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Coal mining can generate organic and inorganic contaminants that can be disseminated in the surrounding soils by leaching and/or aerial deposition. This study aims to identify and characterize the physicochemical and geochemical changes promoted in soils from the surrounding area of a self-burning waste pile in an abandoned coal mine. A soil sampling campaign was conducted bordering the waste pile, comprising the main drainage areas as well as the areas uphill. The soils were characterized geochemically for major and trace elements and multivariate statistics was used in combination with geostatistical methodologies to study the statistical and spatial relations of the different elements and infer their Potentially Toxic Elements (PTEs) sources. The 16 priority Polycyclic Aromatic Hydrocarbons (PAHs) were identified and quantified in soils according to their spatial distribution, and their pyrogenic/petrogenic sources were inferred. Different sources were identified as contributing to the soil geochemical signature, considering not only the mine but also anthropogenic urban contamination or naturally enhanced regional geochemical background in multiple PTEs. PAHs tend to concentrate downstream of the waste pile, along the runoff areas, presenting a greater variety of the 16 priority PAHs and an increase of High Molecular Weight (HMW) PAHs pointing to its pyrogenic origin, possibly related to the self-combustion phenomenon occurring in the waste pile.

The coal mining residues from past mining activities in the Douro Coalfield are emplaced in many dumps near the mining areas, causing substantial environmental impacts. This study aims to contribute to the investigation of environmental impacts caused by the disposal of the residue in the Douro Coalfield through the determination of the geochemical composition of waste materials collected at 3 – 15 m depth, and of the water-leachable fraction produced by percolation in these materials inside the dump. The elements with higher concentration in the leachates are Ca, Cd, Co, Mg, Mn, Na, Ni, S, and Zn, indicating that they are the most easily leached and accessible elements for percolation and mobilization into the environment. The presence of these elements in the leachates is principally attributed to their occurrence as water-soluble ions in clays and sulphides affected by natural weathering conditions, which promotes their breakdown and occurrence as exchangeable ions. The leachates are classified as acid high-metal. Natural weathering and leaching in the Sao Pedro da Cova waste dump are the principal paths for chemical elements to be percolated and mobilized to environment, posing risk to the soils, waters and ecosystems in the surrounding areas.

The investigation about wildfires has demonstrated that research should include studies on the overall assessment of the processes, thus promoting the public awareness about impacts. The aim of this study is to assess the changes on the carbon content of soils affected by wildfires in Caramulo Mountain (Portugal) to therefore identify the environmental impacts arisen from those changes. Soils from different parent rocks, affected and non-affected by wildfires, were collected. Petrographic and geochemical methods were used to identify changes caused by the wildfires in the organic fraction of soils. The results demonstrate that changes in soils composition after wildfires include the production of charcoal and pyrogenic polycyclic aromatic hydrocarbons (PAH). The incorporation of charcoal from biomass burning in soils overtime and the production of pyrolytic PAH are of environmental concern since these compounds are known to be harmful to the environment and ecosystems and are human carcinogens. The concentration of BkF-benzo[k]fluoranthene, known as probable human carcinogen, exceeds the reference values for contaminated soils. Once in soils these compounds can be removed by percolation affecting waters and, consequently, biodiversity and human health. This work was developed under the ICT (project UIDB/04683/2020) with the reference POCI-01-0145-FEDER-007690. info:eu-repo/semantics/publishedVersion

The Douro Carboniferous Basin (DCB), aged from Gzhelian, is an important coal‐bearing basin occurring in Northern Portugal. While the coals and the sedimentary sequence of the DCB have been deeply studied, the inorganic geochemical data are scarce. This study intends to provide major and trace element contents and discuss their modes of occurrence and origins using a set of twenty‐four coal samples from the São Pedro da Cova Coalfield taken from different sectors/outcrops. Thus, an integrated approach using petrographic, geochemical, both organic and inorganic, and mineralogical data was used to achieve these purposes. The main results demonstrated that these coals are anthracite A and vitrinite is the main organic component. Most of the elements have inorganic affinities and are associated with aluminosilicates, while the other elements have affinities with sulfides. Illite and muscovite are the main phyllosilicates occurring in these coals and pyrite is the most common sulfide. However, cinnabar, together with phosphates (fluorapatite, monazite, xenotime and gorceixite), were also identified. The enrichment of most elements as well as a heterogenous rare earth elements (REE) distribution pattern in the tectono-sedimentary unit (TSU) samples are related to magmatic fluids. On the other hand, on the Eastern Outcrop (EO), a tectonic slice, the subparallel trend of the REE distribution patterns, and a depletion of all the elements are related to the sedimentary contribution. The occurrence of cinnabar and gorceixite epigenetic mineralizations is interpreted as the action of a porphyry intrusion identified in this area of the DCB, between the TSU B1 and TSU D1., The author H. Moura benefited from a doctoral scholarship financed by the FCT—Fundação para a Ciência e a Tecnologia (Ref: SFRH/BD/ 134109/2017).

The target of this study was the tungsten Regoufe mine, whose exploitation stopped in the 1970s. When the mine closed, an unacceptable legacy constituted of mining waste tailings and the ruins of infrastructure was left behind. This work assessed the soil, plants, and water contamination in the mining area; namely their content in potentially toxic elements (PTEs). The global impact of PTEs in the Regoufe mine surface soil points to a very high to ultrahigh degree of contamination of the area having a serious ecological risk level, mainly related to As and Cd contributions. However, establishing the direct relation between As contamination and the anthropogenic effects caused by the mining process cannot be carried out in a straightforward manner, since the soils were already enriched in metals and metalloids as a result of the geological processes that gave origin to the mineral deposits. The studies performed on the plants revealed that the PTE levels in the plants were lower than in the soil, but site-specific soil concentrations in As and Pb positively influence bioaccumulation in plants. The magnetic studies showed the presence of magnetic technogenic particles concentrated in the magnetic fraction, in the form of magnetic spherules. The magnetic technogenic particles probably result from temperature increases induced by some technological process related to ore processing/mining activity. The PTEs in the surface and groundwater samples were similar and relatively low, being unlikely to pose potential health and environmental risks. Arsenic (As) constituted the exception, with levels above reference for drinking water purposes.

