sedimentology and isotope geochemistry of carnian deep water marl limestone deposits from the sicani mountains sicily environmental implications and evidence for a planktonic source of lime mud abstract the upper triassic halobia bearing marl limestone deposits from the sicani mountains sicily record the sedimentary evolution of the sicanian basin through the middle and late carnian time dark marls and interbedded grey calcilutites of julian age are characterized by abundant pyrite sparse bioturbation and negative carbonate carbon 13c values they accumulated in a basin with dominantly anoxic to dysaerobic bottom waters lower tuvalian dark grey pyritic marls and calcilutites which contain carbonate minerals with relatively high mn contents and widely fluctuating 13c signatures were deposited under dysaerobic conditions middle and upper tuvalian cherty limestones show intense bioturbation and nearly invariable positive 13c values around 2 for calcite they form a thick and monotonous succession accumulated in a deeper and more oxygenated basin the halobia bearing deposits preserve some calcareous nannoplanktonic forms the nannofossils varying in size from 7 to 32 m are significantly abundant in the cherty limestones pointing to a notable role of the calcareous nannoplankton as a source of carbonate mud in the deep water basins of the southern tethys during the late triassic time

facies and sequence controls on the appearance of the cambrian biota in southwestern mongolia implications for the precambrian cambrian boundary neoproterozoic cambrian rocks of the zavkhan basin govi altay western mongolia com prise large scale alternations of siliciclastic and carbonate dominated units cf grand cycles analysis of such dcpositional sequences near the base of the cambrian confirms that the distribution of trace fossils small shelly fossils and calcimicrobial structures was strongly controlled by ecology and taphonomy corre sponding to specific points in a sea level cycle evolution of the cambrian biota is thus viewed through a series of narrow time windows once only for each dcpositional cycle correlation of the precambrian cambrian boundary level on the basis of the first appearance of the phycodes pedum assem blage is also fraught with difficulty since stratigraphic resolution may be limited to a single sea level cycle c 1 5 ma it is suggested that in many cases basin analysis will need to be undertaken before this bound ary can be drawn

the ediacaran cambrian rise of siliceous sponges and development of modern oceanic ecosystems abstract the lack of unequivocal sponge fossils before the cambrian despite their probable deep origin during the cryogenian period has been a conundrum to geologists their impact on the dramatic evolution of ecosystems and the seawater silica cycle during the ediacaran cambrian e c transition is also speculative in this study abundant sponge spicules and spicule like structures that probably represent original sponge fossils were recovered from four sections of the e c boundary interval in the yangtze gorges south china the paleontological and geochemical data presented herein provides evidence for a continuous distribution of relatively abundant sponge spicules some even forming spiculites as well as the earliest biogenic deposition of silica by metazoans in the ediacaran cambrian boundary interval these results further confirm that a biological takeover of oceanic dissolved si co occurred with the evolution of silica biomineralization in the e c interval resulting in the widespread deposition of biogenic chert hydrothermal input in spicule bearing cherts is also observed such hydrothermal activity might have favored the blooming of sponges through significant nutrient supply these results provide the first conjunction of geochemical and paleontological proxies in support of previous models considering that sponges by ventilation filtration and oxygenation of seawater were important ecosystem engineers of the e c bioradiation event and of the related establishment of modern type ecosystems

geochemistry genesis and health implications of fluoriferous groundwaters in the upper regions of ghana the most appropriate and widely used source of drinking water for the populations of the upper regions of ghana is groundwater in general groundwater quality is acceptable except for some parts of the bolgatanga and bongo districts where there are occurrences of elevated levels of natural groundwater fluoride concentrations of groundwater fluoride in excess of the world health organization who maximum guideline value 1 5 mg l in the bongo area have been known since 1978 however the effect of fluoride on people ingesting the water did not receive public and medical attention until october 1993 when health personnel were asked to investigate the cause of stained teeth in school children the investigation established that 62 of the total population of school children in the bongo area had dental fluorosis against this background a study was initiated to understand the geochemistry genesis and distribution of fluoride in relation to the geology of the area groundwater fluoride in the upper regions ranges from 0 11 to 4 60 ppm with the highest concentrations associated with the fluorine enriched bongo coarse grained hornblende granite and syenite suite the source of groundwater fluoride within the bongo granitoids is dissolution of the mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products applying the who recommended guideline values for fluoride in drinking water reveals that 49 of wells in the area deliver water below the optimum level of 0 5 mg l f these populations are thus prone to dental caries twenty eight percent of the wells fall within the optimum interval for good dental health 0 5 1 5 mg l f twenty three percent of the wells have concentrations above the recommended maximum guideline limit of 1 5 mg l f this population is susceptible to dental and possibly skeletal fluorosis climatic conditions of the area suggest that the individual water consumption is in the order of 3 to 4 l which is higher than the who estimate of 2 l adult day in addition dietary intake for the upper region population is probably higher than who baseline values 0 2 0 5 mg day this implies that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected geochemical symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education programs in the region by casting fluoride data into contoured geochemical health risk maps using intake interval guidelines more closely aligned to regional climatic and dietary conditions health officals can better judge the impacts regional and population based of fluoride on segments of the population such as various sex and age groups

martin brasier s contribution to the palaeobiology of the ediacaran cambrian transition martin brasier s work spanned almost the entire geological column but the origin of animals and the nature of the cambrian explosion were areas of particular interest to him martin adopted a holistic approach to the study of these topics that considered the interplay between multiple geological and biological phenomena and he sought to interpret the fossil record within the broad context of geological biogeochemical and ecological changes in the earth system here we summarize martin s main contributions to this area of research and assess the impact of his findings on the development of this field karl popper would have said that palaeontology is not real science because you can t go out and sample it i think absolutely the opposite i think this is actually where science is it s trying to guess what lies over the hill and map terra incognita when people come in and colonize that s just technology martin brasier 2013 excerpt from a phone interview in moor 2016

main features of hydrogeodynamic earthquake precursors abstract an analysis of available data on hydrogeodynamic precursors of large earthquakes in different regions of the world is presented these precursors were registered by variations of groundwater level before 31 earthquakes with magnitudes between 4 5 and 8 0 we investigated some features of the precursors such as the signal amplitude shape and time as well as some precursor indices as functions of magnitude and epicentral distance in most cases groundwater level variations before earthquakes have extreme values a new index the precursor extremum time has been defined for such precursors it has been found that this index as well as the amplitude of groundwater level variations correlates well with precursor time the hydrogeodynamic precursor time and signal amplitude do not show sufficiently close correlative relationships with earthquake magnitude and epicentral distance at the same time there is a trend of increasing precursor time and amplitude with the growth of earthquake magnitude and an inversed relationship for epicentral distance these properties of hydrogeodynamic precursors seem to be associated with geodynamic processes developing in an extensive area during the preparation of a large earthquake manifestations of these precursors also depend on the tensosensitivity of the borehole aquifer system which controls the transformation of strain into the hydrogeodynamic precursory response

stable isotopic calibration of the earliest skeletal fossil assemblages in eastern siberia precambrian cambrian boundary sections from the eastern margin of the siberian platform provide important reference sections for stable isotopic correlation of the newly defined precambrian cambrian boundary level since they contain some of the earliest pre tommotian shelly fossil assemblages known and are amenable to 13 c stratigraphy stable isotopes are examined from the dvortsy and ulakhan sulugur sections river aldan where sparse pre tommotian assemblages occur and from the uchur river region where the putative anabarites trisulcatus and purella antiqua zones of the nemakit daldynian stage are well developed diagenetic resetting of 18 o and 13 c must be taken into account when comparing such sections simple corrections allow for stable isotopic correlation of basal nemakit daldynian and tommotian strata across eastern siberia

reconstructing the avalonia palaeocontinent in the cambrian a 519 ma caliche in south wales and transcontinental middle terreneuvian sandstones an early cambrian caliche on the st non9s formation emended is the base of the caerfai bay formation unit term changed at caerfai bay south wales subaerial exposure and the caliche mean the two formations were not genetically related units the st non9s is an older sand sheet likely tidalitic not delta related referred to avalonian depositional sequence ads 2 and the caerfai bay is a shallow mud basin unit refered to ads 4a the similar random formation upper ads 2 in north american avalonia has a basal age of c 528 ma and is unconformably overlain by red mudstones or sandstones in fault bounded basins on the avalonian inner platform coeval british sandstones lower hartshill wrekin st non9s brand hills are unconformably overlain by latest terreneuvian ads 3 or epoch 2 ads 4a units dates of 519 ma on caerfai bay ashes give an upper bracket on the late appearance of avalonian trilobites and suggest an ads 2 4a hiatus of several million years post st non9s and post random basin reorganization led to abundant caerfai bay formation volcanic ashes and sparse brigus formation ashes in newfoundland the broad extent of erosional sequence boundaries that bracket lithologically similar to identical units emphasize that east and west avalonia formed one palaeocontinent the inner platform in southern britain was larger than the midlands craton a tectonically defined later palaeozoic area unrelated to terminal ediacaran early palaeozoic depositional belts the cool water successions of early palaeozoic avalonia were distant from coeval west gondwanan carbonate platforms

