authigenic uranium relationship to oxygen penetration depth and organic carbon rain we have measured u in benthic incubation chambers sediment pore waters and in sediments along the california continental margin sedimentary u uptake rates based on a combination of sediment pore water profiles and benthic incubation chambers generally agree with those predicted from sediment accumulation rate data this agreement supports the view that most of the continental margin sedimentary u is delivered by diffusion across the seawater sediment boundary the average rate of authigenic u accumulation for all the sites examined here is 0 2 nmol cm 2 y 1 which is consistent with published global estimates of sedimentary u uptake in addition the accumulation rate of u in sediments exhibits a nonlinear relationship with the oxygen penetration depth and a linear relationship with the organic carbon rain rate these relationships highlight the potential utility for the u accumulation rate as a proxy for these processes

early triassic seawater sulfate drawdown abstract the marine sulfur cycle is intimately linked to global carbon fluxes atmospheric composition and climate yet relatively little is known about how it responded to the end permian biocrisis the largest mass extinction of the phanerozoic here we analyze carbonate associated sulfate cas from three permo triassic sections in south china in order to document the behavior of the c s cycle and its relationship to marine environmental changes during the mass extinction and its aftermath we find that 34 s cas varied from 9 to 44 at rates up to 100 myr 1 during the griesbachian smithian substages of the early triassic we model the marine sulfur cycle to demonstrate that such rapid variation required drawdown of seawater sulfate concentrations to 4 mm and a reduction in its residence time to 200 kyr this shorter residence time resulted in positive covariation with 13 c carb due to strong coupling of the organic carbon and pyrite burial fluxes carbon and sulfur isotopic shifts were associated with contemporaneous changes in climate marine productivity and microbial sulfate reduction rates with negative shifts in 13 c carb and 34 s cas linked to warming decreased productivity and reduced sulfate reduction sustained cooling during the spathian re invigorated oceanic overturning circulation reduced marine anoxia and limited pyrite burial as seawater sulfate built to higher concentrations during the spathian the coupling of the marine c and s cycles came to an end and a general amelioration of marine environmental conditions set the stage for a recovery of invertebrate faunas variation in seawater sulfate during the early triassic was probably controlled by climate change possibly linked to major eruptive phases of the siberian traps

hyperspectral analysis of the ultramafic complex and adjacent lithologies at mordor nt australia abstract the mordor complex consists of a series of potassic ultramafic rocks which were intruded into proterozoic felsic gneisses and amphibolite and are overlain by quartzite and unconsolidated deposits in situ and laboratory 0 4 to 2 5 m reflectance spectra show al oh absorption features caused by absorption in muscovite kaolinite and illite smectite in syenite granitic gneiss quartzite and unconsolidated sedimentary deposits and fe mg oh features due to phlogopite biotite epidote and hornblende in the mafic and ultramafic rocks ferrous iron absorption positioned near 1 05 m is most intense in peridotite reflectance spectra ferric iron absorption is intense in most of the felsic lithologies hymap data were recorded in 126 narrow bands from 0 43 to 2 5 m along a 7 km wide swath with approximately 6 m spatial resolution correction of the data to spectral reflectance was accomplished by reference to in situ measurements of an extensive alluvial plain spectral classes for matched filter processing were selected by using the pixel purity index procedure and analysis of in situ and laboratory spectra considering the spatial distribution of the resulting 14 classes some classes were combined which produced eight classes characterized by al oh absorption features and three fe mg oh absorption feature classes comparison of the distribution of these 11 spectral classes to a generalized lithologic map of the study area shows that the spectral distinction among the eight al oh classes is related to variations in primary lithology weathering products and vegetation density quartzite is represented in three classes syenite corresponds to a single scattered class quartz muscovite biotite schist defines a single very coherent class and unconsolidated sediments are portrayed in four classes the three mafic ultramafic classes are distinguished on the basis of generally intense fe mg oh and ferrous iron absorption features a single class represents the main mordor ultramafic mass epidote bearing rocks define another class which corresponds to biotite gneiss and in the southern part of the area to fracture zones the third class which exhibits al oh as well as fe mg oh features represents hornblende gneiss and other mafic gneisses these results indicate the importance of analyzing the vnir and swir spectral shape and albedo as well as analyzing specific spectral features for mapping lithologic units in this weathered terrain

regional aeolian dynamics and sand mixing in the gran desierto evidence from landsat thematic mapper images spatial variations in sand composition were mapped on a regional scale in a terrestrial sand sea the gran desierto of sonora mexico mesoscale mapping on a satellite image base allowed quantitative interpretation of the dynamic development of sand sheets and dunes the results were used to interpret the quaternary geologic history of the tectonically active region at the mouth of the colorado river landsat thematic mapper multispectral images were used to predict the abundance of different mineralogies of sand grains in a mixed aeolian terrain a spectral mixing model separated the effects of vegetation and topographically induced shading and shadow from the effects produced by different mineral and rock types compositions determined remotely agreed well with samples from selected areas within the spectral limitations of the thematic mapper a simple discrimination capability for active versus inactive sand surfaces is demonstrated based upon differences in the percentage of low albedo accessory grains occurring on dormant aeolian surfaces a technique for discriminating between low albedo materials and macroscopic shade is implemented by combining thermal images with the results of the spectral mixing model the image analysis revealed important compositional variations over large areas that were not readily apparent in the field

an evaluation of short wave infrared swir data from the aviris and geoscan instruments for mineralogical mapping at cuprite nevada an evaluation was performed on swir 2000 2400 nm data from two airborne remote sensing systems for discriminating and identifying alteration minerals at cuprite nevada the data were acquired by the nasa airborne visible infrared imaging spectrometer aviris and the geoscan mk ii multispectral scanner the evaluation involved comparison of processed imagery and image derived spectra with existing alteration maps and laboratory spectra of rock samples from cuprite results indicate that both the aviris and geoscan data permit the discrimination of areas of alunite buddingtonite kaolinite and silicification using color composite images formed from three swir bands processed with either the decorrelation stretch or a log residual algorithm the laboratory spectral features of alunite kaolinite and buddingtonite could be seen clearly only in the log residual processed aviris data however this does not preclude their identification with the geoscan data

oceanic environmental changes on a shallow carbonate platform yangou jiangxi province south china during the permian triassic transition evidence from rare earth elements in conodont bioapatite abstract paleoceanic environmental stresses e g expanded anoxia elevated siliciclastic fluxes are thought to have been important factors in the latest permian mass extinction lpme here we investigate changes in redox conditions and siliciclastic fluxes during the permian triassic transition in south china through in situ analysis of the rare earth element ree composition of albid crowns of single conodont elements measured using laser ablation inductively coupled plasma mass spectrometry la icp ms for comparison we also analyzed rees in the sediment matrix enclosing the conodonts i e whole rock samples the study locale yangou was located on a shallow carbonate platform on the eastern margin of the yangtze platform to minimize the influence of detrital siliciclastics and thus enhance the chances of recovering a hydrogenous seawater sourced ree signal the analyzed conodonts exhibit ree patterns consistent with mixed hydrogenous seawater and lithogenous siliciclastic sources with specimens from below the lpme horizon showing dominantly hydrogenous influences y ho 50 and those from above the lpme horizon showing dominantly lithogenous influences y ho