Two water effluents that drain from the abandoned coal mine of São Pedro da Cova (NW Portugal) were characterized in terms of their physic-chemical properties and suitability for irrigation purposes. Samples were also collected in a local surface stream, upstream and downstream from the mine drainage points, also used for irrigation by local farmers. Water samples were analyzed for major and minor ions and for trace element concentrations. Sampling campaigns started in 2017 and ended in 2019 and there were 46 water quality parameters tested. There were also proposed all-inclusive indices (the Water Quality Index and the Contamination Index, and also the Trace Element Toxicity Index) based on specific groups of 18 and 17 physic-chemical parameters, respectively, to achieve adequate monitoring requirements for mine effluents and surface water from coalfield. From the physical and chemical aspects of mine water it is inferred that the mine is not producing acid mine drainage. The coal mine water is of medium to high salinity, having almost neutral pH and a high thermal stability during the year, which is a distinguishing feature of the effluents. When compared to international irrigation water quality standards, as Food and Agriculture Organization of the United Nations admissible concentrations, the impacted waters are unsuitable for irrigation. The major outliers to the guidelines were iron, manganese, potassium, magnesium and bicarbonates, being also detected carcinogenic polycyclic aromatic hydrocarbons. Cost-effective ways of monitoring water quality parameters are needed to help control and manage the impact of coal mine effluents that should be treated before releasing into a ditch system that could be then used by local farmers to irrigate their crops.

This study aims to demonstrate, by a detailed fundamental analysis, an alternative for the production of rare earth elements, including yttrium and scandium (REY + Sc), from the historic bottom ash deposit at Ceplea Valley (Romania). Twenty-five samples representing 20% of this deposit were studied using a combination of chemical (proximate and elemental analysis), mineralogical and petrographic techniques. This analysis also included, for the first time, a scanning electron microscopy with X-ray microanalysis SEM/EDS point-count method for tracking REE-bearing minerals. The results showed that the bulk REY + Sc concentration is consistent throughout the landfill, and a bottom ash composite sample was made to assess the chemical composition of several size fractions. Based on Seredin-Dai's criteria (Seredin and Dai, 2012), the plot of the outlook coefficient of REY ores (Coutl) versus the percentage of critical REY of the deposit samples (278 ppm in average) and of the composite sample size fractions shows that this ash is a potentially promising source of REY. However, Gd seems to be the most-promising element, especially in the 0.090–0.125 mm and Finally, the SEM/EDS results show that the only REE-bearing minerals (except one case with Y, Gd, Er, Dy) are micrometre-sized phosphate grains with Ce, La and Nd, with an average diameter of 4.85 μm, which do not entirely account for the total REE determined by ICP-MS and indicates that a fraction of these elements must be dispersed in the glassy aluminosilicate matrix.

The São Pedro da Cova waste pile (Porto, Portugal) is composed of coal mining residues that have been self-burning since 2005 and is located close to an inhabited area and social infrastructures, further adding to effects on the environment and human health. Therefore, there is a great interest in the environmental monitoring of this waste pile. This work describes an integrative multi-approach that allows the environmental monitoring of several parameters of the waste pile, applying several technologies. The temperature measurements were obtained by a thermal infrared (TIR) sensor on board an unmanned aerial vehicle (UAV) and supplemented with field measurements. In order to evaluate the altimetric variations, for each flight, a digital elevation model (DEM) was generated considering a multispectral sensor also on board the UAV. The hydrogeochemical characterization was performed through the analysis of groundwater and surface water samples, with and without the influence of mine drainage. The soil monitoring included the analysis of waste material as well as the surface soil in the surrounding area of the waste pile. All the data were analyzed and integrated in a geographical information system (GIS) open-source application. The adopted multi-approach methodology, given its intrinsic interdisciplinary character, has proven to be an effective way of encompassing the complexity of this type of environmental problem.

The study of coals affected by magmatic intrusions is important from a geological point of view, in order to understand how heat and magmatic fluids could affect the organic and inorganic fractions as well as the properties of the coals. These fluids may lead to an enrichment of trace elements and heavy metals of environmental concern or serve as unconventional sources of critical elements. Therefore, the objective of this study is to investigate the organic and inorganic fractions of Peñarroya-Belmez-Espiel Basin (PBEB) (Spain) coals in order to verify whether changes of the petrography, chemical composition, mineralogy, and inorganic geochemistry have taken place. The PBEB corresponds to a Carboniferous intramontane basin filled with a Middle Mississippian to Lower-Middle Pennsylvanian sedimentary succession with coal-bearing units. Two main successive depocentres (extended from NW to SE) were recognized and in which bituminous and anthracite coals, as well as natural cokes occur. Petrographic analysis, ultimate and proximate analysis, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) analysis, inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) analysis were carried out for the purpose of this study. The sampling consisted of a selected set of nine samples of bituminous coals, ten samples of anthracites and three samples of natural cokes. The results show that the organic fraction of bituminous and anthracite coals is mainly made up of vitrinite. Although the minerals identified in the two depocentres vary, they mainly consist of quartz and clay minerals in both cases. Authigenic kaolinite and epigenetic mineralization related to thermal events that occurred in the basin were observed in the anthracites. Natural coke shows isotropic and fine mosaic textures, and signs of epigenetic mineralization. The trace element content of the coal samples was compared with the values established for world hard coals and an enrichment of Cs, in bituminous and anthracite coals, and of Hg in natural cokes, was observed. The occurrence of REY in bituminous coals is related to the detrital sedimentary source, whereas in anthracite the epigenetic and thermal effects may have also been involved. In natural cokes, the REY content is probably associated with the original coal. Mercury enrichment in natural cokes may be associated with magmatic fluids and explained by Hg volatilization, its capture in natural coke pores and subsequent precipitation., The author H. Moura benefited from a doctoral scholarship financed by the FCT - Fundação para a Ciência e a Tecnologia (Ref: SFRH/BD/134109/2017). This work was financed by national funds through FCT - Fundação para a Ciência e a Tecnologia, I.P., under the project Ref. UIDB/04683/2020.

The Sao Pedro da Cova (Portugal) coal mine produced a significant volume of waste deposited in different piles that have been on self-burning, continuously, for the past 15 years, increasing regional environmental concerns. Attempting to study and monitor the combustion phenomenon in these waste deposits, periodic measurements have been made using multiple sensors on-board of an unmanned aerial vehicle (UAV) and also in situ measurements. Assessments from RGB camera, thermal infrared and multispectral sensors, in addition to the geostatistical analysis of the in situ data, confirmed that the self-burning process is still active. Furthermore, the UAV methodology applied seems adequate for steep settings with difficult accessibility, as well as allowing for a better understanding and monitoring of the overall progression and state of the waste piles' self-burning process.

