geometry and distribution of regional joint sets in a non homogeneous stress field case study in the ebro basin spain abstract three regional joint sets striking n s e w and wnw ese affect the tertiary rocks of the central ebro basin from analysis of their chronological relationships and spatial distribution it is concluded that they correspond to two different tectonic events the n s set oldest and the e w set younger are present in the southern and central sectors while the wnw ese joint set predominates in the northern one the n s joints propagated in response to joint normal and fluid loads under an intraplate stress field with shmax oriented near n s related to forces caused by the convergence of africa iberia and europe and rifting at the valencia trough during the sedimentary infilling of the basin these joints are only present in the southern part of the area the e w joint set in the southern central sector records the same fracturing event as the wnw ese set does in the northern one its orientation was modified by the presence of the older n s set in the south which perturbed the regional stress field the younger wnw ese and e w joint sets are interpreted as unloading joints these propagated as a consequence of flexural uplift and exhumation related to isostatic rebound at the pyrenees and the ebro foreland basin a numerical approach is used to explain the inhomogeneous distribution of the n s joint set in terms of their absence being controlled by the depth of the water table at the time of their formation

a review on natural and human induced geohazards and impacts in karst karst environments are characterized by distinctive landforms related to dissolution and a dominant subsurface drainage the direct connection between the surface and the underlying high permeability aquifers makes karst aquifers extremely vulnerable to pollution a high percentage of the world population depends on these water resources moreover karst terrains frequently underlain by cavernous carbonate and or evaporite rocks may be affected by severe ground instability problems impacts and hazards associated with karst are rapidly increasing as development expands upon these areas without proper planning taking into account the peculiarities of these environments this has led to an escalation of karst related environmental and engineering problems such as sinkholes floods involving highly transmissive aquifers and landslides developed on rocks weakened by karstification the environmental fragility of karst settings together with their endemic hazardous processes have received an increasing attention from the scientific community in the last decades concurrently the interest of planners and decision makers on a safe and sustainable management of karst lands is also growing this work reviews the main natural and human induced hazards characteristic of karst environments with specific focus on sinkholes floods and slope movements and summarizes the main outcomes reached by karst scientists regarding the assessment of environmental impacts and their mitigation

a generalized genetic framework for the development of sinkholes and karst in florida u s a karst topography in florida is developed on the tertiary limestones of the floridan aquifer post depositional diagenesis and solution have made these limestones highly permeable t ca 50 000 m2 d zones of megaporosity have formed at unconformities and dissolution has enlarged joints and fractures erosion of the overlying clastic miocene hawthorn group strata on one flank of a structural arch has exposed the limestone the elevated edge of the hawthorn cover forms the cody scarp ubiquitous solution pipes have previously formed at joint intersections and are now filled downwashing of the fill deeper into solution cavities in the limestone and subsidence of the overlying unconsolidated sediments causes surface collapse a subsidence doline or sinkhole this process may penetrate up to 60 m of the semi consolidated hawthorn cover as occurred when the winter park sinkhole developed dense clusters of solution pipes may have formed cenotes which are now found on the exposed limestone terrain

karst breakdown mechanisms from observations in the gypsum caves of the western ukraine implications for subsidence hazard assessment the term karst breakdown is employed in this paper to denote the totality of processes and phenomena of gravitational and or hydrodynamic destruction of the ceiling of a karst cavity and of the overlying sediments it refers not only to the existence of a surface subsidence collapse feature but first of all to the internal hidden in the subsurface structures that precede development of a surface form this study reports and discusses the results of direct mapping and examination of breakdown structures in the gypsum karst of the western ukraine at the level of their origin i e in caves the accessibility of numerous laterally extensive maze cave systems in the region provided an excellent opportunity for such an approach which made it possible to examine the relationship between breakdown structures and particular morphogenetic or geological features in caves and to reveal stages of breakdown development it is found that breakdown is initiated mainly at specific speleogenetically or geologically weakened localities which classify into a few distinct types the majority of breakdowns which are potent to propagate through the overburden relate with the outlet cupolas domepits that represent places where water had discharged out of a cave to the upper aquifer during the period of transverse artesian speleogenesis distribution of breakdown structures does not correlate particularly well with the size of the master passages several distinct mechanisms of breakdown development are revealed and most of them proceed in several stages they are guided by speleogenetic geological and hydrogeological factors the study confirms that a speleogenetic approach is indispensable to the understanding of breakdown pre requisites and mechanisms as well as for eventual subsidence hazard assessment direct observations in caves aimed both at speleogenetic investigation and breakdown characterization on regional or site specific levels should be employed wherever possible

sinkholes in hypogene versus epigene karst systems illustrated with the hypogene gypsum karst of the sant miquel de campmajor valley ne spain abstract the garrotxa banyoles artesian aquifer system in ne spain includes zones with epigene and hypogene evaporite karst and sinkhole development the sinkhole fields related to hypogene evaporite dissolution are associated with the discharge zones of the aquifer where groundwater from a confined limestone rises traversing an overlying gypsum formation capped by thick marls this work analyses the sinkhole field developed in the sant miquel de campmajor valley smcv a discharge area of the aquifer where a cartographic inventory including 94 sinkholes has been produced sinkholes in this hypogene gypsum karst are mainly large caprock collapse sinkholes rooted in deep seated cavities generated by interstratal hypogene karstification as corroborated by an electrical resistivity imaging eri survey they show a non clustered distribution within the sinkhole field and the variations in size and density across the area are mainly controlled by the thickness of the marl caprock the magnitude and frequency relationships of the sinkholes can be modelled with a high goodness of fit with a log normal function like in other regions of the world however in this deep seated hypogene system the depressions show much larger dimensions potential differences between the sinkholes developed in hypogene and epigene karst environments are discussed including their distribution with respect to the groundwater flow system their spatial patterns and dimensions