how old is the tommotian shelly faunas and phytoplankton from lower cambrian tommotian strata within and outside the type area in siberia indicate that the tommotian stage is younger than previously believed deposits referred to the tommotian stage in siberia are in part time equivalent to the talsy lukati horizon in the east european platform which has yielded trilobites and is correlated with the schmidtiellus mickwitzi trilobite zone in baltoscandia published micropaleontological data seem to indicate that the yudomian stage preceding the tommotian may also belong to the cambrian system the demonstrated contemporaneity of tommotian small shelly faunas with the trilobites could result in a revision of models dealing with the early radiation of metazoan phyla speciation and skeletonization

early cambrian chronostratigraphy and geochronology of south australia abstract the most successful chronostratigraphic correlation methods enlist multiple proxies such as biostratigraphy and chemostratigraphy to constrain the timing of globally important bio and geo events here we present the first regional high resolution shelly fossil biostratigraphy integrated with 13c chemostratigraphy and corresponding 18o data from the traditional lower cambrian terreneuvian and provisional cambrian series 2 of south australia the global zhuce shice positive excursions ii and iii and the care are captured in lower cambrian successions from the arrowie and stansbury basins the south australian shelly fossil biostratigraphy has a consistent relationship with the 13c results bolstering interpretation identification and correlation of the excursions positive excursion ii straddles the boundary between the kulparina rostrata and micrina etheridgei zones and the care straddles the boundary between the m etheridgei and dailyatia odyssei zones peaking in the lower parts of the latter zone new ca tims zircon dates from the upper hawker group and billy creek formation provide geochronologic calibration points for the upper d odyssei zone and corresponding chemostratigraphic curve embedding the lower cambrian successions from south australia into a global chronostratigraphic context this multi proxy investigation demonstrates the power of integrated methods for developing regional biostratigraphic schemes and facilitating robust global correlation of lower cambrian successions from south australia part of east gondwana with coeval terranes on other cambrian palaeocontinents including south and north china siberia laurentia avalonia and west gondwana

effects of bioturbation on carbon and sulfur cycling across the ediacaran cambrian transition at the gssp in newfoundland canada the initiation of widespread penetrative bioturbation in the earliest phanerozoic is regarded as such a significant geobiological event that the boundary between ediacaran and cambrian strata is de

cephalopod ancestry and ecology of the hyolith allatheca degeeri s l in the cambrian evolutionary radiation abstract pyritized elongate conical conchs of allatheca degeeri s l are common in dysoxic dark gray mudstone intervals in the early cambrian upper terreneuvian series 2 boundary interval cuslett formation at keels eastern newfoundland wave oriented horizontal specimens are most abundant in this cool water high latitude off shore shelf facies of the early palaeozoic avalon microcontinent based on conch morphology shell microstructure and the operculum the species is an orthothecid hyolith comparison with the sizes of the early shells of planktic gastropods indicates a non planktic life mode of a degeeri s l hatchlings although buoyancy calculations show that small juveniles with septate conchs to ca 17 mm long could have been nektic planktic if smaller a degeeri s l individuals had a non benthic mode of life they and pseudoconodonts were the oldest skeletalized pelagic nektic animals in the cambrian evolutionary radiation most a degeeri s l conchs at keels are horizontally embedded and show a bimodal wave determined orientation but about 10 of the large conchs are vertically embedded with their aperture down as larger shells were not neutrally buoyant the vertical orientations of about 10 of the conchs suggests an infaunal likely detritivore life mode suggestive of a scaphopod available morphologic and taphonomic evidence suggests that the vertically embedded conchs are in situ remains of dead benthic animals that colonized the bottom in better oxygenated intervals based on the current knowledge of early palaeozoic hyolith and cephalopod larval and adult morphologies existing hypotheses of a planktic origin of cephalopods from hyolith ancestors are evaluated and no evidence for such an evolutionary relationship is concluded to exist

carbon isotopic profile across the bilara group rocks of trans aravalli marwar supergroup in western india implications for neoproterozoic cambrian transition abstract the rocks of marwar supergroup in the trans aravalli sector in western india are presumed to span the time interval between neoproterozoic and early cambrian this predominantly unfossiliferous marine sedimentary sequence is characterized by a lower arenaceous facies jodhpur group middle carbonate facies bilara group and upper argillaceous arenaceous facies nagaur group rocks the sedimentation has been essentially in a shallow basin described either as the fore land slope of the rising aravalli mountains or a sag basin which developed and evolved due to subsidence of the updomed crust during neoproterozoic malani magmatism that failed to open rifts the carbon isotopic profile for the bilara group carbonate rocks in the lower part shows marked oscillations and broadly negative 13 c character with negative anomalies as low as pdb observed near the base of dhanapa formation lower unit and pdb in the overlying gotan formation middle unit the upper part of the profile shows a gradual positive shift the carbon isotopic signatures of the bilara group rocks can be correlated with the end neoproterozoic early cambrian vendian tommotian carbon isotopic evolution curve extremely low 13 c values indicate the glaciation related cold climatic postulates of the end neoproterozoic followed by the warmer climatic conditions as indicated by the positive shift the carbon isotopic data for gotan formation carbonates at variance with the globally observed 13 c trends for early tertiary do not support the recently proposed tertiary age for the bilara group

fluorine distribution in waters of nalgonda district andhra pradesh india geochemical and hydrochemical studies were conducted in nalgonda district a p to explore the causes of high fluorine in waters causing a widespread incidence of fluorosis in the local population samples of granitic rocks soils stream sediments and waters were analyzed for f and other salient chemical parameters samples from the area of hyderabad city were analyzed for comparison the f content of waters in areas with endemic fluorosis ranges from 0 4 to 20 mg l the low calcium content of rocks and soils and the presence of high levels of sodium bicarbonate in soils and waters are important factors favoring high levels of f in waters

integrated stratigraphic geochemical and paleontological late ediacaran to early cambrian records from southwestern mongolia comment global correlation of sedimentary rock successions requires an integrated approach that uses all fossil based and alternative lithostratigraphic geochemical paleomagnetic geochronologic sequence stratigraphic data e g van couvering and berggren 1977 proposed global correlations and their role in interpreting earth and biotic history require a thorough examination of the utility and temporal resolution allowed by each correlation technique in comparison to the others the article by smith et al 2016 is a welcome contribution to understanding the upper ediacaran lower cambrian succession of the zavkhan terrane in the khasagt khairkhan range of southwestern mongolia their work complements earlier syntheses on the zavkhan terrane completed by soviet mongolian teams e g voronin et al 1982 esakova and zhegallo 1996 and under international geoscience programme igcp project 303 late precambrian cambrian event stratigraphy brasier et al 1996a see associated papers in geological magazine v 133 no 4

occurrence and hydrogeochemistry of fluoride in alluvial aquifer of weihe river china fluoride f has significant impacts on human health high fluoride groundwater up to 1 90 mg l has been found in upper confined aquifer underlying the first terrace of weihe river during a hydrogeological investigation for water supply in 2005 to reveal the occurrence and hydrogeochemistry of high f groundwater hydrogeochemical tools such as saturation index ionic ratios and correlation analysis were used in this study the study shows that the concentrations of most physiochemical parameters from phreatic water influenced by intensive evaporation and anthropogenic activities such as unregulated sewage and excreta disposal and agricultural practices in the area are higher than those of confined water the f concentration in phreatic water is within the acceptable limits set by china and the world health organization who while that of upper confined water shows a decreasing trend northwestward as the weihe river approaches with f concentration in the first terrace beyond the national and the who standards high f groundwater is observed in alkaline environment associated with high na ph hco3 and low ca2 and mg2 the enrichment of f is controlled by geologic and hydrogeological conditions fluorine bearing minerals presented in alluvial formations and their dissolution precipitation under the alkaline environment along groundwater flow ion exchange human activities and the mixing of different recharge waters may influence the enrichment of f as well

oxygen and carbon isotope stratigraphy of the palaeogene and cretaceous limestones in the bottaccione gorge and the contessa highway sections umbria italy we have made oxygen and carbon isotope measurements on limestone samples of albian to eocene age recovered from the bottaccione gorge section in the umbrian apennines central italy additional measurements have been made on topmost maastrichtian and palaeocene sediments from the adjacent contessa highway section our data from the bottaccione gorge show 13c maxima at the cenomanian turonian boundary and during the palaeocene as well as a pronounced 13c minimum 7 metres above the clay layer at the k t boundary our data from the contessa highway show a 13c minimum 9 metres above the k t boundary clay these minima are probably diagenetic artifacts in the bottaccione gorge there is evidence for a hiatus in the early middle eocene the palaeocene of the bottaccione gorge appears to have been affected by slumping or faulting in addition to the diagenetic overprinting giving a spurious 13c recovery after the k t boundary the contessa highway section appears to be more complete the coniacian maastrictian is characterized by relatively stable 13c values our data indicate an increase in 18o and therefore possible cooling across the cretaceous tertiary boundary in both the bottaccione and contessa highway sections

