dolomites and dolomites in mesozoic platform carbonates of the southern apennines geometric distribution petrography and geochemistry abstract a multidisciplinary study of the dolomitized bodies present among the late triassic to late cretaceous carbonate deposits of the monti lattari belt southern apennines of italy compares the different dolomitization styles present within this succession of these mesozoic platform carbonates and furnishes an overview of their formative genetic models the revealing traces of the diverse modes of diagenesis in this region include both surface and subsurface mechanisms utilizing a geometric reconstruction of the dolomitized bodies an integrated facies and petrographic analysis of the components and a geochemical characterization of the sediments including detailed mineralogy and associated stable isotope values the data presented demonstrate that some intervals are characterized by surface related dolomitization processes middle late triassic and cretaceous while others latest triassic to lower middle jurassic and are mainly dominated by later large scale subsurface dolomitization processes all of the middle late triassic norian successions are pervasively dolomitized exhibit fabric preserving textures and have a distinctly heavy stable isotope signature their origin has been related to diagenesis due to particular climatic and palaeoceanographic conditions leading to the formation of extended blankets of shallow warm saline seawater this setting was terminated by climatic and palaeoceanographic changes during the latest triassic which dramatically reduced the significance of surface related dolomitization on a regional scale the overlying latest triassic rhaetian outcrops consist of a widespread coarse fabric destructive massive dolomite with a lighter isotopic signature these dolomites seem genetically related to the ones of the lower middle jurassic which share the same geometrical petrographic and geochemical characteristics caused by large scale fluid circulation this diagenetic pattern apparently started in the early jurassic during burial driven by thermal convection due to the different temperatures between the oceanic waters and the warmer carbonate platform the middle upper jurassic units feature local episodes of early dolomitization that partially replaced the muddy carbonate facies due to tidal pumping and reflux mechanisms dolomitization is not a pervasive feature during this phase of deposition in the cretaceous portion of the succession dolomites have a totally different and distinct character and are generally related to bedding and show variability in textures and mg ca ratios local association with evaporites geometry of dolomitized bodies and stable isotope geochemistry suggest processes comprising evaporative pumping and reflux all related to the surface environment this evidence points to a renewal of a climatic context more favorable for early dolomitization thus this study permits recognition of the presence of three quite different dolomitization styles within the carbonate platform succession of the southern apennines fold thrust belt one ascribed to the norian one to the rhaetian lower jurassic and one to the cretaceous

microbe mineral interactions early carbonate precipitation in a hypersaline lake eleuthera island bahamas microbialites benthic microbial carbonate deposits were discovered in a hypersaline alkaline lake on eleuthera island bahamas from the edge towards the centre of the lake four main zones of precipitation could be distinguished 1 millimetre sized clumps of mg calcite on a thin microbial mat 2 thicker and continuous carbonate crusts with columnar morphologies 3 isolated patches of carbonate crust separated by a dark non calcified gelatinous mat and 4 a dark microbial mat without precipitation in thin section the precipitate displayed a micropeloidal structure characterized by micritic micropeloids strong autofluorescence surrounded by microspar and spar cement no fluorescence observations using scanning electron microscopy sem equipped with a cryotransfer system indicate that micrite nucleation is initiated within a polymer biofilm that embeds microbial communities these extracellular polymeric substances eps are progressively replaced with high mg calcite discontinuous eps calcification generates a micropeloidal structure of the micrite possibly resulting from the presence of clusters of coccoid or remnants of filamentous bacteria at high magnification the microstructure of the initial precipitate consists of 200 500 nm spheres no precipitation is observed in or on the sheaths of cyanobacteria and only a negligible amount of precipitation is directly associated with the well organized and active filamentous cyanobacteria in deeper layers of the mat indicating that carbonate precipitation is not associated with co2 uptake during photosynthesis instead the precipitation occurs at the uppermost layer of the mat which is composed of eps empty filamentous bacteria and coccoids gloeocapsa spp two dimensional mapping of sulphate reduction shows high activity in close association with the carbonate precipitate at the top of the microbial mat in combination these findings suggest that net precipitation of calcium carbonate results from a temporal and spatial decoupling of the various microbial metabolic processes responsible for caco3 precipitation and dissolution theoretically partial degradation of eps by aerobic heterotrophs or uv fuels sulphate reducing activity which increases alkalinity in microdomains inducing caco3 precipitation this degradation could also be responsible for eps decarboxylation which eliminates ca 2 binding capacity of the eps and releases ca 2 ions that were originally bound by carboxyl groups at the end of these processes the eps biofilm is calcified and exhibits a micritic micropeloidal structure the eps free precipitate subsequently serves as a substrate for physico chemical precipitation of spar cement from the alkaline water of the lake the micropeloidal structure has an intimate mixture of

hydrogeochemical processes in the groundwater environment of heihe river basin northwest china the heihe river basin is a typical arid inland river basin for examining stress on groundwater resources in northwest china the basin is composed of large volumes of unconsolidated quaternary sediments of widely differing grain size and during the past half century rapid socio economic development has created an increased demand for groundwater resources understanding the hydrogeochemical processes of groundwater and water quality is important for sustainable development and effective management of groundwater resources in the heihe river basin to this end a total of 30 representative groundwater samples were collected from different wells to monitor the water chemistry of various ions and its quality for irrigation chemical analysis shows that water presents a large spatial variability of chemical facies so42 hco3 so42 cl and cl so42 as groundwater flow from recharge area to discharge area the ionic ratio indicates positive correlation between the flowing pairs of parameters cl and na r 0 95 so42 and na r 0 84 hco3 and mg2 r 0 86 and so42 and ca2 r 0 91 dissolution of minerals such as halite gypsum dolomite silicate and mirabilite na2so4 10h2o in the sediments results in the cl so42 hco3 na ca2 and mg2 content in the groundwater other reactions such as evaporation ion exchange and deposition also influence the water composition the suitability of the groundwater for irrigation was assessed based on the us salinity laboratory salinity classification and the wilcox diagram the results show that most of the groundwater samples are suitable for irrigation uses barring a few locations in the dessert region in the northern sub basin

time dependent onshore tsunami response abstract while bulk measures of the onshore impact of a tsunami including the maximum run up elevation and inundation distance are important for hazard planning the temporal evolution of the onshore flow dynamics likely controls the extent of the onshore destruction and the erosion and deposition of sediment that occurs however the time varying dynamics of actual tsunamis are even more difficult to measure in situ than the bulk parameters here a numerical model based on the non linear shallow water equations is used to examine the effects variations in the wave characteristics bed slope and bottom roughness have on the temporal evolution of the onshore flow model results indicate that the onshore flow dynamics vary significantly over the parameter space examined for example the flow dynamics over steep smooth morphologies tend to be temporally symmetric with similar magnitude velocities generated during the run up and run down phases of inundation conversely on shallow rough onshore topographies the flow dynamics tend to be temporally skewed toward the run down phase of inundation with the magnitude of the flow velocities during run up and run down being significantly different furthermore for near breaking tsunami waves inundating over steep topography the flow velocity tends to accelerate almost instantaneously to a maximum and then decrease monotonically conversely when very long waves inundate over shallow topography the flow accelerates more slowly and can remain steady for a period of time before beginning to decelerate these results indicate that a single set of assumptions concerning the onshore flow dynamics cannot be applied to all tsunamis and site specific analyses may be required

sedimentary heterogeneity and petrophysical characterization of barremian tsunami and barrier island inlet deposits the aliaga outcrop as a reservoir analogue galve sub basin eastern spain abstract the present study examined two sandstone deposits in the aliaga outcrop as a reservoir analogue over a distance of 200 m long and attempted to establish a correlation between sand facies and the petrophysical properties of the sandstones in order to investigate the reservoir heterogeneity the aliaga reservoir analogue represents the upper part of camarillas fm deposited during the barremian synrift phase of the galve sub basin iberian basin spain it is characterized by a transitional sedimentary interval from sandy dominant deposits to carbonate dominant deposits which were deposited under the same palaeoenvironmental conditions in relation to systems of back barrier sedimentation the description of the aliaga outcrop provided here consists of lithological descriptions of two sandstone deposits a tsunami and a barrier island inlet at both mesoscopic decimetres to tens of metres and microscopic scales millimetres to centimetres both deposits recognized at the basin scale were described in terms of sand grain size sand sorting and cementation further cores were drilled along outcrop to collect samples for porosity and permeability measurements both sandstone reservoirs are the result of different sedimentary processes that determined facies characteristics as the different petrophysical properties observed in these deposits consequently the sedimentary process controls the heterogeneity of the sandstones facies and thus the sand heterogeneity controls the distribution of the petrophysical properties the classification of sand facies in terms of sand sorting seems to be more appropriate for describing sand heterogeneity accordingly petrophysical parameters in both deposits were also influenced by sand sorting the sand facies and petrophysics heterogeneity of the described deposits can be hierarchically ordered first order heterogeneity is related to the basin scale second order heterogeneity is related to genesis and the conditions of sediment deposition and third order heterogeneity is related to synsedimentary faults and or post sedimentation events

coping between crises early triassic early jurassic bivalve diversity dynamics abstract the triassic is bounded by two of the most severe biotic crises but nevertheless this time was for bivalves both a recovery and a diversification period and a moment to fully exploit some of their evolutionary novelties just how and when this was achieved is analyzed in this paper which covers induan to sinemurian bivalve diversity based on a newly compiled database taxonomic diversity and ecospace dynamics are examined separately diversity and evolutionary rates were assessed extinction selectivity was tested using a resampling algorithm and cohort analysis was used to study extinction patterns during the early triassic most bivalve genera were survivors from the permian and they were mainly cosmopolitan epifaunal and semi infaunal endobyssate taxa reclined epifaunal and semi infaunal bivalves increased in diversity during the triassic but from norian on their diversity declined and they were strongly affected by the t j crisis although the triassic jurassic extinction strongly impacted bivalve taxonomic diversity it had little impact on bivalve ecologic diversity not a single bivalve life strategy was eliminated at the end of the triassic the present study does not support previous conclusions that infaunal bivalves suffered greater extinction than epifaunal ones during the t j extinction not all life strategies were equally affected by the extinction event being the deep infaunal burrowers positively selected bivalves with major energetic requirements seem to have been more affected with negative selectivity on fast shallow burrowers the ecologic diversity changes of bivalves during the late triassic and several adaptations of durophagous predators reflect the effects of increasing predation pressure and support a late triassic origin of the mesozoic marine revolution

a unique 4000 year long geological record of multiple tsunami inundations in the augusta bay eastern sicily italy abstract we present the geological evidence for a 4000 year long record of multiple tsunami inundations along the coast of the augusta bay eastern sicily and discuss its implications the research was carried out through a multi theme approach which benefited from an extraordinarily long historical record that we used to guide detailed geomorphologic and geologic surveys coring campaigns and laboratory analyses two sites named the augusta hospital and priolo reserve were selected and investigated in detail along the 25 km long coastline of augusta bay we found evidence for six possibly seven tsunami deposits three of them may be tentatively associated with the 1693 and 365 ad ionian sea historical tsunamis and the 3600 bp santorini event the other three possibly four deposits are evidence for unknown paleo inundations dated at about 650 770 ad 600 400 bc and 975 800 bc at augusta hospital site and 800 600 bc at priolo reserve site we use these ages to extend further back the historical record of tsunamis available for this coastal area the exceptional number of tsunami deposits found with this study allowed us to derive an average geologic tsunami recurrence interval in the augusta bay of about 600 years for the past 4 ka conversely the historical tsunami data for the past millennium suggest an average tsunami recurrence interval of about 250 years this difference in the average recurrence intervals suggests that only the strongest inundations may leave recognizable geological signatures at the investigated sites i e the evidence for the 1908 and 1169 tsunamis is missing but also that the geomorphological setting of the site and its erosional depositional history are critical aspects for the data recording thus an average recurrence interval derived from the geological record should be considered as a minimum figure the identification and age estimation of tsunami deposits represent a new and independent contribution to tsunami scenarios and modeling for coastal hazard assessment in civil protection applications furthermore our study cases provide new elements on tsunami deposit recognition related to exceptionally large events that occurred in the aegean sea