The Sao Pedro da Cova coal mine, in Gondomar (Portugal), left a substantial ecological footprint in the form of a 28,000 m2 waste pile. This waste pile has been undergoing continuous self-combustion since 2005, leading to the mobilization of pollutants. As a result, it is of vital importance to monitor the condition and evolution of the waste pile, to assess the current and potential risks posed to the inhabitants and to propose adequate mitigation measures. To evaluate and monitor the waste pile surface soil movements, a comparison between different digital elevation models (DEM) was performed. The DEMs were obtained from photogrammetric processing of data collected by different sensors onboard of an unmanned aerial vehicle (UAV). As preliminary results, the waste pile seems to be suffering a generalized topographic recession, verified by the elevation decrease on multiple monitoring points, this effect may be caused by soil erosion or subsidence, potentially caused by the coal fires that have been active in this waste pile. As part of a larger evaluation of the study area within the CoalMine Project, which includes geochemical soil and water analysis, as well as, monitoring of the surface temperatures, the current assessment of soil movement provides crucial insight into the movement and deposit of soil in addition to the potential contaminants present in its composition.

The investigation about wildfires has demonstrated that research should include studies on the overall assessment of the processes, thus promoting the public awareness about impacts. The aim of this study is to assess the changes on the carbon content of soils affected by wildfires in Caramulo Mountain (Portugal) to therefore identify the environmental impacts arisen from those changes. Soils from different parent rocks, affected and non-affected by wildfires, were collected. Petrographic and geochemical methods were used to identify changes caused by the wildfires in the organic fraction of soils. The results demonstrate that changes in soils composition after wildfires include the production of charcoal and pyrogenic polycyclic aromatic hydrocarbons (PAH). The incorporation of charcoal from biomass burning in soils overtime and the production of pyrolytic PAH are of environmental concern since these compounds are known to be harmful to the environment and ecosystems and are human carcinogens. The concentration of BkF-benzo[k]fluoranthene, known as probable human carcinogen, exceeds the reference values for contaminated soils. Once in soils these compounds can be removed by percolation affecting waters and, consequently, biodiversity and human health.

The self-burning of coal mining residues disposed at environmental conditions have been described in the literature as a phenomenon occurring worldwide. These coal related fires are of significant concern because of the risks to environment and human health due to the emission of harmful gases and particulate matter to atmosphere. Another concern is the degradation of soils and waters in surrounding areas owing to the mobilization and leaching of hazardous elements. The self-burning of coal mining waste deposits may be a very persistent phenomena over decades. The carbon content (combustible fraction) and chemical composition of coal waste materials (and some physical properties) are the most relevant factors that influence intensity and duration of the self-burning process. The comprehensive characterisation of coal waste deposit materials provide information on the self-burning process and above all useful insights about the propensity to ignition and burning and their environmental impacts. The characterization of coal waste materials can contribute to assess their reuse as a secondary source of critical raw materials and carbon based materials.The recycling of these materials, from both burning and non-burning coal waste deposits, is in good agreement with recommendations from European Union (EU) pointing out the need for developing sustainable recovery of mining and industrial wastes to mitigate environmental impacts. The EU identifies 26 critical raw materials including inorganic trace elements and natural graphite as a critical raw materials with extremely high level of external dependence, and strongly recommends the development of measures to increase recycling of by-products and residues. In this framework, research has been dedicated to burning or already burned coal mining waste deposits in Portugal and Spain. Non-burning coal mining waste deposits from the same mining areas have also been investigated. These coal waste deposits, resulted from the discharging of coarse mine refuse from mining exploration. They are very heterogeneous and present variable amounts of coal that is the combustible fraction. The comprehensive characterization of mining waste materials as well as the identification of products formed during combustion reveals the potential environmental impact, principally due to the concentration of volatile organic compounds emitted to atmosphere. The combustion process also causes changes in trace elements’ mode of occurrence with some becoming more easily mobilised for surrounding soils and water systems by percolation or deposition of solid atmospheric particles. On the other hand, the mining waste burned materials reveal an enrichment of some trace elements, including critical raw material; and, the production of graphitic structures, including graphene. Therefore the coal wastes mining deposits are an environmental issue, they can be seen as an alternative secondary source of critical raw materials and carbon based materials.

Self-heating of coal waste is a major problem in the leading coal-producing and consuming countries, independent of the recent or past coal exploitation history. The phenomenon of self-heating is dependent on many factors such as the properties of organic matter (maceral composition and rank), moisture and pyrite content, climate effects, and storage conditions (shape of the dump or compaction of the coal waste). Once deposited, coal waste undergoes oxidation, which can lead to self-heating with the overall temperatures exceeding 1000 °C. During these self-heating processes, both organic and mineral matter undergo oxidative and thermal alterations, being influenced, among others, by the rate of heating as well as by the access of air and moisture. The morphological features of organic matter in coal waste at microscopic scale reflect the thermal conditions within the waste dump. Since 2008, several exercises designed to establish a petrographic classification system of oxidatively- and thermally-altered morphological forms of organic particles present in self-heated coal waste dumps have been carried out within the Self-heating of Coal and Coal Waste Working Group (Self-Heating WG), in Commission III of the International Committee for Coal and Organic Petrology (ICCP). Based on the degree of oxidative and thermal alteration, all assessed organic particles were divided into unaltered particles (huminite, vitrinite, liptinite, and inertinite macerals), altered particles, and newly formed particles (pyrolytic carbon, bitumen, chars, graphite, and coke). Altered particles were further divided according to their optical properties (porous, massive; isotropic, anisotropic). For altered particles the following specific features were distinguished: fractures, fissures, cracks; brighter rims; darker rims; plasticised edges; bands; devolatilisation pores; paler in colour particles. The final petrographic classification of oxidatively- and thermally-altered morphological forms of organic particles in coal waste dumps was established as a result of the successively performed Round Robin Exercises 2008–2017. The selected criteria and categories proved the high performance of the analysts characterised by a minor bias. The proposed petrographic classification system based on petrographic methods represents a useful way to characterize the undesirable phenomena occurring in coal waste dumps. Microscopic analyses and application of the petrographic classification system for organic particles affected by self-heating in coal waste offers the identification, documentation and monitoring of coal waste oxidation, self-ignition and combustion processes. It also enables a selection and application of appropriate measures to delay or even prevent undesired environmental impacts. The established classification system may assist in the air quality monitoring and assessment of burning waste dump sites and, thus, provide a relevant support in the environmental management of the disposal sites related to coal mining. The classification system can provide an important instrument for environmental protection agencies to increase the effectiveness of measures applied in fire hazard combating. The proposed classification of oxidatively- and thermally-altered morphological forms of organic particles in coal waste dumps can be applied on self-heating coal waste or mining dumps research, being a useful tool for coal waste managements performed by environmental agencies responsible for the landfill managements and monitoring of waste dumps., The samples used for preparation of the Round Robin Exercises within the Self-heating Working Group of the ICCP were obtained within the framework of the grants 2011/03/B/ST10/06331 and N307 016 32/0493 acquired by Magdalena Misz-Kennan from the National Center of Science, Poland. The research work conducted by Jolanta Kus within the Self-heating Working Group of the ICCP was supported and is published with the permission of the Federal Institute for Geosciences and Natural Resources, Hannover, Germany.