fluoride incidence in groundwater in an area of peninsular india groundwater samples were collected from anantapur district andhra pradesh india the district is mainly underlain by peninsular gneisses of archaean age the samples were analysed for fluoride f along with other chemical parameters the results suggest that the main sources of f in groundwater in the district are the country rocks in which fluorine is strongly absorbed in soils consisting of clay minerals a strong positive correlation between f and lithogenic sodium reflects weathering activity this is responsible for the leaching of f which is also caused by the semi arid climate and intensive irrigation in the area an alkaline environment of circulating water in the investigated area mainly facilitates leaching of f from the soils contributing to high f containing groundwater a longer residence time of water in the aquifer zone caused by a high rate of evapotranspiration and a weathered zone of low hydraulic conductivity which promotes the dissolution of fluorine bearing minerals is another factor that further increases the f content in groundwater suggestions are made to improve groundwater quality and thus the health status of the population

the succession of small shelly fossils especially conoidal microfossils from english precambrian cambrian boundary beds small shelly fossils especially conoidal microfossils have potential for biostratigraphic correlation of precambrian cambrian boundary rocks where evolutionary successions of taxa can be recognized a succession of hyoliths brachiopods and species of sunnaginia torellella eccentrotheca and rhombocorniculum can be recognized in the home farm member of nuneaton and or the comley limestone of shropshire england revised ranges of taxa are given and sunnaginia neoimbricata n sp s parva n sp s angulata n sp eccentrotheca grandis n sp and several new records are described from nuneaton and comley the similarity in the sequence of small shelly fossils in england and siberia indicates that a correlation can be achieved between the two areas it is suggested that the lower tommotian to lower atdabanian correlates with the hartshill formation of nuneaton of which the condensed home farm member spans the mid tommotian to lowest atdabanian while the upper atdabanian to lower botomian correlates with the condensed comley limestone of shropshire

latest precambrian to early cambrian basin evolution fortune bay newfoundland fault bounded basin to platform uppermost precambrian and lowest cambrian sediments of the rencontre chapel island and random formations in the fortune bay area western avalon zone consist of conglomerates sandstones and shales deposited in fluvial marginal marine and open marine settings deposition began in a small fault bounded basin alternation between nonmarine and marine deposition resulted from pulses in fault activity uplift and coarse terrestrial clastics separated by quiescent periods of basinwide thermal subsidence transgressive fine grained marine units overstepping earlier basin margins the tectonic regime may have been extensional rift or transtensional strike slip pull apart a strike slip origin is easiest to defend and is consistent with current tectonic models for the avalon zone involving prolonged extension or transtension but little spreading the fortune bay basin persisted until the beginning of the cambrian period at which time eustatic sea level rise led to widespread transgression and d

nutrient enriched waters and the early skeletal fossil record this paper examines the role of stratified oxygen depleted and nutrient enriched water masses new in transforming the fossil record over the precambrian cambrian boundary interval the following may serve as markers for the encroachment of new over low latitude cratons trace element enriched black shales stone coals and hydrocarbon source rocks phosphorites phosphatized shells and organic matter sponge spicule cherts early appearance of silica and phosphatic skeletons appearance of anabarites and coleoloides biofacies peak diversity of phosphatic species occurrence of black shale lagerstatten and light 13 c values of carbonates nutrient depleted waters ndw are inferred over inner cratonic areas and nutrient starved waters nsw may well have developed over deeper waters at times through the later cambrian related to the effects of sea level rise and salinity stratification carbon isotopic fluctuations are suggested to record the history of these water masses with major changes in carbon burial and palaeoproductivity the latter may well imply episodes of greenhouse climate with globally raised levels of carbon dioxide and relatively high ocean temperatures

a refined chronology for the cambrian succession of southern britain abstract three dated u pb zircon ash beds from biostratigraphically constrained avalonian successions of shropshire england and pembrokeshire wales delimit the traditional lower9 middle9 cambrian boundary and resolve a problematic regional correlation in shropshire a date of 514 45 0 36 0 81 including tracer calibration and 238 u decay constant errors ma from near the top of the lower comley sandstone formation provides a maximum age for the boundary between cambrian stages 3 and 4 and a date of 509 10 0 22 0 77 including tracer calibration and 238 u decay constant errors ma from the basal quarry ridge grits upper comley sandstone formation provides a minimum age for the boundary between cambrian stages 4 and 5 and thus series 2 and 3 these dates offer a calibration of early metazoan evolution by directly constraining the age of the intervening comley limestones which contain diverse small shelly fossils in addition to trilobites and also a key early occurrence of exceptional three dimensionally preserved arthropods in pembrokeshire an ash bed from the caerfai bay shales formation dates to 519 30 0 23 0 77 including tracer calibration and 238 u decay constant errors ma equivalent to a horizon low in the lower comley sandstone formation of shropshire possibly around the level at which trilobites make their first local appearance supplementary material appendix 1 a table of isotope data is available at http www geolsoc org uk sup18444

hydrochemical characterization of drinking groundwater with special reference to fluoride in an arid area of china and the control of aquifer leakage on its concentrations the objective of the study is to determine the distribution and origin of fluoride in two confined aquifers within the depth of 80 240 m mid deep confined aquifers in shizuishan city an arid area in northwest china based on geological and hydrogeological conditions the distribution patterns of fluoride in the two confined aquifers were studied correlation analysis was used to reveal the mechanisms and reactions influencing the groundwater chemistry the control of aquifer leakage induced by intense groundwater abstraction on fluoride concentrations was also discussed the results show that the concentration of f in some locations of the study area is beyond the limit of the standards for drinking water quality of china correlation analysis shows that the major reactions occurring in the confined aquifers are dissolution of gypsum fluorite and halite and precipitation of calcite and dolomite groundwater leakage from shallow aquifers is also responsible for the elevation of fluoride in mid deep confined aquifers the research is a scientific basis for the rational development and utilization of groundwater in this area and it may be referenced by international scholars for similar research in other parts of the world

carbon oxygen and strontium isotopes in paleozoic carbonate components an evaluation of original seawater chemistry proxies abstract brachiopods trilobites cements and whole rock matrix material were evaluated for their reliability as proxies of original seawater carbon oxygen and strontium isotope chemistry in this process coeval material was evaluated from individual horizons of formations spanning the permian to cambrian unaltered shells of low mg calcite articulated brachiopods retain original seawater oxygen carbon and strontium isotope compositions as old as late ordovician assessments of older specimens are hampered by a lack of suitable material coeval brachiopod whole rock sets a definitive assessment of cement marine chemistry is difficult due to the paucity of material but despite this caveat cements hold some promise for retaining original carbon and possibly strontium isotope seawater values in contrast the potential of whole rock material as a proxy of original seawater chemistry is quite complex in some but not all instances the carbon isotopic composition of whole rock after detailed scrutiny and evaluation appears to represent an original seawater chemistry signal in a few instances their oxygen isotope compositions reflect original seawater values unlike the stable isotope compositions the strontium isotopes of all studied whole rock material permian to upper cambrian appear not to reflect original seawater chemistry values thus the potential for retaining original seawater isotope chemistry and serving as specific proxies in order of decreasing reliability are 1 unaltered low mg calcite brachiopods c o and sr isotopes 2 pristine marine cements c and sr isotopes and 3 whole rock material c isotopes carbon oxygen and strontium isotope compositions of ordovician trilobites mirror those of coeval unaltered brachiopods cambrian trilobites hold significant promise as an important proxy of original seawater isotope chemistry but further studies are needed to ascertain their full potential the survey of isotopes in some ordovician and cambrian intermediate low mg calcite trilobites demonstrates their potential as an important proxy of original seawater chemistry

the problems and potential of using animal fossils and trace fossils in terminal proterozoic biostratigraphy abstract despite the discovery of soft bodied megascopic fossils of late neoproterozoic age at numerous localities world wide there has been slow acceptance of their potential for intercontinental correlation the stratigraphic thickness of sediments separating individual occurrences of such fossils from the base of the cambrian is very varied basic questions have also been posed as to the classification of the organisms represented and hence their likely time significance recent geochronological studies support notions of a narrow time distribution well studied neoproterozoic sequences in eurasia eastern and western north america and southern australia show strikingly similar patterns of increase in the numbers and diversity of trace fossils and soft bodied megascopic remains up section though strata immediately preceding the cambrian are relatively barren other than for a sparse palynoflora and compressions of primitive plants trace fossils from australian sections relating to an early part of the ediacaran apparently overlap a time of abundance of large process bearing acritarchs and big leiosphaerids this overlap of early animal traces and distinctive acritarchs may prove to be of significant biostratigraphic importance rare discoveries of forms resembling rangea gurich in the flinders ranges of south australia precede the classical ediacara assemblage and may provide a possible correlation with occurrences of this genus in namibia the distinctive remains and trace fossils at this level constituting the rangeid hiemalora assemblage zone resemble a biota from the podolia region of the ukraine and show a similarity to finds in parts of the windermere supergroup of the northwest territories canada similarly the offshore frondose assemblage of newfoundland is comparable with the biota of charnwood forest england the type ediacara assemblage of the flinders ranges characterizing the dickinsonia costata assemblage zone is a climax biota with diverse taxa and large individual species as well as some 20 ichnogenera it closely correlates with a late redkinian or early kotlinian assemblage in the upper part of the section on the zimny gory coast of the white sea northern russia the trace fossils of these levels show that significant diversification began before the cambrian