the 2009 jiweishan rock avalanche wulong china precursor conditions and factors leading to failure abstract this study investigates the predisposing geological and anthropogenic factors and indicative precursors preceding the fatal 5 june 2009 jiweishan rock avalanche it began as a rockslide and transformed into a rock avalanche that killed 74 people and caused major property loss due to misdiagnosis of the failure mode and underestimation of volume and travel distance besides topography structure and stratigraphy that favoured failure mining below the failed rock mass had changed the state of stress and altered groundwater flow the anthropogenic factors caused deformation and accelerated failure of the slope and therefore were important contributions cracks and a karstic zone had developed along regional joints and defined several boundaries of the failed rock mass furthermore a 2 m wide crack developed since 1958 revealed a potential basal failure surface at the contact between karstic limestone and an underlying pre sheared thin shale aquiclude increasing magnitude and frequency of rockfalls and tension cracks at the front end of the sliding block appeared three days before the event and implied the likely movement direction of the sliding rock mass these could have warned of a developing giant failure topography included a large elevation difference between the toe of the failure surface and the cliff base a narrow valley to channel debris and the steep gradient of the downstream tiekuang creek could have suggested that failure might lead to a rapid and long runout rock avalanche however access to the densely vegetated source area before the failure was difficult and local investigators did not have all of the evidence that might have led them to recognize that potential danger was more than continuing rockfalls

geologic factors controlling co2 storage capacity and permanence case studies based on experience with heterogeneity in oil and gas reservoirs applied to co2 storage a variety of structural and stratigraphic factors control geological heterogeneity inferred to influence both sequestration capacity and effectiveness as well as seal capacity structural heterogeneity factors include faults folds and fracture intensity stratigraphic heterogeneity is primarily controlled by the geometry of depositional facies and sandbody continuity which controls permeability structure the permeability structure in turn has implications for co2 injectivity and near term migration pathways whereas the long term sequestration capacity can be inferred from the production history examples of gulf coast oil and gas reservoirs with differing styles of stratigraphic heterogeneity demonstrate the impact of facies variability on fluid flow and co2 sequestration potential beach and barrier island deposits in west ranch field in southeast texas are homogeneous and continuous in contrast seeligson and stratton fields in south texas examples of major heterogeneity in fluvial systems are composed of discontinuous channel fill sandstones confined to narrow sinuous belts these heterogeneous deposits contain limited compartments for potential co2 storage although co2 sequestration effectiveness may be enhanced by the high number of intraformational shale beds these field examples demonstrate that areas for co2 storage can be optimized by assessing sites for enhanced oil and gas recovery in mature hydrocarbon provinces

early triassic intertidal subtidal patterns of sedimentation along the southern margins of the tethyan seaway jordan abstract the early triassic dardur formation exposed along the northeastern margin of the dead sea area comprises some 63 m of siliciclastic and carbonate rocks arranged in two coarsening upward sequences each sequence begins with a heterolithic facies silty shale dolomite and marlstone and terminates with a sandstone facies the occurrence of mixed carbonate dominated clastic coarsening upward facies sequences containing pelecypode and ostracode fossils and trace fossils is attributed to deposition in a tidally dominated environment bedload traction transport was responsible for deposition of the sandstone facies in a permanently submerged shallow subtidal zone whereas the presence of small scale interference oscillation ripple marks tidal rhythmites and mudcracks in the heterolithic facies indicate deposition under more fluctuating intertidal conditions the organization of heterolithic and sandstone into vertically stacked coarsening upward marine facies sequences is attributed to a deepening upward trend from intertidal to subtidal conditions in response to a series of minor local transgressions and regressions along the southern margins of the tethyan seaway during early triassic times

extensional fault control on the sedimentation patterns in a continental rift basin el castellar formation galve sub basin spain in the galve sub basin the sedimentary record of the upper hauterivian lower barremian el castellar formation is divided into two stages by a marlstone interval with gypsum stage 1 shows a great variety of subenvironments and facies alluvial palustrine and lacustrine whereas in stage 2 an extensive shallow carbonate lake developed sedimentation was controlled by a system of south dipping ene wsw listric normal faults laterally bounded by nnw sse steeper transfer faults faults controlled sedimentation from a basin scale basin margins and main characteristics and evolution of sediments to a regional and a local scale thickness and facies distribution of the synrift series as well as the location and evolution of lakes and minor alluvial fans the changes between stages 1 and 2 are related to the passing from an independent movement of faults to the movement of all the extensional faults as a whole at a sole detachment level the interval with gypsum was caused by underground water flow changes associated with the interrelation and connection of the faults in the transition period these changes have been correlated with the transition from the rift initial stage to the rift climax stage which took place in the hauterivian barremian transition

stratigraphic evidence for shear in structural development of the triassic levant margin new borehole data on the epicontinental to deep marine transition in israel abstract triassic tectonic movements that include shear along a significant portion of the levant margin are evidenced from microfacies analysis of material recovered from the asher atlit 1 ga ash 2 meged 2 devora 2 and ramalla 1 onshore boreholes seismic studies showed that structural lineaments attributed to early mesozoic extension underlie coastal and central israel trending ne sw beneath southern israel and sub parallel to the then extensional palmyride basin of syria a more curved trend approximately nnw sse lies to the north beneath central israel coast parallel sedimentary domains formed above these lineaments which constitute the newly formed passive margin of the levant coast in the triassic the sedimentary history of these domains indicates that some were linked to each other and others disconnected the relative vertical movement between one domain and another is explained by activation of transpressional and trans tensional shear movements on the underlying curved faults these subordinate vertical movements also created the discontinuous barriers and small subsiding basins that separate the epicontinental sedimentary domain from the open tethys causing partial restriction necessary for the intermittent development of thick evaporites in the internal domains alternating with a regionally suppressed carbonate system this zone is here named the onshore levant margin shear zone olmsz shear was invoked theoretically in a number of models for the tectonic evolution of the eastern mediterranean as part of a neotethyan opening system this paper provides rock based evidence for such shear applicable to 20 of the eastern levant margin in the triassic

heterogeneity patterns of quaternary glaciofluvial gravel bodies sw germany application to hydrogeology abstract the architecture of sedimentary bodies determines the heterogeneity of many aquifers thus for environmental risk assessment and quantification of clean up efficiencies determination of the spatial distribution of hydraulic properties is required in this study outcrop analogues of glaciofluvial gravel bed deposits are used for a process based analysis of sedimentary heterogeneities which in turn are transformed into hydraulic parameters three scales of heterogeneities are distinguished a the lithofacies scale is formed by unique transport and depositional processes that form the fundamental building blocks hydrofacies types b the depositional element scale shows distinct geometrical characteristics internal structure and bounding surfaces and determines the local distribution of lithofacies and hence the correlation structure of permeabilities c the architectural scale of gravel bodies is formed by the stacking of depositional elements which is controlled by the dynamics of aggrading paleofluvial systems comparison of numerous gravel pits in sw germany revealed three major architectural patterns of glaciofluvial gravel bodies that can be distinguished statistically by the preservation of depositional elements as well as the frequency of lithofacies types the facies analysis results in three conceptual facies models of proglacial river systems which are regionally classified as main intermediate and minor discharge types based on calculated and laboratory measured hydraulic properties of the various lithofacies types detailed outcrop wall maps were digitized into polygons of defined hydrofacies types by using the gis system arc info the two dimensional fields of hydraulic properties were then transferred into a numerical model of groundwater flow modeling results clearly illustrate that the three heterogeneity patterns of gravel bodies also have distinguishable hydraulic response characteristics

numerical models of tsunami sediment transport current understanding and future directions abstract researchers who study tsunami deposits share common ultimate goals of their work which are to better assess the magnitude information of paleotsunamis and to contribute to the assessment of future tsunami risks numerical modeling of tsunami sediment transport is an important piece of interdisciplinary research that fills the gap between geological studies and practical utilization of tsunami deposits forward and inverse numerical models that address tsunami transport of sand and boulders have been developed over the last two decades forward models are capable of delineating the time evolution of tsunami hydrodynamics sediment transport and the resulting morphological changes associated with erosion and deposition inverse models estimate tsunami characteristics such as flow speed and depth from deposits numerical modeling can be used not only to quantify paleotsunamis but also to enhance our understanding of tsunami sedimentology and hydrodynamics to make progress towards the ultimate goal of improved tsunami risk assessment development of an in depth mutual understanding between modelers and geologists of the advantages limitations and uncertainties in both numerical modeling and geological records is an important challenge

lithofacies and cyclicity of mohilla evaporite basins on the rifted margin of the levant in the late triassic makhtesh ramon southern israel marine connected basins with evaporites occur beneath most extensional continental margins that originated at low latitudes and often are of major economic significance cyclicity in the evaporite lithofacies reflects the degree of restriction of the basin overprinted by sea level changes and caused by structural movements in the barrier region whether by fault block rotation footwall uplift or hanging wall subsidence in both extensional and compressional basins the upper triassic evaporites of the ramon section in southern israel model cyclic sedimentation in such environments the mohilla formation is a carbonate evaporate siliciclastic succession of carnian age that fills a chain of basins extending along the levant margin from southern israel to jordan and syria the basins developed in half grabens adjacent to normal faults that formed during a period of regional extension evaporites of this formation are well exposed in outcrops at makhtesh ramon the southernmost of these basins the m2 member of the mohilla formation is composed of 42 sub metre cycles of alternating dolostone gypsum and calcareous shales field and microfacies analysis showed these cycles to conform mostly to restricted shallow and marginal marine environments spatially limited by the uplifted shoulders of the half graben systems a total of 10 facies types belonging to six depositional environments have been identified from stacking patterns and analysis of bed to bed change cycles can be categorized into three groupings i low frequency exposure to exposure cycles that developed under eustatic or climate control ii high frequency deepening shallowing upward cycles characterized by gradual transitions due to short term sea level or runoff event oscillations possibly referable to orbital forcing and iii high frequency shallowing upward cycles characterized by abrupt transitions attributable to sporadic tectonic events affecting accommodation space or barrier effectiveness the way facies and cycling of the sedimentary environments was deciphered in the mohilla evaporite basin can be used to unravel the genesis of many other evaporite basins with barriers of tectonic origin