chemical evolution of rare earth elements fractionation between colloidal and solution phases of filtered river water abstract within the dissolved fraction of connecticut river water there is large scale fractionation of rare earth elements between colloidal and solution phases colloidal particles carry a large part of the dissolved ree pool filtration through filters with progressively smaller pore size 0 45 0 22 and 0 025 m results in filtrates with lower absolute concentrations of ree and more fractionated compositions with decreasing pore size the filtrates have shale normalized abundances which become systematically more depleted in the lree relative to the hree hence both the solution and colloidal phases are significantly fractionated with respect to the dissolved fraction these conclusions are consistent with previous studies of ree in rivers estuaries and soils and with surface solution speciation models colloids play an important role in the aquatic geochemistry of rare earth elements they are responsible for the fractionation of ree during the estuarine removal of ree the removal of suspended and colloidal particles from river water leaves the solution phase of river water with compositions of ree as evolved as those of surface seawater hence the evolution of the composition of ree in river water and seawater is significantly influenced by colloid formation during chemical weathering on the continents

changes in the global carbon cycle occurred as two episodes during the permian triassic crisis coeval records of ocean atmosphere and terrestrial change are crucial to understanding the pattern and causes of global mass extinction across the permian triassic boundary ptb however relationships among changes in different settings remain largely unclear primarily due to the challenges associated with the correlation among disparate records here we compare marine carbon isotopic records with marine and terrestrial environmental and biotic events recorded in sediments from the meishan ptb section of south china time scaled carbonate carbon isotopes exhibit two gradual major shifts across the ptb at meishan and these are duplicable elsewhere around the tethys ocean the two shifts are associated with two episodes of enhanced terrestrial weathering indicated by an increased abundance of 13 c enriched moretanes relative to hopanes and an elevated abundance of black carbon fragments key marine events previously reported for the ptb including photic zone euxinia faunal mass extinction and cyanobacterial expansion also occur as two episodes coinciding with both of the progressive shifts to negative 13 c values and enhanced weathering the temporal sequence of the duplicable events suggests that the biotic crisis was a consequence of prolonged and episodic changes in the marine and continental systems and argues against an extraterrestrial impact as the main cause

remote sensing of geological structure in temperate agricultural terrains agricultural patterns dominate most remotely sensed images of lowland north europe and camouflage shadow patterns related to topography and hence to underlying geological structure images of those parts of the near infrared spectrum close to absorption features controlled by h o h bond stretching in plant cells and soil moisture largely remove this hindrance to interpretation if they are acquired at an early stage in the growing season the most easily available and most useful images of this type are those of band 5 from the landsat thematic mapper spatial filtering techniques applied to digital images can enhance them for structural interpretation if filter matrices and viewing scales are chosen to match the dimensions of the most common elements of the landscape and the peak of visual acuity filters to enhance directional attributes of an agricultural scene give appealing results but contain spurious linear features that masquerade as faults

sequencing events across the permian triassic boundary guryul ravine kashmir india abstract the permian triassic boundary ptb section at guryul ravine kashmir india comprises a 100 m thick apparently conformable succession of mixed siliciclastic carbonate sediments deposited in a deep shelf or ramp setting this section although long important in debates concerning placement of the ptb has not previously been the focus of an integrated chemostratigraphic study in the present study samples from a 20 m thick interval straddling the ptb were analyzed for major and trace element concentrations toc tic rees and organic 13c 15n to investigate contemporaneous environmental changes the guryul ravine section exhibits a sequence of discrete events that provide potentially important information about the character and cause s of the ptb two transient negative c isotopic excursions within the upper changxingensis zone predate the late permian event horizon lpeh i e the global mass extinction event by 200 400 kyr and are associated with the onset of a major eustatic rise and with secondary extinction peaks these excursions may record minor environmental disturbances prior to the main end permian crisis supporting an intrinsic mechanism such as volcanism and climate change rather than an extrinsic mechanism such as a bolide impact the onset of a large 4 0 to 4 5 sustained negative c isotope shift marks the lpeh which is located at the zewan khunamuh formation contact 260 cm below the biostratigraphically defined ptb the guryul ravine section exhibits a stepwise extinction pattern with the largest peak between the lpeh and ptb and a secondary peak just above the ptb a pattern similar to that observed in the meishan d gssp

exploring for a record of ancient martian life the immediate task facing exopaleontology is to define a strategy to explore mars for a fossil record during the decade long exploration program that lies ahead consideration of the quality of paleontological information preserved under different geological conditions is important if we are to develop a strategy with broad applicability the preservation of microbial fossils is strongly influenced by the physical chemical and biological factors of the environment which acting together determine the types of information that will be captured and retained in the rock record in detrital sedimentary systems preservation is favored by rapid burial in fine grained clay rich sediments in chemical sedimentary systems preservation is enhanced by rapid entombment in fine grained chemical precipitates for long term preservation host rocks must be composed of stable minerals that are resistant to chemical weathering and that form an impermeable matrix and closed chemical system to protect biosignatures from alteration during subsequent diagenesis or metamorphism in this context host rocks composed of highly ordered chemically stable mineral phases like silica e g cherts or phosphate e g phosphorites are especially favored such lithologies tend to have very long crustal residence times and along with carbonates and shales are the most common host rocks for the precambrian microfossil record on earth although we make the defensible assumption that mars was more like the earth early in its history clearly the geological and historical differences between the two planets are many such differences must be carefully considered when adapting an earth based strategy to mars

remote sensing a geophysical perspective in this review of developments in the field of remote sensing from a geophysical perspective the subject is limited to the electromagnetic spectrum from 0 4 mu m to 25 cm three broad energy categories are covered solar reflected thermal infrared and microwave the reflected solar region has been the most intensely studied photointerpretation of images from individual spectral bands or from color composites remains the most widely used method of analysis new instrumentation and digital processing based on analysis of laboratory and field spectra provide significant advances that are beginning to be applied to resource exploration color compositing techniques have been effectively used to detect the characteristic spectral reflectance features of iron oxides and hydroxyl bearing materials in satellite multispectral data for mapping areas of hydrothermal alteration airborne spectrometers can now detect individual spectral features of many minerals which are diagnostic of different stages of hydrothermal alteration evolution was from discrimination based on empirical experience to mineralogic identification and leading to quantification current developments also indicate new promising extensions to vegetated terrains advances in thermal infrared studies are due to development of thermal models that permit mapping of physical property variations and to detection of spectral differences that provide important compositional information analysis techniques are still in their infancy and thermal satellite data remain appropriate only for regional investigations microwave data have been acquired mainly with radar systems which can provide very high resolution from space but use of textural and slope information has had limited application long wavelength radiation has been shown to penetrate dry materials and this may be applicable in extremely arid regions

remote sensing for exploration an overview background material on measurement techniques and their physical basis as applied to rocks soils and vegetation new developments in high spectral resolution remote sensing for mineralogic and vegetation mapping modified journal abstract