fluoride contamination of groundwater in parts of eastern india and a preliminary experimental study of fluoride adsorption by natural haematite iron ore and synthetic magnetite incidence of high fluoride f in groundwater 1 5 mg l in two tribal belts of eastern india one around chukru in the palamau district of jharkhand and the other around karlakot in the nuapada district of odisha has been studied the maximum concentration of f in groundwater from dug wells and tube wells is 10 30 mg l in chukru and 4 62 mg l in karlakot the groundwaters are mildly alkaline with ph ranges of 7 52 8 22 and 7 33 8 20 in chukru and karlakot respectively the f concentration is positively correlated with ph electrical conductivity and so4 2 in both areas the high f in groundwater resulted mainly from dissolution of biotite and fluorapatite in quartzofeldspathic gneiss the ionic dominance pattern in meq l is mostly in the order ca2 na mg2 k among cations and hco3 so4 2 f among anions in the karlakot groundwater preliminary adsorption experiments were conducted on natural haematite iron ore and synthetic magnetite to evaluate their potential for f removal from water effects of different parameters such as contact time ph adsorbent dose and initial f concentration on the adsorption capacity of these materials were investigated strong dependence of f removal on ph was observed for both the adsorbents with natural haematite iron ore the maximum f removal of 66 occurred at an initial ph of 3 2 for a solution with f concentration of 3 mg l adsorbent dose of 7 g l and overnight contact time the haematite iron ore was observed to increase the ph of the f solution adsorption equilibrium was not achieved with this adsorbent even after a contact time of 45 2 h in the case of synthetic magnetite 84 f removal was achieved after 2 min of contact time for a solution with f concentration of 6 mg l adsorbent dose of 10 g l and initial ph of 7 the results indicate high potential of both natural haematite iron ore and synthetic magnetite as adsorbents of f in water

stable isotope fractionation in live benthic foraminifera from the southern california borderland live specimens of benthic foraminifera have been analyzed from surface sediment samples collected from 108 to 1134 m depth in the southern california borderland the temperature and isotopic composition of the ambient water and dissolved inorganic carbon have also been measured to permit comparison of foraminiferal compositions to expected equilibrium values the species analyzed break down into four groups which reflect the influence of mineralogy aragonite vs calcite biological fractionation vital effect and microhabitat effects on isotopic composition the aragonitic hoeglundina elegans show an enrichment in 18o relative to equilibrium calcite of 0 41 0 in shallower water increasing to at least 1 06 0 in deeper water the 13c enrichment of h elegans relative to the dissolved inorganic carbon dic is also depth dependent increasing from 1 27 0 at 108 m to 2 13 0 at 940 m this depth dependence results from the change in composition of the dic the 13c composition of h elegans remains constant with depth for some unknown reason one possible explanation is that the change in composition of the dic is balanced by an increase in hoeglundina hco 3 fractionation with decreased temperature the 13c values of the cassidulina species are almost identical to those of the ambient dissolved inorganic carbon dic and reflect the decrease in the 13c of the dic with depth the 13c values of species not in 18o equilibrium vary independently of the changing composition of the dic there is a correlation between 13c and 18o among coeval species consistent with the model which explains vital effect as the result of incorporation of isotopically light metabolic co2 into the shell the magnitude of disequilibrium is relatively constant for 18o but not for 13c suggesting that in isotopic stratigraphy studies it may be difficult to calibrate the 13c of different species as has been done with 18o there appears to be a relationship between taxonomic group and vital effect the foraminifera in approximate 18o equilibrium with the water including species of cassidulina bolivina uvigerina and globobulimina are members of the family cassidulinidae or superfamily buliminacea those not in 18o equilibrium including species of pyrgo quinqueloculina triloculina and lenticulina belong to the families miliolidae and vaginulinidae no disequilibrium species have been found as yet in the low oxygen environments of the borderland this observation and published findings on the ultrastructure of benthic foraminifera suggest that isotopic behavior may be related to a foraminifer s ability to exchange gases rapidly with its ambient water

earthquake precursors in japan precursor time and detectability abstract earthquake precursor data amounting to 418 in number accumulated in japan are analyzed most data are obtained under the nation wide earthquake prediction programme the precursor time t versus main shock magnitude m relationship is different for different groups of precursors a linear relation such as log t a bm where a and b are constants seems to hold for precursor disciplines such as land deformation revealed by geodetic survey and tide gauge observation ground tilt observed by a water tube tiltmeter anomalous seismic activity and geomagnetic field change although a similar relationship seems to hold for the disciplines of earth currents radon concentration underground water etc the precursor time is substantially smaller for these disciplines than for the former disciplines the above characteristics of precursor time suggests that precursors closely connected to the dilatancy generation seem to be observed at an earlier stage of seismogenetic activity precursors probably associated with diffusion of underground water into the dilatant region seem to follow for a number of precursor disciplines such as foreshock ground tilt observed by a pendulum tiltmeter resistivity by a variometer and so on no dependence of t on m is found the relationship between m and the logarithmic epicentral distance d measured in kilometers is different from discipline to discipline relying on empirical and theoretical studies of coseismic strain step it turns out that precursors found by geodetic and geomagnetic observations seem to reflect a crastal strain of the order of 10 7 10 6 precursors obtained by a resistivity variometer seem to represent a strain of the order of 10 9 10 8 precursors of other disciplines seem to correspond to a strain of 10 8 10 7 it is clear that precursors can be detected further from the epicenter as the main shock magnitude becomes larger in some favourable cases a precursor can be observed even where the epicentral distance is several times larger than that of the epicentral area

dissolution of fluoride in groundwater a water rock interaction study fluoride rich groundwater is well known in granite aquifers in india and the world although its presence is necessary chances of health risk become high if the fluoride concentration is more than the permissible limit of 1 5 mg l world health organization who in drinking water fluoride mainly occurs in groundwater as a natural constituent results of a laboratory study on water rock interaction at normal temperature pressure and different chemical conditions indicate that the specific conductivity ph ca and hco3 are important chemical parameters for the dissolution of fluoride to groundwater from fluoride rich minerals e g fluorite experimental results indicate that an alkaline medium ph 7 6 to 8 6 high hco3 concentration ranging from 350 450 mg l and moderate specific conductivity ranging from 750 1 750 s cm are favourable for fluoride dissolution no significant correlation existed between fluoride and cahco3

hydrogeochemistry of roccamonfina volcano southern italy this is the first hydro geochemical investigation carried out on the roccamonfina volcanic complex groundwaters the chemistry of roccamonfina waters is defined by water rock and water rock gas interactions in fact interactions between rocks of the first eruptive high k formations and circulating groundwaters are recognized by high k concentrations on the other hand inverse concentration of calcium versus alkali metals is related to two different rock interactions occurring in different areas of the volcano a within the caldera where groundwaters flow within latite and pyroclastic formations releasing calcium and b similarly at the base of the volcano where groundwaters flowing from surrounding carbonates got strongly enriched in ca these geochemical processes are also associated with k se of caldera and mg ca in sites located at the ne base of the volcano decrease completely different dynamics occurs at riardo groundwaters se here waters are the result of a mix between the roccamonfina deep aquifer and the carbonate aquifer of the riardo plain rich co2 emissions make these waters strongly mineralized minor elements show a similar geochemical behavior of major ions and are crucial defining interactions processes the evolution of roccamonfina groundwaters is also evident along the simultaneous enrichment of ba sr and ca ba increase is the result of deep local carbonate alteration enhanced by co2 emissions and the lower sr ca ratio from 10 to 2 ppb ppm is also due to the same process in the light of our results the roccamonfina aquifer can be schematically divided into two main reservoirs a a superficial aquifer which basically follows the volcanic structure morphology and tectonics and b a deeper reservoir originating within the oldest roccamonfina volcano ultra potassic lavas and then flowing into the carbonate aquifers of the neighboring plain eventually the chemistry of the roccamonfina aquifer does not show any specific and visible pollution contrary to what happens in the volcano surrounding plains in fact only 14 of the samples we collected 206 show a no3 content 30 mg l these sites are all located at the base of the volcano near the plain

