mineralogy and geochemistry of alluvium contaminated by metal mining in the rio tinto area southwest spain the rio tinto in sw spain drains cu and pyrite mines which have been in operation since at least the bronze age extensive metal mining especially from 1873 to 1954 has resulted in contamination of the rio tinto alluvium with as cu pb ag and zn x ray diffraction xrd wavelength dispersive x ray mapping scanning electron microscope petrography and x ray energy dispersive edx analysis has revealed that 4 major groups of contaminant metal and as bearing minerals including sulphides fe as oxides fe oxides hydroxides oxyhydroxides and fe oxyhydroxysulphates occur in the alluvium sulphide minerals including pyrite chalcopyrite arsenopyrite and sphalerite occur in alluvium near the mining areas iron hydroxides and oxyhydroxides such as goethite and possibly ferrihydrite occur in cements in both the mining areas and alluvium downstream and carry minor amounts of as cu and zn iron oxyhydroxysulphates including jarosite plumbojarosite and possibly schwertmannite are the most common minerals in alluvium downstream of the mining areas and are major hosts of cu pb zn and of as next to the fe as minerals this work and other field observations suggest that 1 the extreme acidity and elevated metal concentrations of the river water will probably be maintained for some time due to oxidation of pyrite and other sulphides in the alluvium and mine waste tips and from formation of secondary oxide and oxyhydroxysulphates 2 soluble fe oxyhydroxysulphates such as copiapite which form on the alluvium are a temporary store of contaminant metals but are dissolved during periods of high rainfall or flooding releasing contaminants to the aqueous system 3 relatively insoluble fe oxyhydroxysulphates and hydroxides such as jarosite and goethite may be the major long term store of alluvial contaminant metals and 4 raising river ph will probably cause precipitation of fe oxyhydroxides and oxides hydroxides oxyhydroxides and thus have a positive effect on water quality but this action may destabilise some of these contaminant metal bearing minerals releasing metals back to the aqueous system

spirit mars rover mission to the columbia hills gusev crater mission overview and selected results from the cumberland ridge to home plate this paper summarizes the spirit rover operations in the columbia hills of gusev crater from sols 513 to 1476 and provides an overview of selected findings that focus on synergistic use of the athena payload and comparisons to orbital data results include discovery of outcrops voltaire on husband hill that are interpreted to be altered impact melt deposits that incorporated local materials during emplacement evidence for extensive volcanic activity and aqueous alteration in the inner basin is also detailed including discovery and characterization of accretionary lapilli and formation of sulfate silica and hematite rich deposits use of spirit s data to understand the range of spectral signatures observed over the columbia hills by the mars reconnaissance orbiter s compact reconnaissance imaging spectrometer crism hyperspectral imager 0 4 4 m is summarized we show that crism spectra are controlled by the proportion of ferric rich dust to ferrous bearing igneous minerals exposed in ripples and other wind blown deposits the evidence for aqueous alteration derived from spirit s data is associated with outcrops that are too small to be detected from orbital observations or with materials exposed from the shallow subsurface during rover activities although orbital observations show many other locations on mars with evidence for minerals formed or altered in an aqueous environment spirit s data imply that the older crust of mars has been altered even more extensively than evident from orbital data this result greatly increases the potential that the surface or shallow subsurface was once a habitable regime

veneers rinds and fracture fills relatively late alteration of sedimentary rocks at meridiani planum mars veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at meridiani planum mars the chemistry of submillimeter thick buff colored veneers reflects multiple processes at work since the establishment of the current plains surface veneer composition is dominated by the mixing of silicate rich dust and sulfate rich outcrop surface but it has also been influenced by mineral precipitation including nacl and possibly by limited physical or chemical weathering of sulfate minerals competing processes of chemical alteration perhaps mediated by thin films of water or water vapor beneath blanketing soils and sandblasting of exposed outcrop surfaces determine the current distribution of veneers dark toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture halite precipitation and possible minor sulfate removal cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact these appear to reflect limited groundwater activity along the margins of fractures cementing mechanically introduced fill derived principally from outcrop rocks the limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping meridiani strata were exposed on the plains surface

discovery of jarosite within the mawrth vallis region of mars implications for the geologic history of the region abstract analysis of visible to near infrared reflectance data from the mro crism hyperspectral imager has revealed the presence of an ovoid shaped landform approximately 3 by 5 km in size within the layered terrains surrounding the mawrth vallis outflow channel this feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite specifically a k bearing jarosite kfe3 so4 2 oh 6 terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur previously identified phyllosilicates in the mawrth vallis layered terrains include a basal sequence of layers containing fe mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates in terms of its fine scale morphology revealed by mro hirise imagery the jarosite bearing unit has fracture patterns very similar to that observed in fe mg smectite bearing layers but unlike that observed in the al bearing phyllosilicate unit the ovoid shaped landform is situated in an east west bowl shaped depression superposed on a north sloping surface spectra of the ovoid shaped jarosite bearing landform also display an anomalously high 600 nm shoulder which may be consistent with the presence of goethite and a 1 92 m absorption which could indicate the presence of ferrihydrite goethite jarosite and ferrihydrite can be co precipitated and or form through transformation of schwertmannite both processes generally occurring under low ph conditions ph 2 4 to date this location appears to be unique in the mawrth vallis region and could represent precipitation of jarosite in acidic sulfur rich ponded water during the waning stages of drying

hydrated silicate minerals on mars observed by the mars reconnaissance orbiter crism instrument phyllosilicates a class of hydrous mineral first definitively identified on mars by the omega observatoire pour la mineralogie l eau les glaces et l activitie instrument preserve a record of the interaction of water with rocks on mars global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy fe mg and al smectite clays this was interpreted to indicate that phyllosilicate formation occurred during the noachian the earliest geological era of mars and that the conditions necessary for phyllosilicate formation moderate to high ph and high water activity were specific to surface environments during the earliest era of mars s history here we report results from the compact reconnaissance imaging spectrometer for mars crism of phyllosilicate rich regions we expand the diversity of phyllosilicate mineralogy with the identification of kaolinite chlorite and illite or muscovite and a new class of hydrated silicate hydrated silica we observe diverse fe mg oh phyllosilicates and find that smectites such as nontronite and saponite are the most common but chlorites are also present in some locations stratigraphic relationships in the nili fossae region show olivine rich materials overlying phyllosilicate bearing units indicating the cessation of aqueous alteration before emplacement of the olivine bearing unit hundreds of detections of fe mg phyllosilicate in rims ejecta and central peaks of craters in the southern highland noachian cratered terrain indicate excavation of altered crust from depth we also find phyllosilicate in sedimentary deposits clearly laid by water these results point to a rich diversity of noachian environments conducive to habitability

geochemistry of shales from the archean 3 0 ga buhwa greenstone belt zimbabwe implications for provenance and source area weathering abstract phyllites from the archean 3 0 ga buhwa greenstone belt zimbabwe were deposited on a stable cratonic platform analyses of the phyllites generally define a single geochemical group based on major and trace element abundances the phyllites are strongly depleted in cao na2o and sr with respect to average archean upper crust by contrast k2o ba and rb are enriched several times relative to average archean upper crust reflecting basin scale k metasomatism transition metals are somewhat depleted whereas high field strength elements are typically enriched relative to average archean upper crust samples generally have fractionated lree patterns average cen smn 2 4 with small negative eu anomalies average eu eu 0 78 and generally flat hrees average gdn ybn 1 3 such geochemical characteristics suggest that the source dominantly consisted of tonalite with less common occurrences mafic volcanic rocks and granite mixing calculations which massbalance the rees and th sc suggest 70 tonalite 15 mafic volcanic rocks and 15 granite as possible proportions for the source of the phyllites a nearby early archean 3 5 ga continental nucleus preserves similar lithologies and is the probable source intense chemical weathering of the source terrane is indicated by premetasomatized chemical index of alteration values of 95 100 nearly complete depletion of cao and na2o and high al2o3 na2o ratios fine grained sediments of comparable age and presumed tectonic setting elsewhere in southern africa show similar geochemical characteristics implying that source area compositions and weathering intensities were similar these mature platformal deposits suggest a tectonically stable environment where intense chemical weathering took place at 3 0 ga across southern africa

volcanic source for fixed nitrogen in the early earth s atmosphere hot volcanic vents promote the thermal fixation of atmospheric n2 into biologically available forms the importance of this process for the global nitrogen cycle is poorly understood at masaya volcano nicaragua no and no2 are intimately associated with volcanic aerosol such that nox levels reach as much as an order of magnitude above local background in plume hno3 concentrations are elevated above background to an even greater extent 50 mmol m 23 we estimate the production efficiency of fixed nitrogen at hot vents to be 3 3 10 28 mol j 21 implying present day global production of 10 9 mol of fixed n per year although conversion efficiency would have been lower in a preoxygenated atmosphere we suggest that subaerial volcanoes potentially constituted an important source of fixed nitrogen in the early earth producing as much as 10 11 mol yr 21 of fixed n during major episodes of volcanism these fluxes are comparable to estimated nitrogen fixation rates in the prebiotic earth from other major sources such as bolide impacts and thunderstorm and volcanic lightning

