hydrocarbon biomarkers of neoproterozoic to lower cambrian oils from eastern siberia the neoproterozoic era is of widespread geobiological interest because it marks the critical transition from a world of microbes to one where animals become an established feature of the landscape much research into this time period has focused on the ventilation of the oceans as this is widely considered a primary factor driving the diversification of complex multicellular life in this study proterozoic to cambrian aged oils from eastern siberia were analyzed for their hydrocarbon biomarker contents and compound specific carbon isotopes in order to further our understanding of the prevailing environment and its microbial and metazoan communities geochemically these oils are broadly comparable to those of the ediacaran cambrian sedimentary rocks and oils of the south oman salt basin organic matter in the source sedimentary rocks included significant contributions from green algae demosponges and bacteria including cyanobacteria and methanotrophic proteobacteria although the ages of the siberian oils and putative parent source rock intervals are poorly constrained the geochemical similarities between the ediacaran oman huqf and nepa botuoba katanga family of siberian oil samples are impressive leading to the inference that their source rocks are coeval on the other hand oils from the baykit high are distinctive likely older and possibly of cryogenian age

changes in co2 diffuse degassing induced by the passing of seismic waves abstract solfatara crater located in the campi flegrei caldera is a volcano with one of the highest degassing rates on earth more than 1500 t of co 2 released by diffusion or through vents here we investigated how this gas release can be disrupted by the passage of seismic waves we performed continuous soil co 2 flux measurements during the propagation of seismic vibrations in the range of 5 hz to 200 hz induced by a vibroseis truck the co 2 flux was continuously recorded using the accumulation chamber method the data show a temporary and drastic up to two fold increase in co 2 flux exclusively during the vibrations before returning to the initial flux values these transient variations are interpreted as fluidization of the surficial granular layer that releases the stored gas similar degassing processes might occur at a larger scale during earthquakes to cause temporary increases in the total gas outflow in volcanic or tectonic areas our findings are useful to better assess and monitor the potential hazard from sudden co 2 flux release during earthquakes as several cases of intoxication or death have already been related to volcanic degassing

paired carbon isotopic analysis of ordovician bulk carbonate δ 13 c carb and organic matter δ 13 c org spanning the great ordovician biodiversification event abstract paired measurements of bulk carbonate 13ccarb organic matter 13corg and their difference 13c can be used to estimate changes in isotopic fractionation through time as a function of o2 co2 in the atmosphere however because local scale processes can also affect 13c it is essential to compare sections from widely separated water masses here we present new 13corg data from ordovician carbonate rocks from the great basin oklahoma and appalachian basin and compare with published 13ccarb records from these sections and paired 13c values from other carbonate successions around north america these new data complement previous studies that focused on upper ordovician 13ccarb excursions and now provide a composite ordovician 13corg record new lower ordovician tremadocian stage 13corg data range from ca 26 to 28 decreasing throughout the lower middle ordovician floian dapingian stages to ca 29 to 31 13corg values remain at their lowest throughout the sandbian and are similar to other published upper ordovician sandbian katian 13corg data from north america 13c values from well preserved intervals generally vary between 26 to 28 throughout the lower to middle ordovician tremadocian to early darriwilian but increase to 31 during the mid late darriwilian and mid sandbian similar to published data from younger late ordovician positive 13c excursions known as the guttenberg gice and hirnantian hice events the overall 13c trend shows a 3 increase throughout the early middle ordovician and coincides with a previously interpreted period of ocean cooling and some of the earliest pulses of global biodiversity of marine invertebrates and planktonic organisms modeling studies predict that pco2 decreased during this time suggesting that the effect of pco2 on 13c may have been overwhelmed by other controls such as an in increase in po2 or a higher o2 co2 ratio during this biodiversification event

total fluxes of sulfur dioxide from the italian volcanoes etna stromboli and vulcano measured by differential absorption lidar and passive differential optical absorption spectroscopy the total flux of sulfur dioxide from the italian volcanoes etna stromboli and vulcano was determined using the differential absorption lidar technique the measurements were performed from an oceanographic research ship making traverses under the volcanic plumes with the lidar system sounding vertically by combining the integrated gas concentration over the plume cross section with wind velocity data it was possible to determine the total fluxes of so2 from the three volcanoes all measured within a 3 day period in september 1992 we found total fluxes of about 25 180 and 1300 t d for vulcano stromboli and etna respectively these data collected with an active remote sensing technique were compared with simultaneous recording with passive differential optical absorption spectroscopy doas using the sky radiation as the light source since the geometry of the light paths crossing the volcanic plume is not well defined in the passive measurements a correction to the doas data is required the so2 results are also compared with previously available data from correlation spectroscopy measurements lidar measurements on atomic mercury were also made for the plumes from stromboli and vulcano but the system sensitivity and range only allowed estimates of upper limits for the hg fluxes

fractionation processes affecting the stable carbon isotope signature of thermal waters from hydrothermal volcanic systems the examples of campi flegrei and vulcano island southern italy abstract the carbon isotopic composition of dissolved c bearing species is a powerful tool to discriminate the origin of carbon in thermal waters from volcanic and hydrothermal systems however the 13 c values of dissolved co 2 and tdic total dissolved inorganic carbon are often different with respect to the isotopic signature that characterizes the potential carbon primary sources i e deep hydrothermal reservoirs magmatic gases and organic activity the most commonly invoked explanation for such isotopic values is related to mixing processes between deep and shallow end members nevertheless experimental and empirical investigations demonstrated that isotopic fractionation due to secondary processes acting on the uprising fluids from the hydrothermal reservoirs is able to reproduce the measured isotopic values in this paper we investigated the chemistry of thermal waters collected at campi flegrei and vulcano island southern italy whose origin is related to interaction processes among magmatic gases meteoric water seawater and hosting rocks a special focus was dedicated to the 13 c values of dissolved co 2 13 c co2 aq and total dissolved inorganic carbon 13 c tdic the 13 c co2 aq and 13 c tdic values in the water samples from both these systems ranged from i those measured in fumarolic gases likely directly related to the deep hydrothermal magmatic reservoir and ii those typically characterizing biogenic co 2 i e produced by microbially driven degradation of organic matter a simple mixing model of the two end members apparently explaining these intermediate carbon isotopic values contrasts with the chemical composition of the dissolved gases on the contrary isotopic fractionation due to secondary processes such as calcite precipitation affecting hydrothermal fluids during their underground circulation seems to exhaustively justify both the chemical and isotopic data if not recognized these processes which frequently occur in volcanic and hydrothermal systems may lead to an erroneous interpretation of the carbon source causing an underestimation of the contribution of the hydrothermal magmatic fluids to the dissolved carbon species these results pose extreme caution in the interpretation of intermediate 13 c co2 aq and 13 c tdic values for the assessment of the carbon budget of hydrothermal volcanic systems

chemostratigraphy of the posidonia black shale sw germany ii assessment of extent and persistence of photic zone anoxia using aryl isoprenoid distributions aquatic depositional environments where anoxic conditions extend from bottom waters into the photic zone occurred frequently during the geologic past periods of photic zone anoxia pza can be recognized by the presence of specific lipids produced exclusively by the green sulphur bacteria chlorobiaceae that are preserved in the sedimentary record chlorobiaceae perform anoxygenic photosynthesis that requires light penetration into h2s saturated waters sediment samples integrate paleoenvironmental conditions over time intervals ranging from at best a few decades to more commonly several millennia photic zone anoxia recognized in paleoenvironmental analyses is thus defined as episodic with no further interpretation on the duration and persistence of the anoxic events we provide here a high resolution multiproxy chemostratigraphy study for the toarcian posidonia black shale from the dotternhausen section in sw germany in order to assess duration and seasonal fluctuation of photic zone anoxia based on the relative abundance of derivatives of chlorobiaceae lipids we assess the variability in the degree and persistence of photic zone anoxia using an aryl isoprenoid ratio air obtained by calculating the proportion of the short chain c13 17 versus the intermediate chain c18 22 aryl isoprenoids higher relative abundance of the short chain analogues is interpreted as indicating more intensive aerobic degradation of aryl isoprenoids air varies between values of 0 5 indicative of persistent pza phases and 3 0 for short termed episodic pza events absolute concentration of aryl isoprenoids is negatively correlated with the air which is in agreement with a progressive diagenetic breakdown of aryl isoprenoids the air decreases are validated using independent palecological and geochemical redox indicators for the posidonia shale in sw germany d 2004 elsevier b v all rights reserved

dynamics of vulcano island tyrrhenian sea italy investigated by long term 40 years geophysical data abstract vulcano island is a composite volcanic edifice located in the south central sector of the aeolian archipelago tyrrhenian sea italy historic activity has been characterized by frequent transitions from phreatomagmatic to minor magmatic activity the last eruption in 1888 90 saw powerful explosive pulses and this eruption defines what we call vulcanian also for other volcanoes since then volcanic activity has been in the form of fumarolic emanations of variable intensity and temperature mainly concentrated at la fossa crater we investigated vulcano dynamics through ca 40 years of ground deformation and seismicity data collected by the discrete and continuous ingv monitoring networks we considered levelling gps edm seismic and tilt data edm and levelling measurements began in the middle of the 1970s since the late 1990s the edm benchmarks have been measured using gps we performed a data inversion identifying for the 1999 2013 period the action of a deflating magmatic source located under vulcanello at 4 5 km a s l just at the top of a wide regional tectonic tabular source we analyzed data on different time space scales distinguishing the dynamics of different sectors of vulcano piano vulcanello la fossa cone and caldera and three periods 1974 1984 1984 1999 1999 2013 and the time evolution of the dynamics of the island we also show how the regional tectonic stress plays an important role in the transition of the volcanic system from a phase of stability to one of unrest inducing the heating and expansion of shallow hydrothermal fluids

magmatic degassing of multicomponent vapors and assessment of magma depth application to vulcano island italy degassing of magmatic h2o co2 and rare gases plays a major role in understanding large scale earth processes and in the assessment of volcanic activity here we describe a quantitative model for magmatic degassing of h2o co2 noble gas n2 mixtures our modeling takes into account non ideal behaviors by adopting recently developed approaches for the solubility of h2o co2 mixtures in silicate liquids and for noble gas partitioning in h2o co2 bearing magmas this new approach allows quantitative treatment of inert gas fractionation throughout the degassing of any h2o co2 bearing natural magma in a wide range of thermo baric conditions magma degassing simulations performed by our model have clearly displayed that dissolved h2o and co2 in the melt strongly affect inert gas degassing due to their modest solubility differences in h2o rich magmas all the inert gases are strongly partitioned into vapor at early degassing extents after the quick exhaustion of co2 in contrast co2 rich melts retain dissolved helium longer because co2 has firstly to be released from magma whereas nitrogen and heavy noble gases undergo a similar or higher exsolution than co2 at early magma degassing extents we have successfully applied the degassing model to the active volcanic system of vulcano island italy where several geochemical parameters have been monitored over the last decade by quantitatively assessing magma pressure over time the model has allowed us to reconstruct the rise of magma towards the surface the results clearly show that the magma has reached low pressure and depth beneath vulcano thus interaction with the hydrothermal system as well catastrophic magma rises may result in hazardous future scenarios

