mineral mapping and ore prospecting using landsat tm and hyperion data wushitala xinjiang northwestern china abstract the southern tianshan area situated in central asia is one of the most important gold belts identified by many world class superlarge and large gold deposits the wushitala area located in the eastern part of southern tianshan xinjiang china has a strong potential for gold and other metallic mineral deposits however no metallic mineral deposit or occurrence has been reported in detail for the wushitala area in the past apparently due to poor exploration this study attempts to map alteration zones and acquire ore prospecting targets in the wushitala area by integrating landsat tm and hyperion data with the aster spectral library mineral spectra the crosta technique and the anomaly overlaying selection method were combined to process four temporal landsat tm data acquired in the same season in different years so as to eliminate the random interference caused false anomalies of alteration minerals iron oxides and hydroxyl bearing minerals and carbonates while retaining the real anomalies the matched filtering method was applied on hyperion data for the detailed identification of hydrothermally altered minerals surrounding the granites in the north the results of hyperion data are spatially consistent with those of landsat tm data furthermore the results of hyperion data show that the alteration minerals associated with the potash feldspar granite are dominated by muscovite and goethite in our field campaign fourteen sites eleven acid intrusion related and three structure associated distributed throughout the study area were inspected all of which proved to be of geological genesis our study led to the discovery of three mineralization sites associated with acid intrusions and structures that were not previously documented due to the extensively distributed acid intrusions and structures along the southern tianshan belt several other gold iron copper mineralized locations could be found with more detailed investigations our mineral prospecting methodology proved effective in the study area and is hereby suggested for application in similar geological settings

introduction to special issue on geologic remote sensing abstract herein we provide an overview of science and technology involved in remote sensing and outlines some practical constraints in applications to geological problems we further summarize diagnostic spectral features of important geological material that can be detected using satellite and air borne remote sensing finally the papers contained in the special issue are briefly introduced

space time relation of post collisional granitic magmatism in santa catarina southern brazil u pb la mc icp ms zircon geochronology of coeval mafic felsic magmatism related to the major gercino shear zone abstract la mc icp ms u pb zircon dating was performed on syntectonic early post collisional granitic and associated mafic rocks that are intrusive in the brusque metamorphic complex and in the florianopolis batholith major tectonic domains separated by the neoproterozoic major gercino shear zone mgsz in south brazil the inferred ages of magmatic crystallization are consistent with field relationships and show that the syntectonic granites from both domains are similar with ages around 630 620 ma for high k calc alkaline metaluminous granites and ca 610 ma for slightly peraluminous granites although ca 650 ma inherited zircon components are identified in granites from both domains important contrasts on the crustal architecture in each domain are revealed by the patterns of zircon inheritance indicating different crustal sources for the granites in each domain the granites from the southern domain florianopolis batholith have essentially neoproterozoic 650 700 ma and 900 950 ma inheritance with a single 2 0 2 2 ga inherited age obtained in the peraluminous mariscal granite in the northern brusque metamorphic complex the metaluminous rio pequeno granite and associated mafic rocks have scarce inherited cores with ages around 1 65 ga whereas the slightly peraluminous serra dos macacos granite has abundant paleoproterozoic 1 8 2 2 ga and archean 2 9 3 4 ga inherited zircons our results are consistent with the hypothesis that the mgsz separates domains with distinct geologic evolution however the contemporaneity of 630 610 ma granitic magmatism with similar structural and geochemical patterns on both sides of this major shear zone indicates that these domains were already part of a single continental mass at 630 ma reinforcing the post collisional character of these granites

remote sensing and petroleum seepage a review and case study when reservoirs leak varying quantities of oil and gas migrate to the surface as macroseeps which are visible and microseeps which are invisible this review article describes the mechanisms of seepage and the resulting surface manifestations in relation to optical high resolution remote sensing data oil pools and tar deposits macroseeps often can be detected directly by remote sensing microseeps are more difficult to study using remote sensing but they give rise to vegetation stress and cause geochemical alterations in soil and rocks which can be studied indirectly using hyperspectral sensors an integrated methodology is presented to combine various geoscience and remote sensing datasets for seepage detection a combination of red edge modelling algorithms and spectral matching tools is identified that provides a validated technique for onshore microseepage detection these remote sensing tools are not only important for petroleum exploration but also have environmental implications because seeps emit greenhouse gases a statistical data integration approach was developed based on bayesian assumptions which can be used to integrate hyperspectral remote sensing data other satellite remote sensing data and ancillary field geological and geochemical datasets for modelling microseepage in a case study from the ventura basin santa barbara in southern california probe 1 data from the 1998 geosat group shoot are integrated with field and subsurface geological and geochemical data to predict possible sites of hydrocarbon microseepage

potential of sentinel 2 data for alteration extraction in coal bed methane reservoirs abstract this study illustrates the potential of alteration extraction in coal bed methane cbm reservoirs using the recently available sentinel 2 data this study then evaluates the capabilities for mapping the altered minerals and vegetation in the alteration mapping process we separately analyzed the key remote sensing signatures of altered minerals and geobotanical anomalies based on the hydrocarbon micro seepage theory the diagnostic spectral characteristics of irons clays and altered vegetation were concentrated and demonstrated the distribution of hydrocarbon micro seepage in the bare soil region the altered minerals including irons and clays were extracted through band math and principal component analysis pca methods in the vegetation area mapping the diagnostic spectral feature parameters such as the locations and slopes of three feature edges were calculated in addition the mapping accuracy was assessed based on the extraction results of hyperion data through full spectral profile matching method and the x ray diffraction xrd analysis results the results show that 1 compared with band math and pca methods the different extraction methods were suitable for different minerals 2 the extraction results of iron and clay minerals were most accurate 78 33 and 76 67 respectively with xrd analysis 3 the highest rate of change of the feature edge slope was up to 39 with a reference spectrum and 4 the distribution of alteration information was consistent with the hudi coal mining area in jincheng shanxi province the potential geological application of sentinel 2 data was revealed to identify the direction of cbm exploration in a large scale highly efficient convenient and inexpensive way

