a simple model of gas production from hydrofractured horizontal wells in shales abstract assessing the production potential of shale gas can be assisted by constructing a simple physics based model for the productivity of individual wells we adopt the simplest plausible physical model one dimensional pressure diffusion from a cuboid region with the effective area of hydrofractures as base and the length of horizontal well as height we formulate a nonlinear initial boundary value problem for transient flow of real gas that may sorb on the rock and solve it numerically in principle solutions of this problem depend on several parameters but in practice within a given gas field all but two can be fixed at typical values providing a nearly universal curve for which only the appropriate scales of time in production and cumulative production need to be determined for each well the scaling curve has the property that production rate declines as one over the square root of time until the well starts to be pressure depleted and later it declines exponentially we show that this simple model provides a surprisingly accurate description of gas extraction from 8305 horizontal wells in the united states oldest shale play the barnett shale good agreement exists with the scaling theory for 2133 horizontal wells in which production started to decline exponentially in less than 10 yr we provide upper and lower bounds on the time in production and original gas in place

initial observations of lunar impact melts and ejecta flows with the mini rf radar 1 the mini rf radar on the lunar reconnaissance orbiter spacecraft has revealed a great variety of crater ejecta flow and impact melt deposits some of which were not observed in prior radar imaging the craters tycho and glushko have long melt flows that exhibit variations in radar backscatter and circular polarization ratio along the flow comparison with optical imaging reveals that these changes are caused by features commonly seen in terrestrial lava flows such as rafted plates pressure ridges and ponding small 20 km sized craters also show a large variety of deposits including melt flows and ponds two craters have flow features that may be ejecta flows caused by entrained debris flowing across the surface rather than by melted rock the circular polarization ratios cprs of the impact melt flows are typically very high even ponded areas have cpr values between 0 7 and 1 0 this high cpr suggests that deposits that appear smooth in optical imagery may be rough at centimeter and decimeter scales in some places ponds and flows are visible with no easily discernable source crater these melt deposits may have come from oblique impacts that are capable of ejecting melted material farther downrange they may also be associated with older nearby craters that no longer have a radar bright proximal ejecta blanket the observed morphology of the lunar crater flows has implications for similar features observed on venus in particular changes in backscatter along many of the ejecta flows are probably caused by features typical of lava flows

lead mobilization during tectonic reactivation of the western baltic shield abstract lead isotope data from sulfide deposits of the western part of the baltic shield define mixing lines in the 206 pb 204 pb 207 pb 204 pb diagram lead from two types of sulfide deposits have been investigated 1 1 exhalative and volcanogenic deposits that are syngenetic with their host rocks 2 2 vein deposits the syngenetic deposits locally show a very wide range of lead isotopic compositions that reflect a variable addition of highly radiogenic lead while the vein deposits although they have radiogenic lead isotopic compositions exhibit only limited isotopic variations in different provinces of the shield both types of deposits fall on the same lead mixing array the slope of the lead mixing lines varies as a function of the age of basement rocks and the age of the tectonic event which produced the lead mobilization and therefore relates the source rock age with the age of lead mobilization calculated mixing ages fall into several short time periods that correspond either to orogenic events or to major phases of continental rifting the orogenic events are the ca 360 430 ma caledonian ca 900 1100 ma sveconorwegian and the ca 1800 1900 ma svecofennian orogenic cycles the rifting events correspond to the formation of the ca 280 ma oslo rift and the ordovician ca 450 ma graben system in the area of the present gulf of bothnia each mixing age indicates that lead was mobilized probably as a consequence of mild thermal disturbances and that the crust was permeable to lead migration the data show that the geographic distribution of sulfide deposits with highly radiogenic lead isotopic compositions coincides with old graben systems orogenic belts and orogenic forelands on the baltic shield the ages of vein deposits and their geographic distribution demonstrate multiple tectonic reactivation of the interior of the baltic shield in response to orogenic events at its margin

pb isotopes in surficial pelagic sediments from the north atlantic we measured pb isotopic composition and concentration in sediment samples close to the sea water interface in 6 box cores from the ne atlantic 2 box cores from the sargasso sea and one from the us continental shelf the anthropogenic pb input to marine sediments due to the increase of pb contamination over the ocean during the last century can be identified in all these cores in the eastern part of the atlantic i e in regions under aeolian influence from europe pb pollution can be recognized using its distinctive unradiogenic composition clearly different from the upper crustal values commonly found in pre holocene sediments in contrast pb pollution in regions influenced by north american sources can be identified only in detailed concentration profiles because the american pb pollution has an isotopic composition much closer to that of the natural detrital pb input coming from weathering of the continental crust pb excess inventories are in good agreement with fluxes estimated from sedimenttrap data and with the time record of pb contamination increase given by analyses in coral growth bands inventories of pb contamination to the sediments of the mud patch american shelf are tenfold higher 84 g cm2 than those to hatteras and bermuda abyssal plains 4 3 and 2 8 g cm2