diffuse volcanic gas emission and thermal energy release from the summit crater of pico do fogo cape verde we report the first detailed study of diffuse emission of carbon dioxide co2 hydrogen sulfide h2s helium he and hydrogen h2 from the summit crater of pico do fogo volcano cape verde diffuse co2 h2s he and h2 gas fluxes were measured at 57 sampling sites and ranged up to 12 800 13 1 and 6 g m 2 day 1 respectively soil temperature measurements at each sampling site were used to evaluate the heat flux most of the summit crater shows relatively high co2 efflux with highest values close to the fumarolic area suggesting a structural control of the degassing process in contrast h2s effluxes were negligible or very low at the summit crater except close to the fumarolic area where anomalously high co2 efflux and soil temperatures were also measured we estimate total co2 h2s he and h2 diffuse gas fluxes of 219 t day 1 25 4 and 33 kg day 1 respectively based on a h2o co2 mass ratio of 1 52 measured at the fumaroles we estimate a diffuse steam flux from the summit crater of approximately 330 t day 1 the enthalpy of this steam is equivalent to a heat flux of about 10 3 mw the diffuse gas emission and thermal energy released from the summit crater of pico do fogo volcano are comparable to those observed at other volcanoes sustained surveillance of pico do fogo using these methods will be valuable for monitoring the activity of one of the most active volcanoes in the atlantic ocean

correlated increase in co2 fumarolic content and diffuse emission from la fossa crater vulcano italy evidence of volcanic unrest or increasing gas release from a stationary deep magma body 1 the peculiarity of the quiescent la fossa volcano is the occurrence of crises characterized by strong increases of fumarole t and output and by chemical changes indicative of an increasing input of magmatic fluids several surveys carried out during a new crisis began in november 2004 indicate that the total diffuse co2 emission for the crater area increases by one order of magnitude during crises up to 1600 ton d 1 in december 2005 concern exists on the possibility that these crises be related to an unrest process leading to eruption the repetition along decades of the same gas compositional variations during crises their temporal coincidence with increases of the local shallow seismicity and the lack of any significant ground motion rather suggest that they correspond to moments of increasing volatile release from a stationary magma system

geochemical character and origin of oils in ordovician reservoir rock illinois and indiana usa twenty three oils produced from reservoirs within the ordovician galena group trenton equivalent and one oil from the mississippian ste genevieve limestone in the illinois and indiana portions of the illinois basin are characterized two end member oil groups 1 and 2 and one intermediate group 1a are identified using conventional carbon isotopic analysis of whole and fractionated oils gas chromatography gc of saturated hydrocarbon fractions isotope ratio monitoring gas chromatography mass spectrometry irm gc ms of n alkanes ranging from c15 to c25 and gas chromatography mass spectrometry gc ms of the aromatic hydrocarbon fractions group 1 is characterized by high odd carbon predominance in mid chain n alkanes c15 c19 low abundance of c20 n alkanes and an absence of pristane and phytane group 1a is characterized by slightly lower odd carbon predominance of mid chain n alkanes greater abundance of c20 n alkanes compared to group 1 and no pristane and phytane the carbon isotopic composition of n alkanes and the distribution of n alkylarenes for groups 1 and 1a indicate that these oils were generated from strata containing abundant gloeocapsomorpha prisca in contrast group 2 is characterized by low odd carbon predominance in mid chain n alkanes moderate abundance of c20 n alkanes and the presence of pristane and phytane the mississippia reservoired oil is characterized by low odd carbon predominance in mid chain n alkanes and greater abundances of c20 n alkanes pristane and phytane compared to group 2 distributions of isoprenoidal alkylarenes aryl isoprenoids for group 2 and the mississippian reservoired oil are similar suggesting that aryl isoprenoids fail to provide a diagnostic characteristic that can be used to precisely correlate oils and source rocks conventional correlations of oil to source rock based on carbon isotopic type curves and hopane m z 191 and sterane m z 217 distributions are of limited use in distinguishing ordovician reservoired oil groups and determining their origin oil to source rock correlations using the distribution and carbon isotopic composition of n alkanes and the m z 133 chromatograms of n alkylarenes show that groups 1 and 1a originated from strata of the upper ordovician galena group group 2 either originated solely from the upper ordovician maquoketa group or from a mixture of oils generated from the maquoketa group and the galena group the mississippian reservoired oil most likely originated from the devonian new albany group the use of gc irm gc ms and gc ms illustrates the value of integr ted molecular and isotopic approaches for correlating oil groups with source rocks

lipid biomarker and stable isotopic profiles through early middle ordovician carbonates from spitsbergen norway abstract one of the most dramatic episodes of sustained diversification of marine ecosystems in earth history took place during the early to middle ordovician period changes in climate oceanographic conditions and trophic structure are hypothesised to have been major drivers of these biotic events but relatively little is known about the composition and stability of marine microbial communities controlling biogeochemical cycles at the base of the food chain this study examines well preserved carbonate rich strata spanning the tremadocian through upper dapingian stages from the oslobreen group in spitsbergen norway abundant bacterial lipid markers elevated hopane sterane ratios average 4 8 maximum of 13 1 detection of chlorobi markers in organic rich strata and bulk nitrogen isotopes 15ntotal averaging 0 to 1 for the open marine facies suggest episodes of water column redox stratification and that primary production was likely limited by fixed nitrogen availability in the photic zone near absence of the c30 sterane marine algal biomarker 24 n propylcholestane 24 npc in most samples supports and extends the previously observed hiatus of 24 npc in early paleozoic late cambrian to early silurian marine environments very high abundances of 3 methylhopanes average 9 9 maximum of 16 8 extends this biomarker characteristic to early ordovician strata for the first time and may reflect enhanced and sustained marine methane cycling during this interval of fluctuating climatic and low sulfate marine conditions olenid trilobite fossils are prominent in strata deposited during an interval of marine transgression with biomarker evidence for episodic euxinia anoxia extending into the photic zone of the water column

methylhopanoids molecular indicators of ancient bacteria and a petroleum correlation tool abstract methylhopanoids are organic compounds synthesized by certain bacteria that when preserved in sediments act as molecular fossils or biomarkers for organic matter inputs from specific bacterial sources two series of methylhopanoids occur each mainly deriving from a distinct bacterial source cyanobacteria 2 methyl and methanotrophic bacteria 3 methyl the abundance and composition of methylhopanoids within sediments of modern depositional environments varies widely apparently due to different bacterial communities contributing to the sedimentary organic matter comparable molecular characteristics are found in oils and their source rocks consequently methylhopanoids are valuable in oil oil and oil source rock correlations distinguishing between samples related to different depositional environments in particular abundant 3 methylhopanoids from methanotrophic bacteria or an additional unknown bacterial source are characteristic of some modern alkaline saline lake environments comparable compositional features in the methylhopanes of oils allow the assignment of lacustrine oils offshore west africa to two distinct lacustrine source rock facies and to distinguish between different marine source facies thus refining oil source rock correlation

distribution and structure of hydrocarbons in four organic rich ordovician rocks abstract organic matter in four north american rocks of ordovician age has been analysed using geochemical and optical techniques including reflected light and fluorescence microscopy rock eval pyrolysis elemental analysis of isolated kerogens gas chromatography gc and gas chromatography mass spectrometry gc ms of hydrocarbons in the solvent extracted bitumens the samples analysed were guttenberg oil rock and black shales from the vinini womble and big fork formations in the united states the origin of some of the biomarkers found in the bitumen and the vitrinite particles observed in reflected light are discussed briefly with reference to possible algal and bacterial precursors the results indicate that the four samples are potentially excellent oil source rocks although the guttenberg oil rock is too immature to have generated a substantial quantity of hydrocarbons

origin of the fumarolic fluids of vulcano island italy and implications for volcanic surveillance variations in d and 18o values with h2o contents and outlet temperatures indicate that the fumaroles of la fossa crater have discharged mixtures of magmatic water and marine hydrothermal water since 1979 the contribution of meteoric water was low in the period 1979 1982 and very low afterwards the 18o values of the marine hydrothermal component of 5 to 7 2 are due to isotopic exchange with the 18o rich silicates of the rocks under high temperature and low permeability conditions the 18o value of the magmatic end member is generally 3 5 to 4 3 although values as high as 5 5 to 6 5 were reached in the summer of 1988 when magma degassing appears to have extended into the core of the magma body the d values of the end member were close to 20 typical of andesitic waters both the isotopic values and chemical data strongly support a dry model consisting of a central magmatic gas column and a surrounding hydrothermal envelope in which marine hydrothermal brines move along limited fracture zones to undergo total evaporation on approaching the conduits of magmatic fluids the vents at the eastern and western boundaries of the fumarolic field are fed by fluids whose pressure is governed by the coexistence of vapor liquid and halite giving rise to a high risk of phreato magmatic explosions should magma penetrate into these wet environments most la fossa eruptions were triggered by an initial hydrothermal blast and continued with a series of phreatomagmatic explosions the fluids discharged by the forgia vecchia fumaroles are mixed with meteoric water which is largely evaporated although subordinate loss of condensed steam may be responsible for scrubbing most of the acidic gas species the temperatures and pressures and the risk of a sudden pressure increase are low a boiling hydrothermal aquifer at 230 c is present underneath the baia di levante beach this area has a minor risk of hydrothermal explosions

n2 fixing cyanobacteria supplied nutrient n for cretaceous oceanic anoxic events the abundance of specific membrane lipids 2 methylhopanoids indicates that cyanobacteria played a key role in the seemingly global deposition of black shales during the early aptian ca 120 5 ma and late cenomanian ca 93 5 ma oceanic anoxic events organic matter rich sediments deposited during these events are characterized by a 15n content typical of newly fixed n2 indicating that cyanobacterial n2 fixation was the main source for nutrient n we propose that denitrification and anaerobic ammonium oxidation effectively cut off the return of nutrient n from the anoxic deep waters to the photic zone in the oceans giving n2 fixing cyanobacteria a competitive advantage over algae during these oceanic anoxic events

diffuse volcanic degassing and thermal energy release from hengill volcanic system iceland we report the first detailed study of spatial variations on the diffuse emission of carbon dioxide co2 and hydrogen sulfide h2s from hengill volcanic system iceland soil co2 and h2s efflux measurements were performed at 752 sampling sites and ranged from nondetectable to 17 666 and 722 g m 2 day 1 respectively the soil temperature was measured at each sampling site and used to evaluate the heat flow the chemical composition of soil gases sampled at selected sampling sites during this study shows they result from a mixing process between deep volcanic hydrothermal component and air most of the diffuse co2 degassing is observed close to areas where active thermal manifestations occur northeast flank of the hengill central volcano close to the nesjavellir power plant suggesting a diffuse degassing structure with a ssw nne trend overlapping main fissure zone and indicating a structural control of the degassing process on the other hand h2s efflux values are in general very low or negligible along the study area except those observed at the northeast flank of the hengill central volcano where anomalously high co2 efflux and soil temperatures were also measured the total diffuse co2 emission estimated for this volcanic system was about 1 526 160 t day 1 of which 453 t day 1 29 7 are of volcanic hydrothermal origin to calculate the steam discharge associated with the volcanic hydrothermal co2 output we used the average h2o co2 mass ratio from 12 fumarole samples equal to 88 6 range 9 4 240 2 as a representative value of the h2o co2 mass ratios for hengill fumarole steam the resulting estimate of the steam flow associated with the gas flux is equal to 40 154 t day 1 the condensation of this steam results in thermal energy release for helgill volcanic system of 1 07 1014 j day 1 or to a total heat flow of 1 237 mwt