The Mozambique Basin, which occurs onshore and offshore in the central and southern parts of Mozambique, contains a thick sequence of volcanic and sedimentary rocks that range in age from the Jurassic to Cenozoic. This basin, along with the Rovuma basin to the north, has been the main target for hydrocarbon exploration; however, published data on hydrocarbon occurrences do not exist. In this context, the present study aims to contribute to the understanding of the nature of the organic matter of a sedimentary sequence intercepted by the Nemo-1X exploration well located in the offshore area of the Mozambique Basin. The well reached a depth of 4127 m, and 33 samples were collected from a depth of 2219–3676 m ranging in age from early to Late Cretaceous. In this study, petrographic and geochemical analytical methods were applied to assess the level of vitrinite reflectance and the organic matter type as well as the total organic carbon, total sulfur, and CaCO3 contents. The results show that the total organic carbon content ranges from 0.41 to 1.34 wt%, with the highest values determined in the samples from the Lower Domo Shale and Sena Formations, which may be related to the presence of the solid bitumens that occur in the carbonate fraction of those samples. The vitrinite random reflectances range from 0.65 to 0.86%Rrandom, suggesting that the organic matter in all of the samples is in the peak phase of the “oil generation window” (0.65–0.9%Rrandom). The organic matter is mainly composed of vitrinite and inertinite macerals, with a minor contribution of sporinite from the liptinite group, which is typical of kerogen type III. Although all of the samples have vitrinite reflectances corresponding to the oil window, the formation of liquid hydrocarbons is rather limited because the organic matter is dominated by gas-prone kerogen type III.

Organic petrology is an important tool used to characterize dispersed organic matter (DOM) in sediments and sedimentary rocks, and to assess its thermal maturity. This study was carried out on 33 cutting samples (Middle-Upper Jurassic) from the Ramalhal-1 well to characterize the particulate organic matter and to evaluate its thermal maturity. The samples were submitted to optical petrography analysis (reflected white and blue incident lights) and the mean random reflectance was measured. Microscopic observations revealed a low DOM content, characterized by the predominance of macerals of the inertinite group (including charcoal), followed by solid bitumen. Huminite/vitrinite is usually small in size and quantity. Liptinite macerals were also present, represented by sporinite, cutinite, liptodetrinite and rare bituminite. A type III-IV kerogen was defined for the Ramalhal-1 sequence. Huminite/vitrinite mean random reflectance varied between 0.38% and 0.75%, pointing to an immature-to-mature stage of the organic matter. Multi-populations of solid bitumen occurred in almost all the samples, filling voids and fractures in the inorganic materials (mainly carbonates). The bitumen populations were quite heterogeneous, concerning both the optical characteristics and distribution, displaying different thermal maturities. No relationship between vitrinite and bitumen reflectance was established, indicating that these bitumens were not generated in situ.

Gaiteiros-1 borehole, located in the central Lusitanian Basin (Portugal), drilled a continuous Jurassic (Hettangian to Kimmeridgian) sedimentary sequence. Forty-one samples were selected for this study to characterize the dispersed organic matter and its vertical variation along Gaiteiros-1 borehole and to evaluate the environmental changes based on palynofacies and bulk geochemistry analyses. Gaiteiros-1 borehole lithological sequence is characterized by a low organic carbon content, which varies between 0.10 wt% and 0.83 wt%, in Candeeiros carbonates and Lower Jurassic Coimbra Formation, respectively. The insoluble residue content indicate a carbonated character in almost the entire sequence, except for Kimmeridgian samples. The palynofacies analysis evidences the presence of the main groups of kerogen (Phytoclats, Amorphous and Palynomorphs) with a dominance of the amorphous group in the carbonated samples and phytoclasts in Kimmeridgian detritic samples. Different types of amorphous particles were identified, suggesting periods of reworking by bacterial activity and primary bioproductivity in depleted oxygen environments. Despite the dominance of amorphous particles, the kerogen groups vertical variation provides information that reveals changes in the depositional environment. The kerogen assemblage of the Candeeiros facies suggests a stratified water column, with well-oxygenated layers, responsible for high primary productivity periods, which allowed for the development of zooplankton, preserved in the form of zooclasts fragments and foraminiferal test-linings. The contribution of the Palynomorph group is scarce during the Lower-Middle Jurassic but increases in the Upper Jurassic. This modification in the kerogen assemblage reflects changes in the sea level, oxygenation conditions, climate and proximity to the terrestrial source area. The presence of Coleochaete-like freshwater algae was detected for the first time in the Lusitanian Basin, suggesting more restrictive conditions during the Late Oxfordian. During the Kimmeridgian, the amorphous material disappears and phytoclasts, mainly opaque phytoclasts, come to dominate the kerogen assemblage, as a result of terrigenous sediments input, due to the great proximity to the terrestrial source area.

This paper presents a taxonomic revision of the fossil-genus Ilfeldia Remy and establishes the fossil-genus Ovulepteris nov. Three species of Ilfeldia ( Ilfeldia jejunata , Ilfeldia gregoriensis nov. sp. and Ilfeldia polysporangiata comb. nov.) have been identified in Europe from localities in the Douro Basin (Portugal), Ilfeld Basin (Germany) and at Manebach (Germany). The stratigraphic distribution of the fossil-genus varies from Gzhelian (Carboniferous) ( I. jejunata and I. gregoriensis sp. nov.) to lower Asselian (Permian) ( I. polysporangiata comb. nov.). All species of Ilfeldia are associated with larger taeniopterid leaves that could potentially be sterile equivalents due to dimorphism, and sterile and fertile leaves have been found in organic connection in I. gregoriensis sp. nov. Ilfeldia may be affiliated with the ferns or pteridosperms, but the systematic position is unclear. Ovulepteris gen. nov., which is established for leaves that bear ovule-type reproductive organs, has oblong leaves with a partly reduced leaf lamina, with reproductive organs situated on the leaf margin. The concept of Ovulepteris gen. nov. is based on material originally described by Obrhel (1957, 1965) under the names Ilfeldia robusta Obrhel and Ilfeldia lobecensis Obrhel from the Pennsylvanian of the Czech Republic. The new combinations Ovulepteris robusta (Obrhel) comb. nov. and Ovulepteris lobecensis (Obrhel) comb. nov. are established herein. Ovulepteris gen. nov. differs from Sobernheimia in the style of placement of the seeds. In Ovulepteris gen. nov., seeds are situated at the end of veins in protruding segments, whereas their attachment in Sobernheimia is uncertain but appear to be attached to the “midrib”. The diagnosis of Ovulepteris gen. nov. is not identical with the diagnoses of existing genera that have leaves with ovules, necessitating establishment of this new fossil-genus. The systematic position of all fossil-genera studied herein is uncertain, although they appear to be a member of the pteridosperms.