triassic climates state of the art and perspectives abstract the climate of the triassic period was characterized by a non zonal pattern dictated by a strong global monsoon system with effects that are most evident in the tethys realm this strong monsoonal regime is related to the aggregation of the pangaean supercontinent which by triassic time was already completed climate oscillations existed within this framework the harsh hot house climatic conditions that characterized the late permian and perhaps precipitated the end permian mass extinction were probably maintained during the early triassic and may account for the impoverished but distinctive faunal and floral lower triassic associations although metazoan reef builders were probably the most affected group carbonate production remained high at least in the western tethys realm the middle triassic was characterized locally by humid episodes although their geographical distribution has yet to be clarified the carnian pluvial event marks an episode of increased rainfall documented worldwide was the most distinctive climate change within the triassic different hypotheses have been proposed for its causes changes of atmospheric or ocean circulation driven by plate tectonics a peak of the global monsoon due to maximum continent aggregation or triggering by the eruption of a large igneous province subsequently the late carnian and norian seem to have been climatically stable although minor climatic changes have recently been described even from this time period finally the end triassic extinction event is also associated with climate change specifically warming and increased rainfall but this evidence comes mostly from the northern parts of the central atlantic magmatic province and the global pattern of climate change at the triassic jurassic boundary has still to be resolved many facets of triassic climate are intriguing and deserve further research however palaeoclimate studies on the triassic have so far been carried out only locally with different proxies those proxies will require inter calibration in order to depict correctly the temporal and geographical patterns of triassic climate

microbially mediated carbonate precipitation in a hypersaline lake big pond eleuthera bahamas microbial metabolism impacts the degree of carbonate saturation by changing the total alkalinity and calcium availability this can result in the precipitation of carbonate minerals and thus the formation of microbialites here the microbial metabolic activity the characteristics and turnover of the extracellular polymeric substances and the physicochemical conditions in the water column and sediments of a hypersaline lake big pond bahamas were determined to identify the driving forces in microbialite formation a conceptual model for organomineralization within the active part of the microbial mats that cover the lake sediments is presented geochemical modelling indicated an oversaturation with respect to carbonates including calcite aragonite and dolomite but these minerals were never observed to precipitate at the mat water interface this failure is attributed to the capacity of the water column and upper layers of the microbial mat to bind calcium a layer of high mg calcite was present 4 to 6 mm below the surface of the mat just beneath the horizons of maximum photosynthesis and aerobic respiration this carbonate layer was associated with the zone of maximum sulphate reduction it is postulated that extracellular polymeric substances and low molecular weight organic carbon produced at the surface i e the cyanobacterial layer of the mat bind calcium both aerobic and anaerobic heterotrophic microbes consume extracellular polymeric substances each process accounting for approximately half of the total consumption and low molecular weight organic carbon liberating calcium and producing inorganic carbon the combination of these geochemical changes can increase the carbonate saturation index which may result in carbonate precipitation in conclusion the formation and degradation of extracellular polymeric substances as well as sulphate reduction may play a pivotal role in the formation of microbialites both in marine and hypersaline environments

significance of subtidal microbial deposits in shark bay australia abstract microbial deposits at shark bay australia constitute one of the largest and most diverse modern occurrences around the world the microbial carbonate system has developed in response to environmental change from near open marine into restricted embayment with hypersalinity and high evaporation bacterial sediments started depositing at about 2000 years bp after the holocene maximum flooding of sea level about 6800 years bp due to increasing salinity as the sea level fell by about 2 5 m within the holocene highstand system tract the extent and types of subtidal microbial substrate in this world heritage area have not previously been fully systematically mapped and described here we document the importance of subtidal microbial deposits occupying as much as 10 times the occurrence area of the intertidal microbial mats and stromatolites and demonstrate that deeper structures have a cerebroid external morphology with a non laminated internal fabric subtidal structures contain consistently different internal fabrics with carbonate grains and fragments interbedded with aragonitic micrite arranged in millimetric laminae or sub spherical patches which display fabrics such as well laminated smooth coarse laminated wavy colloform sub laminar to irregular with voids and biofragments of bivalves microbial pavement irregular clotted pustular and non laminated cerebroid constituting carbonate sediment with stromatolitic facies smooth and colloform thrombolitic facies pustular and cryptomicrobial non laminated cerebroid and microbial pavement each microbial structure grows in specific settings according to water depth msl with cerebroid build ups commonly occurring between 1 and 2 5 m and microbial pavement extending as deep as 6 m because of the late holocene sea level fall microbial structures often record in their internal features a shallowing up carbonate cycle these newly documented extensive subtidal microbial structures with distinctive morphologies and fabrics have importance as modern occurrences and provide potential analogues for understanding ancient microbial systems and environments

facies and petrophysical modelling of a thick lower cretaceous tsunami deposit in e spain up scaling from sample to outcrop scales abstract the tsunami deposit up to 3 m thick of the cretaceous camarillas formation in the galve sub basin eastern spain is characterized by a large lateral extent 35 km 2 and facies uniformity consisting in fine to coarse subarkosic arkosic sandstones at the scale of outcrop observation different lithofacies were distinguished and related to sedimentation processes sand facies distribution conditioned the facies heterogeneity at both mesoscopic or outcrop scales 10 1 10 1 m scale and sample scale 10 3 10 2 m the sample features were up scaled to that of a facies model using probability functions and variograms as well as to outcrop scale data geometry and size of facies distribution and it showed a good correlation with the facies distribution at the outcrop porosity is strongly correlated to permeability and the pairs of porosity and permeability values fall into the global hydraulic element ghes 5 so that they can be up scaled into reservoir models in terms of hydraulic properties from data analysis no apparent link between sand sorting and porosity and permeability values was observed the petrophysical models which were independent of facies models were up scaled taking into account the porosity and permeability values from sample data and the statistical analysis of their distribution along the outcrop the permeability model was carried out as a function of porosity by applying a linear relation which simplified the modelling process and discarded permeability uncertainties linked to facies distribution in the deposit in spite of different source data the petrophysical models show a distribution of lower and higher values that resembles the facies model consequently our modelling results clearly suggest the link of facies type and their grain size distributions with the petrophysical properties into the deposit consistency between facies and petrophysical models and outcrop scale observations make it possible to extrapolate to other deposits related to similar sedimentary processes

the unusual sedimentary rock record of the early triassic a case study from the southwestern united states abstract sedimentary systems as well as the earth s biota changed dramatically following the end permian mass extinction this global sedimentological transformation is reflected in the widespread occurrence of flat pebble conglomerates subtidal wrinkle structures microbialites and carbonate seafloor fans in various lower triassic sections as a case study a facies analysis of the lower triassic virgin limestone member of the moenkopi formation and the middle and upper members of the union wash formation southwestern united states was conducted and all unusual facies were documented within a palaeoenvironmental framework the occurrence of the flat pebble conglomerates and wrinkle structures is significant because these reflect a long term reduction in vertical bioturbation in the case of the subtidal microbialites and carbonate seafloor fans their formation is linked to an increase in alkalinity the presence of these facies in the uppermost lower triassic strata of the southwestern united states indicates that reduced levels of infaunal bioturbation as well as and perhaps a consequence of unusual ocean chemistry extended for 5 6 million years after the end permian mass extinction suggesting that depositional environments as well as the biota were significantly affected by the extinction event

a thick tethyan multi bed tsunami deposit preserving a dinosaur megatracksite within a coastal lagoon barremian eastern spain abstract a thick multiple bed tsunami deposit consisting of sandstones and conglomerates has been discovered and investigated in the camarillas formation 130 6 128 4 ma barremian age in eastern spain the tsunami deposit is interbedded within red mudstones deposited in mud flats of a back barrier system it crops out along 7 km in length and at its base a great number of dinosaur tracks assigned to sauropods ornithopods and theropods have been preserved as natural casts then constituting an exceptional regional megatracksite associated with tsunami deposits on the basis of sedimentological features and the lateral and vertical architecture of the involved lithofacies up to five couplets of inflow backflow deposits formed by a tsunami wave train have been recognized overlying the tracks although sedimentation mainly took place during backflow currents inflows led to the removal of sand from a fronting barrier island and the rip up of lagoonal carbonate and clay pebbles depositing them in the protected back barrier lagoon its unusually great thickness is interpreted among others as being the result of the filling of the previous low topography of the back barrier lagoon

characteristics distribution and morphogenesis of subtidal microbial systems in shark bay australia abstract the distribution nature and extent of microbial deposits in hamelin pool shark bay have been investigated and mapped with emphasis on the occurrence external morphologies internal fabrics constructional mechanisms microbial communities growth rates and sediment associations in the intertidal and previously little researched subtidal zone detailed georeferenced substrate mapping revealed extensive subtidal microbial deposits occupying approximately 300 km 2 of the total holocene 1400 km 2 area of hamelin pool the microbial pavement covers 227 km 2 of the subtidal substrate that together with columnar structures reveals a subtidal microbial habitat which occupies an area 10 times larger than the area of the intertidal deposits microbial carbonate is composed of aragonite 80 98 that reveals high positive values of 13 c 4 46 to 5 88 and 18 o 3 06 to 3 88 as a characteristic of the highly evaporative environment with extensive microbial activity oldest dated heads are 1915 and 1680 14 c years bp and the overall system was deposited in two stages the first between 2000 and 1200 and the last from 900 years bp to the present slow growth rates vary from less than 0 1 mm year to 0 5 mm year different internal fabrics were constructed according to their position in relation to the littoral zone by distinct microbial communities and lateral fabric relations have been established evidence of shallowing upward fabric sequences of microbial origin reflects relative falling sea levels during the late holocene and is likely useful in ancient environmental interpretation a sequence of events and mechanisms are described emphasizing differences between the stromatolitic thrombolitic and cryptomicrobial deposits in shark bay the new substrate map and depositional history for this distinctive and peculiar microbial habitat establish the significance of subtidal structures and emphasize the geoscientific importance of hamelin pool especially with respect to early life studies and ancient analogues for understanding microbial activity deposit characteristics fenestral fabrics and distribution

palaeosols of the lower jurassic mishhor and ardon formations laterite derivative facies makhtesh ramon israel the lower jurassic sequence exposed at makhtesh ramon in the south western negev of israel comprises cyclic fluviatile sediments derived almost exclusively from the reworking of an older laterite terrain a succession of palaeosols having the characteristics of modern red brown earths has developed during periods of sub aerial exposure upon the fine grained overbank sediments a marked seasonal palaeoclimate with accompanying poor sub surface drainage conditions and some stagnation of ground water is reflected by the distribution and mottling patterns of the iron minerals with varying degrees of hydration precipitation of illuviated carbonate and sulphate minerals and the development of soil microrelief a complex history of pedogenesis and ground water alteration is shown by the rapid lateral facies change within this sequence into one dominated by high alumina flint clay and bauxite relict pedogenetic and sedimentological textural features of the combined palaeosol fluviatile sequence have been identified and mapped within the flint clay bauxite lithologies these features include irregular voids produced by solution of pedogenic sulphate nodules slickensided curviplanar surfaces of soil microrelief and depositional bedding the field relationships of these relicts indicate the overprinting of a younger chemical weathering event giving rise to the high alumina flint clay and bauxites the geometric shape of the upper bounding surface of the bauxite alteration zone is irregular and has an intrusive character with respect to the younger overlying unaltered sediments this together with abrupt changes in mottling patterns near the contact zone and subtle changes in mineralogy from a bauxitic assemblage at depth to one containing mixed layer clay minerals and carbonates nearer the contact leads to the conclusion that the later stages of chemical weathering occurred within a confined system where ground water movements were induced by intake of underlying aquifers

