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USGS2014

Uncertainty estimates in broadband seismometer sensitivities using microseisms

The midband sensitivity of a seismic instrument is one of the fundamental parameters used in published station metadata. Any errors in this value can compromise amplitude estimates in otherwise high-quality data. To estimate an upper bound in the uncertainty of the midband sensitivity for modern broadband instruments, we compare daily microseism (4- to 8-s period) amplitude ratios between the vertical components of colocated broadband sensors across the IRIS/USGS (network code IU) seismic network. We find that the mean of the 145,972 daily ratios used between 2002 and 2013 is 0.9895 with a standard deviation of 0.0231. This suggests that the ratio between instruments shows a small bias and considerable scatter. We also find that these ratios follow a standard normal distribution ( R 2  = 0.95442), which suggests that the midband sensitivity of an instrument has an error of no greater than ±6 % with a 99 % confidence interval. This gives an upper bound on the precision to which we know the sensitivity of a fielded instrument.

Journal of Seismology↗

USGS2018

Historical sediment mercury deposition for select South Dakota, USA, lakes: implications for watershed transport and flooding

Purpose Select South Dakota, USA water bodies, including both natural lakes and man-made impoundments, were sampled and analyzed to assess mercury (Hg) dynamics and historical patterns of total Hg deposition. Materials and methods Sediment cores were collected from seven South Dakota lakes. Mercury concentrations and flux profiles were determined using lead ( 210 Pb) dating and sedimentation rates. Results and discussion Most upper lake sediments contained variable heavy metal concentrations, but became more consistent with depth and age. Five of the seven lakes exhibited Hg accumulation fluxes that peaked between 1920 and 1960, while the remaining two lakes exhibited recent (1995–2009) Hg flux spikes. Historical sediment accumulation rates and Hg flux profiles demonstrate similar peak and stabilized values. Mercury in the sampled South Dakota lakes appears to emanate from watershed transport due to erosion from agricultural land use common to the Northern Great Plains. Conclusions For sampled South Dakota lakes, watershed inputs are more significant sources of Hg than atmospheric deposition.

South Dakota↗

USGS2015

Modelling regional land change scenarios to assess land abandonment and reforestation dynamics in the Pyrenees (France)

Over the last decades and centuries, European mountain landscapes have experienced substantial transformations. Natural and anthropogenic LULC changes (land use and land cover changes), especially agro-pastoral activities, have directly influenced the spatial organization and composition of European mountain landscapes. For the past sixty years, natural reforestation has been occurring due to a decline in both agricultural production activities and rural population. Stakeholders, to better anticipate future changes, need spatially and temporally explicit models to identify areas at risk of land change and possible abandonment. This paper presents an integrated approach combining forecasting scenarios and a LULC changes simulation model to assess where LULC changes may occur in the Pyrenees Mountains, based on historical LULC trends and a range of future socio-economic drivers. The proposed methodology considers local specificities of the Pyrenean valleys, sub-regional climate and topographical properties, and regional economic policies. Results indicate that some regions are projected to face strong abandonment, regardless of the scenario conditions. Overall, high rates of change are associated with administrative regions where land productivity is highly dependent on socio-economic drivers and climatic and environmental conditions limit intensive (agricultural and/or pastoral) production and profitability. The combination of the results for the four scenarios allows assessments of where encroachment (e.g. colonization by shrublands) and reforestation are the most probable. This assessment intends to provide insight into the potential future development of the Pyrenees to help identify areas that are the most sensitive to change and to guide decision makers to help their management decisions.

Journal of Mountain Science↗

USGS2014

Hidden Markov model for dependent mark loss and survival estimation

Mark-recapture estimators assume no loss of marks to provide unbiased estimates of population parameters. We describe a hidden Markov model (HMM) framework that integrates a mark loss model with a Cormack–Jolly–Seber model for survival estimation. Mark loss can be estimated with single-marked animals as long as a sub-sample of animals has a permanent mark. Double-marking provides an estimate of mark loss assuming independence but dependence can be modeled with a permanently marked sub-sample. We use a log-linear approach to include covariates for mark loss and dependence which is more flexible than existing published methods for integrated models. The HMM approach is demonstrated with a dataset of black bears ( Ursus americanus ) with two ear tags and a subset of which were permanently marked with tattoos. The data were analyzed with and without the tattoo. Dropping the tattoos resulted in estimates of survival that were reduced by 0.005–0.035 due to tag loss dependence that could not be modeled. We also analyzed the data with and without the tattoo using a single tag. By not using.

