scale dependence of soil permeability to air measurement method and field investigation this work investigates the dependence of soil permeability to air on sampling scale in near surface unsaturated soils a new dual probe dynamic pressure technique was developed to measure permeability in situ over different length scales and different spatial orientations in the soil soils at three sites were studied using the new technique each soil was found to have higher horizontal than vertical permeability significant scale dependence of permeability was also observed at each site permeability increased by a factor of 20 as sampling scale increased from 0 1 to 2 m in a sand soil vegetated with dry grass and by a factor of 15 as sampling scale increased from 0 1 to 3 5 m in a sandy loam with mature coast live oak trees quercus agrifolia the results indicate that standard methods of permeability assessment can grossly underestimate advective transport of gas phase contaminants through soils

the end permian mass extinction a rapid volcanic co2 and ch4 climatic catastrophe abstract the end of the permian was a time of crisis that culminated in the earth s greatest mass extinction there is much speculation as to the cause for this catastrophe here we provide a full suite of high resolution and coeval geochemical results trace and rare earth elements carbon oxygen strontium and clumped isotopes reflecting ambient seawater chemistry and water quality parameters leading up to the end permian crisis preserved brachiopod low mg calcite based seawater chemistry supplemented by data from various localities documents a sequence of interrelated primary events such as coeval flows of siberian trap continental flood basalts and emission of carbon dioxide leading to warm and extreme greenhouse conditions with sea surface temperatures sst of 36 c for the late permian although anoxia has been advanced as a cause for the mass extinction most biotic and geochemical evidence suggest that it was briefly relevant during the early phase of the event and only in areas of upwelling but not a general cause instead we suggest that renewed and increased end permian siberian trap volcanic activity about 2000 years prior to the extinction event released massive amounts of carbon dioxide and coupled with thermogenic methane emissions triggered extreme global warming and increased continental weathering eventually these rapidly discharged greenhouse gas emissions less than 1000 years before the event ushered in a global hothouse period leading to extreme tropical ssts of 39 c and higher based on these sea surface temperatures atmospheric co 2 concentrations were about 1400 ppmv and 3000 ppmv for the late and end permian respectively leading up to the mass extinction there was a brief interruption of the global warming trend when sst dropped concurrent with a slight but significant recovery in biodiversity in the western tethys it is possible that emission of volcanic sulfate aerosols resulted in brief cooling just after the onset of intensified warming during the end of the permian after aerosol deposition global warming resumed and the biotic decline proceeded and was accompanied by suboxia in places of the surface ocean which culminated in the greatest mass extinction in earth history

distribution of uranium thorium and rare earth elements in the eye dashwa lakes pluton a study of some analogue elements abstract the distribution of u th and rare earth elements ree s in the eye dashwa lakes pluton near atikokan ontario is examined materials analysed include a unaltered granite b altered granite c highly altered granite adjacent to open fractures and d fracture filling minerals distinct distribution patterns are noted for u and some ree s among the four types of samples th shows higher concentrations in materials c and d compared with unaltered and altered granite the highly altered granite and some fracture fillings have greater concentrations of u th and ree s the large concentrations of u th and ree s in these materials are due to both sorption on selective materials and precipitation as mineral phases containing these elements the occurrence of uraninite bastnaesite and thorogummite coatings on fracture fillings are examples of this precipitation

rapid wavelet based bathymetry inversion method for nearshore x band radars abstract a wavelet based method for bathymetry retrieval from x band radar images is proposed the method combines traditional fast fourier transform techniques for retrieving peak frequency maps by evaluating the spectral peaks in the time domain and a localized 2d continuous wavelet transform for retrieving the corresponding peak wavenumbers the main improvements of the new method compared to conventional fft based methods are as follows a the wavelet based approach is localized naturally fitting the inhomogeneous conditions typically found in the nearshore environment b it is continuous and uses wave phase information providing smooth bathymetry maps with good accuracy rmse in the range 2 6 6 6 of the maximum water depth c it requires relatively small number of successive images without the limitation of requiring a uniform time step in order to verify the proposed method 2d simulations of wave shoaling and refraction were performed for different sea conditions and over several bottom topographies a radar image model including tilt and shadowing modulations together with speckle noise was applied to the simulated surface elevations to provide synthetic radar images the method s ability to reconstruct the original bathymetry is shown to be robust in intermediate to shallow water depths kph

carbon isotope stratigraphy across the permian triassic boundary a review abstract the palaeozoic mesozoic transition is marked by distinct perturbations in the global carbon cycle resulting in a prominent negative carbon isotope excursion at the permian triassic p t boundary well known from a plethora of marine and continental sediments potential causes for this negative 13 c trend and their links to the latest permian mass extinction have been intensively debated in the literature in order to draw conclusions regarding causation a general 13 c curve was defined after consideration of all available datasets and with due reference to the biostratigraphic background the most important features of the p t carbon isotope trend are the following the 4 7 13 c decline lasting 500 000 years is gradual and began in the changhsingian at the stratigraphic level of the c bachmanni zone the decreasing trend is interrupted by a short term positive event that starts at about the latest permian low latitude marine main extinction event horizon eh indicating that the extinction itself cannot have caused the negative carbon isotope excursion after this short term positive excursion the 13 c decline continues to a first minimum at about the p t boundary a subsequent slight increase is followed by a second occasionally two peaked minimum in the lower and middle i isarcica zone the negative carbon isotope excursion was most likely a consequence of a combination of different causes that may include 1 direct and indirect effects of the siberian trap and contemporaneous volcanism and 2 anoxic deep waters occasionally reaching very shallow sea levels a sudden release of isotopically light methane from oceanic sediment piles or permafrost soils as a source for the negative carbon isotope trend is questionable at least for the time span a little below the eh and somewhat above the p t boundary

progressive environmental deterioration in northwestern pangea leading to the latest permian extinction stratigraphic records from northwestern pangea provide unique insight into global processes that occurred during the latest permian extinction lpe we examined a detailed geochemical record of the festningen section spitsbergen a stepwise extinction is noted as starting with 1 loss of carbonate shelly macrofauna followed by 2 loss of siliceous sponges in conjunction with an abrupt change in ichnofabrics as well as dramatic change in the terrestrial environment and 3 final loss of all trace fossils we interpret loss of carbonate producers as related to shoaling of the lysocline in higher latitudes in relationship to building atmospheric co 2 the loss of siliceous sponges is coincident with the global lpe event and is related to onset of high loading rates of toxic metals hg as co that we suggest are derived from siberian trap eruptions the final extinction stage is coincident with redox sensitive trace metal and other proxy data that suggest onset of anoxia after the other extinction events these results show a remarkable record of progressive environmental deterioration in northwestern pangea during the extinction crises

flourishing ocean drives the end permian marine mass extinction the end permian mass extinction the most severe biotic crisis in the phanerozoic was accompanied by climate change and expansion of oceanic anoxic zones the partitioning of sulfur among different exogenic reservoirs by biological and physical processes was of importance for this biodiversity crisis but the exact role of bioessential sulfur in the mass extinction is still unclear here we show that globally increased production of organic matter affected the seawater sulfate sulfur and oxygen isotope signature that has been recorded in carbonate rock spanning the permian triassic boundary a bifurcating temporal trend is observed for the strata spanning the marine mass extinction with carbonate associated sulfate sulfur and oxygen isotope excursions toward decreased and increased values respectively by coupling these results to a box model we show that increased marine productivity and successive enhanced microbial sulfate reduction is the most likely scenario to explain these temporal trends the new data demonstrate that worldwide expansion of euxinic and anoxic zones are symptoms of increased biological carbon recycling in the marine realm initiated by global warming the spatial distribution of sulfidic water column conditions in shallow seafloor environments is dictated by the severity and geographic patterns of nutrient fluxes and serves as an adequate model to explain the scale of the marine biodiversity crisis our results provide evidence that the major biodiversity crises in earth s history do not necessarily implicate an ocean stripped of most life but rather the demise of certain eukaryotic organisms leading to a decline in species richness

