a numerical simulation technique to study fault activation characteristics during mining between fault bundles faults especially fault bundles elevate the difficulties of predicting preventing and controlling water inrush during coal seam mining this paper takes the no 163 mining area at jiangzhuang coal mine of shandong province china as a case study a series of faults form structural patterns consisting of the graben horst and fault terrace in the study area the key technical challenge lies in fault activation which affects sizing of economic and safe coal pillar around the fault bundles an innovative numerical simulation technique was applied to understand the movement law of coal seam roof and floor and fault activation among the fault bundles under different mining plans the results show that reasonable arrangement of mining sequence in the working faces is an effective method to reduce the influence from faults in addition coal seam roof and floor damage and faults activation are different during mining under the graben horst and fault terrace settings moreover the horizontal and vertical displacement values of each point on fault plane of hanging wall and footwall indicate that the maximum displacement is related to roof water conducting fractured zone and floor damage zone which increase the probability of fault activation based on the research results a reasonable coal pillar width was designed beside the fault bundle in the no 16301 working face of the no 163 mining area and the mining was completed safely with significant economic benefits for jiangzhuang coal mine

depletion control and analysis for groundwater protection and sustainability in the xingtai region of china excessive groundwater withdrawal from the ordovician karstified limestone aquifer near the city of xingtai in china has created many cones of depression in piezometric levels of the groundwater 100 m of drawdown potentially affecting groundwater dependent environments and threatening urban water supplies groundwater investigations and numerical modeling were undertaken to determine the factors that have caused groundwater depletion in the region so that groundwater protection measures could be developed and implemented these investigations found the major cause of groundwater depletion was water drainage from iron ore mines in the region which had the largest effect on piezometric levels in the aquifer based on the integrated study comprehensive methods of controlling depletion are proposed and tested successfully for groundwater protection in the region these methods mainly include outcrop recharging the aquifer optimization in usage and allocation of water resources regionally the use of curtain grouting in iron ore mines to reduce drainage of the aquifer and drainage control in mining operations applying these methods piezometric levels in the aquifer have increased by more than 30 m and previously dry springs are now flowing on a seasonal basis

impacts of karst paleo sinkholes on mining and environment in northern china the karst paleo sinkhole is a special geological structure widely found in the coal measures of northern china some paleo sinkholes have high permeability and connectivity making them excellent connectors between the karst aquifer and the coal seam consequently during coal extraction disastrous water inrushes take place frequently which cause severe loss not only in mine submersions and personnel casualties but also in environmental quality locations and the geological and hydrogeological characteristics of paleo sinkholes in northern china are presented in situ drilling and excavation results show that paleo sinkholes have different hydrogeological behaviors in different regions and in different mines based on observed data mining induced strata failure in the seam floor is analyzed the existence of paleo sinkholes increases the floor strata failure zone numerical simulation then is adopted to model coal mining with the effects of both the paleo sinkholes and the water pressure in the confined aquifer analyses of the simulation conclude that the paleo sinkhole induces the increase in the strata failure and deformation these make water inrushes more likely to happen

accretion of a new england u s a salt marsh in response to inlet migration storms and sea level rise sediment accumulation rates were determined at several sites throughout nauset marsh massachusetts u s a a back barrier lagoonal system using feldspar marker horizons to evaluate short term rates 1 to 2 year scales and radiometric techniques to estimate rates over longer time scales 137cs 210pb 14c the barrier spit fronting thespartina dominated study site has a complex geomorphic history of inlet migration and overwash events this study evaluates sediment accumulation rates in relation to inlet migration storm events and sea level rise the marker horizon technique displayed strong temporal and spatial variability in response to storm events and proximity to the inlet sediment accumulation rates of up to 24 mm year 1were recorded in the immediate vicinity of the inlet during a period that included several major coastal storms while feldspar sites remote from the inlet had substantially lower rates trace accumulation to 2 2 mm year 1 during storm free periods accumulation rates did not exceed 6 7 mm year 1 but remained quite variable among sites based on137cs 3 8 to 4 5 mm year 1 and210pb 2 6 to 4 2 mm year 1 radiometric techniques integrating sediment accumulation over decadal time scales the marsh appeared to be keeping pace with the relative rate of sea level rise from 1921 to 1993 of 2 4 mm year 1 at one site the210pb based sedimentation rate and rate of relative sea level rise were nearly similar and peat rhizome analysis revealed thatdistichlis spicatarecently replaced this onces patenssite suggesting that this portion of nauset marsh may be getting wetter thus representing an initial response to wetland submergence horizon markers are useful in evaluating the role of short term events such as storms or inlet migration influencing marsh sedimentation processes however sampling methods that integrate marsh sedimentation over decadal time scales are preferable when evaluating a systems response to sea level rise

in situ dynamic monitoring of stress revolution with time and space under coal seam floor during longwall mining in situ dynamic monitoring was used to obtain spatial and temporal strain and stress data in the floor strata during longwall mining at the no 1604 working face in nantun coal mine china the results reveal the presence of four stress stages distributed at four sections along the mining direction weak response stage significant increase stage dramatic decrease stage and slow restoration stage three vertical structural zones are identified under the excavation floor 1 fracture zone 2 deformation zone and 3 lightly affected zone based on detailed analysis of the collected data the relationship between the maximum vertical stress increment and depth is inversely exponential whereas the relationship between the maximum horizontal stress increment and depth is linear the monitoring results are conducive to determining the maximum depth of fracture zone under the coal seam floor and width of the significant stress increase stage which are important factors in controlling groundwater inrush in operating coal mines

lime mud layers in high energy tidal channels a record of hurricane deposition during or immediately following the transit of hurricane andrew august 23 24 1992 across the northern part of the great bahama bank thin laminated beds of carbonate mud were deposited in high energy subtidal channels 4 m depth through the ooid shoals of south cat cay and joulters cays during our reconnaissance seven weeks later we observed lime mud beds exposed in the troughs of submarine oolite dunes and ripples the mud layers were underlain and locally covered by ooid sand the mud beds were lenticular and up to 5 cm thick their bases cast the underlying rippled surface the layers were composed of soft silt and sand sized pellets and peloids and in some areas contained freshly preserved thalassia blades and other organic debris along planes of lamination the beds had a gelatinous consistency and locally had been penetrated by burrowers and plants layers of lime mud had also settled on bioturbated plant stabilized flats and in lagoonal settings but were quickly reworked and made unrecognizable by the burrowing of organisms thicker more cohesive and therefore older mud beds and angular mud fragments associated with ooids from joulters cays have similar characteristics but lack fresh plant fragments we infer that these older beds were similarly deposited and thus record the passage of previous hurricanes or tropical storms storm layers are preserved within channel sediments because migrating ooids prevent attack by the burrowing activity off organisms

high pressure methane and carbon dioxide sorption on coal and shale samples from the parana basin brazil abstract an experimental study has been conducted to assess the potential for coalbed methane production and carbon dioxide storage in coals carbonaceous shales and source rocks in the parana basin in brazil high pressure sorption tests with methane and carbon dioxide were performed on coal and carbonaceous shales from the santa terezinha coalfield and samples from two principal petroleum source rocks measured excess sorption capacities ranged from 0 03 to 0 47 mmol g for methane and 0 14 to 0 81 mmol g for carbon dioxide showing a decrease with decreasing organic matter content linear regression lines for methane sorption capacity vs toc extrapolated to approximately zero whereas for carbon dioxide the intercept of the regression line indicated a residual sorption capacity of 0 2 mmol g on the mineral matter present day gas contents of coals collected from the first cbm well in the santa terezinha coalfield correspond to 13 38 of the measured maximum sorption capacities carbon dioxide sorption capacities exceed methane sorption capacities by a factor of 1 9 to 6 9 for these coals free sorption capacities of the under saturated coals in combination with preferential sorption of carbon dioxide could favour co 2 enhanced methane recovery and co 2 storage in coals and shales of the study area based upon the calculated coal reserves gas contents and measured sorption capacities a total storage potential of 15 4 gt co 2 was estimated for an area of 20 40 km 2 in the santa terezinha coal field assuming a combined co 2 enhanced coalbed methane ecbm production and co 2 storage operation to fully evaluate the potential for carbon dioxide storage and coalbed methane production further studies are required to assess producibility of methane and efficiency of long term co 2 storage in the study area

mechanical behavior of groundwater seepage in karst collapse pillars abstract groundwater inrush has an impartible relationship with geological structures such as karst collapse pillars kcps which are widely distributed in north china in order to study the mechanism of groundwater inrush from coal seam floor the variable mass dynamics and nonlinear dynamics were introduced a mechanical model plug model is established to describe the behavior of water seepage flow in coal seam floor containing kcp the study shows that 1 if the mass of the kcp keeps steady the water seepage velocity in the kcp and the surrounding rocks will reach a constant value soon 2 if the mass of the kcp and the surrounding rocks increases by grouting etc the seepage velocity in the kcp and the surrounding rocks will reach its minimum value gradually and 3 if the mass of the kcp and the surrounding rocks decreases by scouring the flow velocity in the kcp and the surrounding rocks shows a monotone increase the water flow may change into pipe flow especially when a large number of the mass of the kcp and the surrounding rocks enters into goaf road which may lead to instable flow and cause groundwater inrush

bioassay for estimating the biogenic methane generating potential of coal samples abstract generation of secondary biogenic methane in coal beds is likely controlled by a combination of factors such as the bioavailability of coal carbon the presence of a microbial community to convert coal carbon to methane and an environment supporting microbial growth and methanogenesis a set of treatments and controls was developed to bioassay the bioavailability of coal for conversion to methane under defined laboratory conditions treatments included adding a well characterized consortium of bacteria and methanogens enriched from modern wetland sediments and providing conditions to support endemic microbial activity the contribution of desorbed methane in the bioassays was determined in treatments with bromoethane sulfonic acid an inhibitor of microbial methanogenesis the bioassay compared 16 subbituminous coal samples collected from beds in texas tx wyoming wy and alaska ak and two bituminous coal samples from pennsylvania pa new biogenic methane was observed in several samples of subbituminous coal with the microbial consortium added but endemic activity was less commonly observed the highest methane generation 80 mol methane g coal 56 scf ton or 1 75 cm 3 g was from a south tx coal sample that was collected from a non gas producing well subbituminous coals from the powder river basin wy and north slope borough ak contained more sorbed original methane than the tx coal sample and generated 0 23 mol g up to 16 scf ton or 0 5 cm 3 g new biogenic methane in the bioassay standard indicators of thermal maturity such as burial depth nitrogen content and calorific value did not explain differences in biogenic methane among subbituminous coal samples no original methane was observed in two bituminous samples from pa nor was any new methane generated in bioassays of these samples the bioassay offers a new tool for assessing the potential of coal for biogenic methane generation and provides a platform for studying the mechanisms involved in this economically important activity

the importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs abstract the effect of shale composition and fabric upon pore structure and ch 4 sorption is investigated for potential shale gas reservoirs in the western canadian sedimentary basin wcsb devonian mississippian d m and jurassic shales have complex heterogeneous pore volume distributions as identified by low pressure co 2 and n 2 sorption and high pressure hg porosimetry thermally mature d m shales 1 6 2 5 vro have dubinin radushkevich d r co 2 micropore volumes ranging between 0 3 and 1 2 cc 100 g and n 2 bet surface areas of 5 31 m 2 g jurassic shales which are invariably of lower thermal maturity ranging from 0 9 to 1 3 vro than d m shales have smaller d r co 2 micropore volumes and n 2 bet surface areas typically in the range of 0 23 0 63 cc 100 g co 2 and 1 9 m 2 g n 2 high pressure ch 4 isotherms on dried and moisture equilibrated shales show a general increase of gas sorption with total organic carbon toc content methane sorption in d m shales increases with increasing toc and micropore volume indicating that microporosity associated with the organic fraction is a primary control upon ch 4 sorption sorption capacities for jurassic shales however can be in part unrelated to micropore volume the large sorbed gas capacities of organic rich jurassic shales independent of surface area imply a portion of ch 4 is stored by solution in matrix bituminite solute ch 4 is not an important contributor to gas storage in d m shales structural transformation of d m organic matter has occurred during thermal diagenesis creating and or opening up microporosity onto which gas can sorb as such d m shales sorb more ch 4 per weight percent wt toc than jurassic shales inorganic material influences modal pore size total porosity and sorption characteristics of shales clay minerals are capable of sorbing gas to their internal structure the amount of which is dependent on clay type illite and montmorillonite have co 2 micropore volumes of 0 78 and 0 79 cc 100 g n 2 bet surface areas of 25 and 30 m 2 g and sorb 2 9 and 2 1 cc g of ch 4 respectively dry basis a reflection of microporosity between irregular surfaces of clay platelets and possibly related to the size of the clay crystals themselves mercury porosimetry analyses show that total porosities are larger in clay rich shales compared to silica rich shales due to open porosity associated with the aluminosilicate fraction clay rich sediments low si al ratios have unimodal pore size distributions

sensitivity analysis of drilling parameters in rock rotary drilling process based on orthogonal test method abstract drilling exploration is the main method for geological studies of rocks and soil selecting reasonable drilling parameters is important for ensuring the safety and economic benefits of a project according to the force limit equilibrium of rock during rotary drilling and using the energy equilibrium method the relationship between the vertical drilling efficiency and drilling parameters such as the speed of rotation thrust force and rotation torque were deduced in this study through improvements in the drilling process monitoring dpm system it was possible to quickly efficiently and quantitatively obtain the drilling parameters during rock drilling an in situ drilling test of granite using the improved dpm system showed the sensitivity of the drilling efficiency to each drilling parameter via an orthogonal test the results indicated that the optimal drilling efficiency 13 2 was achieved under the following test conditions a rotation speed of 128 r min thrust force of 788 kpa and a rotation torque of 64 n m the influence of the thrust force on the drilling efficiency was extremely significant the sensitivity of this parameter was high and the weight value of the thrust force had a 57 87 influence among the others furthermore the influence of the rotation torque on the drilling efficiency index was significant the sensitivity to this parameter was neither high nor low and its weight value was 36 82 in contrast the influence of the rotation speed on the index was insignificant sensitivity to this parameter was low and its weight value was 5 31 the research methods and results presented herein can serve as references for the optimum design of drilling construction and the reasonable selection of drilling parameters

preliminary investigation of biogenic gas production in indonesian low rank coals and implications for a renewable energy source indonesia has abundant coal resources at depths suitable to contain substantial volumes of naturally occurring methane which are currently being explored most indonesian coals are thermally immature but are composed of hydrogen rich organic components that are presumed to make them excellent substrates for biogenic methane production gas isotope results from pilot wells in south sumatra reported in this study are interpreted to indicate biogenic origins for the methane corresponding formation water samples were collected and incubated and show the presence of indigenous microbial communities capable of producing methane from indonesian and australian coal although these results are only preliminary they are promising and support the possibility of indonesia developing bio renewable energy from coal seams

paleotempestology database for the western north atlantic basin paleotempestology the study of past tropical cyclone activity has grown considerably over the past two decades and there is now a relatively dense network of sites across the western north atlan

influence of structure and water pressure on the hydraulic conductivity of the rock mass around underground excavations abstract in this study in situ water injection tests and numerical modeling in conjunction with core logs and television image measurements were applied for an investigation of the hydraulic properties of the rock mass around underground excavations the aim of our work was to investigate the influence of rock structure and water pressure on the hydraulic conductivity of the rock mass around underground excavations thus water injection tests were conducted in four boreholes that were drilled in the rock mass in underground tunnels in china seepage connection initiation and steady state seepage were proposed to identify the seepage evolution course within the rock mass by combining the results of pressure and hydraulic conductivity generally hydraulic conductivity is strongly related to rock structure and water pressure the results also revealed that a rearrangement of rock structure would occur in the damage zone resulting in an increase in hydraulic conductivity of nearly one to several orders of magnitude the results from the modified numerical model showed that the pore water distribution and the groundwater inflow rate are affected by both the hydraulic conductivity and the thickness of the damage zone and they are influenced more by the thickness of this zone

genetic and temporal relations between formation waters and biogenic methane upper devonian antrim shale michigan basin usa abstract controversy remains regarding how well geochemical criteria can distinguish microbial from thermogenic methane natural gas in most conventional deposits has migrated from a source rock to a reservoir rarely remaining associated with the original or cogenetic formation waters we investigated an unusual gas reservoir the late devonian antrim shale in which large volumes of variably saline water are coproduced with gas the antrim shale is organic rich of relatively low thermal maturity extensively fractured and is both source and reservoir for methane that is generated dominantly by microbial activity this hydrogeologic setting permits integration of chemical and isotopic compositions of coproduced water and gas providing a unique opportunity to characterize methane generating mechanisms the well developed fracture network provides a conduit for gas and water mass transport within the antrim shale and allows invasion of meteoric water from overlying aquifers in the glacial drift steep regional concentration gradients in chemical and isotopic data are observed for formation waters and gases dilute waters grade into dense brines 300 000 ppm over lateral distances of less than 30 km radiogenic 14c and 3h and stable isotope 18o and d analyses of shallow antrim shale formation waters and glacial drift groundwaters indicate recharge times from modern to 20 000 yr bp carbon isotope compositions of methane from antrim shale wells are typical of the established range for thermogenic or mixed gas 13c 47 to 56 however the unusually high 13c values of co2 coproduced with methane 22 and dissolved inorganic carbon dic in formation waters 28 require bacterial mediation the d values of methane and coproduced formation water provide the strongest evidence of bacterial methanogenesis methane ethane propane ratios and 13c values for ethane indicate 1 the presence of a thermogenic gas component that increases basinward and 2 progressive bacterial oxidation of ethane as the antrim shale subcrop is approached multiple episodes of pleistocene glaciation over northern michigan appear critical to the development of these gas deposits loading of thick ice sheets may have provided hydraulic head that enhanced dilation of preexisting fractures and influx of meteoric water the physical erosion cycle of repeated glacial advances and retreats exhumed the antrim shale around the northern margin of the michigan basin subjecting it to near surface physiochemical and biochemical processes the chemical and hydrologic relations demonstrated in the antrim shale reservoir suggest a dynamic connection between pleistocene glacial history of the midcontinent region and development of recoverable microbially generated natural gas reserves

geological controls on matrix permeability of devonian gas shales in the horn river and liard basins northeastern british columbia canada abstract controls of matrix permeability are investigated for devonian gas shales from the horn river and liard basins in northeastern british columbia canada mineralogy is varied with high carbonate high quartz and moderate quartz carbonate and clay rich strata quartz content varies between 2 and 73 carbonate varies between 1 and 93 and clay varies between 3 and 33 the toc content ranges between 0 3 and 6 wt and porosity varies between about 1 and 7 for horn river basin samples quartz is mainly biogenic in origin derived from radiolarians toc content increases with the quartz content suggesting the toc and quartz both are derived from siliceous phytoplankton a positive relationship between porosity and quartz content is due to the positive relationship between quartz and toc matrix permeability parallel to bedding varies between 7 5e 02 and 7 1e 07 md at an effective stress of 15 mpa variation in permeability is due to a complex combination of factors that includes origin and distribution of minerals pore size distribution and fabric mercury intrusion capillary curves indicate that the higher matrix permeability values 2e 03 md occurs in samples that contain interconnected pore apertures greater than 16 m even when these samples may contain less macropores than low permeability samples the fabric of high permeability samples can be either isotropic or anisotropic however permeability of anisotropic samples is more sensitive to changes in effective stress than isotropic samples more highly anisotropic samples contain moderate amounts of quartz carbonate and in some clay high permeability samples that contain a more balanced ratio between micro meso and macroporosity would not only have faster flow rates but also greater access to sorbed gas within the microporosity compared to samples that lack mesopores several muskwa samples compared to evie and besa river samples contain higher quartz moderate clay and high toc content coupled with high permeability less sensitivity to effective stress and balanced ratios between micro meso and macroporosity would be a lower exploration risk due a greater propensity to fracture the ability to produce and store hydrocarbons due to higher toc contents and greater communication between macropores and micropores in the organic and clay fractions