Journal of Agricultural, Biological, and Environme↗

USGS2026

Estimating submersed aquatic vegetation biomass using a hierarchical Bayesian model of ordinal measurements and structural zeros

This study explores the prediction of a continuous target variable that is primarily measured as an ordinal outcome. Interest in such prediction may occur given data from double- or two-phase sampling designs, where an auxiliary variable is measured at all sampling units and a target and predictor variable, X , at a subset of those units. This study focuses on the case where X is nonnegative, is conditional on a zero process, and is sampled using a cluster sampling design. We model the ordinal outcome using cumulative logistic regression and the conditional regressor X , following log transformation, in a Bayesian setting. Estimation of model parameters and prediction of missing X is generally accurate and precise, particularly with sufficiently large Pr(X > 0) and associated variances. This study is motivated by a need to accurately estimate the biomass of submersed aquatic vegetation on the Upper Mississippi River, where two types of measurements for biomass are available: inexpensive, ordinal biomass scores and expensive, continuous diver-harvested biomass data. Here, X represents plant biomass and Pr(X > 0) is the usual species site occupancy measure. When fit using biomass data from the submerged aquatic vegetation species Vallisneria americana Michx, our model estimates parameters within the parameter space region where the model performed acceptably using synthetic data. We expect this model to appeal to investigators with ordered outcomes, cluster designs, and one or more continuous, positive predictors.

Journal of Agricultural, Biological and Environmen↗

USGS1981

Geological considerations in hazardous waste disposal

Present regulations assume that long-term isolation of hazardous wastes - including toxic chemical, biological, radioactive, flammable and explosive wastes - may be effected by disposal in landfills that have liners of very low hydraulic conductivity. In reality, total isolation of wastes in humid areas is not possible; some migration of leachate from wastes buried in the gound will always occur. Regulations should provide performance standards applicable on a site-by-site basis rather than rigid criteria for site selection and design. The performance standards should take into account several factors: (1) the categories, segregation, degradation and toxicity of the wastes; (2) the site hydrogeology, which governs the direction and rate of contaminant transport; (3) the attenuation of contaminants by geochemical interactions with geologic materials; and (4) the release rate of unattenuated pollutants to surface or groundwater. An adequate monitoring system is essential. The system should both test the extent to which the operation of the site meets performance standards and provide sufficient warning of pollution problems to allow implementation of remedial measures. In recent years there has been a trend away from numerous, small disposal sites toward fewer and larger sites. The size of a disposal site should be based on the attenuation capacity of the geologic material, which has a finite, though generally not well-defined, limit. For slowly degradable wastes, engineered sites with leachate-collection systems appear to be only a temporary solution since the leachate collected will also require final disposal.

Journal of Hydrology↗

USGS1993

High-pressure deformation of calcite marble and its transformation to aragonite under non-hydrostatic conditions

We conducted deformation experiments on Carrara marble in the aragonite and calcite stability fields to observe the synkinematic transformation of calcite to aragonite, and to identify any relationships between transformation and deformation or sample strength. Deformation-induced microstructures in calcite crystals varied most significantly with temperature, ranging from limited slip and twinning at 400°C, limited recrystallization at 500°C, widespread recrystallization at 600 and 700°C, to grain growth at 800–900°C. Variations in confining pressure from 0.3 to 2.0 GPa have no apparent effect on calcite deformation microstructures. Aragonite grew in 10 −6 -10 −7 s −1 strain rate tests conducted for 18–524 h at confining pressures of 1.7–2.0 GPa and temperatures of 500–600°C. As in our previously reported hydrostatic experiments on this same transformation, the aragonite nucleated on calcite grain boundaries. The extent of transformation varied from a few percent conversion near pistons at 400°C, 2.0 GPa and 10 −4 s −1 strain rate in a 0.8 h long experiment, to 98% transformation in a 21-day test at a strain rate of 10 −7 s −7 , a temperature of 600°C and a pressure of 2.0 GPa. At 500°C, porphyroblastic 100–200 μm aragonite crystals grew at a rate faster than 8 × 10 −1 m s −1 . At 600°C, the growth of aragonite neoblasts was slower, ≈6 × 10 −1 m s −1 , and formed ‘glove-and-finger’ cellularprecipitation-like textures identical to those observed in hydrostatic experiments. The transformation to aragonite is not accompanied by a shear instability or anisotropic aragonite growth, consistent with its relatively small volume change and latent heat in comparison with compounds that do display those features.