quantitative assessment of volcanic ash hazards for health and infrastructure at mt etna italy by numerical simulation abstract we performed a quantitative hazard assessment to determine the potential impacts of volcanic tephra fall on human health and infrastructure in the vicinity of mt etna italy using the numerical model vol calpuff we explored the dynamics of long lasting weak plume eruptions and their effects on the surrounding region input data are based on credible estimates of the main parameters characterising the expected events as derived from the historically observed and reconstructed explosive record of mt etna monte carlo techniques are used to capture the effects on estimates of finer ash concentration and total ground deposition due to volcanological uncertainties and meteorological variability numerical simulations compute the likelihoods of experiencing critical 10 m volcanic particle vp 10 concentrations in ambient air and tephra ground deposition at various populated locations around the volcano including the city of catania and at key infrastructure such as airports and main roads results show how the towns and infrastructure on the east side of the volcano are significantly more exposed to ash related hazards than those on the west side in accordance with wind statistics simulation outcomes also illustrate how at the sites analysed the amount of deposited particulate matter is proportional to the intensity i e mass flow rate of the event whereas predicted values of vp 10 concentrations are significantly larger for smaller events due to the reduced dispersal of low altitude plumes the use of a simple re mobilization model highlights the fact that particle re suspension needs to be considered in the estimation of vp 10 values our findings can be used to inform civil protection agencies responsible for mitigating tephra fall impacts to human health road transport and aviation safety

characterization of compounds in unresolved complex mixtures ucm of a mesoproterzoic shale by using gc gc tofms abstract unresolved complex mixtures ucm in shales have important implications for organic matter formation and diagenesis however their origin is not well understood one important reason for this is lacking the knowledge of their molecular compositions here using the comprehensive two dimensional gas chromatography gc gc coupled with time of flight mass spectrometry tofms we conduct a pilot study based on a mesoproterozoic black shale from north china detailed identification of compounds was made and a possible new origin was suggested results show that the separation of ucm hydrocarbons by a reversed phase column system polar non polar is efficient for the identification of molecular composition of ucm the ucm in the shale is composed mainly of c 11 c 27 compounds including paraffin hydrocarbons cycloalkanes and aromatics in particular 1 3 cyclic paraffins with a short chain alkyl group multi branched isoparaffins and their homologous series which are indicative of isomerization of molecules intensively this implies that the origin of the ucm might include the isomerization of organic molecules in addition to the commonly thought microbial activities this study improves the understanding of the geochemical compositions and origin of ucm in shales

a three dimensional eulerian model for transport and deposition of volcanic ashes abstract volcanic ash fallout represents a serious threat to people living near active volcanoes because it can produce several undesirable effects such as collapse of roofs by ash loading respiratory sickness air traffic disruption or damage to agriculture the assessment of such volcanic risk is therefore an issue of vital importance for public safety and its mitigation often requires to evaluate the temporal evolution of the phenomenon through reliable computational models we develop an eulerian model named fall3d for the transport and deposition of volcanic ashes the model is based on the advection diffusion sedimentation equation with a turbulent diffusion given by the gradient transport theory a wind field obtained from a meteorological limited area model lam and the source term derived from by buoyant plume theory it can be used to forecast either ash concentration in the atmosphere or ash loading on the ground model inputs are topography meteorological data given by a lam mass eruption rate and a particle settling velocity distribution a test application to the july 2001 etna eruption is presented

the vol calpuff model for atmospheric ash dispersal 2 application to the weak mount etna plume of july 2001 1 here the application of the vol calpuff model by barsotti et al to a weak plume erupted from mount etna in july 2001 is presented and discussed the reconstruction of the explosive event was obtained by using high resolution weather forecasts produced by a mesoscale nonhydrostatic model and volcanic source data coming from observations and analytical studies the plume rise and atmospheric dispersal models were investigated over 5 d of eruption mostly in terms of column height aerial ash concentration and ground deposition modeling results are shown as a function of various source conditions and compared to independent observations derived from satellite images and deposit mapping the application of vol calpuff clearly highlights the crucial role played by meteorological conditions in determining dispersal dynamics some of the most important effects described by the model are 1 the large wind field influence on the plume height determination and tilting 2 the contrasting dispersal patterns of ash particles of different sizes 3 the complex and somehow nonintuitive distribution of ash on the ground resulting in preferential directions of dispersal and quite irregular deposit patterns and 4 the impossibility to reproduce both the column height and the deposit accumulation pattern by adopting a steady state vent mass flow rate over the investigated 4 d period due to observed temporal changes in eruption dynamics modeling results also suggest the need for further integration of simulation outcomes with remote sensing and field reconstructions on ash dispersal processes in future

degradation and maturity controls on oil field petroleum column heterogeneity in the gullfaks field norwegian north sea abstract a geochemical mapping of the gullfaks reservoir petroleum column based on 226 reservoir core extracts and 23 drill stem test dst and repeat formation test rft oil samples indicates the presence of statistically testable lateral compositional heterogeneities in the petroleum column these different petroleum populations can be related to lateral filling of the field from two source basins and a more pervasive subsequent episode in reservoir biodegradation petroleum maturity gradients within the field were detected using conventional biomarker gc ms methods on saturated hydrocarbon fractions the degree of biodegradation was monitored by quantitative gc of n alkanes in whole oil samples using a squalane internal standard the observed compositional differences in the gullfaks petroleum column are consistent with diffusion being the primary mixing process thermal convection being eliminated on both compositional and modeling grounds compositional differences between core extracts and dst samples from the same intervals suggest that fractionation of petroleum might occur during testing and that interpretation of reservoir petroleum columns from mixed sample sets should be treated cautiously

organic geochemistry and depositional environment of the aptian bituminous limestone in the kale gumushane area ne turkey an example of lacustrine deposits on the platform carbonate sequence the jurassic lower cretaceous aged carbonate sequence is widely exposed in the southern zone of eastern pontides aptian black bituminous limestone is found in the upper part of this sequence in the kale area gumushane this limestone contains faunal remains e g gastropod ostracod characean stems and miliolid type benthic foraminifera that indicate a freshwater lacustrine depositional environment the total organic carbon toc values of the bituminous limestone samples range from 0 11 1 30 with an average toc value of 0 54 the hydrogen index hi varies from 119 448 mg hc g toc average hi 298 mg hc g toc indicating that the limestone contains gas prone as well as oil prone organic matter pyrolysis data prove that the organic matter content in the bituminous limestone consists of type ii kerogen the average tmax value for bituminous limestone samples is 438 c 434 448 c bitumen toc ratios for bituminous limestone are 0 05 and 0 04 the tmax values and the ratios indicate that the bituminous limestone samples contain early mature to mature organic matter analysis of solvent extracts from the two richest bituminous limestones show a predominance of high carbon number c26 c30 n alkanes the pr ph ratio and cpi value are 1 34 and 0 96 respectively c29 is the dominant sterane with c29 c27 c28 the bituminous limestone samples have low c22 c21 ratios high c24 c23 tricyclic terpane ratios and very low c31r c30 hopane ratios 0 25 these data are consistent with the bituminous limestones being deposited in a lacustrine environment