organic matter hosted pore system marcellus formation devonian pennsylvania the marcellus formation of pennsylvania represents an outstanding example of an organic matter om hosted pore system most pores detectable by field emission scanning electron microscopy fe sem are associated with om instead of mineral matrix in the two wells studied here total organic carbon toc content is a stronger control on om hosted porosity than is thermal maturity the two study wells span a maturity from late wet gas vitrinite reflectance ro 1 0 to dry gas ro 2 1 samples with a toc less than 5 5 wt display a positive correlation between toc and porosity but samples with a toc greater than 5 5 wt display little or no increase in porosity with a further increasing toc in a subset of samples 14 across a range of toc 2 3 13 6 wt the pore volume detectable by fe sem is a small fraction of total porosity ranging from 2 to 32 of the helium porosity importantly the fe sem visible porosity in om decreases significantly with increasing toc diminishing from 30 of om volume to less than 1 of om volume across the range of toc the morphology and size of om hosted pores also vary systematically with toc the interpretation of this anticorrelation between om content and sem visible pores remains uncertain samples with the lowest om porosity higher toc may represent gas expulsion pore collapse that was more complete as a consequence of greater om connectivity and framework compaction whereas samples with higher om porosity lower toc correspond to rigid mineral frameworks that inhibited compactional expulsion of methane filled bubbles alternatively higher toc samples may contain om low initial hydrogen index relatively unreactive that is less prone to development of fe sem detectable pores in this interpretation om type controlled by sequence stratigraphic position is a factor in determining pore size distribution

evidence of similar probablility of intense hurricane strikes for the gulf of mexico over the late holocene hurricane magnitude and frequency have been linked to numerous mechanisms including the steady rise in annual sea surface temperatures el nino southern oscillation enso variations and atmospheric changes in order to better understand those factors that control hurricane magnitude and frequency a long term record spanning the entire gulf of mexico coast is needed here we present a detailed record from ca 5300 900 yr b p of past intense hurricane impacts for cores collected from laguna madre texas united states relative storm intensities were calculated for each event and the average intense storm impact probability for south texas was determined to be 0 46 annual landfall probability previous field studies in western lake florida and lake shelby alabama reveal similar probability intense hurricane strikes of 0 39 although high frequency oscillations between warm and dry and cool and wet climate conditions have occurred in texas through the late holocene there has been no notable variation in intense storm impacts across the northwestern gulf of mexico coast during this time interval implying no direct link between these changing climate conditions and annual hurricane impact probability in addition there have been no significant differences in the landfall probabilities of storms between the eastern and western gulf of mexico during the late holocene suggesting that storm steering mechanisms have not varied during this time

experimental investigation of changes in methane adsorption of bitumen free woodford shale with thermal maturation induced by hydrous pyrolysis this study quantifies the effects of organic matter om thermal maturity on methane ch4 sorption on the basis of five samples that were artificially matured through hydrous pyrolysis achieved by heating samples of immature woodford shale under five different time temperature conditions ch4 sorption isotherms at 35 degrees c 50 degrees c and 65 degrees c and pressures up to 14 mpa on dry solvent extracted samples of the artificially matured woodford shale were measured the results showed that ch4 sorption capacity normalized to toc varied with thermal maturity following1 the trend maximum oil 367 degrees c oil cracking 400 degrees c maximum bitumen early oil 333 degrees c early bitumen 300 degrees c immature stage 130 degrees c the langmuir constants for the samples at maximum oil and oil cracking stages are larger than the values for the bitumen forming stages the total pore volume determined by n 2 physisorption at 77 k increases with increased maturation mesopores 2 50 nm in width were created during the thermal conversion of organic matter and a dramatic increase in porosity appeared when maximum bitumen and maximum oil generation stages were reached a linear relationship between thermal maturity and brunauer emmett teller bet surface area suggests that the observed increase in ch4 sorption capacity may be the result of mesopores produced during om conversion no obvious difference is observed in pore size distribution and pore volume for samples with pores 2 0 nm with the increase of thermal maturity based on co2 physisorption at 273 k the isosteric heat of adsorption and the standard entropy for artificially matured samples ranged from 17 9 kj mol 1 to 21 9 kj mol 1 and from 85 4 j mol 1 k 1 to 101 8 j mol 1 k 1 respectively these values are similar to the values of immature woodford kerogen concentrate previously observed but are larger than naturally matured organic rich shales high temperature hydrous pyrolysis might have induced lewis acid sites on both organic and mineral surfaces resulting to some extent in chemical interactions between the adsorption site and the methane c h bonds the formation of abundant mesopores 2 50 nm within organic matter during organic matter thermal maturation makes a great contribution to the increase in both bet surface area and pore volume and a significant increase in 2 6 nm pores occurs at maximum oil generation and oil cracking to gas ultimately controlling the methane adsorption capacity therefore consideration of pore size effects and thermal maturity is very important for gas in place gip prediction in organic rich shales c 2014 elsevier ltd all rights reserved

microbial degradation of sedimentary organic matter associated with shale gas and coalbed methane in eastern illinois basin indiana usa molecular biodegradation indices for extracts from five pennsylvanian coals and six new albany shale devonian mississippian samples from the eastern part of the illinois basin help constrain relationships between the degradation of biomarkers and the generation of coalbed methane and shale gas investigation of these gas source rocks of varying thermal maturity from different depths facilitates evaluation of the association of microbial degradation with biogenic gas formation distinct from thermogenic processes extensive biodegradation of both aliphatic and aromatic hydrocarbons is observed in the coal extracts whereas in shale extracts only short chain c15 c19 n alkanes from the shallowest depth appear to be microbially altered with minimal evidence for losses of acyclic isoprenoid alkanes and aromatic hydrocarbons by contrast biodegradation of aromatic hydrocarbons specifically alkylated naphthalenes and phenanthrenes occurs in coal extracts in concert with losses of n alkanes attributable to microbial activity thus the progress of hydrocarbon biodegradation in coals differs from the sequence recognized in petroleum where the effects of microbial alteration of aromatic constituents only appear after extensive losses of aliphatic compounds the extent of hydrocarbon biodegradation in these coals also decreases with depth as recorded by the nc25 nc30 index i e abundance relative to 17 h 21 h hopane among the aliphatic constituents and several aromatic compounds methyl dimethyl and trimethylnaphthalenes phenanthrene and trimethyl and tetramethylphananthrenes however the depth variations in the distributions of aliphatic and aromatic hydrocarbons in the shale extracts primarily reflect the effects of thermal maturity rather than biodegradation overall variations in the extent and patterns of biomarker biodegradation among coals and shales likely reflect their distinct microbial consortia that can be attributed to differences in i surviving microorganisms and inoculations from meteoric water ii the characteristics of the sedimentary organic matter especially the preponderance of aromatic constituents in coals and iii the accessibility to that substrate through pores and cleats these results help constrain the processes involved in biodegradation and controls on its extent which in turn assist in recognizing sites favorable for methanogenesis and improved estimates of biogenic gas resources in the illinois basin

using numerical simulation for the prediction of mine dewatering from a karst water system underlying the coal seam in the yuxian basin northern china water inrush from a karst aquifer threatens mine safety in north china because of the special hydrogeological conditions this paper systematically analyzes the regional hydrogeological conditions of the cambrian ordovician limestone karst aquifer in the yuxian basin conceptual and mathematical models of karst water flow system are established and the karst water flow system is simulated by the finite difference method the numerical model is checked using hydraulic head from karst water observation holes and the sensitivity of hydrogeological parameters is analyzed further the risk of water inrush from the karst aquifer underlying the coal seam in the second mining area of the beiyangzhuang mine in the basin is evaluated by the water inrush coefficient method based on the critical hydraulic head for mining safety the rate of mine dewatering is simulated for the three stages of the mining plan with the numerical model the results show that the risk of water inrush in the second mining area is high the rate of dewatering in the three stages without grouting is 1300 1860 and 2050 m3 h respectively and with local grouting is 1020 1550 and 1700 m3 h respectively dewatering combined with grouting not only ensures coal mine safety but also significantly reduces the rate of dewatering the prediction method of mine dewatering has practical significance in engineering applications

void fraction distribution in overburden disturbed by longwall mining of coal voids in overburden disturbed by coal mining provide channels for transfer of heat methane groundwater oxygen exhaust gas and fire fighting materials in the underground environment based on expressions of strata and ground subsidence a group of void fraction distribution models are proposed including porosity in the caved zone the fracture ratio in the bed separation zone and the fissure ratio in the ground subsidence zone combined with a case study of the antaibao coal mine china theoretical calculation and numerical simulation indicate that porosity distribution in the caved zone is u type and the transverse void fractions in the bed separation zone and ground subsidence zone have m type distributions additionally the longitudinal void fraction distribution changes from type to m type along the strike and dip of the coalbed after the complete subsidence of ground the distribution of fractures in the disturbed overburden of the goaf presents a fractured arch and fracture density gradually decreases from arch foot to crown fire prone zones propagating paths of coalbed fires areas prone to water influx and outlets of boreholes used for fire fighting all usually appear around the perimeter of disturbed overburden the transverse void fractions distribution in the bed separation zone changes from type to m type with an increase in the size of the goaf it is suggested that the inlets of gob vent boreholes should be arranged near the center of the bed separation zone in the early stages of longwall mining and around the perimeter in middle to late stages of mining

lake sediment record of late holocene hurricane activities from coastal alabama coastal lake sediments contain a stratigraphically and chronologically distinct record of major hurricane strikes during late holocene time frederic a category 3 hurricane that struck the alabama coast on the gulf of mexico in 1979 left a distinct sand layer in the nearshore sediments of lake shelby as a result of storm tide overwash of beaches and dunes sediment cores taken from the center of lake shelby contain multiple sand layers suggesting that major hurricanes of category 4 or 5 intensity directly struck the alabama coast at ca 3 2 3 0 2 6 2 2 1 4 and 0 8 ka 14 c yr with an average recurrence interval of 600 yr the alabama coast is likely to be struck by a category 4 or 5 hurricane within the next century

biogenic methane and carbon dioxide generation in organic rich shales from southeastern brazil abstract brazilian shale formations are potential biogenic gas systems that are still poorly understood organic rich shales from ponta grossa devonian parana basin irati permian parana basin and tremembe paleogene taubate basin formations were analyzed in order to evaluate their biogenic methane ch 4 generation potential and to constrain environmental and geological conditions that may affect methanogenic metabolism additionally the generation potential of carbon dioxide co 2 was evaluated in combination with ch 4 to constrain brazilian organic rich shales as sources of greenhouse gas to the atmosphere twenty four shale samples were used for batch incubations in dry and wet conditions and after headspace refilling and acetic acid addition during one year physico chemical parameters such as total organic carbon toc specific surface area and pore volume were characterized in order to understand general geologic controls on ch 4 and co 2 production biogenic gas generation rates in dry tests reached up to 3 17 ml t d milliliter per ton of shale per day for ch 4 and 2 45 10 3 ml t d for co 2 during the first 30 days with wet samples producing about 54 more ch 4 and 151 more co 2 than dry samples headspace refilling did not demonstrate significant changes on production rates while acetic acid addition restarted or increased ch 4 and co 2 production rates in several microcosms shales from the irati formation showed the highest methane production rates for both dry and wet tests with unusual ranges of 13 c ch4 and 13 c co2 that may be linked to hydrocarbon biodegradation the studied shale formations have different pore volume and specific surface area but without significant influence over biogenic methane generation

