imaging and modeling the ionospheric airglow response over hawaii to the tsunami generated by the tohoku earthquake of 11 march 2011 1 although only centimeters in amplitude over the open ocean tsunamis can generate appreciable wave amplitudes in the upper atmosphere including the naturally occurring chemiluminescent airglow layers due to the exponential decrease in density with altitude here we present the first observation of the airglow tsunami signature resulting from the 11 march 2011 tohoku earthquake off the eastern coast of japan these images are taken using a wide angle camera system located at the top of the haleakala volcano on maui hawaii they are correlated with gps measurements of the total electron content from hawaii gps stations and the jason 1 satellite we find waves propagating in the airglow layer from the direction of the earthquake epicenter with a velocity that matches that of the ocean tsunami the first ionospheric signature precedes the modeled ocean tsunami generated by the main shock by approximately one hour these results demonstrate the utility of monitoring the earth s airglow layers for tsunami detection and early warning

novel paleoecology of a postextinction reef famennian late devonian of the canning basin northwestern australia reefs are widely supposed to be particularly susceptible to mass extinction events and to survive only as low diversity remnant communities dominated by holdover or disaster taxa famennian late devonian reefs exposed in the windjana limestone of the canning basin northwestern australia demonstrate however that a novel reef ecology was established in the immediate aftermath of the frasnian famennian mass extinction here diverse calcimicrobes including rothpletzella spp shuguria spp ortonella and girvanella together with bryozoans brachiopods and stromatoporoid sphinctozoan and lithistid sponges grew as complex framework intergrowths in previously undocumented morphological forms forming spectacular elevated laminar to platy structures to 3 m in diameter and 0 35 m thick at least 15 morphospecies of lithistids are now identified where only two were previously documented these communities show no substantial reduction in biodiversity compared to frasnian counterparts nor any change in tiering or loss of complex ecological interactions these observations suggest that where stable carbonate platforms persisted after mass extinction events reef building could continue more important they demonstrate that no protracted interval of time was necessarily required either for recovery to ecological stability or for completely new reef ecologies to assemble such studies highlight the need to document ecosystem recovery after mass extinction events using detailed paleoecological analyses in addition to simple compilations of global biodiversity changes

assessment of heavy metals concentrations with emphasis on arsenic in the tabriz plain aquifers iran the tabriz area is one of the most industrialized areas in northwest of iran the heavy industrialization and the increasing urbanization are responsible for the rapidly increasing stress on the groundwater of the area the objective of this study was to evaluate heavy metals such as fe mn al zn as and cr in groundwater and their spatial distribution in tabriz plain aquifer the concentrations of fe cr mn as and al in some of the groundwater samples exceed the maximum admissible concentration mac correlation matrix cm and principal components analysis pca methods were employed to identify source apportionment of contamination parameters in groundwater there are two types of aquifers with different quality of water in the plain an unconfined aquifer with saline water and a confined aquifer with fresh water quality arsenic concentrations in the unconfined aquifer and in the recharge areas of the plain boundary are low with an average of 25 8 g l while in the confined aquifer and deep wells the concentrations are high with an average of 122 5 g l the arsenic occurring in groundwater resources of the area originates from geological formations such as alluvial tuffs of sahand mountain and its concentration is highly dependent on hydrogeological and environmental reducing conditions residence time of water and depth of the sampling wells

peculiar features of the low latitude and midlatitude ionospheric response to the st patrick s day geomagnetic storm of 17 march 2015 the current study aims at investigating and identifying the ionospheric effects of the geomagnetic storm that occurred during 17 19 march 2015 incidentally with sym h hitting a minimum of 232 nt this was the strongest storm of the current solar cycle 24 the study investigates how the storm has affected the equatorial low latitude and midlatitude ionosphere in the american and the european sectors using available ground based ionosonde and gps tec total electron content data the possible effects of prompt electric field penetration is observed in both sectors during the main phase of the storm in the american sector the coexistence of both positive and negative ionospheric storm phases are observed at low latitudes and midlatitudes to high latitudes respectively the positive storm phase is mainly due to the prompt penetration electric fields the negative storm phase in the midlatitude region is a combined effect of disturbance dynamo electric fields the equatorward shift of the midlatitude density trough and the equatorward compression of the plasmapause in combination with chemical compositional changes strong negative ionospheric storm phase is observed in both ionosonde and tec observations during the recovery phase which also shows a strong hemispherical asymmetry additionally the variation of equatorial ionization anomaly as seen through the swarm constellation plasma measurements across different longitudes has been discussed we also take a look at the performance of the iri real time assimilative mapping during this storm as an ionospheric space weather tool

stereo and wind observations of a fast icme flank triggering a prolonged geomagnetic storm on 5 7 april 2010 1 on 5 april 2010 an interplanetary ip shock was detected by the wind spacecraft ahead of earth followed by a fast average speed 650 km s ip coronal mass ejection icme during the subsequent moderate geomagnetic storm minimum dst 72 nt maximum kp 8 communication with the galaxy 15 satellite was lost we link images from stereo secchi to the near earth in situ observations and show that the icme did not decelerate much between sun and earth the icme flank was responsible for a long storm growth phase this type of glancing collision was for the first time directly observed with the stereo heliospheric imagers the magnetic cloud mc inside the icme cannot be modeled with approaches assuming an invariant direction these observations confirm the hypotheses that parts of icmes classified as 1 long duration mcs or 2 magnetic cloud like mcl structures can be a consequence of a spacecraft trajectory through the icme flank

chromium vi generation in vadose zone soils and alluvial sediments of the southwestern sacramento valley california a potential source of geogenic cr vi to groundwater abstract concentrations of geogenic cr vi in groundwater that exceed the world health organization s maximum contaminant level for drinking water 50 g l 1 occur in several locations globally the major mechanism for mobilization of this cr vi at these sites is the weathering of cr iii from ultramafic rocks and its subsequent oxidation on mn oxides this process may be occurring in the southern sacramento valley of california where cr vi concentrations in groundwater can approach or exceed 50 g l 1 to characterize cr geochemistry in the area samples from several soil auger cores approximately 4 m deep and drill cores approximately 25 m deep were analyzed for total concentrations of 44 major minor and trace elements cr associated with labile mn and fe oxides and cr vi total concentrations of cr in these samples ranged from 140 to 2220 mg per kg soil between 9 and 70 mg per kg soil was released by selective extractions that target fe oxides but essentially no cr was associated with the abundant reactive mn oxides up to 1000 mg hydroxylamine reducible mn per kg soil was present both borehole magnetic susceptibility surveys performed at some of the drill core sites and relative differences between cr released in a 4 acid digestion versus total cr lithium metaborate fusion digestion suggest that the majority of total cr in the samples is present in refractory chromite minerals transported from ultramafic exposures in the coast range mountains chromium vi in the samples studied ranged from 0 to 42 g kg 1 representing a minute fraction of total cr chromium vi content was typically below detection in surface soils top 10 cm where soil organic matter was high and increased with increasing depth in the soil auger cores as organic matter decreased maximum concentrations of cr vi were up to 3 times greater in the deeper drill core samples than the shallow auger cores although cr vi in these vadose zone soils and sediments was only a very small fraction of the total solid phase cr they are a potentially important source for cr vi to groundwater enhanced groundwater recharge through the vadose zone due to irrigation could carry cr vi from the vadose zone to the groundwater and may be the mechanism responsible for the correlation observed between elevated cr vi and no 3 concentrations in previously published data for valley groundwaters incubation of a valley subsoil showed a cr vi production rate of 24 g kg 1 a 1 suggesting that field cr vi concentrations could be regenerated annually increased cr vi production rates in h amended soil incubations indicate that soil acidification processes such as nitrification of ammonium in fertilizers could potentially increase the occurrence of geogenic cr vi in groundwater thus despite the natural origin of the cr cr vi generation in the sacramento valley soils and sediments has the potential to be influenced by human activities

environmental record of devonian mississippian carbonate and low oxygen facies transitions southernmost canadian rocky mountains and northwesternmost montana uppermost devonian and lower mississippian strata in the southernmost canadian rocky mountains and adjacent montana record part of a widespread low oxygen episode in middle paleozoic epicontinental and shelf seas and provide critical information concerning the oceanographic setting of the western continental margin of euramerica at this time during early middle famennian time the region was the site of a westward deepening carbonate ramp palliser formation that was bordered to the west by a shale basin lussier region sedimentation patterns changed in middle late famennian time with the termination of carbonate ramp sedimentation and ultimate deposition of organicrich sediments in an oxygen stressed deep water setting exshaw formation a model for the widespread deposition of these sediments entails the initial flooding of epicontinental shelf seas with water derived from an expanded and intensified oxygen minimum zone during a late famennian transgression sedimentation of anaerobic to marginally aerobic deep water lower banff facies occurred into middle tournaisian and locally late tournaisian time prior to the westward progradation of carbonate ramp sediments of the middle and upper banff quartzofeld spathic clastic rocks in the exshaw and banff reflect the periodic influx of detritus from a likely western antler age orogenic source from late famennian into late tournaisian time degree of bottom water oxygenation during deposition of the exshaw and banff low oxygen facies was recognized using ichno fabric organic c and s relationships and degree of pyritization dop anaerobic laminated black shales with high dop values lack a macrobenthos with the notable exception of rare concentrations of inarticulate brachiopods on bedding planes dysaerobic to marginally aerobic facies have intermediate dop values and a gradient of increasing degree of bioturbation

effects of st patrick s day geomagnetic storm of march 2015 and of june 2015 on low equatorial d region ionosphere d region effects of the 17 19 march 2015 a st patrick s day super geomagnetic storm dst 223 nt using a navigational transmitter very low frequency vlf signal nwc 19 8 khz recorded at a low latitude indian station allahabad geomag lat 16 45 n have been analyzed and compared with similar strength of the 22 25 june 2015 storm dst 204 nt during the march storm nwc signal amplitude decreased on 17 march main phase of the storm and recovered on 27 march which is 1 day after the recovery of the storm whereas for the june storm vlf amplitude decreased for 2 days only during its recovery phase the decrease in the amplitude was pronounced during evening terminator for both the storms the modeling of vlf signal anomaly on 17 march and on 25 june using long wave propagation capability code shows an increase in the d region reference height h by 2 6 km and 2 5 km for march and june storms respectively the d region electron density ne determined using storm time h and sharpness factor shows a decrease in the ne during the main phase followed by a slow recovery during the recovery phase of the march storm whereas june 2015 storm showed a decrease in the ne only on 25 and 26 june morlet wavelet analysis of the amplitude for both the storms shows a presence of strong wave like signatures suggesting propagation of atmospheric gravity waves traveling ionosphere disturbances to the low latitude d region due to the joule heating at high latitudes

silicon and chromium stable isotopic systematics during basalt weathering and lateritisation a comparison of variably weathered basalt profiles in the deccan traps india global biomass production is fundamentally affected by the hydrological cycling of elements at the earth s surface continental weathering processes are the major source for most bio essential elements in marine environments and therefore affect primary productivity in addition critical zone biomass depends on energy and chemical exchange reactions in weathering profiles the latter reservoirs are in turn influenced by different climatic conditions that control weathering and pore water parameters like ph and eh which regulate mineral break down rates and dictate the mobility and mass flux of elements two deccan traps basalt weathering profiles of contrasting age and alteration intensity provide a natural laboratory for investigating the effects of rock alteration on si and cr and their isotopic systematics the quaternary chhindwara profile has progressed to a moderate degree of alteration saprolite while the paleogene bidar example displays an extremely altered laterite the chhindwara saprolite profile shows a near uniform cr and si concentration and isotopic composition whereas the bidar laterite profile is characterised by an intense loss of si a large enrichment of cr within the most altered uppermost levels and a wide range of cr stable isotope ratios 0 85 to 0 36 parts per thousand delta cr 53 52 a co variation between si and cr isotopes as well as their co variation with iron content provides empirical evidence that iron redistribution within the profile has a large effect on cr mobility and si isotopic fractionation therefore it is concluded that iron oxides exert a primary control over the isotopic composition of both cr and si in pore waters of laterites since laterite formation is promoted by tropical climates the results of this study provide new evidence to suggest that the hydrological cr and si fluxes originating from continental weathering have changed in accordance with large scale deep time climate variation and continental plate configuration an increased flux of si and greater magnitude of cr mobility and isotopic fractionation are possibly amplified under co2 rich greenhouse episodes and or when large landmasses were tectonically arranged at near equatorial latitudes

