EARLY STAGES OF LIGNITE FORMATION IN PTOLEMAIS BASIN: A COAL-PETROGRAPHIC APPROACH

With the present study it is intended to assess the depositional palaeoenvironment of the lower part of the Lignite-bearing Sequence in the Ptolemais Basin, and more specifically in the areas of Notio-Field and Tomeas-6 open pits. The sediments under study represent the seam between the Volcanic Tephra Layer and the Basal Marl, which constitute the roof and the floor, respectively. Coal-petrographic results showed that Huminite is the main macerai group (84-96%), while macérais from Liptinite and Inertinite groups display low values (<10%). In bulk lignite samples the main mineral phases are quartz, calcite, clay minerals and feldspars, while in the ashes the main phases are quartz, anhydrite and lime. The palaeoenvironment of the lignite formation was reconstructed using the lithological, coalpetrographic and mineralogical data, as well as coal-facies diagrammes. In Notio-Field Mine, at the early stages of lignite formation the conditions used to be limnotelmatic, while in Tomeas-6 Mine they were telmatic. Upwards the conditions turned to more telmatic in both mine areas. The vegetation was mainly herbaceous with some arboreal elements occurring mostly in Tomeas-6 area. The water influx was generally intense resulting in enhanced inorganic inpu

Vertical zonation of testate amoebae in the Elatia Mires, northern Greece : palaeoecological evidence for a wetland response to recent climate change or autogenic processes?

The Elatia Mires of northern Greece are unique ecosystems of high conservation value. The mires are climatically marginal and may be sensitive to changing hydroclimate, while northern Greece has experienced a significant increase in aridity since the late twentieth century. To investigate the impact of recent climatic change on the hydrology of the mires, the palaeoecological record was investigated from three near-surface monoliths extracted from two sites. Testate amoebae were analysed as sensitive indicators of hydrology. Results were interpreted using transfer function models to provide quantitative reconstructions of changing water table depth and pH. AMS radiocarbon dates and 210Pb suggest the peats were deposited within the last c. 50 years, but do not allow a secure chronology to be established. Results from all three profiles show a distinct shift towards a more xerophilic community particularly noted by increases in Euglypha species. Transfer function results infer a distinct lowering of water tables in this period. A hydrological response to recent climate change is a tenable hypothesis to explain this change; however other possible explanations include selective test decay, vertical zonation of living amoebae, ombrotrophication and local hydrological change. It is suggested that a peatland response to climatic change is the most probable hypothesis, showing the sensitivity of marginal peatlands to recent climatic change

Development of a petrographic classification of fly-ash components from coal combustion and co-combustion. (An ICCP Classification System, Fly-Ash Working Group – Commission III.)

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

Geological factors influencing the concentration of trace elements in the Philippi peatland, eastern Macedonia, Greece

17 páginas, 4 figuras, 5 tablas.Six peat samples obtained from the Holocene and the Weichselian of the Philippi peat deposit, eastern Macedonia, Greece, were analyzed for 48 trace elements by Inductively Coupled Plasma–Mass Spectrometry (ICP–MS). The ash contents of these samples were also determined. Most of the trace elements are associated with the minerals in the peat, while Ge, Mo, Pb, Se, Ta, Tl, U, and W display a greater affinity with the organic matter. Compared with crustal averages (Clarke concentrations), the Philippi peat is enriched in some elements (Ag, As, Au, Cd, Mo, Se, Te, U, and W) because of the respective mineralizations in the area. The Philippi peat is also enriched in Cr, Cu, Mo, Pb, Sc, Sn, T, V, Y, and Zn in comparison with typical fen peats, as well as in As, Cr, Mo, Se, and U in comparison with typical coals. Climatic and hydrogeological conditions strongly influenced the peat-forming environment resulting in a differentiation between Holocene and Weichselian peat. Generally, the Holocene peat contains lower concentrations of trace elements in the northern and southern part of the fen, than the Weichselian one. The opposite trend is observed in the fen area close to the western basin margins.Peer reviewe

Testing reproducibility of vitrinite and solid bitumen reflectance measurements in North American unconventional source-rock reservoir petroleum systems

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 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