theoretical models for simulating the failure range and stability of inclined floor strata induced by mining and hydraulic pressure abstract there is a risk of floor failure within mining of coal seams above aquifers therefore investigating the processes involved is of great significance for the prediction and prevention of mine water hazards with consideration of the effects of mining pressure and non uniformly distributed hydraulic pressure the two dimensional 2d hydraulic mechanical calculation hm model and the key strata stability analysis ks model were proposed to analyze the theoretical range of failure and the stability of inclined floor strata after mining to validate the model a numerical simulation of the failure characteristics of inclined floor above a confined aquifer was conducted along with an in situ investigation the results showed approximate agreement between the theoretical and simulated failure ranges of the inclined floor along the strike and inclination with their characteristics being approximate to spoon shaped and inverted saddle shaped with upper small lower large respectively the theoretical failure depths of the floor around the mining face side and the upper and lower parts were 13 m 12 5 m and 14 m respectively with general agreement between simulated and measured results moreover the zones prone to water intrusion were indicated to be mainly distributed near the upper end lower end and mining face side of the inclined key strata in good agreement with the distribution of the area disturbed by mining and the risk of groundwater inrush induced by the vertical failure depth the research results could provide an improved understanding of the mechanism of water inrush from underlying aquifers

water inrush and environmental impact of shallow seam mining shallow seam mining is very common in china for enhancing coal recovery however this may cause a series of severe problems in environment and mining safety in some cases because the alluvium aquifers are directly above the shallow coal seams some typical water and sand inrush incidents resulting from shallow mining in china are analyzed based on in situ observation the mining induced strata failures are investigated the height of the fractured zone decreases as the size of the outcrop pillar or mining depth decreases the spatial distributions of the failure zones in the shallow mining have specific features compared to the deep mining these provide an advantageous condition for the shallow mining under alluvial aquifers optimal designs for outcrop pillar sizes are also given in different hydrogeological conditions for environment friendly and production safe mining at shallow depths according to in situ mining experiments in several coalfields technical measures for shallow mining are presented these primarily include the lift mining for thick seams and reduction of the thickness of extraction in the first lift short wall mining and detection of faults and other potential hazards prior to mining

organic facies of the oligocene lacustrine system in the cenozoic taubate basin southern brazil abstract a quantitative study of palynofacies and organic facies was carried out in the cenozoic sedimentary succession of the taubate basin the palaeoenvironmental distributions of particulate organic components were examined in relation to various potential controlling factors lithology depositional environment and stratigraphic sequence about 30 samples were analyzed from a single borehole drilled in sao paulo state this involved rigorous kerogen counts supported by 30 toc and sulphur 20 rock eval pyrolysis and 20 biochemistry analyses in the studied area the oligocene deposits are approximately 600 m thick data was obtained by counting 300 to 500 kerogen particles per sample and then recalculating the percentages of the different constituent groups phytoclast palynomorph and amorphous organic matter aom the kerogen assemblage is palynomorph dominated 70 consisting mainly of freshwater lacustrine algae pediastrum and botryococcus non opaque phytoclasts predominate in most of the kerogen samples however significant variations in the proportion of biostructured and non biostructured brown phytoclasts occur in some intervals the fluorescent aom content occurs in some levels and is composed of two main components an intensively fluorescing structureless organic matter which also has high lipid and protein content indicating a probable bacterial origin for the organic matter microbial mats and terrestrially derived amorphous organic matter which has been reworked to a different extent exhibiting a high content of carbohydrates comparison of the mean kerogen assemblages from different lithologies revealed that the finer grained lithologies generally have higher palynomorph percentages whereas coarser grained lithologies present higher percentages of phytoclasts emphasizing the important role of grain size in organic matter distribution the toc content is generally less than 10 but reaches as high as 44 in some intervals due mainly to the presence of coaly seams the t max spore coloration index and spectral fluorescence measurement values obtained from these samples indicate a low maturity stage the integration of these results together with the organic facies parameters indicate that the analyzed sedimentary section represents a variation from a freshwater lacustrine environment with an oxidant regime to a restricted saline lacustrine environment with a dysoxic anoxic regime there was an excellent correlation between the optical and geochemical parameters

a backbarrier overwash record of intense storms from brigantine new jersey abstract analysis of aerial photographs and historic charts indicates that the barrier beach at brigantine nj has migrated landward 300 to 400 m since 1869 primarily as a result of overwash during hurricanes and winter storms a series of vibracores from the backbarrier salt marsh reveals a millennial scale stratigraphic record of overwash deposition carbon 14 c 14 and cesium 137 cs 137 radioisotopic methods were used to date overwash deposits washovers the ages of recent washovers are consistent with deposition during intense storms in 1938 1944 1950 and 1962 an additional overwash deposit recovered in five of the sediment cores was likely deposited by an intense hurricane strike in 1821 or possibly in 1788 two prehistoric overwash fans were likely deposited by intense storms striking the new jersey coast in the 7th to 14th centuries and 6th to 7th centuries a d the landward barrier migration indicates that the older overwash sediments were likely transported a considerably greater distance than the more recent overwash fans the greater distance of transport may indicate that the prehistoric storms that deposited overwash fans across the study site were more intense than the most intense storm to strike this coast in the historic period the hurricane of 1821 the spatially variable occurrence of overwash deposition at this site points to a need for multisite stratigraphic surveys of extensive stretches of the coast in order to develop reliable records of past intense storm frequency from backbarrier environments

hurricane signatures and landforms toward improved interpretations and global storm climate chronology abstract the correct understanding of the geological and geomorphic evolution of paralic basins and coastal barriers is a prerequisite for establishing holocene hurricane archives worldwide detection and documentation of hurricane signatures in coastal deposits are becoming instrumental in attempts to reconstruct mid and late holocene storm climate history subsurface exploration and field studies on the ne gulf coast and data gleaned from the literature suggest the need for a complex approach that provides well documented details of coastal landscape evolution until recently prehistoric hurricanes and their intensity levels have been automatically interpreted from the frequency and thickness of sand layers in muddy paralic deposits however in addition to wind velocity several hydro aerodynamic and other factors a wide range of stratigraphic conditions topographic setting and sand sources also determine variations in the extent and intensity of storm flooding erosion transfer and deposition of sand layers in small paralic basins inherent limitations in these sedimentary records and their interpretation must be overcome in order to improve local hurricane chronologies and establish interregional correlations before sedimentary and chemical signatures are accepted as diagnostic indicators of overwash especially by catastrophic hurricanes alternative causes must also be considered a parallel scale of storm flood level stages should supplement the saffir simpson hurricane categories the relationship between storm intensities and flooding elevations is highly complex changes in sea level shore positions formation and extinction of preexisting incised valley networks the impact of transgression and regression processes on estuaries and their deposits play determining roles in setting the stage for overwash processes strandplain progradation followed by erosive shore retreat played a key role in framing certain paralic lakes without overwash sand layers and marine microfossils may be also emplaced by storm driven currents that enter unobstructed estuaries inlets and storm breaches bioturbation also distorts the storm record significant lateral variations in the number and thickness of intercalated sand layers at closely adjacent sites suggest the importance of local differences in sources transport and preservation processes in the dimensions relative positions and accessibility of sand resources inside and adjacent to coastal basins variations in the number thickness and ages of sand laminae may not be related to the number of storms and their intensities this may impair correlations between regionally interpreted calm and intensive phases in partial overlap with an assumed quiescent storm phase stable isotope ratios in lacustrine muds impacted by salt water influx reveal frequent hurricane activity during the last 1 5 ka as well by mimicking effects of reduced storminess the fewer and thinner sand laminae deposited between 7 0 and 3 4 ka b p may be attributed to greater distances of estuarine landward transport by storm tidal currents at times of lower sea levels

role of hurricanes in the holocene stratigraphy of estuaries examples from the gulf coast of florida abstract sarasota and little sarasota bays are shallow coastal bays located landward of a holocene barrier inlet complex on the west central microtidal gulf coast of florida sediments presently accumulating in the bay consist of 1 fine to very fine quartz sand contributed from the gulf shoreline during storm generated washover through tidal inlets and from reworking of older deposits 2 fine sand to pebble sized quartz and phosphatic sediment contributed by tertiary and pleistocene deposits 3 biogenic carbonate debris which is produced within the bays and or derived from the gulf of mexico 4 clay minerals derived from weathering of tertiary and pleistocene carbonates and clays and 5 particulate organic debris interpretations from 51 vibracores from throughout the bays have enable delineation of four major depositional sedimentary facies resulting from specific environmental conditions protected bay open bay tidal delta washover and storms bedrock in the area ranges from 0 to about 8 m msl and is largely responsible for the areal configuration of the bay and the location of the barrier islands the holocene stratigraphy of both bays has been greatly influenced by the passage of major hurricanes which carried large volumes of sand and shell gravel into the bays at least four of these storms are documented in these cores three storm units from sarasota bay have been radiocarbon dated at 2 270 1 320 and 240 years before present ybp historically documented severe hurricanes influenced this coast in 1848 and 1921 hurricanes interrupted the normal low energy slow deposition in the bays and caused inlets to open and close three storm generated sedimentary facies are identified 1 a graded storm facies which is composed of conspicuously fining upward units ranging from sandy shell gravel to slightly shelly quartz sand 2 a homogenous storm facies consisting of homogenous and relatively thin shelly sand and gravel units and 3 a fluvial storm facies which is muddy and generally free of shells representing terrigenous influx from runoff

sedimentary evidence of hurricane strikes in western long island new york 1 evidence of historical landfalling hurricanes and prehistoric storms has been recovered from backbarrier environments in the new york city area overwash deposits correlate with landfalls of the most intense documented hurricanes in the area including the hurricanes of 1893 1821 1788 and 1693 a d there is little evidence of intense hurricane landfalls in the region for several hundred years prior to the late 17th century a d the apparent increase in intense hurricane landfalls around 300 years ago occurs during the latter half of the little ice age a time of lower tropical sea surface temperatures multiple washovers laid down between 2200 and 900 cal yr b p suggest an interval of frequent intense hurricane landfalls in the region our results provide preliminary evidence that fluctuations in intense hurricane landfall in the northeastern united states were roughly synchronous with hurricane landfall fluctuations observed for the caribbean and gulf coast suggesting north atlantic wide changes in hurricane activity