hydrogeological and geochemical control of the variations of 222rn concentrations in a hard rock aquifer insights into the possible role of fracture matrix exchanges to investigate the possible variations of rn concentration in crystalline rocks as a function of flow conditions a field study was carried out of a fractured aquifer in granite the method is based on the in situ measurement of rn in groundwater aquifer tests for the determination of hydraulic characteristics of the aquifer and laboratory measurement of rn exhalation rate from rocks a simple crack model that simulates the rn concentration in waters circulating in a fracture intersecting a borehole was also tested the rn concentrations in groundwaters from boreholes of the study site ranged from 192 to 1597 bq l 1 the rn exhalation rates of selected samples of granite and micaschist were determined from laboratory experiments the results yielded fluxes varying from 0 5 to 1 3 mbq m 2 s 1 in granite and from 0 5 to 0 9 mbq m 2 s 1 in micaschists pumping tests were performed in the studied boreholes to estimate the transmissivity and calculate the equivalent hydraulic aperture of the fractures transmissivities ranged from 10 5 to 10 3 m2 s 1 using the cubic law hydraulic equivalent fracture apertures were calculated to be in the range of 0 5 2 3 mm to gain a better insight into the spatial variability of rn contents in groundwater theoretical rn concentrations were calculated from an available simple crack model using results from field and laboratory experiments this model gave satisfactory results for boreholes characterized by low flow conditions in which case the calculated rn contents were in the range of rn concentrations set by the analytical uncertainty of concentrations measured in water however for boreholes characterized by high flow conditions the model underestimated the rn concentration in groundwater the higher the flow in the fracture the larger the difference between calculated and measured rn concentrations in water these observations led to performing pumping tests to obtain a better understanding of the hydrogeological control of rn content in water the results clearly show an increase of rn content in groundwater after the pumping test which could be explained by the input of rn rich waters from the host matrix

mapping submarine sand waves with multiband imaging radar 2 experimental results and model comparison on august 16 1989 and on july 12 1991 experiments were performed to study the mapping of submarine sand waves with the airborne imaging radar a polarimetric and in 1991 interferometric airborne p l and c band synthetic aperture radar system the experiments took place in an area 30 km off the coast of the netherlands where the bottom topography is dominated by sand waves with a height between 2 and 6 m and a crest to crest distance of about 400 m at an average depth of 22 m ground measurements were recorded on a nearby platform and on a ship in the test area which also acted as a position fix on august 16 1989 the wind was 5 m s directed toward the northeast while the surface current velocity was around 0 5 m s directed toward the southwest one overflight was made with the flight direction parallel to the sand wave crests and the radar looking upwind at p band the sand waves are clearly visible as dark bands as predicted by theory while at l band the sand waves show up as sawtooth shaped modulations on july 12 1991 wind and surface current had the same opposite directions as in 1989 though the wind was much higher 10 m s three flights were made with the radar pointing upwind cross wind and downwind the upwind and downwind images are very similar despite the high wind speed the sand waves are clearly visible as sawtooth shaped modulations at p band and vaguely visible at l band at c band only wind streaks can be seen all cross wind images show the sand waves as dark bands now with the highest modulations at c band the wind streaks that dominated the upwind and downwind images at c band are much less pronounced in the cross wind images the images are compared with predictions from a new model of the imaging mechanism which includes contribution to the radar cross section of waves moving both from and to the radar wave blocking or wave reflection is treated in an approximate manner for the radar looking upwind or downwind the predicted modulations at p and l band agree well with the observations while those at c band are too high for the radar looking cross wind the model severely underestimates the modulations it is questioned whether a local relaxation source term can describe such a situation the interferogram shows some structure caused by bottom induced surface current variations

environmental instability prior to end permian mass extinction reflected in biotic and facies changes on shallow carbonate platforms of the nanpanjiang basin south china abstract shallow carbonate platforms exhibit major changes in faunal composition and facies types during the latest permian and earliest triassic although the microbialites that developed following the latest permian mass extinction lpme have attracted wide attention temporal variations in shallow platform facies and faunas prior to the lpme have been less thoroughly studied here we analyze diversity patterns and variation in skeletal composition in three upper permian sections from isolated carbonate platforms of the nanpanjiang basin in addition to the well known transition from fossil rich upper permian limestones to fossil poor permian triassic boundary ptb microbialites these sections exhibit several distinct changes that predate the lpme first foram faunas show a shift from non fusulinid dominated to fusulinid dominated communities in the

planar lamellar substructures in quartz both single and multiple sets of lamellar features in quartz grains can be produced in shock experiments and are observed at known impact sites they can also be produced in static constant strain rate experiments and are observed at known tectonic and explosive volcanic sites the former are strictly planar and parallel and generally conform to rational crystallographic orientations in the quartz crystal structure the latter can also be planar and parallel but sometimes show slight to moderate curvature with lamellar bifurcations and variable lamellar widths their orientations show a variety of forms with in general a broader angular distribution than that of the impact generated lamellae deductions of physical conditions of deformation from optical morphology spacing multiplicity and orientation information alone remain somewhat conjectural full characterization by transmission electron microscopy tem appears to be necessary

the implications of laboratory222rn flux measurements to the radioactivity in groundwaters the case of a karstic limestone aquifer laboratory time scale experiments were conducted on carboniferous limestone gravels from the mendip hills area england with the purpose of evaluating the release of 222 rn to the water phase the specific surface areas of the samples were 4 14 and 1 69 cm 2 g 1 which provided respectively values of 50 6 and 12 7 pci for the released rn these results allowed the calculation of the emanation coefficient of this rock matrix with respect to the release of rn where completely different values corresponding to 23 and 6 were found suggesting that the extent to which grain boundaries or imperfections in aggregates of micro crystals of calcite intersect the particle surface certainly affects the rn release they also permitted the evaluation of models for the generation of rn in rocks and transfer to water in order to interpret the radioactivity due to this gas in groundwaters from the karstic aquifer of the mendip hills area where the calculated activities in groundwater based on the values of 23 and 6 for the emanation coefficient were about 51 and 15 times higher than actually measured in groundwater therefore the emanation coefficient in nature is considerably smaller than in the lab experiment and another factor k 0 k 1 may be introduced into the equations related to the modelling with the aim of adjusting the theoretical practical results

222rn transport in a fractured crystalline rock aquifer results from numerical simulations abstract dissolved 222 rn concentrations in ground water from a small wellfield underlain by fractured middle proterozoic pikes peak granite southwest of denver colorado range from 124 to 840 kbq m 3 3360 22700 pci l 1 numerical simulations of flow and transport between two wells show that differences in equivalent hydraulic aperture of transmissive fractures assuming a simplified two fracture system and the parallel plate model can account for the different 222 rn concentrations in each well under steady state conditions transient flow and transport simulations show that 222 rn concentrations along the fracture profile are influenced by 222 rn concentrations in the adjoining fracture and depend on boundary conditions proximity of the pumping well to the fracture intersection transmissivity of the conductive fractures and pumping rate non homogeneous distribution point sources of 222 rn parent radionuclides uranium and 226 ra can strongly perturb the dissolved 222 rn concentrations in a fracture system without detailed information on the geometry and hydraulic properties of the connected fracture system it may be impossible to distinguish the influence of factors controlling 222 rn distribution or to determine location of 222 rn point sources in the field in areas where ground water exhibits moderate 222 rn concentrations flow and transport simulations of a hypothetical multifracture system consisting of ten connected fractures each 10 m in length with fracture apertures ranging from 0 1 to 1 0 mm show that 222 rn concentrations at the pumping well can vary significantly over time assuming parallel plate flow transmissivities of the hypothetical system vary over four orders of magnitude because transmissivity varies with the cube of fracture aperture the extreme hydraulic heterogeneity of the simple hypothetical system leads to widely ranging 222 rn values even assuming homogeneous distribution of uranium and 226 ra along fracture walls consequently it is concluded that 222 rn concentrations vary not only with the geometric and stress factors noted above but also according to local fracture aperture distribution local groundwater residence time and flux of 222 rn from parent radionuclides along fracture walls

distribution of radon sources and effects on radon emanation in granitic soil at ben lomond california the abundance and distribution of radioelements on bulk and microscopic scales were investigated in residual granitic derived soil at a facility for investigating the movement of radon into structures in bulk soil samples ra concentrations range from 0 6 to 1 3 pci g and variations in ra th and k appear to be controlled mainly by heterogeneities inherited from the parent granitic rock which contains abundant dikes and inclusions u in soil and parent rock is concentrated in primary minerals mainly zircon and sphene and in secondary sites that are of greater importance for rn emanation the main u bearing secondary sites are weathered sphene grain boundary coatings weathered biotite and plagioclase as well as dense fe rich coatings and a ree phosphate mineral present in near vertical fracture zones in saprolite underlying shallow loam elevated u in these sites generally correlates with high ti al fe and or p preferential distribution of u and ra on grain boundaries and porous weathered minerals is reflected in relatively high rn emanation rates in the soil highest emanation occurs between 1 3 and 2 3 m depth where fine pedogenic phasesgibbsite and amorphous silica and fe ooh are most abundant it is related to fixation of ra by these phases which precipitate close to the surface and accumulate at these depths by illuviation separation of ra from u may occur locally given remobilization of u series elements from secondary sites and large differences between ra and u sorption capabilities of several phases present in the soil concentration of u along permeable fracture zones in saprolite suggests that contribution of soil gas rn from depth 2 m could be significant to rn availability near the surface

