rates from coals findings from this study have implications for targeting undeveloped microbial gas accumulations improving natural gas reservoir estimates the potential of in situ methanogen stimulation and understanding biologic cycling of carbon in subsurface reservoirs

a review of apatites iron and manganese minerals and their roles as indicators of biological activity in black shales abstract biological contribution to the formation of minerals has become more than a descriptive area in geological thought and research mechanisms of specific mineral accumulation and deposition in oceancs lakes and even desert environment are studied using interdisciplinary approaches and applied in the interpretation of earth processes phosphorus iron and manganese are and probably were essential elements in life forms the common minerals of these elements apatite and magnetite for example can be found in a variety of sedimentary environments both ancient and modern where they could be useful indicator minerals to interpret geologic environments the crystal morphological structural and chemical including isotopic attributes of these usually fine grained minerals can be compared with bulk chemical and stratigraphic information to augment our understanding of the mechanisms of formation and diagenesis in sediments such as black shales

comparison of organic geochemistry and metal enrichment in two black shales cambrian alum shale of sweden and devonian chattanooga shale of united states in most black shales such as the chattanooga shale and related shales of the eastern interior united states increased metal and metalloid contents are generally related to increased organic carbon content decreased sedimentation rate organic matter type or position in the basin in areas where the stratigraphic equivalents of the chattanooga shale are deeply buried and and the organic material is thermally mature metal contents are essentially the same as in unheated areas and correlate with organic c or s contents this paradigm does not hold for the cambrian alum shale formation of sweden where increased metal content does not necessarily correlate with organic matter content nor is metal enrichment necessarily related to land derived humic material because this organic matter is all of marine source in southcentral sweden the elements u mo v ni zn cd and pb are all enriched relative to average black shales but only u and mo correlate to organic matter content tectonically disturbed and metamorphosed allochthonous samples of alum shale on the caledonian front in western sweden have even higher amounts for some metals v ni zn and ba relative to the autochthonous shales in this area and those in southern sweden

clay mineralogy and unconventional hydrocarbon shale reservoirs in the usa i occurrence and interpretation of mixed layer r3 ordered illite smectite abstract the mineralogy of many of the major unconventional hydrocarbon shale reservoirs in the usa which span practically the whole spectrum of phanerozoic time is reviewed from a survey of relevant published literature this survey reveals that there is a remarkable uniformity in the mineralogy of these shales both with regard to non clay minerals but particularly to the clay minerals it was found that the clay mineralogy of practically all of the shale reservoirs older than the upper cretaceous are dominated by illitic clays both in discrete form and as illite dominated mixed layer illite smectite i s the layer stacking arrangement of the latter is of the long range type described as r3 such that every smectite layer tends to be preceded and succeeded by three illite layers in a sequence like iiisiiis such material is conventionally interpreted a as having formed from a smectite precursor b as existing in macewan type crystallites consisting of about 5 to 15 unit layers in thickness where there is three dimensional regularity across the smectite interlayers and c as having interlayers of a truly smectitic character using evidence from the fundamental particle concept of nadeau et al 1984b this interpretation is rejected instead it is proposed that r3 type i s a forms de novo crystallizing from pore waters of appropriate chemical composition in a particular pressure and temperature stability field as it does in conventional sandstone reservoirs b consists primarily of thin illite crystallites or crystals

chemical and mineralogical analysis of devonian black shale samples from martin county kentucky carroll and washington counties ohio wise county virginia and overton county tennessee u s a abstract core samples of devonian shales from five localities in the appalachian basin have been analyzed chemically and mineralogically the amounts of major elements are similar however the minor constituents organic c s phosphate and carbonate show ten fold variations in amounts trace elements mo ni cu v co u zn hg as and mn show variations in amounts that can be related to the minor constituents all samples contain major amounts of quartz illite two types of mixed layer clays and chlorite in differing quantities pyrite calcite feldspar and kaolinite are also present in many samples in minor amounts dolomite apatite gypsum barite biotite and marcasite are present in a few samples in trace amounts trace elements listed above are strongly controlled by organic c with the exception of mn which is associated with carbonate minerals amounts of organic c generally range from 3 to 6 and s is in the range of 2 5 amounts of trace elements show the following general ranges in ppm parts per million co 20 40 cu 40 70 u 10 40 as 20 40 v 150 300 ni 80 150 high values are as much as twice these values the organic c was probably the concentrating agent and the organic c and sulfide s together created an environment that immobilized and preserved these trace elements closely spaced samples showing an abrupt transition in color also show changes in organic c s and trace element contents several associations exist between mineral and chemical content pyrite and marcasite are the only minerals found to contain sulfide s in general the illite chlorite mixed layer clay mineral shows covariation with organic c if calcite is not present the enriched trace elements are not related to the clay types although the clay and organic matter are intimately associated as the bulk fabric of the rock