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

relationships among vegetation climatic zonation soil and bedrock in the central white inyo range eastern california a ground based and remote sensing study to assess the effects of regional climate change using remote sensing methods we conducted integrated geologic botanical and field radiometer baseline studies on the ground in the central white inyo mountains vegetation on contrasting geologic substrates in 58 50 50 m sites was studied annually in early july and in late september 1997 2001 we quantified areal abundances of plant species by using field inventories and ground based values of the normalized difference vegetation index ndvi distributions and abundances of species are complex functions of microclimate elevation slope and facing direction seasonality soil development bedrock lithologies and albedo x ray diffraction studies demonstrate that the soils consist chiefly of in situ weathering components such as illite montmorillonite chlorite quartz carbonates and feldspars soils along higher ridges contain modest amounts of wind blown grains derived from glaciated granodioritic plutons and volcanic roof pendants of the sierra nevada light colored limestone and dolomite support only sparse amounts of sagebrush at any altitude whereas this drought tolerant species is widespread on dark argillite quartzite phyllite and granitic rocks grasses grow luxuriantly on dark granite and quartzite but poorly on carbonate bedrock trees are numerous on carbonate rocks but are uncommon on dark granite and quartzite higher albedo rocks and soils retain moisture better than darker substrates and in general support greater vegetative cover and biomass these studies provided ground control for hyperspectral data collected by er 2 aircraft along three airborne visible and infrared imaging spectrometer aviris flight lines because of the 16 m spatial resolution of the remotely sensed data only plant communities could be mapped from aviris imagery on the basis of the dominant species we identified the following communities shadscale desert scrub pinyon juniper woodlands sagebrush meadows mountain mahogany woodlands aspen woodlands bristlecone pine limber pine woodlands and alpine fell fields when judged by correlation with the 50 50 m ground based inventoried sites botanical community assignments for the june 2000 flight lines achieved an accuracy of 81 in contrast october 1996 assignments were only 65 correct reflecting low sun angle and senesced vegetation

weathering and global denudation a negative correlation between sediment yield and weathering history as measured by the chemical alteration cia of the suspended sediment is observed for many of the world s major rivers and other regions of denudation the weathering history is a first order control on the sediment yield of such areas termed equilibrium denudation regions for other areas data scatter with either apparent increases or decreases of sediment yield for given cia values these areas are termed nonequilibrium denudation regions low sediment yields can be attributed to moderated erosion either natural or human induced and or the incorporation of unweathered glacial debris accelerated erosion resulting in high sediment yield is primarily human induced and results from cultivation and other land use each of these effects has a profound influence on global sediment discharge from the continents pre human suspended sediment discharge from the continents is estimated to be 12 6 times 10 15 g yr or about 0 6 the

sediment mineralogy based on visible and near infrared reflectance spectroscopy visible and near infrared spectroscopy vnis can be used to measure reflectance spectra wavelength 350 2500 nm for sediment cores and samples a local ground truth cali bration of spectral features to mineral percentages is calculated by measuring reflectance spectra for a suite of samples of known mineralogy this approach has been tested on powders core plugs and split cores and we conclude that it works well on all three unless pore water is present initial vnis studies have concentrated on determination of relative proportions of carbonate opal smectite and illite in equatorial pacific sediments shipboard vnis based determination of these four components was demonstrated on ocean drilling program leg 199 rock colour is one of our oldest clues to com position and spectroscopy instruments now surpass the eye in providing quantitative compo sitional information the experimental technique is straightforward and non intrusive simply illu minate a rock surface record the spectrum of reflected light and extract any spectral responses that are sensitive to mineralogy reflectance spectroscopy can be used on powders core plugs and split cores and measurements take only seconds these advantages make the tech nique particularly attractive for depleted inter vals of core e g many basalts and for climate proxies requiring thousands of high resolution measurements

radioactive heat generation and its thermal effects in the alps apennines boundary zone abstract radioactive heat production data of rocks cropping out at the alps apennines boundary zone nw italy are presented samples were analysed in the laboratory by means of a gamma ray spectrometer they are representative of the savona unit and the ophiolitic sequences with metasediments and sediments of the voltri massif the sestri voltaggio zone and the lavagna nappe the heat production rate of sedimentary rocks ranges from 1 05 limestones to 2 52 w m 3 shales in ophiolites it varies from 0 04 serpentinites to 0 24 w m 3 metabasalts orthogneisses of the savona unit show the highest value 2 92 w m 3 potassium contributes to the heat generation on average by 17 in the metasedimentary and sedimentary rocks thorium contribution accounts on average by 43 except for dolomites in which 97 of the radioactive heat is produced by uranium calc schists shales radiolarites and phyllites give a th u ratio ranging from 3 to 4 that is very close to that of orthogneisses this ratio is lower in limestones almost all ophiolites and dolomites most rocks show a k th ratio ranging between 2 10 3 and 4 10 3 these data together with available thermal conductivity information are used in a finite element simulation to analyse the effects on the heat flux and temperature distribution due to lateral variation of thermal parameters changes in structure and composition of the uppermost part of the crust result in small wavelength variation of surface heat flux the low radioactive heat production of ophiolites produces a decrease of about 10 mw m 2 in the surface heat flux on the voltri massif

the comparative behaviors of yttrium and lanthanides in the seawater of the north pacific yttrium has long been recognized as an ekalanthanide because of its chemical contiguity relative to the chemistries of rare earth elements which are in recent years intensively utilized for elucidation of metal scavenging processes in the ocean here we present the first detailed depth profile of y iii in seawater together with the lanthanides in the north pacific ocean the concentrations of y iii range 70 290 pmol kg and show the nutrient like profile best resembling that of ho iii amongst the other rare earth elements the results agree well with an expectation based on the similarity in their ionic radii and hence stability constants of complexation with carbonate ions yet the ho iii y iii ratios in seawater systematically increase with depth suggesting that y and ho are fractionated during scavenging by natural marine particulates this is likely to result from the different complexation behavior in that y iii is more weakly complexed than ho iii with soft organic ligands on the surface of particulate matter during scavenging in the surface water but once released into seawater in the deep sea y iii is complexed with carbonate ions equally or stronger than ho the pattern of deep water enrichment in the lanthanide series appears to be consistent with the recent observation of partitioning between suspended particles and seawater our precise measurements also indicated that pr and tb best resemble nd and dy respectively in their oceanic behavior whereas ho and tm are intermediate between their neighboring rare earth elements

association of 34s depleted pyrite layers with negative carbonate δ13c excursions at the permian triassic boundary evidence for upwelling of sulfidic deep ocean water masses 1 a marine permian triassic boundary ptb section at nhi tao vietnam contains a series of at least 9 pyritic horizons characterized by concurrent decreases in pyrite s 34spy and carbonate c isotopic compositions 13ccarb the first and largest of the events that precipitated these pyritic horizons was coincident with the late permian mass extinction while subsequent events were generally smaller and occurred at quasiperiodic intervals of 20 to 30 ka a near complete lack of organic carbon to drive bacterial sulfate reduction in sediment pore waters among other considerations argues against a diagenetic control for these relationships rather the covariant patterns documented herein are most easily explained as the product of recurrent upwelling of anoxic deep ocean waters containing 34s depleted hydrogen sulfide and 13c depleted dissolved inorganic carbon the sulfide 34s record of the study section represents a mixture of a small amount of isotopically heavy authigenic pyrite formed via in situ bacterial sulfate reduction with a generally larger quantity of isotopically light syngenetic pyrite precipitated within the water column during upwelling episodes although upwelling of toxic deepwaters has been invoked in earlier studies as a mechanism for the late permian marine mass extinction this is the first study to 1 document patterns of pyrite 13ccarb covariation that strongly support upwelling as a major process at the ptb and 2 provide evidence of multiple quasiperiodic upwelling events that may reflect reinvigoration of global ocean overturn following a prolonged interval of late permian deep ocean stagnation

conodont u th he thermochronology initial results potential and problems abstract we performed he diffusion experiments and u th he age determinations on conodonts from a variety of locations to explore the potential of conodont u th he thermochronology to constrain thermal and exhumation histories of some sedimentary rock dominated terrains based on two diffusion experiments and age results from some specimens he diffusion in conodont elements appears to be similar to that in durango apatite fragments of similar size and closure temperatures are approximately 60 70 c for cooling rates of 10 c m y u th he ages of conodonts from some locations yield reproducible ages consistent with regional thermal history constraints and in at least two cases require a closure temperature lower than 80 c other samples however yield irreproducible ages and in one case yield ages much younger than expected based on regional geologic considerations these irreproducible samples show inverse correlations between parent nuclides and age consistent with late stage open system u th behavior