The El Bierzo is the largest and westernmost Stephanian coalfield in the Cantabrian mountain range (northwest of Spain), and mining activity has generated waste dumping over vast areas of the original soil. The mining waste deposits have been exposed to natural alterations that have caused the production of mining acid drainage and the spontaneous combustion of coal waste piles (CWP), which in turn have an environmental impact on the air, water, soil, and vegetal and animal life of the surrounding area. The identification and characterization of the effects caused by coal waste deposits in the riverine system of the region of Fabero of the El Bierzo coalfield are the main goals of this study. Water samples from the Cua River and its tributaries in the region (Galladas, Mourin, and Lamocos tributaries) were collected in two different periods of the year (wet and dry seasons). For the physicochemical characterization of water samples the following analyses were performed: pH and ionic conductivity measurements; the determination of the carbon concentration by the catalytic oxidation combustion; the evaluation of the chloride, nitrates, and sulfate anion concentrations by ion chromatography; and determination of the trace element concentrations by means of inductively coupled plasma mass spectrometry. Some physicochemical parameters of the water samples evidenced the production of acid mine drainage as the result of the circulation of waters through the coal waste deposits, which promoted the dissolution of metals. The results indicate that the physicochemical characteristics of the waters collected in the areas upstream of the coal waste deposits and old mining infrastructures are less affected by the circulation of waters through those materials. On the other hand, the samples collected downstream of the coal waste deposits and old mining infrastructures present the highest trace element concentration, a lower pH, a higher conductivity, and a higher sulfate concentration, as the result of the circulation of waters through these materials. To investigate the quality of the water streams in the region of Fabero, the chemical composition of the studied waters was compared with previous studies on the quality of groundwater in the El Bierzo area and other information about acid mining drainage waters in other coal mining regions, as well as guideline values from water quality legislation. These comparisons point out the presence of certain metallic species (i.e., Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and their likely environmental impact on the riverine system in the Fabero mining area. To identify the probable source of the enriched elements detected in the studied water samples, their chemical composition was compared with the chemical composition of the solid materials from the CWP that had percolated into the studied tributaries. The comparison indicates that the percolation of waters through the Arroyo Galladas CWP caused the dissolution of toxic metals (specifically Mn, Ni, Zn) under acidic conditions, leading to high concentrations of these metallic species in the water samples.

A Pleistocene coastal lignite outcropping between the Muândeje Lake (Maputo Province)and Nhachuendezo Lake (Gaza Province)was recognized during geological mapping performed in 2009. However, these outcrops started to be investigated only in 2017 through paleontological fieldwork under the PaleoMoz Project (www.paleomoz.org). Here the chemical and petrographic compositions of a coal sample from this locality are reported. This new occurrence represents the first lignite occurrence from coastal Mozambique. The lignite is a Low Rank C (Lignite C)coal with a huminite reflectance of 0.248%. The results show that the lignite has high ash yield (46.5%, d); volatile matter (65.2%, daf), carbon (57.3%, daf), hydrogen (5.3%, daf)and nitrogen (2.3%, daf)contents are according to the rank of this coal; and, low total sulphur (1.8%, d). The coal is richer in huminite (86%)than liptinite (10%)and inertinite (4%). The maceral analysis indicates that lignite's peat precursor derived mainly from herbaceous plants and Botryococcus algae deposited in a topogenous mire (fen)under mesotrophic anoxic conditions. The water level remained above the paleomire's surface., This work was developed under the auspices of PaleoMoz Project (funded by Museu Nacional de Geologia, Programa Aga-Khan/Fundação para a Ciência e Tecnologia and National Geographic Society Standard Grant CP-109R-17). RA would additionally like to acknowledge additional funding through Fundação para a Ciência e a Tecnologia (SFRH/BPD/96205/2013). D. Flores acknowledges the funding provided by the Instituto de Ciências da Terra, Polo Universidade do Porto, through the contracts UID/GEO/04683/2013

The current and future importance of coal as a geological resource is related with the production of coke, carbon materials, carbon derivatives and other chemical products as well as a promising alternative source of critical trace elements. This study aims the comprehensive characterization of coals from the Santa Susana Basin (SSB), SW of Portugal. The SSB is a Pennsylvanian continental basin located along the Santa Susana Shear Zone that separates two tectonostratigraphic zones of Iberian Massif. Samples of coal and coaly silt-claystone from the main outcrops, Jongeis and Vale de Figueira, were collected for this study. The methodologies used for the petrographic and geochemical characterization included: optical microscopy, scanning electron microscopy with energy dispersive X-ray spectrometry, proximate and elemental analysis and inductively coupled plasma mass spectrometry (ICP-MS). The results demonstrate that the organic matter of coal from SSB is essentially composed of vitrinite and small amounts of inertinite. The mineral matter includes detrital minerals (mainly quartz and clay minerals), iron oxides and oxidized and non-oxidized framboidal pyrite. Epigenetic carbonates (dolomite and ankerite) were only observed in samples from Jongeis outcrop. Vitrinite random reflectance of the samples ranges between 0.90% and 1.25%, indicating a bituminous coal rank. The slightly higher vitrinite reflectance and the occurrence of epigenetic carbonates in samples from Jongeis can be related with differentiated burial history of the basin and post-depositional processes including fluids circulation that may have promoted the enhancement of the thermal maturity. When compared with the geochemical composition of worldwide hard coals, samples from Vale de Figueira are significantly enriched in Cs and In, while samples from Jongeis are significantly enriched in In and Mn. Considering the elements’ mode of occurrence, the majority of elements are preferentially associated with mineral matter. The elements S, Cd, Mo, Pb and Se have organic affinity. The strong positive correlation between Ca and Mg, Mn and Te indicates their association with carbonate phases, which is in accordance with the carbonate composition., The authors acknowledge the funding provided to Institute of Earth Sciences through the contracts UID/GEO/04683/2013 with FCT and COMPETEPOCI-01-0145-FEDER-007690. This work is a contribution to the project ALT20-03-0145-FEDER-000028, funded by Alentejo 2020 through the FEDER/FSE/FEEI.