a candidate stratotype for the precambrian cambrian boundary fortune head burin peninsula southeastern newfoundland the burin peninsula exhibits an exceptionally thick and essentially continuous succession of marine strata through the precambrian cambrian transition fossils are abundant and include trace fossils small shelly fossils vendotaenid algae soft bodied megafossils and microfossils the burin peninsula is readily accessible and has long been considered a potential area for a precambrian cambrian boundary stratotype a continuous section through the upper part of member 1 and all of member 2 of the chapel island formation is exposed at fortune head and this section is herein proposed as a global stratotype for the precambrian cambrian boundary the boundary horizon is located 2 4 m above the base of member 2 of the chapel island formation this horizon marks the base of the basal cambrian phycodes pedum ichnofossil zone and immediately overlies the top of the late precambrian harlaniella podolica ichnofossil zone shelly fossils sabelliditids first appear a few metres below the proposed boundary sof

the spatial distribution and hydrogeological controls of fluoride in the confined and unconfined groundwater of tuoketuo county hohhot inner mongolia china insufficient or excessive intake of fluoride can create health problems for humans the objective of this study was to understand the occurrence of fluoride in groundwater as well as its spatiotemporal variation and sources in tuoketuo county hohhot inner mongolia china sixty seven water samples from 34 phreatic and 33 confined sources were collected from hand pumps dug wells and tube wells all samples were analyzed for ph electric conductivity ec total dissolved solids tds total hardness th as well as content of na k ca2 mg2 hco3 so4 2 cl and f the fluoride concentration in water samples varied from 0 40 to 7 20 2 33 1 79 and 0 06 to 12 70 1 65 2 38 mg l in phreatic and confined water respectively an analysis of the hydrogeochemical characteristic of samples indicated that the high fluoride content of groundwater was caused by the alkaline environment with high levels of hco3 na tds ec and with a ca2 deficiency the highest concentration of fluoride 5 mg l in phreatic water was located in the groundwater discharge area because this water was affected by the groundwater flow field in confined aquifers the concentration of fluoride was mainly controlled by lithology a high fluoride content 1 5 mg l was only observed in lacustrine platform zone in confined aquifers

neoproterozoic rocks of the newfoundland avalon zone abstract a ca 15 km thick succession of volcanic and sedimentary neoproterozoic rocks are exposed within the avalon terrane of newfoundland petrologic and geochemical study of volcanic suites and sedimentological analyses indicate that most deposition took place in ensialic rift basins and associated continental arc settings on the avalon peninsula over 7500 m of volcaniclastic strata include initial submarine fan and slope deposits which pass upward into a prograded wedge of deltaic and fluvial deposits this flysch to molasse transition and associated folding and volcanism mark the neoproterozoic avalonian orogeny post orogenic erosion was followed by deposition of extensive cambrian siliciclastic deposits recent u pb zircon dating of many of the neoproterozoic volcanic units provides some constraints on both intra avalon and global correlations more precise dates are needed to improve correlation and better constrain the geologic history of this region glaciogenic diamictites of the gaskiers formation exposed on the avalon peninsula may eventually also prove useful for global correlation biostratigraphic study of the latest neoproterozoic lower cambrian deposits has resulted in ratification of the precambrian cambrian boundary stratotype in an exposure on the burin peninsula older neoproterozoic rocks contain well preserved ediacara type fossils and a low diversity suite of microfossils including acritarchs and carbonaceous filaments the latter of which have little biostratigraphic utility aside from work on the precambrian cambrian boundary section little or no chemostratigraphic magnetostratigraphic or sequence stratigraphic work has been completed on the neoproterozoic of the newfoundland avalon terrane

about the potential of wells to reflect stress variations within inhomogeneous crust abstract kumpel h j 1992 about the potential of wells to reflect stress variations within inhomogeneous crust in t mikumo k aki m ohnaka l j ruff and p k p spudich editors earthquake source physics and earthquake precursors tectonophysics 211 317 336 numerous pre co and post seismic well level changes that are believed to reflect stress variations in the crust have been observed in various parts of the world so far analysis of these data has not favoured a distinct model of the processes that could be involved the benefit from the signals is in fact limited because understanding of the underlying physical mechanisms is poor the paper discusses the impact that inhomogeneities in the brittle crust can have on the observations in particular the following problems are considered 1 could the well level signals be induced by the invasion of pressurized pore fluid at some place 2 could the hydrological conditions close to the observation well modulate any remote pore pressure variation 3 which features of the crust are most likely to dominate the process of stress transfer in the crust 4 how should a stress sensitive well be designed the results can be summarized as follows 1 stress diffusion due to the invasion of pressurized pore fluid can lead to significant well level changes only when the source region is at closer distance than a few kilometres probably less than a few hundred metres from the well 2 local inhomogeneities in the vicinity of the observation well may strongly influence the well s response to remote pressure changes even sign reversal of the anomaly may be encountered 3 there is increasing evidence that the wide range of stiffness values of natural rocks from 100 mpa or less till 100 gpa manifested in a fractal distribution of fault like weak zones within relatively stiff formations dominates stress transfer in the brittle crust uncertainty about the effective rheology for time scales from 10 4 to 103 years limits the inversion of many geophysical observations at present 4 of various configurations a well tapping an extensive hydraulic fracture could act best as a sensitive stress sensor provided that the fracture volume is isolated from the pore space of the host rock however experimental evidence of the practicability of such configuration is still due the weakness of conventional wells as stress sensors results from the fact that the process of fluid flow often lacks a sufficient control on attenuation mechanisms for low frequency well level variations regardless of whether the wells end in stiff or weak formations to a large extent the presented findings are compiled from publications of investigators working in various fields

geochemical appraisal of fluoride contamination of groundwater in the nayagarh district of orissa india the occurrence of high concentrations of fluoride in groundwater 1 5 mg l in the villages of singhpur and sagaragan in the nayagarh district of orissa and its relation with the fluoride rich hot spring water 10 mg l located nearby have been studied the composition of the hot spring water is very comparable to the other thermal waters of the world thermodynamic considerations show that more than 65 of the groundwater and hot spring water samples are oversaturated with calcite and only four samples are oversaturated with fluorite fluoride concentration shows a positive relation to sodium bicarbonate and ph and a negative relation to calcium and magnesium in fluoride rich groundwater and hot spring water principal component analysis shows that the fluoride rich groundwater was produced due to a mixing of hot spring water with the surrounding groundwater studies of the saturation index of fluorite with log electrical conductivity also indicate mixing of hot spring water with the surrounding groundwater the spatial distribution of fluoride in groundwater follows the topography of the area

two decades of research on the proterozoic phanerozoic transition 1972 1991 the most radical global change involving the biology chemistry and physics of life occurred near and at the stratigraphical level of the boundary between the neoproterozoic system precambrian and the cambrian system this stratigraphical level is held by consensus to be the proterozoic eonothem phanerozoic eonothem boundary and is regarded as being of fundamental importance research has involved not only archaeocyathans shelly small problematica earliest trilobites stromatolites and algae trace fossils soft bodied metazoans microphytolites and acritarchs but also physical and chemical aspects radio isotope dating carbon strontium and oxygen isotope stratigraphy polar wandering relating to palaeogeography and magnetostratigraphy a selected bibliography 1985 1990 is appended to enable further reading of the extensive research contributions

late neoproterozoic to early palaeozoic palaeogeography of avalonia some palaeomagnetic constraints from nuneaton central england palaeomagnetic studies have been carried out on neoproterozoic cambrian and ordovician rocks in the nuneaton inlier england 52 5 n 1 5 w three magnetic components were recognized which provide a consistent structural and magnetic history of the inlier neoproterozoic volcaniclastic and intrusive rocks acquired a characteristic remanent magnetization chrm dated at 603 ma late ordovician rocks are represented by lamprophyre and diorite intrusions and their chrms were probably imprinted during their emplacement at about 442 ma the lower cambrian sedimentary sequence of the hartshill sandstone formation which unconformably overlies the neoproterozoic rocks and hosts the ordovician intrusions does not preserve a primary magnetization but shows the imprints of the late ordovician 442 ma remagnetization as well as a probable end carboniferous remagnetization palaeolatitudes calculated for the late neoproterozoic rocks and ordovician intrusions are in good agreement with other palaeolatitudes calculated for avalonia during those times both the late neoproterozoic and late ordovician rocks additionally show chrms with declination anomalies indicating a large tectonic rotation of the nuneaton area possibly during one of the caledonian phases of deformation affecting southern britain

high resolution environmental reconstruction in sw peloponnese greece covering the last c 6000 years evidence from agios floros fen messenian plain a paleolimnological record from the central messenian plain southwestern peloponnese southern greece indicates rapid changes in the water level and chemistry of a transient lake on the flanks of the taygetos mountains during the last c 6000 years the analyses are based on diatoms as well as carbon and nitrogen isotopes from bulk sediments in a 7 5 m long sediment core retrieved from the drained fen of agios floros at the northern banks of the ancient river pamisos the sequence consists of fen peat in the uppermost section underlain by lacustrine sediments which are punctuated by two layers of clay with diatomaceous silt bands high accumulation rate is recorded in the oldest part of the section up to 23 mm yr particularly during two decadal long periods centered at c 5700 and c 5300 cal bp the diatom record reveals pronounced peaks in the planktonic taxon cyclotella distinguenda which correspond to the laminated sequences reflecting the rapid development of a deep lake with an open water