thrusting and faulting in metamorphic and sedimentary units of ligurian alps an example of integrated field work and geochemical analyses in a sector placed in the se part of the alps apennine junction a kilometre scale shear zone has been identified as the grognardo thrust zone gtz which caused the ne directed thrusting of metaophiolites voltri group and polymetamorphic continental crust slices valosio unit of ligurian alps onto oligocene sediments of an episutural basin known as tertiary piemonte basin the structural setting of the gtz is due to syn to late metamorphic deformation followed by a brittle thrusting that occurred in the late aquitanian times and can thus be related to one of the main contractional tectonic events suffered by northern apennines the gtz was then sealed by lower burdigalian carbonate platform sediments visone formation transtensive faulting followed in post burdigalian times along nw se regional faults and displaced the previously coupled sedimentary and metamorphic units the gtz thus underwent a plastic to brittle evolution during which carbonate rich fluids largely sustained the deformation in these stages a complex vein network originated within both the metamorphic and sedimentary rocks field data and stable isotopic analyses 13c and 18o of bulk rocks and veins show that fluid rock interaction caused the carbonatisation of the rocks in the late metamorphic stages and the cataclasis and recementation by the action of isochemical cold carbonate groundwater during the thrusting events carbonate veins largely developed also during the transtensive faulting stages with composition clearly different from that of the veins associated to thrust faults as indicated by the strong depletion in 13c of carbonate fillings suggesting the presence of exotic fluids characterised by a high content of organic matter

paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite abstract rare earth element concentrations in biogenic apatite of conodonts fish debris and inarticulate brachiopods were determined in over 200 samples from cambrian to modern sediments tests for experimental bias caused by the chemicals used to separate fossils from the rock matrix and for interlaboratory interexperiment or interspecies related variations clearly show that no resolvable fractionation of ree occurs incorporation of ree in biogenic apatite of recent fish debris occurs near the sediment water interface soon after deposition and reflects characteristics of seawater the original ree signature apparently survives subsequent burial and diagenesis cerium variations in fish debris from modern environments are controlled by redox potential ce is fractionated by co precipitation with metallic oxides under oxidizing conditions this fractionation produces a negative ce anomaly ce anom in seawater that is reflected in the sedimented fish debris conversely no fractionation of ce occurs under reducing conditions resulting in ce concentrations that are normal to enriched in anoxic seawater and fish debris deposited under local or basinwide anoxic conditions extrapolation of observations of the redox control of ce anom in modern oceans to fossil apatite indicates that anoxic conditions were prevalent in lower paleozoic and lower triassic oceans whereas in the upper paleozoic the world ocean was generally oxidizing

crystal chemical controls on rare earth element concentrations in fossil biogenic apatites and implications for paleoenvironmental reconstructions abstract fossil biogenic apatites display rare earth element ree patterns which have been proposed to reflect environmental and biological controls on past seawater composition these patterns can be separated in two groups 1 patterns that are similar to those of open ocean and epicontinental waters and 2 patterns that exhibit a strong enrichment in intermediate ree bell shaped patterns because ree trapping in biogenic apatites occurs mostly post mortem it is essential to understand the crystal chemical inorganic factors that can influence the fractionation of ree between apatite and water a model is proposed by which partition coefficients of ree between apatite and water for a substitution mechanism can be extrapolated from mineral melt partition data to seawater or sedimentary basin conditions these are compared with available experimental partition coefficients for ree adsorption mechanism and used to discuss ree patterns in fossil biogenic apatites calculations of ree patterns for apatites at equilibrium with water show that the bell shaped patterns in fossil apatites can be explained by fractionation with seawater or continental fluids at low temperature under crystal chemical control involving a substitution mechanism and in the context of extensive or late diagenesis in that case the equilibrium composition of the fluid cannot be unequivocally determined from observed ree concentrations in fossil apatites this type of sample is inappropriate to discuss the past environmental or biological controls on ree concentrations in the ocean other sample compositions suggest little to moderate alteration of the original oceanic to freshwater pattern through the adsorption mechanism in the context of weak or early diagenesis and may be used with caution for that purpose

temporal merging of remote sensing data to enhance spectral regolith lithological and alteration patterns for regional mineral exploration abstract remote sensing has been widely used to map geological structure regolith materials and hydrothermal alteration minerals in different regions of the world based largely on the spectral characteristics of clay carbonate and iron oxide minerals given that features related to minerals may form very subtle patterns in landsat imagery finding suitable methods for enhancing the spectral information due to alteration minerals has been the subject of much research since the satellites were launched although multispectral sensors such as landsat do not have enough spectral resolution to distinguish between specific minerals effective processing of the data does yield useful images for regional exploration and targeting when combined with a good understanding of the associated landforms aster and various airborne systems can now provide useful high resolution mineral information however the cost and time taken to acquire and process good resolution spectral data should now be balanced against the enhanced spectral discrimination possible using temporal merging or data stacking from the existing landsat data archive dating back to 1972 one critical characteristic of the spectra related to surface mineral composition is its persistence over time this study proposes a further enhancement to the data using temporal merging to create images that are both easier to interpret and more reliable indicators of lithology and alteration the new approach is to select a large number of scenes typically separated by two or more years and to merge the data for each band to give a cumulative spectral signature the technique of stacking landsat data to create a new dataset with much greater spectral depth is termed landsat tm3 or landsat tm temporal merge for terrain mapping this emphasises not only the process used to create the dataset but also the dominant use to which these data are ideally suited namely mapping geological and mineral related terrains

mapping hydrothermally altered rocks at cuprite nevada using the advanced spaceborne thermal emission and reflection radiometer aster a new satellite imaging system the advanced spaceborne thermal emission and reflection radiometer aster is a 14 band multispectral instrument on board the earth observing system eos terra the three bands between 0 52 and 0 86 m and the six bands from 1 60 and 2 43 m which have 15 and 30 m spatial resolution respectively were selected primarily for making remote mineralogical determinations the cuprite nevada mining district comprises two hydrothermal alteration centers where tertiary volcanic rocks have been hydrothermally altered mainly to bleached silicified rocks and opalized rocks with a marginal zone of limonitic argillized rocks country rocks are mainly cambrian phyllitic siltstone and limestone evaluation of an aster image of the cuprite district shows that spectral reflectance differences in the nine bands in the 0 52 to 2 43 m region provide a basis for identifying and mapping mineralogical components which characterize the main hydrothermal alteration zones opal is the spectrally dominant mineral in the silicified zone whereas alunite and kaolinite are dominant in the opalized zone in addition the distribution of unaltered country rocks was mapped because of the presence of spectrally dominant muscovite in the siltstone and calcite in limestone and the tuffaceous rocks and playa deposits were distinguishable due to their relatively flat spectra and weak absorption features at 2 33 and 2 20 m respectively an airborne visible infrared imaging spectrometer aviris image of the study area was processed using a similar methodology used with the aster data comparison of the aster and aviris results shows that the results are generally similar but the higher spectral resolution of aviris 224 bands permits identification of more individual minerals including certain polymorphs however aster has recorded images of more than 90 percent of the earth s land surface with less than 20 percent cloud cover and these data are available at nominal or no cost landsat tm images have a similar spatial resolution to aster images but tm has fewer bands which limits its usefulness for making mineral determinations