the influence of parent material on topsoil geochemistry in eastern england the topsoil of around 10 000 km2 in eastern england has recently been sampled intensely at 4609 sites to characterize its geochemistry the parent materials which include both solid geology and quaternary sediments range in age from permian to holocene the distributions of the concentrations of major and trace elements have been characterized geostatistically and the role of parent material on their spatial structure anisotropy and their spatial relationships coregionalization have been investigated analysis of variance with the sites grouped by major parent material type showed that this classi cation accounted for 14 to 48 per cent of the variance for the various elements global variograms of 13 elements al as ca cr cu fe mg mo ni p pb ti and u have been computed and modelled eleven of the variograms seem to comprise two structures both of which we modelled with spherical functions one of short range 3 5 to 9 km and the other with a range of 15 to 23 km the models included a nugget variance which varied from 27 per cent for as fe and mg to 63 per cent for p of the total the long range structures are related to the separations of the major parent materials the variograms of several elements showed appreciable anisotropy most notably that of mg anisotropy is evident at short ranges of less than 5 km this accords with the geological structure of the beds which dip from west to east so that their outcrops are elongated from north to south a linear model of coregionalization tted to the data emphasized several important geochemical associations which we interpret elements commonly associated with clay minerals mg al and the clay size fraction ti are dominated by the long range structure of the coregionalization whilst several trace elements as cr ni and u are spatially correlated with fe over short distances through adsorption of the former on the surfaces of fe oxyhydroxides the topsoil around large urban areas is enriched in lead but it is not clear whether anthropogenic sources are responsible for this metal s anomalous spatial relationships with other elements crown copyright 2003 reproduced with the permission of her majesty s stationery of ce published by john wiley sons ltd

a review of the structure petrology and dynamic deformation characteristics of some enigmatic terrestrial structures abstract we review three categories of enigmatic terrestrial structures that have a variety of macroscopic and microscopic dynamic deformation features the first category includes the midcontinent united states cryptoexplosion structures they are of shallow origin and illustrate the effects that might be expected from a meteorite impact on a sedimentary rock terrane the second category includes the well known vredefort and sudbury plutons or basement uplifts the lesser known precambrian basement uplifts at steen river manson and carswell and the diatreme breccia dikes at the slate islands they are of relatively deep seated origin and illustrate the effects that might be expected from deep crustal or mantle processes of an explosive nature the third category includes the large landslides in areas of crystalline rocks at koefels and langtang the dynamic deformation features at these latter locations appear to be related to high strain rate tectonic processes associated with the landslide itself we conclude that microscopic dynamic deformation features which occur in natural materials may have originated from meteorite impacts from internal explosions or from high strain rate tectonic process

recoil emanation theory applied to radon release from mineral grains abstract in this paper the recoil emanation theory is presented as a major mechanism for rn release from solid materials the basic theory is developed for rn emanation from geometrical shapes spheres and cylinders having variable thickness of precursor ra containing material subsequently a sphere pore model of emanation from mineral grains like those in rocks soils etc is developed in this model a surface of the grain is constructed as a superposition of in and out directed spherical caps and cylindrical pores the model incorporates processes like rn embedding pore overlap water effect and emanation from the edges using such a geometrical model it is shown how the rn emanating power measurements can give a clue to the ra distribution and surface properties of the samples in particular it is shown that for grains reasonably larger than the recoil range and for surface ra distribution the emanating power is independent of the grain size but the total ra concentration varies with the reciprocal of the grain size the opposite is true for ra distributed uniformly throughout the volume of the grain it is shown how the rn emanating power is related to the surface porosity of the grain also implications are made with respect to u transport in nature and with respect to low emanating power from lunar soil finally a failure of the emanation theory is discussed to reproduce emanation curves for the samples having high specific surface areas and ra distributed throughout the volume

sea surface current features observed by doppler radar a coherent x band radar was operated from the shore to measure velocities at the sea surface the test site at a tidal inlet lister tief in the german bight lay protected from swell and long wind waves a vertical vertical antenna was used to obtain the backscattered radar signal caused by bragg scattering to cover a sector of the circle the antenna was rotated in 1dstrok steps at each step the data acquisition was performed to obtain a time series of the backscattered radar signal the maximum range is 1905 m with a range resolution of 7 5 m and an azimuthal resolution of 3 5diam maps of the averaged backscattered radar power and radial doppler velocities are obtained the radar backscatter maps show the modulation of the radar cross section due to changes in the surface roughness the radar doppler velocity maps show the modulations of the surface scatterer speed the maps show many features for example the impact of subsurface sand waves eddies current shears slicks ship wakes atmospheric effects and small scale current changes behind sheet pile walls as the radar backscatter is caused by short wind waves the wind influence on the doppler signal was calculated for a first attempt to obtain true current motions the results were compared with in situ current measurements by subsequently measuring the surfaces current from two radar positions and performing the wind correction the current vector fields are assessed

electron microscopy study of hyalomylonites evidence for frictional melting in landslides abstract hyalomylonites from langtang nepal and kofels otz valley austria were investigated by transmission electron microscopy tem the matrix is glassy at both localities rarely it is crystallized and devitrified to dendrites and skeletal microlites of plagioclase alkali feldspar and biotite the matrix is chemically heterogeneous with schlieren and formed by partial to almost complete melting of host rocks of granitic to granodioritic composition locally glasses with pure quartz plagioclase and alkalifeldspar composition were found from sio 2 glass minimum temperatures of 1520 c are estimated at both hyalomylonite localities melting appears to be the result of frictional heating on the gliding plane of a large landslide the host rocks were deformed in a brittle mode microstructures typical of plastic deformation at high temperatures are displayed by inclusions and were probably inherited from previous tectonic events

effective radium 226 concentration in meteorites the analysis of noble gases in meteorites provides constraints on the early solar system and the pre solar nebula this requires a better characterization and understanding of the capture production and release of noble gases in meteorites the knowledge of transfer properties of noble gases for each individual meteorite could benefit from using radon 222 radioactive daughter of radium 226 the radon 222 emanating power is commonly quantified by the effective radium 226 concentration ecra the product of the bulk radium 226 concentration and of the emanation coefficient e which represents the probability of one decaying radium 226 to inject one radon 222 into the free porous network owing to a non destructive high sensitivity accumulation method based on long photomultiplier counting sessions we are now able to measure ecra of meteorite samples which usually have mass smaller than 15 g and ecra 0 5 bq kg 1 we report here the results obtained from 41 different meteorites based on 129 measurements on 70 samples using two variants of our method showing satisfactory repeatability and a detection limit below 10 2 bq kg 1 for a sample mass of 1 g while two meteorites remain below detection level we obtain for 39 meteorites heterogeneous ecra values with mean min max range of ca 0 1 0 018 1 30 bq kg 1 carbonaceous chondrites exhibit the largest ecra values and eucrites the smallest such values are smaller than typical values from most terrestrial rocks but comparable with those from archean rocks mean of ca 0 18 bq kg 1 an end member of terrestrial rocks using uranium concentration from the literature e is inferred from ecra for all the meteorite samples values of e for meteorites mean 40 4 are higher than e values for archean rocks and reported values for lunar and martian soils exceptionally large e values likely suggest that the 238u 226ra pair would not be at equilibrium in most meteorites and that uranium and or radium are most likely not uniformly distributed ecra of meteorites is correlated with e and seems to mainly reflect the gas permeability of the meteorite which could be one important property preserved in the meteorite of its parent body characterizing its history in space possibly modified by alteration shock metamorphism and eventually weathering on earth larger radon emanation values are associated with larger concentrations of the heaviest noble gases argon krypton xenon and larger 20ne 22ne and 36ar 38ar ratios suggesting earth s atmosphere contamination or solar wind implantation and probably a similar carrier phase such as q phase an unclear correlation is observed with 40ar which may rule out a purely radiogenic effect on radon emanation thus larger radon emanation suggests a larger capacity of collecting solar and terrestrial gases which should imply higher loss of gases generated in the meteorite and larger dispersion of pb u ratios for age determination this study provides the first quantification of natural radon 222 loss from meteorites and opens promising perspectives to quantify the relationship between pore space connectivity and the transfer properties for noble gases in meteorites and other extraterrestrial bodies