coalbed gas systems resources and production and a review of contrasting cases from the san juan and powder river basins coalbed gas has been produced commercially from the northern appalachian basin since the 1930s and from the san juan basin since the early 1950s however the magnitude and economic sig nificance of coalbed gas resources were realized only in the 1970s and early 1980s when the u s bureau of mines u s department of energy the gas research institute and oil and gas operators made a concerted effort to demonstrate commercial production of coalbed gas from vertical wells exploration and development ex panded in the late 1980s and early 1990s due partly to an uncon ventional fuels tax credit by 2000 coalbed gas accounted for 8 8 of the reserves 15 7 tcf 0 44 tm3 and 9 2 of the annual pro duction 1 38 tcf 40 gm3 of dry gas in the united states from 1989 through 2000 cumulative united states coalbed gas produc tion was 9 63 tcf 272 gm3 today coalbed gas development has spread to about a dozen basins in the united states and exploration is progressing worldwide coal beds are self sourcing reservoirs that can contain ther mogenic migrated thermogenic biogenic or mixed gas coalbed gas is stored primarily within micropores of the coal matrix in an adsorbed state and secondarily in micropores and fractures as free gas or solution gas in water the key parameters that control gas resources and producibility are thermal maturity maceral compo sition gas content coal thickness fracture density in situ stress permeability burial history and hydrologic setting these param eters vary greatly in the producing fields of the united states and the world in 2000 the san juan basin accounted for more than 80 of the united states coalbed gas production this basin contains a gi ant coalbed gas play the fruitland fairway which has produced more than 7 tcf 0 2 tm3 of gas the fruitland coalbed gas system and its key elements contrast with the fort union coalbed gas play in the powder river basin the fort union coalbed play is one of the fastest developing gas plays in the united states its production escalated from 14 bcf 0 4 gm3 in 1997 to 147 3 bcf 4 1 gm3 in 2000 when it accounted for 10 7 of the united states coalbed gas production by 2001 annual production was 244 7 bcf 6 9 gm3 differences between the fruitland and fort union petroleum systems make them ideal for elucidating the key elements of contrasting coalbed gas petroleum systems

expert system based mineral mapping in northern death valley california nevada using the airborne visible infrared imaging spectrometer aviris abstract integrated analysis of imaging spectrometer data and field spectral measurements were used in conjunction with conventional geologic field mapping to characterize bedrock and surficial geology at the northern end of death valley california and nevada a knowledge based expert system was used to automatically produce image maps showing the principal surface mineralogy from airborne visible infrared imaging spectrometer aviris data linear spectral unmixing of the aviris data allowed further determination of relative mineral abundances and identification of mineral assemblages and mixtures the imaging spectrometer data show the spatial distribution of spectrally distinct minerals occurring both as primary rockforming minerals and as alteration and weathering products field spectral measurements were used to verify the mineral maps and field mapping was used to extend the remote sensing results geographically referenced image maps produced from these data form new base maps from which to develop improved understanding of the prosesses of deposition and erosion affecting the present land surface

reprint of introduction to special issue on geologic remote sensing abstract herein we provide an overview of science and technology involved in remote sensing and outlines some practical constraints in applications to geological problems we further summarize diagnostic spectral features of important geological material that can be detected using satellite and air borne remote sensing finally the papers contained in the special issue are briefly introduced

comparative alteration mineral mapping using visible to shortwave infrared 0 4 2 4 spl mu m hyperion ali and aster imagery advanced land imager ali advanced spaceborne thermal emission and reflection radiometer aster and hyperion imaging spectrometer data covering an area in the central andes between volcan socompa and salar de llullaillaco were used to map hydrothermally altered rocks associated with several young volcanic systems six ali channels in the visible and near infrared wavelength range 0 4 1 0 spl mu m were useful for discriminating between ferric iron alteration minerals based on the spectral shapes of electronic absorption features seen in continuum removed spectra six aster channels in the short wavelength infrared 1 0 2 5 spl mu m enabled distinctions between clay and sulfate mineral types based on the positions of band minima related to al oh vibrational absorption features hyperion imagery embedded in the broader image coverage of ali and aster provided essential leverage for calibrating and improving the mapping accuracy of the multispectral data this capability is especially valuable in remote areas of the earth where available geologic and other ground truth information is limited

pyroxene spectroscopy revisited spectral compositional correlations and relationship to geothermometry the authors wish to thank the various agencies which have provided the necessary support for this project including grants in aid of research from sigma xi the scientific research society to e a c the geological society of america grant 3741 87 to e a c and nasa planetary geology and geophysics grant nagw 642 to m j g