hydrothermal jarosite and hematite in a pyroxene hosted melt inclusion in martian meteorite miller range mil 03346 implications for magmatic hydrothermal fluids on mars low temperature aqueous processes have been implicated in the generation of jarosite and hematite on the martian surface but little is known regarding the role that high temperature magmatic fluids may have played in producing similar assemblages on mars we have identified jarosite and hematite in a clinopyroxene hosted melt inclusion in martian meteorite mil 03346 that shows evidence of having been hydrothermally precipitated in addition to jarosite and hematite the melt inclusion contains titanomagnetite pyrrhotite potassic chlorohastingsite an iron rich silicate glass and possibly goethite these phases were identified and characterized using scanning electron microscopy sem con focal raman spectroscopy and electron probe microanalysis epma based on observed textural relationships and the compositions of the hosted phases we report that the jarosite bearing melt inclusion in mil 03346 has recorded a fluid rich history that began in the magmatic stage and continued to low temperatures this history begins at entrapment of a volatile rich silicate melt that likely reached fluid saturation after only minor crystallization within the melt inclusion this fluid rich in chlorine reacted with surrounding silicate material to produce the potassicchlorohastingsite as cooling proceeded the liquid phase eventually became more oxidized and reacted with the pyrrhotite sulfide oxidation resulted in so4 2 formation and concomitant acid production setting the stage for jarosite formation once the fluid cooled beyond the upper thermal stability of jarosite 200 c as the fluid cooled below 200 c jarosite continued to precipitate with hematite and or goethite until equilibrium was established or reactions became kinetically unfavorable this work suggests an additional jarosite hematite formation pathway on mars one that may be important wherever magmatic hydrothermal fluids come into contact with primary sulfide grains at the martian surface or subsurface moreover hydrothermal fluids rich in chlorine sulfur and iron are important for ore forming processes on earth and their indirect identification on mars may have important implications for ore formation on mars

the genesis of coal from the viewpoint of coal petrology abstract the genesis of the microscopic constituents of coal macerals and of maceral associations microlithotypes representing various coal facies is discussed in the light of recent advances that have been made in the study of coals and modern peats peat microscopy especially promoted the understanding of humification and biological gelification both of which are decisive for the genesis of huminites vitrinites in brown coals and hard coals respectively microbial activity during peatification has been documented by chemists microbiologists and petrologists and recently by electron microscopical observations in coals this activity leads to the incorporation of lipid substances into the humic matter and later influences the chemical physical and technological properties of vitrinites geochemical gelification transforms the huminites of brown coals into the vitrinites of bituminous coals and is probably caused by the onset of bitumen generation in coal in this process the hydrogel brown coal is transformed to the bitumogel bituminous coal coal as a source rock for oil has become an important research subject for coal petrologists and oil exploration the formation of more or less liquid bitumen and its later cracking to gaseous hydrocarbons leads to the coalification jumps of the macerals especially liptinites and vitrinites and to the generation of secondary macerals like exsudatinite bitumen and micrinite dead carbon bituminization in coal has been revealed by the use of fluorescence microscopy which also found the presence of new liptinite macerals bituminite fluorinite and exsudatinite and suggests a higher proportion of algal material in coals than was thought earlier the genesis of various types of inertinite macerals will probably become an increasingly important subject of research especially with regard to rank inertinites that seem to attain their high inertinitic reflectance initially during coalification besides the origin of macerals the origin of various coal facies in terms of maceral associations is considered in relation to the palaeogeographic depositional milieu the peat forming vegetation palaeoclimate water and nutrient supply acidity marine and calcareous influence and fire with examples from euramerican carboniferous coals gondwana coals and tertiary brown coals vegetation water and oxygen supply eh conditions are most important for the generation of coal facies vegetation has been reconstructed with the help of palaeobotany including palynology cuticular analysis and wood anatomy in brown coals and with the study of petrified permineralized peats preserved in coal balls the microscopical investigations of botanically recognizable plant remains isolated from coals or accompanying rocks has been especially informative however the results of palynological and cuticular analyses should be evaluated with caution considering the varying resistance of palynomorphs and cuticles and in the case of palynomorphs their possible extrapaludal origin microscopical studies of modern peats that were derived from different types of vegetation growing in different hydrological environments have been very helpful in interpreting coal facies especially in brown coals the much disputed origin of brown coal lithotypes is considered in detail for hard coals there seems to be agreement that coal layers rich in vitrites and liptinite poor clarite were deposited in wet forest swamps that microlayered liptinite rich clarites are sub aquatic humic muds and that inertinite rich durites represent oxidized peats the origin of liptinite rich durites is controversial either subaquatic muds or oxidized peats the latter perhaps from raised bogs a recent trend in the literature is the assumption that many if not all mineable coal seams have been deposited in raised bogs under ombrogenous oligotrophic conditions although raised bogs with a dense arborescent vegetation are known from borneo it seems not probable that most seams which were deposited in foredeeps or steadily sinking graben zones are of ombrogenous origin although a succession from relatively wet and eutrophic to relatively dry and oligotrophic conditions may be true for occasional seams but as in modern peats striking changes of coal facies are commonly caused by hydrological events e g inundations as a consequences of crevasses or of fires that burned the peat the origin of the inertinite rich gondwana coals is discussed in relation to their specific climatic conditions and a comparison with sub arctic peats is recommended coals influenced by marine and calcareous conditions are characterized by high contents of sulfur and pyrite as well as by hydrogen rich vitrinites with a relatively low reflectance and high fluorescence all due to a strong bacterial activity in peats of low acidity proposals for further research are made in the conclusions

rio tinto sedimentary mineral assemblages a terrestrial perspective that suggests some formation pathways of phyllosilicates on mars abstract the presence of extensive phyllosilicate deposits from the early noachian of mars are often interpreted as having formed from neutral to subalkaline solutions in this paper we examine the rio tinto fluvial basin an early mars analog that hosts clay production and sedimentation along the entire course of the river at rio tinto phyllosilicate minerals including clays and micas are sourced by volcanosedimentary bedrock of rhyolitic and andesitic composition affected by carboniferous hydrothermal alteration pleistocene to modern acidic weathering of those materials chemically altered the volcanic and sedimentary materials to k na clay montmorillonite smectites kaolinite assemblages in paleosoils and fractures while physical weathering degrades phyllosilicates more resistant to acidic attack during the wet season phyllosilicates are eroded transported and deposited from both acidic headwaters and neutral tributaries during the dry season sulfates and nanophase oxyhydroxides co precipitate late summer storms that cause fast flooding events mix illite quartz feldspars iron oxides and other minerals in fluvial deposits where these minerals are stabilized and aggrade until the following wet season as a result chemical precipitates primary phyllosilicates and secondary clays form mineral admixtures that explain the compositional diversity of the fluvial deposits these deposits reveal the persistence of smectites whose occurrence is explained given that the reaction kinetics under acidic conditions of degradation is lowered by seasonal discharges of the river the longevity of phyllosilicate minerals within fluvial deposits depends on climatic and geochemical conditions and processes which are in turn are correlated to temperature persistence of water hydrological cycling hydrogeochemistry and composition of the source materials in the basement these parameters are universal and have to be characterized in order to understand the distribution of mineral composition on any planetary surface including mars

geochemistry of trace elements in coals from the zhuji mine huainan coalfield anhui china the abundances of nine major elements and thirty eight trace elements in 520 samples of low sulfur coals from the zhuji mine huainan coalfield anhui china were determined samples were mainly collected from 10 minable coal seams of 29 boreholes during exploration the b content in coals shows that the influence of brackish water decreased toward the top of coal seams marine transgression and regression occurred frequently in the lower shihezi formation a wide range of elemental abundances is found weighted means of na k fe p be b co ni cr se sb ba and bi abundances in zhuji coals are higher and the remainder elements are either lower or equal to the average values of elements in coals of northern china compared to the chinese coals the zhuji coals are higher in na k be b cr co se sn sb and bi but lower in ti p li v and zn the zhuji coals are lower only in s p v and zn than average u s and world coals potassium mg ca mn sr as se sb and light rare earth elements lree had a tendency to be enriched in thicker coal seams whereas fe ti p v co ni y mo pb and heavy rare earth elements hree were inclined to concentrate in thinner coal seams the enrichment of some elements in the shanxi or upper shihezi formations is related to their depositional environments the elements are classified into three groups based on their stratigraphic distributions from coal seams 3 to 11 2 and the characteristics of each group are discussed lateral distributions of selected elements are also investigated the correlation coefficients of elemental abundances with ash content show that the elements may be classified into four groups related to modes of occurrence of these elements

distribution of major minor and trace elements in hat creek deposit no 2 british columbia canada abstract the major minor and trace element contents of coals from hat creek no 2 deposit british columbia are determined using inaa and inductively coupled plasma emission spectrometry boron only al cr fe mn and na were found to be inorganically bound in the coal while as b and s are associated with the organic fraction of the coal the rare earth element concentrations in the coal are variable however the lree hree ratio decreases from base to the top of the deposits many elements show little variation in concentration with depth however the gradual increase of as and s with depth appears to be rank related and indicative of progressive decrease in porosity with increasing rank concentrations of b and cr are sensitive to the environment of coal deposition with coal deposited in a freshwater environment hat creek no 2 deposit having low b and high cr compared with more brackish coals