environmental geochemistry and quality assessment of mine water of jharia coalfield india a long mining history and unscientific exploitation of jharia coalfield caused many environmental problems including water resource depletion and contamination a geochemical study of mine water in the jharia coalfield has been undertaken to assess its quality and suitability for domestic industrial and irrigation uses for this purpose 92 mine water samples collected from different mining areas of jharia coalfield were analysed for ph electrical conductivity ec major cations ca2 mg2 na k anions f cl hco3 so4 2 no3 dissolved silica h4sio4 and trace metals the ph of the analysed mine water samples varied from 6 2 to 8 6 indicating mildly acidic to alkaline nature concentration of tds varied from 437 to 1 593 mg l 1 and spatial differences in tds values reflect the variation in lithology surface activities and hydrological regime prevailing in the region so4 2 and hco3 are dominant in the anion and mg2 and ca2 in the cation chemistry of mine water high concentrations of so4 2 in the mine water of the area are attributed to the oxidative weathering of pyrites ca mg so4 and ca mg hco3 are the dominant hydrochemical facies the drinking water quality assessment indicates that number of mine water samples have high tds total hardness and so4 2 concentrations and needs treatment before its utilization concentrations of some trace metals fe mn ni pb were also found to be above the desirable levels recommended for drinking water the mine water is good to permissible quality and suitable for irrigation in most cases however higher salinity residual sodium carbonate and mg ratio restrict its suitability for irrigation at some sites

the triassic of the southern margin of the tethys in the levant and its correlation across the jordan rift valley the triassic of the levantine region consists of four sedimentary cycles i scythian lower anisian ii early upper anisian iii late upper anisian carnian iv late carnian norian

a late permian coral reef complex south kitakami terrane japan abstract the early late permian kubergandian to midian iwaizaki limestone of the south kitakami terrane situated in northeast japan represents a coral reef complex which was formed on a faulted bank in an active continental margin the reef building organisms include cerioid and dendroid rugose corals a fasciculate tabulate coral and solenoporacean algae as constructors calcisponges bryozoans and crinoids as bafflers and tubiphytes archaeolithoporella and cyanobacteria as binders the biotic composition is more diverse than the other coeval reefs characterized by the existence of an obvious framework this reef is similar to the recent coral reefs and unique among late permian reefs most of which are mainly formed by calcisponges and calcareous algae the distribution of late permian reefs is closely related to the palaeoclimate coral reefs were developed mainly around the south china and indochina continental masses between the tethys sea and the panthalassa ocean in the tropics while calcisponge reefs and tubiphytes algal crust reefs were common in tropical to subtropical regions and stromatolite bryozoan reefs developed in arid areas the gradational distribution of late permian organic reefs including localized development of coral reefs were probably caused by decreasing of the glaciers and changing of the ocean current systems

tectonic map and geologic evolution of syria the role of gis this paper was published in the journal the leading edge by the society of exploration geophysicists seg retains the copyright to this paper see also http www edge online org http atlas geo cornell edu syria brew tle 2000 html

inflow and outflow facies from the 1993 tsunami in southwest hokkaido abstract we describe in detail the sedimentary facies provenance and grain size distributions of the 1993 tsunami deposits in the lower reaches of usubetsu river only two lithofacies were recognized a gravel lobe facies glf and a sand sheet facies ssf the gravel lobe facies was deposited rapidly by a hydraulic jump in contrast the sand sheet facies which contains both current ripples and dunes was deposited by a traction current under subcritical flow conditions we identified four stratigraphic units unit 1 unit 2 unit 3 and unit 4 in ascending order we interpreted units 1 and 2 as having been deposited by the inflow and outflow events of the first run up and units 3 and 4 by the inflow and outflow events of the second run up respectively units 3 and 4 were more widely distributed and coarser grained than units 1 and 2 because the second run up was larger than the first run up furthermore unit 4 was more widely distributed than unit 3 because the outflow eroded the inflow deposits grain size distributions of the inflow and outflow deposits were clearly different unit 4 deposits had a peak at 2 5 phi p 1 population in contrast unit 3 deposits had a bimodal distribution with peaks at 0 5 1 5 phi p 2 population and at 2 5 phi p 1 population a comparison of the tsunami deposits with other sedimentary deposits near the study area showed that the tsunami deposits were mainly derived from the seabed at depths below 5 5 m in the offshore area where the marine sands are about 2 2 5 phi in size and thus are the source of the p 1 population the p 2 population is derived from coarse 0 5 2 phi fluvial materials eroded during the tsunami run up according to our calculations benthic foraminiferal tests were entrained from the comparatively deep seabed at depths up to 100 m during the tsunami run up and included in the tsunami deposits

permian triassic boundary interval in the abadeh section of iran with implications for mass extinction part 1 sedimentology the uppermost permian strata of the abadeh section in iran consist of 56 m of skeletal limestone abadehian that grades upward into 18 m of grey bioturbated lime mudstone djulfian which in turn grades upward to 18 m of red nodular wackestone dorashamian containing an abundant pelagic fauna the overlying lowermost triassic includes two enigmatic layers at its base immediately above the boundary is a 1 m thick layer of inorganically precipitated synsedimentary carbonate cement the cement is composed of 10 20 cm long crystals oriented either perpendicular to the bedding or as dome shaped features resembling botryoids about 0 5 m of wackestone overlies the cement layer the second layer is a 1 5 m thick grainstone overlying the cement horizon and consists of recrystallised spherical grains ooids or peloids the remainder of unit a is composed of 100 m of grey bioturbated to nodular lime mudstone the lithofacies succession of the uppermost permian is interpreted to represent deposition under increasing water depth related to rising of relative sea level which led to drowning of the carbonate platform to below storm wave base sedimentologic characteristics lithology wide distribution and slow sedimentation rates indicate that strata immediately below the permian triassic p t boundary dorashamian interval were deposited in deep oxygenated waters the enigmatic lowermost triassic synsedimentary carbonate cement and grainstone layers are interpreted to have been deposited in shallow waters indicating a rapid and major drop in relative sea level at the end of permian time in this area followed by a relative sea level rise during the earliest triassic precipitation of synsedimentary cement immediately above the p t boundary in iran and elsewhere south china suggests a global change in ocean chemistry one possible explanation is that dissolved calcium and bicarbonate concentrations in seawater increased sufficiently to promote spontaneous carbonate precipitation a rare event in the phanerozoic but common during precambrian time alternatively a massive heating event could have resulted in co2 degassing and decreases in oceanic carbonate solubility both leading to inorganic synsedimentary carbonate precipitation inorganic precipitation of synsedimentary carbonate cement may indicate that biochemical production of carbonate was halted due to the p t boundary events our study indicates that shallow and moderately deep waters during the latest permian were well oxygenated in the open ocean setting of the central tethys sea in iran therefore p t mass extinction scenarios that invoke upon widespread marine anoxia should be viewed with caution

microbial serpulid build ups in the norian rhaetian of the western mediterranean area ecological response of shelf margin communities to stressed environments microbial serpulid communities are the main reef builders of most norian rhaetian carbonate platforms of italy they represent minor yet significant communities in the shallow western tethys in contrast with the highly diversified sponge and coral dominated dachstein reefs widespread from eastern alps to australia the microbial serpulid build ups are systematically associated with narrow intraplatform troughs and developed on the outer margin upper slope area under marine conditions unsuitable for the development of coralgal reefs the development of these settings can be related to transtensional tectonics affecting an elongate belt which was roughly parallel to the piedmont ligurian ocean spreading axis during the jurassic dysoxic and mesosaline waters are the main cause of the success of the norian microbial serpulid build ups whereas from the late norian to the rhaetian eutrophication and climate change control their distribution these environments acted during norian rhaetian times as refuges where opportunitistic organisms could survive and build frameworks during a period otherwise dominated by coralgal reefs

dolomite formation in the shallow seas of the alpine triassic the alpine triassic units of switzerland northern italy and western austria offer an extensive geological archive in which the enigmatic process of dolomite formation can be studied in a palaeoenvironmental context recent studies clearly demonstrate that large amounts of the alpine triassic dolomites are late diagenetic or hydrothermal nevertheless as part of multiple generations of diagenetic overprint some generations of fine crystalline ca rich dolomite appear strictly confined to their depositional facies and show signs of very early formation at surface temperatures in specific ancient depositional environments in this review three cases of alpine triassic dolomites are discussed where dolomite rocks may have formed during or soon after sedimentation the sedimentary facies indicate contrasting palaeoenvironmental conditions and hence document three different possible processes of dolomite formation i in the dolomite mountains northern italy dolomite beds of the partly isolated middle triassic anisian ladinian latemar platform are confined to the very top of shallowing upward lagoonal facies cycles ii dolomite beds of the san giorgio basin southern switzerland an intra platform basin that opened during the anisian ladinian transition are associated with organic carbon rich shales which were deposited in a deeper water environment under anoxic conditions iii in the entirely dolomitized platform facies of the dolomia principale hauptdolomit formation a very early generation of fine crystalline dolomite occurs in the shallowest part of evaporative peritidal cycles this platform extended over thousands of square kilometres along the tethys margin during the late triassic carnian and norian and large amounts of carbonate were deposited under hypersaline sabkha like conditions representing three distinct depositional environments these three different triassic systems show features in common with several dolomitization models developed from the study of modern dolomite forming environments for example the sabkha model the evaporative lagoon lake model the organogenic model and the microbial model although these actualistic models may be applicable to reconstruct the palaeoenvironmental conditions during dolomite formation dolomite forming processes during the triassic were apparently quite different from the modern world in terms of distribution and scale recent developments in stable isotope geochemistry and high resolution geochemical probing offer the possibility to make better reconstructions of triassic palaeoceanographic conditions and suggest a non actualistic approach to better understand dolomite formation during the triassic

large perturbations of the carbon cycle during recovery from the end permian extinction high resolution carbon isotope measurements of multiple stratigraphic sections in south china demonstrate that the pronounced carbon isotopic excursion at the permian triassic boundary was not an isolated event but the first in a series of large fluctuations that continued throughout the early triassic before ending abruptly early in the middle triassic the unusual behavior of the carbon cycle coincides with the delayed recovery from end permian extinction recorded by fossils suggesting a direct relationship between earth system function and biological rediversification in the aftermath of earth s most devastating mass extinction

platform to shelf edge transect triassic of northern israel north arabian plate abstract a transect of the middle to late triassic from the epicontinental belt to the shelf edge of the north arabian margin is presented based on new data from two boreholes in northern israel two sedimentary systems are encountered along this traverse the inland meged 2 borehole represents the seaward extension of the epicontinental belt with shallow to deep water carbonates salina evaporites and basinal shales while ga ash 2 on the levant margin was positioned on an isolated platform separating the internal shelf basin system from the open tethys displaying a shallower range of facies that is free of evaporites proximal distal facies shifts are bundled into five low order lo t r cycles ranging from anisian pelsonian to norian each composed of numerous high order ho shallowing upwards cycles meged 2 paleoenvironments imply an interior basin trapping sediments of the epicontinental belt with numerous ho facies shifts indicating pulses of subsidence ga ash 2 contains lofer like peritidal cycles and a late anisian early carnian hiatus in place of the second lo cycle the two orders of cycling are controlled by extrabasinal regional or eustatic change and synsedimentary vertical movements the divergent sedimentary patterns of the late anisian late carnian can be attributed to nw se trans tensile movements impacting on earlier neotethyan extensional trends synsedimentary movements represented locally by uplift at ga ash 2 and subsidence at meged 2 controlled the influx of sea water into the epicontinental zone and consequently controlled the alternation of evaporite vs carbonate systems in the latest carnian early norian these facies belts become locked together forming a shallow high energy shelf this change reflects broad uplift and shifting of the locus of active differential movement into the levant basin