An interlaboratory study (ILS) was conducted to test reproducibility of vitrinite and solid bitumen reflectance measurements in six mudrock samples from United States unconventional source-rock reservoir petroleum systems. Samples selected from the Marcellus, Haynesville, Eagle Ford, Barnett, Bakken and Woodford are representative of resource plays currently under exploitation in North America. All samples are from marine depositional environments, are thermally mature (T >445 °C) and have moderate to high organic matter content (2.9–11.6 wt% TOC). Their organic matter is dominated by solid bitumen, which contains intraparticle nano-porosity. Visual evaluation of organic nano-porosity (pore sizes < 100 nm) via SEM suggests that intraparticle organic nano-pores are most abundant in dry gas maturity samples and less abundant at lower wet gas/condensate and peak oil maturities. Samples were distributed to ILS participants in forty laboratories in the Americas, Europe, Africa and Australia; thirty-seven independent sets of results were received. Mean vitrinite reflectance (VR) values from all ILS participants range from 0.90 to 1.83% whereas mean solid bitumen reflectance (BR) values range from 0.85 to 2.04% (no outlying values excluded), confirming the thermally mature nature of all six samples. Using multiple statistical approaches to eliminate outlying values, we evaluated reproducibility limit R, the maximum difference between valid mean reflectance results obtained on the same sample by different operators in different laboratories using different instruments. Removal of outlying values where the individual signed multiple of standard deviation was >1.0 produced lowest R values, generally ≤0.5% (absolute reflectance), similar to a prior ILS for similar samples. Other traditional approaches to outlier removal (outside mean ± 1.5*interquartile range and outside F10 to F90 percentile range) also produced similar R values. Standard deviation values < 0.15*(VR or BR) reduce R and should be a requirement of dispersed organic matter reflectance analysis. After outlier removal, R values were 0.1%–0.2% for peak oil thermal maturity, about 0.3% for wet gas/condensate maturity and 0.4%–0.5% for dry gas maturity. That is, these R values represent the uncertainty (in absolute reflectance) that users of vitrinite and solid bitumen reflectance data should assign to any one individual reported mean reflectance value from a similar thermal maturity mudrock sample. R values of this magnitude indicate a need for further standardization of reflectance measurement of dispersed organic matter. Furthermore, these R values quantify realistic interlaboratory measurement dispersion for a difficult but critically important analytical technique necessary for thermal maturity determination in the source-rock reservoirs of unconventional petroleum systems., This research was funded by the USGS Energy Resources Program.

The Carboniferous – early Permian plant genus Lesleya is a characteristic component of “dryland floras” that occupied a wide range of moisture-stressed, well-drained environments in tropical regions of Euramerica. Fossil records of Lesleya are almost exclusively found in basinal lowlands. For example, occurrences in Early Pennsylvanian-age, seasonally dry, parautochthonous deposits in basinal lowlands of North America (e.g., Illinois Basin, USA) indicate that Lesleya lived in that region in low-altitude (lowland) paleoenvironments during dry climatic intervals. In this paper, we document the first occurrence of Lesleya during the Carboniferous on the Iberian Massif, in lower Gzhelian (Upper Pennsylvanian) strata of the Douro Carboniferous Basin, in northwestern Portugal. This newly discovered occurrence includes a new species, Lesleya iberiensis sp. nov., recognized on the basis of natural molds of leaves. The Portuguese Lesleya fossils are from upland intramontane deposits and occur between coal beds. Their fossil remains are preserved in mica-rich shales that were deposited between sandstone-dominated fluvial and shale-dominated lacustrine deposits, suggesting that this megaflora was deposited near freshwater bodies. These new data provide evidence that this megaflora grew in mountain riparian environments within the Variscan orogen, either in localized, well-drained areas or during drier climatic intervals in the Late Pennsylvanian.

During a study of fly ash from two pulverized fuel power plants (Bokaro and Chandrapura) burning coal from the Bokaro Coalfield in Jharkand state, India, glassy and vermicular mineral forms were found associated with the char. A combination of optical microscopy, XRD, SEM/EDS, and XRF analysis has shown that this morphotype, reported here for the first time, originated from kaolinite that expanded during heating inside the furnace chamber under relatively low combustion temperatures. The morphotype has an internal structure that resembles the fanning-out structure formed during vermicular kaolinite development.

The geochemical composition of unburned and burned/burning coal waste piles from past mining activities in El Bierzo Coalfield (NW Spain) was determined for the comprehensive characterization of the coals waste materials, for the identification of the mode of occurrence of environmental sensitive trace elements, and for the identification of geochemical changes induced by the thermal effects resulting from the combustion process. The methodologies used for the geochemical characterization of the coal and coal waste material included proximate analysis, ultimate analysis, inductively coupled plasma mass spectrometry for the determination of the inorganic composition of major and trace elements, and scanning electron microscopy with energy dispersive X-ray spectrometry. Considering the potentially hazardous trace elements, the results demonstrated that the unburned material are enriched in Pb, Sb, and Th, comparatively with the background of black shales (BBS). Considering the enrichment/depletion behavior of the elements in burned vs. unburned material, it was observed that Fe, K, Na, S, and Ti are enriched in burned material, while Ca, Mg, and P are depleted. The trace elements Nb, Re, Ta, Te, and W are enriched in burned waste material while Cd, Cu, Mn, Zn, and REE are depleted. Higher contents of oxygen and total sulfur, and lower content of carbon were determined in the burned/burning materials. The enrichment/depletion behavior of the elements is attributed to the self-burning process and to the changes caused by thermal effects. The enrichment of some elements may result from the elements' concentration due to the volatilization of other elements and organic matter consumption during the combustion process. The depletion of some elements may be associated with their volatilization during combustion. However, other reasons for this behavior, such as the elements mode of occurrence, weathering and/or leaching, should be considered. The investigation about the mode of occurrence of the worldwide potentially hazardous trace elements in coal wastes reveals that As, Cd, Pb, Sb and U are preferentially organically associated. However, As and Cd also presents some affinity with mineral mater. The elements Be, Co, Cr, Mn, Ni, Se and Th exhibit a significant association with mineral matter.