comparison of airborne hyperspectral data and eo 1 hyperion for mineral mapping airborne hyperspectral data have been available to researchers since the early 1980s and their use for geologic applications is well documented the launch of the national aeronautics and space administration earth observing 1 hyperion sensor in november 2000 marked the establishment of a test bed for spaceborne hyperspectral capabilities hyperion covers the 0 4 2 5 spl mu m range with 242 spectral bands at approximately 10 nm spectral resolution and 30 m spatial resolution analytical imaging and geophysics llc and the commonwealth scientific and industrial research organisation have been involved in efforts to evaluate validate and demonstrate hyperions s utility for geologic mapping in a variety of sites in the united states and around the world initial results over several sites with established ground truth and years of airborne hyperspectral data show that hyperion data from the shortwave infrared spectrometer can be used to produce useful geologic mineralogic information minerals mapped include carbonates chlorite epidote kaolinite alunite buddingtonite muscovite hydrothermal silica and zeolite hyperion data collected under optimum conditions summer season bright targets well exposed geology indicate that hyperion data meet prelaunch specifications and allow subtle distinctions such as determining the difference between calcite and dolomite and mapping solid solution differences in micas caused by substitution in octahedral molecular sites comparison of airborne hyperspectral data from the airborne visible infrared imaging spectrometer aviris to the hyperion data establishes that hyperion provides similar basic mineralogic information with the principal limitation being limited mapping of fine spectral detail under less than optimum acquisition conditions winter season dark targets based on lower signal to noise ratios case histories demonstrate the analysis methodologies and level of information available from the hyperion data they also show the viability of hyperion as a means of extending hyperspectral mineral mapping to areas not accessible to aircraft sensors the analysis results demonstrate that spaceborne hyperspectral sensors can produce useful mineralogic information but also indicate that snr improvements are required for future spaceborne sensors to allow the same level of mapping that is currently possible from airborne sensors such as aviris

lithologic mapping in the mountain pass california area using advanced spaceborne thermal emission and reflection radiometer aster data abstract evaluation of an advanced spaceborne thermal emission and reflection radiometer aster image of the mountain pass california area indicates that several important lithologic groups can be mapped in areas with good exposure by using spectral matching techniques the three visible and six near infrared bands which have 15 m and 30 m resolution respectively were calibrated by using in situ measurements of spectral reflectance calcitic rocks were distinguished from dolomitic rocks by using matched filter processing in which image spectra were used as references for selected spectral categories skarn deposits and associated bright coarse marble were mapped in contact metamorphic zones related to intrusion of mesozoic and tertiary granodioritic rocks fe muscovite which is common in these intrusive rocks was distinguished from al muscovite present in granitic gneisses and mesozoic granite quartzose rocks were readily discriminated and carbonate rocks were mapped as a single broad unit through analysis of the 90 m resolution five band surface emissivity data which is produced as a standard product at the eros data center three additional classes resulting from spectral angle mapper processing ranged from 1 a broad granitic rock class 2 to predominately granodioritic rocks and 3 a more mafic class consisting mainly of mafic gneiss amphibolite and variable mixtures of carbonate rocks and silicate rocks

cumulatic diorites related to post collisional brasiliano pan african mafic magmatism in the vila nova belt southern brazil abstract the capivaras diorite in the vila nova region nw of the sul rio grandense shield is composed of six ne to nne oriented rock bodies of late tectonic emplacement relative to the d3 deformation phase which forms subvertical high strain zones in basement gneiss sequences within these intrusive bodies a shape foliation is present generally parallel to contacts and displaying a local solid state deformational component the internal structure of the capivaras diorite main intrusion is marked by a zone of intense flow and mingling characterized by strong shape foliation and layers of variable texture and composition which result from cumulative processes heterogeneous flow and interaction of coeval compositionally contrasting magmas the central part of this intrusion is texturally homogeneous and slightly foliated even though cumulative processes have remained important during its formation along the contact with basement gneisses fine grained diorites are found which are considered to be compositionally close to the parental magma of the capivaras diorite this magma has a mildly alkaline affinity and shows moderate to high contents of zr ti and p highly fractionated ree patterns low nb contents as well as high contents of k sr ba and rb are suggestive of its provenance from mantle sources which have been previously affected by subduction processes such as those of mature magmatic arcs or post collisional settings magmatic evolution was controlled by cumulative processes and gave origin to pyroxene orthocumulates plagioclase pyroxene orthocumulates pyroxene adcumulates and more rarely plagioclase adcumulates the cumulative origin of these rocks is indicated by field textural and geochemical features which are distinct from those of crystallized liquids the compositional diversity of cumulates has led to the generation of compositionally different melts the early formed pyroxene cumulates have caused ca al na ba and sr enrichment in the magmatic liquid leading to plagioclase crystallization and accumulation coarse grained mafelsic cumulates were formed during the late stages of magmatic crystallization due to volatile enrichment of the intercumulus liquid considering geological relations as well as tectonic and compositional features of the capivaras diorite it is interpreted as part of neoproterozoic magmatism related to the post collisional stage of brasiliano pan african orogenic cycle in southern brazil

the application of aster remote sensing data to porphyry copper and epithermal gold deposits abstract this paper reviews the performance characteristics of the advanced spaceborne thermal emission and reflection radiometer aster remote sensor the standard data products and applications of the most recently developed image processing methods applied to aster data as a tool for mapping hydrothermal alteration mineral zones associated with porphyry copper and epithermal gold mineralization and related host rock lithology hydrothermal alteration zones associated with porphyry copper deposit such as phyllic argillic and propylitic mineral assemblages can be discriminated from one another by virtue of their spectral absorption features which are detectable by aster swir spectral bands the identification of the phyllic zone is important in the initial stages of porphyry copper exploration as an indicator of high economic potential for copper mineralization two new crosstalk corrected aster swir reflectance products including ast 07xt and refl1b are more reliable than previous aster data products for regional mineral mapping without use of additional spectral data from the site for calibration four types of algorithms were used to extract spectral information of aster data 1 band ratio indices and logical operator based methods 2 principal components and enhancement based methods such as principal component analysis pca and minimum noise fraction mnf 3 shape fitting based algorithms such as spectral angle mapper sam matched filtering mf and mixture tuned matched filtering mtmf and 4 partial unmixing methods such as linear spectral unmixing lsu and constrained energy minimization cem this review emphasizes that the logical operator algorithms can be best suited for hydrothermal alteration mineral mapping including phyllic and argillic zones associated with porphyry copper mineralization in a regional scale shape fitting based and partial unmixing algorithms are robust and reliable for detecting particular mineral and mineral assemblages in hydrothermal alteration zones in a district scale consequently the integration of the results derived from the logical operator shape fitting based and partial unmixing algorithms can produce comprehensive and accurate information for the reconnaissance stages of copper and gold exploration at both regional and district scales all of the methods and applications reviewed in this paper demonstrate the utility of aster data for exploration of the porphyry copper and epithermal gold deposits around the world