organic geochemistry of the lacustrine shales from the cretaceous taizhou formation in the gaoyou sag northern jiangsu basin abstract the shale from the cretaceous taizhou formation is an important source rock in the gaoyou sag northern jiangsu basin fifty three shale core samples analyzed for total organic carbon toc and rock eval pyrolysis analyses were used to evaluate the geochemistry of this shale twenty one samples of them were analyzed using solvent extraction extract fractionation gas chromatography mass spectrometer gc ms of the saturated fraction and organic petrology analyses based on the test results the shale of the taizhou formation contains mainly type ii iii organic matter and is chiefly oil prone and oil gas prone as a fair to good oil source rock with a small quantity of gas source rock vitrinite reflectance rock eval pyrolysis and biomarker suggest that in this sag the shale of the taizhou formation is mainly in the early mature stage and within the oil window so the shale generates chiefly liquid oil the gaoyou sag is an oil generating sag the saturated fraction and biomarker composition of the shale provide evidence that the taizhou formation shale was formed mainly in a reductive sedimentary environment with anoxic fresh to low salinity water the organic matter came chiefly from plankton and partly from land plants and bacterial organisms

organic geochemistry as an aid in the interpretation of the history of oil migration into different reservoirs at the hibernia k 18 and ben nevis i 45 wells jeanne d arc basin offshore eastern canada abstract the jeanne d arc basin is situated in the northeastern part of the grand banks off the east coast of newfoundland several large oil and gas fields have been discovered in this basin the largest of which is the giant hibernia field the principal source rock of most of the oils in the jeanne d arc basin is the kimmeridgian aged egret member of the rankin formation a characteristic feature of the biomarker distributions of both the oils and the egret member extracts is the very high abundance of 4 methyl steranes the high concentration of these compounds prevents the accurate measurement of maturity and other parameters based on 4 desmethyl steranes using gc ms sim the use of collision activated decomposition cad gc ms ms is demonstrated as a method of overcoming the problem of chromatographically co eluting compounds to obtain reliable biomarker data biomarker and other geochemical data are then used to help elucidate the history of oil migration into stacked reservoirs in two wells in the jeanne d arc basin all the hibernia k 18 oils are sourced from the egret member we interpret our data to indicate that all the reservoirs over a 1570 m depth interval were originally filled by a single pulse of oil that migrated vertically via faults in the lowermost hibernia reservoirs this event is being overprinted by more mature hydrocarbons leaking from the underlying overpressured zone with increasing depth at ben nevis i 45 oils show an increase in maturity and in the proportion of hydrocarbons that are derived from a source rock other than the egret member this second source is dominated by terrestrially derived organic matter oils are found in other wells in the jean d arc basin with similar characteristics all these wells are located in one small area of the basin and are in close proximity to the trinity fault

sinkholes and caves related to evaporite dissolution in a stratigraphically and structurally complex setting fluvia valley eastern spanish pyrenees geological geomorphological and environmental implications abstract evaporite karst and sinkhole development is analysed in a geologically complex area of ne spain including four evaporite units with different characteristics and affected by compressional and extensional tectonic structures the exposed paleosinkholes including remarkable early pleistocene paleontological sites provide valuable information on the subsidence mechanisms and reveal the significant role played by interstratal karstification in the area these gravitational deformation structures including hectometre scale bending folds and oversteepened normal faults strongly suggest that the present day compressional regime inferred in previous studies may be largely based on the analysis of non tectonic structures two gypsum caves ca 1 km long show that passages with restricted cross sectional area may produce large breccia pipes and sinkholes thanks to the removal of breakdown boulders by high competence episodic floods moreover the upward progression of cave ceilings by paragenesis and condensation dissolution contributes to increase the probability of sinkhole occurrence an inventory of 135 sinkholes together with their geological and geomorphological context has been developed this data base has been used to infer several properties of the sinkholes with practical implications a magnitude and frequency scaling relationship spatial distribution patterns dominant controlling factors and risk implications

mafalda an early warning modeling tool to forecast volcanic ash dispersal and deposition 1 forecasting the dispersal of ash from explosive volcanoes is a scientific challenge to modern volcanology it also represents a fundamental step in mitigating the potential impact of volcanic ash on urban areas and transport routes near explosive volcanoes to this end we developed a web based early warning modeling tool named mafalda modeling and forecasting ash loading and dispersal in the atmosphere able to quantitatively forecast ash concentrations in the air and on the ground the main features of mafalda are the usage of 1 a dispersal model named vol calpuff that couples the column ascent phase with the ash cloud transport and 2 high resolution weather forecasting data the capability to run and merge multiple scenarios and the web based structure of the procedure that makes it suitable as an early warning tool mafalda produces plots for a detailed analysis of ash cloud dynamics and ground deposition as well as synthetic 2 d maps of areas potentially affected by dangerous concentrations of ash a first application of mafalda to the long lasting weak plumes produced at mt etna italy is presented a similar tool can be useful to civil protection authorities and volcanic observatories in reducing the impact of the eruptive events mafalda can be accessed at http mafalda pi ingv it

karst in gypsum and its environmental impact on the middle ebro basin spain the middle ebro basin in characterised by strong evaporitic profiles from the miocene period and in which gypsum formations are predominant these groups of easy solubility produce in many areas typically karstic landforms although there are certain features specific to them the generated landforms appear on the surface as different morphological types of doline which very often develop on the alluvium deposited by the river ebro and its affluents on the agricultural land of the penaflor villamayor area the functional character of karst causes collapse dolines to appear after heavy storms and these are constantly filled in by farmers motorways and roads that cross these areas as also the industrial estates existing on the outskirts of zaragoza are affected by dissolution processes that bring about continual collapses the infiltration of water from unlined canals causes the generation of numerous dolines along canal banks