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

a systematic compilation of earthquake precursors article a survey of published scientific literature was undertaken to identify and catalog observed earthquake pre cursors the earthquake precursors selected for analysis included electric and magnetic fields gas emissions groundwater level changes temperature changes surface deformations and seismicity for each of these precursors the published scientific literature was searched to document the statistics of each reported earth quake precursor spatial extent time duration amplitude signal noise ratio to analyze dependence of the observable for each precursor on earthquake magnitude and to explore proposed physical models to explain eachearthquakeprecursor somegeneralcharacteristics wereobservedfortheseprecursoryphenomena first the largest amplitude precursory anomalies tend to occur before the largest magnitude earthquakes also the number of precursory anomalies tends to increase the closer in time to the occurrence of the earthquake finally theprecursoryanomaliestendtooccurclosetotheeventualepicenterof theearthquake ingeneral the physical models indicate that all of the precursory phenomena are related to deformation that occurs near the fault prior to the main earthquake while the models provide plausible physical explanations for the pre cursors there are many free parameters in the models that are poorly resolved

the proterozoic cambrian transition within the charnian supergroup of central england and the antiquity of the ediacara fauna a revised interpretation for the charnian supergroup is suggested from ichnological and lithological comparisons with the cambrian of nuneaton and other parts of the avalonian superterrane late neoproterozoic volcaniclastic sediments contain an ediacara fauna in the maplewell group these are succeeded by one or more inferred erosional breaks and overlain by passive margin sediments quartzarenites glauconitic greywackes pelites of the brand group which yield cambrian trace fossils including abundant large teichichnus this transformation is compared with that between the neoproterozoic caldecote volcanic formation and the cambrian hartshill formation at nuneaton the hanging rocks formation of the brand group lies above a major erosional break but shares a volcanogenic island arc petrology with the underlying maplewell group conglomeratic sandstones at the base of the brand hills formation contain purple pelite clasts comparable with underlying lithologies plus clasts of weathered diorite showing granophyric textures identical to those seen in the enigmatic south charnwood diorites nd sm isotope studies confirm the geochemical similarity between these diorites and those that intruded the caldecote volcanics at nuneaton previously u pb zircon dated at 603 2 ma these strong similarities with the nuneaton succession suggest that deposition of the brand hills formation in the cambrian was preceded by the local unroofing of diorite and erosion of underlying mudrocks much as seen in other parts of avalonia a date of 603 2 ma for the south charnwood diorites provides a minimum age for the local ediacara fauna but this is in need of substantiation

factors constraining the geographic distribution of earthquake geochemical and fluid related precursors abstract earthquake precursors are elusive and this elusiveness has hampered earthquake prediction in this paper the available catalogues of historical and contemporary geochemical and fluid related precursors of earthquakes are considered the locations of recording sites are mapped and compared with data concerning volcanic locations heat flows crustal velocities and the depth of seismic events possible relations among the considered geophysical parameters and the occurrence of fluid related earthquake precursors are discussed only some geological and geophysical conditions may allow for the occurrence of fluid related earthquake precursory phenomena as a consequence the geophysical models utilized to explain the occurrence of earthquake precursors should be updated furthermore only some areas of the world are deemed suitable for earthquake fluid related precursor monitoring

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

major ion signatures for identification of geochemical reactions responsible for release of fluoride from geogenic sources to groundwater and associated risk in vaniyar river basin dharmapuri district tamil nadu india fluoride is a common constituent in most of the rocks and the release of fluoride into groundwater is the major problem in several parts of the world the present study was carried out with the objective of identifying sources and mechanism of release of fluoride from the rocks and its impact on human health in vaniyar river basin dharmapuri district tamil nadu groundwater samples were collected from 44 wells once in 2 months from june 2011 to august 2014 and analyzed for major cations and anions using an ion chromatograph the possible reasons for the increased concentration of fluoride in groundwater of the area were investigated by taking into account of the agricultural practises and the major rock types in the area the observed order of the dominance of cations in groundwater in the study area is na ca2 mg2 k and that of anions is cl hco3 so42 co3 f the fluoride concentration in groundwater of this region ranges from 0 15 to 6 14 mg l out of 569 samples analysed fluoride concentration exceeded the maximum permissible limit of the drinking water standards of bis 1 5 mg l in 396 samples many people living in this area are suffering from dental and skeletal fluorosis due to prolonged use of fluoride rich groundwater for drinking concentration of fluoride in groundwater is relatively low in wells located in charnockite region whereas the concentration of fluoride in groundwater is high in the deep wells in regions comprising of epidote hornblende biotite gneiss the major source of fluoride in groundwater in the area is due to leaching of fluoride bearing minerals fluoride ions from biotite and hornblende minerals leach into the groundwater and contribute high fluoride concentration in this region the concentration of fluoride in groundwater increases when the water level is deep indicating higher release of fluoride from greater depth the geochemical reactions that control the release of fluoride from fluoride bearing minerals such as biotite and hornblende into groundwater were identified removal of high concentration of fluoride from drinking water is necessary in this region and measures should be taken to supply water after removal of fluoride for the betterment of the livelihood in the area

carbon isotope geochemistry and palaeontology of neoproterozoic to early cambrian siliciclastic successions in the east european platform poland a well preserved stratigraphic record of the organic carbon isotopic composition across the precambrian cambrian transition has been obtained from a sequence of entirely detrital rocks underlying the lublin slope east european platform poland the observed 13 c pattern for organic carbon is comparable to isotope data determined for coeval carbonate platform sequences elsewhere these results underline the truly global nature of these secular variations within the carbon cycle during the terminal proterozoic and early cambrian largely independent of host lithology and facies the direct combination of micropalaeontological and geochemical results from sedimentary organic matter allows a detailed interpretation of the isotope record as probably caused by secular changes in the net balance of burial and erosion rates of repositories of organic carbon furthermore these variations appear to be directly correlatable with changes in the diversity and abundance of the biota and radiation extinction events

trace elements and sr and c isotopic signatures in late neoproterozoic and earliest cambrian sedimentary organic matter from siliciclastic successions in the east european platform sedimentary organic matter deriving from tubes of sabelliditids vendotaenids sapropelic films and kerogens was extracted by acid processing from upper vendian siliciclastic successions in the east european platform elemental composition obtained by ins

temporal and spatial correlations between soil co2 flux and crustal stress in seismically active areas tectonic stress deforms and breaks the rocks of the crust ongoing deformation produces detectable modifications in the shallower portions of the crust resulting in a wide variety of changes in several parameters in this paper we report the results of a large scale spatial across an area of 15 000 km2 and temporal up to 3 years investigation of the relationship between active crustal stress and soil co2 flux we deployed a network of 10 automatic stations in most of the seismically active districts of southern italy to monitor the soil co2 fluxes and we used seismicity data to track crustal stress the results of the investigation show that the co2 flux signals varied independently in the districts with low and sporadic seismicity conversely in the only district with nearly continuous seismic activity almost all of the co2 flux signals were well correlated with each other and we recorded a clear synchronous sharp increase of the seismicity and signals recorded by several stations the high spatial and temporal correlation between seismicity and gas discharge evidenced in this study prove that the crustal stress associated with the seismogenic process is able to effectively modulate the gas release in a seismically active area

genesis of high f groundwaters southern india abstract high f groundwaters are common in the dry parts of the indian peninsula constituting a serious health problem the f originates mainly from hydroxypositions in biotite and hornblende and is concentrated through evapotranspiration in soil and groundwater exhibiting residual alkalinity such waters are common in areas with generally alkaline soils along the flow paths of the water from hilltops to valley bottoms calcite dolomite and fluorite seem to precipitate in that order a practical solution to the health problem may be to locate drinking water wells in upslope positions

dating the cambrian purley shale formation midland microcraton england zircons from a bentonite near the base of the purley shale formation in the nuneaton area warwickshire yield a 206pb 238u age of 517 22 0 31 ma based on the fauna of small shelly fossils and the brachiopod micromitra phillipsii in the underlying home farm member of the hartshill sandstone formation trilobite fragments that are questionably referred to callavia from the basal purley shale formation and the presence of trilobites diagnostic of the sabulosa biozone 66 m above the base of the purley shale formation the bentonite likely dates an horizon within cambrian stage 3 at about the level of the fallotaspis or basal callavia biozone this is consistent with bentonite ages from other localities in southern britain which constrain the age of the lower and uppermost parts of cambrian stage 3 the new date provides additional chronological control on the earliest occurrence of trilobites in the midland microcraton a date for the marine transgression at the base of the purley shale formation and is the first radiometric age from the cambrian succession of warwickshire