Plerospheres play a positive role in reducing particulate matter emissions, Br and U to the atmosphere, may assist in the synthesis of fly ash-based zeolites, and serve as a substrate to produce industrial grade multiwalled carbon nanotubes. Optical and electron microscopy and laser granulometry have been used to evaluate the nature and origin of char plerospheres in two pulverized fuel (p.f.) fly ashes and one fluidized bed fly ash derived from Bokaro and Jharia coals (Jharkhand, India). The influence of plerospheres on the particle size distribution of the fly ashes was also assessed, including the potential for fragmentation of the char shell during ultrasonic dispersion associated with laser granulometry. Char plerospheres were found to be common in one of the p.f. fly ashes (Chandrapura). Microscopic study shows that these are post-combustion morphotypes resulting from the infilling of the open-hollow-porous char particles by glassy morphotypes, and in this case should be classified as char pseudoplerospheres. Their formation is also related to the coal composition and the combustion conditions; the coal must contain vitrinite and low-reflectance semifusinite macerals that are able to produce open-hollow-porous char morphotypes, and the feed must be pulverized and heated in such a way that small glassy spheres are formed. Experiments using ultrasonic dispersion resulted in a shift from trimodal to bimodal particle size distribution for the Chandrapura ash, due to the fragmentation of the char plerospheres and release of the glassy spheres contained within them. It may therefore be expected that some particle size-related utilization-friendly properties of fly ashes containing char pseudoplerospheres could change during handling and with time.

Coal fires burning around the world over many years have been responsible for the loss of natural resources and also for negative environmental and human-health impacts. Study of self-burning coal wastes based on organic petrology, mineralogy and geochemistry allows the evaluation of factors responsible for the combustion process, and can also be used to assess the changes that are taking place in thermally affected materials. The main goal of this study is to characterize the materials from the Arroyo Galladas, Arroyo Mourin and Fabero coal waste piles, which resulted from coal mining in the El Bierzo Coalfield (NW Spain). Samples of coal, and of unburned and burned or burning coal waste material, were studied by optical microscopy and X-ray powder diffraction (XRD). The results demonstrate that some of the organic matter has preserved its characteristics, but other organic material shows signs of thermal alteration such as cracks, devolatilization vacuoles, dark reaction rims, plasticized edges, and increased or decreased vitrinite reflectance. The resistance of the unaltered organic matter to thermal effects is attributed to the coalification process previously undergone by these coals. The mineralogical composition of the samples indicates that newly formed minerals are present in the burned or burning material, including mullite, cristobalite, cordierite, hematite, jarosite, sanidine, anorthite, sulfur, pyrite, rozenite, coquimbite, tschermigite, boussingaultite and amorphous material. The formation of these minerals is attributed to combustion at maximum temperatures of at least 1100 °C in the Fabero coal waste pile and lower temperatures in the Arroyo Galladas coal waste pile, and to interaction of gases released by combustion with the solid particles, the waters and the atmosphere in and around the waste piles.

A Wenlock (Silurian) sedimentary continuous sequence was sampled in the Dornes region (Central Iberian Zone, Portugal) to characterize the organic matter type using different microscopic analyses (organic petrology and palynofacies). Total organic carbon (TOC) was also determined. Samples are part of Foz da Serta Formation and correspond to mudstone, punctually with sandstone, rich in organic matter (mean TOC value of 5.1%). Whole rock samples showed a dominance of non-granular graptolites (lath- and blocky-shape) and solid bitumen. Lath-shape graptolites display the characteristic segmented structure. In the blocky-shape graptolites, the fusellar layers of the graptolite wall are well marked and are an important distinctive feature. Foz da Serta graptolites are optically anisotropic as well as the solid bitumen. Non-granular graptolite's maximum reflectance varies from 1.43 to 3.94% and solid bitumen maximum reflectance oscillates between 1.09 and 2.22%. Vitrinite reflectance equivalent was calculated using Bertrand and Malo's equation (values between 1.97 and 3.72%) denoting a post-mature stage for the organic matter. No relation was established with confidence between graptolite maximum reflectance and solid bitumen maximum reflectance. The palynofacies study confirmed not only the presence of graptolite and solid bitumen but also amorphous material derived from graptolite. Under transmitted white light, graptolite features were not noticed. To improve the palynofacies characterization, reflected white light was used on slides, thus exposing distinctive graptolite features. The different lights and preparation types used allowed a better characterization of the organic matter present in Foz da Serta Formation samples, mainly the graptolites. The use of reflected white light, in the palynofacies study, proved to be extremely important in the description of the graptolite features.

The chemical, mineralogical, petrographic and textural characteristics of fly ashes from one fluidized-bed and two pulverized-fuel power stations in India, have been evaluated by a range of complementary methods, including optical and electron microscopies, laser granulometry, quantitative X-ray diffraction, X-ray fluorescence spectrometry and inductively-coupled plasma techniques. Mineralogical and geochemical analyses have also been carried out on the feed coals from the respective power stations, and the results were used to evaluate the changes produced during different combustion processes. Differences in particle size and shape for the ashes, and also differences in ash petrology and mineralogy, have been related to differences in the mineral matter of the feed coals, and to the milling characteristics and combustion temperatures in the different power plants. There is a potential of using these fly ashes as geoliner because of their fine texture and low permeability. Leaching tests have also been carried out on the fly ashes, as a basis for assessing the potential for adverse impacts on groundwater systems. The materials were blended with bentonite to decrease the permeability further. The major and trace element compositions of these ashes were determined. Most of the elements studied were leached in lower concentrations than averages for the same elements from European fly ashes. It is thus expected that these ashes will not provide significant source of additional contamination to permeating water if they are used with bentonite as geoliner material.

Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks .I n 2012e2013, an interlaboratory exercise was conducted to establish precision limits for the D7708 measurement