hydrogeochemical characterization and quality assessment of groundwater around umrer coal mine area nagpur district maharashtra india quality assessment as well as hydrogeochemical characterization of 45 representative groundwater samples around umrer coal mine area was undertaken the ph of the water lies in the normal range i e from 7 5 to 8 5 the electrical conductivity varies from 826 to 1 741 the total hardness varies from 289 to 1 302 and the tds values range from 528 6 to 1 114 2 mg l which reflects variation in lithology and thus the distinction in hydrogeological regime the cation chemistry is dominated by ca2 and mg2 while anion chemistry is dominated by cl and hco3 out of total ten hydrochemical facies the two dominant facies are mg ca hco3 37 7 and ca mg so4 hco3 17 7 the groundwater in the study area in general is useful for drinking and domestic use however it has marginal utility for irrigation purpose standard us salinity laboratory classification shows that water of the study area belongs to c2 s1 and c3 s1 classes the concentration of 9 trace elements analysed from 18 samples did not exceed the desirable limit

mesozoic extensional tectonics stratigraphy and crustal evolution during the alpine cycle of the eastern iberian basin abstract sequence stratigraphy subsidence analysis and the integration of the basin fill data allow to the identification of four successive evolutionary stages in the basins of the eastern iberian margin during mesozoic extension 1 triassic rift late permian hettangian 2 early and middle jurassic postrift sinemurian oxfordian 3 late jurassic and early cretaceous rift kimmeridgian middle albian and 4 late cretaceous postrift late albian maastrichtian the present day crustal structure of the eastern iberian range and evidence of its evolution are deduced from the analysis of a new gravity map and other geophysical data a regional gravity low along the iberian range is interpreted in terms of crustal thickening beneath the orogen as a result of the collision between the ebro block and the iberian plate during the paleogene the boundary between these blocks coincides with a magnetic lineament that is interpreted as an inherited signature of the thinning that occurred during mesozoic extension a geodynamic scenario for the crustal evolution of the eastern part of the iberian peninsula based on the evaluation of mesozoic extensional tectonics and an analysis of the available geophysical data includes three main successive evolutionary stages 1 1 mesozoic crustal thinning 2 2 paleogene crustal thickening 3 3 neogene crustal thinning based on new geological and geophysical arguments this study offers an alternative and a more complete geodynamic history of the eastern iberian basins related to the evolution of the iberian plate and the central north atlantic

environmental significance of microbialites in reef environments during the last deglaciation in situ microbialites occurring in reef rocks dredged between 80 and 130 m water depth on the modern fore reef slopes of tahiti and the marquesas islands yield ages ranging from 17 100 2900 to 4410 2250 years bp suggesting that they played a prominent role during the last deglacial sea level rise microbialites developed in both shallow and deep water depositional environments where they characterize various zones of the reef tracts reef crests upper reef slopes deep fore reef slopes reflecting contrasting scenarios of microbialite development involving reefal microbialites in shallow water settings and slope microbialites that formed in environments deeper than 10 20 m and extending down to more than 100 m reefal microbialites correspond to a late stage of encrustation of the dead parts of coral colonies or more commonly of related encrusting organisms red algae and foraminifers thus forming surface crusts slope microbialites generally form the ultimate stage of a biological succession indicating a deepening sequence whereby shallow water corals and associated encrusting organisms are replaced by deeper water assemblages of red algae and foraminifers before microbialite growth the precipitation of phosphatic iron manganese crusts and the deposition of planktonic micritic limestones on the microbialites characterize a deepening upward sequence the widespread development of microbialites in reef sequences from the last deglaciation characterizes a period of environmental degradation consequential on the rapid sea level rise and abrupt climatic changes of that time the reported biological succession reflects changes in water quality and especially an increase in nutrients in shallow water settings increased alkalinity and nutrient availability in interstitial waters were related to surface fluxes and terrestrial groundwater seepage while slope environments were exposed to continuous upwelling of nutrient rich deeper waters during the last deglacial sea level rise the age differences between corals and overlying slope microbialites range from 1600 to 8400 years based on high precision u series age measurements of both corals and microbialites and indicates that a significant time several thousand years elapsed between the development of the coralgal frameworks and the growth of slope microbialite crusts microbialites cannot be considered as part of the drowning event some 14 000 years ago that resulted in the demise of reef frameworks in the 90 110 m present depth range but are substantially younger

hydrochemistry of reservoirs of damodar river basin india weathering processes and water quality assessment water samples collected from the six reservoirs of damodar river basin in pre and post monsoon have been analysed to study the major ion chemistry and the weathering and geochemical processes controlling the water composition ca na and hco3 dominate the chemical composition of the reservoir water the seasonal data shows a minimum concentration of most of the ions in post monsoon and a maximum concentration in pre monsoon seasons reflecting the concentrating effects due to elevated temperature and increased evaporation during the low water level period of the pre monsoon season water chemistry of the reservoirs strongly reflects the dominance of continental weathering aided by atmospheric and anthropogenic activities in the catchment area higher concentration of so4 and tds in panchet durgapur and tenughat reservoirs indicate mining and anthropogenic impact on water quality the high contribution of ca mg to the total cations high concentration of dissolved silica relatively high na k tz ratio 0 3 and low equivalent ratio of ca mg na k suggests combined influence of carbonate and silicate weathering kaolinite is the possible mineral that is in equilibrium with the water implying that the chemistry of reservoir water favours kaolinite formation the calculated values of sar rsc and sodium percentage indicate the excellent to good quality of water for irrigation uses

gastropod evidence against the early triassic lilliput effect comment brayard et al 2010 1 assert that their study of late early triassic gastropods provides evidence against the post extinction lilliput effect regrettably their data provide no such evidence the lilliput effect as defined by urbanek 1993 2 is a quantifiable temporary decrease in the

ptb mass extinction and earliest triassic recovery overlooked new evidence for a marine origin of lower triassic mixed carbonate siliciclastic sediments rogenstein member germany abstract the central european permo triassic basin was land locked with occasional connections to the north pangaea shelf and tethys a thick sequence of siliciclastic fluvial and floodplain sediments separates the late permian marine carbonate evaporite cycles of the zechstein basin from marine middle triassic marls and carbonates of the germanic basin within this latest permian middle triassic siliciclastic interval the location of the permian triassic boundary ptb is difficult to recognize the first limestones after the ptb are induan mixed carbonate siliciclastic oolites and microbialites of the bernburg and calvorde formations untere buntsandstein group consensus emerged after a long lasting controversy that the carbonates of the so called rogensteine are the relics of an alkaline playa lake the idea of the marine genesis was finally rejected because of the obvious lack of calcified metazoans the existing depositional playa lake model will be tested using previously unconsidered data such as currently discussed early triassic recovery scenarios of marine benthic communities after the permian triassic mass extinction global patterns of early triassic carbonate production permian triassic tectono sedimentary evolution of northern pangaea and stable oxygen and carbon isotope data the rogenstein is interpreted as marine carbonate showing the characteristic features of marine carbonates of the early triassic recovery period calcified invertebrates are rare in many marine settings during the aftermath of the permian triassic mass extinction thin shells of the oolites resemble opportunistic bivalves flourishing in marine early triassic oceans the oolites and microbialites are the product of abiotic and biotically induced carbonate precipitation following the permian triassic mass extinction while biomineralisation is insignificant rogenstein microbialites look like marine early triassic microbial reefs the extraordinary size of the rogenstein ooids resembles marine neoproterozoic ooids the term anachronistic has been used in the literature to describe the similarities in the fabric and composition of early triassic and early palaeozoic neoproterozoic marine carbonates stable carbon isotopes of least altered rogenstein ooids and stromatolites exhibit trends similar to the composition of triassic seawater the presence of flat pebble conglomerates and sediment structures similar to herring bone cross stratification confirm the marine genesis i propose that cool seawater transgressed during a global rise of late permian early triassic base level from the barents shelf southward along reactivated extensional graben structures and flooded the central european permo triassic basin there the extremely hot and arid climate of the megacontinent pangaea caused increased evaporation of seawater and subsequent supersaturation with respect to calcium carbonate insignificant biomineralisation and high water energy in the shallow sea give rise to largely abiotic and biotically induced carbonate precipitation which resembles lake sediments at first sight benthic tropical carbonate production started with the next transgression during the rot formation leading to the sedimentation of marls and limestones during the spathian late olenekian

upper triassic carbonate deposits of seram indonesia palaeogeographic and geodynamic implications abstract the upper triassic limestones of central and western and seram were deposited on an extensive carbonate platform already identified in various localities all around the banda sea sinta ridge central east sulawesi buru misool and the wombat plateau off nw australia the triassic deposits are found in the parautochthonous as well as in the allochthonous series of seram the facies of the two series are of gondwanian australian type in the parautochthonous and of laurussian asian type in the allochthonous the asinepe limestone manusela formation on which this study is based has been considered as part of the allochthonous series the triassic reefal lithotypes can be divided into four main facies as follows 1 the boundstone facies forming the buildup cores 2 the oncolitic grainstone rudstone facies indicating high energy conditions 3 foraminiferal packstone grainstone facies characteristic of moderate to high energy conditions and 4 the foraminiferal megalodont mudstone facies inferred to have accumulated in a quiet lagoonal environment forming the buildup cores of about 4 m long 2 m high they are separated by depressions filled with reef detrital sands the asinepe limestone was deposited during the late triassic carnian norian to rhaetian this range is corroborated by foraminiferal and palynological data and the coral framebuilders give evidence for a norian rhaetian age there is a some consensus that seram and the island of buru located west of seram belong to the same tectonic block seram buru block according to geochemical and geodynamic interpretations the seram buru block is derived from irian jaya or from papua new guinea the palynological results are consistent with reconstructions that place the seram buru block in a palaeogeographic zone distinct from that of sulawesi and therefore from the kolonodale block for these reasons it is here proposed that during the upper triassic the seram buru block and the kolonodale block were two separated entities the former located in a more tropical position than the latter in addition the seram palynological association shows a composite microflora of the warm onslow and the cold ipswich types suggesting that the seram microcontinent moved progressively to the north and crossed the boundary between the temperate and the warm subequatorial belts at one point in the late triassic early jurassic