dynamic monitoring of coalbed methane reservoirs using super low frequency electromagnetic prospecting abstract dynamic monitoring of coalbed methane cbm reservoirs plays an important role in reservoir evaluation production estimation exploitation and development planning in order to efficiently operate producing wells this paper proposes a passive super low frequency slf electromagnetic prospecting and monitoring method which helps us derive electromagnetic radiation emr anomalies from reservoirs to directly identify and dynamically analyze cbm reservoirs the modeling study shows that the slf magnetic responses are sensitive to high resistivity layers these responses turn out to be approximately stationary and can be seen as simply a component of the background field this stationary background field can be clearly distinguished and then dynamic anomaly extraction would be completed in order to suppress cultural noise and high frequency hf random noise the methods of empirical mode decomposition emd and wavelet transform are used in data processing the reconstructed curves are employed to identify emr anomalies at corresponding depths of reservoirs and subsequently help directly interpret and dynamically monitor reservoirs the slf prospecting method is validated using the field data observed from cbm wells in the years from 2007 to 2013 in qinshui basin china the results present that the high emr wave packets contribute conceivably to the cbm reservoir identification compared with audio magnetotelluric amt inversion results the slf identification resolution is greatly improved the dynamic characteristics of producing reservoirs are revealed using emr anomalies and agree with production histories and other surveys

mapping and characterization of the api gravity of offshore hydrocarbon seepages using multispectral aster data abstract the objective of this work is the qualitative remote characterization api gravity degree of oil seepages on the ocean surface in order to achieve this goal multispectral data acquired by the advanced spaceborne thermal emission and reflection aster sensor are employed aster registered tracts of oil along oceanic sectors of the campos basin brazil and the bay of campeche gulf of mexico in several occasions numerous evidences indicate that these oil patches bear a straight link to oceanic seepages the delimitation and segmentation of these seepages in the aster imagery are accomplished making use of an unsupervised neural network fuzzy clustering algorithm spectra representative of the seepages are extracted from atmospherically corrected aster data pixels 9 bands spanning from visible to shortwave infrared wavelengths contained in the classified segments the aster spectra are checked against a predictive api partial least square regression model this model is established on the basis of oil spectra of known oapi varying from 13 to 47 yielded by laboratory measurements considering this model api gravity degrees of 19 6 1 37 and 15 9 2 9 are remotely estimated for the seepage in the campos basin and the bay of campeche respectively oils produced from campos and campeche fields typically show api varying from 17 24 and 12 16 5 correspondingly these results indicate the potential of the methodology proposed and of aster data and alike to remotely infer physical chemical properties of hydrocarbons since a close match was verified between predicted and true api gravity degrees for both study areas the data methods and experience gained in this research can be operationally tested in offshore oil exploration and likewise be adapted to environmental monitoring of oil spills in coastal regions

rapid determination of coalbed methane exploration target region utilizing hyperspectral remote sensing abstract this study reveals the common surface mineral characteristics over coalbed methane cbm enrichment regions from spaceborne hyperion images and the possibility of hyperspectral remote sensing for prospecting coalbed methane exploration target region with an inexpensive large scale rapid and convenient way for this study a typical scheme including bands removal atmospheric correction snr estimation minimum noise fraction mnf pixel purity index ppi and n dimensional visualization was applied on hyperion image in qinshui basin china to accurately extract mineral endmembers the endmember spectra of carbonate and clay mineral were identified based on the diagnostic absorption feature while no endmember of ferrous iron mineral was found the absorption feature parameters of carbonate absorption position and especially asymmetric factor and clay mineral absorption position left and right shoulder positions were quantitatively estimated which showed the endmember spectra of carbonate and clay mineral from hyperspectral images in this paper were correct in addition this study proposed an interesting research direction measuring the asymmetric absorption factor to facilitate the identification of carbonates furthermore spectral angle mapper sam and spectral feature fitting sff were used to map carbonates and clay minerals two assessment methods visual interpretation based on field spectra and x ray diffraction xrd analysis were utilized to evaluate the mapping accuracy which showed total agreements of 84 03 and 72 58 respectively the results in this paper suggested that both carbonates and clay minerals were rich while there was hardly any ferrous iron mineral on the surface of cbm enrichment regions in addition another similar experiment was carried out in ordos basin and also showed similar surface mineral characteristics on cbm enrichment region

integrating visible near infrared and short wave infrared hyperspectral and multispectral thermal imagery for geological mapping at cuprite nevada this study investigated the potential value of integrating hyperspectral visible near infrared and short wave infrared imagery with multispectral thermal data for geological mapping two coregistered aerial data sets of cuprite nevada were used airborne visible infrared imaging spectrometer aviris hyperspectral data and modis aster airborne simulator master multispectral thermal data four classification methods were each applied to aviris master and a combined set confusion matrices were used to assess the classification accuracy the assessment showed in terms of kappa coefficient that most classification methods applied to the combined data achieved a marked improvement compared to the results using either aviris or master thermal infrared tir data alone spectral angle mapper sam showed the best overall classification performance minimum distance classification had the second best accuracy followed by spectral feature fitting sff and maximum likelihood classification the results of the study showed that sff applied to the combination of aviris with master tir data are especially valuable for identification of silicified alteration and quartzite both of which exhibit distinctive features in the tir region sam showed some advantages over sff in dealing with multispectral tir data obtaining higher accuracy in discriminating low albedo volcanic rocks and limestone which do not have unique distinguishing features in the tir region