basinal brines and groundwaters as possible metal carriers in the formation of sandstone hosted lead zinc deposits features of the two best documented worldclass sandstone hosted pb zn deposits laisvall sweden yava nova scotia canada and a few similar but smaller deposits se missouri quebec appalachians are compared with the purpose of contributing to the debate on the problem of the aqueous medium of metal transport basinal brines or groundwaters for the dolostone sandstone hosted deposits in se missouri it is concluded that basinal brines formed this medium in both host rocks the paleotopographic control of these missouri deposits is pronounced and leads to the conclusion that such control is insufficient evidence to establish the groundwater hypothesis for the yava deposit in the quebec appalachian deposits basinal brines expelled tectonically were the most likely metal carriers these deposits constitute an ore type that differs from other known sandstone hosted lead deposits

geochemical constraints on the origin and volume of gas in the new albany shale devonian mississippian eastern illinois basin this study involved analyses of kerogen petrography gas desorption geochemistry microporosity and mesoporosity of the new albany shale devonian mississippian in the eastern part of the illinois basin specifically detailed core analysis from two locations one in owen county indiana and one in pike county indiana has been conducted the gas content in the locations studied was primarily dependent on total organic carbon content and the micropore volume of the shales gas origin was assessed using stable isotope geochemistry measured and modeled vitrinite reflectance values were compared depth of burial and formation water salinity dictated different dominant origins of the gas in place in the two locations studied in detail the shallower owen county location 415 433 m 1362 1421 ft deep contained significant additions of microbial methane whereas the pike county location 832 860 m 2730 2822 ft deep was characterized exclusively by thermogenic gas despite differences in the gas origin the total gas in both locations was similar reaching up to 2 1 cm3 g 66 scf ton lower thermogenic gas content in the shallower location lower maturity and higher loss of gas related to uplift and leakage via relaxed fractures was compensated for by the additional generation of microbial methane which was stimulated by an influx of glacial melt water inducing brine dilution and microbial inoculation the characteristics of the shale of the maquoketa group ordovician in the pike county location are briefly discussed to provide a comparison to the new albany shale

experimental evaluation of mixed fluid reactions between supercritical carbon dioxide and nacl brine relevance to the integrity of a geologic carbon repository abstract the reactive behavior of a mixed fluid supercritical co2 and brine under physical chemical conditions relevant to geologic storage and sequestration in a carbon repository is largely unknown experiments were conducted in a flexible cell hydrothermal apparatus to evaluate fluid rock aquifer plus aquitard reactions that may adversely impact the integrity of the repository a 5 5 molal nacl brine rock system was held at 200 c and 200 bars 20 mpa for 32 days 772 h to approach steady state then injected with co2 and allowed to react for an additional 45 days 1079 h in a separate experiment at 200 c and 200 bars the system was allowed to react for 77 days 1845 h without injection of co2 corroded magnesite and euhedral siderite crystallized in a paragenetic sequence after co2 injection nucleation and growth of siderite on shale suggests the aquitard is a reactive component in the system changes in elemental abundances in the brine following addition of co2 include ph decrease and depletion of sodium due to accelerated growth of analcime a ph increase follows pressure and temperature decrease and loss of saturated co2 from acidic brine silica concentrations and dissolution rates are enhanced and silica precipitation inhibited in the acidic brine geochemical reactions in a carbon repository extend beyond ph decrease and carbonate mineral precipitation rock dominated reaction systems yield to acid dominated and related reactions controlled by mixed fluid equilibria i e a fluid dominated system escape of co2 or migration of brine from the repository into overlying aquifers may cause silica super saturation and increased alkalinity due to mixed fluid phase equilibria these geochemical changes could be monitored in aquifers as indicators of repository integrity return of silica super saturated brine to a rock dominated reaction system buffered to neutral ph conditions may enhance precipitation of quartz chalcedony or amorphous silica in addition to the potential effects beneficial or deleterious that silica super saturation and precipitation may hold for repository performance an understanding of the effects of multi phase equilibrium relationships between supercritical co2 and dissolved silica in aquifer brine systems also raises new questions for a variety of geologic systems multi phase fluid equilibria may for example account for quartz cements in some sedimentary basin sandstones and quartz vein mineralization in some ore districts

modeling polarimetric radar scattering from the lunar surface study on the effect of physical properties of the regolith layer 1 a theoretical model for radar scattering from the lunar regolith using the vector radiative transfer theory for random media has been developed in order to aid in the interpretation of mini sar data from the chandrayaan 1 and lunar reconnaissance orbiter missions the lunar regolith is represented as a homogeneous fine grained layer with rough upper and lower parallel interfaces that possesses embedded inclusions with a different dielectric constant our model considers five scattering mechanisms in the regolith layer diffuse scattering from both the surface and subsurface volume scattering from buried inclusions and the interactions of scattering between buried inclusions and the rough interfaces both the lunar surface and subsurface multiple scattering between buried inclusions and coherent backscatter opposite effect are not considered in the current model the modeled radar scattering coefficients are validated using numerical finite difference time domain simulations and are compared with incident angle averaged earth based radar observations of the moon both polarized and depolarized radar backscattering coefficients and the circular polarization ratio cpr are calculated as a function of incidence angle regolith thickness surface and subsurface roughness surface slope abundance and shape of buried rocks and the feo tio2 content of the regolith simulation results show that the polarized opposite sense radar echo strength at s and x bands is mostly dominated by scattering from the rough surface and buried rocks while the depolarized same sense radar echo strength is dominated by scattering from buried rocks or ice inclusions finally to explore the expected polarimetric signature of ice in the polar permanently shadowed areas four parametric regolith models are considered and the possibility of detecting diffuse ice inclusions by the cpr is addressed our study suggests that detection of ice inclusions at the lunar poles using solely the cpr will be difficult given the small dielectric contrast between the regolith and ice