direct recoil radon emanation from crystalline phases influence of moisture content this paper is devoted to the study of the radon emanation coefficient vs water mass fraction for mineral samples modeling is performed considering only the direct recoil phenomena and assuming planar pores with high lengths to width aspect ratios water is assumed either to fill the pore alternatively with air or to form a continuous film on the pore surface this modeling is applied to uranium mine tailings for which the pore size distribution was experimentally measured it enables a good description of the change of the experimental radon emanation coefficients with the moisture content of the studied samples

planar deformation features in shocked quartz a transmission electron microscopy investigation abstract we present a detailed investigation by transmission electron microscopy tem of the fine structure of planar deformation features pdf in quartz grains within which shock metamorphism has been detected optically and which originate from various sites slate islands la malbaie and manicouagan lake canada ries crater germany the toba caldera sumatra the vredefort complex in south africa and the k t boundary at raton basin colorado pdfs appear on tem micrographs as straight and very narrow tem reveals many more pdfs than are optically detected probably because only concentrations of such defects in narrow areas can induce an optically detectable contrast caution should therefore be exercised when applying criteria based on the optical observation of single or multiple sets of pdfs pdfs in samples from slate islands and raton basin exhibit a peculiar morphology a high density of very tiny bubbles precipitated on the dislocation lines comparison with the behavior of wet quartz strongly suggests that these materials experienced lengthy annealing at moderate pressure and temperature

proximal impact deposits at the cretaceous tertiary boundary in the gulf of mexico a restudy of dsdp leg 77 sites 536 and 540 restudy of deep sea drilling project sites 536 and 540 in the southeast gulf of mexico gives evidence for a giant wave at cretaceous tertiary boundary time five units are recognized 1 cenomanian limestone underlies a hiatus in which the five highest cretaceous stages are missing possibly because of catastrophic k t erosion 2 pebbly mudstone 45 m thick represents a submarine landslide possibly of k t age 3 current bedded sandstone more than 2 5 m thick contains anomalous iridium tektite glass and shocked quartz it is interpreted as ejecta from a nearby impact crater reworked on the deep sea floor by the resulting tsunami 4 a 50 cm interval of calcareous mudstone containing small cretaceous planktic foraminifera and the ir peak is interpreted as the silt size fraction of the cretaceous material suspended by the impact generated wave 5 calcareous mudstone with basal tertiary forams and the uppermost tail of the ir anomaly overlies the disturbed interval dating the impact and wave event as k t boundary age like beloc in haiti and mimbral in mexico sites 536 and 540 are consistent with a large k t age impact at the nearby chicxulub crater

the behavior of u and th series nuclides in groundwater groundwater has long been an active area of research driven by its importance both as a societal resource and as a component in the global hydrological cycle key issues in groundwater research include inferring rates of transport of chemical constituents determining the ages of groundwater and tracing water masses using chemical fingerprints while information on the trace elements pertinent to these topics can be obtained from aquifer tests using experimentally introduced tracers and from laboratory experiments on aquifer materials these studies are necessarily limited in time and space regional studies of aquifers can focus on greater scales and time periods but must contend with greater complexities and variations in this regard the isotopic systematics of the naturally occurring radionuclides in the u and th decay series have been invaluable in investigating aquifer behavior of u th and ra these nuclides are present in all groundwaters and are each represented by several isotopes with very different half lives so that processes occurring over a range of time scales can be studied table 1 within the host aquifer minerals the radionuclides in each decay series are generally expected to be in secular equilibrium and so have equal activities see bourdon et al 2003 in contrast these nuclides exhibit strong relative fractionations within the surrounding groundwaters that reflect contrasting behavior during release into the water and during interaction with the surrounding host aquifer rocks radionuclide data can be used within the framework of models of the processes involved to obtain quantitative assessments of radionuclide release from aquifer rocks and groundwater migration rates the isotopic variations that are generated also have the potential for providing fingerprints for groundwaters from specific aquifer environments and have even been explored as a means for calculating groundwater ages view this table table 1 radionuclides important in groundwater studies the highly fractionated nature of the

dynamic deformation of volcanic ejecta from the toba caldera possible relevance to cretaceous tertiary boundary phenomena plagioclase and biotite phenocrysts in ignimbrites erupted from the toba caldera sumatra show microstructures and textures indicative of shock stress levels higher than 10 gpa strong dynamic deformation has resulted in intense kinking in biotite and with increasing shock intensity the development of plagioclase of planar features shock mosaicism incipient recrystallization and possible partial melting microstructures in quartz indicative of strong shock deformation are rare however and many shock lamellae if formed may have healed during post shock residence in the hot ignimbrite they might be preserved in ash falls peak shock stresses from explosive silicic volcanism and other endogenous processes may be high and if so would obviate the need for extraterrestrial impacts to produce all dynamically deformed structures possibly including shock features observed near the cretaceous tertiary boundary 38 references 3 figures

evaluating the source and seasonality of submarine groundwater discharge using a radon 222 pore water transport model article i nfo pore water radon 222 rn distributions from indian river lagoon florida are characterized by three zones a lower zone where pore water 222 rn and sediment bound radium 226 ra are in equilibrium and concentration gradients are vertical a middle zone where 222 rn is in excess of sediment bound 226 ra and concentration gradients are concave downward and an upper zone where 222 rn concentration gradients are

dynamic deformation of quartz and feldspar clues to causes of some natural crises abstract indications of natural catastrophes and crises are preserved in some geologic strutures and in the stratigraphic record emphasizing the dynamic nature of the earth s evolution the crises may result either from exogenic or endogenic energy sources distinguishing between these sources is a complex multidisciplinary problem in the earth sciences shock deformation by impact has been well studied both in shock recovery experiments and in known impactites but only recently has the possibility of generation of shock waves by high temperature internal explosions been seriously considered an optically based reconaissance survey of microstructures in quartz and feldspar in some explosive silicic volcanics suggests that they may have been induced by dynamic deformation at high temperature in some respects the character of the microstructures differs greatly from those induced by room temperature shock whereas in others the differences are subtle results from recent shock recovery experiments on quartzite preheated to 440 and shocked to 28 gpa support this contention for two classic cretaceous tertiary sections at gubbio italy it is shown that shock mosaicism and shock lamellae occur over a 4 m interval bisected by the boundary in a pattern approximately correlatable with an independently established iridium enrichment these data are incompatible with any single event and are most plausibly interpreted as reflecting a period 0 5 my of intense probably episodic volcanism with a culmination at the k t transition multiple dynamic events may also account for macroscopic and microscopic structures developed during the evolution of the vredefort structure south africa

pedogeochemical models on prognosis and control of radon fluxes from humid tropical landscapes over granite the principal relationships between radon 222rn and 220rn exhalation intensities and the morpho dynamic elements of humid tropical landscapes have been established and analyzed with the objective of elaborating rn exhalation models which can be used on the scale of small habitational nuclei the current radioactive processes of generation emanation and migration of rn in relation to its exhalation rates on a landscape slope of granitic rock having normal u and th contents were correlated with the latosol podzolic soil association developed as a product of supergene processes during geological and pedological times and also with the water regime of an overlying phreatic aquifer this approach encompassing pedogeochemical models of radionuclide dispersion linked to soil systems and surface geochemistry was framed within a tridimensional interdisciplinary and systemic focus using concepts of nuclear physics climate and hydrogeology the characteristic signatures of elementary landscapes include 1 different landforms namely eluvial transeluvial and superaqual 2 residual soils having varying types thicknesses and perma porosities and 3 radioanomalies corresponding to different u and th concentrations secondary hosting minerals and also to different pedological ages considering these factors and their spatial relationships and on the basis of moisture content of soils it is postulated that the highest rn exhalation rates especially of 222rn are confined to superaqual and transeluvial landscapes in an eluvial landscape the rn fluxes are found to be less important even though gamma anomalies exist mainly due to the presence of resistant minerals containing u and th in short the products of supergene alteration organized in a sloping system can exhibit rn exhaling intensities higher than that measured on unaltered subjacent rock