alteration mineralogy at the cerro la mina epithermal prospect patagonia argentina field mapping short wave infrared spectroscopy and aster images the cerro la mina prospect located in the los menucos area argentina is currently being explored for epithermal gold mineralization triassic jurassic hydrothermal activity produced intense alteration of rhyolites andesites ignimbrites and tuffs of the late triassic los menucos group in the somun cura massif a detailed surface map of the principal alteration assemblages at cerro la mina was produced employing field mapping supported by short wave infrared swir field spectroscopy petrography x ray diffraction xrd and scanning electron microscopy sem advanced argillic argillic and silicic alteration zones and their internal mineral assemblage variations were recognized at cerro la mina the silicification consists of massive bodies of fine grained quartz and minor vuggy quartz locally containing disseminated aggregates of pyrite and rutile advanced argillic alteration of magmatic hydrothermal origin occurs adjacent to the silicic alteration zones and can be subdivided into three mineral assemblages 1 stage 1 alunite quartz dickite kaolinite pyrophyllite diaspore rutile pyrite barite 2 dickite kaolinite pyrophyllite diaspore pyrite barite and 3 dickite quartz diaspore the advanced argillic and silicic alteration grades to argillic alteration comprising three mineral assemblages 1 kaolinite dickite quartz illite smectite 2 kaolinite illite smectite ferroan clinochlore and 3 illite quartz muscovite kaolinite supergene alteration which locally overprints the prior alteration zones consists of jarosite hematite goethite stage 2 alunite aluminum phosphate sulfate aps poorly crystalline kaolinite consistent discrimination of the main alteration minerals of this prospect was also achieved by means of satellite multispectral remote sensing the application of image processing techniques specifically designed for mineral mapping to selected spectral bands of the terra aster multispectral sensor resulted in a detailed alteration map for the entire prospect comparison between the results achieved through remote sensing with field data on the cerro la mina confirmed the accuracy of the former the silicification and minor vuggy quartz the abundant dickite and the coarse grained hypogene alunite among other advanced argillic alteration assemblages suggest that cerro la mina corresponds to a volcanic hydrothermal leached environment possibly controlled by permeable lithological units these characteristics led us to interpret this prospect as a possible lithocap similar to those that typically host subsequent high sulfidation mineralization

production waters associated with the ferron coalbed methane fields central utah chemical and isotopic composition and volumes this study investigated the composition of water co produced with coalbed methane cbm from the upper cretaceous ferron sandstone member of the mancos shale in east central utah to better understand coalbed methane reservoirs the ferron coalbed methane play currently has more than 600 wells producing an average of 240 bbl day well water water samples collected from 28 wellheads in three fields buzzards bench drunkards wash and helper state of the northeast southwest trending play were analyzed for chemical and stable isotopic composition water produced from coalbed methane wells is a na cl hco3 type water from the drunkards wash field has the lowest total dissolved solids tds 6300 mg l increasing in value to the southeast and northeast in the helper state field about 6 miles northeast water has the highest total dissolved solids 43 000 mg l and major ion abundance indicates the possible influence of evaporite dissolution or mixing with a saline brine in the southern buzzards bench field water has variable total dissolved solids that are not correlated with depth or spatial distance significant differences in the relative compositions are present between the three fields implying varying origins of solutes and or different water rock interactions along multiple flow paths stable isotopic values of water from the ferron range from 0 9 to 11 4 18o and 32 to 90 2h and plot below the global meteoric water line gmwl on a line near but above values of present day meteoric water isotopic values of ferron water are consistent with modification of meteoric water along a flow path by mixing with an evolved seawater brine and or interaction with carbonate minerals analysis of isotopic values versus chloride conservative element and total dissolved solids concentrations indicates that recharge water in the buzzards bench area is distinct from recharge water in drunkards wash and is about 3 c warmer these variations in isotopes along with compositional variations imply that the ferron reservoir is heterogeneous and compartmentalized and that multiple flow paths may exist

west gondwana amalgamation based on detrital zircon ages from neoproterozoic ribeira and dom feliciano belts of south america and comparison with coeval sequences from sw africa

time constraints on magmatism along the major gercino shear zone southern brazil implications for west gondwana reconstruction the dom feliciano belt situated in southernmost brazil and uruguay contains a large mass of granite gneissic rocks also known as florianopolis pelotas batholith formed during the pre syn and post orogenic phases of the brasiliano pan african cycle in the ne extreme of this granitic mass pre syn and post tectonic granites associated with the major gercino shear zone mgsz are exposed the granitic manifestation along the mgsz can be divided into pre kinematic tonalitic gneisses peraluminous high k calc alkaline early kinematic shoshonitic and metaluminous post kinematic granites u pb zircon data suggest an age of 649 10 ma for the pre tectonic gneisses and a time span from 623 6 ma to 588 3 ma for the early to post tectonic magmatism negative ehf t values ranging from 4 6 to 14 6 and hf model ages ranging from 1 64 to 2 39 ga for magmatic zircons coupled with whole rock nd model ages ranging from 1 24 to 2 05 ga and end t values ranging from 3 84 to 7 50 point to a crustal derivation for the granitic magmatism the geochemical and isotope data support a continental magmatic arc generated from melting of dominant paleoproterozoic crust and a similar evolution for the granitic batholiths of the eastern dom feliciano belt and western kaoko belt