the multi instrumented studies of equatorial thermosphere aeronomy scintillation system climatology of zonal drifts a spaced antenna scintillation system was installed at ancon peru in may 1994 to measure scintillation of 250 mhz signals from a geostationary satellite by three antennas spaced in the magnetic east west direction these measurements were used to establish the climatology of the zonal drift of the irregularities which cause equatorial scintillations the major objective of this study is to compare this drift climatology to the climatology of zonal neutral wind which is the driver of the equatorial electrodynamics a comparison of these two climatologies in conjunction with scintillation statistics may provide some clues regarding factors which help or hinder the formation of equatorial spread f esf with these objectives in mind the first year s drift and scintillation statistics have been presented as a function of local time season and magnetic activity and compared with the statistics of ion drift published earlier from incoherent scatter radar observations the scintillation drift is in good agreement with the jicamarca radar observations except for the fact that the local time dependence of our drift observations exhibit a broader maximum the broad maximum may be attributed to lower ion drag experienced in the presence of esf due to sustained uplifting of the ionosphere during magnetically active periods the scintillation drift often exhibits east to west reversals presumably because of the disturbance dynamo effects the westward drifts during such reversals may be as large as 100 m s we have also modeled the zonal drifts as a seasonal basis by using hedin s neutral wind model and anderson s fully analytical ionospheric model the modeled zonal drifts present good quantitative agreement with the drifts obtained with the scintillation technique

paleokarst in an upper devonian reef complex of the canning basin western australia abstract evidence for subaerial exposure of an early famennian platform is recorded within the fore reef slope succession in the napier range reef complex of the northern canning basin this observation supports recent sequence stratigraphic interpretations of fluctuations in relative sea level throughout reef evolution in this basin and contrasts with previous outcrop based interpretations that there were no sea level falls except at the frasnian famennian boundary remnants of the paleokarst surface are preserved in allochthonous reef flat blocks that are temporally and spatially related to lenticular siliciclastic units subaerial exposure of the platform margin during a third order sea level fall in the early famennian led to the formation of karst cavities on the reef flat and collapse of parts of the reef margin during this time siliciclastic sands were fed to the slope where they were deposited as a series of aprons along the margin in the early stages of the ensuing transgression renewed marine conditions enabled cyanobacteria to colonize the cavities as sea level continued to rise siliciclastic sands were reworked across the platform filling the encrusted cavities the reef flat blocks were dislodged during the late transgression n response to instability that may have been caused by triggers such as rising pore fluid pressures and or tectonic activity they were emplaced on the siliciclastic slope aprons towards the end of sand deposition as sea level on the platform continued to rise and carbonate production resumed

the depositional record of the frasnian famennian boundary interval in a fore reef succession canning basin western australia abstract the effects of the global frasnian famennian f f biotic crisis on the shallow marine reef builders and associated biota in a laterally extensive late frasnian reef complex on the lennard shelf northern canning basin are recorded in the well exposed fore reef succession napier formation of the napier range the conodont defined f f boundary lies within a distinctive and mappable stratigraphic interval up to 15 m thick which separates highly fossiliferous frasnian from markedly less fossiliferous famennian carbonate and siliciclastic lithofacies marked lateral facies variation within the interval means that the actual boundary is not represented by a discrete bed or surface the interval is characterised by a range of lithofacies that record very low sedimentation rates on the slope and reworking and bioturbation of slope strata indicating a condensed interval with negligible sediment input from contemporaneous carbonate platform production siliciclastic lithofacies and abundant sponge debris are locally developed macrofossil content is generally very low but there is no evidence for anoxic or hypoxic conditions during deposition at a range of palaeowater depths allochthonous blocks of stromatoporoid bearing limestone are absent from the uppermost frasnian fore reef strata and stromatoporoid debris is significantly reduced prior to the end of the frasnian this suggests that extinction of the stromatoporoid reef margins occurred before the f f boundary with microbial communities dominating the platform margins prior to the famennian sedimentological and biostratigraphic evidence suggests that a series of sea level fluctuations in response to basin tectonism generated recurring or ongoing environmental stress in the stromatoporoid dominated reefal communities because of recurring reductions in living space influxes of siliciclastic sediment supply from the proximal highlands and quite possibly generation of toxic too saline or too nutrient rich lagoonal water these conditions were potentially superimposed on a global regime of incipient cooling climate leading to widespread glaciation in the late carboniferous

diagenesis of devonian reefal carbonates in the oscar range canning basin western australia abstract the oscar range part of the extensive devonian reef complex of the northern canning basin is a large atoll 80 10 km in which frasnian and famennian late devonian reefs grew around an emergent island of precambrian metasedimentary rocks many sediments in the oscar range had high depositional porosities but this porosity was largely occluded by diagenetic alteration diagenesis included marine cementation dolomitization pressure solution burial cementation and karstification field mapping petrography cathodoluminescence and carbon and oxygen isotope analyses have been used to document six major diagenetic episodes that affected oscar range sediments earliest cementation occurred in the marine environment where reef margin and associated subfacies developed abundant non luminescing radiaxial fibrous and microcrystalline calcite cements based on convergent covariant isotopic trends marine cements had a characteristic late devonian oxygen signature of 4 5 0 5 pdb and a carbon signature of 2 0 0 5 pdb in well cemented parts of the reef complex synsedimentary neptunian fissures formed and were filled with cement and sediment cements in these fissures have isotopic ratios that are essentially identical to the values determined for marine cements thereby suggesting that the fissures acted as conduits f r seawater flow and cementation early in the history of the reef complexes marine diagenesis was followed by marine burial and possible meteoric phreatic cementation and dolomitization marine cements are overgrown by non luminescing scalenohedral cements that grade into banded bright and non luminescing blocky calcite cements that are common on the platform but are missing in many reef margin and marginal slope deposits banded luminescence may represent fluctuating reducing and oxidizing conditions in pore waters across the intermittently emergent platform the reef complexes however were generally drowned reefs with little chance for prolonged meteoric exposure this sedimentologic evidence suggests that banded luminescing cements may have formed in the marine burial environment the next cement generation consists of non luminescing non ferroan bloc y calcites that occur throughout the reef complex stratigraphic relationships combined with isotopic results 18o 6 0 to 9 0 13c 2 0 suggest that this spar is a burial cement resulting from late devonian through early carboniferous burial the reef complex was exhumed and eroded in the late carboniferous dedolomite dolo moldic porosity pisolitic calcrete crusts iron oxide stained blocky cements and deep 200 m sinkholes formed at the unconformity surface non ferroan irregularly banded moderate to bright luminescing blocky calcite precipitated throughout the reef complex unconformity related cements calcrete crusts and dedolomites have distinctive isotopic signatures that show little variation in oxygen 7 0 to 9 0 but have a broad range of carbon values 1 5 to 8 0 highly negative carbon values are probably related to the interaction of meteoric fluids with isotopically light soil gas at the er sion surface in post carboniferous time most of the remaining porosity was filled with non ferroan bright luminescing blocky calcite that formed by pressure solution reprecipitation during burial isotopic analyses 18o 8 0 to 12 0 13c 1 5 support a burial origin for this generation of cements these cements fill primary porosity tension gashes along stylolites and hairline fractures along which hematite is leached a final generation of ferroan homogeneous dull to non luminescing blocky calcite cement formed in a late burial event that according to isotopic evidence 18o 10 5 to 15 0 13c 2 0 to 9 0 was probably related to movement of basinal brines through the reef complexes

empirical models of storm time equatorial zonal electric fields ionospheric plasma drifts often show highly complex and variable signatures during geomagnetically active periods due to the effects of different disturbance processes we describe initially a methodology for the study of storm time dependent ionospheric electric fields we present empirical models of equatorial disturbance zonal electric fields obtained using extensive f region vertical plasma drift measurements from the jicamarca observatory and auroral electrojet indices these models determine the plasma drift perturbations due to the combined effects of short lived prompt penetration and longer lasting disturbance dynamo electric fields we show that the prompt penetration drifts obtained from a high time resolution empirical model are in excellent agreement with results from the rice convection model for comparable changes in the polar cap potential drop we also present several case studies comparing observations with results obtained by adding model disturbance drifts and season and solar cycle dependent average quiet time drift patterns when the disturbance drifts are largely due to changes in magnetospheric convection and to disturbance dynamo effects the measured and modeled drift velocities are generally in good agreement however our results indicate that the equatorial disturbance electric field pattern can be strongly affected by variations in the shielding efficiency and in the high latitude potential and energy deposition patterns which are not accounted for in the model these case studies and earlier results also suggest the possible importance of additional sources of plasmaspheric disturbance electric fields

a regional scale study of chromium and nickel in soils of northern california usa abstract a soil geochemical survey was conducted in a 27 000 km 2 study area of northern california that includes the sierra nevada mountains the sacramento valley and the northern coast range the results show that soil geochemistry in the sacramento valley is controlled primarily by the transport and weathering of parent material from the coast range to the west and the sierra nevada to the east chemically and mineralogically distinctive ultramafic um rocks e g serpentinite outcrop extensively in the coast range and sierra nevada these rocks and the soils derived from them have elevated concentrations of cr and ni surface soil samples derived from um rocks of the sierra nevada and coast range contain 1700 10 000 mg kg cr and 1300 3900 mg kg ni valley soils west of the sacramento river contain 80 1420 mg kg cr and 65 224 mg kg ni reflecting significant contributions from um sources in the coast range valley soils on the east side contain 30 370 mg kg cr and 16 110 mg kg ni lower cr and ni concentrations on the east side of the valley are the result of greater dilution by granitic sources of the sierra nevada chromium occurs naturally in the cr iii and cr vi oxidation states trivalent cr is a non toxic micronutrient but cr vi is a highly soluble toxin and carcinogen x ray diffraction and scanning electron microscopy of soils with an um parent show cr primarily occurs within chromite and other mixed composition spinels al mg fe cr chromite contains cr iii and is highly refractory with respect to weathering comparison of a 4 acid digestion hno 3 hcl hf hclo 4 which only partially dissolves chromite and total digestion by lithium metaborate libo 3 fusion indicates a lower proportion of chromite bound cr in valley soils relative to um source soils groundwater on the west side of the sacramento valley has particularly high concentrations of dissolved cr ranging up to 50 g l 1 and averaging 16 4 g l 1 this suggests redistribution of cr during weathering and oxidation of cr iii bearing minerals it is concluded that regional scale transport and weathering of ultramafic derived constituents have resulted in enrichment of cr and ni in the sacramento valley and a partial change in the residence of cr