organic matter source variation and the expression of a late middle ordovician carbon isotope excursion the carbon isotopic composition of organic matter is a powerful tool in the study of organic carbon burial and p co 2 through the geologic record however the organic matter source can affect total organic carbon 13 c values and may complicate interpretation of environmental conditions we examined the influence of organic matter source variations on a late middle ordovician positive 13 c excursion in strata of the united states midcontinent in a core from iowa the magnitude of the excursion recorded by carbonate carbon is 2 5 whereas the excursion recorded by total organic carbon is nearly 8 although this difference could arise from a profound decrease in surface water co 2 concentrations association of the organic walled microfossil gloeocapsomorpha prisca with 13 c enriched total organic carbon toc in this interval suggests that the excursion could also record a shift from normal marine to g prisca dominated organic matter carbon isotope analyses of individual biomarkers indicate that both of these explanations are required to explain the data compounds inferred to be of g prisca origin are enriched in 13 c by 7 relative to compounds derived from other algal sources furthermore compounds exclusively from either g prisca or other sources exhibit a positive shift of only 3 5 thus the large excursion recorded by toc reflects in part a change in the proportional contribution of g prisca to toc that all compounds exhibit a positive carbon isotopic shift indicates that independent of contributions from g prisca a positive organic 13 c excursion occurred and records a change in environmental conditions such as co 2 aq concentrations the 3 5 shift is similar in magnitude to that observed for toc in correlative units from pennsylvania suggesting that this event has broad geographic significance this work illustrates that organic matter source variations as well as environmental conditions govern the toc 13 c values and shows how compound specific isotope analyses can resolve these multiple controls

temporal variations in air permeability and soil co2 flux in volcanic ash soils island of vulcano italy air permeability is a major physical factor affecting the advective transport of a gas through the soil and variations in this parameter can strongly influence the emission of endogenous gases from the soil to the atmosphere in this paper we illustrated a new and simple method for measuring in situ air permeability based on the measurement of air pressure inside a special probe inserted into the soil the method was designed and developed primarily to study the relationship between air permeability and the soil co2 flux in an active volcanic area the method was used for continuous monitoring of the air permeability at two different locations on the island of vulcano at the same time the values of the atmospheric pressure temperature rain and volumetric water content of the soil were also acquired to investigate their effect on soil air permeability and soil co2 flux the results showed that during the monitoring period soil air permeability exhibited minor variations at each site while larger variations in the soil co2 flux were recorded the effect of soil air permeability on soil co2 flux was negligible at both sites whereas a strong dependence of soil co2 flux on volumetric water content and on atmospheric pressure was found furthermore the variation in air permeability recorded at both sites was much lower than that predicted using some well known predictive models showing that the relationship among different soil transport parameters is more complex in real field conditions than would be expected by semiempirical models

key factors controlling hydrocarbon accumulations in ordovician carbonate reservoirs in the tazhong area tarim basin western china abstract the tazhong area at the center of the tarim basin western china contains abundant hydrocarbon resources principally in ordovician carbonate reservoirs the geological conditions for hydrocarbon accumulation in the area are quite complicated and are characterized by multiple stages of hydrocarbon generation accumulation adjustment and alteration despite decades of exploration and production in the region the mechanisms of hydrocarbon accumulation and their controlling factors are still not well established the geological setting and the distribution characteristics of the reservoir have been used to investigate the mechanisms of accumulation to quantitatively describe the main controlling factors and to predict potential favorable hydrocarbon accumulation zones in ordovician carbonate rocks of tazhong our results show that the hydrocarbons in the ordovician reservoirs came from mixed sources including middle lower cambrian and middle upper ordovician source rocks within the majiaer sag four stages of accumulation are recognized and hydrocarbons migrated into the tazhong area along six intersections of ne and nw fault sets principally from the northeast to the southwest but then locally from the northwest to the southeast the ordovician carbonate reservoirs are typically lithologically defined and the dynamic force of hydrocarbon accumulation is primarily reflects differential capillary forces the accumulation and distribution of hydrocarbons was controlled by the petrophysical properties of the reservoir and by hydrocarbon supply charge energy the petrophysical properties of the reservoir controlled the hydrocarbon accumulation threshold with the maximum differential capillary pressure force on average approximately 13 mpa the supply or charge energy of the hydrocarbons controls the accumulation distribution range the daily production of individual wells decreases with increasing distance from the fault intersections and the maximum hydrocarbon migration distance is about 35 km reservoir properties and the hydrocarbon supply charge energy coupling index rei appear to control hydrocarbon accumulation and distribution accumulation does not occur when the value of rei is 0 6 but is favored when values are higher

time series analysis of high temperature fumaroles monitored on the island of vulcano aeolian archipelago italy abstract the exhalation activity at the la fossa cone vulcano island aeolian archipelago italy has been ongoing for more than 1 century many of the monitored geochemical and geophysical parameters have showed transient variations of energy release the time series analyses of fumarole temperatures presented in this paper enabled the sequence of observations to be defined and information from different monitoring stations to be integrated the motion of fluids feeding the fumaroles of the la fossa cone is driven by the thermal and kinetic energies that balance the seismic and volcanic forces active in the region and the temperatures of the fumaroles reflect the local response of the hydrothermal system to these forces during a 14 year period of observation from 1998 to 2012 fumarole temperatures showed various trends but also cyclic variations characterized by sharp increases the repetition of these variations during periods with different trends indicates that no physical variation occurred from the hydrothermal source to the surface during the analyzed period and after each periodic geochemical crisis the previous thermal conditions were restored although the continuous monitoring of high temperature fumaroles was limited to only a few sites the observed trends characterized the most important fumaroles in the area of vulcano island an evaluation of thermal energy release based on these spatially discrete measurements would be a speculative exercise in thermodynamics but the analyses of the recorded data represent a step forward in interpreting the signals from ongoing volcanic activity and in assessing the seismic risk

high resolution isotope stratigraphy of the lower ordovician st george group of western newfoundland canada implications for global correlation the lower ordovician st george group of western newfoundland consists mainly of shallow marine platform carbonates 500 m thick it is formed from bottom to top of the watts bight boat harbour catoche and aguathuna formations the top boundary of the group is marked by the regional st george unconformity outcrops and a few cores from western newfoundland were sampled at high resolution and the extracted micritic materials were investigated for their petrographic and geochemical criteria to evaluate their degree of preservation the d13c and d18o values of wellpreserved micrite microsamples range from 4 2 to 0 vpdb and from 11 3 to 2 9 vpdb respectively the d13ccarb profile of the st george group carbonates reveals several negative shifts which vary between 2 and 3 and are generally associated with unconformities disconformities or thin shale interbeds thus reflecting the effect of or link with significant sea level changes the st george unconformity is associated with a negative d13ccarb shift 2 on the profile and correlated with major lowstand around the end of arenig on the local sea level reconstruction and also on those from the baltic region and central australia thus suggesting that the st george group unconformity might have likely had an eustatic component that contributed to the development enhancement of the paleomargin other similar d13ccarb shifts have been recorded on the st george profile but it is hard to evaluate their global extension due to the low resolution of the documented global lower ordovician tremadoc middle arenig d13ccarb profile

did cooling oceans trigger ordovician biodiversification evidence from conodont thermometry the ordovician period long considered a supergreenhouse state saw one of the greatest radiations of life in earth9s history previous temperature estimates of up to 70 c have spawned controversial speculation that the oxygen isotopic composition of seawater must have evolved over geological time we present a very different global climate record determined by ion microprobe oxygen isotope analyses of early ordovician silurian conodonts this record shows a steady cooling trend through the early ordovician reaching modern equatorial temperatures that were sustained throughout the middle and late ordovician this favorable climate regime implies not only that the oxygen isotopic composition of ordovician seawater was similar to that of today but also that climate played an overarching role in promoting the unprecedented increases in biodiversity that characterized this period

chemical and isotopic properties of kukersites from iowa and estonia abstract kukersite samples from estonia and iowa were analyzed for elemental composition functional group distribution and carbon and hydrogen stable isotope ratios the elemental and hydrogen isotope values together with other analytical data suggest a higher thermal maturity for the iowa kukersite the wide carbon isotopic range of 9 3 among kukersites with unusually negative 13c values reaching 33 2 indicates isotopically variable carbon sources for production of biomass and thus major paleoceanographic differences between the environments supporting biosynthesis

distinguishing cambrian from upper ordovician source rocks evidence from sulfur isotopes and biomarkers in the tarim basin abstract the reported source rocks for the abundant petroleum in the tarim basin china range from cambrian to lower ordovician and or upper ordovician in age however the difference between the two groups of source rocks is not well characterized in this study pyrite was removed from eleven mature to over mature kerogen samples from source rocks using the method of crcl 2 reduction and grinding the kerogen and coexisting pyrite samples were then analyzed for 34 s values results show that the kerogen samples from the cambrian have 34 s values between 10 4 and 19 4 the values are significantly higher than those from the lower ordovician kerogen 34 s of between 6 7 and 8 7 which in turn are generally higher than from the upper ordovician kerogen samples 34 s of between 15 3 and 6 8 the associated pyrite shows a similar trend but with much lower 34 s values this stratigraphically controlled sulfur isotope variation parallels the evolving contemporary marine sulfate and dated oil 34 s values from other basins suggesting that seawater sulfate and source rock age have an important influence on kerogen and pyrite 34 s values the relatively high 34 s values in the cambrian to lower ordovician source rocks are associated with abundant aryl isoprenoids gammacerane and c 35 homohopanes in the extractable organic matter indicating that these source rocks were deposited in a bottom water euxinic environment with water stratification compared with the upper ordovician the cambrian to lower ordovician source rocks show abundance in c 28 20r sterane c 23 tricyclic terpanes 4 23 24 trimethyl triaromatic dinosteroids and depletion in c 24 tetracyclic terpane c 29 hopane thus 34 s values and biomarkers of source rock organic matter can be used for distinguishing the cambrian and upper ordovician source rocks in the tarim basin

the end ordovician glaciation and the hirnantian stage a global review and questions about late ordovician event stratigraphy abstract this paper proposes a global review of hirnantian event stratigraphy the hirnantian gssp in south china is tentatively correlated with latest ordovician strata from the peri gondwanan glacial regions problems of biostratigraphical correlation are highlighted at a worldwide scale the major biostratigraphically useful fossil groups graptolites chitinozoans brachiopods conodonts acritarchs are analysed and their limits for global correlation of the uppermost ordovician are discussed palaeobiogeographical disparities are invoked as the primary cause of the difficulty in establishing an effective late ordovician global biostratigraphical scheme as an alternative correlative tool the hice hirnantian isotopic curve excursion event is often put forward in the literature however carbon isotope chemostratigraphy shows like biostratigraphy some limits to the present state of knowledge no good independent biostratigraphical control of the hice exists in both shallow carbonate deposits and deeper shaly ones recent studies have also demonstrated inconsistencies between carbon isotopic signals obtained from organic 13corg and inorganic 13ccarb carbon species further complicating the use of the hice as an isochronous benchmark all of these difficulties for hirnantian event stratigraphy are discussed in detail in order to enable them to be overcome in the future precise late ordovician and early silurian event stratigraphies are essential for the understanding of the mechanisms linked to the first of the big five extinctions

geochemical and seismological investigations at vulcano aeolian islands during 1978 1989 both geochemical and geophysical evidence indicates that the activity of the fumarolic system of the fossa crater can be divided into two periods from 1978 to 1983 such activity has been mainly controlled by two competing processes which affect the permeability of the fumarolic system at deep levels 1 rock fracturing induced by faulting and 2 mineral deposition alteration the latter which causes a slow decrease of the permeability at deep levels through clogging of fractures and voids prevailed at the end of this period determining a fluid pressure increment in the deep parts of the system from 1984 to 1989 fluid pressure at deep levels remained persistently high triggering local microseismic swarms furthermore pt conditions much higher than before were attained in the zones where hydrothermal fluids seep into the conduits from lateral aquifers owing to an uprising of the isotherms a deepening of these seeping zones or both