using precision temperature logs to estimate horizontal and vertical groundwater flow components a new method of estimating the horizontal and vertical specific discharge components of groundwater flow from precision subsurface temperature measurements is presented plotting the vertical temperature gradient as a function of both z and t and then fitting a plane to the data can provide coefficients from which the vertical and horizontal groundwater specific discharge components may be estimated alternatively by considering the vertical component of groundwater to be zero it is shown that quadric or cubic fits to temperature data provide coefficients from which horizontal groundwater flow may be estimated these expressions along with expressions previously derived to estimate only vertical only horizontal or both vertical and horizontal flow components are fitted to observational data from four sites and five flow zones it is learned for these examples using an available fitting program that although many of the expressions fit the observational data very well statistically those expressions which incorporate both the vertical and horizontal flow components of specific discharge must generally be constrained so that resulting parameters will provide flow estimates consistent in direction and heat transfer with available piezometer data and or the fundamental curvature of the temperature log expressions incorporating only x or only z can sometimes yield estimates quite different from the estimates obtained from the expressions incorporating both x and z it is concluded that an estimate of the horizontal and vertical flow components requires both consideration of the flow calculations along with available piezometric data and the fundamental curvature of the temperature log

influence of groundwater flow on the estimation of subsurface thermal parameters we investigated the influence of groundwater flow on the thermal tests performed in borehole heat exchangers to infer the underground thermal properties temperature time signals were simulated with a moving line source mls model under different hypotheses of darcy velocity periodic and random noise was included in the synthetic data obtained with this model in order to mimic high frequency disturbances caused by several possible sources e g equipment instability and changes in environmental conditions during the experiment that often occur in real signals the subsurface thermal conductivity the darcy velocity and the borehole thermal resistance were inferred by minimising the root mean square error between the synthetic dataset and the model the calculated thermal and hydraulic parameters were consistent with the a priori values the optimisation procedure results were then tested with the infinite line source ils model for a darcy velocity exceeding 10 7 m s 1 ils largely overestimates thermal conductivity the approach relying on the mls model was finally tested with real temperature time data and produced reliable estimates of thermal conductivity darcy velocity and borehole thermal resistance the inferred groundwater flow was cross checked by means of an independent method based on the analysis of temperature depth logs recorded under thermal equilibrium conditions such a test validates the darcy velocity inferred with the mls approach

climatic and biotic upheavals following the end permian mass extinction the recovery from the end permian mass extinction was slow and prolonged a temperature reconstruction shows that further biotic crises during the recovery were associated with extreme warmth

the incorporation of rare earth elements in modern coral we report measurements of rare earth elements rees which show that these trace elements are being incorporated in modern coral in proportion to their seawater concentrations four bermuda north rock coral species diploria strigosa diploria labyrinthiformis montastrea annularis and porites astreoides and two tarawa atoll samples of the species hydnophora microconos were analyzed by ti idms following cleaning techniques to isolate the lattice bound rees based on the replicate analyses of the same piece of diploria strigosa excellent reproducibility was achieved the ree ca ratios 0 1 3 nmol mol of the bermuda and tarawa corals are similar to those of cd ca the trace metal with the lowest seawater concentration used in coral studies with the exception of ce the distribution coefficients e g dnd nd coral nd seawater ca seawater ca coral between bermuda coral lattice and sargasso seawater have fairly flat patterns across the ree series the values of d range from 1 to 3 like those reported for other trace elements in corals this suggests but does not prove that rees are incorporated in the aragonite lattice of these corals the shale normalized ree patterns of the tarawa corals also have seawater like distributions however no local seawater data are available to calculate values of d two bermuda species d labyrinthiformis and p astreoides have values of d for ce that are high with respect to the d values of la and nd implying that there is preferential uptake of ce into the lattice this may be related to the fact that ce is the only ree with an active redox chemistry in seawater there is considerable interest in using the chemical and isotopic composition of coral as indicators of climatic variations the combination of ree ca ratios and neodymium isotopic composition of coral has the potential to help understand important natural processes a primary application could be directed toward a tracer for river water discharge in tropical regions and by inference a proxy for rainfall climate variation and weathering history this application would exploit the fractionated composition of rees in river water as a terrigenous signature in coastal corals

redox conditions in the end early triassic panthalassa abstract this study focuses on an upper lower triassic spathian to lowermost middle triassic anisian section representing the central panthalassic deep sea analysed organic carbon isotope ratio 13corg records from the section demonstrate that lower values in the spathian increase by up to 6 at the spathian anisian transition this trend accords with the carbonate carbon isotope 13ccarb record from shallow water carbonate sections most horizons during late spathian early anisian show features of redox conditions of not fully oxic but dysoxic conditions inferred from low mn u v mo and euhedral pyrite dominated occurrences conversely in the end spathian black coloured beds and underlying siliceous claystone beds relatively higher concentrations of redox sensitive elements such as u v mo and abundant pyrite framboids are detected as enrichment factors of redox sensitive elements are not much higher than the typical anoxic sulphidic trend and large pyrite framboids are found these trends suggest suboxic rather than strong anoxic conditions these oxygen poor conditions coincide with carbon isotope minimum values at the late spathian at the same time reducing seawater conditions have been also reported in from continental sections these coincidences imply global environmental perturbations that may have been related to the delayed recovery of life after the end permian mass extinction

evolution of oceanic redox conditions during the permo triassic transition evidence from deepwater radiolarian facies abstract the 90 biodiversity loss among marine invertebrate species during the end permian mass extinction the most severe phanerozoic biocrisis has been attributed to widespread oceanic anoxia superanoxia recent studies of the lithofacies inorganic geochemistry and biomarkers of permian triassic boundary ptb sections have yielded an inferred pattern of oceanic redox changes that is complex and sometimes inconsistent in this contribution we review the ecology of radiolarians an important microzooplankton group during the permo triassic transition and consider its implications for contemporaneous changes in paleoceanographic conditions our analysis shows that 1 late permian radiolarian faunas were cosmopolitan with different orders having specific depth preferences i e albaillellarians favoring deeper waters and spherical forms entactinarians and spumellarians shallower waters 2 deep water taxa declined earlier than shallow water taxa 3 many paleozoic type taxa survived into the early triassic but went extinct during a second crisis in the dienerian dead clade walking followed by the appearance or expansion of mesozoic type taxa during the olenekian and 4 the survival of paleozoic type taxa during the early triassic was greater at higher paleolatitudes than in the tropics these observations are consistent with a first order redox control on radiolarian faunal distributions specifically a shallowing and poleward expansion of the oceanic oxygen minimum zone during the ptb crisis the consequent adaptation of some deepwater taxa to shallower environments resulted in early triassic radiolarian faunas in continental basins becoming more similar to those in pelagic settings enhanced survival of paleozoic type taxa in high latitude regions indicates that the main stressor on permo triassic radiolarian communities was reduced oceanic oxygen levels stronger in the tropics rather than climatic warming stronger at the poles