microbial production and modification of gases in sedimentary basins a geochemical case study from a devonian shale gas play michigan basin an expanded data set for gases produced from the antrim shale a devonian black shale in the michigan basin united states has allowed for a detailed examination of the related chemical and isotopic compositional changes in the solid gas liquid systems that discriminate between microbial and thermogenic gas origin in the antrim shale economic microbial gas deposits are located near the basin margins where the shale has a relatively low thermal maturity and fresh water infiltrates the permeable fracture network the most compelling evidence for microbial generation is the correlation between deuterium in methane and coproduced water along the basin margins there is also a systematic enrichment in 13c of ethane and propane with decreasing concentrations that suggests microbial oxidation of these thermogenic gas components microbial oxidation accounts not only for the shift in 13c values for ethane but also in part for the geographic trend in gas composition as ethane and higher chain hydrocarbons are preferentially removed this oxidation is likely an anaerobic process involving a syntrophic relationship between methanogens and sulfate reducing bacteria the results of this study are integrated into a predictive model for microbial gas exploration based on key geochemical indicators that are present in both gas and coproduced water one unequivocal signature of microbial methanogenesis is the extremely positive carbon isotope values for both the dissolved inorganic carbon in the water and the coproduced co2 gas in contrast the 13c value of methane is of limited use in these reservoirs as the values typically fall between the commonly accepted fields for thermogenic and microbial gas in addition the confounding isotopic and compositional overprint of microbial oxidation increasing the values to typically thermogenic values may obscure the distinction between methanogenic and thermogenic gas

palaeohurricane reconstructions from sedimentary archives along the gulf of mexico caribbean sea and western north atlantic ocean margins hurricanes annually threaten the atlantic ocean margins historical hurricane records are relatively short and palaeohurricane sedimentary archives provide a geological and climatic context that sheds light on future hurricane activity here we review palaeo trends in hurricane activity elucidated from sedimentary archives we discuss dating methods site selection and stat istics associated with previously published records these archives have been useful for under standing the long term evolution of coastal systems and the response of intense hurricane activity to climatic changes regional shifts in hurricane overwash on centennial to millennial timescales have been linked to various climatic modes of variability including el nino southern oscillation and the north atlantic oscillation but could also reflect regional scale controls on hurricane activity

the biogenic methane potential of european gas shale analogues results from incubation experiments and thermodynamic modelling abstract core samples from the lower jurassic posidonia shale lower toarcian wealden black shales both from the lower saxony basin northern germany and from the cambrian ordovician alum shale southern sweden have been investigated for their biogenic gas potential in incubation experiments the sample set represents all stages of thermal maturity from immature to overmature methane and to a higher degree carbon dioxide are generated from all samples by added microorganisms in general overmature samples rr 1 5 show lowest gas generation rates the highest generation rates for produced methane up to 89 mol g 1 day 1 and carbon dioxide 139 mol g 1 day 1 were detected in immature alum shale samples when different hydrocarbon degrading inocula where added whereas the lowest methane production rates were detected in wealden sediments the lightest 13c values for produced methane and carbon dioxide have been detected in posidonia shale samples of oil window maturity such samples are some of the most sensitive for gas generation and exhibit the strongest decreases of hydrogen indices after incubation hydrogeochemical modelling of methane generation fate and behaviour showed that methane formed during the early diagenesis got lost from posidonia shale the mainly investigated shale in this study as the mature posidonia shale is according to the incubation experiments still sensitive for gas generation a production scenario of generically generated methane due to oil degradation is simulated the basic conditions resemble the conditions in the antrim shale in the michigan basin gas production due to dewatering and pressure decrease results in an increase of the gas volumes coupled to a progressive enrichment of carbon dioxide in the produced gas moreover calcite scaling may be the consequence during progressive production similar to the antrim shale in the michigan basin such calcite precipitation has been demonstrated to predominantly occur in natural samples at oil window maturity

finite element modeling of stress distributions and problems for multi slice longwall mining in bangladesh with special reference to the barapukuria coal mine abstract this paper deals with current coal mining operations under a mega aquifer in nw bangladesh and presents a case study of underground mining in barapukuria the study uses numerical analyses to evaluate stress redistribution strata failure and water inflow enhancements that result from these coal extraction operations a total of three models a b and c are presented in this study two dimensional numerical modeling was performed to analyze the deformation and failure behavior of rock elements for two different models a and b for model a we used an elastic finite element software package considering a mohr coulomb failure criterion for model b we used boundary element method bem the first two models were applied to determine the stress patterns model a provides the tectonic stress pattern of the basin whereas model b represents the mining induced stress field the third model is a schematic model the results of model a show that tensional failure of rock elements is concentrated in the gondwana coal sequences as well as within the eastern boundary fault ebf and its surroundings failure occurs in the middle to lower part of the model and the magnitude of tensional stress in the shallow part is much greater than in the deeper part contours of max magnitudes are attributed to up bending of the overburden which would create numerous upward propagating fissures fractures the results of model b show that fracture propagation would be about 240 m upward for single slice height 3 m mining extraction from the contours of mean stress magnitudes it is observed that the high range of fracture propagation increased upward for multi slice extraction of coal it is apparent from the fracture heights that large amounts of caving would occur towards the roof due to the multi slice extraction of coal and finally would be linked with the water bearing dupi tila formation if this happened it would ultimately cause a major water inflow hazard in the mine

incubation experiments to constrain the production of methane and carbon dioxide in organic rich shales of the permian irati formation parana basin abstract the permian irati formation in brazil hosts organic rich shales and heavy hydrocarbons suitable for biogenic production of methane ch4 and carbon dioxide co2 in this study shale samples from the irati formation were used in laboratory incubation experiments performed under different temperatures 22 c 50 c 70 c and 80 c to evaluate the generation of ch4 and co2 under thermal conditions compatible with biodegradation in shallow gas systems

reconstruction of paleostorm events in a coastal lagoon herault south of france article i nfo finding records of past catastrophic storm events is essential to evaluate the long term climatic evolution in a given coastal area this question has been addressed by the study of sediment cores sampled in a small coastal lagoon of the french mediterranean coast pierre blanche lagoon two cores were studied in detail and revealed the presence of three main storm events the sedimentation rates calculated using the cfcs 210 pb model in agreement with 137 cs data are 3 0 4 and 4 2 0 7m m y 1 near the border and in the center of the lagoon respectively this suggests that the 0 6 m deep lagoon could be filled with sediments over the next 150 yr our study shows that storm events can be characterized in sedimentary sequences identified by facies grain size and faunal assemblages lagoonal and marine species comparison of 210 pb 14 c chronology and historical accounts suggest that the three identified

hydrochemical characteristics of groundwater movement and evolution in the xinli deposit of the sanshandao gold mine using fcm and pca methods the objective of this study is to characterize the physicochemical properties of groundwater in the sanshandao gold deposit analyze the laws of motion and evolution of the groundwater system and provide evidence for the design of undersea mining and safety warnings using combined fuzzy c means fcm and principal component analysis pca methods thirteen physicochemical indicators and two isotopic indicators were surveyed from 100 fissure water samples and 13 typical water samples from xinli a deposit of the sanshandao gold mine in china first pca was used to extract four pcs with explained variances 48 25 10 and 7 and the characteristics of the hydrochemistry indicators of each pc were examined the four pcs are identified as the processes of concentration and dilution sericite rock orientation and carbonatization potash feldspathization and dissolution of carbon dioxide next using the four pcs developed from pca 100 fissure water samples were grouped into four spatially continuous clusters using the fcm cluster method with the aid of graphic technology the four fuzzy clusters were determined as deep saline water shallow saline water bedrock brine and mixed wastewater following careful analysis of the hydrochemical characteristics of each cluster combined with a related hydrogeological report finally further analysis of the pca and fcm results determined factors constituting the groundwater system including sources of water flow path mixing zone local fissure zone and impact of mining on the groundwater system this study shows that the combination of pca and fcm is important for understanding hydrochemical characteristics of a groundwater system

sedimentary evidence of intense hurricane strikes from new jersey nine vibracores from the backbarrier marsh at whale beach new jersey reveal three large scale overwash deposits associated with historic and prehistoric storms the uppermost and smallest overwash fan was deposited in the ash wednesday northeaster of march 5 8 1962 a second more substantial overwash fan between 100 and 35 cm depth dates to the late eighteenth or early nineteenth century this fan was most likely deposited during the 1821 hurricane the only intense hurricane to make landfall in new jersey in the past 350 yr a third larger overwash fan between 200 and 300 cm depth was deposited between a d 1278 and 1438 and is likely the result of a prehistoric intense hurricane strike the combination of historical and stratigraphic evidence indicates that two intense hurricanes winds 50 ms 21 have likely made landfall on the southern new jersey coast in the past 700 yr resulting in an annual landfall probability of 0 3

aromatic hydrocarbons in the paraiba valley oil shale abstract aromatic hydrocarbon fractions extracted from different depths of a core 13 8 47 3 m deep of the paraiba valley oil shale were analysed by computerized high resolution gas chromatography mass spectrometry triterpenes derived from precursors oxygenated at position 3 such as tetracyclic ring a degraded and pentacyclic aromatic ursane oleanane and lupane derivatives were amongst the most common components indicating an important input from higher plants to the sediment this interpretation is supported by the occurrence of sesquiterpenoids cadalene calamenene in the same sediment samples on the other hand hopanoids notably the tetraaromatic derivative were also detected attesting to a significant bacterial contribution to the sedimentary biomass in contrast with the abundance of aromatic structures related to oleanane ursane and hopane no skeletons traceable to steroidal precursors could be confirmed suggesting a small algal input this study also revealed the presence of two new aromatic biomarkers one of them is a c24 monoaromatic tetracycle apparently derived via ring a degradation from a triterpenoid with the fernene skeleton the other compound is a ring a monoaromatic pentacycle with what appears to be a hopanoid structure