high resolution carbon isotopic records from the ordovician of south china links to climatic cooling and the great ordovician biodiversification event gobe abstract the great ordovician biodiversification event gobe represented the largest increase in diversity in the marine biosphere during the phanerozoic eon yet its causes and consequences remain poorly understood patterns of isotopic variation in high resolution 13ccarb and 13corg records from a well exposed section at honghuayuan in south china may provide important insights regarding the gobe the honghuayuan isotopic profiles which can be correlated with c isotopic records from contemporaneous sections globally reveal large perturbations to the global carbon cycle during the ordovician a 8 increase in 13corg values in the floian implies a large albeit transient increase in the burial rate of organic matter during the mid early ordovician that may have contributed to climatic cooling and played an important role in triggering the gobe a 4 increase in 13ccarb and high frequency variation in 13corg in the darriwilian to sandbian suggest a second episode of elevated organic carbon burial rates accompanied by substantial instability in the global carbon cycle during the late middle and early late ordovician this pattern may mark the onset of climate changes culminating in the end ordovician hirnantian glaciation and mass extinction event that terminated the gobe

carbon chemostratigraphy of the cambrian ordovician transition in a midlatitude mixed platform montagne noire france the cambrian drumian carbon isotope excursion dice and the steptoean positive carbon isotope excursion spice have been so far reported in subtropical platforms the dice event is a large negative excursion in 13ccarb record that nearly coincides with the beginning of the drumian cambrian series 3 whereas the spice event is a large positive shift in 13ccarb identified close to the base of the paibian furongian series the chemostratigraphic excursions have been recognized in carbonate dominated platforms and their application to mid and high latitude siliciclastic dominated platforms has been problematic this paper offers for the first time a high resolution stratigraphic analysis of this time span in a temperate water platform montagne noire france that recorded episodes of carbonate productivity in nearshore environments two sections were analyzed in detail a complete cambrian series 3 tremadocian succession devoid of carbonate interbeds and paleogeographically located in the distal part of the platform pardailhan nappe and a furongian tremadocian succession which has limestone interbeds and represents the proximal part of the platform minervois nappe the lower part of the la gardie formation in the pardailhan nappe displays background 13corg values of 22 punctuated by a large negative middle languedocian regional substage shift peaking at 24 5 this negative excursion is similar to the dice event reported close to the base of the drumian although the latter is exclusively based on 13ccarb values stable isotopes of 13ccarb and 13corg from both sections also indicate a common chemostratigraphic shift at the onset of the furongian in nearshore deposits of the minervois nappe the 13ccarb background values for the interbedded limestone strata of the val d homs formation gradually increase from 3 to 1 and are punctuated by a sharp increase in 13ccarb values to 3 0 by contrast in basinal shales of the la gardie formation in the pardailhan nappe the 13corg background values decrease from 22 to 27 1 this trend is directly controlled by total organic carbon toc contents and is interpreted to have been initiated by changes in the degree of biodegradation of organic matter sulfate reduction and methanogenesis before or soon after burial despite this overprinting and the very low degree of metamorphism reached by the shales the 13corg background trend is also punctuated by a sharp positive shift in 13corg values to 4 0 similar to the spice event in addition the asymmetric shape of the spice excursion in the montagne noire shows evidence for the herb event a late furongian negative carbon isotope excursion not yet accepted as a worldwide chemostratigraphic anomaly the recognition of both chemostratigraphic shifts in mixed and clayey strata opens new possibilities of chemostratigraphic correlation in mid and high latitude platforms where carbonate factories did not widely develop and strata only contain endemic fauna this implication has a major consequence because the global stratotype section and point gssp of the drumian and paibian stages occurs near the base of both excursions

seismic events at vulcano italy during 1988 1992 abstract a classification of seismic events is proposed that originate on vulcano aeolian islands southern tyrrhenian sea and adjacent regions into four broad classes 1 shocks that exhibit single peaked spectra 2 typical earthquakes with distinct p and s phases 3 irregular shaped events with ill defined to undetectable s phases and 4 long period events with dominant frequency peak less than 2 hz a hypothesis is put forward that the shocks occurring within the volcanic cone of la fossa are mainly related to intense fumarolic activity of high temperature more than 650 c in october 1992 estimation of seismic energy release within two distinct sectors one including la fossa cone the other external to it during 1988 1992 has been developed in order to evaluate the level of seismic activity of the system over the time here analysed the rate of seismic energy density release at la fossa was 4 71 1014 erg km 2 yr 1 that is significantly larger than that of the surrounding areas furthermore the energy partition estimate indicates that within la fossa seismic energy release associated with rock failure processes is on the whole about 3 6 times larger than that of fluid driven shocks the latter appear to be concentrated at rather shallow depths 400 1000 m where geochemical analyses and geothermal surveys indicate the sealing action of hydrothermal minerals estimated b values of the gutenberg richter magnitude frequency relation range between 0 81 0 27 and 1 45 0 29 within la fossa whereas a value around 1 6 has been calculated for the external sector the comparison between data presented in this paper and those from recent geophyical and geochemical investigations shows that appreciable increments in the rate of seismicity are accompanied with significant modifications in the chemistry of fumarolic gases and in the ground deformation pattern recorded at the base of the active cone

continuous monitoring of hydrogen and carbon dioxide at mt etna article i nfo this study assessed the use of an h2 fuel cell as an h2 selective sensor for volcano monitoring the resolution repeatability and cross sensitivity of the sensor were investigated and evaluated under known laboratory conditions a tailor made device was developed and used for continuously monitoring h2 and co2 at mt etna throughout 2009 and 2010 the temporal variations of both parameters were strongly correlated with the evolution of the volcanic activity during the monitoring period in particular the co2 flux exhibited long term variations while h2 exhibited pulses immediately before the explosive activity that occurred at mt etna during 2010

carbon isotope record of late cambrian to early ordovician carbonates of the argentine precordillera a more than 2000 m thick cambrian ordovician carbonate platform succession developed on the exotic argentine precordillera terrane during rifting from laurentia and drifting towards gondwana on base of these carbonates a carbon isotope curve could be developed for the cambrian ordovician we measured 13ccarb and 13corg values on bulk rocks selected components and diagenetic cements whereas the carbon isotope signals of intertidal and supratidal rocks are altered by diagenesis most subtidal carbonates exhibit primary marine values we can report reliable curves for the middle late cambrian transition and for the latest cambrian to earliest middle ordovician the 13c curve matches well with the published data from global cambrian ordovician boundary sections excursions and shifts in the carbon isotope curve correspond to events in sequence stratigraphy this indicates the interdependence on sea level which rules the productivity and or preservation of organic carbon and therefore the partition between corg and ccarb burial

ground deformation induced by geothermal processes a model for la fossa crater vulcano island italy 1 since the last eruption in 1888 1890 volcanic activity at vulcano island aeolian archipelago italy has been limited to fumarolic degassing concentrated near the active cone of la fossa crater in the northern sector of the island during the period 1990 1996 edm and leveling data indicate a deflation and contraction focused on the la fossa cone we jointly inverted these data sets using for volume change both a spherical mogi 1958 source and an ellipsoid as defined by davis 1986 the best fitting source for the 1990 1996 deflation is a shallow subvertical prolate ellipsoid positioned roughly under the crater our model is consistent with increased activity in a shallow hydrothermal system supported by observations of water evaporation testified by the increase of steam emission and temperature at crater fumaroles the fluid loss from a shallow geothermal reservoir is the most likely cause of the subsidence recorded at la fossa cone during the same period this clear linkage between the deformation signals and hydrothermal activity has important implications in the hazard assessment and monitoring of the vulcano activity

structural features of the shallow plumbing system of vulcano island italy in this study we integrate information gathered from surface geology and tectonics with the results of a shallow 0 2 km b s l seismic tomography of vulcano island italy obtained from the analysis of local earthquakes the observed low vp regions correspond to caldera filling products mainly consisting of pyroclastics tuffs lava flows and hyaloclastites high velocity anomalies represent intrusive bodies the striking correspondence between the stratigraphy from deep wells and the calculated velocity structure allows us to reconstruct the geometry and distribution of a main intrusion and to recognize some intra caldera depressions the shape and location of the high and low vp anomalies are consistent with nw se and n s strikes eruptive centres younger than 42 kyr as well as the structural depressions of vulcano and of the neighbour lipari island align along a n s direction the combined interpretation of the available structural data and of the results from the tomography suggests that magmatic reservoirs of vulcano at shallow depth 0 5 km align along a nw se strike but their shape is controlled by n s striking normal faults and or cracks that accommodate the right lateral movements of the nw se strike slip fault system

sterane biomarkers as indicators of palaeozoic algal evolution and extinction events abstract algae are among the oldest organisms known to inhabit the earth s biosphere with a record dating back some 2 7 ga only few marine algae produce hard parts that can be preserved over geologic time and consequently their fossil record is incomplete molecular fossils or biomarkers add complementary information to the fossil palynomorph record steroids are important constituents of eukaryotic cell membranes and are preserved in sediments as steranes c28 and c29 steranes are indicators for the presence of green and c27 steranes for the presence of red algae respectively the relative abundance of steranes allows the investigation of the fossil record for palaeozoic algal diversification and evolution in this study 500 palaeozoic rock samples representing a broad facies variety from the upper ordovician to the p t boundary were investigated for sterane compositions in addition three profiles covering the hirnantian the f f and the hangenberg event were analyzed for possible shifts in the sterane distribution associated with extinction events a sharp increase of the c28 c29 sterane ratio from 0 70 at the devonian carboniferous boundary implies a fundamental change in the green algae assemblage from more primitive mainly c29 sterane producing algae to modern c28 sterane producing algae for all investigated extinction events a pronounced but short lived rise in the c28 sterane content occurs that is attributed to an episodic increase in prasinophytes the gradual radiation of algae may have been triggered by frequent mass extinctions in the upper devonian culminating with the massive decline of acritarchs at the d c boundary the coeval rise in the c28 c29 sterane ratio indicates the presence of an non encysting algal group and coincides with the global augmentation of numerous filamentous codiacea siphonales and the rise of euspondyle and metaspondyle dasycladales

h2s fluxes from mt etna stromboli and vulcano italy and implications for the sulfur budget at volcanoes abstract we present here new measurements of sulfur dioxide and hydrogen sulfide emissions from vulcano etna and stromboli italy made by direct sampling at vents and by filter pack and ultraviolet spectroscopy in downwind plumes measurements at the f0 and fa fumaroles on vulcano yielded so 2 h 2 s molar ratios of 0 38 and 1 4 respectively from which we estimate an h 2 s flux of 6 to 9 t d 1 for the summit crater for mt etna and stromboli we found so 2 h 2 s molar ratios of 20 and 15 respectively which combined with so 2 flux measurements suggest h 2 s emission rates of 50 to 113 t d 1 and 4 to 8 t d 1 respectively we observe that source and plume so 2 h 2 s ratios at vulcano are similar suggesting that hydrogen sulfide is essentially inert on timescales of seconds to minutes this finding has important implications for estimates of volcanic total sulfur budget at volcanoes since most existing measurements do not account for h 2 s emission