petrology and chemistry of permian coals from the parana basin 1 santa terezinha leao butia and candiota coalfields rio grande do sul brazil the current paper presents results on petrological and geochemical coal seam characterization in permian coal bearing strata from the parana basin southern brazil sequence stratigraphic analysis shows that peat accumulation in permian time was closely linked to transgressive regressive cycles with peat accumulation occurring in a predominantly back barrier lagoonal setting coal petrographic analysis indicates subbituminous coals at candiota and leao butia and high volatile bituminous coals at santa terezinha where locally the coal seams are thermally altered by volcanic intrusions petrographic composition is highly variable with seams at candiota and santa terezinha frequently enriched in inertinite chemical analyses indicate that all coals are mineral matter rich mean 49 09 wt with sio2 and al2o3 dominating as determined by icp aes quartz is also the predominant mineral detected by x ray diffraction where it is associated with feldspar kaolinite and hematite and iron rich carbonates the results from scanning electron microscopy are broadly consistent with the bulk chemical and mineralogical analysis quartz and clays are common in all samples analyzed other minerals observed were amongst others carbonates calcite siderite ankerite pyrite monazite kaolinite barite sphalerite rutile and quartz of volcanic origin the distribution of trace elements is well within the range typical for coal basins of other areas despite the fact that the parana basin coals are very high in ash yields the average concentrations for elements of environmental concern as b be cd co cr cu hg li mn mo ni pb sb se tl u v zn are similar to or less than the mean values for u s coal however considered on an equal energy basis parana basin coals will produce in combustion 5 to 10 times the amount of most elements compared to an equal weight us coal concentrations of major and trace elements such as fe b and s appear to be controlled by depositional setting with increasing values in coal seams overlain by brackish marine strata hierarchical cluster analysis identified three groups of major minerals and seven groups of trace elements based on similarity levels on a regional scale the coalfields can be separated by the differences in rank candiota and leao butia versus santa terezinha and by applying discriminant analysis based on 4 trace elements li as sr sb highest rb and sr values occur at candiota and are linked to syngenetic volcanism of the area whereas high y and sr values at santa terezinha can be related to the frequent diabase intrusions in that area

illite and hydrocarbon exploration illite is a general term for the dioctahedral mica like clay mineral common in sedimentary rocks especially shales illite is of interest to the petroleum industry because it can provide a k ar isotope date that constrains the timing of basin heating events it is critical to establish that hydrocarbon formation and migration occurred after the formation of the trap anticline etc that is to hold the oil illite also may precipitate in the pores of sandstone reservoirs impeding fluid flow illite in shales is a mixture of detrital mica and its weathering products with diagenetic illite formed by reaction with pore fluids during burial k ar ages are apparent ages of mixtures of detrital and diagenetic end members and what we need are the ages of the end members themselves this paper describes a methodology based on mineralogy and crystallography for interpreting the k ar ages from illites in sedimentary rocks and for estimating the ages of the end members

stratigraphic and micropetrographic occurrences of pyrite in sediments at the confluence of carbonate and peat forming depositional systems southern florida u s a abstract this study was undertaken to investigate peat carbonate relationships in a modern coal forming setting with initial research on pyrite and sulfur contents relative to stratigraphic and petrographic conditions over 40 closely spaced cores were taken from transects from florida bay inland through mangrove swamps and freshwater everglades core stratigraphy confirms on overall transgressive sequence but new evidence supports a small regression within the overall transgression on average both total s and pyrite are lowest at inland sites highest near the coastline and intermediate in florida bay sediments total s is higher in marine than freshwater peats but freshwater peats overlain by marine peats are enriched in s in cores that start with peat at the top pyrite is generally absent or very low in the top 20 cm higher percentages of pyrite occur in carbonate rather than peat facies pyrite exists in three forms framboidal aggregates minute crystals and large solitary crystals most of the pyrite occurs as minute crystals m and framboidal aggregates the occurrence of large crystals 2 m is less common and generally restricted to the cavities of larger cells or cavities within other organics e g formminifera pollen grains fungal sclerotia a general relationship seem to exist in certain cases between the occurrence of spherical organic cell fillings and the occurrence of the framboidal form of pyrite

formation of jarosite bearing deposits through aqueous oxidation of pyrite at meridiani planum mars 1 the discovery of sulfate rich layered deposits with hematite spherules at the landing site of the opportunity rover is consistent with mineral deposition in an aqueous environment we evaluate conditions responsible for the formation of a jarosite goethite gypsum assemblage with speciation calculations the results show that the assemblage could have precipitated from acidic solutions formed through near surface aqueous oxidation of pyrite our hypothesis is that regional heating in the meridiani planum caused a release of sulfide rich hydrothermal waters leading to formation of pyrite rich regional deposits in a depression aqueous oxidation of these deposits by atmospheric o2 created an acidic environment that allowed formation of sulfates and goethite partial neutralization of the solution caused further goethite precipitation and conversion of jarosite to goethite leading to formation of goethite concretions subsequent dehydration of goethite to coarse grained hematite would also have been facilitated by regional heating

characterization and quantification of inorganic constituents of tropical peats and organic rich deposits from tasek bera peninsular malaysia implications for coals abstract since the carboniferous tropical latitudes have been the site of formation of many economic coal deposits most of which have a restricted range of mineralogical composition as a result of their depositional environment climatic conditions and diagenesis mineralogical and microscopic investigations of tropical peats from tasek bera peninsular malaysia were performed in order to better understand some of these factors controlling the nature distribution and association of inorganic matter in peat forming environments distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system because the inorganic composition of peat deposits is determined by plant communities height of water table and climate the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions tasek bera is a peat accumulating basin in humid tropical malaysia with organic deposits of low to high ash yield and thus representative of many ancient peat forming environments clay minerals dominate the mineralogical composition of the peat and organic rich sediments while quartz and clays dominate the underlying siliciclastic deposits kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite particle size analyses indicate that 50 of the inorganic detrital fraction is 75 of the ash constituents as a consequence the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals the ash content of the often inundated peat consists on average of 10 opaline silica from diatoms and sponge spicules while the ash of the top deposits may have up to 50 biogenic silica hence al and si hydroxides and the opaline silica from diatoms and sponges represent a large repository of al and si which may form the basis of mineral transformation neoformation and alteration processes during coalification of the peat deposits as a result most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays such as kaolinite detrital kaolinite resilisified kaolinite or desilisified gibbsite or illite and various amounts of detrital and authigenetic quartz

distribution of sulfur in coals of the teruel mining district spain abstract the total pyritic sulfate and organic sulfur contents of the albian coals of the teruel coal mining district were determined the results have enabled us to describe the distributive characteristics of the sulfur in the study area in terms of coal seam stratigraphic series and sedimentary basin the accepted influences of the marine depositional environment and the diagenetic evolution of the coal seams on the sulfur content are reflected in this distribution moreover it is demonstrated that this distribution is modified by the massive leaching of sulfates from continental sourcelands towards the sedimentary basin owing to this the coal seams from proximal series without marine influence have a higher sulfur content than the coal seams from the series with a clear marine influence which is contrary to what has normally been reported

dating incipient metamorphism using 40 ar 39 ar geochronology and xrd modeling a case study from the swiss alps six samples of a single carbonate rich unit of the swiss prealpes progressively metamorphosed from diagenesis to deep anchizone yield 40ar 39ar spectra with variably developed staircase patterns consistent with mixtures of detrital mica and neocrystallized mixed layer illite smectite the lowest temperature heating steps for different size fractions 2 6 m and 6 20 m converge to 40 ma providing an imprecise maximum age of regional metamorphism a method is described for distinguishing and quantifying the amount of pre existing detrital mica versus neoformed illite layer in the illite smectite formed during tertiary alpine metamorphism by comparison of x ray diffraction patterns with newmod simulations in the least metamorphosed samples the illite smectite contains 65 neoformed illite and this illite accounts for approximately 17 of all dioctahedral phyllosilicate minerals in the rock e g detrital mica and illite smectite in contrast the illite smectite from the more strongly metamorphosed samples contains 97 neoformed illite which accounts for 70 to 90 of all dioctahedral phyllosilicate minerals phyllosilicate morphologies viewed by scanning electron microscopy are consistent with these estimates a process of dissolution reprecipitation is inferred as a mechanism for the growth of the neoformed phyllosilicates a plot of neoformed illite content versus 40ar 39ar total fusion age yields a near linear curve with an extrapolated age of 27 ma for 100 neoformed dioctahedral phyllosilicates this age is interpreted as the time of incipient metamorphism and is consistent with independent biostratigraphic constraints model 40ar 39ar age spectra constructed with the xrd simulation results correspond well to the experimental data and illustrate the changes in degassing properties of progressively metamorphosed mixtures of detrital mica and neoformed illite