biological markers in bitumens and pyrolyzates of upper cretaceous bituminous chalks from the ghareb formation israel abstract the sterane and triterpane distributions of three bituminous chalks from the upper cretaceous ghareb formation israel were investigated both in the original extractable bitumens and in extracts obtained after pyrolysis of whole rock and isolated kerogen samples at 450 c pyrolysis was performed in a closed system under hydrous whole rock and anhydrous conditions isolated kerogens the carbon number distributions of steranes and triterpanes differ significantly between original bitumen and pyrolyzates unlike the bitumens in which diasteranes were not detected the anhydrous pyrolyzates contain small amounts of diasteranes the presence of water during pyrolysis leads to an increase of sterane isomerization the abundant formation of diasteranes and an increase of the 18 h trisnorneohopane 17 h trisnorhopane ratio sterane isomerization maturation parameters show a closer match between original bitumen and pyrolyzates after pyrolysis in a closed system when compared with an open system

biological marker characteristics of oils and asphalts from carbonate source rocks in a rapidly subsiding graben dead sea israel abstract a detailed gc ms study of biological marker compounds in the saturated and aromatic hydrocarbon fractions of oils and asphalts from the dead sea area israel provided decisive information to the solution of a long lasting controversy by showing that the asphalts are products of early generation in an immature stage from the same type of carbonate source rock which generated more mature oils the asphalts are not biodegraded residues of the oils oils from six different wells and asphalts from wells outcrops and a floating block from the dead sea all have very similar sterane and triterpane patterns they all lack rearranged steranes diasteranes indicating a carbonate source matrix and compare reasonably well with a sample of upper cretaceous bituminous chalk from nebi musa the main difference between the oils and the asphalts is a significantly higher triaromatic to mono plus triaromatic steroid hydrocarbon ratio in the former this is explained as a result of rapid subsidence and heating of their source rock close to the deep parts of the dead sea graben the oils thus were generated in the more deeply buried source rock blocks under the graben fill whereas the asphalts either originate from an immature source rock section closer to the graben rims or represent an earlier phase of generation and expulsion this study also provides general information on the evolution of biological markers in carbonate source rocks low activation energy processes like isomerisation of steranes appear to occur much faster at low temperatures than in shales the high sulfur content and less cross linking of the biogenic organic matter into a complex kerogen structure are suggested to be responsible for this care should be taken when using only sterane isomerisation to assess the maturity of hydrocarbons from carbonate rocks and of carbonate derived oils

multiple exhumation phases in the central pontides n turkey new temporal constraints on major geodynamic changes associated with the closure of the neo tethys ocean

2001 flank eruption of the alkali and volatile rich primitive basalt responsible for mount etna s evolution in the last three decades abstract since the early 1970s enhanced eruptive activity of mount etna has been accompanied by selective geochemical changes in erupted lavas among which a gradual increase of alkalis whose origin is still debated here we provide further insight into the origin of this recent evolution based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase poor primitive basalt that was extruded during a highly explosive flank eruption in july august 2001 two types of lava were erupted simultaneously along a n s fracture system trachybasalts from the upper vents 2950 2700 m were simply drained out by fracturing of the central volcanic conduit they are identical to summit crater lavas and contain mg poor olivines fo 70 72 with evolved and volatile poor melt inclusions that represent late stage crystallisation during shallow open conduit degassing in contrast plagioclase poor basalt 80 of total extruded through the lower vents 2550 2100 m derived from lateral dyke intrusion of a more primitive and volatile rich magma across the sedimentary basement this primitive melt is best preserved in rare fo 82 4 80 5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent its high dissolved contents of h 2 o 3 4 wt co 2 0 11 to 0 41 wt s 0 32 wt cl 0 16 wt and f 0 094 wt point to its closed system ascent from 400 to 250 mpa 12 to 6 5 km depth b s l however the predominance of euhedral olivine phenocrysts with common reverse zoning cores fo 76 78 and rims fo 78 80 and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting the few preserved inclusions in these olivines indicate pre eruptive storage of that magma body at about 5 km depth b s l in coherence with seismic data we propose that the 2001 flank eruption resulted from gradual overpressuring of etna s shallow plumbing system due to the influx of volatile rich primitive basalt that may have begun several months in advance we find that this basalt is much richer in alkalis 2 0 wt k 2 o and has higher s cl 2 0 but lower cl k and cl f ratios than all pre 1970s etnean lavas 1 4 wt k 2 o s cl 1 5 as further exemplified by melt inclusions in entrained olivine xenocrysts combining these new observations with previously published data we argue that the 2001 basalt represents a new alkali rich basic end member feeding mt etna only few amount of which had previously been extruded during a 1974 peripheral eruption and more recently during brief paroxysmal summit events over the last three decades this new magma has progressively mixed with and replaced the former k poorer trachybasalts filling the plumbing system leading to extrusion of gradually more primitive and alkali richer lavas its geochemical singularities cannot result from shallow crustal contaminations instead they suggest the involvement of an alkali richer but cl poorer arc type component during recent magma genesis beneath etna

investigation of the complex dynamics and structure of the 2010 eyjafjallajokull volcanic ash cloud using multispectral images and numerical simulations 1 we investigated the structure and evolution of the 2010 eyjafjallajokull volcanic cloud and its dispersal over iceland and europe integrating satellite multispectral images and numerical simulations data acquired by medium resolution imaging spectrometer meris and advanced spaceborne thermal emission and reflection radiometer aster have been analyzed to quantify the cloud extent and composition the vol calpuff dispersal code was applied to reconstruct the transient and 3 d evolution of the cloud source parameters estimated on the base of available a posteriori volcanological data sets have been used quantitative comparisons between satellite retrievals and modeling results were performed for two selected instants of time during the first and third eruptive phases on a regional scale sensitivity of the model to initial volcanological conditions has been analyzed at continental scale several complex non intuitive features of cloud dynamics have been highlighted and strengths and limitations of the adopted methods identified the main findings are the level of quantitative agreement between satellite observations and numerical results depends on ash cloud composition particle sizes and concentration with better agreement for smaller particles and higher concentrations the agreement between observations and modeling outcomes also depends on the temporal stability of volcanological conditions and the complexity of the meteorological wind field the irregular dispersion of ash as reconstructed from satellite data and numerical modeling can be well explained by the different response of particle sizes to strong vertical wind shear and by resuspension processes acting at ground level eruptive source conditions are the main source of uncertainty in modeling especially during an ongoing crisis and at long range scales