The study of the organic matter present in sedimentary rocks is fundamental for the characterization of the potential source rocks as well as to define the depositional paleoenvironments. Parameters of organic petrology and organic geochemistry, and their variations along sedimentary successions are essential tools to achieve these goals. Two borehole successions (Freixial-1 and Benfeito-1) from Arruda sub-basin (Lusitanian Basin), that comprise siliciclastic–carbonate deposits of Jurassic age, have been studied in order to characterize the organic matter and its vertical variability as well as its hydrocarbon potential. Palynofacies and geochemical data indicate both, marine (including zooclasts) and terrestrial organic matter where the phytoclasts predominated despite an important contribution of the amorphous organic matter (AOM). Different types of solid bitumen were observed. Most of the analyzed samples have total organic carbon content (TOC) lower than 1 wt.% and Hydrogen Index (HI) values lower than 100 mgHC/g TOC, revealing types III and IV kerogen. However, one set of samples exhibit TOC values higher than 1 wt.% and higher HI values depicting a type II kerogen. The biomarker data showed a dominance of n -alkanes with 15–30 carbon atoms having a unimodal distribution. Pristane/Phytane ratio varies between 0.04 and 1.84 indicating an alternation of oxic–anoxic conditions along the sequences. Typical terpane distributions are characterized by the presence of tricyclic and tetracyclic terpanes as well as pentacyclic terpanes (rare in carbonated samples from Freixial-1 borehole). The amount of 17α (H),22,29,30-trisnorhopane (Tm) usually exceeds the amount of 18α (H),22,29,30-trinorneohopane (Ts). The values of the ratio 22S/(22S + 22R) epimers of C32 homohopanes revealed that most samples reached equilibrium values. The 20S/(20S + 20R) and ββ/(αα + ββ) isomerization ratios in C29 sterane, calculated for the studied samples, range between 0.19–0.61 and 0.20–0.70, respectively, with several samples reaching the equilibrium values. The vitrinite reflectance values are higher than 0.5% indicating that the organic matter reached the oil generation window. According to the data obtained in this study, the Abadia, Montejunto, Cabacos and Brenha Formations can be considered potential source rocks of hydrocarbons (gas and/or oil) in this section of the Lusitanian Basin.

Geographical Information Systems (GIS) are often used to assess and monitor the environmental impacts caused by mining activities. The aim of this work was to develop a new application to produce dynamic maps for monitoring the temperature variations in a self-burning coal waste pile, under a GIS open source environment—GIS-ECOAL (freely available). The performance of the application was evaluated with distributed temperature measurements gathered in the S. Pedro da Cova (Portugal) coal waste pile. In order to obtain the temperature data, an optical fiber cable was disposed over the affected area of the pile, with 42 location stakes acting as precisely-located control points for the temperature measurement. A monthly data set from July (15 min of interval) was fed into the application and a video composed by several layouts with temperature measurements was created allowing for recognizing two main areas with higher temperatures. The field observations also allow the identification of these zones; however, the identification of an area with higher temperatures in the top of the studied area was only possible through the visualization of the images created by this application. The generated videos make possible the dynamic and continuous visualization of the combustion process in the monitored area., This work was supported by the project ECOAL-MGT-SOE3/P2/P714, Ecological Management of Coal Waste Piles in Combustion, SUDOE-Interreg IV B. Joana Ribeiro benefitted from a post-doctoral scholarship financed by FCT—Fundação para a Ciência e Tecnologia, Portugal, Ref: SFRH/BPD/76230/2011. The work of Sonia Martín-Lopez was supported by the Spanish Ministry of Science and Innovation through a “Ramón y Cajal” Contract. Miguel González Herráez acknowledges support of the European Research Council through Starting Grant U-FINE (Grant No. 307441). This work was also developed under the scope of the Institute of Earth Sciences, University of Porto. The author acknowledges the funding provided by the Institute of Earth Sciences (ICT), under contracts UID/GEO/04683/2013 with FCT (the Portuguese Science and Technology Foundation), and COMPETE POCI-01-0145-FEDER-007690. The authors would like to thank the DGT (Direção Geral do Território) and Instituto Português do Mar e da Atmosfera (IPMA) for the data provided., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

A new system for the microscopic classification of fly-ash components has been developed by the Fly-Ash Working Group, Commission III of the ICCP and is presented herein. The studied fly-ashes were obtained from the combustion of single coals of varied rank, coal blends, and coals blended with other fuels (biomass, petroleum coke), in different operating conditions and by means of different technologies. Microscopic images of the fly-ash samples were used to test the optical criteria proposed for classifying the fly-ash components. The classification system developed is based on a small number of microscopic criteria, subdivided into six independent levels or categories, three of which are directed at whole particle identification on the basis of nature, origin and type of fly-ash particle, while the other three levels are directed at the smaller section identification on the basis of character, structure and optical texture of unburned carbons. To classify the inorganic components of the fly-ash, the criterion proposed is composition in terms of metallic/non-metallic character. To establish the classification criteria the petrographers involved in the work performed three successive round robins. Evaluation of the results by using firstly descriptive statistics and then the criteria and parameters employed by the ICCP in their accreditation programs indicated that the classification of the fly-ash components was accurate and that there was only a minor bias. The main conclusion of this study was that the proposed criteria are valuable for identifying, and classifying fly-ash components and for describing the optical properties of fly-ash particles.

Palynomorphs undergo progressive darkening and loss of translucency as temperature increases over geological time periods. The use of oxidising agents that lighten highly mature palynomorphs enables their observation and documentation using transmitted light microscopes, but in certain cases, oxidation destroys part of or the entire organic residue. A new method was tested using palynological residues derived from Devonian and Carboniferous metasediments that allows the microscopic observation and documentation of highly mature palynomorphs without loss of specimens. In its simplest form, it uses non-oxidized, air-dried 20-μm-sieved palynological residues mounted on acrylic slides without the use of cover slips. Observation and documentation were performed routinely using reflected light petrographic microscopes. The resulting photomicrographs are scanning electron micrograph (SEM)-like in the sense that the observed objects are opaque. Depth-of-field issues can be easily overcome by editing the partially...

The Middle Jurassic to Cretaceous sedimentary record in the Lusitanian Basin (Portugal) reveals the presence of disseminated solid bitumen. The present work is focused on the petrographic characteristics of solid bitumen identified in the Freixial-1 and Benfeito-1 boreholes (Arruda sub-basin, Lusitanian Basin) that display different thermal maturities. Microscopy techniques (reflected and transmitted white light, incident blue light and SEM) and organic geochemistry analyses (total organic carbon, total sulfur and insoluble residue) were used to study these samples. From the results obtained by optical microscopy (fluorescence and reflectance) it was possible to distinguish three types of solid bitumen. They were labeled as solid bitumen A, present in all the samples, solid bitumen B and solid bitumen C, these ones observed in some of them. They correspond to allochthonous (migrated) bitumens. In blue incident light, some bitumen do not show fluorescence while others reveal fluorescence that range from yellow (solid bitumen B) to dark brown (solid bitumen A). All bitumens are optically isotropic. Bitumen reflectance varies between 0.70 and 2.60% R r , and the vitrinite reflectance ranges from 1.11 to 1.48% R r . Based on the % R r values, the solid bitumen identified in these samples are classified as impsonite (epi- and cata-) or pyrobitumen. No relation can be established with confidence for the reflectance of bitumens with the reflectance of vitrinite.