Journal of Structural Geology↗

USGS1991

Radiometric dating of quaternary deposits and the hominid mandible of Lake Banyolas, Spain

We report results of U-series analyses of the travertine matrix surrounding the Banyolas mandible that indicate an age of 45??4 ka bp. The mandible, an archaic hominid fossil generally deemed of mid-Pleistocene age, was recovered from a travertine matrix in 1887. Similar analyses on 21 travertine samples from quarries near the discovery site yield coherent U-series dates in correct stratigraphic order, ranging from 44 ka bp to 117 ka bp. Isotopic composition of these samples and the mandible matrix show no evidence of open system behaviour. Coherent isotopic results from adjacent quarries support the validity of the date on the mandible travertine, and we conclude the mandible is much younger than previously believed. ?? 1991.

Catalonia↗

USGS1977

Radioactive springs geochemical data related to uranium exploration

Radioactive mineral springs and wells at 33 localities in the States of Colorado, Utah, Arizona and New Mexico in the United States were sampled and studied to obtain geochemical data which might be used for U exploration. The major source of radioactivity at mineral spring sites is 226 Ra. Minor amounts of 228 Ra, 238 U and 232 Th are also present. Ra is presumed to have been selectively removed from possibly quite deep uranium-mineralized rock by hydrothermal solutions and is either precipitated at the surface or added to fresh surface water. In this way, the source rocks influence the geochemistry of the spring waters and precipitates. Characteristics of the spring waters at or near the surface are also affected by variations in total dissolved solids, alkalinity, temperature and co-precipitation. Spring precipitates, both hard and soft, consist of four major types: (1) calcite travertine; (2) iron- and arsenic-rich precipitates; (3) manganese- and barium-rich precipitates; and (4) barite, in some instances accompanied by S, Ra and U, if present in the spring water, are co-precipitated with the barite, Mn-Ba and Fe-As precipitates. Using parameters based on U and Ra concentrations in waters and precipitates springsite areas are tentatively rated for favourability as potential uraniferous areas.

Journal of Geochemical Exploration↗

USGS1987

Response of douglas fir (Pseudotsuga menziesii) to uraniferous groundwater in a small glaciated drainage, Northeastern Washington State

Douglas fir trees and associated soils were sampled from the slopes of a small (∼4 km 2 ) drainage basin in northeastern Washington to investigate the biogeochemical response to locally uraniferous groundwater. Uranium is preferentially incorporated in needles and twigs compared to larger branches or the trunk. The U concentration in needle ash ranges from 0.2 to 5.8μg g −1 (ppm) and shows no correlation with the U concentration in associated soils. Rather, the distribution of anomalously uraniferous douglas fir (> 1.0 μ g g −1 U in needle ash) appears to be controlled by observed or readily inferred pathways of near-surface groundwater movement in the drainage. These pathways include: (1) general downslope movement of subsurface runoff; (2) increased flux of near-surface groundwater near the toe of an alluvial fan; and (3) emergence of uraniferous (100–150 ng ml −1 [ppb] groundwater in the vicinity of a slope spring. The data also indicate the presence of near-surface uraniferous groundwater along a structurally controlled zone that parallels the north-south strike of the valley, and that includes the slope spring. The results suggest that biogeochemical sampling may be used to supplement more direct, but more limited, measurements of groundwater quality and flow regime in areas of near-surface contaminated groundwater.

Journal of Geochemical Exploration↗

USGS1991

The effect of scale on the interpretation of geochemical anomalies

The purpose of geochemical surveys changes with scale. Regional surveys identify areas where mineral deposits are most likely to occur, whereas intermediate surveys identify and prioritize specific targets. At detailed scales specific deposit models may be applied and deposits delineated. The interpretation of regional geochemical surveys must take into account scale-dependent difference in the nature and objectives of this type of survey. Overinterpretation of regional data should be resisted, as should recommendations to restrict intermediate or detailed follow-up surveys to the search for specific deposit types or to a too limited suite of elements. Regional surveys identify metallogenic provinces within which a variety of deposit types and metals are most likely to be found. At intermediate scale, these regional provinces often dissipate into discrete clusters of anomalous areas. At detailed scale, individual anomalous areas reflect local conditions of mineralization and may seem unrelated to each other. Four examples from arid environments illustrate the dramatic change in patterns of anomalies between regional and more detailed surveys.