identification prediction and mitigation of sinkhole hazards in evaporite karst areas sinkholes usually have a higher probability of occurrence and a greater genetic diversity in evaporite terrains than in carbonate karst areas this is because evaporites have a higher solubility and commonly a lower mechanical strength subsidence damage resulting from evaporite dissolution generates substantial losses throughout the world but the causes are only well understood in a few areas to deal with these hazards a phased approach is needed for sinkhole identification investigation prediction and mitigation identification techniques include field surveys and geomorphological mapping combined with accounts from local people and historical sources detailed sinkhole maps can be constructed from sequential historical maps recent topographical maps and digital elevation models dems complemented with building damage surveying remote sensing and high resolution geodetic surveys on a more detailed level information from exposed paleosubsidence features paleokarst speleological explorations geophysical investigations trenching dating techniques and boreholes may help in investigating dissolution and subsidence features information on the hydrogeological pathways including caves springs and swallow holes are particularly important especially when corroborated by tracer tests these diverse data sources make a valuable database the karst inventory from this dataset sinkhole susceptibility zonations relative probability may be produced based on the spatial distribution of the features and good knowledge of the local geology sinkhole distribution can be investigated by spatial distribution analysis techniques including studies of preferential elongation alignment and nearest neighbor analysis more objective susceptibility models may be obtained by analyzing the statistical relationships between the known sinkholes and the conditioning factors chronological information on sinkhole formation is required to estimate the probability of occurrence of sinkholes number of sinkholes km2 year such spatial and temporal predictions frequently derived from limited records and based on the assumption that past sinkhole activity may be extrapolated to the future are non corroborated hypotheses validation methods allow us to assess the predictive capability of the susceptibility maps and to transform them into probability maps avoiding the most hazardous areas by preventive planning is the safest strategy for development in sinkhole prone areas corrective measures could be applied to reduce the dissolution activity and subsidence processes a more practical solution for safe development is to reduce the vulnerability of the structures by using subsidence proof designs

effects of the mineral matrix on the distribution of geochemical markers in thermally affected sedimentary sequences the distribution of geochemical markers in bitumen fractions both free and associated with minerals was studied in bituminous chalk and black shale samples upper cretaceous israel upper cretaceous west greenland affected by combustion metamorphism and the latter also by dyke intrusion the bitumen fractions were obtained by stepwise extraction in conjunction with stepwise dissolution of the carbonate and subsequently silicate minerals they show differences in their bulk composition and in the distribution of n alkanes alkylcyclohexanes isoalkanes isoprenoids steranes and triterpanes at low maturity in the country rocks the distribution of the biomarkers in the various bitumen fractions reflects mainly the source or organic matter and minerals detrival vs autochthonous associated during transport and sedimentation with increasing maturation processes take place like i the formation of hydrogen bonded associations of clay minerals with organic matter ii the isomerisation of steranes which reaches different degrees free bitumen carbonate associated silicate associated in the bituminous chalk while bound free in the black shales iii the formation of isoalkanes and alkylcyclohexanes which occur only in the mineral associated fractions the particular effects of mineral groups on the geochemical markers during sedimentation generation and primary migration necessitates the consideration of the composition of the mineral matrix for the interpretation of the geochemical markers the generation of hydrocarbons during maturation probably involves the mobilization of bitumen from minerals and kerogen

a genetic classification of sinkholes illustrated from evaporite paleokarst exposures in spain this contribution analyses the processes involved in the generation of sinkholes from the study of paleokarst features exposed in four spanish tertiary basins bedrock strata are subhorizontal evaporites and in three of the basins they include halite and glauberite in the subsurface our studies suggest that formation of dolines in these areas results from a wider range of subsidence processes than those included in the most recently published sinkhole classifications a new genetic classification of sinkholes applicable to both carbonate and evaporite karst areas is thus proposed with the exception of solution dolines it defines the main sinkhole types by use of two terms that refer to the material affected by downward gravitational movements cover bedrock or caprock and the main type of process involved collapse suffosion or sagging sinkholes that result from the combination of several subsidence processes and affect more than one type of material are described by combinations of the different terms with the dominant material or process followed by the secondary one e g bedrock sagging and collapse sinkhole the mechanism of collapse includes any brittle gravitational deformation of cover and bedrock material such as upward stoping of cavities by roof failure development of well defined failure planes and rock brecciation suffosion is the downward migration of cover deposits through dissolutional conduits accompanied with ductile settling sagging is the ductile flexure of sediments caused by differential corrosional lowering of the rockhead or interstratal karstification of the soluble bedrock the paleokarsts we analysed suggest that the sagging mechanism not included in previous genetic classifications plays an important role in the generation of sinkholes in evaporites moreover collapse processes are more significant in extent and rate in areas underlain by evaporites than in carbonate karst primarily due to the greater solubility of the evaporites and the lower mechanical strength and ductile rheology of gypsum and salt rocks

three common source rock evaluation errors made by geologists during prospect or play appraisals geologists are frequently called on to evaluate the source rocks associated with their exploration prospects or plays the three most common questions asked and answered about the source rock during project reviews are what s the total organic carbon toc what kerogen type does rock eval indicate and what maturity level does the vitrinite reflectance data point to the answers to these seemingly innocuous questions may in fact be providing a false sense of security about the source rock in question understanding how this line of questioning can lead you astray and make you the victim of the toc myth if i have high toc i have a good source rock the rock eval fallacy the rock eval data tell me what kind of kerogen is in my source rock and the vitrinite reflectance deficiency vitrinite reflectance will tell me if my source rock is generating is important some of the solutions to these problems include fully integrating toc and rock eval data supplementing rock eval data with pyrolysis gas chromatography and using burial history diagrams to help interpret vitrinite reflectance harry dembicki jr is a senior geological advisor for geochemistry in the geological technology group at anadarko petroleum corporation where he provides technical support to both exploration and development teams he holds a b s degree 1973 in geology from the state university college of new york at new paltz and a ph d 1977 in geology with emphasis in organic geochemistry from indiana university he previously worked as an organic geochemist for conoco and marathon