cambrian and ordovician stratigraphy related to structure and seismic profiles in the western part of the english midlands in england the cambrian successions include relatively continuous dominantly argillaceous sequences nuneaton area 900 m thick and arenaceous successions punctuated by hiatuses malvern shropshire the tremadoc lower ordovician succeeds paraconformably it is widespread dominantly argillaceous and locally very thick 2000 m deposition of the lower tremadoc is thought to have been rapid uplift of regional extent occurred in early ordovician post tremadoc times and inversion of the basins such as the tremadoc worcester graben occurred during the variscan orogeny the disposition of the cambrian tremadoc beneath the upper llandovery unconformity is thought to reflect the arrangement of basins and highs at that time evidence from seismic profiles indicates deposition in half grabens in the welsh borderland evidence from outcrops and boreholes suggests that the st david s series middle cambrian is locally thickened against syn depositional faults the thinning and local absence of the st david s series across such faults is attributed to the influence of tilt block highs rifting and tilting allowed thick tremadoc to accumulate e g in a precursor worcester graben but evidence for the direction of thickening is masked by lack of seismic markers and by the effect of pre landovery erosion

carbon isotopes and precambrian cambrian boundary geology south australia ocean basin formation seawater chemistry and organic evolution a carbon isotope stratigraphy from the lowest cambrian strata in the adelaide fold belt of south australia is interpreted in terms of the geological context of the sequence major transgression developing circulation patterns and upwelling resulting from an adjacent opening ocean and biomass increases stemming from the cambrian radiation event there is also evidence from the textures of ooids and cements in late precambrian cambrian strata for subtle variations in seawater chemistry across the boundary and these may well have been instrumental in the development of calcareous skeletons in the early metazoans

isotopic evidence for the early meteoric diagenesis of the reef facies permian reef complex of west texas and new mexico abstract multiple isotopic analyses of former aragonitic marine cements from a single sample of permian reef complex reef facies define a linear covariant trend with a positive slope each individual analysis represents a different mixture of two isotopically distinct phases which are too finely intergrown for separate analysis in order to assess the systematic variation of the isotopic composition of these calcite phases over a paleobathymetric range samples were collected from four sites a through d along a single upper capitan paleoslope reflecting the transition from reef massive through reef foreslope facies on a plot of 13c versus 18o the convergence f four marine cement trends from these four sites indicates that the isotopically enriched phase is invariant whereas the depleted phase a luminescent calcite intergrowth along original marine cement intercrystalline boundaries varies systematically with position on the paleoslope the emplacement of the calcite intergrowth in the marine cements is intimately related to the earliest episodes of equant calcite spar precipitation at the shallowest paleodepths sites a through c the compositions of the first generation of calcite spar spar i clusters around a mean 18o of 8 2 and is progressively less depleted in 13c from site a to site c as this variation is also present in the marine cement trends it is concluded that both the intergrowth and spar i represent successive episodes of calcite precipitation during a single diagenetic event at the deepest paleodepth site d sp r i is absent and the calcite intergrowth is interpreted to have the same composition as the second generation of spar spar ii 12 3 18o and 0 0 13c which can be found throughout the reef facies on the basis of its relatively constant oxygen composition the systematic enrichment of its carbon composition with increasing paleo depth and its absence from the deepest site on the paleoslope we conclude that the spar i diagenetic event represents the establishment of a meteoric phreatic system in the reef facies characterized by well defined downdip gradients in rock water interaction furthermore isotopic evidence of fresh water alteration of allochthonous massive facies reef debris deposited in foreslope strata near site d and below the limit of the spar i diagenetic event suggests that this meteoric system was active contemporaneously with the growth of the reef complex interpretation of the spar ii diagenetic event is less clear cut the associated diagenetic fluid probably did not have marine or hypersaline oxygen signatures as this would require the persistence of aragonite mineralogies to temperatures over 70 c and burial depths of at least i kin spar il was probably precipitated from meteoric water with a 18o similar to that of the spar i meteoric water at temperatures between 30 65 c unlike the spar i diagenetic event the spar ii event shows no association with depositional systematics hence we tentatively suggest that spar ii may have been related to a presumed ochoan or younger regional meteoric or shallow burial phreatic system

cambrian evolutionary radiation context correlation and chronostratigraphy overcoming deficiencies of the first appearance datum fad concept abstract use of the first appearance datum fad of a fossil to define a global chronostratigraphic unit s base can lead to intractable correlation and stability problems fads are diachronous they reflect species evolutionary history dispersal biofacies preservation collection and taxonomy the cambrian evolutionary radiation is characterised by diachronous fads biofacies controls and provincialism of taxa and ecological communities that confound a stable lower cambrian chronostratigraphy cambrian series and stage definitions require greater attention to assemblage zone successions and non biostratigraphic particularly carbon isotope correlation techniques such as those that define the ediacaran system base a redefined basal cambrian trichophycus pedum assemblage zone lies above the highest ediacaran type biotas vendobionts putative metazoans and calcareous problematica such as cloudina and the basal asteridium tornatum comasphaeridium velvetum zone acritarchs this definition and the likely close correspondence of evolutionary origin and local fad of t pedum preserves the fortune head newfoundland gssp of the cambrian base and allows the presence of sub cambrian branched ichnofossils the sub tommotian equivalent base of stage 2 a suggested laolinian stage should be defined by the i l4 zhuce 13 c positive peak bracketed by the lower ranges of watsonella crosbyi and aldanella attleborensis molluscs and the skiagia ornata fimbrioglomerella membranacea zone acritarchs the w crosbyi and a attleborensis fads cannot define a stage 2 base as they are diachronous even in the newfoundland type w crosbyi zone the series 2 base cannot be based on a species fad owing to the provincialism of skeletalised metazoans in the terreneuvian series 2 boundary interval and global heterochrony of the oldest trilobites a series 2 and stage 3 a suggested lenaldanian series and zhurinskyan stage new gssp base is proposed at the siberian lower atdabanian 13 c iv peak which correlates into south china avalonia and morocco and assigns the oldest trilobites to the terminal terreneuvian series

controls on the genesis of some high fluoride groundwaters in india india has an increasing incidence of fluorosis dental and skeletal with some 62 million people at risk high fluoride groundwaters are present especially in the hard rock areas south of the ganges valley and in the arid north western part of the country the phenomenon is related to groundwater with residual alkalinity ca2 hco3 fluoride concentrations are governed by adsorption equilibria and by fluorite solubility evapotranspiration leads to a precipitation of calcite a lowering of ca activity and increase in na ca ratios and this allows an increase in f levels in southern india mg seems to be controlled by dolomite while sepiolite and palygorskite are mg sinks in rajasthan but may then release f under alkaline conditions the latter two minerals are probably also important sources and sinks for f in the hydroxy positions the increase in the extent of sodic soils as a result of irrigation is a contributing factor to the increasing incidence of fluorosis remedial measures including addition of gypsum and rainwater harvesting are needed even in areas where the sodicity does not cause structural problems in the soil

genesis and geochemistry of high fluoride bearing groundwater from a semi arid terrain of nw india occurrence of fluoride in natural water resources and the associated health hazards have been reported from many parts of india during the last decade with the objective of organizing a systematic scientific programme to understand the geochemical behaviour of fluoride in natural water resources in relation to the local hydrogeological climatic conditions and agricultural use a typical semi arid terrain in the northwestern part of india was chosen for detailed study the present work is an attempt to study the fluoride contamination in groundwater in parts of jaipur district rajasthan state and to assess the origin and genesis of fluoride in groundwater the area falling under the semi arid tract of central rajasthan is geologically occupied by alluvial formations and precambrian rocks gneisses and schists where groundwater occurs under unconfined to semi confined conditions a total of 66 groundwater samples was collected during the pre monsoon period and analysed which gave a concentration of fluoride in water in the range of 0 35 to 9 3 mg l with 62 of the samples in excess of permissible limit of 1 5 mg l as compared to alluvial formations fluoride enrichment in groundwater is higher in hard rock areas the samples collected from the granite gneissic terrain show higher values when compared to those in the schist the groundwater of the shallow aquifers soil clay complex weathered zone has a higher concentration of fluoride than the deep fractured hard rock aquifer does the possible sources of fluoride are chemical weathering and leaching of fluorine bearing minerals present in hard rocks and alluvial formations under the alkaline environment in arid to semi arid conditions high ph as well as alkalinity and low levels of ca mg and total hardness suggest favourable chemical conditions for the fluoride dissolution process a higher rate of evapotranspiration intensive and long term irrigation and heavy use of fertilizers are the supplementary factors that further increase the fluoride content in the groundwater a groundwater management programme is suggested