early diagenesis and isotopic composition of lead in lake laisan northern sweden water column dissolved suspended phase sediment traps and sediment data pore water solid phase sediment were combined with stable pb and pb 210 isotope data to trace the early diagenetic behaviour and geochemical cycling of pb in lake laisan a lake which has received large quantities of anthropogenic pb since the early 1940s early diagenetic remobilisation of pb is indicated by a subsurface pore water pb maximum 120 mug 1 1 in the oxic surface layer of the sediment where the solid phase pb concentration is 3400 4600 mug g 1 the remobilisation of pb appears to be caused by a ph controlled desorption of pb from solid phase sediment which is consistent with a model describing surface complexation of pb ii on hydrous goethite surfaces the diffusive pb flux from the subsurface pore water maximum towards the sediment surface 36 mug cm 2 year 1 exceeds the depositional pb flux 8 6 mug cm 2 year 1 by approximately a factor of four indicating that pb is highly mobile in the sediment stable pb isotope data and a mass balance calculation suggest that pb diffusing upwards is to a large extent trapped in the surface sediment lead that may diffuse into the slightly alkaline lake water appears to be efficiently sorbed to suspended particulate matter resulting in low dissolved pb concentrations in the water column 0 040 0 046 mug 1 1 sorption of pb to suspended particulate matter is consistent with the elevated suspended particulate pb concentrations in the hypolimnion 3800 4000 mug g 1 and the fact that the stable pb isotopic compositions of suspended matter and pore water are similar less

tectonic and stratigraphic controls of hydrocarbon systems in the ordos basin a multicycle cratonic basin in central china the ordos basin is the oldest and still an important hydrocarbon province in central china it is a typical cratonic basin developed on the archean granulites and lower proterozoic greenschists of the north china block the development of the ordos basin during the paleozoic mesozoic can be divided into three evolutionary stages cambrian early ordovician cratonic basin with divergent margins middle ordovician middle triassic cratonic basin with convergent margins and late triassic early cretaceous intraplate remnant cratonic basin two hydrocarbon systems are present in the basin the paleozoic gas and mesozoic oil systems in the paleozoic gas system the lower ordovician marine carbonates and pennsylvanian lower permian coal measures serve as source rocks the lower ordovician karst modified dolomites and pennsylvanian bauxitic mudstones form a significant reservoir seal association and the pennsylvanian lower permian deltaic sandstones and upper permian lacustrine mudstones form another effective reservoir seal association in the mesozoic oil system the upper triassic lacustrine mudstones are mature source rocks the upper triassic deltaic sandstones and overlying shallow lacustrine and swamp mudstones form a reservoir seal association and the lower jurassic fluvial sandstones and overlying shallow lacustrine and swamp mudstones form another reservoir seal association in both hydrocarbon systems the stratigraphic variations provide the principal traps the ordos basin is characterized by a stable tectonic setting that controlled the distribution of depositional systems and the development of erosional surfaces and ultimately governed the distribution of oil and gas fields and trap types

initial results for the north pole of the moon from mini sar chandrayaan 1 mission 1 we present new polarimetric radar data for the surface of the north pole of the moon acquired with the mini sar experiment onboard india s chandrayaan 1 spacecraft between mid february and mid april 2009 mini sar mapped more than 95 of the areas polewards of 80 latitude at a resolution of 150 meters the north polar region displays backscatter properties typical for the moon with circular polarization ratio cpr values in the range of 0 1 0 3 increasing to over 1 0 for young primary impact craters these higher cpr values likely reflect surface roughness associated with these fresh features in contrast some craters in this region show elevated cpr in their interiors but not exterior to their rims almost all of these features are in permanent sun shadow and correlate with proposed locations of polar ice modeled on the basis of lunar prospector neutron data these relations are consistent with deposits of water ice in these craters