anomaly threshold estimation and data normalization using eda statistics application to lithogeochemical exploration in lower cretaceous zn pb carbonate hosted deposits northern spain abstract a lithogeochemical survey of lower cretaceous sediments 1293 samples in the basque cantabrian basin northern spain was carried out in order to estimate the mean contents of major oxides and ba co cu ni pb rb s sr v zn and zr in different lithological subsets and to identify anomalies related with zn pb carbonate hosted mineralization after a detailed evaluation of different anomaly recognition methods using both real and synthetic data the cut off values used in the exploratory data analysis eda were selected as thresholds a prior classification of the rocks based on chemical mineralogical and petrographical data guarantees appropriate homogeneous with respect to major oxides rock groups during the evaluation of the data a data standardization method was developed and applied to the samples collected from the carranza sector n 330 zinc and pb values for each sample were normalized to the particular threshold and interquartile range of their corresponding rock type these normalized values were plotted in geochemical maps the results reveal the presence of zn up to 0 6 and pb max 1380 ppm anomalies concentrated in carbonate facies mainly in limestones dolostones and dolomitic limestones magnesium rich carbonates host the most significant anomalies in the carranza area the great majority of outliers occur around known zn pb mineral occurrences and are concentrated at the edge of the carbonate platform in some cases fault control of the anomalies is indicated

atmospheric dispersion of natural carbon dioxide emissions on vulcano island italy la fossa quiescent volcano and its surrounding area on the island of vulcano italy are characterized by intensive persistent degassing through both fumaroles and diffuse soil emissions periodic degassing crises occur with marked increase in temperature and steam and gas output mostly co2 from crater fumaroles and in co2 soil diffuse emission from the crater area as well as from the volcano flanks and base the gas hazard of the most inhabited part of the island vulcano porto was investigated by simulating the co2 dispersion in the atmosphere under different wind conditions the disgas dispersion of gas code an eulerian model based on advection diffusion equations was used together with the mass consistent diagnostic wind model numerical simulations were validated by measurements of air co2 concentration inside the village and along the crater s rim by means of a soil co2 automatic station and a tunable diode laser device the results show that in the village of vulcano porto the co2 air concentration is mostly due to local soil degassing while the contribution from the crater gas emission is negligible at the breathing height for humans and always remains well below the lowest indoor co2 concentration threshold recommended by the health authorities 1000 ppm outdoor excess co2 maxima up to 200 ppm above local background co2 air concentration are estimated in the center of the village and up to 100 ppm in other zones however in some ground excavations or in basements the health code threshold can be exceeded in the crater area because of the combined effect of fumaroles and diffuse soil emissions co2 air concentrations can reach 5000 7000 ppm in low wind conditions and pose a health hazard for visitors

compound specific isotopic variability in uinta basin native bitumens paleoenvironmental implications abstract we have analyzed the solvent extracts from three different types of native bitumens from the uinta basin in northeastern utah by a variety of analytical techniques including gc irms to evaluate variations in the paleodepositional environment during two periods of lake uinta deposition the gilsonite and tabbyite bitumens are associated with parachute creek member sediments deposited during a major expansion of ancient lake uinta compound specific isotopic analyses of s carotane and phytane 13 c 32 6 to 32 1 0 from these bitumens reflect input from primary photosynthetic producers such as cyanobacteria sterane 13c values 34 5 to 29 2 0 refflect contributions from lacustrine algae while extremely depleted 13c values for methylhopanes 58 1 to 61 5 0 suggest input from methanotrophic bacteria variations in the 13c values of the hopanes 51 4 to 37 7 0 imply additional input from other bacterial sources the wurtzilite bitumen was generated from the saline facies of the green river formation deposited during a later regression of lake uinta compound specific isotopic analyses of phytane 13 c 30 1 0 and steranes 13 c 29 6 to 26 7 0 from this bitumen indicate continued input from primary producers and eukaryotes the higher relative concentrations of gammacerane 13 c 26 9 0 indicate increasing input from aerobic protozoa we observed a slight enrichment in 13c in the wurtzilite extract and several biomarkers and suggest that this is a result of sulfate reducing bacteria outcompeting methanogens thereby eliminating the influence of methanotrophs in this later saline stage of deposition

multiple hazards and paths to eruptions a review of the volcanic system of vulcano aeolian islands italy abstract vulcano is one of the 7 volcanic islands and 6 seamounts forming the aeolian volcanic district italy vulcano has a long eruptive record and its last eruption 1888 90 originated the definition of the vulcanian eruptive style like most volcanic islands vulcano generates many potentially interconnected hazards determining a potentially high risk here we review the state of knowledge on its geology eruptive activity historical accounts structural setting geophysical and geochemical surveillance and available hazard quantifications in order to have an updated picture of the state knowledge on volcanic hazard we follow a prototypal reviewing scheme based on three standardized steps i review of the volcanic system ii review of available eruptive and non eruptive hazard quantifications iii development of a conceptual interpretative model we find that while a rather vast literature is dedicated to the volcanic system of vulcano and the reconstruction of past events few quantitative hazard assessments exist in addition the range of natural variability considered for each hazard is potentially underestimated e g limited range of considered eruption magnitude and style and of vent position as it is the potential effect of multi hazard impact the developed conceptual model for the feeding system provides a synthetic picture of the present knowledge about the system as emerged from the review in addition it allows for the identification of potential paths to eruption and provides a first order link among the main hazards this review provides an up to date snapshot of existing knowledge on volcanic hazard at vulcano on which to build future hazard quantifications as well as to support present and future decision making

perturbation of the marine nitrogen cycle during the late ordovician glaciation and mass extinction abstract the late ordovician was a critical interval in geologic history during which both the biosphere and marine environments underwent severe perturbations including one of the big five phanerozoic mass extinctions and the massive but short term 0 5 myr hirnantian glaciation the onset and termination of the hirnantian glaciation have been widely accepted as the triggers for the two extinction pulses that comprise the late ordovician biocrisis but the mechanisms that caused the hirnantian glaciation itself remain poorly known here we analyze the nitrogen isotope composition 15 n of two sections in south china wangjiawan and nanbazi in order to better understand nitrogen cycle perturbations in the late ordovician ocean and their relationship to contemporaneous climatic and biogeochemical changes low 15 n 1 in the upper katian and lower rhuddanian of both sections suggests intensive i e near quantitative denitrification and thus nitrogen fixation as the main source of biologically available nitrogen for primary producers a positive 15 n excursion in both sections during the hirnantian indicates weaker i e non quantitative denitrification possibly as a result of more vigorous thermohaline circulation and improved ocean ventilation weaker denitrification would have reduced the flux of n 2 o an intermediate product of denitrification to the atmosphere n 2 o is a potent greenhouse gas and a major decline in its production would have led to cooler climatic conditions and ultimately the hirnantian glaciation a global survey of published nitrogen isotope records suggests that similar processes operated broadly within the late ordovician global ocean

origin of petroleum in the neoproterozoic cambrian south oman salt basin abstract the south oman salt basin sosb is host to the world s oldest known commercial deposits most of the south oman oils have been proven to be associated with the source rocks of the neoproterozoic to cambrian huqf supergroup but the assignment of oils to specific huqf intervals or facies has been hampered by the geochemical similarity of the organic matter across the entire huqf sequence possibly as a consequence of limited change in the local palaeoenvironment and biota over the time of its deposition this study was conducted to establish improved correlations between organic rich rock units and reservoir fluids in the sosb through detailed molecular and isotopic analysis of the huqf supergroup with special emphasis directed towards understanding the ara carbonate stringer play unusual biomarkers tentatively identified as a norsteranes show distinctive patterns among carbonate stringer oils and rocks different from those observed in nafun sediments and ara rocks from the athel basin these putative a norsteranes form the basis for new oil source correlations in the sosb and provide for the first time geochemical evidence of a self charging mechanism for the carbonate stringer play the paucity of markers specific to the nafun group shuram buah and masirah bay formations confounds attempts to quantify their respective contributions to huqf oil accumulations nafun inputs can only be determined on the basis of subtle differences between nafun and ara biomarker ratios the most useful geochemical characteristics delineating nafun group organic matter from ara group intra salt source rocks included low relative abundance of mid chain monomethyl alkanes x compounds low relative abundance of gammacerane 28 30 dinorhopane 25 28 30 trinorhopane and 2 methylhopanes low c 22 t c 21 t and high c 23 t c 24 t cheilanthanes ratio values based on these parameters molecular evidence for major contributions of liquid hydrocarbons from nafun group sediments shuram buah and masirah bay formations is lacking our results suggest that the majority of sosb hydrocarbon accumulations originate from within the ara group either from the carbonate stringers or from the package of sediments that comprises the thuleilat athel silicilyte and u shale formations subtle aspects of the composition of some carbonate stringer and post salt huqf oils could suggest some degree of sourcing from the nafun rocks but stronger evidence is needed to confirm this

time space variation of volcano seismic events at la fossa vulcano aeolian islands italy new insights into seismic sources in a hydrothermal system we investigated the relationship between volcano seismic events recorded at la fossa crater of vulcano aeolian islands italy during 2004 2006 and the dynamics of the hydrothermal system during the period of study three episodes of increasing numbers of volcano seismic events took place at the same time as geothermal and geochemical anomalies were observed these geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids three classes of seismic events long period high frequency and monochromatic events characterised by different spectral content and various similarity of the waveforms have been recognised these events clustered mainly below la fossa crater area at depths of 0 5 1 1 km b s l were space distributed according to the classes based on their features we can infer that such events at vulcano are related to two different source mechanisms 1 fracturing processes of rocks and 2 resonance of cracks or conduits filled with hydrothermal fluid in the light of these source mechanisms the increase in the number of events at the same time as geochemical and geothermal anomalies were observed was interpreted as the result of an increasing magmatic component of the hydrothermal fluids implying an increase of their flux indeed such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids increased pore pressures gave rise to fracturing processes while the increased fluid flux favoured resonance and vibration processes in cracks and conduits finally a gradual temporal variation of the waveform of the hybrid events one of the subclasses of long period events was observed likely caused by heating and drying of the hydrothermal system

first plants cooled the ordovician the late ordovician period ending 444 million years ago was marked by the onset of glaciations the expansion of non vascular land plants accelerated chemical weathering and may have drawn down enough atmospheric carbon dioxide to trigger the growth of ice sheets

transpressive strain on the lipari vulcano volcanic complex and dynamics of the la fossa cone aeolian islands sicily revealed by gps surveys on a dense network abstract ground deformation resulting from the last two gps surveys carried out in march 2006 and september 2007 on the lipari vulcano volcanic complex are analyzed data inversion was performed by genetic algorithms approach using the horizontal strain measured on 258 gps baselines in order to avoid bias due to the ambiguity in fixing the reference system and to disregard the vertical deformation of the la fossa cone there are two networks in this area the main lipari vulcano network and the denser vulcano nord one surveying strategies adopted for the main network during the latest surveys allowed long baselines from lipari and vulcano to the surrounding permanent stations in the southern tyrrhenian to be processed with reliable accuracy the fast static strategy was instead adopted to survey the vulcano nord network data from the main lipari vulcano network has been processed in the itrf05 frame and also in a local reference frame together with the vulcano nord data a significant northward motion of vulcano island with respect to the itrf05 has been detected this motion abruptly decreases in the northern part of vulcano suggesting a decoupling of the main vulcano island from the rest of the volcanic complex the analysis in the local reference frame evidenced a relative sse ward motion of lipari and northern part of vulcano with respect to the central and southern vulcano this comparison also highlights a local uplift of the la fossa cone in addition a strain tensor analysis was performed which highlighted a main nne ssw contraction and a minor ese wnw extension detected only on the southern part of vulcano this results are in agreement with a transpressive kinematics of the lipari vulcano volcanic complex with a main dextral component of displacement along a nw se striking structure