origin and hydrology of a large intact early cambrian paleocave system and its role in overlying fluidisation structures arctic canada abstract paleokarst is most commonly expressed as subtle stratigraphic surfaces rather than large void systems penetrating deeply into the paleo subsurface in contrast a regional precambrian cambrian unconformity on victoria island nwt canada is associated with exceptional exposure of large intact cambrian paleocaverns 100 m diameter tens of m high the paleocaves are distributed along a paleo horizontal plane and an associated gryke network is present in the 30 60 m of neoproterozoic dolostone between cave rooves and the base of overlying cambrian sandstone both are filled by cambrian sandstone the formation and preservation of such karst features require aggressive dissolution along a stable paleo water table shortly before transgression and deposition of shallow marine sand over the dolostone during the transgression the karst network acted as a conduit for flowing groundwater that was discharged through overlying unconsolidated cambrian shallow marine sand producing water escape structures sand volcanoes and their conduits the conduits are preserved as cylindrical remnants of the sand volcanoes feeder pipes sediment fluidisation was probably caused by variations in the hydraulic head gradient in a meteoric lens near the cambrian coastline under a tropical climate with abundant probably seasonally variable rainfall that caused pulses in subsurface fluid flow spatial distribution of the paleocaves and sand volcanoes suggests their formation on the southeast side of a recently faulted horst of proterozoic carbonate bedrock that formed a nearshore island during early cambrian sea level rise fluidisation structures such as those reported here have generally been difficult to interpret owing to a lack of data on the fluid hydraulics of the underlying aquifer this is the first report linking the hydraulics of a well characterised paleokarst to development of fluid escape structures such structures are widely known from sandstones overlying the sub cambrian unconformity around the circumference of laurentia

origin and mobility of hexavalent chromium in north eastern attica greece abstract an integrated framework that is comprised of field surveys of groundwater surface water and soils laboratory process experiments and hydrologic and geochemical modeling is used to identify the origin anthropogenic versus geogenic sources fate and transport of hexavalent cr in tertiary and quaternary deposits of oropos plain in greece groundwater and soils were analyzed in may 2008 and exhibited considerable cr concentrations mineralogical analysis and micro xrf analysis of the heavy soil fractions metallic components showed cr bearing phases like chromites cr silicate phases with positive correlation between si al fe and cr soil concentrations column experiments showed the cr vi desorption ability of soils e g concentration of 20 g l 1 was detected after the application of 50 mm of rain the groundwater model simulated the variability of cr concentrations emanating from both anthropogenic and geogenic sources successfully using rate constants obtained from the laboratory experiments e g 4 24 nm h 1 for serpentine soil and 0 77 nm h 1 for soil in alluvial deposits the mineralogical and geochemical results support a geogenic origin for cr in soils and groundwater of oropos plain while modeling results suggest that contaminants transported by asopos river have affected only the upper layers of the subsurface in the vicinity of the river the framework can be used to establish background concentrations or clean up levels of cr contaminated soils and groundwater

middle and low latitude ionosphere response to 2015 st patrick s day geomagnetic storm this paper presents a study of the st patrick s day storm of 2015 with its ionospheric response at middle and low latitudes the effects of the storm in each longitudinal sector asian african american and pacific are characterized using global and regional electron content at the beginning of the storm one or two ionospheric positive storm effects are observed depending on the longitudinal zones after the main phase of the storm a strong decrease in ionization is observed at all longitudes lasting several days the american region exhibits the most remarkable increase in vertical total electron content vtec while in the asian sector the largest decrease in vtec is observed at low latitudes using spectral analysis we were able to separate the effects of the prompt penetration of the magnetospheric convection electric field ppef and of the disturbance dynamo electric field ddef on the basis of ground magnetic data concerning the ppef earth s magnetic field oscillations occur simultaneously in the asian african and american sectors during southward magnetization of the b z component of the interplanetary magnetic field concerning the ddef diurnal magnetic oscillations in the horizontal component h of the earth s magnetic field exhibit a behavior that is opposed to the regular one these diurnal oscillations are recognized to last several days in all longitudinal sectors the observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models

from sumatra 2004 to tohoku oki 2011 the systematic gps detection of the ionospheric signature induced by tsunamigenic earthquakes the recent tsunamigenic earthquake in tohoku 11 march 2011 strongly affirms one more time after the sumatra event 26 december 2004 the necessity to open new paradigms in oceanic monitoring detection of ionospheric anomalies following the sumatra tsunami demonstrated that ionosphere is sensitive to the tsunami propagation observations supported by modeling proved that tsunamigenic ionospheric anomalies are deterministic and reproducible by numerical modeling via the ocean neutral atmosphere ionosphere coupling mechanism in essence tsunami induces internal gravity waves propagating within the neutral atmosphere and detectable in the ionosphere most of the ionospheric anomalies produced by tsunamis were observed in the far field where the tsunami signature in the ionosphere is clearly identifiable in this work we highlight the early signature in the ionosphere produced by tsunamigenic earthquakes and observed by gps measuring the total electron content close to the epicenter we focus on the first hour after the seismic rupture we demonstrate that acoustic gravity waves generated at the epicenter by the direct vertical displacement of the source rupture and the gravity wave coupled with the tsunami can be discriminated with theoretical support we illustrate the systematic nature of those perturbations showing several observations nominally the ionospheric perturbation following the tsunamigenic earthquakes in sumatra on 26 december 2004 and 12 september 2007 in chile on 14 november 2007 in samoa on 29 september 2009 and the recent catastrophic tohoku oki event on 11 march 2011 based on the analytical description we provide tracks for further modeling efforts and clues for the interpretation of complex and thus often misleading observations the routine detection of the early ionospheric anomalies following the rupture highlights the role of ionospheric sounding in the future ocean monitoring and tsunami detection

occurrence of hexavalent chromium in ground water in the western mojave desert california abstract about 200 samples from selected public supply domestic and observation wells completed in alluvial aquifers underlying the western mojave desert were analyzed for total dissolved cr and cr vi because cr vi is difficult to preserve samples were analyzed by 3 methods chromium vi was determined in the field using both a direct colorimetric method and epa method 218 6 and samples were speciated in the field for later analysis in the laboratory using a cation exchange method developed for the study described in this paper comparison of the direct colorimetric method and epa method 218 6 with the new cation exchange method yielded r 2 values of 0 9991 and 0 9992 respectively total dissolved cr concentrations ranged from less than the 0 1 g l detection limit to 60 g l and almost all the cr present was cr vi near recharge areas along the mountain front ph values were near neutral dissolved o 2 concentrations were near saturation and cr vi concentrations were less than the 0 1 g l detection limit chromium vi concentrations and ph values increased downgradient as long as dissolved o 2 was present however low cr vi concentrations were associated with low dissolved o 2 concentrations near ground water discharge areas along dry lakes chromium vi concentrations as high as 60 g l occurred in ground water from the sheep creek fan alluvial deposits weathered from mafic rock derived from the san gabriel mountains and cr vi concentrations as high as about 36 g l were present in ground water from alluvial deposits weathered from less mafic granitic metamorphic and volcanic rocks chromium iii was the predominant form of cr only in areas where dissolved o 2 concentrations were less than 1 mg l and was detected at a median concentration of 0 1 g l owing to its low solubility in water of near neutral ph depending on local hydrogeologic conditions and the distribution of dissolved o 2 cr vi concentrations may vary considerably with depth samples collected under pumping conditions from different depths within wells show that cr vi concentrations can range from less than the 0 1 g l detection limit to 36 g l in a single well and that dissolved o 2 concentrations likely control the concentration and redox speciation of cr in ground water

duskside enhancement of equatorial zonal electric field response to convection electric fields during the st patrick s day storm on 17 march 2015 the equatorial zonal electric field responses to prompt penetration of eastward convection electric fields ppef were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 march 2015 at dusk sector indian longitudes a rapid uplift of equatorial f layer to 550 km and development of intense equatorial plasma bubbles epbs were observed these epbs were found to extend up to 27 13 n and 25 98 s magnetic dip latitudes indicating their altitude development to 1670 km at apex in contrast at few degrees east in the premidnight sector thailand indonesian longitudes no significant height rise and or epb activity has been observed the eastward electric field perturbations due to ppef are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo idd fields whereas they were mostly counter balanced by the idd fields in the premidnight sector in situ observations from swarm a and swarm c and communication navigation outage forecasting system satellites detected a large plasma density depletion near indian equatorial region due to large electrodynamic uplift of f layer to higher than satellite altitudes further this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator this study brings out the significantly enhanced equatorial zonal electric field in response to ppef that is uniquely confined to dusk sector the responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field bz

new sequence perspective on the devonian reef complex and the frasnian famennian boundary canning basin australia the application of concepts of sequence stratigraphy to seismic and well data has led to a new understanding of the subsurface devonian reef complex of the canning basin it demonstrates marked reciprocal sedimentation with lowstand terrigenous sediments largely restricted to the basin and transgressive and highstand carbonate sediments on the platform preliminary outcrop studies indicate the potential of these concepts to modify significantly the existing lithostratigraphic and biostratigraphic interpretations of this classic exhumed reef complex including the stratigraphic context of the frasnian famennian boundary in the canning basin

comparison of δ 53 cr cr vi values of contaminated groundwater at two industrial sites in the eastern u s with contrasting availability of reducing agents abstract natural attenuation of groundwater contaminated by toxic hexavalent chromium cr vi was studied at two industrial sites in the eastern u s concentration and isotope composition of the residual cr vi were determined at site a in connecticut whose aquifer was polluted by electroplating solutions between 1930 and 1995 and at site b in new jersey whose aquifer was polluted by soluble chromium processing wastes between 1911 and 1963 site a was characterized by lower mean cr vi concentrations 2 mg l 1 and lower mean 53crcr vi values 1 84 in groundwater than site b 200 mg l 1 and 2 89 respectively 53crcr vi values were strongly positively correlated with dissolved organic carbon doc p 0 002 but not with dissolved ferrous iron fe ii or divalent manganese mn ii indicating that doc may have played a major role in spontaneous reduction of the mobile carcinogenic cr vi to immobile non toxic cr iii at site b the supply of doc may be nearly unlimited due to the presence of a buried organic meadow mat at a depth of six meters below the ground surface at site a contaminated groundwater has been extracted and treated since 1995 the mean 53crcr vi values of the residual aqueous contamination at site a significantly decreased over the past 15 years p

reefal platform development devonian of the canning basin western australia growth of devonian reefal limestone platforms on the canning basin was nearly continuous from the late givetian to the late famennian the earliest givetian and early frasnian platforms were low relief banks later frasnian and famennian platforms were normally reef rimmed with high relief upright reef margins predominated in the frasnian with intervals of backstepping associated with widespread drowning and the development of pinnacle reefs a brief emergence occurred at the frasnian famennian boundary and the succeeding famennian platforms advanced basinward over equivalent marginal slope and basin facies platform extinction in the late famennian resulted from abrupt drowning an important initial control on platform trends was basement topography resulting from middle devonian or older faulting continued faulting during the late devonian influenced the morphology of some platforms contemporary seismicity also led to neptunian fracturing and the collapse of platform margins the hypothetical sea level curve for the canning basin devonian is believed to be a combined result of global eustatism and regional diastrophism it shows gross resemblance to the equivalent euramerican curve rates of sea level rise or subsidence are thought to have largely controlled platform evolution banks and advancing platforms were associated with slow rises in sea level upright reef scarpsmore with moderately rapid rises and backstepping pinnacle reefs and drowning with very rapid rises shoaling upward cycles in back reef limestones resulted from periodic abrupt rises of a few meters followed by longer stillstands seismic stratigraphic modeling together with observed seismic records and well data suggest that the evolutionary model for the devonian platforms deduced from outcrop studies can also be applied in the subsurface less