earth based 12 6 cm wavelength radar mapping of the moon new views of impact melt distribution and mare physical properties abstract we present results of a campaign to map much of the moon s near side using the 12 6 cm radar transmitter at arecibo observatory and receivers at the green bank telescope these data have a single look spatial resolution of about 40 m with final maps averaged to an 80 m four look product to reduce image speckle focused processing is used to obtain this high spatial resolution over the entire region illuminated by the arecibo beam the transmitted signal is circularly polarized and we receive reflections in both senses of circular polarization measurements of receiver thermal noise during periods with no lunar echoes allow well calibrated estimates of the circular polarization ratio cpr and the four element stokes vector radiometric calibration to values of the backscatter coefficient is ongoing radar backscatter data for the moon provide information on regolith dielectric and physical properties with particular sensitivity to ilmenite content and surface or buried rocks with diameter of about one tenth the radar wavelength and larger average 12 6 cm circular polarization ratio cpr values for low to moderate tio 2 mare basalt deposits are similar to those of rough terrestrial lava flows we attribute these high values to abundant few centimeter diameter rocks from small impacts and a significant component of subsurface volume scattering an outflow deposit inferred to be impact melt from glushko crater has cpr values near unity at 12 6 cm and 70 cm wavelengths and thus a very rugged near surface structure at the decimeter to meter scale this deposit does not show radar brightness variations consistent with levees or channels and appears to nearly overtop a massif suggesting very rapid emplacement deposits of similar morphology and or radar brightness are noted for craters such as pythagoras rutherfurd theophilus and aristillus images of the north pole show that despite recording the deposition of orientale material byrd and peary craters do not have dense patterns of radar bright ejecta from small craters on their floors such patterns in amundsen crater near the south pole were interpreted as diagnostic of abundant impact melt so the fraction of orientale derived melt in the north polar smooth plains 1000 km farther from the basin center is inferred to be much lower

hydrofracturing and episodic fluid flow in shale rich basins a numerical study low permeability sedimentary rocks commonly are fractured direct examination of exposed rock faces and drill cores shows evidence of hydrofracturing the mechanism for hydrofracturing its effects on fluid migration and its dependence on sediment permeability sedimentation rate and sedimentary sequences have not been explored in this study we carry out systematic numerical experiments to study the compaction induced hydrofracturing we show that the compaction induced hydrofracturing commonly may occur in shale rich basins and in sand shale sequences the frequency of such hydrofracturing depends on sediment permeability sedimentation rate and sedimentary sequence an important result is that compaction induced hydrofracturing may occur at relatively shallow depths in shale rich basins but it may mobilize enhanced fluid flow throughout the sedimentary basin over 60 of the total compaction induced fluid flow in the basin may be expelled during hydrofracturing we test the model against field data from the yinggehai basin of the south china margin where abundant hydrofractures in the uppermost quaternary marine mud have been recently detected by seismic imaging we suggest that the compaction induced hydrofracturing may mobilize fluid flow at great depths and affect hydrocarbon migration in shale rich basins

metamorphosed proterozoic zn pb ag mineralization in the foster river area northern saskatchewan canada metamorphosed zn pb occurrences fable lake george sito south sito southwest sito west sito east robyn lake and mackie lake with high zn pb ratios occur in the foster river area northern saskatchewan on the southeast margin of the paleoproterozoic wollaston domain the sito east prospect the largest of these occurrences contains 50 000 tonnes of 4 5 zn with one drill intercept containing 11 m of 4 2 zn and 0 6 pb most prospects are hosted in a thin areally extensive metaquartzite within a thick sequence of metasiltstones and metaquartzites in the middle of the paleoproterozoic wollaston group occurrences in metaquartzites and metaarkoses which locally contain gahnite spessartine and or graphite are spatially associated with metaexhalites iron formation and quartz garnetite and strata bound metamorphosed hydrothermal alteration zones nodular sillimanite rock post archean australian shale normalized rare earth element ree patterns of all three rock types are characterized by light ree enrichment positive ce anomalies neutral to strongly negative eu anomalies and heavy ree depletion consistent with an environment of deposition distinguished by a high 30 wt continental detrital component and formation from or interaction with low temperature 250 c near neutral ph and high fo2 fluids sulfur isotope compositions of sulfides at foster river are highly enriched in 34s 34s 26 2 38 1 n 20 and resulted from microbial reduction of partially reduced seawater sulfate in a restricted basin the spatial association of spessartine and gahnite bearing lithologies and silicate facies iron formation with paleoproterozoic base metal sulfides in a psammopelitic host sequence implies similarities between sulfide mineralization in the foster river area and broken hill type pb zn ag deposits however the markedly enriched 34ssulfide compositions low pb pb zn and ag pb zn ag ratios low ag contents and apparent absence of metavolcanic and metavolcaniclastic rocks in the dominantly clastic rock sequence hosting the sulfides in the foster river area suggest that these occurrences are part of a metamorphosed sedimentary exhalative system with broken hill type affinities similar to that associated with the formation of the gamsberg zn south africa kanmantoo group pb zn south australia and sullivan pb zn canada deposits