relationships between water and gas chemistry in mature coalbed methane reservoirs of the black warrior basin water and gas chemistry in coalbed methane reservoirs of the black warrior basin reflects a complex interplay among burial processes basin hydrodynamics thermogenesis and late stage microbial methanogenesis these factors are all important considerations for developing production and water management strategies produced water ranges from nearly potable sodium bicarbonate water to hypersaline sodium chloride brine the hydrodynamic framework of the basin is dominated by structurally controlled fresh water plumes that formed by meteoric recharge along the southeastern margin of the basin the produced water contains significant quantities of hydrocarbons and nitrogen compounds and the produced gas appears to be of mixed thermogenic biogenic origin late stage microbial methanogenesis began following unroofing of the basin and stable isotopes in the produced gas and in mineral cements indicate that late stage methanogenesis occurred along a co2 reduction metabolic pathway hydrocarbons as well as small amounts of nitrate in the formation water probably helped nourish the microbial consortia which were apparently active in fresh to hypersaline water the produced water contains nh4 and nh3 which correlate strongly with brine concentration and are interpreted to be derived from silicate minerals denitrification reactions may have generated some n2 which is the only major impurity in the coalbed gas carbon dioxide is a minor component of the produced gas but significant quantities are dissolved in the formation water degradation of organic compounds augmented by deionization of nh4 may have been the principal sources of hydrogen facilitating late stage co2 reduction

an integrated approach to the late stages of neoproterozoic post collisional magmatism from southern brazil structural geology geochemistry and geochronology of the corre mar granite abstract the neoproterozoic post collisional stage in south brazil is marked by intense granitic magmatism controlled by transcurrent shear zones related to the southern brazilian shear belt sbsb the sbsb has controlled the ascent and emplacement of magmas from crust and mantle in such scenario the corre mar granite cmg represents a small intrusion emplaced in a low strain zone located between two important segments of the sbsb the major gercino and itajai perimbo shear zones the cmg has a diagnostic subvertical s c foliation pair present in all intrusions regardless of their size it was emplaced within a conjugate system where sinistral nne shearing and nw se extension were both active generating space along the ne direction solid state deformation associated to the nne shearing is attested to by microstructures as feldspar recrystallization and asymmetric recrystallization tails the opening is attributed to the regional dextral transcurrent dynamics of the major gercino and itajai perimbo shear zones and magma emplacement was essentially conditioned by the nw extension component zircon u pb la mc icp ms crystallization age of cmg at 615 4 ma very close to other regional granites as the 611 ma serra dos macacos smg and 620 ma rio pequeno granite rpg points these three granitic bodies as synchronous the strong deformation features present in the cmg as opposed to the other neoproterozoic granites demonstrate that space rather than time must be called upon to explain the difference in structural patterns identified in the cmg geochemical and sr nd isotopic signatures as the slightly peraluminous character high k contents high lree hree ratios moderate rb nb zr and ree contents to regular sio 2 together with low 87 sr 86 sr i and the strongly negative nd t values indicate that the cmg is derived from old crustal sources possibly related to the paleoproterozoic camboriu complex quartz feldspathic orthogneisses the coincidence of cmg archean to paleoproterozoic inheritance ages with the age of a migmatization event identified in the camboriu complex and moreover the coincidence of the crystallization age intervals of the granites 615 611 ma with the last migmatization event at 640 610 ma reinforces the genetic link between them the paleoproterozoic tdm ages the geochemical and isotopic signatures the zircon u pb crystallization and inheritance age and the resemblance of the cmg and the smg suggest that they represent comagmatic and contemporaneous granitic pulses with a possible genetic link with the neoproterozoic migmatization event in the camboriu complex

remote sensing and geochemistry for detecting hydrocarbon microseepages this work tests the hypothesis that chemical and mineralogical alterations in rocks and soils are related to hydrocarbon microseepages above some of the major oil fields in this study we used hyperion hyperspectral imaging sensors to map alterations that appear to be associated with hydrocarbon microseepages in the patrick draw area of wyoming our mineralogical geochemical and carbon isotope data support the presence of hydrocarbon microseepages satellite imagery training classifications defined by areas of hydrocarbon microseepage have resulted in the successful identification of the areal extent of an anomalous area geochemical characteristics of samples that define this anomalous area were then compared to the remaining non anomalous samples using x ray diffraction xrd reflectance spectroscopy and carbon isotope techniques xrd analyses demonstrated the increased presence of feldspars in non anomalous samples compared to anomalous samples spectroscopy results demonstrated higher proportions of clays within the anomalous samples compared to non anomalous samples the 13 c values range from 2 88 to as low as 45 32 indicating hydrocarbon sources these methods may provide a foundation upon which further hydrocarbon exploration techniques can develop

mapping hydrocarbon induced mineralogical alteration in the northern tian shan using aster multispectral data seepage from hydrocarbon reservoirs can cause a number of chemical and or mineralogical changes in overlying rocks and soils these surface changes can be detected by remote sensing imaging systems the advanced spaceborne thermal emission and reflection radiometer aster is an advanced multispectral imaging system in the visible and near infrared vnir to shortwave infrared swir region band ratios of aster vnir and swir data to detect red bed bleaching and secondary carbonate formation induced by hydrocarbon seepage are proposed through analysis of the spectral properties of rock samples results show that aster band ratios of 2 1 and 4 8 can discriminate bleached red beds and secondary carbonate minerals due to hydrocarbon seepage in the northern tian shan they are in good agreement with mineral identification using x ray diffraction the ratio technique derived from aster data may provide a potential approach for hydrocarbon exploration in areas with sparse vegetation cover

preliminary evaluation of the coalbed methane production potential and its geological controls in the weibei coalfield southeastern ordos basin china article i nfo the coalbed methane cbm geology resource and production potential in the weibei coalfield southeastern ordos basin are studied based on geological surveys and laboratory measurements the results showed that coal rank varies both laterally and vertically and changes from volatile bituminous coals in the margin to anthracites towards the basin 1 6 2 5 ro coals are composed of 60 85 vitrinite 15 40 inertinite and a trace amount of minerals methane isothermal adsorption measurements of 20 coal samples revealed that the maximum adsorption capacity on a dry and ash free basis of coals which are affected by coal rank coal maceral coal lithotype and especially to the moisture content varies from 13 91 to 29 54 m 3 t estimated gas contents range from 0 to 15 m