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

surface analysis of pyrite in the no 9 coal seam wuda coalfield inner mongolia china using high resolution time of flight secondary ion mass spectrometry abstract the chemical composition of pyrite in coal can be used to investigate its geological and mineralogical origin in this paper high resolution time of flight secondary ion mass spectrometry tof sims was used to study the chemical composition of various pyrite forms in the no 9 coal seam st d 3 46 from the wuda coalfield inner mongolia northern china these include bacteriogenic framboidal massive cell filling fracture filling and nodular pyrites in addition to fe 54fe 56fe 57fe other fragment ions were detected in bacteriogenic pyrites such as 27al si 28si 29si 30si 40ca cu 63cu 65cu zn 64zn 66zn 67zn 68zn ni 58ni 60ni 62ni and c3h7 tof sims images show bacteriogenic pyrites are relatively rich in cu zn and ni suggesting that bacteria probably play an important role in the enrichment of cu zn and ni during their formation intense positive secondary ion fragments from framboidal aggregates such as 27al 28si 29si alo ch2 c3h3 c3h5 and c4h7 indicate that formation of the framboidal aggregates may have occurred together with clay mineral and organic matter which probably serve as the binding substance the intense ions of 28si and 27al from massive pyrites also suggest that their pores incorporated clay minerals during crystallization together with the lowest 28si 23na value the intense organic positive secondary ion peaks from cell filling pyrites such as c3h3 c3h5 c3h7 and c4h7 indicate that pyrite formation may have accompanied dissolution or disintegration of the cell the intense p peak was observed only in the fracture filling pyrite and the highest 28si 23na value of fracture filling pyrite reflects its epigenetic origin together with xrd and rees data the stronger 40ca in nodular pyrite than other pyrite forms shows seawater influence during its formation

opaline silica in young deposits on mars high spatial and spectral resolution reflectance data acquired by the mars reconnaissance orbiter compact reconnaissance imaging spectrometer for mars crism instrument reveal the presence of h 2o and sioh bearing phases on the martian surface the spectra are most consistent with opaline silica and glass altered to various degrees confirming predictions based on geochernicall experiments and models that amorphous silica should be a common weathering product of the basaltic martian crust these materials are associated with hydrated fe sulfates including h 3o bearing jarosite and are found in finely stratified deposits exposed on the floor of and on the plains surrounding the valles marineris canyon system stratigraphic relationships place the formation age of these deposits in the late hesperian or possibly the amazonian implying that aqueous alteration continued to be an important and regionally extensive process on mars during that time

quality palynology and palaeoenvironmental interpretation of the ilgin lignite turkey the ilgin lignite field can be subdivided into the haramikoy and kurugol areas which are separated by an area of basement and a fault the lignite bearing sequence consists mainly of fluvial and lacustrine neogene deposits the ilgin lignite averaging 8 m up to 25 m thick is blackish brown and dark brown in colour the lignite contains abundant brown wood plant remains and white gastropod shells samples have an average of 38 9 moisture on an as received basis and a mean of 3 9 total sulphur on an air dried basis geochemical analysis using an icp ms was undertaken thirteen lignite core samples from three boreholes drilled in the kurugol area were ashed at 750 c the average trace element contents of the lignite show a higher concentration of u average 43 ppm when compared to the range for most coals in the world while the others ti p sc be mn co cu zn ga as rb sr zr nb mo cs ba y ta w tl pb bi th la ce pr nd sm eu gd tb dy ho er yb lu agree with the global ranges the ilgin lignite is identified as of middle miocene middle serravallian age and occurs within lacustrine sediments deposited under subtropical climatic conditions

the age palaeoclimate palaeovegetation coal seam architecture mire types paleodepositional environments and thermal maturity of syn collision paralic coal from mukah sarawak malaysia abstract the mukah coal accumulated in the balingian formation where the time stratigraphic position is poorly defined by fauna though a probable late miocene age has always been assigned to this formation samples collected in the present study that yielded an abundance of casuarina pollen associated with occurrences of dacrydium stenochlaena palustris florschuetzia levipoli and also stenochlaena areolaris spores compare closely to zone pr9 of the palynological zonation of the malay basin and can be tied to depositional sequences of malay basin seismic sequences i2000 i3000 indicating an early miocene age for the studied coal the early miocene age shows that the mukah coal was formed during the collision between luconia block dangerous grounds with the borneo that lasted from late eocene to late early miocene the rapid increase of deposition base level caused by the collision is clearly reflected by the architecture of the mukah coal seams that were generally thin and also by the reverse order of the paleo peat bodies the studied coal samples contained large amounts of detrohuminite without the enrichment of liptinite group macerals usually explained by the dominance of herbaceous plants in the paleomires however the pollen assemblages recovered in the present study provide no support for a herbaceous swamp instead the peats were likely formed mainly from forest vegetation based on the recovery of dominant arboreal pollen assemblages in the present study palynomorph assemblages recovered in the present study with abundance of casuarina pollen associated with common occurrences of dacrydium strongly suggest kerangas vegetation and kerapah type peat swamps indicating a very wet climate the occurrence of rattan and pandanus pollens shows that the kerapah type peat swamps were locally bordered by rattan and pandanus swamps this shows that the prevailing use of coal petrography to discern the type of vegetation that was present in the peat forming mires may lead to wrong conclusions therefore a multi disciplinary approach must be applied for a more accurate and reliable spatial interpretation of the type of vegetation that was present in the peat forming mires consistent with the low sulphur content evidence from the palynomorph assemblages recovered from the coal seams shows that the coal forming peat was deposited in freshwater mires with little or no marine influence despite the fact that the accumulation of the mukah coal forming peat took place within a coastal plain setting moreover the fauna present in the host rock formation also suggested a brackish water environment of deposition

study of current dynamics of soils from a podzol oxisol sequence in tahiti french polynesia using the test mineral technique abstract the current soil dynamics of a podzol oxisol climosequence located in tahiti on basaltic and pyroclastic parent rocks has been investigated using the test mineral technique the test mineral a vermiculite with a high exchange capacity 161 meq 100 g was placed in recoverable bags in the a and b horizons of three members of the sequence for periods of 1 to 3 5 years changes in the chemistry and mineralogy enabling complexing acid environments to be distinguished from non complexing were determined following the in situ reaction with natural soil leachates a set of leachates from the same horizons were collected and chemically analysed at the end of 3 5 years the results indicate that the current acid environment is only weakly complexing this suggests that the podzolisation processes which led to the development of a unique a2 horizon containing gibbsite anatase and rutile and a placic horizon in the upper podzol member of the sequence is no longer operating

a mineralogical archive of the biogeochemical sulfur cycle preserved in the subsurface of the rio tinto system the search for extinct and extant life on mars is based on the study of biosignatures that could be preserved under mars like extreme conditions that are replicated in different terrestrial analog

large scale fluid flow in the middle devonian presqu ile barrier western canada sedimentary basin saddle dolomite cements are regionally extensive in the middle devonian presqu9ile or keg river barrier and are spatially associated with mississippi valley type mineralization at pine point northwest territories from northeastern british columbia to pine point over a lateral distance of 400 km these dolomite cements show general trends of decreasing 87 sr 86 sr ratios 0 7106 to 0 7081 and homogenization temperatures 178 to 92 c with some increase in 18 o values 16 to 7 pdb these regional trends suggest that hotter and more radiogenic basinal fluids moved eastward updip along the presqu9ile barrier and mixed with cooler ambient formation waters these movements of basinal fluids were probably related to tectonic thrusting and compression sedimentary loading and tectonic uplift on the western margin of the western canada sedimentary basin which began to form during late jurassic to early cretaceous time and climaxed during the late cretaceous to paleocene the middle devonian presqu9ile barrier appears to have acted as a deeply buried regional conduit system that played an important role in focusing and channeling these basinal fluids these regional fluid flows appear to have been responsible for extensive burial dolomitization secondary migration of hydrocarbons and local mississippi valley type mineralization in the western canada sedimentary basin