integrated geophysics and soil gas profiles as a tool to characterize active faults the amer fault example pyrenees ne spain the combined use of geophysical and soil gas composition exploration methods allows to rapidly obtain at relative low cost information that might be related to seismic activity conditions in this study we carried out geochemical soil gas sampling 222rn 220rn and co2 electrical resistivity tomography and seismic refraction profiles in two selected zones near the town of amer in the spanish pyrenees where the presence of recent fractures is evident in the field data analysis clearly reveals anomalous values for each gas at specific positions along the electrical imaging transects geomorphologic and hydrogeologic data and the integration of geophysical data and soil gas measurements indicate that 1 endogene gases radon 222rn and carbon dioxide co2 are released from the meta sedimentary basement rocks across the main fractured zones with higher permeability values while lower cenozoic detrital sedimentary formations act as an impervious boundary 2 sites with highest radon concentrations 52 kbq m 3 coincide with the zones in the amer fault showing more recent geomorphic evidence of activity and more specifically with those areas covered by thinner surficial formations 3 the lowest 222rn values 0 2 0 4 kbq m 3 were recorded just on the master active fault plane this pattern could be explained by a dilution effect resulting from high rates of soil co2 efflux 267 g m 2 day 1 4 soil thoron 220rn activity is maximum 143 kbq m 3 in areas with high surficial fracturing 5 groundwater pumping may cause important distortions in the natural flow dynamics and in the measured concentrations of gases the agreement between the different data geochemical geophysical and hydrogeological and field observations geology and geomorphology leads us to propose a preliminary tectonic gravitational model for the study area

the relative mobility of u th and ra isotopes in the weathered zones of the eye dashwa lakes granite pluton northwestern ontario canada radioisotope activity ratios of weathered surface rocks from the eye dashwa lakes granite pluton show that in the 238u decay series 226ra has been leached more rapidly than the grandparent 234u and 238u isotopes the observation of 238th232th disequilibria in the 232th decay series shows that either 228th half life of 1 9 yrs or 228ra half life of 5 75 yrs have been removed from these rocks very rapidly indeed isotope ratios of separated mineral fractions appear to show that whereas uranium tends to be removed from all mineral fractions ra is strongly readsorbed onto feldspars presumably as these undergo alteration to clay minerals this necessitates making a distinction between intermineral mobility of u or ra and the net loss of u or ra from the whole rock an attempt has been made to model quantitatively the transport rate of ra though with little success failure of the modelling appears to indicate that the mobility of 228ra is higher than might be predicted by the mobility of 226ra that is the two isotopes are not strict analogues of one another in their response to initial weathering

mechanisms of radon loss from zircon microstructural controls on emanation and diffusion abstract understanding how radon escapes from minerals is important for many fields in earth science yet few studies have focused on the mechanisms for radon escape we measured radon emanation rate and radon loss upon heating for crushed aliquots of three large zircon crystals from three localities mud tank australia bancroft canada and malawi africa our study in conjunction with published data shows that the room temperature radon emanation coefficient rec varies over 5 orders of magnitude in zircon for low u zircon mud tank there are variations in rec that appear to be related to annealing at different temperatures possibly due to annealing of fission tracks however all rec values for mud tank zircon are within error of one another bancroft and malawi zircons have higher u content and do not show any systematic relationship of rec to annealing temperature results from mud tank zircon suggest that partial annealing of fission tracks decreases rec but when all fission tracks are annealed rec reaches a maximum rec in zircons with high u content bancroft and malawi is slightly higher than in zircon with lower u although results are within error results of measurements of radon loss upon heating suggest that radon diffusion is slow 30 of the radon is lost during heating at 975 c for 48 h samples heated a second time yield less fractional radon loss 10 suggesting that diffusion parameters are changed during heating at temperatures 975 c which is likely the result of annealing of radiation damage diffusion parameters calculated from the fractional loss experiments reflect diffusion in highly radiation damaged or metamict zircons our results indicate that internal microstructures in zircon such as fission tracks and alpha radiation damage influence radon escape for diffusion and recoil mechanisms and hence if these effects can be further characterized measurements of 222rn escape have the potential to be useful for probing the internal structure of zircon and other u bearing minerals

frequent euxinia in southern neo tethys ocean prior to the end permian biocrisis evidence from the spiti region india abstract in this study we reconstruct water column oxygen availability during the deposition of late permian shales wuchiapingian to approximately early changhsingian using the geochemistry and morphology of sedimentary pyrite fes2 deposition of the shales occurred prior to the end permian mass extinction within the southern neo tethys ocean spiti region himachal pradesh india we found that the variability of pyritic sulfur to organic carbon spyr corg and the pyritic sulfur isotopic composition 34spyr did not record changes in oxygen availability at spiti sections this was due to the removal of original pyritic sulfur by modern oxidative weathering and diagenetic pyrite formation which overwhelmed the original 34spyr values however pyrite framboid size distributions was a reliable recorder of paleoredox conditions the degree of oxygen limitation varied with multiple transient euxinic events interrupting a predominantly oxic dysoxic trend near the top of the gungri formation upper member approximately late wuchiapingian to early changhsingian these transient euxinic intervals provide important insight and regional evidence of environmental stress and instability in the southern neo tethys well prior to the end permian mass extinction

comparative study of 222rn 40ar 39ar and 37ar leakage from rocks and minerals implications for the role of nanopores in gas transport through natural silicates we have measured the leakage of radiogenic 222rn and 40ar and reactor produced 39ar and 37ar in samples of granites plagioclase orthoclase cleavelandite and hornblende to assess the role of nanopores in gas transport through them the 39ar and 37ar were produced by fast neutron irradiation of the samples in vacuum sealed ampoules the leakage of all three ar isotopes was barely measurable in contrast the leakage of 222rn ranged between 1 45 18 1 orders of magnitude higher than that of the ar isotopes the extremely low ar isotope leakage suggests that the samples studied are not permeated by extensive nanopore networks which intersect grain surfaces the relatively high 222rn loss from these samples therefore has to be attributed to preferential enrichment of 226ra 238u on grain surfaces or to the existence of u th accessory minerals in or around grain boundaries from which substantial quantities of 222rn escape

effective radium concentration across the main central thrust in the nepal himalayas effective radium concentration ec ra of 622 rock samples from 6 different sites in the nepal himalayas was measured in the laboratory using radon accumulation experiments these sites located from lower dolpo in western nepal to eastern nepal are divided into 9 transects which cut across the main central thrust zone mct zone separating low grade meta morphic lesser himalayan sequence lhs units to the south and higher grade metamorphic greater himalayan sequence ghs units to the north this boundary remains difficult to define and is the subject of numerous debates ec ra values range from 0 03 0 03 to 251 6 4 0 bq kg a1 and appear to be representative of the formation and clearly related to the local lithology for example for the upper trisuli and langtang valleys site in central nepal the most studied place with 350 available ec ra values lhs rocks are characterized by a mean value of 5 3 1 3 bq kg a1 while ghs rocks of formations i and ii show significantly lower values with a mean value of 0 69 0 11 bq kg a1 thus leading to a lhs ghs ec ra ratio of 7 8 2 2 this behavior was systematically confirmed by other transects ratio of 7 9 2 2 in all other sites with a threshold ec ra value separating lhs from ghs of 0 8 bq kg a1 thus bringing forward a novel method to characterize within the mct shear zone which rocks belong to the ghs and lhs units in addition ulleri augen gneiss belonging to lhs rocks occurred in several transects and were characterized by high ec ra values 17 9 4 3 bq kg a1 easy to distinguish from the ghs gneisses characterized by low ec ra values at the bottom of the ghs thus providing a further argument to locate the mct the measurement of ec ra data thus provides a cost effective method which can be compared with neodymium isotopic anomalies or estimates of the peak metamorphic temperature this study therefore shows that the measurements of ec ra provides additional information to discriminate different geological formations and can be particularly useful in areas where geology mapping is not straightforward or still remains controversial

evolution of oceanic redox conditions during the permo triassic transition evidence from deepwater radiolarian facies abstract the 90 biodiversity loss among marine invertebrate species during the end permian mass extinction the most severe phanerozoic biocrisis has been attributed to widespread oceanic anoxia superanoxia recent studies of the lithofacies inorganic geochemistry and biomarkers of permian triassic boundary ptb sections have yielded an inferred pattern of oceanic redox changes that is complex and sometimes inconsistent in this contribution we review the ecology of radiolarians an important microzooplankton group during the permo triassic transition and consider its implications for contemporaneous changes in paleoceanographic conditions our analysis shows that 1 late permian radiolarian faunas were cosmopolitan with different orders having specific depth preferences i e albaillellarians favoring deeper waters and spherical forms entactinarians and spumellarians shallower waters 2 deep water taxa declined earlier than shallow water taxa 3 many paleozoic type taxa survived into the early triassic but went extinct during a second crisis in the dienerian dead clade walking followed by the appearance or expansion of mesozoic type taxa during the olenekian and 4 the survival of paleozoic type taxa during the early triassic was greater at higher paleolatitudes than in the tropics these observations are consistent with a first order redox control on radiolarian faunal distributions specifically a shallowing and poleward expansion of the oceanic oxygen minimum zone during the ptb crisis the consequent adaptation of some deepwater taxa to shallower environments resulted in early triassic radiolarian faunas in continental basins becoming more similar to those in pelagic settings enhanced survival of paleozoic type taxa in high latitude regions indicates that the main stressor on permo triassic radiolarian communities was reduced oceanic oxygen levels stronger in the tropics rather than climatic warming stronger at the poles