atmospheric airglow fluctuations due to a tsunami driven gravity wave disturbance 1 a spectral full wave model is used to study the upward propagation of a gravity wave disturbance and its effect on atmospheric nightglow emissions gravity waves are generated by a surface displacement that mimics a tsunami having a maximum amplitude of 0 5 m a characteristic horizontal wavelength of 400 km and a horizontal phase speed of 200 m s the gravity wave disturbance can reach f region altitudes before significant viscous dissipation occurs the response of the oh meinel nightglow in the mesopause region 87 km altitude produces relative brightness fluctuations which are 1 of the mean for overhead viewing the wave amplitudes grow as the wave disturbance propagates upward which causes the thermospheric nightglow emission responses to be large for overhead viewing the brightness fluctuations are 50 and 43 of the mean for the oi 6300 a and o 1356 a emissions respectively the total electron content fluctuation is 33 of the mean for overhead viewing for oblique viewing the relative brightness fluctuations are slightly smaller than those obtained for overhead viewing in spite of this the thermospheric nightglow brightness fluctuations are large enough that oblique viewing could provide early warning of an approaching tsunami thus the monitoring of thermospheric nightglow emissions may be a useful augmentation to other observational techniques of tsunami effects in the thermosphere ionosphere system

changes of chromium concentration in alluvial sediments of the obra river valley in this research work changes in concentration of the chosen chemical element in alluvial sediments have been used to estimate the relative age of floodplain deposits the research concerning changes of chromium concentration in alluvial deposits was done in the obra river valley near miedzyrzecz western poland chromium was chosen because of its low ability to migrate in groundwater environment moreover this chemical element was used in the process of dyeing textures in miedzyrzecz between the sixteenth and the nineteenth century confrontation of changes in chromium concentration and age of alluvial sediments age estimated in years bp using radiocarbon method have shown that the sediments with higher chromium contents are much older than the period of development of the weaving industry in miedzyrzecz therefore it is not possible to use changes in chromium concentration to estimate relative age of floodplain sediments despite information in the literature about low migration ability of this chemical component macioszczyk and dobrzynski in hydrogeochemia strefy aktywnej wymiany wod podziemnych pwn warszawa 2002 ball and izbicki in appl geochem 19 1123 1135 2004 migration of chromium is so intensive that distinct changes in its concentration are observed even before the period of increased human activity

planetary magnetic signature of the storm wind disturbance dynamo currents ddyn 1 during magnetic storms joule heating and ion drag in auroral zones strongly influence the circulation of thermospheric neutral winds joule heating produces equatorward neutral winds at f region heights with return flow at e region altitudes around the equator the so called hadley cell the modified thermospheric circulation produces upwelling of molecule enriched air at high latitudes and global changes in the atmospheric composition the equatorward neutral winds extending from the auroral zone to mid and low latitudes through the coriolis force create westward storm wind which drives an equatorward dynamo current in this paper we detect for the first time in the three longitude sectors the planetary magnetic signature ddyn of ionospheric disturbance dynamo with its main features 1 the decrease of the equatorial electrojet due to a westward electric current flow opposite to the regular eastward current flow and 2 the equatorward ionospheric disturbance dynamo currents at midlatitudes

siliciclastic stromatolites and thrombolites late miocene s e spain abstract large coarse grained siliciclastic stromatolite and thrombolite domes forming biostromes and bioherms occur in a marine fan delta environment of messinian age in the sorbas basin spain individual domes are up to 3 m in height and have estimated synoptic relief up to 1 5 m they occur on a shelf to basin transition in the terminal complex a mixed siliciclastic carbonate unit which grades from coarse conglomeratic fan delta and oolite deposits on the shelf to basinal sands and silts of the sorbas member paleoslopes up to 35 degrees extending downward for several hundred of meters to original water depths of 70 m or more mark the transition to the basin normal marine conditions are indicated by coralline algae and porites within the domes thrombolites are restricted to he shelf and upper slope and are closely associated with stromatolites the domes of the mid slope and deeper environments are exclusively stromatolitic medium to coarse siliciclastic sand is common in domes at all depths except on the inner shelf where ooids are dominant quartz and metamorphic rock pebbles and granules are locally present in the thrombolites and stromatolites of the shelf edge and upper slope and boulders form nuclei of some of these domes carbonate grains mainly ooids and peloids are present in all domes however the dominant carbonate component is mainly micrite in the form of micro bushes and clotted fabrics important controls in the formation of these siliciclastic stromatolites and thrombolites were 1 supply of siliciclastic grains and 2 early carbonate cementation to maintain the relief of the domes during formation and to preserve primary fabrics after burial depth limited microbial components of the mats probably algae may have assisted in trapping coarse sediment they were also possibly responsible for limitation of the thrombolites to the shallow shelf environment

palaeokarst tidal erosion surfaces and stromatolites in the silurian eke formation of gotland sweden irregular scalloped erosion surfaces in the shelf carbonate sequences of the lower eke formation ludlow series upper silurian in the east of gotland sweden comprise series of shallow hollows separated by sharp crested ridges and cavities with sculptured undercut walls cut into lithified sediment these represent analogues of the solution basins formed in modern coastal and subaerial karst terrains discrete erosional cavities merge on enlargement by breaching of the intervening walls to leave remnant tapering ridges sets of the ridges and basins seen in surface view show an average width of basins of 1 2 m with relief of 40 50 cm and pronounced n s axes for the ridges this alignment may reflect the local drainage direction the lowermost erosion surface passes laterally into a planar mineralized horizon at the top of the underlying hemse group that was resistant to and forms the base level of erosion because of restricted exposure of higher eke formation sediments the upper limit of erosion remains unknown there is no evidence of caliche or subaerial diagenetic textures but solution vugs are common in the eroded limestones marine hard bottom biota attached to some surfaces and transition from scalloped to planar surfaces indicate erosion in tidal zones but subaerial karstic erosion is also inferred the resubmerged karst eroded topography is overlain by shallow marine carbonates including small organic buildups finely layered stromatolitic mats developed over the initial infill in subtidal environments and grew to form domed mounds within the erosional cavities they abut sharply against bounding side walls and overhangs some emergence is evident from desiccation features in the upper parts of mounds biostratigraphical evidence dating the events from initial uplift and karstic erosion to covering of the drowned relief topography places the whole sequence within upper ludlow times

natural cr vi contamination of groundwater in the cecina coastal area and its inner sectors tuscany italy a detailed hydrogeochemical study of groundwater in the cecina coastal plain livorno province italy and its inner sectors was undertaken in 2008 as chemical analyses carried out on groundwater since 2006 have revealed cr vi concentrations of up to 49 g l well above the permissible limit of 5 g l ophiolite outcrops are present throughout the study area and their fragments likely represent a significant portion of the existing multilayered aquifer skeleton waters delivered by the serpentinite outcrops have a typically mg hco3 composition whereas those of the coastal plain are prevailingly of the ca mg hco3 type with significant mg contents significant no3 contamination characterises the studied coastal plain and an interesting negative correlation exists between cr vi and both no3 and so4 deriving from the widespread use of nh4 2so4 as a farm fertilizer chromium speciation calculations carried out using the eq3nr code reveal that the prevailing cr vi species in solution is cro4 2 however cacro4 and mgcro4 neutral complexes represent significant percentages up to 42 these findings suggest that the mobility and consequently the bioavailability of cr vi can be significantly enhanced by these neutral complexes which are not considered to be affected by adsorption desorption processes the cr vi source investigated by means of the mg sio2 molar ratio seems to be represented mainly by mg bearing minerals of the chlorite group petrographic observations confirm the occurrence of this mineral group the interaction between rainwater and the local serpentinite rock was simulated at different p text co 2 and p text o 2 conditions by reaction path modelling using the eq3 6 software package p text o 2 was varied in accordance with the assumption that redox conditions are determined in part by no3 results are in good agreement with experimental data on spring waters and subordinately with data on some coastal plain groundwater which plot in a rather wide p text co 2 and p text o 2 field although the dissolved cr content is mostly of natural origin fertilization may affect its fate

stable chromium isotopic composition of meteorites and metal silicate experiments implications for fractionation during core formation we present new mass independent and mass dependent cr isotope compositions for meteorites measured by double spike thermal ionisation mass spectrometry small differences in both mass independent 53cr and 54cr relative to the bulk silicate earth are reported and are very similar to previously published values carbonaceous chondrites are characterised by an excess in 54cr compared to ordinary and enstatite chondrites which make mass independent cr isotopes a useful tool for distinguishing between meteoritic groups mass dependent stable cr isotope compositions for the same samples are also reported carbonaceous and ordinary chondrites are identical within uncertainty with average 53cr values of 0 118 0 040 and 0 143 0 074 respectively the heaviest isotope compositions are recorded by an enstatite chondrite and a co carbonaceous chondrite both of which have relatively reduced chemical compositions implying some stable cr isotope fractionation related to redox processes in the circumstellar disk the average 53cr values for chondrites are within error of the estimate for the bulk silicate earth bse also determined by double spiking the lack of isotopic difference between chondritic material and the bse provides evidence that cr isotopes were not fractionated during core formation on earth a series of high pressure experiments was also carried out to investigate stable cr isotope fractionation between metal and silicate and no demonstrable fractionation was observed consistent with our meteorites data mass dependent cr isotope data for achondrites suggest that cr isotopes are fractionated during magmatic differentiation and therefore further work is required to constrain the cr isotopic compositions of the mantles of vesta and mars

famennian microbial reef facies napier and oscar ranges canning basin western australia following the frasnian famennian mass extinction which eliminated most skeletal reef building fauna the early famennian reefs of the canning basin were constructed primarily by reef framework microbial communities in the napier and oscar ranges the famennian reef complexes had high energy reef flat depositional environments on a reef rimmed platform that transitioned into low energy deep water reefs growing in excess of 50 m below sea level high energy reef flat depositional environments contain doming fenestral stromatolites that grade into porous thrombolites and are associated with coarse grained sandstones and grainstones the reef margin subfacies contains mounds of microdigitate thrombolites which are more delicate than the reef flat thrombolites and locally contain abundant red algae girvanella renalcids and sediment filled tubes within the thrombolites the red algae are in upright growth positions suggesting that the thrombolites are largely composed of carbonate that precipitated in situ reefal slope environments are dominated by wetheredella and rothpletzella with locally abundant girvanella renalcids and uralinella in reefal slope strata delicate fans and microdigitate stromatolites of wetheredella and rothpletzella are often oriented horizontal or diagonal to bedding and are interpreted as syndepositionally toppled over most mesoscale microbial community structures contain several species of microbial fossils and no single microbial species appears to have controlled the morphology of the community structure therefore the depositional environment must have determined the distribution and morphology of the stromatolites thrombolites and other microbial community structures the adaptability of microbial communities to various reef environments allowed them to fill ecological niches opportunistically after the frasnian famennian mass extinction

high resolution vertical e b drift model derived from rocsat 1 data 1 the measurements of vertical ion velocity from the first republic of china satellite rocsat 1 provide a unique database for the development of an annually and longitudinally high resolution vertical plasma drift model in the equatorial ionosphere currently the rocsat 1 based empirical vertical drift models are available for three seasons equinox and solstices however the vertical drift patterns are not precisely divided by the three seasons a monthly vertical drift model with high longitudinal resolution is desirable to accurately model the low latitude ionosphere and to identify the coupling between the ionosphere and atmospheric tide here we introduce an empirical vertical drift model derived by using the rocsat 1 data in three solar flux conditions f 10 7 180 under k p 3 the local time day of the year and longitude of the model are binned by 15 min 1 month and 10 respectively under each solar flux condition our vertical drift model is validated by comparing the model with the measurements of the vertical drift velocity at the jicamarca radio observatory the characteristics and variability of the vertical drift are briefly discussed