Journal of Geochemical Exploration↗

USGS1982

Leachability of uranium and other elements from freshly erupted volcanic ash

A study of leaching of freshly erupted basaltic and dacitic air-fall ash and bomb fragment samples, unaffected by rain, shows that glass dissolution is the dominant process by which uranium is initially mobilized from air-fall volcanic ash. Si, Li, and V are also preferentially mobilized by glass dissolution. Gaseous transfer followed by fixation of soluble uranium species on volcanic-ash particles is not an important process affecting uranium mobility. Gaseous transfer, however, may be important in forming water-soluble phases, adsorbed to ash surfaces, enriched in the economically and environmentally important elements Zn, Cu, Cd, Pb, B, F, and Ba. Quick removal of these adsorbed elements by the first exposure of freshly erupted ash to rain and surface water may pose short-term hazards to certain forms of aquatic and terrestrial life. Such rapid release of material may also represent the first step in transportation of economically important elements to environments favorable for precipitation into deposits of commercial interest. Ash samples collected from the active Guatemalan volcanoes Fuego and Pacaya (high-Al basalts) and Santiaguito (hornblende-hypersthene dacite); bomb fragments from Augustine volcano (andesite-dacite), Alaska, and Heimaey (basalt), Vestmann Islands, Iceland; and fragments of "rhyolitic" pumice from various historic eruptions were subjected to three successive leaches with a constant water-to-ash weight ratio of 4:1. The volcanic material was successively leached by: (1) distilled-deionized water (pH = 5.0-5.5) at room temperature for 24 h, which removes water-soluble gases and salts adsorbed on ash surfaces during eruption; (2) dilute HCl solution (pH = 3.5-4.0) at room temperature for 24 h, which continues the attack initiated by the water and also attacks acid-soluble sulfides and oxides; (3) a solution 0.05 M in both Na,CO, and NaHCO, (pH = 9.9) at 80°C for one week, which preferentially dissolves volcanic glass. The first two leaches mimic interaction of ash with rain produced in the vicinity of an active eruption. The third leach accelerates the effect of prolonged contact of volcanic ash with alkaline ground water present during ash diagenesis.

Journal of Volcanology and Geothermal Research↗

USGS1995

Comparison of hydrothermal alteration of carboniferous carbonate and siliclastic rocks in the Valles caldera with outcrops from the Socorro caldera, New Mexico

Continental Scientific Drilling Program (CSDP) drill hole VC-2B [total depth 1761.7 m (5780 ft); maximum temperature 295 °C] was continuously cored through the Sulphur Springs hydrothermal system in the western ring-fracture zone of the 1.14 Ma Valles caldera. Among other units, the hole penetrated 760.2 m (2494.1 ft) of Paleozoic carbonate and siliciclastic strata underlying caldera fill and precaldera volcanic and epiclastic rocks. Comparison of the VC-2B Paleozoic rocks with corresponding lithologies within and around the 32.1 Ma Socorro caldera, 192 km ( 119 miles) to the south-southwest, provides insight into the variability of alteration responses to similar caldera-related hydrothermal regimes. The Pennsylvanian Madera Limestone and Sandia Formation from VC-2B preserve many of the sedimentological and diagenetic features observed in these units on a regional basis and where unaffected by high temperatures or hydrothermal activity. Micrites in these formations in VC-2B are generally altered and mineralized only where fractured or brecciated, that is, where hydrothermal solutions could invade carbonate rocks which were otherwise essentially impermeable. Alteration intensity (and correspondingly inferred paleopermeability) is only slightly higher in carbonate packstones and grainstones, low to intermediate in siltstones and claystones, and high in poorly cemented sandstones. Hydrothermal fracture-filling phases in these rocks comprise sericite (and phengite), chlorite, allanite, apatite, an unidentified zeolite and sphene in various combinations, locally with sphalerite, galena, pyrite and chalcopyrite. Terrigenous feldspars and clays are commonly altered to chlorite and seriate, and euhedral anhydrite “porphyroblasts” with minor chlorite occur in Sandia Formation siltstone. Fossils are typically unaltered, but the walls of some colonial bryozoans in the Madera Limestone are altered to the assemblage chlorite-sericite-epidote-allanite. La, Ce and Nd are present in an unidentified hydrothermal mineral occurring throughout much of the VC-2B Pennsylvanian sequence. Carboniferous carbonate and siliciclastic formations within and around the Socorro caldera show a similar style of alteration and mineralization to their Valles caldera counterparts, but by contrast locally host commercial, caldera-related, base-metal sulfide deposits. As in the Valles rocks, mineralization and alteration in those of the Socorro caldera were strongly controlled by porosity. Unless disrupted by fractures, breccias, or karst cavities ( not identified in Valles caldera drill holes), the rocks remained relatively unaltered. Where these features allowed ingress of mineralizing hydrothermal solutions, base-metal sulfides and rare-earth-element-bearing minerals were precipitated.