dual porosity poroelastic analyses of wellbore stability this paper presents a numerical solution of dual porosity poroelastic formulations that couple solid deformations with fluid flow in both matrix and fracture systems of naturally fractured reservoirs the finite element numerical method was applied to solve the inclined wellbore problem in which mud weight was considered for both permeable and impermeable boundary conditions failure criteria relevant to tensile collapse and shear failure modes were introduced into the numerical model and resulting failure areas around boreholes were subsequently defined several related applications including the stability of inclined and horizontal wellbores under various in situ stress regimes were evaluated upper and lower mud weight bounds and the most stable borehole orientations were determined the best trajectory selections for horizontal boreholes were also investigated

spatial variations in major u s hurricane activity statistics and a physical mechanism abstract the authors provide a statistical and physical basis for understanding regional variations in major hurricane activity along the u s coastline on long timescales current statistical models of hurricane activity are focused on the frequency of events over the entire north atlantic basin the exception is the lead author s previous work which models the occurrence of hurricanes over the caribbean sea gulf of mexico and the southeast u s coast separately here the authors use statistics to analyze data from historical and paleoclimatic records to expand this work in particular an inverse correlation in major hurricane activity across latitudes at various timescales is articulated when activity is above normal at high latitudes it tends to be below normal at low latitudes and vice versa past research paleoclimatic records and historical data hint at the potential of using the north atlantic oscillation nao as an indicator of where storms will likely track over long timescales an excite

reconstruction of prehistoric landfall frequencies of catastrophic hurricanes in northwestern florida from lake sediment records abstract sediment cores from western lake provide a 7000 yr record of coastal environmental changes and catastrophic hurricane landfalls along the gulf coast of the florida panhandle using hurricane opal as a modern analog we infer that overwash sand layers occurring near the center of the lake were caused by catastrophic hurricanes of category 4 or 5 intensity few catastrophic hurricanes struck the western lake area during two quiescent periods 3400 5000 and 0 1000 14 c yr b p the landfall probabilities increased dramatically to ca 0 5 per yr during an hyperactive period from 1000 3400 14 c yr b p especially in the first millennium a d the millennial scale variability in catastrophic hurricane landfalls along the gulf coast is probably controlled by shifts in the position of the jet stream and the bermuda high

an application of hydraulic tomography to a deep coal mine combining traditional pumping tests with water inrush incidents abstract water inrush incidents threaten the safety of coal mining understanding of hydrogeologic parameter distributions is critical for preventing water related hazards in coal mines during the deep mining 1000 m under the north china plain water from water bearing strata discharges into coal seams through geologic conduits i e water inrush due to the fractured zone under the floor of working faces in this study a water inrush incident was exploited as an active stimulus a 3d groundwater flow model was built for the eighth member of the middle ordovician system in xingdong coal mine using this model and an inverse approach we first checked if the data from the incident and an independent pumping test carry non redundant information about the heterogeneity of the mine afterward we combined these datasets to conduct a large scale approximately 10 km hydraulic tomography ht analysis the estimated hydraulic conductivity distribution from the ht analysis is found consistent with the distribution of known geologic faults that is a cluster of faults is characterized as a high conductivity zone a high conductivity zone is identified at locations close to the water inrush location which is the high cement consumption zone during the grouting project finally results of this study promote exploiting the water inrush events as a ht survey for mapping geologic structures over a large area

sediment dynamics and hydrographic conditions during storm passage waquoit bay massachusetts abstract the impact of storm events on the sediment dynamics of the shallow groundwater fed estuaries of cape cod massachusetts usa is little understood to address this the objectives of this study are to assess sediment dynamics during storm passage and determine whether shallow back barrier lagoons like waquoit bay have the preservation potential for a sedimentary archive of hurricanes when setting out in this study it was unclear whether paleotempestological methods could be applied successfully to cores collected from the landward reaches of shallow estuaries of southern new england water level and bottom current data using arm and float tide gauges and seahorse tilt current meters was collected during tropical storm irene 2011 and coupled with storm surge modeling projections to better elucidate storm induced sediment transport mechanisms three sediment cores were collected at the head of waquoit bay located 2 8 km from the barrier beach grain size analysis of sediment cores was conducted with a laser particle size analyzer at 1 cm increments in order to identify coarse grain anomalies which can act as a storm event proxy bayesian statistics were applied to develop age models of two of the cores based on three pb pollution chronomarkers and 21 continuous flow 14c ams ages the results yield variable sediment accumulation rates between 2 mm yr to 10 mm yr with significantly higher rates occurring in the upper 1 m of sediments grain size results are highly variable and contain numerous large amplitude short duration fluctuations suggesting that during storm passage coarse sand is deposited in the coring site the sensitivity of the site to both tropical and extratropical storm events uncertainties in the age model and the multiple sediment sources and transport pathways limits the utility of using the waquoit sediments to determine long term hurricane frequencies results nonetheless provide insights into how extreme storm events impact coastal lagoons

geological controls and estimation algorithms of lacustrine shale gas adsorption capacity a case study of the triassic strata in the southeastern ordos basin china abstract high pressure methane adsorption experiments on a series of triassic lacustrine shale moisture equilibrated samples from the southeastern ordos basin china were conducted at pressure up to 20 mpa two of which were measured at 30 c 40 c 50 c 60 c and 70 c and seven were performed under reservoir temperature from 48 c to 62 c to investigate the effect of organic matter content maturity mineralogical compositions and reservoir conditions temperature and pressure on the methane sorption capacity the total organic carbon contents tocs range from 0 91 wt to 6 11 wt the thermal maturities as inferred from rock eval analysis range from low mature to high mature the minerals of the shale samples are dominated by clays 36 57 wt and quartz 19 44 wt for the entire shale samples the dominant clay minerals are mixed layer illite smectite with some illite and no smectite exists corresponding to a stage of late diagenesis the studied samples have n2 bet surface areas ranging between 1 47 and 9 21 m2 g and pore volumes of 0 013 0 034 cm3 g the methane sorption capacities of moisture equilibrated shale samples show a positive correlation with toc contents and bet surface areas no relationship was observed between the clay contents and methane sorption capacities indicating that clay minerals do not significantly contribute to methane sorption capacity in these organic shales the langmuir pressure pl increases exponentially with temperature and the langmuir volume vl decreases linearly with temperature a computational scheme has been developed to calculate the methane sorption capacity of shales as a function of toc content temperature and pressure based on langmuir sorption isotherm function using this algorithm methane sorption capacity of organic shales as function of depth can be obtained due to the predominating effect of pressure the methane sorption capacity increases with depth initially through a maximum and then decreases due to the influence of increasing temperature at a greater depth the maximum gas sorption capacity typically occurs at a depth range between 400 and 900 m with toc content increasing the maximum methane sorption capacities of organic shales and the corresponding depths increase

geology of microtidal coastal lagoons rhode island abstract the coastal lagoons of rhode island are contained behind narrow 200 300 m wide barrier spits in a microtidal wave dominated environment the major depositional environments within the lagoons are 1 flood tidal deltas 2 subtidal storm surge platforms and 3 back lagoon low energy basins the pathways of sediment influx into the coastal lagoons are 1 tidal inlets breachways 2 temporary storm surge channels cut through the barrier spits and 3 overwash transport of sand that crosses the spits and builds into the lagoons sediment transport in the lagoons is caused by currents generated by windshear within the lagoon basins and by storm surge generated flow both of which may be additive to tidal currents lagoonal sedimentation was initiated in ninigret pond approximately 4100 b p based on radiocarbon dating as low energy basins developed on an uneven pleistocene glaciofluvial surface tidal delta sedimentation began approximately 2500 b p the continued existence of the lagoons is dependent on rate of infill and barrier retreat versus rate of sea level rise based on long term sea level rise past 2500 years calculations indicate that the lagoons will decrease in size as sediment influx exceeds the rate of inundation

characterizing the pore structure in the silurian and permian shales of the sichuan basin china abstract nitrogen sorption and mercury intrusion methods were applied to characterize the pore structure of the lower silurian shales of the long ma xi formation and upper permian shales of the da long formation in the sichuan basin the results indicate that the specific surface areas and porosities of the silurian shales are in the range of 17 83 29 49 m 2 g and 3 65 18 26 respectively the silurian shales show a bimodal pore size distribution and consist of both micropores and nanopores ranging from 30 to 60 m and 1 7 20 nm respectively a strong positive linear correlation between the surface areas and total organic carbon content toc suggests that the organic matter contributes mostly to the amount of specific surface area of the silurian shales whereas the contribution of clay minerals appears to be negligible the organic matter also accounts for 50 70 of the porosity in the silurian shales soluble organic matter in the form of bitumen however has a negative impact on the surface area and porosity of the silurian shales and reduce the amount of surface area and porosity in these shales for the permian shales their surface area and porosity are lower than those of the silurian shales and are in the ranges of 2 20 3 52 m 2 g and of 1 30 4 15 respectively the pore size distribution of the permian shales shows a unimodal pattern of micropores in a size range of 30 60 m their toc and clay mineral contents display poor correlation with the surface areas and suggest that both the organic matter and clay minerals have very low surface areas a clear negative correlation between the porosity and toc in the permian shales indicates that organic matter contributes little or insignificantly to the porosity due to poorly developed organic pores in kerogen because the permian shales are much lower in thermal maturity than the silurian shales furthermore there is a consistent negative linear correlations between the bitumen content and the porosity for both the permian shales and silurian shales and indicate that the bitumen may significantly reduce the porosity of the shales by occupying the pore spaces in the mineral and organic matrix finally it is clear that the lower silurian shales have a greater shale gas potential than the upper permian shales do based on their surface area and porosity

investigations of water inrushes from aquifers under coal seams in many coal mines limestone confined aquifers underlie coal seams during coal extraction from these mines water inrushes occur frequently with disastrous consequences this paper introduces the hydrogeological conditions of the coal mines and the potential water inrush disasters from aquifers under coal seams it then presents the water inrush mechanism the main factors which control water inrushes include strata pressure mining size geologic structures and the water pressure in the underlying aquifer analysis shows that reduction of confinement due to mining is the major cause of the water conducting failure in the floor strata the depth of the failure zone is strongly dependent on the mining width this paper also presents field observation results of the water conducting failure in the floor strata and applies the finite element method coupled with stress dependent permeability to analyze hydraulic conductivity enhancement due to coal extraction finally theoretical and empirical methods to predict water inrushes are given and technical measures for improving mine design and safety for coal extraction over aquifers are presented these measures include fault and fracture grouting and mining method modification such as changing long wall to short wall mining