structure of the entrainment zone capping the convective atmospheric boundary layer the authors use large eddy simulation les to investigate entrainment and structure of the inversion layer of a clear convectively driven planetary boundary layer pbl over a range of bulk richardson numbers ri the les code uses a nested grid technique to achieve fine resolution in all three directions in the inversion layer extensive flow visualization is used to examine the structure of the inversion layer and to illustrate the temporal and spatial interaction of a thermal plume and the overlying inversion it is found that coherent structures in the convective pbl that is thermal plumes are primary instigators of entrainment in the ri range 13 6 ri 43 8 at ri 5 13 6 strong horizontal and downward velocities are generated near the inversion layer because of the plume interface interaction this leads to folding of the interface and hence entrainment of warm inversion air at the plume s edge at ri 5 34 5 the inversion s strong stability prevents folding of the interface but strong horizontal and downward motions near the plume s edge pull down pockets of warm air below the nominal inversion height these pockets of warm air are then scoured off by turbulent motions and entrained into the pbl the structure of the inversion interface from les is in good visual agreement with lidar measurements in the pbl obtained during the lidars in flat terrain field experiment a quadrant analysis of the buoyancy flux shows that net entrainment flux or average minimum buoyancy flux wu min is identified with quadrant iv w2u1 0 motions that is warm air moving downward plumes generate both large negative quadrant ii w1u2 0 and positive quadrant iii w2u2 0 buoyancy fluxes that tend to cancel the maximum vertical gradient in potential temperature at every x y grid point is used to define a local pbl height zi x y a statistical analysis of zi shows that skewness of zi depends on the inversion strength spectra of zi exhibit a sensitivity to grid resolution the normalized entrainment rate we w where we and w are entrainment and convective velocities varies as ari21 with a 0 2 in the range 13 6 ri 43 8 and is in good agreement with convection tank measurements for a clear convective pbl the authors found that the finite thickness of the inversion layer needs to be considered in an entrainment rate parameterization derived from a jump condition

physical mechanisms of the thermally driven cross basin circulation the physical mechanisms responsible for the formation of a thermally driven cross basin circulation in a basin with asymmetric heating of opposite mountain sidewalls are investigated a large eddy simulation is performed with the weather research and forecasting model for an idealized basin based on the topography of arizona s meteor crater the individual components of the horizontal momentum and thermodynamic balance equations are analyzed to determine their respective contributions in forcing the cross basin circulation a cross basin pressure gradient with higher pressure on the less irradiated sidewall leads to the development of a cross basin flow near the basin floor a weak opposing return flow develops above this cross basin flow as a result of a reversed cross basin pressure gradient the reversed cross basin pressure gradient is caused by cold air advection by upslope winds in the stable morning atmosphere on the sunlit sidewall and warm air advection by downslope winds on the still shaded sidewall as this reverses the cross basin temperature gradient producing a higher temperature on the less sunlit sidewall

the thermally driven diurnal wind system of the adige valley in the italian alps the adige valley is one of the major corridors connecting the po plain with the inner alps a series of permanent weather stations and one wind profiler provide a regular monitoring of air temperature atmospheric pressure global solar radiation wind speed and direction over the 140 km valley length and in the adjacent plain data from these stations are analysed for a subset of days on which weather conditions favoured a full development of diurnal valley winds in the period 2012 2014 the analysis highlights typical features in the alternating patterns of diurnal up valley winds and nocturnal down valley winds in particular the wind intensity depends linearly on the along valley pressure gradient supporting the concept of a quasi steady balance between pressure gradient and surface friction also in agreement with previous investigations the amplitude of the surface pressure cycle increases in the up valley direction causing the reversal of the horizontal pressure gradient twice per day in contrast no appreciable along valley variation in the diurnal temperature range is found the analysis of surface temperature and pressure measurements suggests that the larger pressure perturbations found far into the valley are caused by the increased depth of the atmospheric layer subject to heating and cooling local inhomogeneities in the valley cross section in particular in the vicinity of a large basin cause temperature and pressure perturbations that are strong enough to alter the typical cycle of down and up valley winds similarly local wind convergence over the major cities during the night are explained in terms of the urban heat island effect

misuse of the term bentonite for ash beds of devonian age in the appalachian basin ash beds of devonian age in the appalachian basin have been incorrectly called bentonites the emphasis placed on the volcanic origin of the beds rather than on their mineralogical and physical characteristics apparently led to the erroneous application of the term bentonite recent study indicates that the lack of smectite in the tioga belpre and center hill bentonite beds compared with the type bentonite warrants the deletion of the term bentonite and the substitution of the term ash it is recommended that the ash beds of devonian age be referred to as the tioga ash bed the belpre ash bed and the center hill ash bed