New Mexico↗

USGS2004

Mineral matter and potentially hazardous trace elements in coals from Qianxi Fault Depression Area in southwestern Guizhou, China

Mineralogy, coal chemistry and 21 potentially hazardous trace elements (PHTEs) of 44 coal samples from the Qianxi Fault Depression Area (QFDA) in southwestern Guizhou province, China have been systematically studied. The major minerals in coals studied are quartz, kaolinite, illite, pyrite, calcite, smectite, marcasite and accessory minerals, including rutile, dolomite, siderite, gypsum, chlorite, melanterite, apatite, collophane and florencite. The SiO2 content shows a broad variation (0.8-30.7%). A high SiO2 content in Late Permian coals reflects their enrichment in quartz. The Al2O3 content varies from 0.8% to 13.4%, Fe2O3 from 0.2% to 14.6%, CaO from <0.1% to 11.9% and the contents of other oxides are relatively low. The relationship between the major oxides and the ash content of coals from high to low is in the order of Si>Al>K>Ti>Na>Mg>Ca>Fe>S. A comparison with World coal averages shows that the Late Permian coals in QFDA are highly enriched in As, Hg, F and U, and are slightly enriched in Mo, Se, Th, V and Zn. The Late Triassic coals in QFDA are highly enriched in As and Hg, and are slightly enriched in Mo, Th and U. The concentrations of As, Hg, Mo, Se, Tl and Zn in the QFDA coal are higher than other Guizhou coal and Liupanshui coal nearby. The QFDA is an area strongly affected by the low-temperature hydrothermal activity during its geologic history (Yanshanian Age, about 189 Ma). The coals in QFDA are enriched in volatile PHTEs, including As, Hg, Se, Sb, Mo, among others. The regions where the coals are enriched in As, Hg and F have been mapped. The regions of coals enriched in volatile PHTEs overlap with the regions of noble metal ore deposits. These coals are located in the cores of anticline and anticlinorium, which are connected with the profound faults through the normal faults. Coals are enriched in volatile PHTEs as a result of the low-temperature hydrothermal activity associated with tectonic faulting. ?? 2003 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗

USGS2004

Functional group and individual maceral chemistry of high volatile bituminous coals from southern Indiana: Controls on coking

The individual maceral chemistries of two Pennsylvanian, high volatile bituminous coals, the Danville Coal Member (Dugger Formation, R o=0.55%) and the Lower Block Coal Member (Brazil Formation, R o=0.56%) of Indiana, were investigated using electron microprobe and Fourier Transform Infrared Spectrometry (FTIR) techniques, with the purpose of understanding differences in their coking behavior. Microprobe results reveal that carbon contents are highest in inertinite and sporinite, followed by desmocollinite and telocollinite. Oxygen and organic nitrogen are most abundant in telocollinite and desmocollinite; sporinite and inertinite contain lesser amounts of these two elements. Organic sulfur contents are highest in sporinite, lowest in inertinite, and intermediate in desmocollinite and telocollinite. Vitrinites within the Danville and Lower Block coals are very similar in elemental composition, while Lower Block inertinites and sporinites have higher carbon, lower oxygen, and sulfur contents which, when combined with the inertinite-and sporinite-rich composition of the Lower Block seam, strongly influences its whole coal chemistry. Fourier transform infrared spectrometry revealed greater aromatic hydrogen in the Lower Block coal, along with higher CH2/CH3 ratios, which suggest that liptinites contribute considerable amounts of long-chain, unbranched aliphatics to the overall kerogen composition of the Lower Block coal. Long-chain, unbranched aliphatics crack at higher temperatures, producing tar and oily byproducts during coking; these may help increase Lower Block plasticity. Electron microprobe and FTIR results indicate that individual maceral chemistries, combined with the maceral composition of the seam, are the primary control of better coking properties of the Lower Block coal. ?? 2003 Elsevier B.V. All rights reserved.