222rn and 220rn emanations as a function of the absorbed α doses from select metamict minerals metamict minerals contain uranium and thorium which contribute to physical degradation or metamictization of their crystal structures over geologic time the damage occurs primarily through progressive overlapping recoil nuclei collision cascades from decay of 238u 232th 235u and their daughter products we measured 222rn and 220rn emanations from metamict samples of nine oxides brannerite davidite fergusonites pyrochlores samarskites and uraninite two phosphates monazites and eight silicates cerite gadolinites perrierite rinkite thorite turkestanite and vesuvianite the total absorbed doses ranged from 1 4 1015 to 6 1 1018 decay mg 1 for cerite and uraninite respectively the 222rn emanation coefficients varied from 5 10 5 uraninite to 2 5 turkestanite the 220rn emanation coefficients varied from 7 10 3 gadolinite ytterby to 6 2 gadolinite marysin the lowest 222rn emanation coefficients occurred among metamict minerals containing the highest concentrations of 238u i e uraninite samarskites and brannerite overall the 222rn and 220rn emanation coefficients observed in this study fall significantly below previously reported values

catastrophic dispersion of coal fly ash into oceans during the latest permian extinction the eruption of the siberian trap flood basalts resulted in the heating and combustion of coals and organic rich sediments at the time of the permian mass extinction the presence of char in distant lake sediments linked to the eruption suggests that fly ash could have been generated by the coal combustion and then dispersed globally creating toxic marine conditions

increased soil gas radon and indoor radon concentrations in neoproterozoic olistostromes of the tepla barrandian unit czech republic the neoproterozoic olistostromes were first distinguished as a special geological unit in a generalised geological map of the czech republic on a scale 1 500 000 the olistostromes represent a tectonic melange or subaquatic continental slope slides formed by a mixture of black shales greywackes carbonates and shales forming an extremely inhomogeneous geological environment the extreme over limit values of indoor radon rn 222rn were first detected during check measurements performed for final building approval by team of the national radiation protection institute in a house situated on bedrock of black shales lithological component of olistostromes north eastward from plze additional measurements of soil gas rn performed by the czech geological survey were oriented to cover the whole olistostrome belt extending over 65 25 km area ne of plze prague general direction the increased concentrations both of soil gas and indoor rn were confirmed in the whole extent of neoproterozoic olistostrome belt compared to neighbouring geological units neoproterozoic metasediments on nw and cambrian palaeovolcanites and ordovician sediments on se this observation lead to increasing the radon index of olistostromes to medium radon category from the low one both in general and detailed rn index maps drawing the attention to this lithological type enables to improve the radon risk prevention for newly built houses and interest of remediation of existing houses not only in the specific area of the czech republic but also in other european countries where neoproterozoic olistostromes form the geological basement

pattern of marine mass extinction near the permian triassic boundary in south china the meishan section across the permian triassic boundary in south china is the most thoroughly investigated in the world a statistical analysis of the occurrences of 162 genera and 333 species confirms a sudden extinction event at 251 4 million years ago coincident with a dramatic depletion of 13ccarbonate and an increase in microspherules

factors controlling the emanation of radon and thoron in soils of the eastern u s a abstract emanation coefficients proportion of generated rn atoms that escape from a solid material have been measured for 222rn t 1 2 3 8 days and 220rn thoron t 1 2 55 s on 68 disaggregated soil samples from 12 soil profiles representative of the eastern u s a average values for sites are 0 20 for 222rn and 0 16 for 220rn based on distribution of 226ra among the exchangeable organic fe oxide sand silt and clay fractions of the soils a multiple regression indicates that the organic exchangeable fraction occurring mainly as coatings on grains has an emanation coefficient for 222rn of 0 46 and the silt clay fraction has an emanation coefficient of 0 22 the latter value is verified by experiments the organic component makes the largest single contribution to rn in soil gas mineral grains have twice the 222rn emanation as 220rn implying that about half the rn atoms are emanated directly to pore space and the remainder are freed by track etching and diffusion over a period of days emanation for 220rn appears to be dominated by fe oxides the main host for pedogenic 232th surface a and e horizons have low emanation coefficients for su220 rn probably because of a lack of fe oxides in these horizons

experimental study of radon production and transport in an analogue for the martian regolith abstract the suggestion that radon could be used as a radioactive tracer of regolith atmosphere exchanges and as a proxy for subsurface water on mars as well as its indirect detection in the martian atmosphere by the rover opportunity have raised the need for a better characterization of its production process and transport efficiency in the martian soil more specifically a proper estimation of radon exhalation rate on mars requires its emanation factor and diffusion length to be determined the dependence of the emanation factor as a function of pore water content at 267 and 293 k and the dependence of the adsorption coefficient on temperature specific surface area and nature of the carrier gas he he co 2 have been measured on a martian soil analogue hawaiian palagonitized volcanic ash jsc mars 1 whose radiometric analysis has been performed an estimation of radon diffusion lengths on mars is provided and is used to derive a global average emanation factor 2 6 5 that accounts for the exhalation rate inferred from the 210 po surface concentration detected on martian dust and from the 214 bi signal measured by the mars odyssey gamma ray spectrometer it is found to be much larger than emanation factors characterizing lunar samples but lower than the emanation factor of the palagonite samples obtained under dry conditions this result probably reflects different degrees of aqueous alteration and could indicate that the emanation factor is also affected by the current presence of pore water in the martian soil the rationale of the radon method as a technique to probe subsurface water on mars and its sensitivity to soil parameters are discussed these experimental data are useful to perform more detailed studies of radon transport in the martian atmosphere using global climate models and to interpret neutron and gamma data from mars odyssey gamma ray spectrometer

abrupt and gradual extinction among late permian land vertebrates in the karoo basin south africa the karoo basin of south africa exposes a succession of upper permian to lower triassic terrestrial strata containing abundant terrestrial vertebrate fossils paleomagnetic magnetostratigraphic and carbon isotope data allow sections to be correlated across the basin with this stratigraphy the vertebrate fossil data show a gradual extinction in the upper permian punctuated by an enhanced extinction pulse at the permian triassic boundary interval particularly among the dicynodont therapsids coinciding with negative carbon isotope anomalies

pre mass extinction decline of latest permian ammonoids the devastating end permian mass extinction is widely considered to have been caused by large scale and rapid greenhouse gas release by siberian magmatism although the proximate extinction mechanisms are disputed there is widespread agreement that a major extinction pulse occurred immediately below the biostratigraphically defined permian triassic boundary our statistical analyses of stratigraphic confidence intervals do not comply with a single end permian extinction pulse of ammonoids in iran high turnover rates and extinction pulses are observed over the last 700 k y of the permian period in two widely separated sections representative of a larger area analyses of body sizes and morphological complexity support a gradual decline over the same interval similar pre mass extinction declines and disturbances of the carbon cycle have sometimes been reported from other regions suggesting a widespread but often overlooked environmental deterioration at a global scale well before the traditional main extinction pulse

brachiopod miniaturization and its possible causes during the permian triassic crisis in deep water environments south china abstract brachiopod miniaturization is both the reduction in size of individuals of a species over time and where one brachiopod fauna dominated by larger individuals was replaced by a brachiopod fauna dominated by smaller individuals over time this paper investigates this phenomenon prior to and during the end permian crisis in a deep water setting in south china based on precise measurements of brachiopod body size and on the abundance and diversity of brachiopod species the process of miniaturization near the permian triassic boundary in deep water environments is characterized by 1 larger species including martinia sp costatumulus dongpanensis and anidanthus mucronata reduced in average body size and abundance over time towards the end permian brachiopod extinction event 2 small species including attenuatella mengi and spinomarginifera semicircridge showed a mixed response with either no size change or a reduction in average body size while these species increased in abundance over time indicating they were less sensitive to the stressed environmental setting 3 both the total abundance and the diversity of this brachiopod fauna decreased over time towards the end permian crisis regression an increased input of terrestrial material and productivity decline are considered to all have contributed to brachiopod miniaturization based on the biotic replacement and changes in sea water chemistry among these factors the fall in sea level is perhaps the primary factor and led to a decline in productivity and an increased input of terrestrial material into the marine setting