geochemical constraints on the sources of cr vi contamination in waters of messapia central evia basin the present study aims to define geochemical constraints on contamination source s by cr vi in central evia through a compilation of new and literature data on an integrated set of approaches including mineralogy and isotope geochemistry leach experiments on rocks soils and ni laterites and comparison with literature data on groundwater the concentrations of cr vi in leachates from various geological materials decrease in the following order ni laterites from kastoria soils altered ultramafic rocks ni laterites from evia a salient feature is the diversity in the cr vi concentrations and 53cr values in a groundwater ranging from 2 to 850 g l cr vi and 0 60 1 99 53cr and b leachates from ni laterites ranging from 0 6 to 2 0 g l and 1 01 in evia samples and from 750 to 1200 g l and negative to slightly positive 0 21 to 0 03 53cr in kastoria samples a positive correlation r2 0 514 between the 53cr values and depth of the aquifers potentially reflects the decrease in soluble o2 with increasing depth the relatively high cr mn and the abundance of fine grained mn hydr oxides in the kastoria laterite ore may be major controlling factors for the existence of high cr vi concentrations in the water leachates in contrast the low cr vi concentrations and positively fractionated cr isotopes in the ni laterite leachates from evia are potentially related to redox and multistage transportation redeposition processes the positive correlation between cr concentrations and ca mg ratios r2 0 647 for rock leachates and the negative correlation r2 0 694 for soil leachates suggest that cr in groundwater may be released mainly from cr bearing mg silicates in altered ultramafic rocks and soils the plot of 53cr values versus cr vi concentrations for the contaminated waters from central evia and assopos basin fall within both fields defined from a global database for natural waters and waters contaminated by human activities

are reefs and mud mounds really so different although both ecologic reefs and mud mounds are demonstrably rigid framework reefs they are still considered to be distinct in terms of their dominant processes of formation and preferred environmental settings this distinction has rested largely upon the assumption that ecologic reefs are dominated by skeletal metazoans growing in shallow waters in contrast to the complex autochthonous micrite supported cavity systems that characterise deep water mud mounds now considered to represent either organomineralic deposits where carbonate precipitation has taken place in association with nonliving organic substrates to form automicrite or various types of microbialite where carbonate forms as a direct result of the physiological activity or decay of benthic microorganisms yet such autochthonous micrite is increasingly recognised as an important component of many ancient shallow ecologic reefs as well as some modern coral reefs and indeed may contribute locally up to 80 of the reef rock these observations raise doubts as to the validity of current fabric based definitions used to distinguish between mud mounds and ecologic reefs whether the autochthonous micrite in mud mounds proves to be dominated by either automicrite or microbialite both require particular environmental conditions for their formation automicrites form where surplus organic matter from metazoans has degraded to release quantities of acidic amino acids with a significant ability to bind ca 2 and microbialite formation also often requires either unusual marine chemistries or ecological conditions such conditions might include changes in terrigenous influx ground water seepage local anoxia and increases in the ph of interstitial reef waters or in nutrient concentration d 2001 elsevier science b v all rights reserved

pliocene pleistocene sedimentary and geomorphologic development of the vasilikos river catchment s cyprus in relation to uplift of the troodos ophiolite and climate related changes the pleistocene development of the vasilikos river exemplifies the interaction of focused tectonically induced surface uplift and climate influenced changes the resulting sediments are well exposed in vasilikos quarry and in the main river catchment further east an important erosional surface incises the highest level oldest fluvial conglomerates down into late pliocene early pleistocene open marine mudrocks nicosia formation allowing integration with the circum cyprus sedimentary geomorphic development f1 f4 stages to determine where the quarry deposits lie in relation to the vasilikos river catchment the fluvial deposits were mapped and valley profiles were constructed revealing four main episodes each associated with incision and distinctive fluvial deposition source lithology strongly influenced channel morphology infill and adjacent slope sediment colluvium composition palaeosols particularly red brown terra rossa developed on abandoned fluvial terraces and adjacent hillslopes especially overlying f3 surfaces the combined evidence allows close correlation of the vasilikos river and quarry deposits relatively coarse chalky conglomerate breccia and fine grained colluvium calcareous silt cyprus harvara developed especially on lower hillslopes following incision mainly above f2 and f3 surfaces based on regional comparisons overall sediment aggregation ended during the early pleistocene the f1 f2 surfaces and deposits are inferred to be middle pleistocene the f3 ones later middle pleistocene and the f4 ones near the middle late pleistocene boundary geomorphology and deposition were tectonically forced during strong focused early middle pleistocene surface uplift coarse clastic ruff off and palaeosol development terra rossa and related sediment aggradation are inferred to have increased during warm humid periods late pleistocene geomorphology and deposition were more influenced by climatic change with semi perennial streamflow rapid sediment aggradation and palaeosol terra rossa development during warm humid periods interglacials cooler glacial periods enhanced fluvial incision sediment bypassing and hillslope colluvial processes e g frost shattering downslope creep and mass flow when sediment transport bypassing exceeded sediment supply neotectonic faulting affected the catchment but did not greatly affect geomorphology or sediment supply although climate climate change and eustatic sea level change had an important influence tectonics is interpreted as the fundamental driver of geomorphological development and fluvial sedimentation with implications for other areas regionally to globally

weathering and transport of chromium and nickel from serpentinite in the coast range ophiolite to the sacramento valley california usa abstract a soil geochemical study in northern california was done to investigate the role that weathering and transport play in the regional distribution and mobility of geogenic cr and ni which are both potentially toxic and carcinogenic these elements are enriched in ultramafic rocks primarily serpentinite and the soils derived from them 1700 10 000 mg cr per kg soil and 1300 3900 mg ni per kg soil in the coast range ophiolite chromium and ni have been transported eastward from the coast range into the western sacramento valley and as a result valley soil is enriched in cr 80 1420 mg kg 1 and ni 65 224 mg kg 1 compared to median values of u s soils of 50 and 15 mg kg 1 respectively nickel in ultramafic source rocks and soils is present in serpentine minerals lizardite antigorite and chrysotile and is more easily weathered compared to cr which primarily resides in highly refractory chromite mg fe2 cr3 al fe3 2o4 although the majority of cr and ni in soils are in refractory chromite and serpentine minerals the etching and dissolution of these minerals presence of cr and ni enriched clay minerals and development of nanocrystalline fe hydr oxides is evidence that a significant fractions of these elements have been transferred to potentially more labile phases

effects of disturbed electric fields in the low latitude and equatorial ionosphere during the 2015 st patrick s day storm the 2015 st patrick s day geomagnetic storm with sym h value of 233 nt is an extreme space weather event in the current 24th solar cycle in this work we investigated the main mechanisms of the profound ionospheric disturbances over equatorial and low latitudes in the asian australian sector and the american sector during this super storm event the results reveal that the disturbed electric fields which comprise penetration electric fields pefs and disturbance dynamo electric fields ddefs play a decisive role in the ionospheric storm effects in low latitude and equatorial regions pefs occur on march 17 in both the american sector and the asian australian sector the effects of ddefs are also remarkable in the two longitudinal sectors both the ddefs and pefs show the notable local time dependence which causes the sector differences in the characteristics of the disturbed electric fields this differences would further lead to the sector differences in the low latitude ionospheric response during this storm the negative storm effects caused by the long duration ddefs are intense over the asian australian sector while the repeated elevations of hmf2 and the eia intensifications caused by the multiple strong pefs are more distinctive over the american sector especially the storm time f3 layer features are caught on march 17 in the american equatorial region proving the effects of the multiple strong eastward pefs

cr vi occurrence and geochemistry in water from public supply wells in california hexavalent chromium cr vi in 918 wells sampled throughout california between 2004 and 2012 by the groundwater ambient monitoring and assessment priority basin project gama pbp ranged from less than the study reporting limit of 1 microgram per liter g l to 32 g l statewide cr vi was reported in 31 percent of wells and equaled or exceeded the recently established 2014 california maximum contaminant level mcl for cr vi of 10 g l in 4 percent of wells cr vi data collected for regulatory purposes overestimated cr vi occurrence compared to spatially distributed gama pbp data ninety percent of chromium was present as cr vi which was detected more frequently and at higher concentrations in alkaline ph 8 oxic water and more frequently in agricultural and urban land uses compared to native land uses chemical isotopic tritium and carbon 14 and noble gas data show high cr vi in water from wells in alluvial aquifers in the southern california deserts result from long groundwater residence times and geochemical reactions such as silicate weathering that increase ph while oxic conditions persist high cr vi in water from wells in alluvial aquifers along the west side of the central valley results from high chromium in source rock eroded to form those aquifers and areal recharge processes including irrigation return that can mobilize chromium from the unsaturated zone cr vi co occurred with oxyanions having similar chemistry including vanadium selenium and uranium cr vi was positively correlated with nitrate consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return

saint santin radar observations of lower thermospheric storms incoherent scatter measurements of ion drift velocities obtained by saint santin nancay radar have been used to study the lower thermospheric wind disturbances during geomagnetic storms a storm time meridional circulation with equatorward wind velocities at higher altitudes 135 km is revealed the transition altitude below which the circulation reverses direction is also traceable the strength of the circulation is in good agreement with blanc and richmond s 1980 model simulation for intense storms some evidence is also found for phase variations in the semidiurnal tide during storm periods but its interpretation is difficult because of the restriction of the data to daytime hours

highly localized unique electrodynamics and plasma irregularities linked with the 17 march 2015 severe magnetic storm observed using multitechnique common volume observations from gadanki india in this paper we study equatorial electrodynamics and plasma irregularities linked with the 17 march 2015 severe magnetic storm in the indian sector using common volume observations made by the gadanki ionospheric radar interferometer airglow imager digisonde and gps receiver established at gadanki 13 5o n 79 2o e observations show that with the initiation of the storm at 6 ut on 17 march which happened to be midday in the indian sector the low latitude ionosphere responded in tune with the storm induced electric field and by the sunset time the base of the f layer ascended to an altitude of 470 km with a peak upward velocity of 50 m s 1 eventually manifesting equatorial plasma bubble and irregularities causing strong gps scintillation the most important finding found in this study is the confinement of plasma bubble and irregularities in a narrow longitude zone of 69o 98o e results also show reversal of zonal drift of the irregularities from 120 m s 1 eastward drift to 120 m s 1 westward drift in a time span of 30 min both observations are shown to be linked with very special electrodynamical conditions induced by the magnetic storm related electric field in the dusk sector intriguing details of the longitudinally localized electrodynamics and plasma irregularities are discussed in terms of prompt penetration and disturbed dynamo electric field effects

simulation of electric field and current during the 11 june 1993 disturbance dynamo event comparison with the observations 1 the ionospheric disturbance dynamo signature in geomagnetic variations is investigated using the national center for atmospheric research thermosphere ionosphere electrodynamics general circulation model the model results are tested against reference magnetically quiet time observations on 21 june 1993 and disturbance effects were observed on 11 june 1993 the model qualitatively reproduces the observed diurnal and latitude variations of the geomagnetic horizontal intensity and declination for the reference quiet day in midlatitude and low latitude regions but underestimates their amplitudes the patterns of the disturbance dynamo signature and its source anti sq current system are well reproduced in the northern hemisphere however the model significantly underestimates the amplitude of disturbance dynamo effects when compared with observations furthermore the largest simulated disturbances occur at different local times than the observations the discrepancies suggest that the assumed high latitude storm time energy inputs in the model were not quantitatively accurate for this storm

signature of the coronal hole near the north crest equatorial anomaly over egypt during the strong geomagnetic storm 5 april 2010 in this paper we study the ionospheric magnetic disturbance during a strong magnetic storm on 5 april 2010 associated to a coronal hole the earth was under the influence of a high speed solar wind stream during four days and imf was southward during a very long period the variation of the disturbed magnetic observations and gps tec are compared with the variation of quiet days during the same month in order to obtain the characteristics of gps tec and magnetic disturbances due to the coronal hole effect we use multi instruments as scinda gps station at helwan egypt 29 86 n 31 32 e and asw magdas station at aswan egypt 23 59 n 32 51 e in the equatorial region at the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field which strongly increases the tec during the recovery phase of the storm we observe on tec and magnetic data the signature of the ionospheric disturbance dynamo due to wind produced by joule heating in the auroral zone it is the first time that we observe an anti sq circulation on magnetic data during four consecutive days associated to the high speed solar wind streams