possible late middle ordovician organic carbon isotope excursion evidence from ordovician oils and hydrocarbon source rocks mid continent and east central united states oils generated by middle ordovician rocks are found throughout the mid continent and east central regions of the united states gas chromatographic characteristics of these oils include a relatively high abundance of n alkanes with carbon numbers less than 20 a strong predominance of odd numbered n alkanes between c10 and c20 and relatively small amounts of branched and cyclic alkanes saturated and aromatic hydrocarbon fractions of 43 ordovician oils from the anadarko ardmore forest city illinois michigan salina sedgwick and williston basins and the iowa shelf demonstrate a wide range in carbon isotope composition dgr13csat 24 9 pmil to 33 9 pmil dgr13carom 24 3 pmil to 33 7 pmil saturated and aromatic hydrocarbons extracted from late middle ordovician shales 17 core samples show ranges in dgr13c similar to that of the oils the wide ranges in dgr13c for oils and rock extracts reflect a major positive excursion s 6 9 per pmil in organic matter dgr13c in late middle ordovician rocks this excursion has at least a regional significance in that it can be documented in sections 480 mi 770 km apart in south central kansas and eastern iowa the distance may be as much as 930 mi 1 500 km if the carbon isotope variations observed in michigan basin ordovician oils and in organic matter from late middle ordovician rocks in southwestern ontario are related to the same carbon isotope excursion organic matter dgr13c in core samples from south central kansas and eastern iowa is not directly related to variations in quantity or quality of organic matter or maceral compositi n the positive excursion in organic matter dgr13c is a possible result of increased organic matter productivity and or preservation the parallel shifts in organic and carbonate dgr13c in core samples from 1 e m greene well washington county iowa imply changes in the isotope composition of the ocean atmosphere carbon reservoir differences in the magnitude of the carbon isotope shifts between organic matter 8 8 pmil and carbonate 4 2 pmil in this core suggest a decrease either locally or regionally in available dissolved co2 possibly a result of high organic matter productivity and or limited circulation in the late middle ordovician seas

massive expansion of marine archaea during a mid cretaceous oceanic anoxic event biogeochemical and stable carbon isotopic analysis of black shale sequences deposited during an albian oceanic anoxic event 112 million years ago indicate that up to 80 weight percent of sedimentary organic carbon is derived from marine nonthermophilic archaea the carbon 13 content of archaeal molecular fossils indicates that these archaea were living chemoautotrophically their massive expansion may have been a response to the strong stratification of the ocean during this anoxic event indeed the sedimentary record of archaeal membrane lipids suggests that this anoxic event marks a time in earth history at which certain hyperthermophilic archaea adapted to low temperature environments

molecular indicators of redox and marine photoautotroph composition in the late middle ordovician of iowa u s a abstract saturated and aromatic hydrocarbons were used to evaluate depositional redox conditions and marine photoautotroph contributions to middle caradocian strata of the central united states ia at the base of the spechts ferry member of the decorah formation 13c enriched aryl isoprenoids derivatives of green sulfur bacteria become abundant indicating the development of photic zone anoxia this is coincident with the disappearance of the organic walled microfossil gloeocapsomorpha prisca and a marked decrease in the relative abundances of cyanobacterial biomarkers the development of dysoxic to anoxic conditions and or associated changes in basin circulation potentially affected the distributions and abundances of these organisms in the overlying guttenberg member g prisca derived organic matter becomes dominant but relative cyanobacteria abundances remain low in addition the percentage total organic carbon is greater than 20 even though selected biomarker ratios pristane phytane ratios greater than 3 and homohopane indices less than 0 5 and the presence of bioturbation indicate that bottom waters were oxygenated it is suggested that deposition of g prisca affected both organic matter preservation and depositional redox conditions observed variations in redox indicators and marine photoautotroph contributions are associated with changes in siliciclastic deposition reported macrofauna turnover and with evidence for oceanic cooling and a change in circulation patterns documented in the eastern united states

migrated hydrocarbons in outcrop samples revised petroleum exploration directions in the tarim basin abstract the application of age specific biomarker distributions established from mature exploration areas of the tarim basin northwestern china indicates that most carboniferous permian outcrop samples in the eastern segment of the southwest depression previously believed to have significant petroleum source potential in fact contain migrated hydrocarbons derived from cambrian lower ordovician strata new geochemical results have led to a major revision of petroleum exploration directions in this area

gas hazard assessment in a densely inhabited area of colli albani volcano cava dei selci roma the northwestern flank of the colli albani a quaternary volcanic complex near rome is characterised by high pco2 values and rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil the most significant of these zones is cava dei selci where many houses are located very near to the gas emission site the emitted gas consists mainly of co2 up to 98 vol with an appreciable content of h2s 0 8 2 the he and c isotopic composition indicates as for all fluids associated with the quaternary roman and tuscany volcanic provinces the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates an advective co2 flux of 37 tons day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool present in the rainy season in a topographically low central part of the area a co2 soil flux survey with an accumulation chamber carried out in february march 2000 over a 12 000 m2 surface with 242 measurement points gave a total mostly conductive flux of 61 tons day co2 soil flux values vary by four orders of magnitude over a 160 m distance and by one order of magnitude over several metres a fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations six surveys carried out from may 2000 to june 2001 have shown large variations of the total co2 soil flux 8 25 tons day the strong emission of co2 and h2s which are gases denser than air produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man the gas hazard near the houses has been assessed by continuously monitoring the co2 and h2s concentration in the air at 75 cm from the ground by means of two automatic stations certain environmental parameters wind direction and speed atm p t humidity and rainfall were also continuously recorded at both stations h2s and co2 exceeded by several times the recommended concentration thresholds the highest co2 and h2s values were recorded always with wind speeds less than 1 5 m s mostly in the night hours our results indicate that there is a severe gas hazard for people living near the gas emission site of cava dei selci and appropriate precautionary and prevention measures have been recommended both to residents and local authorities

diffuse emission of co2 from the fossa crater vulcano island italy numerous measurements of co2 degassing from the soil carried out with the accumulation chamber method indicate that in the period april july 1995 the upper part of the fossa cone released a total output of 200 t d 1 of co2 which corresponds to approximately 1000 t d 1 of steam these large amounts of fluids are of the same order of magnitude as those released by the high temperature fumarolic field located inside the crater the spatial distribution of soil gas fluxes shows that the main structures releasing co2 are the inner slopes of the crater and a nw se line located ne of the crater rim which correspond to the main direction of vulcano island active faults the comparison of the co2 maps with the soil temperature distribution derived from both direct measurements and airborne infrared images indicates the occurrence of extensive condensation of fumarolic steam within the upper part of the fossa cone whose total amount is comparable to the rainfall budget part of the condensate which originates from this process contributes to the recharge of the phreatic aquifer of porto plain modifying the chemical and isotopic composition of the groundwater

new evidence for land plants from the lower middle ordovician of saudi arabia macerations of middle ordovician llanvirnian shales from saudi arabia yield an assemblage of spores of probable land plants cryptospores acritarchs and chitinozoa the production of sporopollenin containing sporelike tetrads is considered a fundamental character of the embryophytes because no extant algae produce spores of this type no trilete spores were found at this horizon reinforcing previous assertions that obligate meiotic tetrads predate the earliest trilete spores sporomorph tetrads and dyads in conjunction with cuticlelike fragments were probably derived from terrestrial plants at a bryophyte grade although there are reports of possibly older cryptospores the hanadir assemblage described herein clearly establishes their presence by llanvirnian time

seismic signals in geothermal areas of active volcanism a case study from la fossa vulcano italy since the last eruption 1888 1890 volcanism at vulcano aeolian archipelago southern tyrrhenian sea has taken the form of persistent fumarolic activity the gas vapour phases of the geothermal systems are mainly discharged within two restricted areas about 1 km apart from each other in the northern part of the island these areas are la fossa crater and the beach fumaroles of the baia di levante fluids released at the two main fumarolic fields display quite different chemical and temperature characteristics implying different origins the local seismicity essentially takes the form of discrete shocks of shallow origin depth 1 km at la fossa usually with energy 1013ergs they are thought to be related to the uprise of pressurized hot gases and vapours discharged at the crater fumaroles the present investigation points to the existence of two principal categories of seismic events called m shocks and n shocks these are short events normally 10 s m type shocks are thought to be due to resonance vibrations within the interior of the volcano probably driven by the excitation of shock waves within cavities deeply affected by deposition and alteration of self sealant hydrothermal minerals n type events display features that resemble those of volcano tectonic earthquakes but have no recognizable s phases here they are tentatively attributed to microfracturing of rocks which have been extensively hydrothermally altered results of the present study permit a preliminary conceptual model of the local shallow seismic processes in the framework of geochemical modelling of fumarolic activity and geological inferences from geothermal drilling

an innovative method for continuous measurement of soil co2 flux abstract herein we present a method for continuous measurement of soil co 2 flux that is completely new and distinct from existing instruments the foremost difference is that instead of using an infrared gas analyser irga the new device measures soil co 2 flux by means of a simple pressure sensor measuring pressure transients inside a closed polymeric tube inserted into the soil this allows continuous measurements even in soil placed in environments that could potentially damage irga in addition due to the innovative operating principle measurements of soil co 2 flux can be effortlessly performed also in strongly harsh weather conditions theoretical equations were derived for calculating soil co 2 flux solely using measured transient values the reliability of the equations was rigorously tested with a variety of experiments continuous measurements over four months acquired in a high emission area on the island of vulcano compared favourably with the data obtained using an established method

relocation and focal mechanisms of earthquakes in the south central sector of the aeolian archipelago new structural and volcanological insights abstract to recognize possible spatial clusters and identify active seismogenic zones and structures in the aeolian archipelago in the south of italy we analyzed the spatial pattern of seismicity between 1993 and 2010 in a selected area comprising vulcano lipari salina and filicudi and calculated 22 fault plane solutions fpss for shocks with magnitude greater than 2 7 first we computed a 1 d velocity model for this area including information from recorded earthquakes by a joint hypocenter velocity inversion kissling et al 1994 successively we applied the double difference approach of waldhauser and ellsworth 2000 finding that a certain part of the scattered epicenter locations collapse in roughly linear features relocated seismicity evidenced three main alignments oriented nnw sse and ne sw at different depths that concur well with the known tectonic lineaments and focal mechanisms a detailed discussion is focused on a seismogenetic structure ne sw oriented 3 8 km deep located in the northern area of vulcano island this recognized element could represent a link between magma accumulation zones thus representing a possible preferential pathway along which magma may intrude two earthquake clusters located south west and east of vulcano with their focal mechanisms highlight the aeolian tindari letojanni fault system seismic activity and the existence of a transitional zone going from the n s compressive domain that dominates the aeolian islands to the nw se extensional domain characterizing the south eastern tyrrhenian