development of potential acid sulfate paleosols in paleocene floodplains bighorn basin wyoming usa abstract floodplain paleosols in the paleocene fort union formation in the bighorn basin are distinguished by a dark claystone interval with yellow jarosite mottles relatively high total organic carbon values and woody debris and leaves along bedding planes the paleosols also have various redoximorphic features including low matrix chromas grey root mottles and local concentrations of goethite and hematite especially associated with roots and other organic matter jarosite is usually an oxidation product of pyrite which forms under waterlogged conditions when sulfate and organic matter are available the former presence of pyrite and the redoximorphic features suggest that the fort union paleosols first developed as potential acid sulfate soils brinkman and pons 1973 the dark claystones with jarosite are interpreted as permanently reduced or gr horizons the gr horizon is overlain by mudstone that is lighter colored and lacks jarosite this represents an ancient bg horizon or a bg sequence the jarosite indicates that the paleosols underwent a subsequent episode of oxidation and acidification those processes require that the soils be drained which probably did not occur during paleocene time and may be a recent event rather the soils were probably buried as the fort union formation continued to aggrade and the waterlogged soils were pushed even farther below the groundwater table only with late cenozoic excavation of strata in the basin and exposure of the fort union deposits did jarosite precipitate pedogenic and paleobotanical features suggest that the soils formed in floodplain swamps dominated by coniferous trees the high organic content and clay rich nature of the gr horizons suggest that the floodplain swamps were not close to the active channel the bipartite nature to the profiles bg horizon or a bg sequence above a gr horizon probably resulted from two different kinds of floodplain deposition grain size trends indicate that the gr horizons formed on sediment deposited by overbank flooding the impermeable fine grained sediment and its low topographic position led to waterlogging the overlying a bg or bg horizons formed on coarser sediment that was probably deposited during channel avulsion the greater permeability and higher topographic position of this sediment caused it to be better drained than the gr horizon the paleosols are unusual because they formed in a freshwater setting whereas modern potential acid sulfate or acid sulfate soils form in coastal areas where sulfate is readily available the source of the sulfate may have been cretaceous marine shales exposed along the flanks of mountains rising around the bighorn basin during paleocene time other upper cretaceous and paleocene formations in the rocky mountain area contain similar rocks suggesting that sulfidic soils were relatively common in the mid continent at this time most of these other examples probably reflect deposition associated with the retreating western interior seaway and humid climates

orbital evidence for clay and acidic sulfate assemblages on mars based on mineralogical analogs from rio tinto spain outcrops of hydrated minerals are widespread across the surface of mars with clay minerals and sulfates being commonly identified phases orbitally based reflectance spectra are often used to classify these hydrated components in terms of a single mineralogy although most surfaces likely contain multiple minerals that have the potential to record local geochemical conditions and processes reflectance spectra for previously identified deposits in ius and melas chasma within the valles marineris mars exhibit an enigmatic feature with two distinct absorptions between 2 2 and 2 3 m this spectral doublet feature is proposed to result from a mixture of hydrated minerals although the identity of the minerals has remained ambiguous here we demonstrate that similar spectral doublet features are observed in airborne field and laboratory reflectance spectra of rock and sediment samples from rio tinto spain combined visible near infrared reflectance spectra and x ray diffraction measurements of these samples reveal that the doublet feature arises from a mixture of al phyllosilicate illite or muscovite and jarosite analyses of orbital data from the compact reconnaissance imaging spectrometer for mars crism shows that the martian spectral equivalents are also consistent with mixtures of al phyllosilicates and jarosite where the al phyllosilicate may also include kaolinite and or halloysite a case study for a region within ius chasma demonstrates that the relative proportions of the al phyllosilicate s and jarosite vary within one stratigraphic unit as well as between stratigraphic units the former observation suggests that the jarosite may be a diagenetic authigenic product and thus indicative of local ph and redox conditions whereas the latter observation may be consistent with variations in sediment flux and or fluid chemistry during sediment deposition

sulfur variability and petrology of the lower block coal member pennsylvanian in southwest indiana abstract the lower block coal member pennsylvanian atokan westphalian c is an economic low to medium sulfur low ash coal resource in the illinois basin sulfur content is generally low averaging 1 0 in the study area but varies over short distances higher sulfur areas occur as isolated pods and epigenetic pyrite increases significantly in the upper third of the selected columns in higher sulfur areas sulfur variations cannot be predicted by typical geologic characteristics such as roof lithology seam thickness or seam elevation petrographic analysis shows that pyrite is generally associated with brighter microlithotypes except in higher sulfur areas where infilling pyrite forms are associated with inertite higher sulfur areas reflect the water chemistry of the paleomire during and shortly after peat accumulation locally abundant pyrofusinite provided additional pore space for pyrite precipitation

fossilization potential of iron bearing minerals in acidic environments of rio tinto spain implications for mars exploration abstract acidic waters of the rio tinto southwestern spain evaporate seasonally precipitating a variety of iron sulfide and oxide minerals schwertmannite and nanophase goethite form thin laminae on biological and detrital grain surfaces replicating among other things the morphologies of insect cuticle plant tissues fungi algae and bacteria intergrain cements also incorporate bacterial cells and filaments other sulfate minerals precipitated in rio tinto environments are transient and contribute little to short term preservation because the rio tinto has been cutting its current valley for several million years terrace deposits provide a window on longer term fossil preservation early and later diagenesis are recorded in terrace deposits formed about one thousand and two million years ago respectively the sedimentary structures and mineralogies of these deposits suggest that they formed under physical and chemical conditions comparable to those of modern rio tinto sediments the terrace deposits show quantitative loss of sulfate minerals increasing crystallinity of goethite and in the older terrace replacement of goethite by hematite fossils formed originally by schwertmannite and nanophase goethite replication persist through diagenesis preserving a long term record of local biological diversity fossil preservation by iron oxides in the acidic environment of rio tinto suggests that if life was present when sedimentary rocks formed at meridiani planum mars precipitated minerals could record their presence

the geology botany and chemistry of selected peat forming environments from temperate and tropical latitudes abstract peat has been studied in several geologic settings 1 glaciated terrain in cold temperate maine and minnesota u s a 2 an island in the atlantic ocean off the coast of maine where sea level is rising 3 the warm temperate u s atlantic and gulf coastal plains where sea level has changed often and 4 the tropical coast of sarawak malaysia and the tropical delta of the batang hari river sumatra indonesia most of these deposits are domed ombrotrophic or partly ombrotrophic bogs in which peat accumulation continued above the surface of the surrounding soil however the bogs of the u s atlantic and gulf coastal plains are comparatively not as domed and many have almost level surfaces in some bogs aquatic or semi aquatic plant materials accumulated replaced water in the depressions and formed a surface on which marsh or swamp vegetation could subsequently live die and accumulate in others the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps as the peat dome formed plants growing on it changed from luxuriant ones near the base of the dome where nutrients were brought into the bog by surface and ground water to stunted ones at the top of the dome where the raised bogs are fed by nutrient poor precipitation the physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development through the grassy marsh stage through the forested swamp stage and finally through the heath dome stage can be measured in terms of acidity and ash volatile matter carbon hydrogen nitrogen sulfur and oxygen contents as well as in the kind and distribution of trace elements the organic and inorganic contents of the deposits relate to geomorphology and geomorphology relates to their settings as models of coal formation some domed peat deposits may help in solving problems of distribution and character of ancient coal beds but clearly not all peat deposits are precursors of coal most holocene peat deposits are subject to destruction by erosion fire and decomposition through microbial and chemical oxidation before burial the best environments for coal precursors have biomass accumulation a continuously rising water table within the mass and minimum influx of clay and silt until preservation by burial the most suitable settings for future economic coal deposits are domed bogs that accumulate thick widespread peat having low ash and low sulfur contents the ombrotrophic peat deposits of tropical sarawak and sumatra are thick and extensive contain low ash and low sulfur peat and have high heating values they are considered to be the best tropical coal analogs because of their extent and chances of preservation the base of the peat is below adjacent river levels and chemical and structural conditions are favorable for accumulation

sulphur in pennsylvania coals of atlantic canada geologic and isotopic evidence for a bedrock evaporite source abstract higher sulphur contents in coals are commonly explained by the proximity of the original peat to marine waters during deposition as the sulphate ions in seawater provide an abundant source of sulphur however pennsylvanian coals of the maritimes basin which commonly contain 5 8 sulphur are associated with a predominantly freshwater biota and alluvial sedimentary features and evidence for marine beds is scare several workers have suggested that the sulphur was derived from dissolution of thick sulphate evaporites in the underlying mississippian windsor group rather than from pennsylvanian seawater we set out to test this hypothesis using a biogeochemical model derived from studies of sulphur isotopes in modern peat swamps during the bacterial decomposition of plant material the h 2 s generated from groundwater sulphate is fixed as metal sulphides which are enriched in the lighter 32 s isotope by 15 or more sulphides formed chemically during burial will be much less fractionated isotope ratios of sulphur bearing products can thus be used to trace the original source of the sulphur by comparison with a source of known isotopic composition eight evaporite samples from the upper windsor group in the sydney basin have a mean 34 s value of 15 sixteen pyrite samples from five coal seams in the overlying morien group range from 14 8 to 5 34 s the pyrite values follow the pattern predicted for derivation from windsor sulphates disseminated pyrite generally contains more highly fractionated sulphur than nodular pyrite suggesting that much of the former was generated by bacterial action whereas the latter was produced during later burial isotopic ratios for soluble sulphate in the coal correspond closely to those for the associated pyrite because mississippian and pennsylvanian seawaters showed a similar range of 34 s values the test does not preclude a pennsylvanian marine source of sulphate both geological and isotopic data however are consistent with a windsor evaporite source