geochemistry of upper miocene lower pliocene source rocks in the hellenic fold and thrust belt zakynthos island ionian sea western greece abstract the southwestern margin of the hellenic fold and thrust belt situated along the southern edge of the dinarides albanides hellenides continental convergent zone has been studied in terms of its hydrocarbon generating potential the upper miocene lower pliocene tortonian to zanclean clastic sedimentary succession at zakynthos island provides an excellent opportunity to evaluate the source rock potential of such a system twenty seven mudstone samples were analyzed using organic geochemical techniques such as rock eval pyrolysis bitumen extraction open column chromatography and gas chromatography mass spectrometry the obtained data indicate that the sedimentary sequence contains units with sufficient organic material of good enough quality to be considered as potential source rocks the input of terrestrial organic material and associated gaseous generating potential is indicated by 1 rock eval pyrolytic yields and calculated values of hydrogen and oxygen indices 2 n alkane distribution with dominant long chain components 3 high terrigenous to aquatic organic material ratios 4 odd to even predominance values 5 low sulfur content and 6 occurrence of gammacerane the kerogen is immature as evidenced by 1 t max and production index values 2 odd to even predominance values 3 low diasterane to sterane and pr ph ratios 4 low 20s 20s 20r and sterane ratios and 5 presence of gammacerane

sensitivity of biomarker properties to depositional environment and or source input in the lower toarcian of sw germany abstract a sequence of lower toarcian sediments which are highly contrasting in their depositional environment over a 5 m depth interval has been investigated in detail for the variability of geochemical properties which are used for source characterization and oil to source correlation lower liassic marls are representative of a well aerated shallow water environment in contrast to the immediately overlying bituminous shales which are deposited under extremely reducing conditions various properties have been found to vary considerably within these two units amongst the most important are carbon isotopic composition of the kerogen the pristane phytane ratios nickel as opposed to vanadyl porphyrins and the c27 dia regular steranes although maturation within the profile does not change some of the maturation dependent biomarker properties such as the monoaromatic steroid side chain cracking and the tm ts ratio exhibit large changes which can be assigned to diagenetic processes another maturation dependent property the 20s 20r epimerization of c29 steranes exhibits smaller changes which could also be due to early diagenetic processes the study suggests that reducing and oxidizing conditions i e eh and ph in the sediment exert an influence on several biomarker precursor product pathways in maturation studies initial variations due to depositional conditions have therefore to be taken into account

insar based modeling and analysis of sinkholes along the dead sea coastline sinkholes commonly form by subsurface dissolution cavities that collapse after the overlying layers become mechanically unsupported sinkholes along the dead sea shorelines are preceded by associated with and followed by gradual surface subsidence that accompanies the cavities growth we exploit satellite radar interferometry interferometric synthetic aperture radar to resolve temporal and spatial relationships between gradual subsidence and sinkhole collapse the geometry of the deflating cavity roof is determined by elastic inverse modeling of the surface displacements a coulomb failure stress criterion is applied to calculate the stress field induced by the deflating cavity at the ground surface we find that the induced stress field favors generation of sinkholes at the perimeters of the subsiding areas rather than at their centers in agreement with field observations providing important information for sinkhole hazard assessment further our analysis suggests that short term deformation in consolidated gravel layers at shallow depths could be approximated by simple elastic modeling

subsidence hazard avoidance based on geomorphological mapping in the ebro river valley mantled evaporite karst terrain ne spain in the valley of the ebro river to the southeast of the city of zaragoza ne spain the dissolution of evaporite sediments gypsum halite and na sulphates which underlie alluvial deposits gives rise to numerous sinkholes these sinkholes are a potential hazard to human safety particularly where they develop in a catastrophic way even slow developing sinkholes are problematic as they damage urban and agricultural infrastructure necessitating costly repairs and vigilant maintenance to assist in developing avoidance strategies for these hazards the factors controlling sinkhole occurrence have been assessed using geomorphological maps produced from aerial photographs for 1956 and 1981 important controls on sinkhole development are found to include underlying geological structure manifest in preferred orientations of sinkholes on the azimuths n130 150e and n30 40e and the presence of glauberite in the groundwater flow path which apparently promotes accelerated gypsum dissolution perhaps surprisingly alluvium thickness does not appear to significantly correlate with the density of sinkholes on the floodplain in this area the maps for 1956 and 1981 reveal that both human activity and natural processes can serve to obscure the true density of sinkhole development for instance a large number of sinkholes which were conspicuous in 1956 have since been back filled by farmers in the most fluvially active zone of the ebro valley the meander belt the relatively low density of sinkholes compared with adjoining zones suggests that subsidence is being masked by morpho sedimentary dynamic processes aggradation and erosion careful geomorphological mapping for different time periods yields a much more accurate impression of the frequency of sinkhole development than would be gained from surveying currently visible sinkholes in the area of interest

geomorphology of the tertiary gypsum formations in the ebro depression spain abstract this paper reviews the current knowledge of the mainly karstic geomorphological features developed in the evaporitic formations of the ebro depression northern spain special emphasis is given to the recently published and unpublished scientific advances the gypsum formations of tertiary age have an extensive outcrop area within the ebro depression here their morphogenesis is controlled mainly by processes of surface and subsurface dissolution acting on the gypsum outstanding landforms in the gypsum terrain include saline lakes developed in flat bottom dolines saladas other characteristic morphologies include karren and gypsum domes which occur on a decimetre scale where the gypsum is covered by quaternary alluvial deposits the karstification processes are especially intense and cause subsidence phenomena karstic subsidence affects stream terraces mantled pediments and infilled valleys which in the region are called vales dissolution induced synsedimentary subsidence has produced interesting geological features which include significant thickening and deformation of the alluvial deposits in contrast to the rapid removal of gypsum by dissolution the amount of gypsum removed by erosion is low water erosion studies carried out on gypsiferous slopes of the ebro depression indicate that the sediment yield ranges from 0 59 to 7 82 t ha year this low yield results from the high infiltration capacity of the soils subsidence caused by gypsum dissolution has important socio economic consequences in the ebro depression the active alluvial karstification of the gypsum causes numerous sinkholes that are harmful to linear structures roads railway lines irrigation channels buildings and agricultural land unforeseen catastrophic subsidence also puts human lives at risk the benefits of such terrains include thickened alluvial deposits which act as valuable water reservoirs and which form excellent sources of aggregates fluvial valleys in this gypsiferous terrain commonly show an asymmetrical geometry with prominent gypsum scarps at one side these gypsum scarps are affected by numerous landslides these slope movements are hazardous may dam rivers and cause flooding of the alluvial plains