a decadally resolved paleohurricane record archived in the late holocene sediments of a florida sinkhole article i nfo a 4500 year record of hurricane induced storm surges is developed from sediment cores collected from a coastal sinkhole near apalachee bay florida recent deposition of sand layers in the upper sediments of the pond was found to be contemporaneous with significant historic storm surges at the site modeled using slosh and the best track post 1851 a d dataset using the historic portion of the record for calibration paleohurricane deposits were identified by sand content and dated using radiocarbon based age models marine indicative foraminifera some originating at least 5 km offshore were present in several modern and ancient storm deposits the presence and long term preservation of offshore foraminifera suggest that this site and others like it may yield promising microfossil based paleohurricane reconstructions in the future due to the sub decadal 7 years resolution of the record and the site s high susceptibility to hurricane generated storm surges the average local frequency of recorded events approximately 3 9 storms per century is greater than that of previously published paleohurricane records from the region the high incidence of recorded events permitted a time series of local hurricane frequency during the last five millennia to be constructed variability in the frequency of the largest storm layers was found to be greater than what would likely occur by chance alone with intervals of both anomalously high and low storm frequency identified however the rate at which smaller layers were deposited was relatively constant over the last five millennia this may suggest that significant variability in hurricane frequency has occurred only in the highest magnitude events the frequency of high magnitude events peaked near 6 storms per century between 2800 and 2300 years ago high magnitude events were relatively rare with about 0 3 storms per century occurring between 1900 and 1600 years ago and between 400 and 150 years ago a marked decline in the number of large storm deposits which began around 600 years ago has persisted through present with below average frequency over the last 150 years when compared to the preceding five millennia

700 yr sedimentary record of intense hurricane landfalls in southern new england five intense category 3 or greater hurricanes occurring in 1635 1638 1815 1869 and 1938 have made landfall on the new england coast since european settlement historical records indicate that four of these hurricanes 1635 1638 1815 and 1938 and hurricane carol a strong category 2 storm in 1954 produced significant storm surges 3 m in southern rhode island storm surges of this magnitude can overtop barrier islands removing sediments from the beach and nearshore environment and depositing overwash fans across back barrier marshes lakes and lagoons in a regime of rising sea level accumulation of marsh lake or lagoon sediments on top of overwash deposits will preserve a record of overwash deposition we examined the record of overwash deposition at succotash salt marsh in east matunuck rhode island and tested the correlation with historical records of intense storms aerial photographs taken after hurricanes in 1954 and 1938 show overwash fans deposited at the site analysis of 14 sediment cores from the back barrier marsh confirmed the presence of these fans and revealed that 4 additional large scale overwash fans were deposited within the marsh sediments the four overwash fans deposited since the early seventeenth century at succotash marsh matches the historical record of significant hurricane induced storm surge these fans were most likely deposited by hurricanes in 1954 1938 1815 and either 1638 or 1635 radiocarbon dating of two prehistoric overwash fans indicated that these were deposited between a d 1295 1407 and 1404 1446 and probably represent intense hurricane strikes in the past 700 yr at least 7 intense hurricanes struck the southern rhode island coast and produced a storm surge that overtopped the barrier at succotash marsh

a preliminary study on the characterization and controlling factors of porosity and pore structure of the permian shales in lower yangtze region eastern china abstract permian organic rich shales occur throughout the lower yangtze region in eastern china and are potentially a future target for shale gas exploration due to the lack of data the gas potential of these permian shales is difficult to evaluate in this study a total of 22 permian shale samples were collected from two wells and their geochemical and rock property porosity characteristics were investigated the results show that the samples have a total organic carbon toc content of 0 6 17 4 wt derived from mainly gas prone kerogen with a vitrinite reflectance ro value ranging from 2 3 to 2 7 total porosity of the samples ranges between 1 and 5 5 the micropore and mesopore surface areas range between 5 41 35 69 m2 g and 3 59 11 23 m2 g respectively micropore and mesopore volumes range between 0 22 1 44 cm3 100 g and 0 67 1 76 cm3 100 g respectively total porosity and pore structure data of these samples show a correlation with toc for samples with toc 12 wt negative correlation relationships were observed toc content strongly impacts gas storage capacity of the permian shales in the lower yangtze region and the preliminary results of the present study have important implications for the shale gas play evaluation in this area

the genesis and evolution of carbonate minerals in shale oil formations from dongying depression bohai bay basin china abstract shale oil is attracting increasing attention in the petroleum industry as an essential target of unconventional oil and gas exploration recent exploration efforts have indicated that laminar carbonates are closely related to the favorable depositional strata of shale oil this research focused on inter bedded layers of laminar carbonates as well as mudstone and shale in the dongying depression of the bohai bay basin in eastern china and attempted to reveal the genesis and evolution of the carbonates by means of drill core observations thin sections high resolution scanning electron microscopic observations and fluorometric cathodoluminescence and geochemical analyses the results demonstrated that 1 the carbonates could be categorized into two groups crystalline carbonates and micritic carbonates 2 the crystalline carbonates were well crystallized and greenish under fluorescent light and 3 the micritic carbonates were not well crystallized and had biotic textures it was discovered that the crystalline carbonates were mainly developed in the shale layer and were formed from the late filling effects of the diagenetic cracks along the shale fissility planes shale layers with crystalline carbonates are usually favorable for shale oil reserves the micritic carbonates were formed from direct deposition controlled by biological effects in the stratified flows of the seasonal lake basins and are unfavorable for shale oil reserves

coal strength and young s modulus related to coal rank compressional velocity and maceral composition abstract this paper presents an experimental investigation of coal rank and maceral composition influences on the coal mechanical behaviors the complete stress strain behavior uniaxial compressive strength young s modulus and acoustic compressional velocity were measured and correlated to coal ranks and microstructures the test results show that coal is an elasto brittle geo material and its uniaxial compressive strength and young s modulus increase as coal rank increases this occurs because as vitrinite reflectance or coal rank increases coal has less microporous structure and thus higher uniaxial compressive strength therefore using vitrinite reflectance value instead of vitrinite content is advantageous for correlating coal strength the experimental results also demonstrate that compressive strength and young s modulus have positive exponential correlation even for different types of coal therefore the compressive strength of coal is highly related to its young s modulus the uniaxial compressive strength and acoustic compressional velocity of coal are also correlated but a single correlation does not exist for different coal ranks instead different relationships occur for different types of coal

deformation failure and permeability of coal bearing strata during longwall mining abstract to mitigate water shortage a few groundwater reservoirs are being built at the daliuta coal mine shaanxi province china it is essential to investigate the deformation failure and permeability of coal bearing strata during longwall mining and their influences on the construction of groundwater reservoirs in this paper the local geology was introduced briefly and the complete stress strain and permeability for different rock samples were investigated using laboratory experiments and then a three dimensional coupling model between stress and permeability was proposed after that a series of numerical simulation was performed to investigate the dynamics of stress permeability coefficient using flac3d it turns out that due to the relatively low mechanical strength of the coal bearing strata at the daliuta coal mine there are only two zones above the goaf that is caving zone and fracture zone and the fracture zone extends directly to the surface the rock mass permeability is closely related to the stress strain and the permeability decreases with the rise of stress in the stage of elastic deformation while it increases significantly in the stages of plastic deformation and failure the maximum value of permeability coefficient appears in the stage of strain softening and the value varies greatly with the rock lithology during the advancement of longwall face the redistribution range is much wider for permeability than for rock failure and the permeability is the largest on the periphery of goaf rock mass with increased permeability is horizontally oval shaped and vertically saddle shaped the permeability of coal seam roof and floor experiences three stages decrease increase and gradual recovery during coal mining the results are in good agreement with those of physical modeling and field observation the outcomes may contribute to the site selection and construction of the groundwater reservoir at the daliuta coal mine

hydrogeological analysis and salvage of a deep coalmine after a groundwater inrush this paper presents a case history of the permanent salvage of the sanhejian coalmine in china after a sudden groundwater inrush which includes emergency responses hydrogeological analyses and design and performance of bulkheads the inrush accident occurred in october 2002 in the mined out area with a high water pressure of 7 6 mpa and a high water temperature of 51 c the emergency response quickly followed up to provide the time required to perform a detailed hydrogeological analysis to identify the source and pathway of groundwater the sanhejian coalmine is geologically located in the tengxian anticline hydrogeological setting the sunshidian fault the northern boundary of the mine was assumed impermeable in the original hydrogeological report after the accident and hydrogeological analysis this assessment was revised and the fault was considered to be permeable the sunshidian fault connects the strata in the mine and the excellent water productive middle ordovician majiagou formation in the core of the tengxian anticline it was concluded that the water inrush was from the underlying ordovician karst aquifer and the pathway was a hidden tectonic structure in the strata overlying the aquifer this assessment served as the guideline for salvaging the mine in this project after a detailed technical and economic analysis a concrete bulkhead design was selected from several alternatives including dewatering and surface grouting the performance of the bulkheads has been sufficient for the last 6 years since their construction this case history shows that the hydrogeological analysis plays an essential role in successfully salvaging the coalmine from the water inrush by identifying the source and pathway of groundwater

a 1200 year proxy record of hurricanes and fires from the gulf of mexico coast testing the hypothesis of hurricane fire interactions abstract we present here the first high resolution pollen record of vegetation response to interactions of hurricane and fire disturbances over the past 1200 yr from a small lake in alabama on the gulf of mexico coast the paleotempestological record inferred from the overwash sand layers suggests that the alabama coast was directly struck by saffir simpson category 4 or 5 hurricanes twice during the last 1200 yr around 1170 and 860 cal yr bp suggesting an annual landfall probability of 0 17 for these intense hurricanes the charcoal data suggest that intense fires occurred after each of these hurricanes the pollen data suggest that populations of halophytic plants chenopodiaceae and heliophytic shrubs myrica expanded after the hurricane strikes probably due to saltwater intrusion into the marshes and soil salinization caused by overwash processes populations of pines pinus sp decreased significantly after each intense hurricane and the ensuing intense fire suggesting that repeated hurricane fire interactions resulted in high tree mortality and probably impeded recruitment and recovery our data support the hypothesis that the likelihood and intensity of fire increased significantly after a major hurricane producing responses by vegetation that are more complex and unpredictable than if the disturbance agents were acting singly and independently