isotopic composition of phanerozoic ore leads from the swedish segment of the fennoscandian shield 95 analyses of ore lead isotope ratios from 23 phanerozoic ore deposits from the swedish segment of the fennoscandian shield form a marked linear trend on a 207pb 204pb versus 206pb 204pb diagram the line may be interpreted in a two stage model the lead being derived from 1 8 0 15 ga old svecokarelian basement and mineralization occurring at 0 4 0 15 ga the initial composition of the svecokarelian rock lead was similar to the lead in early proterozoic volcanogenic sulfide ores in sweden the large spread in the isotope ratios was caused by a combination of selective leaching of different minerals in the source rocks mixing with less radiogenic caledonian lead and local or regional variations in the u th and pb contents of the basement as a consequence conventional methods of identifying source rocks from lead isotopic data e g mu values th u ratios may not be directly applicable phanerozoic ore lead development in the swedish section of the fennoscandian shield was ensialic that is the ore lead was almost entirely derived from the precambrian basement although this basement does not appear to be anomalously enriched in pb no juvenile or mantle lead was apparently contributed to this section of the crust after the precambrian except for that mechanically transported onto the western edge of the shield by the caledonian nappes however some of europe s largest lead deposits are included in these swedish phanerozoic mineralizations suggesting that it was the nature of the processes involved rather than the richness of the source that determined their formation

control of reactivated proterozoic basement structures on sandstone hosted pb zn deposits along the caledonian front sweden evidence from airborne magnetic data structural analysis and ore grade modeling strata bound nonstratiform epigenetic galena sphalerite cement mineralization in ediacaran cambrian sandstone including the previously mined deposits at laisvall and vassbo occurs along the eas

highly silicic compositions on the moon using data from the diviner lunar radiometer experiment we show that four regions of the moon previously described as red spots exhibit mid infrared spectra best explained by quartz silica rich glass or alkali feldspar these lithologies are consistent with evolved rocks similar to lunar granites in the apollo samples the spectral character of these spots is distinct from surrounding mare and highlands material and from regions composed of pure plagioclase feldspar the variety of landforms associated with the silicic spectral character suggests that both extrusive and intrusive silicic magmatism occurred on the moon basaltic underplating is the preferred mechanism for silicic magma generation leading to the formation of extrusive landforms this mechanism or silicate liquid immiscibility could lead to the formation of intrusive bodies

geologic analyses of shuttle imaging radar sir b data of kilauea volcano hawaii analyses of imaging radar data of volcanic terranes on earth and venus have emphasized the need for a clearer understanding of how these data can be most effectively used to accomplish important volcanological goals including the interpretation of eruptive styles and the characterization of the geologic history of volcanic centers the second shuttle imaging radar experiment sir b obtained two digital images over the summit caldera and the southwest rift zone of kilauea volcano in 1984 our geologic analyses of these images indicate that sir b data are particularly useful for delineating the distribution and surface textural variations of a9a lava flows for mapping large scale topographic features with radar facing slopes and for identifying an areally extensive pyroclastic deposit analyses of the sir b data of kilauea however do not permit unambiguous identification of landforms such as pahoehoe lava flows cinder cones and fissures although separation of low return units such as pahoehoe lava flows and adjacent pyroclastic ash is not greatly improved using standard image enhancement techniques the texture analysis technique applied here did facilitate discrimination of such smooth surfaced volcanic deposits although analyses of the sir b data permit a generally accurate interpretation of the eruptive history of kilauea the inability to distinguish low return pahoehoe flows results in misinterpretation of several aspects of kilauea volcanism suggesting that caution should be exercised in the interpretation of sar data of volcanic terranes

noble gas and halogen evidence for the origin of scandinavian sandstone hosted pb zn deposits abstract fluid origins in the sandstone hosted pb zn class of ore deposit have been investigated in three deposits from scandinavia laisvall vassbo and osen the deposits studied are hosted by autochthonous cambrian sandstones that preserve a near original structural relationship to the underlying precambrian basement enabling the role of basement interaction to be assessed mineral samples have been collected from across the paragenetic sequence sphalerite galena pyrite fluorite and barite of impregnation and related joint hosted mineralization fluid inclusion halogen cl br and i and noble gas isotope 40 ar 36 ar 84 kr compositions were determined simultaneously by noble gas mass spectrometry of irradiated sample splits complementary he isotope analyses are obtained from nonirradiated splits of the same samples 3 he 4 he values at laisvall and osen are highly radiogenic 0 02 ra and the 4 he 40 ar ratio extends to values greater than the crustal production value of 5 characteristic of low temperature crustal fluids at vassbo a slightly elevated 3 he 4 he ratio of 0 1 0 3 ra is compatible with a very minor mantle component 1 4 suggesting a distal source for the basinal brine dominated fluid br cl molar ratios 3 2 8 2 10 3 are greater than the present seawater value of 1 54 10 3 and correspond with i cl molar ratios in the range 64 1600 10 6 the upper limits of both the i cl and br cl values are amongst the highest measured in crustal fluids together the data indicate acquisition of salinity by the evaporation of seawater beyond the point of halite saturation and subsequent fluid interaction with i rich organic matter in the subsurface the data are compatible with the independent transport of sulfate and sulfide and indicate that fluids responsible for joint hosted mineralization were distinct to those responsible for impregnation mineralization all three deposits preserve fluids with 40 ar 36 ar in the range of 6 000 10 000 and fluid inclusion 40 ar concentrations of 0 02 0 05 cm 3 cm 3 fluid inclusion 4 he concentrations are also extremely elevated with maximum values of 0 1 cm 3 cm 3 in laisvall fluorite and sphalerite the high 40 ar 36 ar values together with the high 4 he and 40 ar concentrations result from a very long premineralization crustal residence time on the order of 100 200 ma together the noble gas and halogen data are compatible with a caledonian mineralization event 425 ma caused by mixing of two or more long lived hydrothermal basinal brines and pore fluids at the sites of mineralization the data suggest negligible recharge of the basinal brines by meteoric water and indicate extensive fluid basement interaction before mineralization the similar noble gas composition of each deposit suggests that similar processes operated at all three deposits and favors a single pass fluid flow model for mineralization