gypsum karstification induced subsidence effects on alluvial systems and derived geohazards calatayud graben iberian range spain abstract the karstification of the tertiary gypsum formations in the calatayud graben has given rise to synsedimentary and postsedimentary subsidence phenomena in both the neogene sediments of the endorheic graben fill and in the quaternary alluvial sediments deposited under exorheic conditions in the so called maluenda and perejiles areas covering 4 4 and 12 km 2 respectively the neogene sedimentary units stratigraphically above the gypsum have subsided due to the karstification of the underlying evaporites the maximum subsidence in both areas has reached at least 200 m the jalon jiloca perejiles alluvial system has been affected by karstic subsidence during its quaternary evolution ten stepped alluvial levels pediment terrace have been identified as a consequence of synsedimentary karstic subsidence the deposit of an alluvial level can be locally thickened changing in a short distance from less than 10 m to more than 100 m in thickness thus the deposit of an individual terrace can be locally superimposed on the deposits of older terraces the palaeokarst recorded in the sediments of the different alluvial levels shows how the karstic subsidence has controlled the dynamics of the sedimentary system the alluvial karstic subsidence is currently active in the flood plains affecting fluvial channels buildings communication ways irrigation ditches and the calatayud gypsum scarp

organic geochemistry of the lower cretaceous black shales and oil seep in the sinop basin northern turkey an oil source rock correlation study abstract in the sinop basin a thick liassic to quaternary sedimentary section is exposed a lower cretaceous aged caglayan formation crops out in the basin and consists of claystone siltstone sandstone marl and black coloured shale that exhibits a fair to good source rock potential an oil seep from the caglayan formation is located in the ekinveren region of the sinop basin the average total organic carbon toc values of two shale samples from the caglayan formation in the ekinveren and the burnuk sections ekin 8 bur 7 are 1 48 and 1 26 wt respectively and the hydrogen index hi values are 190 and 244 mghc g toc respectively the potential yield py value of the samples is 2 0 mghc g rock which indicates fair good hydrocarbon potential for the caglayan formation a unimodal n alkane distribution with dominant light end components is observed on the gas chromatograms of the shale samples from the caglayan formation low tar terrigenous aquatic organic matter ratios low c 19 c 20 c 23 tricyclic terpane ratios and a higher type ii kerogen content indicate that the shale samples predominantly contain marine organic matter the pr ph ratios of the shale samples are 1 39 and 0 89 respectively the pr ph values in combination with a high c 30 diahopane c 29 ts ratio imply a suboxic anoxic depositional environment for the caglayan formation the t max values of the ekinveren and burnuk shale samples are in the range of 425 432 c and 431 434 c respectively and the average t max values are 429 c and 433 c respectively based on the t max data the caglayan formation shales are immature early mature in the ekinveren location and early mature mature in the burnuk location the cpi values isoprenoid n alkane ratio 20s 20s 20r c 29 sterane and 22s 22s 22r c 32 homohopane ratios indicate that the shales from the burnuk location are more mature than those of the ekinveren location the large ucm unresolved complex mixture and low amounts of n alkanes and isoprenoid alkanes observed in the gas chromatogram of the oil seep indicate that the oil has been heavily biodegraded the m z 191 and m z 127 mass chromatograms of the samples from the caglayan formation and the ekinveren oil seep were similar in their distributions of tricyclic terpane c 23 dominant c 24 tetracyclic terpane norhopane hopane homohopane with dominant c 31 and a decreasing amount of the higher number homologues diasterane and pregnane the c 27 c 28 and c 29 sterane distributions for the oil and the shale samples were also similar demonstrating a c 27 c 29 c 28 relationship thus the biomarker data strongly indicate that the black shales and the ekinveren oil seep are related to each other in other words the oil has been derived from the caglayan formation

hydrocarbon generation potential of a lower permian sedimentary succession mount agony formation southern sydney basin new south wales southeast australia abstract this research presents a comprehensive approach on the hydrocarbon generation potential applied for the first time on the lower permian mount agony formation that is exposed in the southern sydney basin southeast australia thirty mudstone samples were collected and analyzed using different organic geochemical methods such as rock eval vi toc bitumens extraction and gc ms analysis attributes such as quantity quality and maturity of the organic matter were utilized to estimate the regional source rock potential the obtained data indicate that the examined samples have poor to good dominantly gas prone source rock potential and contain a mixed in origin organic matter the slight predominance of terrestrial organic material is indicated by the low odd to even predominance values slight predominance of higher n alkanes over short chain n alkanes oep25 33 cpi25 33 acl25 33 and tar values some availability of marine organic material is evidenced by the predominance of intermediate chain n alkanes and the low n c19 n c31 and n c24 n c24 ratios the analyzed sediments are thermally mature as suggested by the tmax pi oep 25 33 and cpi25 33 values the pr n c17 ph n c18 c30 moretane c30 hopane ts ts tm and c32s s r ratios as well as by the c30 moretane c30 hopane versus tm ts plot a mudstone rich siliciclastic source rock is implied by the c29 c30 hopane ratios and by the ts ts tm versus 23tricyclic hopane cross plot this research offers original organic geochemical data of a sedimentary succession that was not so far regarded as source rock this study adds to the knowledge available for the types of potential reserves in the southern sydney basin which are mostly focused on coal and coal seam gas resources

the respiratory health hazards of volcanic ash a review for volcanic risk mitigation studies of the respiratory health effects of different types of volcanic ash have been undertaken only in the last 40 years and mostly since the eruption of mt st helens in 1980 this review of all published clinical epidemiological and toxicological studies and other work known to the authors up to and including 2005 highlights the sparseness of studies on acute health effects after eruptions and the complexity of evaluating the long term health risk silicosis non specific pneumoconiosis and chronic obstructive pulmonary disease in populations from prolonged exposure to ash due to persistent eruptive activity the acute and chronic health effects of volcanic ash depend upon particle size particularly the proportion of respirable sized material mineralogical composition including the crystalline silica content and the physico chemical properties of the surfaces of the ash particles all of which vary between volcanoes and even eruptions of the same volcano but adequate information on these key characteristics is not reported for most eruptions the incidence of acute respiratory symptoms e g asthma bronchitis varies greatly after ashfalls from very few if any reported cases to population outbreaks of asthma the studies are inadequate for excluding increases in acute respiratory mortality after eruptions individuals with pre existing lung disease including asthma can be at increased risk of their symptoms being exacerbated after falls of fine ash a comprehensive risk assessment including toxicological studies to determine the long term risk of silicosis from chronic exposure to volcanic ash has been undertaken only in the eruptions of mt st helens 1980 usa and soufriere hills montserrat 1995 onwards in the soufriere hills eruption a long term silicosis hazard has been identified and sufficient exposure and toxicological information obtained to make a probabilistic risk assessment for the development of silicosis in outdoor workers and the general population a more systematic approach to multi disciplinary studies in future eruptions is recommended including establishing an archive of ash samples and a website containing health advice for the public together with scientific and medical study guidelines for volcanologists and health care workers