testing the tunable diode laser system in extreme environments measuring high and low co2 concentrations in both active volcanic and geothermal settings abstract measuring co2 emissions in geothermal and volcanic areas is sometimes difficult because of large areas to cover and sites often inaccessible measuring high levels of co2 concentration can provide information on hidden structure in geothermal areas and recording changes in co2 concentration on volcanic areas can help monitor the level of volcanic activity the purpose of this study was to use the tunable laser diode tdl absorption spectroscopy method to test levels of co2 concentrations at two extreme environments white island volcano the most active volcano of new zealand with large and concentrated gas fluxes and ngapouri geothermal area a small geothermal area in the taupo volcanic zone new zealand with relatively low and diffuse gas emissions in 2017 for the first time using tdl at white island co2 concentration measurements performed across the active fumarole fields had the highest co2 concentrations of 657 ppm tdl survey measurements were also conducted across fault strands near the ngapouri geothermal area and the results complemented co2 flux results obtained with the accumulation chamber method higher co2 concentrations were measured close to the mapped ngapouri splays with a maximum of 484 ppm the maximum co2 flux measured in the same area was 100 g m 2 day 1 however the highest co2 fluxes measured along the transects and by the mapped faults were less clear but the co2 concentrations increased closer to the fault splays advantages and disadvantages of using a tdl system have been described and compared to the accumulation chamber method the results from the tdl system demonstrated that co2 concentrations can be used as a tool with other geophysical tools for both detecting and highlighting geological structures where no obvious thermal activity is present and for monitoring purposes on active volcanoes

local and global perspectives on carbon and nitrogen cycling during the hirnantian glaciation abstract the impact of climate and ocean circulation changes on marine carbon and nitrogen cycling was investigated for a period covering the late ordovician hirnantian glaciation three sections were studied two from nevada one proximal and one distal and one from the yukon the opportunity to compare 13 c carb 13 c org and 13 c grap profiles between ocean and epeiric platform settings enabled a more thorough assessment of environmental and diagenetic factors influencing the preservation of seawater 13 c values at each stratigraphic section using the best preserved sedimentary components from the two nevada sections a lowstand sedimentary gradient of 4 was found between platform and ocean settings during the hirnantian glaciation gradients of similar magnitude have been reported from hirnantian platforms in the canadian arctic and baltic basins taking the outboard sections as the most representative of the ocean carbon pool a mean positive 13 c shift of just 2 7 0 4 is calculated which is significantly smaller than the 5 7 positive shifts recorded in epeiric platform settings the discrepancy is attributed to the effects of local carbon cycling in tropical and subtropical epeiric seas it is hypothesized that increased carbonate weathering caused 13 c values of local carbon weathering fluxes to increase which in turn caused seawater 13 c values to increase in basin proximal settings in addition nutrient dust fluxes may have contributed to increased levels of photosynthetic activity in proximal settings driving sedimentary 13 c values even higher much higher than sediment deposited in outboard settings where carbon exchanges with the surface ocean were less restrictive a 15 n profile reconstructed from deposits of the distal vinini creek section records a 1 5 positive shift through the hirnantian glacial interval interpreted as a major late ordovician upwelling zone high organic carbon 1 wt and high hydrogen indices 400 600 make the vinini creek section a suitable candidate for the preservation of original sedimentary 15 n records to explain the results a conceptual model of ocean nitrogen cycling under greenhouse climate conditions is presented that highlights the role of cyanobacteria as both primary producers and nitrogen fixers it is hypothesized that in greenhouse climates the fixed nitrogen inventory of the abyssal ocean was low due to efficient denitrification in the ocean s expansive oxygen minimum zones this caused algal productivity to become strongly dependent on continuous supplies of fixed nitrogen from cyanobacteria in the photic zone yielding sedimentary 15 n values between 0 and 2 by contrast the cooler icehouse climate of the hirnantian led to increased ocean ventilation greater partitioning of atmospheric oxygen into downwelling surface waters and oxygen minimum zone shrinkage as a result fixed nitrogen levels climbed in the ocean s abyssal depths due to the lower denitrification rates this in turn allowed nitrogen with high 15 n values to recycle back into the photic zone driving sedimentary 15 n values higher during the hirnantian glaciation

diffuse co2 soil degassing and co2 and h2s concentrations in air and related hazards at vulcano island aeolian arc italy ingv dpc programme project v5 diffuse degassing in italy airplane firb project of the italian ministry of the university and research

spatial domain analysis of carbon dioxide from soils on vulcano island implications for co2 output evaluation abstract the carbon dioxide emissions of volcanoes have been targeted as effective contributors of co 2 to the atmosphere however different sources can be effective and active at the same time in the generation and release of co 2 in volcanic zones since isotopic fingerprinting of co 2 allows the precise identification of different sources coupling carbon isotope and co 2 flux measurements enables the evaluation of the mass contribution of each source to the carbon dioxide emissions this paper accounts for the first extensive spatial analysis of coupled measurements of carbon isotopologues of co 2 in the soil gases and co 2 fluxes discharged by soils on vulcano island an innovative method has been designed tested and fine tuned in the laboratory to measure 13 c co 2 values directly in field using a new type of laser based isotopologues analyzer namely a deltaray thermo fisher scientific the method can be used to determine the carbon isotope composition across the full range of co 2 concentrations in the soil gases 0 100 vol these data have been combined with measurements of the co 2 contents in the soil gases to distinguish co 2 from deep origins from co 2 of biogenic origin in the inhabited area of vulcano porto the method of evaluating the amount of deep origin co 2 in the soil gases is widely applicable in volcanic and geothermal zones for evaluation and monitoring purposes for both gas and volcanic hazards

organic geochemical characteristics of black shales across the ordovician silurian boundary in the holy cross mountains central poland abstract black shales in the holy cross mountains area of poland provide a record of environmental change across the ordovician silurian boundary the changing depositional conditions have generated a variation in organic matter contents above and below the boundary investigating the organic constitution of these black shales has the potential to reveal how their organic matter contents were generated and how suitable these rocks and their lateral equivalents may be for exploitation as shale gas reservoirs one outcrop at the holy cross mountains with a continuous section across the ordovician silurian boundary occurs near the village of bardo stawy in the kielce region and contains sandy silty mudstones as well as grey and black shales organic geochemical analyses of samples at bardo stawy reveals low total organic carbon toc contents for ordovician samples and higher toc values for silurian samples organic biomarkers indicate that the ordovician rocks were deposited in a shallow marine shelf setting while the silurian rocks were deposited in a deeper marine environment the progressive increase in toc from the uppermost ordovician to the lowermost silurian rocks reflects increasingly oxygen poor depositional conditions during the post glacial transgression following the deposition and preservation of organic matter in the ordovician and silurian rocks these rocks were buried and subjected to thermal maturation rock eval and biomarker thermal maturity parameters all indicate that the organic matter is mature and lies within the oil window the ordovician and silurian shales have direct relevance to recent attempts to discover and exploit shale gas reservoirs in poland our data and interpretations suggest that the relatively low toc values

molecular isotopic evidence of environmental and ecological changes across the cenomanian turonian boundary in the levant platform of central jordan abstract we evaluated the structure of planktonic communities and paleoenvironmental conditions throughout the cenomanian turonian oceanic anoxic event oae2 by studying bulk geochemical properties and the molecular isotopic composition of source specific hydrocarbons from organic rich sediments deposited in an intrashelf basin at the levant platform central jordan high concentrations of desmethyl and 4 methylsteranes as well as dinosteranes indicate that marine algae including dinoflagellates were the main primary producing organisms the presence of 2 methylhopanes and 13 c enriched hopanes in addition to isotopically enriched aryl isoprenoids evidenced the contribution of cyanobacteria and green sulfur bacteria respectively additionally variable but fairly low 15 n values during oae2 suggest the occurrence of diazotrophy as a likely important process fueling primary production during oae2 in this stratified anoxic continental platform variations in the relative contribution of biomarkers revealed changes in planktonic communities associated with sea level change and water column stratification oae2 was characterized by strong stratification anoxic bottom waters and a deep chemocline as evidenced by high gammacerane and homohopane indices and the absence of photic zone euxinia pze markers respectively however the presence of isorenieratane and its derivatives in post oae black shales points to a shoaling of the chemocline and to pze this interval was also characterized by an exceptionally high abundance of chlorophyll derived pristane and phytane up to 2 mg g 1 toc likely as a result of highly enhanced primary production and organic matter preservation remarkably this high productivity event co occurs with an exceptionally high abundance of calcispheres reported elsewhere to be part of a global bio event

hazardous gas emissions from the flanks of the quiescent colli albani volcano rome italy abstract gas hazard was evaluated in the three most important cold gas emission zones on the flanks of the quiescent colli albani volcano these zones are located above structural highs of the buried carbonate basement which represents the main regional aquifer and the main reservoir for gas rising from depth all extensional faults affecting the limestone reservoir represent leaking pathways along which gas rises to the surface and locally accumulates in shallow permeable horizons forming pressurized pockets that may produce gas blowout when reached by wells the gas mainly composed of co 2 90 vol contains appreciable quantities of h 2 s 0 35 6 vol and both represent a potentially high local hazard both gases are denser than air and accumulate near ground where they may reach hazardous concentrations and lethal accidents frequently occur to animals watering at local ponds in order to evaluate the rate of degassing and the related hazard co 2 and h 2 s diffuse soil flux surveys have been repeatedly carried out using an accumulation chamber the viscous gas flux of some important discrete emissions has been evaluated and the co 2 and h 2 s air concentration measured by portable devices and by tunable diode laser profiles the minimum potential lethal concentration of the two gases 250 ppm for h 2 s and 8 vol for co 2 is 320 times higher for co 2 whereas the co 2 h 2 s concentration ratio in the emitted natural gas is significantly lower 15 159 this explains why h 2 s reaches hazardous even lethal concentrations more frequently than co 2 a relevant hazard exists for both gases in the depressed zones channels excavations particularly in the non windy early hours of the day

association of orogenic activity with the ordovician radiation of marine life the ordovician radiation of marine life was among the most substantial pulses of diversification in earth history and coincided in time with a major increase in the global level of orogenic activity to investigate a possible causal link between these two patterns the geographic distributions of 6576 individual appearances of ordovician vician genera around the world were evaluated with respect to their proximity to probable centers of orogeny foreland basins results indicate that these genera which belonged to an array of higher taxa that diversified in the middle and late ordovician trilobites brachiopods bivalves gastropods monoplacophorans were far more diverse in and adjacent to foreland basins than they were in areas farther removed from orogenic activity carbonate platforms this suggests an association of orogeny with diversification at that time

carbon isotopes support the presence of extensive land floras pre dating the origin of vascular plants abstract multiple lines of evidence indicate that earth s land masses became green some 2 7 ga ago about 1 billion years after the advent of life about 2 2 billion years later land plants abruptly appear in the fossil record and diversify marking the onset of ecologically complex terrestrial communities that persist to the present day given this long history of land colonization surprisingly few studies report direct fossil evidence of emergent vegetation prior to the continuous record of life on land that starts in the mid silurian ca 420 425 ma ago here we compare stable carbon isotope signatures of fossils from seven ordovician silurian 450 420 ma old appalachian biotas with signatures of coeval marine organic matter and with stable carbon isotope values predicted for ordovician and silurian liverworts bryocarb model the comparisons support a terrestrial origin for fossils in six of the biotas analyzed and indicate that some of the fossils represent bryophyte grade plants our results demonstrate that extensive land floras pre dated the advent of vascular plants by at least 25 ma the appalachian fossils represent the oldest direct evidence of widespread colonization of continents these findings provide a new search image for macrofossil assemblages that contain the earliest stages of land plant evolution we anticipate they will fuel renewed efforts to search for direct fossil evidence to track the origin of land plants and eukaryotic life on continents further back in geologic time