seasonal and longitudinal variation of large scale topside equatorial plasma depletions 1 we examine the large scale properties of three classes of equatorial topside plasma depletions referred to as channels in order of increasing zonal width and internal large scale substructuring we study simple channels multichannels and superchannels we find that peaks in channel activity are centered on 0 african sector and 180 western pacific sector superchannels are found to strongly dominate in the african sector whereas simple and multichannels dominate the pacific sector within the african sector the relative proportions of the three channel classes remain stable in all seasons in the pacific sector simple and multichannels are dominant in all seasons of activity though small but significant seasonal variations in channel widths and spacings are seen structure at a zonal scale size of about 100 km is found to be present in all channels examined observational and model evidence suggests that 100 km density structure represents channels such that all multichannels and superchannels consist of multiple contiguous simple channels since seeds that initiate channel formation necessarily influence large scale channel features we utilize our data to draw conclusions regarding bottomside seeding conditions in the various seasonal and longitudinal sectors specifically we find that strong long wavelength 1000 km seeds appear much more frequently in the african sector resulting in the prevalence of superchannels there when long wavelength seeds appear in the pacific sector they result in periodic trains of simple and multichannels a bottomside preseeded at a scale size near 100 km accounts for the ubiquity of 100 km scale size in the ae e data

electrodynamic coupling of high and low latitudes observations on may 27 1993 the penetration of disturbance electric fields from the polar region to the magnetic equator on the dayside of the earth is examined with geomagnetic data on may 27 1993 first we examine a dayside equatorial disturbance that followed the rapid recovery of magnetic activity from a storm and that has the characteristics of overshielding caused by persistent region 2 field aligned currents it lasted 0 3 hours second we analyze a series of fluctuations with periods of 25 75 min to determine the variations of amplitude and phase with magnetic latitude and magnetic local time the fluctuations were highly coherent at all latitudes between the magnetic equator and the auroral zone but the coherency decreasedin the polar cap a northward fluctuation at the equator during midday hours accompanied auroral zone fluctuations that were southward before noon eastward around noon and northward after noon the amplitudes decreased away from the auroral zone toward midlatitudes but were amplified under the equatorial electrojet no detectablep hased ifferencesa re found indicating that any temporal lags which might be inducedb y persistencein the region 2f ield alignedc urrentsa re less than i min for fluctuations having periods like those examined here a synoptic inversion analysis of the high latitude magnetic data to estimate the time varying high latitude electric potential patterns shows that fluctuations of the high latitude east west potential gradient tended to be concentrated around midday where they were in phase with fluctuations in the midday east west potential gradient at the magnetic equator

seasonal and longitudinal dependence of equatorial disturbance vertical plasma drifts 1 we used equatorial measurements from the rocsat 1 satellite to determine the seasonal and longitudinal dependent equatorial f region disturbance vertical plasma drifts following sudden increases in geomagnetic activity the prompt penetration vertical drifts are upward during the day and downward at night and have strong local time dependence at all seasons the largest prompt penetration drifts near dusk and dawn occur during june solstice the daytime disturbance dynamo drifts are small at all seasons they are downward near dusk with largest smallest values during equinox june solstice the nighttime drifts are upward with the largest magnitudes in the postmidnight sector during december solstice during equinox the downward disturbance dynamo drifts near sunset are largest in the eastern hemisphere while the late night upward drifts are largest in the western hemisphere the longitudinal dependence of the disturbance dynamo drifts is in good agreement with results from simulation studies

the recognition and interpretation of paleokarsts two examples from the lower carboniferous of south wales abstract criteria for the identification and interpretation of paleokarstic surfaces in ancient carbonate sequences are discussed and two examples of such surfaces are described from the lower carboniferous of south wales one type is compared to kavornossen karren a type of tropical karst well developed today on puerto rico the second example a mammillated paleokarstic surface of a type common in the lower carboniferous is interpreted as a deckenkarren formed beneath a vegetation cover and similar to the makondo karsts of south africa paleokarsts can provide information on the paleoclimates paleohydrology and vegetation cover existing at the time of their formation

study of the equatorial and low latitude electrodynamic and ionospheric disturbances during the 22 23 june 2015 geomagnetic storm using ground based and spaceborne techniques we use a set of ground based instruments global positioning system receivers ionosondes magnetometers along with data of multiple satellite missions swarm c nofs dmsp guvi to analyze the equatorial and low latitude electrodynamic and ionospheric disturbances caused by the geomagnetic storm of 22 23 june 2015 which is the second largest storm in the current solar cycle our results show that at the beginning of the storm the equatorial electrojet eej and the equatorial zonal electric fields were largely impacted by the prompt penetration electric fields ppef the ppef were first directed eastward and caused significant ionospheric uplift and positive ionospheric storm on the dayside and downward drift on the nightside furthermore about 45 min after the storm commencement the interplanetary magnetic field imf bz component turned northward leading to the eej changing sign to westward and to overall decrease of the vertical total electron content vtec and electron density on the dayside at the end of the main phase of the storm and with the second long term imf bz southward turn we observed several oscillations of the eej which led us to conclude that at this stage of the storm the disturbance dynamo effect was already in effect competing with the ppef and reducing it our analysis showed no significant upward or downward plasma motion during this period of time however the electron density and the vtec drastically increased on the dayside over the asian region we show that this second positive storm was largely influenced by the disturbed thermospheric conditions

responses in the polar and equatorial ionosphere to the march 2015 st patrick day storm the st patrick day storm of 2015 17 march 2015 occurred at a unique time when there were multiple spacecraft observing the earth s ionosphere between 350 and 885 km observations of the plasma flows and densities from the five operational polar orbiting dmsp spacecraft combined with those from the equatorial orbiting c nofs spacecraft provided a comprehensive global record of the both the polar and equatorial ionosphere regions responses to the storm this paper presents an overview of the data from this suite of spacecraft focusing on the following aspects 1 the polar cap ionosphere s reaction to the storm 2 the change in the penetration electric field in the midlatitude region as a function of time and the solar local time during the storm 3 the equatorial ionosphere s response of the meridional vertical flows to the penetration electric field and the disturbance dynamo during the storm and 4 the creation of a predawn ionospheric bubble system near the equator during the storm s main phase that was observed at low altitudes by c nofs and later at high altitudes by several dmsp examining these phenomenon enable us to trace the dynamic flow of energy from the solar wind input in the polar ionosphere all the way to the equatorial ionosphere

chromium chromium isotopes and selected trace elements western mojave desert usa abstract chromium vi concentrations in excess of the california maximum contaminant level mcl of 50 g l occur naturally in alkaline oxic ground water in alluvial aquifers in the western mojave desert southern california the highest concentrations were measured in aquifers eroded from mafic rock but cr vi as high as 27 g l was measured in aquifers eroded from granitic rock chromium vi concentrations did not exceed 5 g l at ph

anoxic oxidation of chromium naturally occurring cr vi has been ascribed to terrestrial cr iii oxidation by mn di oxides generated through reaction of mn ii with molecular oxygen o 2 however hydrogen peroxide h 2 o 2 is a potential oxidant of cr iii that may form in serpentinization high h 2 low o 2 systems where chromite i e the main mineralogical source of cr iii is abundant accordingly here we evaluate h 2 o 2 and chromite interactions in serpentinization systems to determine pathways of cr iii oxidation that alters the current paradigm of o 2 dependent oxidation field observations support that metastable h 2 o 2 and cr vi are present in serpentinization related fluids relatively absent of o 2 further laboratory experiments demonstrate and support that h 2 o 2 is a kinetically facile oxidant of chromite especially under alkaline conditions which provides a variety of alternative means by which cr vi may be generated and supplied to the oceans not directly linked to atmospheric o 2 thus cr iii oxidation pathways and their influence on the cr isotopic record must account for anoxic cr iii oxidation in serpentinization systems as well as a variety of h 2 o 2 induced cr iii oxidation pathways that may occur in both terrestrial and marine systems

longitudinal responses of the equatorial low latitude ionosphere over the oceanic regions to geomagnetic storms of may and september 2017 this study presents the longitudinal dependence of responses of the equatorial low latitude ionosphere over the oceanic regions to geomagnetic storms of 28th may and 8th september 2017 we investigated the interplanetary origins of the storms total electron content tec data were obtained from global navigation satellite system stations located around the oceanic areas in the equatorial low latitude regions the rate of change of tec index roti was used as a proxy for ionospheric irregularities over the study locations further variations of the horizontal component of the earth s magnetic fields obtained from ground based magnetometers were studied we used ionospheric disturbance currents polar cap and auroral electrojet indices to monitor the storm time electric fields the may 2017 storm was driven by sheath and magnetic cloud fields while the september 2017 storm was driven by sheath fields we observed a comparative dominance of tec intensities over the oceans than over the landlocked areas empirically our results validated a theoretical suggestion of the existence of a dynamic ocean ionosphere coupling made by godin et al 2015 prompt penetration electric fields ppef was observed to be a key factor that controls tec responses to storms ppefs caused tec enhancements mainly over the pacific ocean longitudes during the may 2017 storm and enhanced tec over the atlantic ocean and the pacific oceans longitudes during the september 2017 storm these ppefs triggered irregularities over the pacific

magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes ddyn 1 during magnetic storms wind disturbances produced by auroral phenomena can affect the whole thermospheric circulation and associated ionospheric dynamo currents for many hours after the end of the storms in this paper we define criteria to select a new simple type of ionospheric disturbance dynamo events that allow a simple interpretation over all longitude sectors these events exhibit a weak auroral activity during at least 24 ut hours on the day after the storm we analyze the magnetic disturbances ddyn observed at equatorial latitudes in the three longitude sectors of such selected events it is found for all the cases that the amplitude of the h component of the earth s magnetic field is reduced on the day after storm at equatorial latitudes in agreement with the ionospheric disturbance dynamo model blanc and richmond 1980 the observation of h component decrease on the day after storm is longitudinally asymmetric the observed signature of the ionospheric disturbance dynamo process in a specific longitude sector is strongly dependent on the magnitude the start time and the duration of the storm

platform margin collapse during famennian reef evolution canning basin western australia sedimentological investigations of well exposed slope strata in the upper devonian reef complexes of the northern canning basin lead to a sequence stratigraphic interpretation that differs from others based on predictive models in which coarse carbonate debris deposits are regarded as lowstand deposits in the upper frasnian famennian napier range slope succession we recognize an important phase of platform margin collapse during a sea level highstand in the middle famennian at this time the reef rimmed margin was rapidly prograding and the platform was producing carbonate grains notably ooids and peloids that were being transported by turbidity currents to the slope and basin floor periodic collapse of the platform margin led to deposition on the slope of allochthonous blocks of reefal limestone and channelized debris flow units intercalated with the ooid peloidal turbidites and quartzo feldspathic sandstones collapse of the early cemented margin was probably triggered by gravitational instability caused by oversteepening during rapid progradation and or tectonic activity with falling blocks initiating some of the debris flows