occurrence and distribution of sulfur in peat forming environments of southern florida abstract cores and surface samples of peats from the everglades mangrove region of southern florida were analyzed for total sulfur and pyritic sulfur these values were compared with the petrographic botanical components of the peats as determined from point counts of oriented microtome sections pyrite occurs as individual euhedral crystals loosely packed framboids and lenses or crusts of minute crystals framboids and minute crystals are often associated with organic matter and sometimes with bacteria and fungi pyrite tends to selectively occur in void spaces in or between peat tissues in samples containing very small amounts of pyrite framboidal pyrite is the prevalent form marine to brackish peats contain the highest pyrite and total sulfur contents with brackish peats generally containing more pyrite than marine peats pyrite tends to be lower in all peats within 30 cm of the surface whether marine or brackish burial of freshwater peats beneath marine or brackish peats tends to increase the total sulfur and pyritic sulfur in the underlying peats burial beneath brackish water clay rich deposits such as splays tends to increase total sulfur and pyritic sulfur in the underlying deposits more than burial beneath less clay rich deposits

produced fluids and shallow groundwater in coalbed methane cbm producing regions of alberta canada trace element and rare earth element geochemistry abstract the production of coalbed methane cbm represents a vital new source of natural gas supply in western canada there are however concerns over potential negative environmental impacts on groundwater resources caused by potential contamination with fluids and gases from coal bearing strata this paper provides a brief description of the geochemistry and a detailed discussion of trace element and rare earth element ree concentrations of the produced fluids from two major coal deposits in western canada the mannville formation and the horseshoe canyon belly river group hscn brg and shallow groundwater sgw in this region it evaluates how the depositional environment redox conditions and water rock interactions influence the trace element and rare earth element distributions in the produced fluids and sgw of the study area produced waters from the mannville formation are a saline na cl type and a high boron content is indicative of a brackish marine depositional environment in contrast the hscn brg produced fluids are a na hco3 water type and have lower total dissolved solids tds and lower boron concentrations shallow groundwater has a na hco3 to na hco3 so4 water type with often high concentrations of sulphate and low tds some groundwater samples many hscn brg and all mannville fluids had low sulphate concentrations often with elevated 34s values indicating that bacterial sulphate reduction had occurred making the redox environment suitable for methanogenesis dissolved gas from the mannville formation had a notable thermogenic component whereas dissolved gas from the hscn brg and free gas in shallow groundwater contained methane predominantly or exclusively of biogenic origin mannville produced waters are up to 70 times more concentrated in trace elements compared to the hscn brg waters and up to 300 times more concentrated than shallow groundwater in the mannville fluids trace elements such as as se and pb occurred in concentrations often exceeding drinking water guidelines 5 g l 10 g l and 10 g l respectively whereas most samples in the hscn brg contained only se above drinking water guidelines and a few samples contained as and pb slightly above the maximum allowable concentrations for drinking water therefore the potential risk of trace metal contamination of shallow groundwater with hscn brg swabbing fluids is low because of their comparatively low trace metal content rare earth elements in the mannville produced fluids indicate interaction with silicate dominated host rocks in contrast the rees of the hscn brg produced fluids show interaction with carbonate rich material the shallow groundwater shows a similar pattern to the hscn brg suggesting that rees are not a suitable parameter to monitor potential contamination of shallow groundwater with cbm fluids from the hscn brg however several other geochemical and isotopic parameters are sufficiently distinct between shallow groundwater hscn brg and mannville fluids so that cross contamination with produced fluids or gases should be identifiable with a suitable geochemical monitoring program

relationship between petrographic and chemical properties and coal seam geometry hance seam breathitt formation southeastern kentucky the upper hance coal seam in southeastern kentucy was used as a template to examine the spatial distribution of ash yield sulfur content and petrographic constituents relative to the geometry of the deposit geometric characteristics include thinning and splitting of the two main benches leaders and riders analytical data showed the thick non split portions of the coal body to be low in ash and sulfur as well as vitrinite content whereas the thinned and split margins were higher in ash sulfur and vitrinite content these relationships suggest that thick non split portions of the upper hance peat accumulated in areas isolated from detrital influx while thinner marginal peat was subject to intermittent flooding from adjacent channels marginal peat was derived from larger trees which flourished at the mire s edge in the presence of adequate nutrients whereas only stunted vegetation subsisting in the nutrient depleted center contributed to interior peat accumulation ponds formed on the sparsely vegetated mature surface of the bog s interior the petrographic and chemical character of the hance coal body is analogous to ombrogenous domed peats which characteristically contain higher concentrations of inorganics at the periphery of the deposit

geological record of an acidic environment driven by iron hydrochemistry the tinto river system 1 the existence of possible hematitic strata on the surface of mars demands a search for terrestrial analogues formed in unusual environments this will help us to recognize and interpret environmental and perhaps biological signatures preserved in mars hematites such an analogue would allow us to establish valid reference systems based on geomicrobial and biogeochemical signatures two different aspects place the tinto river inside the boundaries of a natural extreme system its high level of biological diversity and the presence of fluvial rocks formed in the same acidic conditions as in the modern system which could predate the tertiary study of both the modern system and the ancient system is necessary to understand the formation of biosignatures a chemolithotrophic community that biooxidizes the iberian pyritic belt acidifying water ph between 0 9 and 3 0 and favoring high concentrations of ferric iron in solution up to 20 g l 1 maintains this iron driven system in spite of these extreme conditions high microbial diversity was found its acidic bacteria archaea and eukarya constitute a complex community supported by algal biomass in highly stable hydrochemical conditions which are achieved through iron buffering the ph is maintained at constant low levels even at very high water dilution in these conditions iron minerals as oxyhydroxides hydroxides and sulfates are formed the modern and recent parageneses contrast with the ancient tinto river terrace mineral associations which show dehydrated and desulfated iron oxides if this dehydration process is considered these tinto river ironstones may be a key for knowing some aquatic habitats which may have hosted a part of the early mars biosphere

lake mire ecosystem transformation and its possible forcing mechanisms in volcanic landform regions a case study in the gushantun peatland of northeast china

meta gabbro weathering in the georgia piedmont usa implications for global silicate weathering rates abstract the mineral assemblages in a vertical weathering profile developed over a meta gabbro terrain were studied for their stoichiometry and relative abundances the site is located in the piedmont province in the southeast portion of the appalachians orogenic belt in a forested residual landscape and a temperate climate the soil is classified as a fine mixed thermic ultic hapludalf and defined by distinct a b and c horizons with thicknesses of 17 62 and 250 cm respectively the primary mineral assemblage consists of 44 wt andesine 40 hornblende 6 quartz 4 biotite 3 ilmenite titanomagntite rutile sphene grains and 3 epidote quantitative xrd detailed xrd clay mineralogy and thin section petrography revealed the incipient breakdown of the primary minerals to vermiculite after biotite oxidation randomly ordered mixed layer mica vermiculite smectite as grain coatings kaolin group minerals after mafic silicate dissolution goethite and hematite vermiculite after biotite expandable clay coatings and all the primary minerals with exception to quartz are dissolved away from the a horizon hydroxy interlayered vermiculite and minor amounts of gibbsite occur as tertiary phases in the a horizon using mineral stoichiometries and average abundances for the parent rock and c b and a horizon estimates of primary mineral mass loss were determined the bicarbonate to silica ratio expected from the mineral loss reactions is 6 times higher than the ratio observed in average groundwater of the georgia piedmont this suggests that although weathering of mafic terrains is important to the long term process of transferring co 2 to the oceans the present day contribution of silicate weathering in temperate climates may be more largely influenced by the weathering of felsic terrain

a model of orientation of subcrystals in saddle dolomite abstract saddle dolomite crystals are composed of subcrystals that are slightly overlapped rotated and tilted with respect to each other the subcrystal arrangement resembles a screw like pattern the c axes of subcrystals are skew lines their directions change from horizontal to steeply inclined relative to the substrate in thin section the traces of the c axes of subcrystals simulate a divergent or convergent pattern which is the cause of sweeping extinction typical of saddle dolomite

evidence for montmorillonite or its compositional equivalent in columbia hills mars 1 during its exploration of the columbia hills the mars exploration rover spirit encountered several similar samples that are distinctly different from martian meteorites and known gusev crater soils rocks and sediments occurring in a variety of contexts and locations these independence class samples are rough textured iron poor equivalent feo 4 wt have high al si ratios and often contain unexpectedly high concentrations of one or more minor or trace elements including cr ni cu sr and y apart from accessory minerals the major component common to these samples has a compositional profile of major and minor elements which is similar to the smectite montmorillonite implicating this mineral or its compositional equivalent infrared thermal emission spectra do not indicate the presence of crystalline smectite one of these samples was found spatially associated with a ferric sulfate enriched soil horizon possibly indicating a genetic relationship between these disparate types of materials compared to the nearby wishstone and watchtower class rocks major aqueous alteration involving mineral dissolution and mobilization with consequent depletions of certain elements is implied for this setting and may be undetectable by remote sensing from orbit because of the small scale of the occurrences and obscuration by mantling with soil and dust