natural and human induced sinkholes in gypsum terrain and associated environmental problems in ne spain the central ebro basin comprises thick evaporite materials whose high solubility produces typically karstic landforms the sinkhole morphology developed in the overlying alluvium has been studied using gravimetry and ground penetrating radar gpr on stream terraces as well as analyzing the evolution of sinkhole morphologies observed in aerial photographs taken in 1928 1957 and 1985 the sinkhole morphologies give some idea of possible subsurface processes as well as an indication of the final mechanisms involve in sinkhole development on stream terraces and cover pediments the most commonly encountered dolines are bowl shaped in their morphology with both diffuse and scarped edges in contrast dolines developed in the gypsiferous silt infilled valleys have a funnel and well shaped morphology the diffuse edged bowl shaped dolines are developed through the progressive subsidence of the alluvial cover due to washing down of alluvial particles through small voids and cracks into deeper subsurface caves resulting in a decrease alluvial density future compaction of the alluvial cover will produce surface subsidences this type of dolines are associated with negative gravity anomalies in contrast the scarped edge dolines are formed by the sudden collapse of a cavity roof the cavities and cracks formed in the gypsum karst may migrate to the surface through the alluvial deposits by piping and they may subsequently collapse in this instance the cavities can be detected by both gravity and gpr anomalies where the voids are not deeper than 4 5 m from the surface these processes forming sinkholes can be enhanced by man induced changes in the groundwater hydrologic regime by both inflows due to irrigation ditch losses or pipe leakages and by outflows from pumping activities

sinkhole hazards along the eastern dead sea shoreline area jordan a geological and geotechnical consideration for the last four decades the level of the dead sea has been subjected to continual variation which among other important factors has led to the occurrence of much subsidence and many sinkholes in the southern dead sea area sinkhole activities occurred repetitively and were observed in open farms across roads near dwellings and near an existing factory thus causing a serious threat to the locals and farmers of the area and their properties this paper presents the main results from detailed geological and geotechnical studies of this area aerial photo interpretation and borehole drilling aided these studies parallel geophysical investigations vertical electrical sounding and seismic refraction and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon it was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the dead sea the development of subsurface cavities is associated mainly with the variation in the level of the dead sea over the four past decades the presence of regional salt intrusion under the surface of salt beds the fluctuation of the water table and continuous dissolution and the active tectonism of the area moreover this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future no practical engineering solution to this problem is feasible

an automatic procedure to forecast tephra fallout tephra fallout constitutes a serious threat to communities around active volcanoes reliable short term forecasts represent a valuable aid for scientists and civil authorities to mitigate the effects of fallout on the surrounding areas during an episode of crisis we present a platform independent automatic procedure with the aim to daily forecast transport and deposition of volcanic particles the procedure builds on a series of programs and interfaces that automate the data flow and the execution and subsequent postprocess of fallout models firstly the procedure downloads regional meteorological forecasts for the area and time interval of interest filters and converts data from its native format and runs the calmet diagnostic model to obtain the wind field and other micro meteorological variables on a finer local scale 3 d grid defined by the user secondly it assesses the distribution of mass along the eruptive column commonly by means of the radial averaged buoyant plume equations depending on the prognostic wind field and on the conditions at the vent granulometry mass eruption rate etc all these data serve as input for the fallout models the initial version of the procedure includes only two eulerian models hazmap and fall3d the latter available as serial and parallel implementations however the procedure is designed to incorporate easily other models in a near future with minor modifications on the model source code the last step is to postprocess the outcomes of models to obtain maps written in standard file formats these maps contain plots of relevant quantities such as predicted ground load expected deposit thickness and for the case of or 3 d models concentration on air or flight safety concentration thresholds

isomerization and aromatization of hydrocarbons and the paleothermometry and burial history of alberta foreland basin the hydrocarbon fractions extracted from 34 cretaceous shales from a cross section of the alberta basin have been analyzed using gas chromatography mass spectrometry particular attention has been paid to the extents to which three temperature dependent geochemical reactions have occurred isomerization of steranes at c 20 isomerization of hopanes at c 22 and aromatization of c ring monoaromatic steroid hydrocarbons estimates of the kinetic constants of these reactions have been published previously therefore constraints may be put on the maximum temperature experienced by the sediments and the time for which this temperature existed the subsidence history of the alberta basin is simulated using a lithospheric flexural model in which the lithosphere is downwarped by the loading of overthrusts in the adjacent cordilleran orogene when overthrusting ceases erosion of the overthrusted region lightens the load and the lithosphere rebounds causing uplift and erosion of the foreland basin major overthrusting and therefore deep burial occurred during the laramide orogeny of late cretaceous to mid tertiary time the extent of chemical reactions suggests that the present maturity of the cretaceous shales is almost entirely a reflection of burial and heating during the laramide orogeny in a manner that is consistent with the lithospheric flexural model for the basin the chemical reactions suggest that the paleogeothermal gradient increased systematically away from the foothills of the rocky mountains along the profile studied that a similar trend exists today suggests this situation has persisted at least since the early stages of the laramide orogeny this variation is best explained by advective heat transfer water entering the basin in the faulted and topographically higher foothills is heated at depth thereby depressing the geothermal gradient this hot water then migrates updip and away from the foothills to enhance the geothermal gradients in the edmonton area and beyond the route of the migrating hot water is similar to that taken by hydrocarbons from devonian and cretaceous source rocks in the deep basin updip to the oil and tar sand accumulations of alberta