porosity permeability and textural heterogeneity of reservoir sandstones from the lower cretaceous putaohua member of yaojia formation weixing oilfield songliao basin northeast china abstract with the granulometric analyses mineral composition x ray diffraction xrd analyses porosity and permeability measurements scanning electron microscopy sem observations and mercury porosimetry measurements of the reservoir sandstones from four wells in the weixing oilfield songliao basin ne china the porosity permeability and pore structural heterogeneity features of the putaohua member sandstone of the lower cretaceous yaojia formation have been investigated in this paper the sandstones are mostly characterized by a similar deposition in continental detrital environments with quartz and feldspar taking the majority 97 and argillaceous minerals illite kaolinite and chlorite the minority 3 however their granule size sorting index porosity and permeability vary significantly in contrast to the generality that high porosity permeability often corresponds to large grain sizes and sorting indexes the porosity and permeability here show no good correlations to the grain size and sorting index suggesting the presence of a remarkable textural heterogeneity in terms of sequential change in permeability along the well depth cyclic sedimentation modes have been identified in some sub layers despite the porosity data showing little response to those scenarios this may be ascribed to the sandstone s peculiar intergranular pore structures in which the cementation occurred in pore lining and filling manners to different extents depending on their depositional environments the distributary channel facies tends to have lowest detrital clay content and rather open packed texture in pore lining cementation manner whereas sand sheet facies has pore filling manner the hg porosimetry analytical data are in fairly good agreement with the heterogeneous pore structures observed by sem large sized pores and channels connecting them though only accounting for a low percentage of the total porosity are believed to contribute mostly to the effective permeability in the sandstone reservoir such textural heterogeneities should be closely associated with the dynamic changing sedimentary facies of sandstones in the continental environment

paleoreef maps evaluation of a comprehensive database on phanerozoic reefs to get a better understanding of controls on reef development through time we created a comprehensive database on phanerozoic reefs the database currently comprises 2470 reefs and contains information about geographic position paleoposition age reef type dimensions environmental setting paleontological and petrographical features and reservoir quality of each buildup reef data were analyzed in two qualitatively different ways the first type of analysis was by visualization of paleogeographic reef distribution maps five examples late devonian early permian late triassic late jurassic middle miocene are presented to show the potential of paleoreef maps for paleogeographic and paleoclimatological reconstructions the second type of analysis was a numerical processing of coded reef characteristics to realize major trends in reef evolution and properties of reef carbonates the analysis of paleolatitudinal reef distributions through time shows pronounced asymmetries in some time slices probably related to climatic asymmetries rather than controlled by plate tectonic evolution alone the dominance of particular reef builders through time suggests that there are seven cycles of phanerozoic reef development first curves for the phanerozoic distribution of bioerosion in reefs bathymetric setting and debris potential of reefs are presented the observed pattern in the temporal and spatial distribution of reefs with reservoir quality may assist in hydrocarbon exploration statistical tests on the dependencies of reefal reservoir quality suggest that large size high debris potential low paleolatitude high amount of marine aragonite cement and a platform shelf edge setting favor reservoir quality reefal reservoirs are significantly enhanced in times of high evaporite sedimentation elevated burial of organic carbon low oceanic crust production low atmospheric co2 content and cool paleoclimate as well as when they are present in aragonite oceans

late early triassic microbial reefs of the western united states a description and model for their deposition in the aftermath of the end permian mass extinction abstract research in the western united states to reinvestigate and characterize the previously reported stromatolites of the latest early triassic spathian virgin limestone member of the moenkopi formation has shown that these microbial build ups formed patch reef mounds detailed field analysis of these reef mounds and the surrounding beds has established that they attained 1 2 m of topographic relief above the seafloor a petrographic study of these microbial mounds illustrates that they consisted of microbial fabrics as well as voids with early marine cements and formed in the absence of in situ metazoans these reef mounds formed during the aftermath of the end permian mass extinction that spanned the early triassic due to the devastation of marine metazoans at this extinction the early triassic has often been deemed a reef gap because no metazoan reefs are found at this time whereas colonial metazoan reefs are globally absent from lower triassic strata microbial build ups similar to these described from the western united states have been found in south china armenia southern turkey and greenland a regional early permian to late early triassic unconformity exists in the study region however analysis of these microbial reefs within a global context suggests that conditions favouring microbial reef development must have existed as long as 4 8 m y after the end permian mass extinction a depositional model of these microbial mounds indicates that flooding of the shelf with anoxic and or co2 rich deep waters may have fostered their occurrence

stromatolitic biotic systems in the mid triassic of israel a product of stress on an epicontinental margin abstract phanerozoic microbialites are carbonate precipitating biotic forms that are often described in modern systems from inter or supratidal hypersaline or fresh water environments and from beds associated with a variety of ecologically stressed environments over geologic time middle to late triassic microbialitic successions from southern israel were commonly subtidal and thrived under cryptic ecological stress conditions related to the regional configuration of the levant margin at that time the ladinian and carnian sequence at the ramon outcrop contains 18 successions with 28 microbialitic horizons these microbialites form isolated patches small bioherms and biostromes interleaved with other calcareous sediments including poorly diverse molluscan accumulations three distinct microbialitic facies and two associated molluscan facies were identified most were distinctly subtidal the two associated molluscan biofacies include a subtidal bivalve boundstone forming mounds and a bedded packstone of minute gastropods the ladinian carnian microbialites were not climatically forced environmental stress was caused by partial restriction of marine circulation due to tectonic movements and biotic accumulation on the outer edge of the levant margin comparison of coeval successions from central and northern israel and the north calcareous alps and southern alps in europe indicates a tethyan or global carbonate system of microbial producers separated from the open marine environment by shelf edge barriers therefore we conclude that the ramon microbialites represent a response to ecological stress of the carbonate system within the subtidal environment rather than solely to normal stresses of the intertidal environment

microbialites in a modern lagoonal environment nature and distribution tikehau atoll french polynesia abstract microbialites including stromatolitic structures gelatinous masses and mats develop in tikehau lagoon tuamotu french polynesia on the flanks and slopes of numerous pinnacles and motu islets between 0 and 25 m deep on coral colonies algal tufts or on lagoonal sediments individual stromatolitic structures consist of hemispherical domes and are produced by monospecific populations of filamentous cyanobacteria belonging to three distinctive phormidium species symploca and possibly to one new species of schizothrix gelatinous masses hanging from the ceiling of caverns are produced by phormidium laysanense microbial mats are well developed at all depths on pinnacle slopes and are produced by either monospecific or mixed cyanobacterial populations the study of micro and ultrastructure of stromatolites reveals that they result both from trapping and binding of sediments and from carbonate precipitation in addition to phototrophic biomineralization pervasive carbonate precipitation occurred in association with decaying organic matter the basic constructional elements of the precipitated carbonate consist of 0 1 0 2 m rounded bodies that form very fine anhedral to subhedral micrite their surfaces comprise extremely small carbonate granules 20 50 nm gradual changes ageing in the ultrastructure of carbonate precipitates include the precipitation of successive euhedral calcite layers around these grains widespread development of microbialites in this pristine lagoonal environment results from rapid blooms of microbial benthic communities possibly induced by temporary and local nutrient pulses nutrients seem to undergo a restricted circulation between the sediment and pinnacle reef frameworks pinnacles and reef islets are repeatedly affected by catastrophic storm events which cause redistribution of sediments and nutrients

upper triassic platform margin biofacies and the paleogeography of southern apennines abstract the upper triassic dolomitic successions of the monti della maddalena area southern apennines consist of white heavily recrystallized and cataclastic dolomites generally unsuitable for detailed facies analysis nevertheless evidences of bioconstructions can be found in several localities these evidences are represented by rudstones and possibly boundstones whose main components are fragments of sponges sphinctozoans inozoans chaetetids and corals generally encrusted by foraminifera red algae and problematica this association is much more diversified with respect to that of the microbial serpulid buildups which characterize the platform margin facies of most upper triassic successions of the southern apennines the monti della maddalena biofacies can be more readily compared with the bioconstructed facies of sicily and in general with the dachstein type reef of the tethyan realm the studied successions are interpreted according to the model of cirilli et al 1999 as formed at the margin of a carbonate platform facing a deep basin having good connection with the open sea while the microbial serpulid buildups formed on the margin of intraplatform restricted troughs with poorly oxygenated bottom waters our study discusses the relative paleogeographic position of the apennine platforms and the lagonegro basin the overall picture of the bioconstructed triassic facies distribution in southern apennines together with biofacies data from resedimented facies of lucania are compatible with paleogeographic reconstructions interpreting the monti della maddalena successions as representing the more external sector of the apennine platforms system flanking the lagonegro basin the latter bordered on its external side by apulia was part of a deep mesozoic domain comprising the imerese sicani basin of sicily and connected westward with the east mediterranean branch of western tethys our data exclude the possibility that the lagonegro basin was located in an internal position with respect to all the apenninic and apulian platforms system

dolomite mountains and the origin of the dolomite rock of which they mainly consist historical developments and new perspectives beginning in the late 18th century the dolomite mountains in northern italy have been the location for major sedimentological developments from the discovery of the mineral dolomite to the formulation of the coral reef hypothesis to explain the origin of the massive dolomite structures that define the splendid scenery of the region further the dolomite mountains have inspired voluminous research into the origin of dolomite questioning whether dolomite is a primary precipitate or a secondary replacement product recently with the recognition that microbes can mediate dolomite precipitation a new geomicrobiological approach combining the study of modern natural environments with bacterial culture experiments is now being used to calibrate or interpret microbial evidence derived from the dolomite rock record this three pronged methodology applied to the study of dolomite formation holds great promise for future research into the dolomite problem and provides a new impetus to revisit the dolomite mountains in the 21st century

microbial foraminiferal episodes in the early aptian of the southern tethyan margin ecological significance and possible relation to oceanic anoxic event 1a two regionally significant microbial foraminiferal episodes 150 kyr each occur within the early aptian shallow marine platform in oman and throughout eastern arabia the stratigraphically lower of these two intervals is characterized by isolated or coalescent domes that share similarities with modern open marine stromatolites from the exuma cays bahamas the upper interval is predominantly built by a problematic lithocodium bacinella consortium in buildup and massive boundstone facies based on highresolution chemostratigraphy these shoalwater intervals are coeval with oceanic anoxic event 1a oae1a livello selli field evidence demonstrates that the buildup episodes alternate with stratigraphic intervals dominated by rudist bivalves this biotic pattern is also recognized in other coeval tethyan sections and is perhaps a characteristic shoalwater expression of the oae1a the short lived regional expansions of this microbial foraminiferal out ofbalance facies cannot be explained by local environmental factors salinity and oxygen level alone and the buildup consortia do not occupy stressed refugia in the absence of grazing metazoans judging from recent analogues the main fossil groups i e microbial assemblages macroalgae larger sessile foraminifera and rudist bivalves all favoured elevated trophic levels but with different tolerance limits the implication of this is that the influence of palaeofertility events possibly related to oae1a on carbonate platform community structures must be investigated the observations made in these coastal sections are a significant first step for the improved understanding of the early aptian period of biotic oceanic and climatic change

microbial carbonate abundance compared with fluctuations in metazoan diversity over geological time abstract secular variation in microbial carbonate abundance may be reflected by stromatolite morphotype diversity and reefal microbial carbonate abundance these datasets reveal long term changes over the past 3000 myr that include a peak of abundance 1250 myr ago late proterozoic decline cambrian resurgence and fluctuating decline during the remainder of the phanerozoic it is conceivable that proterozoic metazoan diversification coincided with inception of stromatolite decline 1250 myr ago but microbial carbonate increase during cambrian metazoan radiation together with failure of microbial carbonates to increase in the aftermaths of the end ordovician end triassic and end cretaceous mass extinctions suggest that factors in addition to metazoan competition significantly influenced long term changes in microbial carbonate abundance