the rio tinto basin spain mineralogy sedimentary geobiology and implications for interpretation of outcrop rocks at meridiani planum mars abstract exploration by the nasa rover opportunity has revealed sulfate and hematite rich sedimentary rocks exposed in craters and other surface features of meridiani planum mars modern holocene and plio pleistocene deposits of the rio tinto southwestern spain provide at least a partial environmental analog to meridiani planum rocks facilitating our understanding of meridiani mineral precipitation and diagenesis while informing considerations of martian astrobiology oxidation thought to be biologically mediated of pyritic ore bodies by groundwaters in the source area of the rio tinto generates headwaters enriched in sulfuric acid and ferric iron seasonal evaporation of river water drives precipitation of hydronium jarosite and schwertmannite while mg al fe3 copiapite coquimbite gypsum and other sulfate minerals precipitate nearby as efflorescences where locally variable source waters are brought to the surface by capillary action during the wet season hydrolysis of sulfate salts results in the precipitation of nanophase goethite holocene and plio pleistocene terraces show increasing goethite crystallinity and then replacement of goethite with hematite through time hematite in meridiani spherules also formed during diagenesis although whether these replaced precursor goethite or precipitated directly from groundwaters is not known the retention of jarosite and other soluble sulfate salts suggests that water limited the diagenesis of meridiani rocks diverse prokaryotic and eukaryotic microorganisms inhabit acidic and seasonally dry rio tinto environments organic matter does not persist in rio tinto sediments but biosignatures imparted to sedimentary rocks as macroscopic textures of coated microbial streamers surface blisters formed by biogenic gas and microfossils preserved as casts and molds in iron oxides help to shape strategies for astrobiological investigation of meridiani outcrops

geochemical and petrographical characteristics of a domed bog nova scotia a modern analogue for temperate coal deposits a freshwater domed bog in nova scotia canada was investigated for its petrographic mineralogical and geochemical characteristics three cores were taken from the lagg zone margin and centre to examine different stages of evolution in a fen to domed bog sequence based on this study a model was developed which shows the relationship between factors controlling peat geochemistry and petrography all of them being dependent on trophic conditions the bog may represent a modern analogue for temperate coal deposits and thus can be used to help understand spatial variability within coal beds rheotrophic conditions in the early stages of mire development result in the formation of high ash highly humified carex dominated peat while the evolution toward ombrotrophic conditions is reflected in a progressive replacement by low ash and well preserved sphagnum dominated peat the associated decrease in ph reflects a decrease of groundwater influence which is also supported by the mineralogical assemblage and petrographic data decrease in reflectance and change in maceral composition except for cl br i and se which are associated with the organic fraction variations in elemental composition can be explained in terms of mineral matter abundance i e decrease upward and with increasing distance from the margin sea spray is the most probable origin for halogen enrichment in the peat

carbonate precipitation under bulk acidic conditions as a potential biosignature for searching life on mars recent observations of carbonate minerals in ancient martian rocks have been interpreted as evidence for the former presence of circumneutral solutions optimal for carbonate precipitation sampling from surface and subsurface regions of the low ph system of rio tinto has shown unexpectedly that carbonates can form under diverse macroscopic physicochemical conditions ranging from very low to neutral ph 1 5 7 0 a multi technique approach demonstrates that carbonate minerals are closely associated with microbial activity carbonates occur in the form of micron size carbonate precipitates under bacterial biofilms mineralization of subsurface colonies and possible biogenic microstructures including globules platelets and dumbbell morphologies we propose that carbonate precipitation in the low ph environment of rio tinto is a process enabled by microbially mediated neutralization driven by the reduction of ferric iron coupled to the oxidation of biomolecules in microbially maintained circumneutral oases where the local ph at the scale of cells or cell colonies can be much different than in the macroscopic environment acidic conditions were likely predominant in vast regions of mars over the last four billion years of planetary evolution ancient martian microbial life inhabiting low ph environments could have precipitated carbonates similar to those observed at rio tinto preservation of carbonates at rio tinto over geologically significant timescales suggests that similarly formed carbonate minerals could also be preserved on mars such carbonates could soon be observed by the mars science laboratory and by future missions to the red planet

evidence of phyllosilicates in wooly patch an altered rock encountered at west spur columbia hills by the spirit rover in gusev crater mars 1 on its traverse to columbia hills the mars exploration rover spirit investigated an outcrop designated wooly patch that exhibited morphological mineralogical and geochemical characteristics at the extreme ends of ranges observed among rocks studied at west spur a westward projecting salient near the foot of the columbia hills gusev crater the major element composition and fe mineralogy as determined by the alpha particle x ray spectrometer and mossbauer spectrometer are inconsistent with any reasonable assemblage of basaltic minerals in that there is an excess of si and al the combined data are best explained by the presence of 14 17 phyllosilicate minerals phyllosilicates that account for the composition and cation ratios include members of the kaolinite serpentine chlorite and septechlorite groups the potential existence of kaolinite type al rich phyllosilicates within the wooly patch outcrop suggests a mildly acidic environment ph 4 6 in the past and an open hydrologic system with good drainage conditions in the environment where these rocks were altered

contemporaneous deposition of phyllosilicates and sulfates using australian acidic saline lake deposits to describe geochemical variability on mars 1 studies of the origin of the martian sulfate and phyllosilicate deposits have led to the hypothesis that there was a marked global scale change in the mars environment from circum neutral ph aqueous alteration in the noachian to an acidic evaporitic system in the late noachian to hesperian however terrestrial studies suggest that two different geochemical systems need not be invoked to explain such geochemical variation western australian acidic playa lakes have large ph differences separated vertically and laterally by only a few tens of meters demonstrating how highly variable chemistries can coexist over short distances in natural environments we suggest diverse and variable martian aqueous environments where the coetaneous formation of phyllosilicates and sulfates at the australian sites are analogs for regions where phyllosilicates and sulfates coexist on mars in these systems fe and alkali earth phyllosilicates represent deep facies associated with upwelling neutral to alkaline groundwater whereas aluminous phyllosilicates and sulfates represent near surface evaporitic facies formed from more acidic brines

distributions of bomb 14 c biogeochemistry and elemental concentration in hani mire peat profiles ne china implications of environmental change abstract two 50 cm long peat cores from the hani mire on the western slope of the changbai mountains northeastern china were collected for investigating physical biological and geochemical processes of the peatland in response to recent climate change the 14c dating using accelerator mass spectrometry ams on the peat cores provides a nuclear bomb carbon curve which is used for peat chronological construction the sedimentation rate sr of core s1 from a sphagnum magenllanicum hummock in the hani mire was about 0 98 cm y and deposited from 1957 2008 ce whereas the sr of core s2 from s palustre hummock 1 km apart from s1 was 1 59 cm y and accumulated during 1976 2008 the discrepancy of the srs may mainly be attributed to the different inorganic material supplies from surface runoff which affected growth of sphagnum spp at different sites with lower rate corresponding to higher inorganic contents higher ti ca and mg contents thus lower values of loss on ignition loi on the other hand the two cores had similar values and variation trends in the ph c n n and p contents and dry bulk density dbd implying that the organic source and decomposition were similar under the same climatic conditions the variations of toc c n and pb content in the peat cores matched well with the 5 y running average of local annual precipitation record with higher toc and c n but lower pb content corresponding to higher rainfall and vice versa these properties in the meso oligotrophic peat sequences can reflect climatic changes the recent rates of carbon accumulation rerca for s1 and s2 calculated from the toc dbd and sr were averaged 121 6 24 3 and 175 5 35 1 g m2 y respectively

petroleum potential of oligocene lacustrine mudstones and coals at dong ho vietnam an outcrop analogue to terrestrial source rocks in the greater song hong basin the outcrop of oligocene age at dong ho northern vietnam may constitute an immature analogue to offshore terrestrial source rocks in the greater song hong basin the outcrop includes an interval with two source rocks 1 highly oil prone carbonaceous mudstones containing kerogen types iia and iia i and with toc contents from 6 48 to 16 89 wt and hi values from 472 to 690 and 2 oilprone humic coals kerogen type iii with hi values from 200 to 242 the mudstones were deposited in oxygen deficient lakes which on occasion were subject to marine influence and the coals accumulated in freshwater peat forming mires the coals have broad activation energy ea distributions while the mudstones have ea distributions characterised by a pronounced principal ea during artificial maturation about 16 17 of the organic carbon in the coals and 45 50 of the organic carbon in the mudstones participated in petroleum formation the two source rocks primary generate oil and secondary generate gas however the mudstones realised the majority of their potential over a more narrow temperature range than the coals the excellent generative potential of the terrestrial source rocks at dong ho is encouraging for offshore exploration for reservoirs charged by cenozoic rift lake successions q 2001 elsevier science ltd all rights reserved

orbital identification of carbonate bearing rocks on mars geochemical models for mars predict carbonate formation during aqueous alteration carbonate bearing rocks had not previously been detected on mars surface but mars reconnaissance orbiter mapping reveals a regional rock layer with near infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the nili fossae region the carbonate is closely associated with both phyllosilicate bearing and olivine rich rock units and probably formed during the noachian or early hesperian era from the alteration of olivine by either hydrothermal fluids or near surface water the presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering proposed to be characteristic of hesperian mars did not destroy these carbonates and thus did not dominate all aqueous environments