quasi 16 day oscillation in the mesosphere and lower thermosphere a quasi 16 day wave in the mesosphere and lower thermosphere is investigated through analyses of radar data during january february 1979 and through numerical simulations for various background wind conditions previous workers have examined about 19 days of tropospheric and stratospheric data during january 10 28 1979 and present conflicting evidence as to whether a large westward propagating wavenumber 1 oscillation observed during this period can be identified in terms of the second symmetric rossby normal mode of zonal wavenumber 1 commonly referred to as the 16 day wave in the present work we have applied spectral analysis techniques to meridional and zonal winds near 95 km altitude obtained from radar measurements over obninsk russia 54 n 38 e and saskatoon canada 52 n 107 w these data reveal oscillations of the order of 10 m s 1 with a period near 16 days as well as waves with periods near 5 and 10 days these periodicities all correspond to expected resonant frequencies of atmospheric disturbances associated with westward propagating free rossby modes of zonal wavenumber 1 numerical simulations are performed which demonstrate that the 95 km measurements of the 16 day wave are consistent with upward extension of the oscillation determined from the tropospheric and stratospheric data noteworthy features of the model in terms of its applicability in the mesosphere lower thermosphere regime are explicit inclusion of eddy and molecular diffusion of heat and momentum and realistic distributions of mean winds especially between 80 and 100 km the latter include a westerly wind regime above the summer easterly mesospheric jet thus providing a ducting channel enabling interhemispheric penetration of the winter planetary wave disturbance this serves to explain the appearance of a quasi 16 day wave recently reported in the high latitude summer mesopause williams and avery 1992 however the efficiency of this interhemispheric coupling may be reduced by gravity wave stress no significant penetration of the 16 day oscillation above about 100 km is predicted by the model reported signatures of a 16 day periodicity in ionospheric data therefore require modulation of tidal or gravity wave accessibility to the thermosphere or perhaps in situ excitation

was magnetic storm the only driver of the long duration enhancements of daytime total electron content in the asian australian sector between 7 and 12 september 2017

geochemistry and cr stable isotopes of cr contaminated groundwater in leon valley guanajuato mexico abstract leon valley located in the mexican state of guanajuato has a long history 35 a of cr contamination of groundwater and surface water here data are presented for cr major ion and trace element concentrations and cr stable isotope measurements of groundwater in a heavily contaminated aquifer in buenavista where cr ore processing residue piles coprps located in a chromate production factory are the main source of cr the aquifer directly beneath the factory still retains very high cr vi concentrations 121 mg l ongoing pump and treat remediation is keeping the high concentration plume confined to the factory area and immediate vicinity though cr is also detected at some distance away chromium isotope data of the aquifer directly under the factory show only a small increase in 53 cr 0 33 to 0 81 and indicates minimal reduction of cr vi to cr iii very high cr vi concentrations have possibly overwhelmed natural reductants and furthermore fresh cr vi was being leached into the groundwater from the coprp from just one year of cr isotope data it is clear that more aggressive remediation techniques will be necessary to reduce or eliminate the contamination the fringes of the cr plume have substantially lower concentrations and can be partially explained by transport of the main plume or mixing between waters from the nearby landfill and highly contaminated waters from qc while the source of cr at the fringes of the plume could be attributed to a source from the nearby landfill instead of the main plume from the factory the cr stable isotope data show enrichment in the heavier isotopes and point to varying amounts of reduction isotopic enrichment seen between 2007 and 2008 along the fringe may indicate either reduction or less unreacted cr vi is being transported to the fringes in either case some potential for natural attenuation of cr vi exists at the western margin of the plume with the landfill playing a role

geochemistry of natural chromium occurrence in a sandstone aquifer in bauru basin sao paulo state brazil abstract anomalous concentrations of cr vi occur in groundwaters of the adamantina aquifer in a large region in the western state of sao paulo sometimes exceeding the potability limit 0 05 mg l 1 to identify the possible geochemical reactions responsible for the occurrence of cr in groundwater in ur nia borehole rock samples were collected in order to carry out mineralogical and chemical analyses in addition multilevel monitoring wells were installed and groundwater samples were analyzed analyses of the borehole rock samples show the occurrence of a geochemical anomaly of cr in the quartzose sandstones average concentrations of 221 ppm chrome diopside is one of the main minerals contributing to this anomaly having an average cr content of 1505 ppm sequential extraction experiments indicated weakly adsorbed cr in the order of 0 54 ppm and this quantity is enough to provide the cr concentrations observed in groundwater groundwaters from the monitoring wells proved to be stratified with the highest concentrations of cr vi 0 13 mg l 1 being associated with high redox and ph values over 10 and high concentrations of na geochemical reactions that may explain the release of cr from the solid phase to groundwater involve the release of cr iii from minerals like chrome diopside and cr fe hydroxide followed by oxidation of cr iii to cr vi probably related to the reduction of mn oxides present in the aquifer then cation exchange occurs and dissolution of carbonates which increases the ph of groundwater resulting in the desorption and mobilization of cr vi into groundwater

global equatorial plasma bubble occurrence during the 2015 st patrick s day storm an analysis of the occurrence of equatorial plasma bubbles epbs around the world during the 2015 st patrick s day geomagnetic storm is presented a network of 12 global positioning system receivers spanning from south america to southeast asia was used in addition to colocated vhf receivers at three stations and four nearby ionosondes the suppression of postsunset epbs was observed across most longitudes over 2 days the epb observations were compared to calculations of the linear rayleigh taylor growth rate using coupled thermosphere ionosphere modeling which successfully modeled the transition of favorable epb growth from postsunset to postmidnight hours during the storm the mechanisms behind the growth of postmidnight epbs during this storm were investigated while the latter stages of postmidnight epb growth were found to be dominated by disturbance dynamo effects the initial stages of postmidnight epb growth close to local midnight were found to be controlled by the higher altitudes of the plasma i e the gravity term modeling and observations revealed that during the storm the ionospheric plasma was redistributed to higher altitudes in the low latitude region which made the plasma more susceptible to rayleigh taylor growth prior to the dominance of the disturbance dynamo in the eventual generation of postmidnight epbs

distribution and geometry of facies and early diagenesis the key to accommodation space variation and sequence stratigraphy upper cretaceous congost carbonate platform spanish pyrenees abstract through only moderate structural deformation the upper cretaceous carbonates of the tremp region in the spanish pyrenees can be studied in the form of a platform to basin cross section comparable in scale to that of a seismic section this study examines the upper turonian to mid coniacian congost platform and its associated basinal succession the sedimentology facies geometries and cycle stacking patterns along with evidence of exposure of the platform are interpreted in terms of fluctuations in relative sea level and variations in accommodation space differences in the facies and early diagenesis of carbonates from different parts of the congost platform suggest two separate phases of platform development an earlier more land ward platform was dominated by clinoforms prograding on to a sloping basin floor with a thin lagoonal sand bank facies upon the platform itself supplying abundant excess sediment to the clinoforms a later more basin ward platform has a more complex internal geometry of depositional units and marginal rudist coral buildups the interpretations are used to propose a new sequence stratigraphic architecture for the congost platform involving two sequences the second produced through dynamic forced regression sequence boundaries are characterised by subaerial exposure on the platform top that can be correlated with hardgrounds and or glauconitic horizons within the more basinal locations overlain by deeper water facies the presence of a submarine onlap surface and down slope slide deposits immediately above the sequence boundary suggests that the major transgressive event that followed sequence boundary development was brought about by local extensional tectonic activity the small scale cyclicity within the sequences and the major falls in sea level that produced the sequence boundaries are interpreted to have resulted largely from eustatic processes probably with tectonic enhancement

late cenozoic tectonics of the northwestern san bernardino mountains southern california the late cenozoic structural and stratigraphic history of the northwestern san bernardino mountains supports two distinct episodes of uplift in late miocene to earliest pliocene and quaternary time that we hypothesize are related to movements on low angle structures beneath the range in this paper we document the nature distribution and timing of late cenozoic deformation and deposition in the northwestern san bernardino mountains and we illustrate the neotectonic evolution of the area in a series of interpretive paleotectonic block diagrams in the first episode of deformation late miocene to earliest pliocene motion on the south southwest directed squaw peak thrust system disrupted drainage in pre existing miocene nonmarine basins and uplifted the western third of the present range to form the ancestral san bernardino mountains crystalline rocks of the san bernardino mountains were thrust southward across the present site of the san andreas fault between 9 5 and 4 1 ma at a time when the san gabriel fault was the active strand of the san andreas transform system we speculate that the liebre mountain crystalline block at the northern margin of the ridge basin may be the missing upper plate of the squaw peak thrust now offset along the san andreas fault the second episode of deformation began with uplift of the northern plateau of the modern san bernardino mountains on north directed range front thrusts in early pleistocene time between 2 0 and 1 5 ma synchronous uplift of the northern plateau recorded in early pleistocene fanglomerates on the northwestern margin of the range is interpreted to be the result of movement of a relatively coherent crustal block northward up a south dipping detachment ramp beneath the central range in middle pleistocene time activity on the northern range front began to wane and the locus of uplift shifted to a narrow zone of arching and northward tilting adjacent to the san andreas fault which subsequently migrated rapidly northwestward along the san andreas fault from the western san bernardino mountains into the northeastern san gabriel mountains we attribute this pattern of deformation to the passage of a bulge or strike slip ramp attached to the southwest side of the san andreas fault at depth

on the historical origins of the cej dp2 and ddyn current systems and their roles in the predictions of ionospheric responses to geomagnetic storms at equatorial latitudes in this short letter we recall the differences between the counter electrojet cej which is a phenomenon observed on the magnetically quiet days and the disturbance dynamo ddyn which can be observed during and after a geomagnetic storm the cej is well known to occur near the geomagnetic dip equator it can be identified by a reversal in the horizontal component h of the geomagnetic field daily regular variations in contrast to equatorial electrojet eej that flows eastward in the daytime the cej is considered to flow westward the magnetic signatures of the reversed solar quiet sq current at the low latitude during magnetic storms are due to the ddyn this disturbance ddyn is produced by current systems that are driven by thermospheric storm winds originating from the joule heating of enhanced high latitude currents the dp2 is the magnetic effect of current systems at high latitudes these currents are associated with the coupling of magnetosphere and ionosphere through geomagnetic field lines they are associated to the magnetospheric convection during intense magnetic storms these high latitude currents are enhanced and their magnetic effects can extend toward the low latitudes this work shows that the study of magnetic perturbations makes it possible to understand the disturbances of the ionospheric electric currents the use of an efficient treatment of the magnetic signals makes it possible to separate the magnetic effects of the different perturbations prompt penetration of the magnetospheric convection electric field and disturbance dynamo electric field this was performed in the paper nava et al 2016

platform margins reef facies and microbial carbonates a comparison of devonian reef complexes in the canning basin western australia and the guilin region south china devonian reef complexes were well developed in western australia and south china but no detailed direct comparison has been made between reef building in the two regions the regions differ in several respects including tectonic stratigraphic and palaeoceanographic palaeogeographic settings and the reef building styles reflect minor differences in reef builders and reef facies similarities and differences between the two reef complexes provide insights into the characteristics of platform margins reef facies and microbial carbonates of both regions here we present a comparison of platform margin types from different stratigraphic positions in the late devonian reef complex of the canning basin western australia and middle and late devonian margin to marginal slope successions in guilin south china comparisons are integrated into a review of the reefal stratigraphy of both regions reef facies reef complex architecture temporal reef builder associations 2nd order stratigraphy and platform cyclicity in the two regions were generally similar where the successions overlap temporally however carbonate deposition began earlier in south china carbonate complexes were also more widespread in south china and represent a thicker succession overall platforms in the canning basin grew directly on precambrian crystalline basement or early palaeozoic sedimentary rocks but in south china carbonate complexes developed conformably on older devonian siliciclastic strata pre frasnian reef facies in south china had more abundant skeletal frameworks than in canning basin reefs of equivalent age and famennian shoaling margins containing various microbial reefs may have been more common and probably more diverse in south china however late devonian platform margin types have been documented more completely in the canning basin deep intra platform troughs deep depressions containing non carbonate pelagic sediments nandan type successions that developed along syndepositional faults characterize devonian carbonate platforms in south china but have no equivalent on the lennard shelf canning basin where inter reef areas were more shallow the south china platform to depression pattern was generally continuous from the lower to upper devonian indicating that many pre devonian tectonic features continued to exercise considerable effect through deposition localized fault controlled subsidence was an important factor in both regions but similarities in 2nd order aggradation progradation cycles suggest that eustasy was also an important control on the larger scale stratigraphic development of both regions