the changing climate framework and depositional dynamics of triassic carbonate platforms from the dolomites abstract the triassic of the dolomites offers a valuable opportunity to investigate the relationships between climate fluctuations and the changing depositional dynamics of carbonate platforms the reconstruction of the large palaeoclimatic modification is based on the synthesis of multiple sedimentological palaeobotanical pedological and geochemical proxies the triassic climate fluctuations were generally fast in nature and were probably associated with a latitudinal shift of the monsoon belts during the triassic the dolomites were placed at an intertropical northern latitude of about 16 18 and were generally dominated by dry climate and elevated temperature at least five pulses toward moister climate are however documented dated to early olenekian middle anisian late ladinian middle carnian and late norian times within this variable climatic scenario the carbonate systems record a global evolutionary trend from late permian early triassic regional shelves rich in loose micrites and bio calcarenites to anisian ladinian synsedimentary cemented steep sided 35 40 high relief platforms and back to carnian low angle ramps moist transgressive episodes were surprisingly prone to the spreading of corals and other colonial reef organisms probably because of the reduced space competition by syndepositional cementation structures the permo triassic boundary extinction dramatically impacted on the calcified organism communities but the carbonate depositional architecture nevertheless stayed almost unaffected through the boundary the early triassic and earliest anisian were commonly associated with hyperhaline sometimes evaporitic conditions intervals of moister climate and efficient river discharge are however documented by earliest induan and early olenekian sediments the latter terrigenous deposits matched a crisis in the carbonate production after a return to arid conditions during the anisian a fluctuation toward moister climate developed associated to a massive continental vegetation cover the anisian tectonic activation of the region fragmented the previous carbonate shelf triggering the development of three generations of fast prograding but globally backstepping isolated platforms recording an increasing role of the synsedimentary cementation a dry climate dominated the late anisian and early ladinian interval at the time a fast subsidence pulse was associated with platform drowning and basinal anoxia only a few aggrading pinnacles were able to survive providing the nuclei for larger prograding platforms during a dry climate interval massive syndepositional cementation generated a major source of carbonate carbonate production stayed active through the ladinian magmatic phase but the onset of volcanism was associated with a large modification in the platform carbonate facies which became dominated by automicrites moist climate phases are well documented again during the late ladinian followed by a return to dry conditions the late ladinian early carnian platforms prograded toward the eastern dolomites depocentre eventually infilling almost the whole of the accommodation space the middle portion of the carnian recorded renewed sharply moist phases associated with the demise of the rimmed platforms and with the return to loose sediment ramps at least four separated humid fluctuations can be identified in this carnian interval alone climate then returned to persistent aridity until the late norian moist phase

gastropod evidence against the early triassic lilliput effect reply size reduction in the aftermath of the permian triassic mass extinction event has repeatedly been described for various marine organisms including gastropods the lilliput effect a smithian gastropod assemblage from utah usa reveals numerous large sized specimens of different genera as high as 70 mm the largest ever reported from the early triassic other gastropods reported from serbia and italy are also as large as 35 mm size frequency distributions of the studied assemblages indicate that they were not unusually small when compared with later mesozoic and modern faunas the occurrence of large sized gastropods less than 2 ma after the permian triassic mass extinction refutes the lilliput hypothesis in this clade at least for the last 75 of the early triassic

early triassic calcimicrobial mounds and biostromes of the nanpanjiang basin south china stanley s model 1988 proposed that a permiantype reef fauna survived the early triassic reefless period in yet undiscovered refuges in the ancestral pacific ocean and then reappeared as the builders of middle triassic reefs flugel 1994 in contrast suggested that the middle triassic reefbuilding fauna are not holdovers from the permian but bear only a superficial resemblance to permian fossils recent publications reflect a consensus that the early triassic lacked reefs and reef mounds although some authors acknowledged the possibility that reef like structures may have existed in poorly explored areas such as south china and russia senowbari daryan et al 1993 flugel 1994 it is shown herein that calcimicrobial framework mounds and biostromes existed in the early triassic in the nanpanjiang basin of south china organic framework in this paper refers to a three dimensional biologically constructed network of calcified fossils that forms a rigid mass and supports an interconnected network of internal cavities that were open during accumulation although the calcimicrobial frameworks discussed herein are much smaller than frameworks of modern metazoan reefs the term framestone is more appropriate for these fabrics than other reef rock terms such as bindstone or bafflestone embry and klovan 1971 these calcimicrobial mounds and biostromes are important as the first organic framestones documented from the early triassic

paleoclimatic significance of phanerozoic reefs a database of pre quaternary phanerozoic reefs is used to test the significance of ancient reefs as paleoclimatic tracers the compilation of reef paleolatitudes through time and comparison with published paleoclimate curves shows that neither the width of the tropical reef zone nor the total latitudinal range of reefs is correlated with published estimates of paleotemperature however reefs trace paleoclimate indirectly algal reefs tend to prevail during icehouse climatic intervals and distinct high latitude reefs are only developed in cold intervals whereas during greenhouse episodes the reef zone usually ended abruptly at a particular latitudinal boundary in the subtropics additionally different biotic reef types tended to be concentrated in different latitudes the lowest latitudes have usually been occupied by coralline sponge or microbial reefs coral reefs tended to grow in intermediate latitudes and bryozoan reefs constantly occupied the highest latitudinal position

reservoir and aquifer characterization of fluvial architectural elements stubensandstein upper triassic southwest germany this paper aims at a quantitative sedimentological and petrophysical characterization of a terminal alluvial plain system exemplified by the stubensandstein south german keuper basin the study follows the outcrop analogue approach where information derived from outcrops is collected in order to enhance interpretation of comparable subsurface successions quantitative data on sandbody geometries porosities and permeabilities are presented in order to constrain modelling of subsurface sandbodies and permeability barriers for sedimentological characterization the method of architectural element analysis miall a d 1996 the geology of fluvial deposits springer berlin was used and modified to include poroperm facies a special photo technique with a precise theodolite survey was developed to create optically corrected photomosaics for outcrop wall maps from up to 20 000 m2 large outcrops nine architectural elements have been classified and quantified bedload mixed load and suspended load channel fills are separated the petrophysical characterization of the architectural elements integrated porosity and permeability measurements of core plugs with gamma ray measurements along representative sections it could be demonstrated that certain architectural elements show a characteristic poroperm facies four scales of sedimentary cycles have been recognized in the stubensandstein cyclic sedimentation causes changing lithofacies patterns within the architectural elements depending on their position in the sedimentary cycle stratigraphic position exerts only some paleogeographic position exerts significant influence on porosity and permeability of the sandbodies the highest poroperm values were found in proximal areas of the alluvial plain and in middle parts within sedimentary macrocycles the strong internal heterogeneity on the alluvial plain system is important for its reservoir and aquifer characteristics compartments of bedload channel sandstones in medial positions of a stratigraphic cycle represent very good reservoirs or aquifers the seals or aquicludes are formed by extensive floodplain claystones lacustrine sediments paleosols and suspended load deposits strongly cemented zones of sandstones represent aquitards

the epicontinental subsiding margin of the triassic in northern israel north arabian plate abstract the triassic sedimentary pattern of the north arabian margin represents a transition from continental to deep marine we here present a transect part of this suite from southern to northern israel cuttings from the ramalla s and devora n boreholes were studied by petrographic and cathodoluminescence microscopy biotic and sedimentological components were grouped into microfacies upon which a carbonate evaporitic depositional facies model was based mid to inner ramp conditions persisted along the transect essentially following a s n depositional strike with outer ramp to basinal facies to the west five low order lo cycles were identified and integrated into a sequence stratigraphic model with eustatic tectonic and differential subsidence components lo cycle 1 is late anisian pelsonian cycle 2 is late anisian to longobardian cycle 3 is early carnian cycle 4 is late carnian and cycle 5 is at the carnian norian transition facies range from supratidal via lagoonal facies in late hst or lst to calcarenitic shoals and short term deepening to offshore at maximum flooding cycles 1 and 2 are non evaporitic with a clastic influx event in cycle 2 cycles 3 and 4 contain sabkha or salina evaporites in the lagoonal facies that end in the lower part of cycle 5 these facies group into a higher order cyclicity with discrete events that can be correlated between the boreholes depositional and burial history were correlated to alpine and arabian plate stratigraphy over 20 myr from the anisian pelsonian to the norian siliciclastic carbonate and evaporite dominated environments indicate climates ranging from relatively humid to extremely arid rapid subsidence in the late anisian is attributed to neotethyan rifting of northeastern gondwana from latest anisian to early carnian reduced subsidence took place in the face of eustatic sea level rise renewed subsidence in the carnian is attributed to further neotethyan rifting subsidence terminated in the norian with uplift to the north attributed to pre volcanic doming

relating small scale sedimentary structures and permeability in a cross bedded aquifer summary the objective of this study is to investigate the relation between small scale sedimentary structures and permeability in the brussels sands formation an early middle eocene shallow marine sand deposit in central belgium that constitutes a major groundwater source in the region a field campaign was carried out consisting of field observations of the sedimentary structures and in situ measurements of air permeability the sedimentary structures were interpreted sketched digitally photographed and measured in a representative outcrop additionally a total of 2750 cm scale air permeability measurements were carried out in situ analysis of the spatial distribution of sedimentary structures and permeability shows that clay rich sedimentary features such as bottomsets and distinct mud drapes exhibit a different statistical and geostatistical permeability distribution compared to the other lithofacies in the cross bedded sands spatial analysis of the air permeability data shows that permeability anisotropy in the cross bedded lithofacies is dominated by the foreset lamination orientation these results show that small scale sedimentary heterogeneity strongly influences the local spatial distribution of the hydraulic properties and results in permeability heterogeneity and stratification that would produce anisotropy in upscaled permeability values

tubiphytes archaeolithoporella girvanella reefal facies in permian buildup mino terrane central japan abstract the lower to middle permian okumino buildup of the mino terrane central japan formed a carbonate cap on a seamount which was sitting in an open ocean realm microscopic examination reveals considerable amounts of tubiphytes archaeolithoporella and girvanella in these rocks these low laminar encrusting organisms together with cystopore bryozoa and syndepositional radial fibrous cements formed bindstones the bindstones are interpreted as having formed wave resistant algal reefal mounds on the marginal terrace of the okumino buildup which also has the lagoonal flat sand bar or shoal and foreslope facies the okumino buildup is closer in its biotic association of major encrusting organisms to the trogkofel buildup in southern alps than to the capitan reef complex in new mexico and texas the similarity implies that tubiphytes and archaeolithoporella were the most predominant and significant rock forming encrusting organisms in early to early middle permian times