diagenetic uptake of rare earth elements by bioapatite with an example from lower triassic conodonts of south china abstract the distribution patterns of rare earth elements rees are frequently used as proxies for ancient seawater chemistry or paleomarine environmental conditions however recent work has shown that diagenesis can lead to remobilization and inter elemental fractionation of rees and that these effects often occur in conjunction with redox reactions in sediment porewaters here we review existing literature on the diagenetic fluxes of rees in marine sediments and porewaters in order to systematize existing knowledge on this subject rees undergo significant redistribution among sediment phases during both early and late diagenesis as a consequence of adsorption and desorption processes remobilization of rees commonly leads to inter elemental fractionation variously leading to enrichment or depletion of the light middle or heavy ree fractions further ree remobilization can be facilitated by redox changes e g through reductive dissolution of host phases in suboxic and anoxic porewaters characteristic ree distribution patterns develop through these processes 1 a flat distribution signifying predominantly terrigenous siliciclastic influence 2 a middle ree bulge probably due to adsorption of light and heavy rees to mn and fe oxyhydroxides respectively and 3 heavy ree enrichment indicative of hydrogenous seawater influence note all patterns in this paper are normalized to the ree composition of average upper continental crust or ucc in the second part of this study we undertake an analysis of the ree distributions in conodonts and whole rock samples from west pingdingshan a permian triassic boundary section in south china using ree th and y ho ratios we show that almost all of the conodont samples have a strong diagenetic overprint and that the hydrogenous ree fraction is small and not isolatable furthermore the conodonts contain two diagenetic ree components one characterized by low ree 100 300 ppm high ree th ratios 1000 strong middle ree enrichment and eu eu ratios of 1 5 2 0 and the second by high ree 300 2000 ppm low ree th ratios 20 30 little or no middle ree enrichment and eu eu ratios of 1 0 the first component exhibits a pronounced middle ree bulge that represents an early diagenetic signature associated with suboxic conditions possibly related to adsorption of rees onto fe mn oxyhydroxides in the shallow subsurface environment the second component shows a flat ree distribution that is similar to both our whole rock samples and average ucc indicating derivation from rees released from detrital siliciclastics e g clay minerals probably at a range of burial depths from shallow to deep failure of the conodont samples to yield an isolatable hydrogenous component demonstrates that bioapatite does not always preserve a primary marine ree signature given that bioapatite rees have been widely used for this purpose often on the assumption of minimal or no diagenetic influence our findings are likely to necessitate a re evaluation of the results of many earlier studies in general we counsel caution in inferring a hydrogenous origin for rees in bioapatite owing to frequent diagenetic alteration of ree distributions

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

terrestrial marine teleconnections in the collapse and rebuilding of early triassic marine ecosystems abstract the latest permian mass extinction lpe just prior to the permian triassic boundary at 252 ma resulted in the disappearance of 90 of skeletonized marine taxa and the replacement of the paleozoic fauna by the modern fauna in the immediate aftermath of the extinction shallow marine ecosystems were dominated by microbial communities and diminutive disaster taxa lilliput faunas and the post crisis period in general was characterized by high abundance low diversity marine communities occupying a reduced ecological space the recovery of marine ecosystems was a protracted process lasting throughout the 5 myr long early triassic some clades failed to recover and subsequently went extinct dead clades walking while others recovered only to suffer secondary crises during the early triassic profound environmental changes accompanied these biotic developments deep oceans experienced sustained hypoxia or anoxia for at least several million years following the boundary event anoxia was also widespread in shallow marine areas especially at the time of the lpe but it was more episodic and abated more rapidly than in the deep ocean making it an unlikely factor in the delayed recovery of early triassic marine ecosystems the development of anoxia was due at least in part to a sharp temperature rise following the lpe but may have been stimulated by changes in marine nutrient inventories and productivity rates as well these conditions may have been the result of a concurrent increase in subaerial weathering rates that was sustained into the early triassic in addition to increasing nutrient fluxes to marine areas rapid weathering caused a massive influx of sediment to shallow marine systems subjecting marine biotas to siltation stress this scenario implies close teleconnections between terrestrial and marine environments during the permian triassic boundary crisis with perturbations of the terrestrial realm contributing to the marine crisis

rare earth elements in old biogenic apatites abstract the ree distributions in individual upper devonian conodonts have been measured by ion probe the patterns of all analyzed conodonts are enriched in middle ree eu gd and have a weak or no ce anomaly concentrations and la yb or la sm ratios vary very little within or among individuals from the same zone which suggests that uptake of labile ree from sediments was essentially quantitative therefore the ree signature of the primary carriers probably organic and oxyhydroxides particulates from marine suspensions was efficiently transferred to biogenic apatites and survived late diagenetic processes ree patterns of conodonts do not resemble those of present day seawater and post cretaceous biogenic phosphates which are typically depleted in nd and sm with a negative ce anomaly since ree distributions in the modern water column mimic those of nutrients we assume that in pre cretaceous seawater they were not controlled by surface biological activity we assume instead that ree in pre cretaceous seawater can be explained by mechanism of desorption adsorption on particle surfaces progressive extraction of lree from river water by oxyhydroxides leads to precipitates enriched in middle ree a simple quantitative model was calculated in order to illustrate the proposed mechanism

pyrite framboids in the permian triassic boundary section at meishan china evidence for dysoxic deposition pyrite framboid evidence from the permian triassic global stratotype at meishan china indicates the late permian mass extinction is closely associated with a dramatic decline of benthic oxygen levels sizes and abundances of the framboids were determined from acid residues and in situ on polished sections of the samples the framboids are abundant in the thin pyrite lamina on the top of bed 24e the upper layer of bed 24 and beds 25 26 and 29 rare in bed 24e and bed 28 but absent in bed 27 they have narrow size distributions with average diameters from 4 6 mu m to 8 7 mu m which are similar to those formed under anoxic dysoxic conditions the abundances and mean diameters of the pyrite framboids indicate redox conditions of deposition changing from upper dysoxia bed 24e and lower dysoxia pyrite lamina beds 25 and 26 to oxygenation bed 27 and again to upper dysoxia bed 28 and lower dysoxia bed 29 our discovery confirms a worldwide dysoxic marine event during the permian triassic transition suggestive of a direct relationship with the permian triassic marine mass extinction c 2007 elsevier b v all rights reserved

remote sensing detection of heavy oil through spectral enhancement techniques in the western slope zone of songliao basin china landsat 7 enhanced thematic mapper plus etm imagery was used to identify anomalous areas caused by hydrocarbon leakage in fula erji in the western slope of songliao basin china three image enhancement techniques including principal component analysis pca band ratioing and false color composition fcc were used based on the spectral characteristics of hydrocarbon induced minerals and the eigenvectors of pca the best four principal components pcs 1345 pc3 the third component of the pca on bands 1 3 4 and 5 1357 pc3 3457 pc4 and 123457 pc4 were selected for fcc combined with band ratios of 3 1 4 3 and 7 5 according to the tonal characteristics of the surface near wells and their visual expression four fcc images were acquired for hydrocarbon induced area delineation the result indicates that anomalies are expressed as a faint tone blob and are mostly located in the holocene sediments an analysis of two cross sections traversing the identified anomalies suggests that they are closely related to the anomalous area interpreted from the four fcc images field data of magnetic susceptibility and delta carbonate are consistent with the distribution of the tonal anomalies and suggest a positive spatial association between the identified anomalous area and the hydrocarbon leakage environment

interactive processing of satellite images for structural and lithological mapping in northeast africa interactive digital processing of multispectral satellite images landsat mss using principal components transformations and spatial filtering has clarified the position of continuous sutures linking apparently isolated pan african late proterozoic ophiolites these have been field checked and an arrangement of pan african suture zones is proposed spatial filtering has also highlighted faults with various trends which can be related to the late precambrian tectonics of the horn of africa region