chromium isotope systematics in the connecticut river abstract limited constraints on cr isotope fractionation during weathering and river transport is currently a gap in our understanding of the chromium cr isotope system which is an emerging proxy in environmental and paleoenvironmental studies here we investigate cr mobility and isotope fractionation from the temperate connecticut river usa including cr concentrations and isotopic compositions of river water suspended particles riverbed sediments and weathering profiles the 53cr values of the connecticut river water range from 0 17 to 0 92 which are similar to or higher than the weathered rocks in the catchment 0 08 to 0 29 we find seasonal variations in dissolved 53cr values in some but not all tributaries suggesting that dissolved 53cr is not a simple function of seasonality but may also be influenced by sub catchment heterogeneity in lithology in contrast to dissolved cr we found consistent seasonal difference in suspended cr concentration and 53cr suspended 53cr is 0 1 higher than the unfractionated bse in the fall 0 01 0 13 but indistinguishable from the bse in the spring 0 11 to 0 00 the suspended cr concentration is also lower in the spring and with higher al mn fe concentrations the lower suspended cr concentration and 53cr in spring may be linked to increased silicate and oxide load with depleted cr due to stronger hydrological flux building from our dataset there is not a consistent correlation with climate zones in a compilation of 53cr and cr concentration data from river water and weathering profiles suggesting that climate is not a dominating factor controlling cr isotopic behavior during weathering suggesting that other factors e g local catchment conditions and dissolved organic matter may also be responsible for the observed river water 53cr variability

equatorial disturbance dynamo electric fields f region vertical drift data from jicamarca peru show that equatorial east west electric fields are sometimes perturbed 16 24 hours after the onset of geomagnetic storms these disturbance dynamo electric fields which must be caused primarily by the action of neutral winds at low and middle latitudes decrease and sometimes even reverse the quiet time electric field pattern during both daytime and nighttime the long delay excludes the possibility that gravity waves are responsible and suggests that the thermospheric circulation is disturbed the data also show that after some storms there are no such delayed disturbances a fact which may be due to the longitudinal structure of the disturbances at high latitudes and or that only very strong storms can produce major thermospheric perturbations that extend to middle and low latitudes

ionospheric redistribution during geomagnetic storms 1 the abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms recent reports suggest that the magnitude of the plasma density enhancement depends on the ut of storm onset this possibility is investigated over a 7year period using global maps of ionospheric total electron content tec produced at the jet propulsion laboratory the analysis confirms that the american sector exhibits on average larger storm time enhancement in ionospheric plasma content up to 50 in the afternoon middle latitude region and 30 in the vicinity of the high latitude auroral cusp with largest effect in the southern hemisphere we investigate whether this effect is related to the magnitude of the causative magnetic storms using the same advanced dst index employed to sort the tec maps into quiet and active dst 100 nt sets we find variation in storm strength that corresponds closely to the tec variation but follows it by 3 6h for this and other reasons detailed in this report we conclude that the ut dependent peak in storm time tec is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the south american region the large dst variation suggests a possible system level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current possibly connected through ut dependent modulation of ion outflow

a middle ordovician drowning unconformity on the northeastern flank of the okcheon ogcheon belt south korea abstract the maggol limestone of ordovician age was deposited in the taebaeksan taebacksan basin which occupies the northeastern flank of the okcheon ogcheon belt of south korea carbonate facies analysis in conjunction with conodont biostratigraphy suggests that an overall regression toward the top of the maggol limestone probably culminated in subaerial exposure of platform carbonates in the early middle ordovician earliest darriwilian elsewhere this subaerial exposure event is manifested as a major paleokarst unconformity at the sauk tippecanoe sequence boundary beneath the middle ordovician succession and its equivalents most in notably north america and north china due to its global extent this paleokarst unconformity has been viewed as a product of second or third order eustatic sea level fall during the early middle ordovician the sauk tippecanoe sequence boundary in south korea however appears to be a discrete marine flooding surface in the upper maggol limestone strata beneath this surface represent by a thinning upward stack of exposure capped tidal flat dominated cycles that are closely associated with multiple occurrences of paleokarst related solution collapse breccias this marine flooding surface is onlapped by a thick succession of thin bedded micritic limestone that is eventually overlain by a middle ordovician condensed section this physical stratigraphic relationship suggest that second and third order eustatic sea level fall may have been significantly tempered by regional tectonic subsidence near the end of maggol deposition the tectonic subsidence is also evidenced by the occurrence of coeval off platform lowstand siliciclastic quartzite lenses as well as debris flow carbonate breccias i e the yemi breccia in the basin with continued tectonic subsidence a subsequent rise in the eustatic cycle caused drowning and deep flooding of the carbonate platform forming a discrete marine flooding surface that may be referred to as a drowning unconformity this tectonic interpretation contrasts notably with the slowly subsiding carbonate platform model for the basin as has been previously suggested thus it is proposed that the taebaeksan basin in the northeastern flank on the okcheon belt evolved from a slowly subsiding carbonate platform to a rapidly subsiding intracontinental rift basin during the early middle ordovician

extending comprehensive models of the earth s magnetic field with orsted and champ data summary a new model of the quiet time near earth magnetic field has been derived using a comprehensive approach which includes not only pogo and magsat satellite data but also data from the orsted and champ satellites the resulting model shows great improvement over its predecessors in terms of completeness of sources time span and noise reduction in parameters with its well separated fields and extended time domain of 1960 to mid 2002 the model is able to detect the known sequence of geomagnetic jerks within this frame and gives evidence for an event of interest around 1997 because all sources are coestimated in a comprehensive approach intriguing north south features typically filtered out with other methods are being discovered in the lithospheric representation of the model such as the s atlantic spreading ridge and andean subduction zone lineations in addition this lithospheric field exhibits significantly less noise than previous models as a result of improved data selection the f region currents through which the satellites pass are now treated as lying within meridional planes as opposed to being purely radial results are consistent with those found previously for magsat but an analysis at orsted altitude shows exciting evidence that the meridional currents associated with the equatorial electrojet likely close beneath the satellite besides the model a new analysis technique has been developed to infer the portion of a model parameter state resolved by a particular data subset this has proven very useful in diagnosing the cause of peculiar artefacts in the magsat vector data which seem to suggest the presence of a small misalignment bias in the vector magnetometer

impact of oscillating imf bz during 17 march 2013 storm on the distribution of plasma over indian low latitude and mid latitude ionospheric regions we show evidence of a positive ionospheric storm occurring simultaneously at the equatorial low and mid latitude ionospheric regions in the indian sector in response to an intense geomagnetic storm on 17 march 2013 the storm had its onset time coinciding with the local noon an on site digisonde at trivandrum dip equator recorded a sharp decrease in the height of f region peak in the afternoon which is a signature of westward electric field associated with a cej coupled with it was a simultaneous increase in tec in the entire indian region the magnitude of increase in tec decreased slowly northward of the dip equator and had almost no change near the anomaly crest further northward of the anomaly crest the tec started increasing again and at shimla a mid latitude station it had a value close to 2 times its monthly mean we surmise that the westward electric field resulting from the cej pushed the f layer at the dip equator down to the altitude regions where recombination and diffusion played minimal roles no loss of plasma due to diffusion while photo production of ions was still taking place led to an enhancement in the electron density near the equatorial low latitude region the joule heating of the thermosphere on the other hand gave rise to the tads which pushed the plasma up in altitude at the equatorial anomaly region it supplemented the loss of plasma at the anomaly crest region resulting in no change in the tec and a marked increase in the tec in the mid latitude ionosphere

equatorial disturbance dynamo electric field longitudinal structure and spread f a case study from guar eits campaigns digisondes ionosondes an hf doppler radar and magnetometers were operated in brazil and india during the september october 1994 guara eits campaigns analysis of the data for the two disturbed intervals 2 4 october and 25 27 september provided evidence of a longitudinal structure in the disturbance dynamo dd electric field at low latitudes the dd electric field which is westward in the evening inhibited the developments of the equatorial prereversal electric field and postsunset esf whereas the simultaneous eastward field in the predawn sector did not lead to esf contrary to what is normally expected this nondevelopment of esf is suggested as evidence of the stabilizing effect of transequatorial neutral winds associated with stormtime circulation the campaign observations clearly demonstrate that the dd electric fields could often mask the low latitude ionospheric responses to prompt penetration electric fields in the course of sustained substorm activity

lithofacies and sequence development on an upper devonian mixed carbonate siliciclastic fore reef slope canning basin western australia detailed sedimentological and stratigraphical analysis coupled with conodont biostratigraphy of a fore reef slope succession in the napier range napier formation is used to develop a depositional model and relative sea level history for late frasnian to late famennian reef evolution in the canning basin of north western australia changes in sedimentary style on the slope reflecting differing rates of carbonate production on the platform are linked to third and higher order relative sea level fluctuations overlapping slope aprons accumulated along the base of a steep walled platform margin coarse carbonate debris was deposited adjacent to the margin as talus breccias via rockfall and debris flow breccias depositional slopes up to 45 and locally steeper are demonstrated using rotated geopetal cavity fills the predominance of channel filling lithofacies throughout the slope succession indicates the highly channelized nature of the aprons the middle slope is dominated by sandy oolitic peloidal turbiditic grainstones interpreted as sediment exported from an active platform the turbidites and associated debris flow breccias contrast with condensed carbonate intervals and deep water non fenestral stromatolites that record times of very low platform production lower slope turbidites and associated intraclastic breccias indicate widespread redeposition of sediment eroded from lithified and semi lithified limestones higher up the slope several third order sequences are recognized in the fore reef succession and these are composed primarily of transgressive and highstand deposits carbonate production was severely restricted in the early famennian coinciding with development of onlapping siliciclastic aprons during a relative sea level lowstand evidence for a subaerial exposure event is also preserved within the siliciclastic strata controls on sequence development are difficult to constrain although two sequence boundaries can be correlated with falls on the global sea level curve the reef complexes evolved in an active extensional regime and it is highly likely that tectonism in conjunction with eustasy controlled accommodation on the platform and therefore carbonate productivity

delta chromium 53 52 isotopic composition of native and contaminated groundwater mojave desert usa abstract chromium vi concentrations in groundwater sampled from three contaminant plumes in aquifers in the mojave desert near hinkley topock and el mirage california usa were as high as 2600 5800 and 330 g l respectively 53 52cr compositions from more than 50 samples collected within these plumes ranged from near 0 to almost 4 near the plume margins assuming only reductive fractionation of cr vi to cr iii within the plume apparent fractionation factors for 53 52cr isotopes ranged from eapp 0 3 to 0 4 within the hinkley and topock plumes respectively and only the el mirage plume had a fractionation factor similar to the laboratory derived value of e 3 5 one possible explanation for the difference between field and laboratory fractionation factors at the hinkley and topock sites is localized reductive fractionation of cr vi to cr iii with subsequent advective mixing of native and contaminated water near the plume margin chromium vi concentrations and 53 52cr isotopic compositions did not uniquely define the source of cr near the plume margin or the extent of reductive fractionation within the plume however cr vi and 53 52cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of cr contamination plumes reductive fractionation of cr vi predominates in plumes having higher eapp these plumes may be suitable for monitored natural attenuation in contrast advective mixing predominates in plumes having lower eapp the highly dispersed margins of these plumes may be difficult to define and manage