deev jahi model of the permian triassic boundary mass extinction a case for gas hydrates as the main cause of biological crisis on earth the smoking gun revealing the secrets of the end permian mass mortality is a unique 1 2 m thick layer consisting of 5 20 cm long crystals of calcite that occurs precisely at the permian triassic boundary ptb in iran armenia turkey and china this layer is interpreted as synsedimentary abiotic seafloor cement indicative of precipitation from a highly carbonate supersaturated seawater its 13 c composition 13 c 0 pdb is 4 to 5 pdb lower than the typical upper permian values 4 to 5 pdb suggesting the involvement of massive amounts of gas hydrate ch 4 13 c 60 pdb the temporal coincidence of the cement layer with the ptb suggests that the process that promoted seafloor cementation was also responsible for the biological crisis a cementation model is developed based on accumulation dissociation cycle of gas hydrates which also explains the mass extinction at the ptb the upper permian accumulation period of gas hydrates ended abruptly adjacent to the ptb and the dissociation event began releasing 3 2 to 4 7 10 18 g ch 4 into the ocean oxidation of ch 4 in the water column created a seawater that was charged with co 2 an oceanic acid bath and had lower than normal o 2 content but not anoxic this oceanic acid bath first dissolved suspended fine grained carbonate particles and small calcareous organisms followed by extensive dissolution of platform carbonates raising ca 2 and hco 3 concentrations of seawater when the release of ch 4 declined the acid bath ocean became a soda ocean precipitating massive amount of seafloor cements observed globally at the ptb the study suggests that prior to cement precipitation the ptb ocean was charged with co 2 warm had low oxygen high ca 2 and high hco 3 concentrations these conditions collectively created stressful conditions causing the marine mass mortality the leakage of ch 4 to the atmosphere produced a super hot climate resulting in the biological devastation on land the proposed kill mechanism is developed on the basis of the physical clue the cement layer left behind by the killing process the change in ocean chemistry the accumulation dissociation cycles of gas hydrates also explain the 13 c pattern of marine carbonates and the periodicity of mass extinction events during the phanerozoic accumulation periods were long 5 to 20 my providing favorable conditions for ecosystem development pardeess phase the dissociation events were short and catastrophic 10 to 500 ky causing low oxygenation super hot climate and biological devastation doozakh phase it appears that most mass extinctions of the phanerozoic have been related to the internal working of the earth system during the phanerozoic methane has played the role of the deev jahi a female demon in persian mythology whose task is to attack the earth every so often to kill life on land and in sea

kalkowsky s stromatolites revisited lower triassic buntsandstein harz mountains germany abstract the term stromatolite was proposed by kalkowsky 1908 z dt geol ges 60 68 125 for structures he discovered in the carbonates of the lower triassic buntsandstein of the harz mountains in central germany we have re examined these localities to clarify kalkowsky s descriptions and to deduce the environmental conditions of stromatolitic growth the lower buntsandstein was deposited in a closed lacustrine basin the central european permo triassic basin the depositional environment was a playa lake with variable salinity in the centre of the basin oolite beds are intercalated in the mainly siliciclastic succession which is composed of 20 fining upward cycles thought to have been produced by climatic variations stromatolites occur almost exclusively on the surface of oolite beds stromatolitic structures consist of millimetre thick laminated crusts and centimetre high branching columnar forms smaller and bigger 2 m high domes are composed of secondary order columns and intercalated crusts occasionally upper surfaces of the domes are pitted due to syndepositional dissolution despite of the overall intense sparitization two groups of stromatolitic microstructures can be distinguished spongy fenestrate and fan like fabrics the spongy fenestrate fabric is similar to that one caused by the recent cyanobacteria phormidium calothrix and dichothrix and the fan like fabric to rivularia laminated crusts called stromatoid by kalkowsky are interpreted as being of cement origin and formed by quick precipitation the change from columnar to domical forms may reflect changes of hydrodynamic conditions clear photoautotrophism suggests that cyanobacteria or eukaryotes were the dominant organisms involved in the formation of kalkowsky s stromatolites influx of ooids or siliciclastic mud interrupted or terminated the stromatolitic growth the morphology growth pattern and fabrics of stromatolites were most likely controlled by ecological factors which all seem to be related to the general hydro climatic evolution of the lower buntsandstein

modelling potential hydrological impact of abandoned underground mines in the monday creek watershed ohio abandoned underground mines aum have caused dramatic environmental effects that are closely linked to regional sustainability this paper explores the potential hydrological impact of aum in the monday creek watershed a typically mined area in appalachian region using the soil and water assessment tool swat 2005 model and sequential uncertainty fitting sufi 2 calibrated at both the global and local scales the locally calibrated model better incorporates those key parameters relevant to aum for specific sub basins and hydrologic response units data from the years 2003 2004 were used for calibration and 2005 2006 for validation the results were quite satisfactory both the coefficient of determination r2 and the nash sutcliffe efficiency statistic were over 0 80 the potential influences of aum were assessed by modelling an alternative scenario assuming no aum for the period 2003 2009 results show that the hydrological process of lateral subsurface flow plays a dominant role in linking aum to overall watershed hydrology the potential hydrological impact of aum is an increased annual lateral flow of 82 1 and a decrease in annual surface flow by 15 leading to an increase of 16 9 in annual water yield for the monday creek watershed the seasonal fluctuation of water yield has a similar trend to lateral flow decreasing from march to august and increasing from august to january higher volume higher flow peaks and higher recession constants characterized the hydrograph of daily streamflow from aum the results indicate that more emphasis should be put on lateral flow for further study of acid mine drainage and flooding control in those watersheds with aum copyright 2012 john wiley sons ltd

hydrogeological and environmental impact of coal mining jharia coalfield india the jharia coalfield is the most important and active minig region it experiences groundwater inflow and affects groundwater levels in overlying aquifers and it provides the basis for a conceptual model of the hydrogeological impacts of coal mining the several sandstone aquifers of the overburden are separated by aquitards that limit vertical hydraulic connection but the inflow responds to seasonal events and seems to be linked to shallow groundwater behavior the mine drainage behavior suggests a hydraulic connection between the mine and the shallower groundwater system the greatest declines are directly above the panels with an immediate response to coal mining the inflow is localized by natural and induced fracture zones and is mostly into recent workings the groundwater behavior is controlled by hydraulic property changes caused by mine induced fracturing the hydrological and chemical qualities of the shallow groundwater regime in 13 mining collieries in mukunda block have been investigated water samples collected from 30 shallow monitoring dug wells were chosen for the study rainfall runoff and infiltration rates have been calculated in the area the water quality plottings were used to interpret the distribution of individual chemical parameters and in predicting the water quality the underground mine water has been classified as 1 unconfined groundwater in the calcareous siltstone and sandstone its composition is na ca so4 and na mghco3 with moderate total dissolved solids tds 200 1480 ppm 2 the deep groundwater originating from the coal seams and associated sediments in the near surface environments this is a na hco3 water with higher tds and 3 spoil dump waters are essentially na hco3 with high tds this article presents some hydrologic results and conclusions relating to the hydrogeological and environmental impacts of the coal mining in the jharia coalfield

permo triassic boundary superanoxia and stratified superocean records from lost deep sea pelagic cherts of japan and british columbia canada recorded a long term and worldwide deep sea anoxic oxygen depleted event across the permo triassic or paleozoic and mesozoic boundary 251 2 million years ago the symmetry in lithostratigraphy and redox condition of the boundary sections suggest that the superocean panthalassa became totally stratified for nearly 20 million years across the boundary the timing of onset climax and termination of the oceanic stratification correspond to global biotic events including the end guadalupian decline the end permian extinction and mid triassic recovery

geobiology of microbial carbonates metazoan and seawater saturation state influences on secular trends during the phanerozoic abstract microbial carbonates are long ranging essentially bacterial aquatic sediments their calcification is dependent on ambient water chemistry and their growth is influenced by competition with other organisms such as metazoans in this paper these relationships are examined by comparing the geological record of microbial carbonates with metazoan history and secular variations in caco3 saturation state of seawater marine abundance data show that microbial carbonates episodically declined during the phanerozoic eon past 545 myr from a peak 500 myr ago this abundance trend is generally inverse to that of marine metazoan taxonomic diversity supporting the view that metazoan competition has progressively limited the formation of microbial carbonates lack of empirical values concerning variables such as seawater ionic composition atmospheric partial pressure of co2 and ph currently restricts calculation of caco3 saturation state for the phanerozoic as a whole to the use of modeled values these data together with palaeotemperature data from oxygen isotope analyses allow calculation of seawater caco3 saturation trends microbial carbonate abundance shows broad positive correspondence with calculated seawater saturation state for caco3 minerals during the interval 150 545 myr ago consistent with the likelihood that seawater chemistry has influenced the calcification and therefore accretion and preservation of microbial carbonates these comparisons suggest that both metazoan influence and seawater saturation state have combined to determine the broad pattern of marine microbial carbonate abundance throughout much of the phanerozoic in contrast for the major part of the precambrian it would seem reasonable to expect that seawater saturation state together with microbial evolution was the principal factor determining microbial carbonate development interrelationships such as these with feedbacks influencing organisms sediments and the environment are central to geobiology

aftermath of the permian triassic mass extinction event paleoecology of lower triassic carbonates in the western usa paleoecologic study of invertebrate faunas from three successive early triassic seaways reveals that biotic recovery from the end permian mass extinction event was slow and that full recovery did not occur until after the early triassic simple cosmopolitan opportunistic generalists and low diversity low complexity paleocommunities were characteristic of the entire early triassic in the western usa an increase in guild and taxonomic diversity was observed with the addition of several new higher taxa in the late early triassic spathian to the almost exclusively molluscan faunas of the earlier early triassic nammalian potential disaster forms the inarticulate brachiopod lingula and the paper pecten claraia dominated the earliest early triassic faunas griesbachian and even occurred in the late early triassic normal marine stromatolites comparison with data on faunas from the permian and triassic suggests that even the most diverse early triassic faunas in the spathian were rather low in guild diversity and species richness these characteristics of genera and paleocommunities in the early triassic may be typical of mass extinction aftermaths

relating lithofacies to hydrofacies outcrop based hydrogeological characterisation of quaternary gravel deposits abstract a considerable part of today s drinking water supplies in europe and north america rely on clean groundwater from gravelly valley aquifers of quaternary age the sedimentary architecture the distribution of lithofacies and of architectural elements in such heterogeneous deposits are of fundamental importance for the analysis of groundwater flow and contaminant transport as the aquifers are not directly accessible for observation representative outcrop analogues were used to study the sedimentology on a local scale conventional sedimentological classification schemes were adapted for the purpose of hydrogeological evaluations measurements of hydraulic properties were then used to define a set of 5 hydrofacies from 23 possible sediment lithofacies a digital photographic mapping procedure was developed to allow fast data acquisition in the field the sedimentologically interpreted outcrops were stored in a gis style database and thus allow the output for further sedimentological or hydrogeological analysis

lower triassic large sea floor carbonate cements their origin and a mechanism for the prolonged biotic recovery from the end permian mass extinction precipitation of inorganic calcium carbonate is a common occurrence in both modern and ancient marine environments however synsedimentary growth of large 5 10 cm crystalline carbonate cements directly onto the sea floor has been thought to be limited to the proterozoic when seawaters were highly oversaturated with calcium carbonate compared to average phanerozoic values outer shelf to slope deposits of the lower triassic union wash formation in east central california deposited in oxygen restricted settings contain crystalline calcium carbonate cements that appear to have grown directly on the sea floor paleoenvironmental analyses indicate that these large calcium carbonate cements grew under conditions that were similar to those proposed for the precipitation of inorganic calcite in the black sea sulfate reduction of organic matter led to an increase in the amount of bicarbonate ion in deep waters and a concomitant increase in co 2 and alkalinity mixing with surface waters led to co 2 degassing and precipitation of cements from waters supersaturated with calcium carbonate the presence of these cements and associated facies thus provides evidence of harsh environmental conditions in the early triassic at the regional level which may have acted in concert with biotic effects of the end permian mass extinction as well as similar deleterious conditions e g shelf anoxia in other regions to produce a prolonged as well as temporally and geographically variable biotic recovery from this mass extinction