backarc thrust faulting and tectonic uplift along the caribbean sea coast during the april 22 1991 costa rica earthquake surface deformation and a tsunami accompanied the destructive april 22 1991 costa rica panama earthquake ms 7 5 along a 135 km stretch of caribbean coast coseismic uplift was measured between the lower and upper limits of sessile intertidal organisms stranded on coral reefs the preearthquake and postearthquake high tide levels located from driftwood lines on beaches and the preearthquake and postearthquake tide levels as pointed out by local residents the nature and distribution of offshore vertical displacements were further constrained from analysis of measured run up heights and reported arrival times of the tsunami uplift detected along the coast jumped within 4 km from zero to 157 cm near limon and generally decreased over a distance of 70 km southward to the border with panama these data map an axis of uplift that intersects the coastal beach ridge just north of the port of moin and runs offshore to the east and south roughly parallel to the coast no surface faulting was found the earthquake and tsunami were generated by backarc thrusting along faults that bound the north panama deformed belt and dip from the caribbean sea beneath costa rica and northern panama combined geodetic and seismological data indicate that the main rupture dips landward at an angle of about 30 and is approximately 40 km wide and 80 km long dislocation models suggest 2 2 m of slip on a causative thrust fault striking between 105 and 120 we estimate that the repeat time for this type of earthquake is 200 to 1100 years the historical record and new isotopic data favor the middle of the range

relationships between diffuse co2 emissions and volcanic activity on the island of vulcano aeolian islands italy during the period 1984 1994 measurements of co2 flux from the ground were periodically carried out on the island of vulcano aeolian islands italy between 1984 and 1994 three high flux areas were identified at the foot of the volcanic cone la fossa either inside or very close to the main village effect of the choice of the sampling grid was evaluated a different sampling grid resulted in similar distribution patterns but with different co2 fluxes therefore the absolute estimate of the total flux from the investigated area includes a large degree of uncertainty but repeated measurements with permanent sampling sites are accurate and can detect small changes no correlation of the flux with atmospheric parameters was found at sites with high fluxes some periods characterized by high co2 fluxes were observed and a close correlation was found between the gas emissions from the ground and other geochemical and geophysical parameters such as temperature chemical composition steam and so2 flux from fumaroles seismic energy release and ground deformations the results show that major temporal variations of diffuse co2 flux are related to variations in volcanic activity

lipid taphonomy in the proterozoic and the effect of microbial mats on biomarker preservation the pre ediacaran biomarker record has several characteristic features that distinguish it from its phanerozoic counterpart including high concentrations of unresolved complex mixture ucm low concentrations or absence of eukaryotic steranes and a conspicuous carbon isotopic enrichment of n alkyl lipids relative to bulk sedimentary carbon we propose that these derive from a common non actualistic taphonomy based on the pervasive presence of microbial mats prior to the cambrian substrate revolution such mats would have formed a significant mechanical and biochemical barrier to in falling plankton leaving a biomarker record dominated by benthic microbial lipids most of which would have originated from the lower heterotrophically reworked layers of the mat most proterozoic biomarker assemblages studied in this work derive from shallow water sediments where cyanobacteria dominated upper mats represent a focused source of corrosive molecular oxygen this mat seal effect was broken with the onset of bioturbation in the ediacaran and early cambrian at which point the primary source of fossil biomarkers switched from the benthos to the plankton

biomarkers of black shales formed by microbial mats late mesoproterozoic 1 1 ga taoudeni basin mauritania a b s t r a c t hydrocarbon biomarkers in late mesoproterozoic black shales from the taoudeni basin mauritania northwestern africa were analysed for palaeoenvironmental reconstruction within the atar group touirist formation shales showed the highest content of organic carbon 20 at very low maturity rc less than 0 6 microfacies and biomarker data indicate a shallow marine high productivity low oxygen setting with benthic mats as key players for the accumulation of organic matter both high c s ratios and the occurrence of rearranged hopanes indicate that euxinic conditions were not prevalent likely reflecting the shallow depositional environment steranes were not observed indicating only a minor importance of modern eukaryotic algae although low in abundance a palynological survey however reveals the presence of simple ornamented acritarchs input of highly aromatic biopolymers typical of mesoproterozoic acritarchs or microbial exopolymeric substances may be the origin of an unusually high aromaticity observed for the biomarker extracts high amounts of hopanes suggest that the benthic mats were dominated by cyano bacteria furthermore the presence of 2 3 6 trimethyl aryl isoprenoids points at contributions of organic matter from anoxygenic phototrophic bacteria however low concentrations of these compounds argue against major photic zone anoxia in the overlying water column and rather suggest a role of anoxygenic phototrophs as part of the benthic microbial mat community the high abundances of hopanes in these samples suggest that nitrogen limited conditions may have been common in the taoudeni basin at 1 1 ga these results are consistent with ideas of widespread nitrogen deficiency that emerged in mesoproterozoic oceans due to high denitrification rates in anoxic deep waters cyano and other phototrophic bacteria as well as a limited number of acritarch species were able to cope with such conditions much better than modern algae with their higher nitrogen and trace metal demands 2011 elsevier b v all rights reserved

organic geochemistry of the early toarcian oceanic anoxic event in hawsker bottoms yorkshire england a comprehensive organic geochemical investigation of the hawsker bottoms outcrop section in yorkshire england has provided new insights about environmental conditions leading into and during the toarcian oceanic anoxic event t oae 183 ma rock eval and molecular analyses demonstrate that the section is uniformly within the early oil window hydrogen index hi organic petrography polycyclic aromatic hydrocarbon pah distributions and tricyclic terpane ratios mark a shift to a lower relative abundance of terrigenous organic matter supplied to the sampling locality during the onset of the t oae and across a lithological transition unlike other ancient intervals of anoxia and extinction biomarker indices of planktonic community structure do not display major changes or anomalous values depositional environment and redox indicators support a shift towards more reducing conditions in the sediment porewaters and the development of a seasonally stratified water column during the t oae in addition to carotenoid biomarkers for green sulfur bacteria gsb we report the first occurrence of okenane a marker of purple sulfur bacteria psb in marine samples younger than 1 64 ga based on modern observations a planktonic source of okenane s precursor okenone would require extremely shallow photic zone euxinia pze and a highly restricted depositional environment however due to coastal vertical mixing the lack of planktonic okenone production in modern marine sulfidic environments and building evidence of okenone production in mat dwelling chromatiaceae we propose a sedimentary source of okenone as an alternative lastly we report the first parallel compound specific c13 record in marine and terrestrial derived biomarkers across the t oae the c13 records of short chain n alkanes acyclic isoprenoids and long chain n alkanes all encode negative carbon isotope excursions cies and together they support an injection of isotopically light carbon that impacted both the atmospheric and marine carbon reservoirs to date molecular c13 records of the t oae display a negative cie that is smaller in magnitude compared to the bulk organic c13 excursion although multiple mechanisms could explain this observation our molecular petrographic and rock eval data suggest that variable mixing of terrigenous and marine organic matter is an important factor affecting the bulk organic c13 records of the t oae

deep co2 release revealed by stable isotope and diffuse degassing surveys at vulcano aeolian islands in 2015 2018 abstract the partitioning of carbon dioxide co2 released by soils at vulcano island aeolian islands italy was performed by combining the co2 flux and the carbon isotope measurements based on this method the amount of co2 of volcanic origin was quantified six times during the period 2015 2018 the data analysis allowed us to establish the correlation between co2 soil degassing and changes in the contribution of volcanic fluids carbon isotope determinations were performed in situ to enhance the coverage of data collection in space and time these data were combined with both the co2 contents in the ground gases and the soil co2 flux the amount of volcanic co2 was distinguished from that of biogenic origin by implementing a three component mixing model the results of this study indicate that the increase in co2 output in september 2018 reflects the increase in volcanic gas emissions the measurement method and analysis presented in this work are sufficiently general to be applicable to the monitoring programs of active volcanoes

hydrothermal fluid flow disruptions evidenced by subsurface changes in heat transfer modality the la fossa cone of vulcano italy case study detecting volcanic unrest is of primary importance for eruption forecasting especially on volcanoes characterized by highly dangerous and often seemingly unpredictable phreatic or phreatomagmatic eruptions we present a simple and innovative analysis of shallow vertical temperature profiles to depths of 70 cm these data were recorded at la fossa cone of vulcano aeolian islands italy during an episode of increased hydrothermal and seismic activities that occurred between september and december 2009 this work involves the use of the coefficient of determination r 2 on vertical temperature profiles in order to identify changes in conductive versus convec tive heat transfer modality the increase in convective heat transfer can be related to the disruption of the hydrothermal system due to its pressurization and or variation of ground permeability between the hydrothermal system and the surface while raw temperature data do not evidence any significant variation during the period investigated and the classic temperature gradient is highly influenced by seasonal variations the fluctuation of r 2 displayed striking spikes that coincided with the seismic swarm inside the volcanic edifice such a low cost device associated with easy real time data processing could constitute a very promising yet deceptively simple technique to monitor hydrothermal systems in order to assess the hazard posed by high energy eruptions for populations living close to active volcanoes

biogeochemical evidence for euxinic oceans and ecological disturbance presaging the end permian mass extinction event article i nfo the permian triassic boundary event at 252 2 ma marks the largest extinction of marine fauna in the phanerozoic and there is a wide consensus that the extinction coincided with an intense oceanic anoxic event thestratotypeofthechanghsingianstage preciselyconstrainedbytheptbglobalstratotypesectionandpoint gssp and the gssp for the wuchiapingian changhsingian boundary both at meishan in southern china is well documented in respect to geochronology and the pattern of extinction here we report secular trends in bulk isotopic parameters and lipid biomarkers in a core spanning 214 m of stratigraphic section across the ptb and through the entire changhsingian interval our analysis of these data viewed in the context of relative sea level change and strontium isotopes reveals distinct shifts in paleoenvironmental conditions and profound changes in plankton ecology well before and following the biological extinction event specifically patterns of steroids and triterpenoids indicate a marine plankton community that was heavily dominated by bacteria during the late wuchiapingian middle changhsingian and early griesbachian stages secular trends in aromatic hydrocarbons diagnostic for anoxygenic green sulphur bacteria chlorobiaceae identify periods when euxinic conditions extended into the photic zone during the entire changhsingian stage here also the 15

organic and inorganic geochemistry of low temperature gas discharges at the baia di levante beach vulcano island italy abstract discharge from subaereal and submarine gas vents of the baia di levante beach gases from the vulcano island were sampled for major and trace gas components in may and november 1995 chemical compositions and equilibrium calculations suggest three different groups of co 2 rich gas emissions depending on their distance from the la fossa crater 1 gas vents close to the faraglione area are characterised by high h 2 s contents high calculated equilibrium temperatures based on inorganic species and relatively high proportion of alkene compounds 2 gas vents close to vulcanello are characterised by low calculated equilibrium temperatures and low amounts of alkenes and 3 pontile sample has the highest equilibrium co 2 pressure up to 68 bars which may account for the observed absence of benzene the relative large variability of h 2 s in the baia di levante beach gas discharge may be attributed to either different interactions between iron sulphides and weakly acid waters or catalytic effect of elemental sulphur on the de hydrogenation of cyclo hexane thermodynamic calculations suggest that the main inorganic species and ch 4 may have re equilibrated at relatively shallow depth 10 200 m b s l and 30 600 m b s l for a lithostatic and hydrostatic pressure respectively the slow kinetics of reactions in the c n h 2 n c n h 2 n 2 systems with respect to that of ch 4 co co 2 may explain the observed propene propane ratios which can only be reached at reaction temperatures of 300 350 c this low speed of reactions can also explain the observed disequilibrium of c1 c4 alkanes