radon variations in an active landslide zone along the pindar river in chamoli district garhwal lesser himalaya india radon measurements were made in the soil and spring seepage water in and around an active landslide located along the pindar river in the chamoli district of uttaranchal in garhwal lesser himalaya to understand the application of radon in geological disasters the landslide is a compound slide i e a slump in the crown portion and debris slide and fall in the lower part the bedrock consists of gneisses and schists of the saryu formation of the almora group of precambrian age the presence of several small slump scars and debris slide fall scars along the length of the slide indicates continuous downward movement the radon concentrations in the present study are much lower in comparison to values reported from other regions however the present radon data show relative variation in the slide zone the concentration of radon measured in landslide zones varies from 3 1 bq l to 18 4 bq l in spring water and from 2 3 kbq m3 to 12 2 kbq m3 in the soil gas of the debris along the section of the slide the radon values in water and soil are slightly higher in the upper slopes i e toward the crown portion of the landslide as compared to the distal portion the relatively low concentration of radon both in soil gas and water in the toe portion of the landslide may be due to the high porosity of the debris which does not allow radon to accumulate in the soil and water whereas towards the crown portion the high frequency of fractures increases the surface area due to particle size reduction and the near absence of debris enhances the radon emanation in soil

significant wave height measured by coherent x band radar significant wave height is one of the most important parameters for characterizing ocean waves and essential for coastal protection shipping as well as off shore industry operations within this paper a robust method is introduced for retrieving significant wave heights from doppler speed measurements acquired with a coherent on receive marine radar the doppler velocity is caused by the surface scattering in the line of site of the radar to a huge extent its periodic component is induced by the orbital motions associated with surface waves the proposed methodology is based on linear wave theory accounts for projection effects caused by the fixed antenna look direction and was applied to a coherent on receive radar operating at x band with vertical polarization in transmit and receive to show the overall performance of the method a data set consisting of approximately 100 days of radar measurements was analyzed and used to retrieve significant wave heights comparisons to wave measurements collected by a wave rider buoy resulted in a root mean square rms error of 0 21 m and a bias of 0 m without any calibration parameters needed to further improve the accuracy of significant wave height a calibration factor needs to be accounted for which improves the rms error to 0 15 m with a negligible bias of 0 01 m

importance of atmospheric inputs and fe oxides in controlling soil uranium budgets and behavior along a hawaiian chronosequence abstract a long term budget of uranium calculated for a chronosequence of hawaiian soils demonstrates the importance of mineral aerosol deposition as a geochemical pathway a series of sequential extractions on the same soils shows a strong association between fe oxides and uranium especially the amorphous and poorly crystalline fe oxides present in intermediate age soils 20 and 150 ka despite intense leaching conditions soil u contents were found to increase between 20 fold and 60 fold with age along the chronosequence from 9 to 17 g cm 2 at 0 3 ka sites to 344 543 g cm 2 at the 4100 ka site an open system transport function comparing u to an index least mobile element nb was used to calculate u gains or losses from the soils relative to the input from parent material weathering results show small losses or small gains 25 of u occurred in soils 150 ka and younger while gains of up to 531 u occurred in soils older than 150 ka highlighting the importance of mineral aerosol dust deposition at the older sites in the 4100 ka soil the ratio of dust derived u inputs to parent material derived u inputs is approximately 6 sequential extractions show that between 0 1 and 1 2 of the total u in the soils was extracted with ammonium acetate indicating that very little u exists as exchangeable cations a second extraction employing citrate dithionate and hydroxylamine hydrochloride was performed to extract u associated with fe oxides average percent occurrences for u in the fe oxide extraction for each profile are 7 at 0 3 ka 53 at 20 ka 40 at 150 ka and 17 at 4100 ka illustrating an increase with age to 20 ka followed by a subsequent decline this parallels the trend observed in amorphous fe oxide content suggesting that adsorption on amorphous fe oxides is the dominant control on u in the intermediate age soils

an analogue validation study of natural radionuclide migration in crystalline rocks using uranium series disequilibrium studies abstract concentrations and isotope ratios of natural decay series radionuclides have been studied in three contrasting crystalline rock drillcore sections intersecting water conducting fractures deep in the bedrock radioactive disequilibria resulting from rock water interactions were observed in two of the cores these indicated u migration along distances of 40 cm or more on a time scale of 1 myr in conjunction with th immobility under the same conditions fracture surface minerals showed a high affinity for radionuclide retardation and a limit of 3 cm is suggested for the migration of radionuclides from fracture fluids into the saturated rock this limit may correspond to enhanced matrix porosities resulting from earlier hydrothermal activity along the same channels

distribution probability of large scale landslides in central nepal abstract large scale landslides in the himalaya are defined as huge deep seated landslide masses that occurred in the geological past they are widely distributed in the nepal himalaya the steep topography and high local relief provide high potential for such failures whereas the dynamic geology and adverse climatic conditions play a key role in the occurrence and reactivation of such landslides the major geoscientific problems related with such large scale landslides are 1 difficulties in their identification and delineation 2 sources of small scale failures and 3 reactivation only a few scientific publications have been published concerning large scale landslides in nepal in this context the identification and quantification of large scale landslides and their potential distribution are crucial therefore this study explores the distribution of large scale landslides in the lesser himalaya it provides simple guidelines to identify large scale landslides based on their typical characteristics and using a 3d schematic diagram based on the spatial distribution of landslides geomorphological geological parameters and logistic regression an equation of large scale landslide distribution is also derived the equation is validated by applying it to another area for the new area the area under the receiver operating curve of the landslide distribution probability in the new area is 0 699 and a distribution probability value could explain 65 of existing landslides therefore the regression equation can be applied to areas of the lesser himalaya of central nepal with similar geological and geomorphological conditions

two pulses of extinction during the permian triassic crisis over 90 of marine species were lost during the end permian extinction fossil data show that the crisis in china was marked by two distinct phases of marine extinction separated by a 180 000 year recovery period

radon emanation coefficients of several minerals how they vary with physical and mineralogical properties the escape rates of radon gas from rocks and minerals are of great relevance to many branches of geosciences and it is thus important to understand the physical and mineralogical properties that control radon emanation rates mechanisms of radon loss from minerals have direct bearing on the reliability of u pb and u th he geochronology fourteen minerals from three different mineral groups and with localities spanning three continents were selected for this study the radon emanation coefficients rec for each mineral were measured as a function of grain size temperature 238 u and 232 th activities total absorbed dose density and mineral melting temperature the measured 238 u and 232 th activities ranged from 0 01 to 6487 bq g and from below detection limit to 776 bq g respectively the rec values for unheated pulverized samples ranged from 0 083 to 7 0 which is comparable to previously reported ranges except for zircon an inverse correlation between grain size and rec was observed full annealing of fission tracks resulted in an overall decrease in rec values suggesting that nuclear tracks could possibly act as conduits for radon release while activity dose density and melting temperatures are not strongly correlated with rec values it was observed that minerals with high melting points 1400 c have lower rec values most likely due to inhibition of radon release by compact crystal lattice structures this is the first attempt to our knowledge to correlate rec values with melting temperature and this study reports six minerals for which no rec values have been previously reported

uranium and microcracks in a 1 000 meter core redstone new hampshire the spatial distribution and mineralogical association of uranium in 30 samples of a 1 000 meter core from the redstone nh quarry were examined with fission track techniques backscattered electron imaging and energy dispersive x ray spectrometry with the following results for the conway and mount osceola granites 1 uranium occurs in microcracks sealed with siderite and or with ca re fluorocarbonate minerals the uranium contents of siderite and the re fluorocarbonates are 1 to 30 ppm and 500 1 500 ppm respectively 2 siderite and to a lesser extent re fluorocarbonate minerals occur as replacement minerals of amphibole and biotite the re fluorocarbonates are the main alteration minerals of allanite 3 the degree of alteration and the extent of uranium redistribution are greater in samples with major uraniferous microcracks 4 the contents of ca and mn are approximately constant for siderite in sealed cracks throughout the conway and mount osceola granites for the entire section penetrated by the corehole approximately 700 meters from these observations we conclude that an extensive set of fractures throughout a significant volume of the mount osceola and conway granties were the conduits through which hydrothermal fluids containing co2 uranium and res circulated microcracks facilitated fluid rock interactions resulting in alteration and uranium redistribution certain primary uraniferous accessory minerals i e allanite and ilmenorutile may have been the source for at least part of the uranium and res that now occur in secondary minerals in these granites