International Journal of Coal Geology↗

USGS2006

Petrology and chemistry of Permian coals from the Paraná Basin: 1. Santa Terezinha, Leão-Butiá 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 Paraná 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 Leão-Butiá 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 SiO 2 and Al 2 O 3 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 Paraná 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, Paraná 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 Leão-Butiá 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.

International Journal of Coal Geology↗

USGS2010

Coal lithotypes before and after saturation with CO2; insights from micro- and mesoporosity, fluidity, and functional group distribution

Four lithotypes, vitrain, bright clarain, clarain, and fusain, were hand-picked from the core of the Pennsylvanian Springfield Coal Member (Petersburg Formation) in Illinois. These lithotypes were analyzed petrographically and for meso- and micropore characteristics, functional group distribution using FTIR techniques, and fluidity. High-pressure CO2 adsorption isotherm analyses of these lithotypes were performed and, subsequently, all samples were reanalyzed in order to investigate the effects of CO2. After the high-pressure adsorption isotherm analysis was conducted and the samples were reanalyzed, there was a decrease in BET surface area for vitrain from 31.5m2/g in the original sample to 28.5m2/g, as determined by low-pressure nitrogen adsorption. Bright clarain and clarain recorded a minimal decrease in BET surface area, whereas for fusain there was an increase from 6.6m2/g to 7.9m2/g. Using low-pressure CO2 adsorption techniques, a small decrease in the quantity of the adsorbed CO2 is recorded for vitrain and bright clarain, no difference is observed for clarain, and there is an increase in the quantity of the adsorbed CO2 for fusain. Comparison of the FTIR spectra before and after CO2 injection for all lithotypes showed no differences with respect to functional group distribution, testifying against chemical nature of CO2 adsorption. Gieseler plastometry shows that: 1) softening temperature is higher for the post-CO2 sample (389.5??C vs. 386??C); 2) solidification temperature is lower for the post-CO2 sample (443.5??C vs. 451??C); and 3) the maximum fluidity is significantly lower for the post-CO2 sample (4 ddpm vs. 14 ddpm). ?? 2010 Elsevier B.V.

International Journal of Coal Geology↗

USGS2010

Depositional setting, petrology and chemistry of Permian coals from the Paraná Basin: 2. South Santa Catarina Coalfield, Brazil

In Brazil economically important coal deposits occur in the southern part of the Paraná Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata , and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paraná Basin. In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment , with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapuá, Barro Branco and Treviso seams). Seam thicknesses range from 1.70 to 2.39 m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapuá seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapuá seam has the highest inertinite content (33.8 vol%). Liptinite mean values range from 7.8 vol% (Barro Branco seam) to 22.5 vol% (Irapuá seam). Results from proximate analyses indicate for the three seams high ash yields (50.2 – 64.2 wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (> 50 wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the predominance of quartz and kaolinite (also pyrite). Gypsum , gibbsite , jarosite and calcite were also identified in some samples. Feldspar was noted but is rare. The major element distribution in the three seams (coal basis) is dominated by SiO 2 (31.3 wt.%, mean value), Al 2 O 3 (14.5 wt.%, mean value) and Fe 2 O 3 (6.9 wt.%, mean value). Considering the concentrations of trace elements that are of potential environmental hazards the Barro Branco, Bonito and Irapuá seams (coal base) are significantly enriched in Co (15.7 ppm), Cr (54.5 ppm), Li (59.3 ppm), Mn (150.4 ppm), Pb (58.0 ppm) and V (99.6 ppm), when compared to average trace elements contents reported for U. S. coals. Hierarchical cluster analysis identified, based on similarity levels, three groups of major elements and seven groups of trace elements. Applying discriminant analyses using trace and major element distribution, it could be demonstrated that the three seams from Santa Catarina show distinct populations in the discriminant analyses plots, and also differ from the coals of Rio Grande do Sul analyzed in a previous study.

Santa Catarina↗