rugged lava flows on the moon revealed by earth based radar 1 basaltic volcanism is widespread on the lunar nearside and returned samples suggest that the mare forming magmas had low viscosity that led to primarily sheet like deposits new 70 cm wavelength radar observations that probe several meters beneath the lunar surface reveal differences in mare backscatter properties not explained by age or compositional variations we interpret areas of high backscatter and high circular polarization ratio in maria serenitatis imbrium and crisium as having an enhanced abundance of decimeter scale subsurface rocks relative to typical mare forming flows the 3 5 b y survival of these differences implies an initial platy blocky or ridged lava flow surface layer with thickness of at least 3 5 m such rugged morphology might arise from episodic changes in magma effusion rate as observed for disrupted flood basalt surfaces on the earth and mars very high flow velocities or increased viscosity due to a number of factors significant information on lunar mare eruption conditions may thus be obtained from long wavelength radar probing of the shallow subsurface

the mairan domes silicic volcanic constructs on the moon 1 the mairan domes are four features located in northern oceanus procellarum at 312 3e 41 4n on the moon high resolution visible imagery visible to mid ir spectra and lunar prospector th abundance data all indicate that these four domes have a composition that is consistent with derivation from a si rich highly evolved magma

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

compositional variability of the marius hills volcanic complex from the moon mineralogy mapper m3 1 using the moon mineralogy mapper m3 we examine the marius hills volcanic complex for the first time from 0 46 to 2 97 m the integrated band depth at 1 m separates the mare basalts on the plateau in two units 1 a strong 1 m band unit of localized lava flows within the plateau that has similar olivine rich signatures to those of the nearby oceanus procellarum and 2 a weaker 1 m band unit that characterizes most of the basalts of the plateau which is interpreted as having a high calcium pyroxene signature domes and cones within the complex belong to the high calcium pyroxene plateau unit and are associated with the weakest 1 m band observed on the plateau this difference could be the result of higher silica content more opaque minerals and or a weaker olivine content of the magma finally the floor of marius crater has one of the strongest olivine rich signatures of the entire marius hills complex these compositional differences are indicative of the long and complex volcanic history of the region the first episode started before the emplacement of the surrounding basalts of the plateau and produced the high calcium pyroxene flows present on the plateau and their associated domes and cones the second episode occurred concurrently or slightly after the emplacement of the adjacent procellarum basalts and produced the olivine rich basalts seen within the plateau outside the plateau and in marius crater if the olivine content of the lava flows increases with time the olivine rich region on the floor of marius crater may represent one of the latest episodes of volcanism exposed on the marius hills complex

numerical simulation of long term storage of co2 in yanchang shale reservoir of the ordos basin in china abstract shale reservoirs have attracted increasing attention in recent years as a new and promising geological repository for carbon dioxide co 2 storage however their long term storage mechanism is unclear and the interactions between co 2 adsorption to shale and the co 2 water rock reactions have not been investigated a 2 d simplified reactive transport model is developed in this paper based on the properties of a shale reservoir in the ordos basin in china which has been identified as a promising location for shale gas production and co 2 storage the model is used to study the co 2 water rock reactions coupled with gas adsorption and to identify the long term trapping mechanisms of co 2 in shale gas results show that in short several decades to middle term hundreds of years co 2 storage in a shale reservoir 60 co 2 is trapped in the supercritical and adsorbed phases but in the long term thousands of years mineral trapping gradually plays a dominant role among other storage mechanisms the displacement of ch 4 with co 2 during injection is also analyzed results show that this process can be divided into two stages the pre displacement stage during which the adsorbed concentrations of both ch 4 and co 2 increase due to pressure build up but due to low concentration of co 2 displacement does not occur at this stage and the displacement stage during which the co 2 concentration is high enough to displace the ch 4 from the host rock also higher pressure facilitates the displacement of ch 4 by co 2 in this stage study of the interaction between gas adsorption and co 2 water rock reactions shows that by buffering the reservoir pressure during co 2 injection into the subsurface gas adsorption can impact the solubility trapping process so as to interfere with the co 2 water rock reactions furthermore this interference is intensified with reduction in co 2 concentration in the reservoir over time sensitivity analysis indicates that variations in the co 2 adsorption isotherm abundance of smectite and chlorite reaction rate and reactive surface area of smectite can significantly affect the co 2 storage by different trapping mechanisms the high co 2 adsorption capacity of shale is very beneficial for co 2 injection into a shale reservoir the amount of adsorbed co 2 is proportional to the co 2 adsorption isotherm while co 2 in other phases gas supercritical phase dissolved phase and mineral phase is inversely related to the co 2 adsorption isotherm smectite and chlorite are the key minerals that influence the co 2 water rock reactions in yanchang shale