radon emanation of heterogeneous basin deposits in kathmandu valley nepal abstract effective radium 226 concentration ecra has been measured in soil samples from seven horizontal and vertical profiles of terrace scarps in the northern part of kathmandu valley nepal the samples belong to the thimi gokarna and tokha formations dated from 50 to 14 ky bp and represent a diverse fluvio deltaic sedimentary facies mainly consisting of gravelly to coarse sands black orange and brown clays ecra was measured in the laboratory by radon 222 emanation the samples n 177 are placed in air tight glass containers from which after an accumulation time varying from 3 to 18 days the concentration of radon 222 radioactive decay product of radium 226 and radioactive gas with a half life of 3 8 days is measured using scintillation flasks the ecra values from the seven different profiles of the terrace deposits vary from 0 4 to 43 bq kg 1 with profile averages ranging from 12 1 to 27 2 bq kg 1 the values have a remarkable consistency along a particular horizon of sediment layers clearly demonstrating that these values can be used for long distance correlations of the sediment horizons widely separated sediment profiles representing similar stratigraphic positions exhibit consistent ecra values in corresponding stratigraphic sediment layers ecra measurements therefore appear particularly useful for lithologic and stratigraphic discriminations for comparison ecra values of soils from different localities having various sources of origin were also obtained 9 2 0 4 bq kg 1 in soils of syabru bensi central nepal 23 1 bq kg 1 in red residual soils of the bhattar trisuli bazar terrace north of kathmandu 17 1 0 3 bq kg 1 in red residual soils of terrace of kalikasthan north of trisuli bazar and 10 1 bq kg 1 in red residual soils of a site near nagarkot east of kathmandu the knowledge of ecra values for these various soils is important for modelling radon exhalation at the ground surface in particular in the vicinity of active faults importantly the study also reveals that above numerous sediments of kathmandu valley radon concentration in dwellings can potentially exceed the level of 300 bq m 3 for residential areas a fact that should be seriously taken into account by the governmental and non governmental agencies as well as building authorities

permian triassic extinction pattern revealed by foraminifers and geochemical records in the central persian gulf southern iran abstract permian triassic boundary ptb foraminifers are studied from the upper part of the dalan formation and the base of the kangan formation in four wells a b e f on and near the qatar arc persian gulf iran isotope studies including 13c and 18o values from wells b and e and 87sr 86sr ratios in wells b e and f have also been carried out to possibly provide a high resolution extinction pattern of foraminifers in the ptb interval the latter has been thoroughly investigated in iran turkey south china vietnam slovenia carnic alps and bukk mountains kashmir greenland and serbia the distribution of the last appearance of foraminiferal genera from the ptb interval in all of the wells is very similar featuring a stepwise extinction from 3 to 2 m before the boundary and compares to that observed in some of the sections from elsewhere i e south china vietnam slovenia and serbia the 13c value in wells b and e shows a negative shift at the base of a thrombolite unit immediately after the considered ptb and another negative shift at about 11 m below it in well e the thrombolite unit is assumed as earliest triassic but questionable with no supportive conodonts the 18o isotope values in wells b and e demonstrate the same negative upward trend due to dysoxic or anoxic conditions in the end permian oceans the uniform reduction without any sharp incline in the 18o profile suggests concurrent global warming the highest 87sr 86sr ratio fluctuations in wells b e and f coincide with the appearance of thrombolites changes in the profiles of carbon oxygen and strontium isotopes close to the ptb in wells b e and f seem to correspond to lithofacies variations from limestone to dolostone and a reduction in foraminiferal diversity these changes substantiate a clear perturbation in the marine environmental and global geochemistry elements through the ptb interval the 13c 18o and 87sr 86sr values obtained from the studied wells are comparable to those in other ptb stratigraphic sections in the paleo tethyan region

the transport of u and th series nuclides in sandy confined aquifers a comprehensive evaluation of the transport of u th ra and rn nuclides of the 238 u and 232 th decay series in an unconfined sandy aquifer long island ny was conducted groundwater data are compared with results of a theoretical transport model of weathering of aquifer grains and interaction with surface coatings to establish relationships between the concentrations of the radionuclide activities in the water and flow line distance the data provide estimates for geochemical parameters including weathering rates and chemical reactivities in both the vadose zone and the aquifer a theoretical treatment of the transport is presented that considers the reaction between the water and a reactive surface layer it is found that a model with chemical exchange between the surface layer and the water for all species is not valid and that the effects of saturation and irreversible precipitation of th is required the water table shows a relatively wide range in u activities the only element in the u th series for which vadose zone input is significant in the aquifer high weathering of u and recoil inputs of 234 u to the water occur in the upper 3 m of the vadose zone while lower weathering and removal of u from the water occur below the deeper aquifer has variable 238 u activities that can be accounted for by input from the vadose zone and is not a result of non conservative behavior the isotopic composition of u is shown to be directly related to the recoil rate relative to the weathering rate the wide range of 238 u in the aquifer waters is a reflection of diverse vadose zone inputs showing that dispersive mixing is not a dominant effect the higher values of 234 u in the aquifer reflect the recoil weathering input ratios from within the aquifer where the weathering rate is lower than the vadose zone both high u activities and high 234 u values cannot be obtained in the vadose zone or within reasonable flow distances in the aquifer radium isotopes are found to be in exchange equilibrium with the surface layer 224 ra 228 ra and 226 ra have comparable activities throughout the aquifer in the vadose zone the dominant input of ra to groundwater is weathering and recoil as found elsewhere the 222 rn in the water is a large fraction 5 of the rn produced in the aquifer rock this cannot be due to ra precipitation onto surface coatings in the aquifer as supported by present weathering with th in exchange equilibrium with the surface layer it is found that th is saturated in the waters under oxidizing conditions so that the weathering input is irreversibly precipitating onto surfaces however it is shown that under somewhat reducing conditions th activities are much higher and the th u ratio in the solution is approximately that of the rock we propose that under oxidizing conditions the source of rn is a surface coating enriched in 232 th and 230 th this th was precipitated in an earlier phase during rapid dissolution of readily weathered phases that contain 10 of the u th inventory of the rock with the associated u carried away in solution therefore the previously precipitated 230 th and 232 th produce daughter nuclides in the surface coating which are the dominant contributors of ra and rn to the ground water in particular rn is provided by very efficient losses by diffusion or recoil from the surface coating this then does not require recent large recoil losses from the parent rock or the presence of nanopores in the rock the first data of both long lived 232 th and short lived 234 th and 228 th in ground water is reported the th isotope activities indicate that desorption kinetics are slow and provide the first estimate based on field data of the th desorption rate from an aquifer surface the mean residence time of th in the surface coating is 3000 y while in the water it is 1 h ra is in partition equilibrium with the aquifer surface layer however the strong fixation of th on surface coatings is very susceptible to changes in oxidation state as is shown by a comparison of two adjacent aquifers this makes it difficult to define with certainty the retentive characteristics in natural systems in general it is shown that the distributions of naturally occurring nuclides can be used to calculate values for transport parameters that are applicable to the transport of anthropogenic nuclides

radon emanation from giant landslides of koefels tyrol austria and langtang himal nepal the identification of extremely high indoor radon concentrations in the village umhausen tyrol austria initiated a scientific program to get information about the source and distribution of this noble gas the high concentrations can not be related to u anomalies or large scale fault zones the nearby giant landslide of koefels with its highly fractured and crushed orthogneisses are the only possible source of radon despite the fact that the u and ra content of the rocks is by no means exceptional the reasons for the high emanation rates from the landslide are discussed and compared to results gained from a similar examination of the giant landslide of langtang himal nepal the exceptional geologic situation in both cases as well as the spatial distribution of different concentration levels indicate that both landslides must be considered as the production sites of radon independent of the u and ra contents of the rocks the most important factors producing high emanation rates are the production of a high active surface area and circulation pathways for rn enriched soil air by brittle deformation due to the impact of the landslidemass

microscopic lamellar deformation features in quartz discriminative characteristics of shock generated varieties the appearance and orientation of microscopic lamellar deformation features in quartz have been examined in samples from different geologic environments lamellar deformation features from known shock and or impact environments are sharp parallel closely spaced and tend to extend in a continuous manner across entire grains they have specific well documented orientations and occur in multiple sets per grain lamellar deformation features from other geologic environments including tectonic and explosive volcanic only superficially resemble shock features they are generally less well defined slightly curved wider spaced and tend to extend in a discontinuous manner across parts of grains they have relatively random orientations only some of which correspond to known shock orientations and generally occur as single sets per grain on the basis of these observations we conclude that there is a characteristic set of microscopic deformation features produced in quartz by shock these so called planar features differ from microscopic lamellar deformation features produced by other dynamic processes therefore the case for the formation of characteristic planar features in quartz by natural processes other than impact is still not proven