distribution of hydrothermally altered rocks in the reko diq pakistan mineralized area based on spectral analysis of aster data abstract the reko diq pakistan mineralized study area approximately 10 km in diameter is underlain by a central zone of hydrothermally altered rocks associated with cu au mineralization the surrounding country rocks are a variable mixture of unaltered volcanic rocks fluvial deposits and eolian quartz sand analysis of 15 band advanced spaceborne thermal emission and reflection radiometer aster data of the study area aided by laboratory spectral reflectance and spectral emittance measurements of field samples shows that phyllically altered rocks are laterally extensive and contain localized areas of argillically altered rocks in the visible through shortwave infrared vnir swir phyllically altered rocks are characterized by al oh absorption in aster band 6 because of molecular vibrations in muscovite whereas argillically altered rocks have an absorption feature in band 5 resulting from alunite propylitically altered rocks form a peripheral zone and are present in scattered exposures within the main altered area chlorite and muscovite cause distinctive absorption features at 2 33 and 2 20 m respectively although less intense 2 33 m absorption is also present in image spectra of country rocks important complementary lithologic information was derived by analysis of the spectral emittance data in the 5 thermal infrared tir bands silicified rocks were not distinguished in the 9 vnir swir bands because of the lack of diagnostic spectral absorption features in quartz in this wavelength region quartz bearing surficial deposits as well as hydrothermally silicified rocks were mapped in the tir bands by using a band 13 band 12 ratio image which is sensitive to the intensity of the quartz reststrahlen feature improved distinction between the quartzose surficial deposits and silicified bedrock was achieved by using matched filter processing with tir image spectra for reference

emission spectroscopy of clay minerals and evidence for poorly crystalline aluminosilicates on mars from thermal emission spectrometer data 1 to understand the aqueous history of mars it is critical to constrain the alteration mineralogy of the martian surface previously published analyses of thermal infrared 6 25 m remote sensing data of mars suggest that dark regions have 15 20 clay minerals however near infrared 1 3 m spectral results generally do not identify widespread clay minerals thermal infrared detections of clays on mars are difficult to interpret owing in part to the relative paucity of published spectral analyses of clay minerals and clay bearing materials using similar spectra thermal infrared emission spectra in this study we present an analysis of the thermal emission spectral features 6 25 m or 400 1650 cm 1 of a suite of clay mineral reference materials and clay bearing rocks linking their spectral features to the crystal chemical properties of the clays on the basis of this context provided by the emission spectral analysis of clay minerals and clay bearing rocks we reconsider the evidence for clay minerals on mars from thermal emission spectrometer tes results we propose that global scale clay abundances determined from tes probably represent a geologically significant surface component though they may actually correspond to poorly crystalline aluminosilicates with similar si o ratios to clay minerals 0 3 0 4 rather than well crystalline clays if clay minerals or clay like materials on mars are poorly crystalline and or dessicated they may be detectable in the thermal infrared but not easily detected with near infrared data sets

inferring hydro geothermal parameters from advectively perturbed thermal logs we present techniques to infer thermo hydraulic parameters from the analysis of underground temperature data from boreholes two different cases are analyzed thermal data from artesian wells and from boreholes drilled in unconfined aquifers the former allow the assessment of the formation temperature gradient and the flow volume the latter give estimates of the darcy velocity and consequently allow the inference of the aquifer hydraulic conductivity the analysis procedure consists in matching thermal logs with analytical models incorporating both heat and mass transfer the thermo hydraulic parameters are obtained from the coefficients of the advective models by means of the least square fitting method examples of applications are given for a set of temperature logs from a geothermal area of northwestern italy preliminarily thermal gradients and the correction for the recent climate change were evaluated from thermal data of boreholes with no evidence of advection the analysis of artesian boreholes gave high formation thermal gradients in agreement with those obtained from boreholes with dominant conductive thermal regime in boreholes drilled in permeable formations the models predicting the temperature versus depth distribution resulted generally less sensitive to geological noise and fitted the field data better than the models based on the gradient analysis if the shape of the thermal profile is taken into account as a qualitative descriptor of the type of flow reliable estimates of the flow components can be obtained

bioessential element depleted ocean following the euxinic maximum of the end permian mass extinction abstract we describe variations in trace element compositions that occurred on the deep seafloor of palaeo superocean panthalassa during the end permian mass extinction based on samples of sedimentary rock from one of the most continuous permian triassic boundary sections of the pelagic deep sea exposed in north eastern japan our measurements revealed low manganese mn enrichment factor normalised by the composition of the average upper continental crust and high cerium anomaly values throughout the section suggesting that a reducing condition already existed in the depositional environment in the changhsingian late permian other redox sensitive trace element vanadium v chromium cr molybdenum mo and uranium u enrichment factors provide a detailed redox history ranging from the upper permian to the end of the permian a single v increase representing the first reduction state of a two step v reduction process detected in uppermost changhsingian chert beds suggests development into a mildly reducing deep sea condition less than 1 million years before the end permian mass extinction subsequently a more reducing condition inferred from increases in cr v and mo developed in overlying changhsingian grey siliceous claystone beds the most reducing sulphidic condition is recognised by the highest peaks of mo and v second reduction state in the uppermost siliceous claystone and overlying lowermost black claystone beds in accordance with the end permian mass extinction event this significant increase in mo in the upper changhsingian led to a high mo u ratio much larger than that of modern sulphidic ocean regions this trend suggests that sulphidic water conditions developed both at the sediment water interface and in the water column above the end permian mass extinction horizon mo v and cr decrease significantly on this trend we provide an interpretation of drawdown of these elements in seawater after the massive element precipitation event during the end permian maximum development of the reducing water column a decrease in the mo u ratio despite enrichment of mo and u also supports that of mo calculations of the total amounts of these elements precipitated compared with the global seawater inventory suggest that when more than 6 10 of the global ocean became euxinic as much as the study section most of the dissolved elements would precipitate into sediments resulting in a global element depleted seawater condition mo v and cr act as bioessential elements for both primary producers and animals the continuing reducing water column and the lack of bioessential elements could have had a considerable effect on primary producer turnover and marine life metabolism not only in the pelagic environment but also in surrounding marine environments

rare earth element cycling in the pore waters of the bering sea slope iodp exp 323 abstract we studied the diagenetic behavior of rare earth elements rees in a highly productive passive margin setting of the bering sea slope site u1345 was drilled during the integrated ocean drilling program expedition 323 at a water depth of 1008 m currently in the center of an oxygen minimum zone pore water concentrations of fourteen rees were determined down to 140 meters below the seafloor mbsf the ree concentrations were higher in the pore water than the deep seawater indicating that there was significant liberation from the sediments during diagenesis there was a major peak at 10 mbsf that was more pronounced for the heavy ree hree this peak occurred below the sulfate methane transition zone 6 3 mbsf and coincided with high concentrations of dissolved iron and manganese at 2 mbsf there was a minor peak in ree and mn contents below 40 mbsf the ree concentration profiles remained constant the ce anomaly was insignificant and relatively constant paas normalized ce ce 1 1 0 2 throughout the depth profile showing that the ce depleted in seawater was restored in the pore water hree enrichment was observed over the entire 140 m except for the upper 1 m where a middle ree mree bulge was apparent ree release in shallow depths 2 4 mbsf is attributed to the release of light rees lrees and mrees during the organoclastic reduction of mn oxides in anoxic sediments the high hree concentrations observed at 10 mbsf can be attributed to the reduction of fe and mn minerals tied to anaerobic oxidation of methane or less significantly to ferromagnesian silicate mineral weathering the upward diffusion flux across the sediment water interface was between 3 for tm and 290 for ce pmol m 2 y 1