some observations regarding the potential effects of doming of tropical peat deposits on the composition of coal beds abstract several important concepts relative to the origin of coal beds can be gleaned from studies of modern domed and planar peat deposits in tropical subtropical settings these are 1 laterally some portions of a single continuous peat deposit may be domed and some portions may be planar 2 domed deposits are most often found to have begun as planar deposits 3 domed formed peat facies may be overridden by planar formed peat facies due to such factors as sea level rise and or increased rate of local and basinal subsidence 4 domed peat facies tend to have less mineral matter and contain fewer inorganic splits than planar facies 5 sulfur intrusion from marine waters can be retarded by doming allowing low sulfur peats to form relatively near to the coastline 6 marine transgression can cause high sulfur marine influenced planar peat facies to override freshwater domed or planar facies resulting in enrichment of the upper parts of these underlying facies in sulfur and ash 7 dome formed peat facies tend to be thicker and more uniform in composition than planar formed facies with dome formed peat facies having the potential to produce the more uniform bright coal types clarains and vitrains and planar formed peat facies often producing duller coal types and or alternating durainic inertinite rich and vitrainic wood derived bands 8 actively developing peat domes in wet settings often exhibit no appreciable increase in inertinitic material toward their tops although the tops of either domed or planar peat deposits can be enriched in inertinitic material if the water table is lowered by either local or regional changes in hydrology or climate

the miller volcanic spark discharge experiment miller9s 1950s experiments used besides the apparatus known in textbooks one that generated a hot water mist in the spark flask simulating a water vapor rich volcanic eruption we found the original extracts of this experiment in miller9s material and reanalyzed them the volcanic apparatus produced a wider variety of amino acids than the classic one release of reduced gases in volcanic eruptions accompanied by lightning could have been common on the early earth prebotic compounds synthesized in these environments could have locally accumulated where they could have undergone further processing

geochemical compositional changes at the pliocene pleistocene transition in fluviodeltaic deposits in the tegelen reuver area southeastern netherlands o contents which can be attributed to the alpine source supplying fresh sodic plagioclase rich material instead of the local strongly weathered sediments increasing k2o al2o3 can be attributed to a similar decrease in degree of weathering however this trend is disturbed by the loss of k from clay minerals during weathering in organic rich layers local high tio2 anomalies caused by preferential sorting and concentration are found in most pliocene sections but they are absent in the upper pliocene and lower pleistocene alpine derived deposits this change is probably due to a change in the energy of the fluvial system finally pyrite s contents drop siderite fe contents rise micromorphological observations indicate that the pliocene pyrite was formed when freshwater deposits were flooded with seawater during short term events the decrease in s and the increase in siderite fe can be attributed to decreasing marine influence as a result of the marine regression at the pliocene pleistocene transition

a 3 5 ga record of water limited acidic weathering conditions on mars abstract the secondary mineral budget on earth is dominated by clay minerals al hydroxides and fe oxides which are formed under the moderate ph high water to rock ratio conditions typical of earth s near surface environment in contrast geochemical analyses of rocks and soils from landed missions to mars indicate that secondary mineralogy is dominated by mg fe ca sulfates and fe oxides this discrepancy can be explained as resulting from differences in the chemical weathering environment of earth and mars we suggest that chemical weathering processes on mars are dominated by 1 a low ph sulfuric acid rich environment in which the stoichiometric dissolution of labile mineral phases such as olivine and apatite fe ti oxides is promoted and 2 relatively low water to rock ratio such that other silicate phases with slower dissolution rates e g plagioclase pyroxene do not contribute substantially to the secondary mineral budget at the martian surface under these conditions al mobilization is limited and the formation of significant al bearing secondary phases e g clays al hydroxides al sulfates is inhibited the antiquity of rock samples analyzed in situ on mars suggest that water limited acidic weathering conditions have more than likely been the defining characteristic of the martian aqueous environment for billions of years

organic burial site on mars the nili fossae region on mars is one of the places earmarked for the search of evidence for life a combination of geomorphological and mineralogical data from the area suggest ideal conditions for the burial of organic matter

relationship between peat geochemistry and depositional environments cranberry island maine abstract the heath great cranberry island maine offers a unique locality for studying lateral and vertical relationships between radically different peat types within 1 km 2 the majority of the heath is a sphagnum moss dominated raised bog surrounding the raised bog is a swamp marsh complex containing grass sedge sphagnum moss alder tamarack and skunk cabbage swamp marsh deposited peat occurs both around the margins of the heath and under sphagnum dominated peat which was deposited within the raised bog a third peat type dominated by herbaceous aquatics is present underlying the swamp marsh dominated peat but is not present as a dominant botanical community of the heath the three peat types have major differences in petrographic characteristics ash contents and associated minerals sulfur contents range from a low of 0 19 wt dry within the raised bog to a high of 4 44 wt dry near the west end of the heath where swamp marsh peat occurring directly behind a storm beach berm has been influenced by marine waters the presence of major geochemical variations within a 1 km 2 peat deposit suggests the need for in depth characterization of potential peat resources prior to use

assessment of environmental controls on acid sulfate alteration at active volcanoes in nicaragua applications to relic hydrothermal systems on mars 1 a variety of secondary mineralogies has been detected on mars from both orbiters and landers indicating widespread aqueous alteration of the crust many of these locales exhibit sulfates which in some cases imply acidic fluids at present there are few constraints on the paleoenvironmental conditions that existed during formation of the widespread and diverse classes of secondary minerals on mars we investigated hydrothermal systems at three active acidic volcanic systems in nicaragua including cerro negro momotombo and telica the recently erupted materials are similar in composition to the martian crust and are undergoing extensive acid sulfate alteration predominately in gas dominated settings fumaroles we characterized the secondary mineralogy and local variables including temperature ph rock and gas composition and fluid rock ratio we find that these environmental parameters exhibit strong controls on the alteration mineralogy the environments studied include ph that ranged from 1 to 6 temperatures from ambient to hundreds of degrees celsius and fumaroles to hot springs the hottest and most acidic systems contained sulfur silica and minor gypsum while moderately acidic and cooler fumaroles included abundant silica gypsum and other hydrated sulfates and phyllosilicates a setting with a higher fluid rock ratio but similar temperature and acidity was dominated by phyllosilicates and to a lesser degree sulfates the characterization of aqueous alteration of basalts under a variety of environmental conditions provides a conceptual framework for interpretation of similar relic environments on mars finally while identification of phyllosilicates on mars is generally thought to require neutral to alkaline fluids we documented significant formation of these minerals in the acidic volcanic systems

distribution of forms of sulfur in peats from saline environments in the florida everglades abstract although there is published information on the mechanism of sedimentary pyrite formation resulting from bacterial reduction of sulfate little is known about the distribution of forms of sulfur including organic in peats in order to increase understanding of the geochemistry of sulfur in coals we have determined distributions of forms of sulfur in five cores of saline peat and one of brackish peat all from areas near the shark river and whitewater bay in the coastal swamps of south florida all concentrations vary widely with depth total sulfur concentrations range up to 6 of dry solids minor amounts of sulfur are present as h2s s0 so42 and acid soluble sulfide but the principal forms are usually pyritic and organic the ratio organic pyritic is highly variable but at a majority of levels in a profile is considerably greater than unity it is inferred that topochemical factors are important in determining the distribution of sulfur forms in any element of volume

geochemical data as indicators of palaeosalinity in coastal organic rich sediments abstract a geochemical study of extractable major minor and trace elements peatlands from e spain elucidated variations in salinity related to the interpretation of relative sea level change samples were taken from different peatlands from the subsiding valencia castellon quaternary basin e spain these correspond to back barrier marshes with brackish and freshwater influence containing carex juncus typha and phragmites samples from a highland sphagnum moss freshwater peat bog were also included for comparison this paper categorizes palaeosalinity indicators in this coastal peat deposits as follows b br i na s ge u this compares with low rank coal which shows the following relationship b br i s na ge u the formulation of an index for characterising the organic detrital content using k or al concentration is also proposed this resulted in the following salinity index for peat b k br k i k na k s k ge k u k and for low rank coal b k br k i k s k na k ge k u k

effect of permafrost on geochemistry in a canadian peat plateau bog permafrost is a common feature in the canadian subarctic resulting in the development of distinctive wetland forms such as peat plateaux which are perennially frozen peatlands the geochemistry of a peat plateau bog in east little bear river valley northwest territories is discussed including variations in botanical and mineralogical composition and the influence of permafrost the riparian margin of the plateau bog is unfrozen but permafrost occurs at 0 68 m depth 10 m inland cores taken in these 2 sites exhibit variations in peat stratigraphy but possess a similar c shape ash distribution in the core not affected by permafrost most elements studied al ba cr fe k mg na si th ti v also display a c shape distribution and their concentration can be explained in terms of mineral matter abundance and variety halogens cl i br on the other hand are mainly associated with the organic fraction whereas ca and se appear to be associated with both the organic and inorganic fraction in the permafrost affected core all elements independently of their organic or inorganic affinity exhibit a substantial enrichment immediately above the permafrost table whereas they are depleted immediately below this is inferred to be the result of solute redistribution linked with ice formation caused by upward permafrost growth and downward seasonal freezing