prism and basal plane parallel subgrain boundaries in quartz a microstructural geothermobarometer empirical data on quartz subgrain patterns from various metamorphic rocks show that at least up to 10 kbar in the stability field of low quartz prismatic subgrain boundaries are dominant whereas basal subgrain boundaries are not developed in the high quartz stability field both prismatic and basal subgrain boundaries occur and form typical rectangular chessboard patterns the likely reason behind the different occurrence of these subgrain patterns is that in high quartz prismatic glide becomes as easy as or probably even easier than basal glide the two types of subgrain patterns can be clearly distinguished by optical microscopy consequently the occurrence of chessboard subgrain patterns in quartz represents a practicable geothermobarometer the possibilities of its application are far reaching and include the specification of deformation conditions at high grade metamorphism the recognition of syntectonic intrusions and the distinction between pluton emplacement at lower and at higher crustal levels

dynamic recrystallization in deformed plagioclase during progressive shear deformation grain size reduction of plagioclase accompanied with progressive ductile deformation was investigated in a centimeter scale small shear zone collected from the hatagawa shear zone northeast japan the angle between the foliation and the shear zone boundary decreases from the margin to the center of the shear zone indicating an increase of shear strain toward the center the volume fraction of fine plagioclase grains xpl diameter 15 m increases with progressive shear strain the value of xpl increases steeply from 30 to 60 between the angles 23 and 20 and then it gradually increases from 60 to 90 toward 0 the fine plagioclase grains have a variable dislocation density and a crystallographic preferred orientation suggesting that recrystallization accommodated dislocation creep transmission electron microscopy tem observations revealed that strain induced grain boundary bulging occurred along the grain boundaries of plagioclase porphyroclasts thus the grain size of plagioclase was reduced by strain induced grain boundary bulging the kinetic theory of dynamic recrystallization approximately predicts the formation of the above mentioned xpl curve and suggests that the inflection point of xpl at 23 20 is probably due to site saturation in which all of the original grain boundaries are covered by the recrystallized grains the kinetic theory of dynamic recrystallization also gives a physical basis for the classification of mylonite on the basis of the volume fraction of fine grains

compositional changes of minerals associated with dynamic recrystallizatin the rate of compositional and isotopic exchange between minerals may be enhanced significantly if the rock is deformed simultaneously the enhanced exchange rate may result from a reduction in grain size shorter distance for volume diffusion dissolution and growth of grains by diffusion creep pressure solution or the movement of high angle grain boundaries through strained grains during recrystallization in the dislocation creep regime the migration of high angle grain boundaries provides high diffusivity paths for the rapid exchange of components during recrystallization the operation of the latter process has been demonstrated by deforming aggregates consisting of two plagioclases an1 and an79 at 900 c 1 gpa confining pressure and a strain rate of 2x10 6s 1 the polygonal recrystallized grains were analyzed using an analytical transmission electron microscope and have a variable but often intermediate composition at the conditions of these experiments the volume interdiffusion rate of nasi caal is too slow to produce any observable chemical change and microstructural chemical relations indicate that the contribution from diffusion creep was insignificant except for initially fine grained 2 10 m aggregates these results indicate that strain induced recrystallization can be an effective mechanism for enhancing the kinetics of metamorphic reactions and for resetting the isotope systematics of minerals such as feldspars pyroxenes and amphiboles

potential of esa s sentinel 2 for geological applications abstract sentinel 2 is esa s medium spatial resolution 10 60 m super spectral instrument aimed at ensuring data continuity for global land surface monitoring of landsat and spot several simulation studies have been conducted that show the potential of sentinel 2 for estimating biophysical and biochemical parameters such as leaf area index chlorophyll and nitrogen and spectral products such as the red edge position and ndvi time series providing data continuity for a number of other operational sensors this paper aims at simulating sentinel 2 products that are relevant to the geology and soil science community and we compare these to well established band ratio products from aster as the basis for the simulation we use airborne hyperspectral imagery from the hymap sensor which were spectrally and spatially resampled to the resolutions of aster and sentinel 2 using actual spectral response functions and pixel aggregate respectively the simulated image products demonstrate a good correspondence between aster and sentinel 2 vnir and swir bands a number of band ratios are proposed for sentinel 2 to derive the following products ferric iron ferrous iron laterite gossan ferrous silicate and ferric oxides these are compared to established band ratios of real aster data as well as simulated from hymap aster data and they correlate favourably investigating the spatial patterns reveals that there is a good match between the proposed sentinel 2 band ratio products and those of aster the resulting band ratio products are compared to the local geologic map of the imaged hydrothermal area the rodalquilar mining area cabo de gata volcanic field se spain it is shown that they support the existing conceptual geologic model of the epithermal deposit

geochemistry and field spectrometry for detecting hydrocarbon microseepage remote sensing detection of hydrocarbon reserves would be a valuable addition to conventional methods used currently tests were made in a drilled proven hydrocarbon area predominantly covered by wheat field spectroradiometers measured spectral characteristics of wheat and soil associated with hydrocarbon microseepage soil gas and secondary carbonate produced only by hydrocarbon microseepage were at anomalously high levels at the oil water or gas water boundaries kaolinite and illite in the soil have higher percentages above petroleum reservoirs the inflection point positions of spectra on oil field wheat were shifted 7 nm to longer wavelengths than off field wheat samples and can be positively correlated with the delta carbonate and soil gas the absorption of soil spectra at 2 346 mm is at least 0 2 higher over oil fields than off fields this research proves that remote sensing can be used in an monocultural agricultural area to detect hydrocarbon microseepage