fluctuations of redox conditions across the permian triassic boundary new evidence from the gssp section in meishan of south china abstract oceanic anoxia has long been considered as one of the main causes for the end permian mass extinction however the results obtained by different researchers are rather divergent from different sections or even on the same section using the same redox proxy this study aims to examine the causes for some of these divergent results using high resolution pyrite framboid sampling at the meishan gssp section in south china detailed microfacies analysis shows that the uppermost late permian strata comprises two significantly different sedimentary facies one characterized by silicious muddy limestone and recognized as representing autochthonous background sediments the other distinguished by bioclastic grainstone interpreted to be allochthonous in origin and have been transported from the nearby platform margin these two different sedimentary facies represent two distinctly different redox conditions together with the facies analysis a statistical analysis of pyrite framboids was carried out to evaluate the redox evolution across the permian triassic boundary abundant framboids with average diameters of about 6 m are found in background sediments beneath the extinction boundary indicating generally anoxic bottom water conditions but this condition was punctuated by transient intervals of rapid oxygenation interpreted to have been caused by intrusion of intermittent turbidity flows our study also showed that anoxic conditions persisted into the immediate aftermath of the mass extinction thereafter it was quickly followed by a relatively long period of oxic conditions with rare framboids however the redox conditions returned to anoxia with abundant pyrite framboids averaging about 5 m in diameter accompanied by a rapid global transgression the oxygenation manifested near the permian triassic boundary coincides with the negative excursion of carbon isotope this would imply that contrary to previous interpretations this great 13c negative excursion was probably not caused by the upwelling of anoxic deep ocean waters

groundwater flow analysis using different geothermal constraints the case study of acqui terme area northwestern italy abstract we review some analytical techniques that use underground thermal data as tracers of groundwater flow these techniques allow the evaluation of the darcy velocity in shallow aquifers of mid low permeability and the evaluation of heat gain loss by conduction in deeper aquifers examples of application are then given for the acqui terme hydrothermal system located in the tertiary piedmont basin northwestern italy the analysis of borehole temperatures allowed the inference of the hydraulic features of the sedimentary cover of the hydrothermal system the results show the presence of a relatively weak flow with upward and horizontal components only in conglomerates occurring at the base of the marly impermeable cover the analysis of the heat transported in the deep parts of the hydrothermal system was approached by splitting the water path into different sections each with given shape slope and hydraulic properties the recharge area is situated in the upland south of the discharge area meteoric water initially descends and then flows horizontally within the fractured metamorphic basement of the basin heating by conduction finally from a reservoir positioned at intermediate depths hot water reaches rapidly the surface through a sub vertical fault this scheme of deep water flow is constrained by the regional surface heat flow and the local geothermal gradient and it is consistent with data of rock water equilibrium temperature

paleoredox biotic and sulfur isotopic changes associated with the end permian mass extinction in the western tethys abstract detailed cm scale s toc total organic carbon 34ssulfide and pyrite morphological analysis of the permian triassic boundary beds at the bulla section northern italy suggests that marine waters at this site saw the influx of two dysoxic euxinic intervals that mark the end permian extinction event this suggests reduced oxygen conditions and the presence of h2s is the cause of the end permian extinction the bulla section also shows three troughs in 34ssulfate of which the latter two coincide with the dysoxic euxinic intervals this suggests that the latter two 34ssulfate troughs are the result of h2s oxidation in surface waters but the first trough is the result of a different mechanism we propose that h2s was oxidized in another region either to low 34ssulfate water or elemental s which then moved to the bulla area at the balvany section hungary there are two 34ssulfate troughs near the extinction and no evidence of euxinia a similar mechanism to the first bulla 34ssulfate trough is proposed with the suggestion that these waters were also depleted in oxygen in order to effect the extinction at balvany

the geochemical behavior and isotopic composition of hg in a mid pleistocene western mediterranean sapropel abstract the concentrations of mercury hg and other trace metals ni cu zn mo ba re u and the hg isotopic composition were examined across a dramatic redox and productivity transition in a mid pleistocene mediterranean sea sapropel sequence characteristic trace metal enrichment in organic rich layers was observed with organic rich sapropel layers ranging in hg concentration from 314 to 488 ng g avg 385 with an average enrichment in hg by a factor of 5 9 compared to organic poor background sediments which range from 39 to 94 ng g hg avg 66 comparison of seawater concentrations and sapropel accumulations of trace metals suggests that organic matter quantitatively delivers hg to the seafloor near complete scavenging of hg from the water column renders the sapropel hg isotopic composition representative of mid pleistocene mediterranean seawater sapropels have an average 202hg value of 0 91 0 15 n 5 1 sd and 199hg value of 0 11 0 03 n 5 1 sd background sediments have an average 202hg of 0 76 0 16 n 5 1 sd and 199hg of 0 05 0 01 n 5 1 sd which is indistinguishable from the sapropel values we suggest that the sapropel isotopic composition is most representative of the mid pleistocene tyrrhenian sea

complete biotic and sedimentary records of the permian triassic transition from meishan section south china ecologically assessing mass extinction and its aftermath abstract the meishan section south china is the global stratotype section and point gssp for the permian triassic boundary ptb and is also well known for the best record demonstrating the permian triassic mass extinction ptme all over the world this section has also been studied using multidisciplinary approaches to reveal the possible causes for the greatest phanerozoic biocrisis of life on earth many important scenarios interpreting the great dying have been proposed on the basis of data from meishan nevertheless debates on biotic extinction patterns and possible killers still continue this paper reviews all fossil and sedimentary records from the permo triassic p tr transition based on previously published data and our newly obtained data from meishan and assesses ecologically the ptme and its aftermath to determine the biotic response to climatic and environmental extremes associated with the biocrisis eight updated conodont zones clarkina yini clarkina meishanensis hindeodus changxingensis clarkina taylorae hindeodus parvus isarcicella staeschei isarcicella isarcica and clarkina planata zones are proposed for the ptb beds at meishan major turnover in fossil fragment contents and ichnodiversity occurs across the boundary between bed 24e 5 and bed 24e 6 suggesting an extinction horizon in a thin stratigraphic interval the irregular surface in the middle of bed 27 is re interpreted as a firmground of glossifungites ichnofacies rather than the previously proposed submarine dissolution surface or hardground surface both fossil fragment contents and ichnodiversity underwent dramatic declines in beds 25 26a coinciding with metazoan mass extinction fossil fragment content ichnodiversity and all ichnofabric proxies including burrow size tiering level bioturbation level indicate that the p tr ecologic crisis comprises two discrete stages coinciding with the first and second phases of the ptme in meishan ecologic crisis lagged behind biodiversity decline during the ptme pyrite framboid size variations suggest that depositional redox condition was anoxic to euxinic in the latest changhsingian became euxinic in beds 25 26a turned dysoxic in bed 27 then varied from euxinic to anoxic through most of the griesbachian the 9 c increase in seawater surface temperature from bed 24e to bed 27 at meishan seems to result in dramatic declines in biodiversity and fossil fragment contents in beds 25 26a but had little effect on all ecologic proxies both metazoans and infauna seem not to have been affected by the pre extinction anoxic euxinic condition the anoxic event associated with the ptme may have occurred in a much shorter period than previously thought and is only recorded in beds 25 26a at meishan fossil fragment contents ichnofaunas ichnofabrics and pyrite framboid size all show that no signs of oceanic acidification and anoxia existed in bed 27 the early griesbachian anoxia may have resulted in rarity of ichnofauna and metazoans in the lower yinkeng formation in which the ichnofauna is characterized by small simple horizontal burrows of planolites and metazoan faunas are characterized by low diversity high abundance opportunist dominated communities the rapid increase of 9 c in sea surface temperature and a short anoxia or acidification coincided with the first pulse biocrisis while a prolonged and widespread anoxia probably due to a long period of high seawater temperate condition may be crucial in mortality of most organisms in the second pulse ptme marine ecosystems started to recover coupled with environmental amelioration in the late griesbachian