lro observations of morphology and surface roughness of volcanic cones and lobate lava flows in the marius hills 1 the volcanic domes cones sinuous rilles and pyroclastic deposits of the marius hills region of the moon 13 4 n 304 6 e represent a significant episode of magmatic activity at or near the lunar surface that is still poorly understood comparisons between lroc nac block populations mini rf data and diviner derived rock abundances confirm that blocky lava flows comprise the domes of the marius hills 8 m features measured by diviner indicate that the domes are not rich in silica and are not significantly different than surrounding mare materials lroc observations indicate that some of the dome building lava flows originated directly from volcanic cones many of the cones are c shaped while others are irregularly shaped and local topography and lava eruptions affect cone shape in general the cones are morphologically similar to terrestrial cinder and lava cones and are composed of varying amounts of cinder spatter and lava many of the cones are found in local groupings or alignments the wide range of volcanic features from broad low domes to steep cones represents a range of variable eruption conditions complex morphologies and variable layering show that eruption conditions were variable over the plateau

linking of fractures in layered rocks implications for permeability abstract the permeability of many rocks including many reservoirs is mostly attributable to fractures that form interconnected clusters here we present the results of field studies and numerical models on the linkage of fractures using primarily fractures in carbonate rocks from the uk the numerical models focus on two fracture configurations five offset fractures in a 5 layer model and a single hydrofracture in a 3 layer model in some of the 3 layer models a weak open contact is added between the two topmost layers in the 5 layer models loading is by 5 mpa tensile stress whereas the 3 layer models the only loading is the internal fluid overpressure of 6 mpa in the hydrofracture itself located in the lowermost of the three layers for the 5 layer models tensile stresses occur between the nearby tips of the offset fracture pairs but these stresses are generally too low in the soft shale layers to initiate fractures the tensile stresses however commonly concentrate at the contacts between the shale and limestone layers and may therefore result in delamination debonding that is opening of the contacts by contrast the shear stresses between the nearby tips of the fracture pairs are often high enough to generate shear or mixed mode fractures that connect the nearby tips of the original offset fractures resulting in clusters that can conduct fluids for the 3 layer models the fracture induced tensile stresses in the uppermost layer are suppressed by a comparatively thick compliant shale layer and or the weak open contact thus no fracture formation is possible in that layer but at their contacts with the compliant layer the hydrofracture apertures increase thus a compliant layer may arrest the vertical hydrofracture propagation from its stiff host layer but at the same time increase its maximum aperture and encourage lateral fluid transport at the layer contact between the layers

lead mobilization during foreland metamorphism in orogenic belts examples from northern sweden the imbrication of the proterozoic basement during the caledonian orogeny was associated with fluid flow which caused locally low grade retrograde metamorphism of the basement and which introduced externally derived radiogenic lead 206pb 204pb 20 0 into permeable zones this radiogenic lead was leached from the proterozoic basement to the east of the present day caledonian front radiogenic lead is a pertinent geochemical tracer of the caledonian imbrication of the proterozoic basement since lithostratigraphic marker beds are absent and the distribution of the retrograde metamorphism also could reflect a proterozoic event

the relationship between radar scattering and surface roughness of lunar volcanic features lunar roughness measurements derived from the lunar orbiter laser altimeter are compared to 12 6 cm wavelength radar data collected by the miniature radio frequency instrument and 70 cm wavelength radar data collected by the arecibo observatory these data are compared to assess how surface and subsurface roughness are correlated and affected by parameters including age and composition at length scales between 0 1 and 100 m a range of features are analyzed including volcanic domes marius hills rumker hills gruithuisen and mairan domes mare imbrium serenitatis and oceanus procellarum pyroclastic dark mantle deposits sinus aestuum sulpicius gallus and mare vaporum and two young craters copernicus and tycho statistically significant positive correlations exist between topographic roughness and both p and s band circular polarization ratios the strongest correlation is observed at the longest length scales correlations weaken as length scales become less similar potentially due to distinct processes controlling surface modification roughness is not significantly correlated with local slope although the marius hills are compositionally distinct from the gruithuisen and mairan domes they are indistinguishable in roughness characteristics conversely the rumker hills mare and dark mantle deposits are smoother at the length scales examined possibly due to fine grained mantling of regolith or pyroclastic deposits the floor and ejecta of tycho are the roughest surfaces measured in this study while the floor and ejecta of copernicus overlap the roughness distribution of the volcanic features this study shows that many factors control the evolution of roughness over time on various length scales