characterization of aster spectral bands for mapping of alteration zones of volcanogenic massive sulphide deposits abstract in this study the oxidized and hydrothermally altered zones including propylitic argillic and phyllic zones associated with volcanogenic massive sulphide deposits in the sohar shinas region of the sultanate of oman are studied based on absorption characters of spectral bands of advanced spaceborne thermal emission and reflection radiometer aster in this work we have used selected imaging processing methods including decorrelation stretching band ratios linear spectral unmixing lsu and mixture tuned matched filtering mtmf as well as petrological and geochemical characteristics of the alteration zones to map and understand the distribution of these alteration zones results indicate that 1 the decorrelation of aster spectral bands 3 6 and 8 discriminate extrusive basalts and the host lithology of altered zones 2 the application of aster band ratios 5 3 1 2 oxidized zone 4 6 5 argillic zone and 5 7 6 phyllic zone delineate alteration zones spatially associated with mineralized zones 3 the utilization of aster indices for oh bearing altered minerals e g kaolin and alunite indices confirmed the presence of alteration minerals in the mineralized zone 4 alteration end members derived using the spectral angle mapper sam method in combination with linear spectral unmixing lsu can be used to map the distribution of the weathering and alteration zones 5 short wavelength infrared swir measurements on field samples were used to confirm spectral measurements from aster data and 6 microscopic study and xrd analysis of field samples confirmed the presence of hematite and goethite in the oxidized zone chlorite epidote and calcite in the propylitic zone kaolin and chlorite in the argillic zone sericite and illite in the phyllic zone the major minerals responsible to absorptions of aster bands 3 8 5 and 6 respectively this study demonstrated the sensor capability of aster and the potential use of the image processing methods and documented the spectral absorptions values of the altered minerals and the field and mineralogical characters of alteration zones of the volcanogenic massive sulphide deposits to map similar deposits elsewhere

structure and evolution of north choctaw ridge field alabama a salt related footwall uplift along the peripheral fault system gulf coast basin abstract north choctaw ridge ncr field is in a structural trap that produces from the jurassic smackover formation in the gilbertown graben system near the updip limit of the louann salt the field is in a footwall uplift below the southernmost of the three faults that form the northern boundary of the graben system the top seal is anhydrite in the overlying buckner member of the haynesville formation and the boundary fault provides a lateral seal the geometry and evolution of the structure has been determined from a three dimensional interpretation of the graben system and from a balanced and sequentially restorable cross section the cross section is both area and length balanced with a lower detachment in the louann salt significant structural growth began in early cretaceous time when three major south dipping down to the gulf faults formed creating an imbricate system of half grabens the melvin fault system regional subsidence in the hangingwall of the melvin fault system indicates contemporaneous salt deflation with the ncr field subsiding the least the north dipping boundary fault of the gilbertown graben system east gilbertown fault developed in the late cretaceous late cretaceous and tertiary extension produced a full graben between the east gilbertown and melvin c faults

post collisional transition from calc alkaline to alkaline magmatism during transcurrent deformation in the southernmost dom feliciano belt braziliano pan african uruguay abstract in the southernmost dom feliciano belt of uruguay highly fractionated calc alkaline granites mildly alkaline granites shoshonitic volcanics and peralkaline intrusions and volcanics are spatially and temporal associated with the evolution of shear zones four representative magmatic unites of this diverse association were petrographic and geochemically investigated the solis de mataojo complex a medium to high k2o calc alkaline granite with signature typical of mature continental arcs and post collisional settings the maldonado granite highly fractionated calc alkaline to alkaline with characteristics that are transitional between both types of series the pan de azucar pluton with characteristics typical of post collisional alkaline granites and the las flores shoshonitic basalts geochemistry and geotectonic setting point out that slab breakoff was most likely the mechanism associated with the generation of high k calc alkaline magmas solis de mataojo and maldonado shortly after collision extension associated to the formation of molassic basins and emplacement of dolerites and basalt flows with shoshonitic affinity las flores 15and finally a shift to magmas with alkaline signatures pan de azucar simultaneous with a second transpressional phase were probably linked with lithospheric thinning through delamination this evolution took place between 615 and 575 ma according to available data contrary to previous proposals which considered this magmatism to represent the root of a continental magmatic arc a post collisional environment transitional from orogenic to anorogenic during transcurrent deformation is proposed

geochronological constraints on the evolution of the southern dom feliciano belt uruguay abstract new u pb sensitive high resolution ion microprobe k ar and ar ar data from the southernmost dom feliciano belt allow the identification of four major events orthogneisses from the punta del este terrane indicate a magmatic episode at c 770 ma and high grade metamorphism at 641 17 ma granitoid emplacement at 627 23 ma was roughly coeval with peak metamorphism volcaniclastic rocks of the las ventanas formation dated at 573 11 ma can be correlated with the peripheral foreland basin 571 8 ma transpression and coeval high k calc alkaline magmatism is recorded in the maldonado granite dated at 564 7 ma the following events are postulated 1 magmatism at 850 750 ma related to rifting 2 metamorphism and granite emplacement at 650 600 ma 3 molasse sequences and foreland basins at c 573 ma 4 late magmatism at 580 560 ma associated with transpression the data indicate that 1 the punta del este terrane could be a portion of the coastal terrane of the kaoko belt 2 granitoid emplacement at 650 600 ma in the punta del este and nico perez terranes favours westward subduction and 3 widespread post collisional synkinematic magmatism occurred in the dom feliciano and kaoko belts between 580 and 550 ma supplementary material analytical methods and data are available at http www geolsoc org uk sup18369