interpreting sea level rise and rates of vertical marsh accretion in a southern new england tidal salt marsh an investigation of marsh accretion rates on a new england type high marsh barn island wildlife management area stonington connecticut reveals that this system is sensitive to changes in sea level and storm activity and the peat can accurately record rates of relative submergence as determined by tide gauge records over intervals of 2 5 decades the results also suggest that the relationship between the accretion deficit and plant community structure is important when utilizing peat records to reconstruct historic sea level curves within stablespartina patenshigh marsh communities in systems where major vegetation changes are prominent over short periods of time 50 years interpretations of sea level rise should be limited to the system in which they are developed unless careful vertical controls can be maintained on the data and multiple datable horizons can be identified within the substrate the results of this investigation further show that in a stablespartina patenscommunity within this particular system there is little vertical translocation of137cs making this isotope a powerful tool for assessing rates of vertical marsh development since 1954

contrasting sediment records of marine submersion events related to wave exposure southwest france abstract sediment records of two contrasting backshore coastal marshes extremely vulnerable to recent and historical marine flooding events located on the sw coast of france have been investigated using a multiproxy approach the studied marshes are 30 km apart and have been flooded by similar storm events 7 marine floods in the last 250 years one is located in a wave exposed coast but isolated from the sea by a sediment barrier whereas the other is located in a sheltered estuarine environment and isolated from the sea by a dike one core was collected in each marsh and information on grain size foraminifera shell contents and stable carbon isotopes was obtained along with an age model using 210 pb 137 cs and 14 c core data combined with historical maps give evidence of a typical estuarine backfilling part of the holocene regressive parasequence including an intertidal mudflat at the base and a backshore environment at the top despite the absence of grain size anomalies marine flood related sedimentation in the backshore area of both marshes is identified by a mixture of marine and terrestrial features including marine fauna vegetation debris and variation in the 13 c signature of the organic fraction very low sedimentation rates between flood events and or bioturbation prevents the identification of individual episodic marine floods in the sediment succession comparison of the two sedimentary successions shows that the foraminifera deposited by marine submersions are of two different types foraminifera are monospecific and originate from the upper tidal mudflat in the sheltered marsh whereas in the backshore marsh located in a wave exposed environment they show higher diversity and originate from both shallow and deeper water marine environments this study shows that wave exposure can control the faunal content of marine flood sediment records in coastal marshes

microbial generation of economic accumulations of methane within a shallow organic rich shale although methane of bacterial origin is ubiquitous in marine and freshwater sediments economic accumulations of bacterial gases occur mainly at depths of several kilometres in tertiary basins that had high sedimentation rates1 2 here we present an integration of geochemical and isotopic data from gas and water extracted from the upper devonian antrim shale along the northern margin of the michigan basin which demonstrates that significant volumes of bacterial gas have been generated in organic rich shales at depths of less than 600 metres the antrim shale is mainly a self sourced reservoir in contrast to conventional gas deposits that have migrated from a source to a reservoir and has become one of the most actively exploited gas reservoirs3 in the united states the gas forming processes operating at shallow depths in the antrim shale are not unique4 and an understanding of these processes should lead to the identification and development of other economic non conventional gas deposits around the world

calibration of radiocarbon ages and the interpretation of paleoenvironmental records abstract calibration of the radiocarbon timescale of paleoecological records is essential if they are to be explained correctly in terms of their governing ecological or climatological controls the differences between calendar ages and radiocarbon ages that arise from variations in 14c production through time can distort the chronologies of individual records and the interpretations based on them misleading impressions of synchrony or diachrony of events among multiple records can result and estimates of the apparent duration of episodes and rates of sedimentation and local population changes can be biased displays of the temporal patterns of migration or extinction may also be affected spurious correlations may arise between records with radiocarbon controlled chronologies and time series of potential controls that are expressed on a calendar time scale support for particular explanations of features in a paleoecological record may vary depending on whether radiocarbon ages are calibrated or not this situation is illustrated using the eastern beringian populus subzone as an example when the radiocarbon ages that control the timing of the populus subzone are calibrated the contemporaneous decrease in ice volume and increase in summer insolation are implicated as the ultimate controls of the occurrence of the subzone

impact of particle transfer on flow properties of crushed mudstones karst collapse pillar kcp is widespread in north china coalfields where coal extraction above the ordovician limestone aquifer is threatened by the abundant supply of water and a very high hydraulic pressure kcp is composed of rock skeleton and fine fillings which can be transferred under the effect of water flow thus kcp usually functions as a channel for groundwater inrush in order to investigate the mechanism of mining induced groundwater inrush of kcp which was caused by fine fillings transfer a self designed particle transfer permeability testing system was used to test the crushed mudstones flow properties which included fine filling particle transfer rate porosity increase rate and permeability under the conditions of varying pore pressure particle size mixture and compaction level initial porosity the tests indicate fine fillings transfer is the essential reason for mining induced groundwater inrush flow instability of kcp the flow properties changeability during fine particle transfer could be divided into four stages i e initial flow stage flow inrush stage continued particle flow stage and stable flow stage and flow inrush stage which is the key point to cause water inrush due to the crushing of edges and corners and the adjustment of the structure the fluctuation of permeability time relationship mainly distributed in the first two stages which make a change to flow channel moreover with the increasing of pore pressure particle size mixture and initial porosity the water inrush time and stable seepage time decreased more rapidly the fine fillings porosity and permeability increased gradually the efficiency criteria analysis between measurement and calculation permeability shows an empirical equation can fit the relationship between porosity and permeability well and not all of the pore structures were in flow this means there was a part of pores that were invalid but the effective porosity in flow can be treated as calculation value approximately

tracking hurricane generated storm surge with washover fan stratigraphy we use the stratigraphy preserved in a washover fan to reconstruct the timing or emplacement and environmental conditions along the matagorda peninsula texas during hurricane ike in 2008 washover fan stratigraphy preserves a topset foreset break tfb that rises 0 42 m in elevation as the fan built landward we constrain overwash flow depths to 0 1 0 32 m through deposit sedimentology and tie the rising trajectory of the tfb to rising storm surge water levels measured in the back barrier bay 0 03 m h 1 as the hurricane approached the coast this relation allows us to estimate that the fan took 0 52 0 90 days to build and was finished building before the storm surge peaked this is 15 25 of the 3 5 days of hurricane induced storm surge near the site we show how washover stratigraphy can be used to constrain the timing and amount of sediment redistribution on a coast associated with a hurricane information that is necessary to test and or calibrate existing numerical models that predict shoreline change during hurricanes

paleotemperatures and paleofluids recorded in fluid inclusions from calcite veins from the northern flank of the ponta grossa dyke swarm implications for hydrocarbon generation and migration in the parana basin abstract the parana basin southern brazil has an atypical thermal and fluid history due to the occurrence of an episodic continental flood volcanism during the early cretaceous so far there are few data about the influence of this volcanic event on the paleotemperatures and paleofluids of the parana basin sedimentary rocks the teresina formation in the northern flank of the ponta grossa dyke swarm hosts high concentration of subsurface igneous rock bodies sills and dykes besides its covering by a hundreds meter thick volcanic rock cap in this study we used fluid inclusion analysis performed in horizontal and vertical calcite veins from the teresina formation and from a late cretaceous basic dyke to estimate paleotemperatures and to characterize the composition of diagenetic paleofluids homogenization temperatures of requilibrated fluid inclusions show that the teresina formation reached temperatures above 200 c horizontal parallel bedding calcite veins from the teresina formation record low to high salinity 2 26 wt nacl eq aqueous paleofluids the prevalence of high salinity fluid inclusions associated with light hydrocarbon fluid inclusions indicates deep buried fluids fluid inclusions in vertical calcite vein from basic dyke comprise only low salinity aqueous fluids 0 3 wt eq nacl interpreted as dominated by meteoric water the recorded paleotemperatures are attributed to the heating by the parana volcanic event during the early cretaceous with the thermal effect of the volcanic rock cap surpassing the effect of nearby sills and dykes estimated paleotemperatures higher than 200 c would allow the generation of light liquid and gaseous hydrocarbons overpressured compartments in the teresina formation allowed the expulsion of buried pore fluids high salinity aqueous fluids and hydrocarbons to fracture systems where they mixed with meteoric water the input of meteoric water through fracture systems connected with the surface favored hydrocarbons degradation in the early stages of source rock maturation during the early cretaceous

stalagmite stable isotope record of recent tropical cyclone events we present a 23 yr stalagmite record 1977 2000 of oxygen isotope variation associated with 11 tropical cyclones tcs from actun tunichil muknal cave in central belize high resolution microsampling yielded a record of monthly to weekly temporal resolution that contains abrupt decreases negative excursions in calcite 18 o values that correspond with recent tc rain events nearby a logistic discriminant model reliably identifi ed tc proxy signals using the measurable parameters 18 o and 13 c values and single point changes in 18 o value the logistic model cor rectly identifi ed 80 of excursions as tc events and incorrectly classifi ed only 1 of nearly 1200 nonstorm sampling points in addition to enabling high resolution tc frequency reconstruction this geologic proxy also provides information about the intensity of individual tcs a multiple regression predicted tc intensity r 2 0 465 p 0 034 using sampling frequency and excursion amplitude consistent with previous low resolution studies we found that the decadal average 18 o value was lower during the 1990s when several tcs produced rainfall in the area but higher during the 1980s when only one tc struck longer accurately dated high resolution speleo them stable isotope records may be a useful new tool for paleotempestology to clarify associa tions between highly variable tc activity and the dynamic range of quaternary climate

proxy records of holocene storm events in coastal barrier systems storm wave induced markers abstract extreme storm events in the coastal zone are one of the main forcing agents of short term coastal system behavior as such storms represent a major threat to human activities concentrated along the coasts worldwide in order to better understand the frequency of extreme events like storms climate science must rely on longer time records than the century scale records of instrumental weather data proxy records of storm wave or storm wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia this review provides a detailed state of the art compilation of the proxies available from coastal barrier systems to reconstruct holocene storm chronologies paleotempestology the present paper aims i to describe the erosional and depositional processes caused by storm wave action in barrier and back barrier systems i e beach ridges storm scarps and washover deposits ii to understand how storm records can be extracted from barrier and back barrier sedimentary bodies using stratigraphical sedimentological micro paleontological and geochemical proxies and iii to show how to obtain chronological control on past storm events recorded in the sedimentary successions the challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm chronologies using these various proxies are discussed and future research prospects are outlined