lead isotopes as tracers of lead pollution from various sources an example from northern sweden abstract the surface sediments in the central bothnian bay are contaminated with anthropogenic pb preindustrial concentrations range from 9 to 43 ppm but the surface sediments contain up to 158 ppm pb possible sources of the pb pollution are anthropogenic atmospheric pb where the main pb source is combustion of gasoline and ore from the laisvall mine which is processed in the smelter ronnskars verken on the coast of bothnian bay because the pb isotope composition of these possible sources are known an attempt was made to trace the origin of the anthropogenic pb in bothnian bay by studying the pb isotope composition of sediments the results show unequivocally that laisvall pb is not the source of the pollution the enrichment of pb in surface sediments is caused by atmospheric deposition of pb additives from gasoline lead emitted from ronnskarsverken is deposited relatively close to the smelter and has not reached central bothnian bay in traceable amounts

lead isotopic evidence for the origin of 1 8 1 4 ga ores and granitoids in the southeastern part of the fennoscandian shield abstract new data for the lead isotopic composition of galena from ore deposits related to 1 8 1 4 ga granitoids in the southeastern part of the fennoscandian shield are presented and discussed together with earlier published information on granitoids and associated ore deposits two types of sulphide deposits genetically related to the granites can be recognized based on general metallogenetic features and isotopic composition granite hosted deposits including sn bearing greisen veins in rapakivi granites and peri intrusive deposits including contact metasomatic skarn deposits like pitkaranta and gruvasen in addition epigenetic deposits with a spatial but not a genetic link to the granites occur at various sites an important metallogenetic belt related to 1 7 1 5 ga granitoids can be followed in an east west direction across the shield from lake siljan in sweden to salmi at lake ladoga within this belt a major difference in metal derivation can be recognized ore deposits southwest of the raahe ladoga line i e in areas without archaean basement indicate metal derivation from remelted 1 9 ga svecofennian crust whereas ore deposits in areas underlain by archaean rock units indicate metal derivation from highly metamorphosed archaean sources

potential for enhanced gas recovery and co2 storage in the marcellus shale in the eastern united states abstract organic rich gas shales behave similarly to coal and desorb methane while preferentially adsorbing carbon dioxide co2 in addition to the adsorption of co2 on the surface of shale the fracture network and pore volume containing free non adsorbed methane is also expected to be available for co2 storage especially where previous hydraulic fracturing and subsequent production has enhanced injectivity co2 injection into organic rich gas shales could provide dual benefits of incremental recovery of methane and secure co2 storage this paper reports on research sponsored by the u s department of energy to assess factors influencing effective co2 storage capacity and injectivity in the marcellus shale in the eastern united states geological characterization was conducted which estimated total gas in place and theoretical maximum co2 storage capacity within the marcellus theoretical maximum co2 storage capacity assumes 100 of methane in place either as adsorbed or free gas is replaced by injected co2 detailed reservoir characterization was conducted to determine depth thickness total organic carbon effective porosity apparent gas saturation co2 and methane adsorption isotherms and permeability throughout the marcellus shale estimates of total gas in place and maximum co2 storage capacity are developed for the study area where depth to the marcellus exceeds 915 m 3000 ft estimated total theoretical maximum co2 storage capacity is 1 6 million tonnes per square kilometer mt km2 of which adsorbed co2 storage capacity is estimated to be 0 92 mt km2 detailed reservoir simulation was performed to develop a better understanding of the shale characteristics influencing potential enhanced gas recovery storage capacity and injectivity a reservoir model was developed based on these data and reservoir simulation was performed to determine the portion of the theoretical storage capacity that could be accessible simulated production results were compared to available production data to demonstrate that the reservoir models are representative of existing field conditions co2 injection rates are estimated via simulation to predict the incremental volume of methane produced the total volume of co2 to be potentially stored and the disposition of co2 in the reservoir over time typical gas recovery factors for gas shales range from 20 to 35 with an average factor of 25 for shale gas basins and formations that have a medium clay content moderate geologic complexity and average reservoir pressure and properties similar to the marcellus shale simulation results from this study indicate that at optimal spacing between the injection and production wells 7 incremental enhanced gas production due to co2 injection can be realized combining this with a 25 primary recovery efficiency gives a total recovery efficiency of 32 assuming this for the entire marcellus shale study area approximately 12 trillion cubic meters tm3 of methane is technically recoverable and would result in 55 billion tonnes gt of co2 storage capacity

acoustic emission monitoring of hydraulic fracturing laboratory experiment with supercritical and liquid co2 1 carbon dioxide co2 is often used for enhanced oil recovery in depleted petroleum reservoirs and its behavior in rock is also of interest in co2 capture and storage projects co2usually becomes supercritical sc co2 at depths greater than 1 000 m while it is liquid l co2 at low temperatures the viscosity of l co2is one order lower than that of normal liquid water and that of sc co2is much lower still to clarify fracture behavior induced with injection of the low viscosity fluids we conducted hydraulic fracturing experiments using 17 cm cubic granite blocks the ae sources with the sc and l co2injections tend to distribute in a larger area than those with water injection and furthermore sc co2tended to generate cracks extending more three dimensionally rather than along a flat plane than l co2 it was also found that the breakdown pressures for sc and l co2 injections are expected to be considerably lower than for water