short term groundwater level variations in a seismic region as an indicator of the geodynamic regime abstract an analysis of short term up to 5 days variations in the groundwater level has been made for a group of wells in turkmenistan where observations in search of earthquake precursors have been carried out for many years a great number of groundwater level variations which reflect active geodynamic processes were found in wells located in the main kopetdag fault zone these variations are a response to relatively rapid movements in the fault zone a number of specific features of the recent crustal movements were determined from the character of the groundwater level variations these features are the preferential coincidence of the directions of rapid and slow movements variation in the deformation rates in different portions of the fault and a change in the movement rate with time about 56 of the short term groundwater level variations proceded or accompanied earthquakes the rest of the variations were a response to aseismic movements the characteristics of the precursory variations imply that before the earthquake in the fracture zone substantial short term deformations occur at a rate 1 4 orders larger than the estimated values of deformations the dependence of the amplitudes of short term groundwater level variations and earth tide level fluctuations on the position of observation wells with respect to the fault has been elucidated these amplitudes and the number of recorded variations are larger near the fault indicating intensified deformations and enhanced strain sensitivity of the well reservoir system in the vicinity of major tectonic disturbances the investigations conducted point to the high information content of special hydrogeological observations for monitoring recent geodynamic activity

oxygen and carbon isotope stratigraphy of early cambrian carbonates in southeastern newfoundland and england carbonate rocks have been sampled through predominantly siliciclastic sediments above the precambrian cambrian global stratotype level in southeastern newfoundland to assess their potential for oxygen and carbon isotope stratigraphy comparable successions were sampled at nuneaton and comley in england greatly depleted 18 o signals are attributed to widespread thermal alteration during deep burial and granitic intrusion including within the stratotype region carbon isotope ratios appear to have been less affected and these are described from nine sections a provisional composite 13 c curve is based on non ferroan pink nodular and bedded micrites several 13 c excursions occur in the fossiliferous bonavista group and allow the position of the tommotian atdabanian boundary to be identified chemostratigraphic correlation of the new precambrian cambrian boundary stratotype may however prove difficult because of the lack of suitable well preserved carbonates the search must begin for a comparable reference section allowing global correlation of the boundary level using chemostratigraphy as well as biostratigraphy

anomalous water level changes and possible relation with earthquakes since late 1976 abandoned water wells have been monitored along the san andreas and san jacinto faults to detect water level changes which may be premonitory to earthquakes an m5 5 earthquake occurred 25 february 1980 within the san jacinto fault zone near anza the water level in a continuously recorded well in borrego valley 35 km from the epicenter rose 0 5 m and returned to its prior level during a four hour period beginning 88 hours before the earthquake the water level in this well had been remarkably steady compared to other wells being monitored another well in borrego valley showed a much smaller rise and fall in water level at the same time because these changes are unique for the long term records of these wells they may represent precursors to the earthquake several wells along the palmdale valyermo segment of the san andreas fault showed possibly anomalous long term water level changes which are not clearly related to rainfall between early 1979 and early 1980 water levels in six wells were 6 to 4 5 m higher and levels in two wells were about 3 m lower than would have been predicted based on the previous records the water level increases could have been the result of delayed response to seasonal rainfall following a long drought however it is interesting that the possibly anomalous water level changes first occurred at the same time as the reported changes in strain pattern from compression to expansion along the san andreas fault in the same area

stable isotope geochemistry of the lower cambrian sekwi formation northwest territories canada implications for ocean chemistry and secular curve generation abstract three curves delineating 13 c variations across the early cambrian sekwi formation carbonate ramp mackenzie mountains northwest territories canada are incorporated into a biostratigraphic and sequence stratigraphic framework that provides a higher resolution temporal and spatial framework for the sekwi formation the three 13 c curves were correlated across a range of depositional environments from tidal flat to deep subtidal on the sekwi carbonate ramp eight 13 c cycles in the curves a h were correlated across the basin complimenting the sequence stratigraphic framework the most complete 13 c curve from the sekwi formation correlates well with a composite early cambrian 13 c curve from the siberian platform however the differing magnitude and absolute timing of some of the correlative isotopic excursions records the influence of regional tectonism sea level changes and diagenesis on the sekwi ramp additionally the sekwi formation 13 c curve has more high frequency variations than the siberian curve due in part to the higher sample density used to construct the sekwi curve the early middle cambrian boundary was not sampled in this study but a large negative isotopic excursion in the very latest early cambrian coincides with a regional drowning that may be correlative throughout western laurentia but recognizing this event globally is problematic

assessment of processes controlling the regional distribution of fluoride and arsenic in groundwater of the pampeano aquifer in the del azul creek basin argentina abstract groundwater in the upper 50 m of the pampeano aquifer in the del azul creek basin argentina has f and as contents above the who safe drinking levels this basin is situated to the se of the chaco pampean plain in buenos aires province the pampeano aquifer is a major water source for all uses the aim of the study is to assess the primary processes controlling the regional distribution of f and as in the most exploited part of the aquifer the study involved sampling for chemical and isotopic analyses interpretation of data with different methods diagrams bivariate analyses mineral saturation states principal component analysis and deduction of leading processes information about aquifer mineralogy and hydrogeochemical processes involved in f and as solubilization in the aquifer has been taken from previous works of the same and other authors groundwater salinity increases to the ne in the direction of the regional groundwater flow chemical types evolve from ca mg hco 3 in the upper part of the basin to na hco 3 in the middle part and to na clso 4 and na cl in the lower part the regional distribution of f is controlled by hydrogeochemical processes the distribution of as is controlled by two types of processes dominating in different areas hydrogeochemical controls prevail in the low to moderately mineralized groundwater of the middle and lower parts of the basin hydrogeological controls lead to the ne of the lower basin and beyond it in the last zone there are abundant lagoons and seasonal flooding is frequent making evapoconcentration an important process for groundwater mineralization the main hydrogeochemical processes involved in both f and as distribution are cation exchange with na release and ca uptake carbonate dissolution and ph increase arsenic release induced by redox processes may play to the ne but its results would be masked by the effect of evaporation

degassing of halogens from basaltic volcanism insights from volcanic gas observations abstract the currently available data set of s cl f abundances in volcanic gas plumes and high temperature fumarolic gas samples from basaltic volcanism is reviewed here in the attempt to derive constraints on the modes of halogen degassing from mafic silicate melts apart from large volcano to volcano variations reflecting remarkable differences in volatile abundances in the source magmas each of the explored volcanoes displays large changes of so2 hcl and so2 hf ratios with the style of volcanic activity with hcl hf staying fairly constant halogen abundances are low and so2 hcl and so2 hf are high when fresh volatile rich magmas sustain degassing as during explosive eruptions at the onset of eruptive cycles or shortly before paroxysmal events low so2 hcl and so2 hf ratios are instead characteristic of late stages of volcanic degassing typically being observed in the concluding stages of basaltic eruptions or during periods of reduced magma supply at persistently degassing volcanoes these observations are taken as evidence of halogens being less keen to enter the gas phase relative to s during degassing of basaltic magmas and quantitatively interpreted in light of a rayleigh type open system degassing model the model though simple quantitatively reproduces the range of volcanic gas compositions observed at basaltic volcanoes worldwide and allows prediction of vapour melt partitioning contrasts of factors 9 and 36 for the volatile couples s cl and s f respectively these predictions require validation from appropriately designed experiments of halogen partitioning between magmatic vapours and silicate melts over a range of p t x conditions

pore pressure variation as a precursory phenomenon the need for and a list of supplementary data abstract pore pressure variations are believed to play a dominant role in the earthquake cycle well level fluctuations that reflect possible pore pressure anomalies prior to earthquakes have been reported by many authors the evaluation of the reliability of hydrologie precursors and appropriate fault models is however difficult because the background information provided with the published data is generally sparse following the idea of roeloffs 1988 an extended list of recommendations for improved documentation of hydrologic precursors is presented the list includes basic information on the construction of the well the well s hydrologic environment the pore fluid fluctuations of the well level and other signals and earthquake related information

correlation of the cambrian evolutionary radiation geochronology evolutionary stasis of earliest cambrian terreneuvian small shelly fossil ssf taxa and chronostratigraphic significance early faunas with watsonella crosbyi with or without aldanella spp have been equated with the siberian tommotian stage uppermost terreneuvian and used to define a proposed cambrian stage 2 base much earlier terreneuvian occurrences are now shown by recovery of these micromolluscs below the i carbon excursion in the siberian nemakit daldynian stage and comparable 13 c excursions in the middle meishucunian china and middle chapel island formation avalonia this 13 c excursion a reliable stage 2 marker lies in a c 10 ma interval in the cambrian radiation in which long ranged small shelly fossil taxa provide limited biostratigraphic resolution

stable isotope composition of benthic foraminifera from the equatorial pacific when ranked according to deviation from isotopic equilibrium deep sea benthic foraminifera exhibit no correlation between the rankings for oxygen and for carbon both rank sequences are stable from east to west in the equatorial pacific fertility independent and from glacial to post glacial time independent records for the past 15 000 yr suggest marked changes in deep sea circulation during this time interval