Main Seam Research Articles

Sphagnoid spores as tracers of environmental and climatic changes in peatland habitats of the early Eocene

AbstractPeat mosses have been an important part of the lignite forming vegetation in the early Eocene of the Helmstedt Lignite Mining District. Three genera of Sphagnum-type spores can be distinguished: Tripunctisporis, Distancoraesporis and Sphagnumsporites. The distribution of these sphagnoid spores is traced through seven lignite seams including most of the known hyperthermal events from the PETM to the EECO. In general, Sphagnum-type spores increase in importance from base to top in each seam as a result of acidification and nutrient depletion during peat accumulation. The proportion of Tripunctisporis increases from Main Seam to Seam 6. The lower three seams are characterized by assemblages typical for coastal plain swamp forests including tree stumps and charcoal in distinct layers and lenses. The upper seams, in which Tripunctisporis is dominant and woody material is rare, are thin-bedded with charcoal in numerous thin drapes on bedding planes. The palynomorph assemblages here indicate a low growing mainly herbaceous vegetation typical of ombrogenous bogs. The change from topogenous swamp forests to open ombrogenous bogs takes place along with the hyperthermals of the early Eocene from the PETM to the EECO. The change from a swamp forest to a shrub forest in the middle of the Main Seam coincides with the isotope excursion of the PETM. Similar changes in other seams independent of thermal events indicate that thermal events merely amplify changes in vegetation, which are primarily imposed by edaphic constraints. It is rather the rapid accumulation of hyperthermals during the EECO that exerts sufficient environmental stress to fundamentally alter the peat forming vegetation. Graphical abstract

Distance of Drill-Hole Determination based on Global Estimation Variance of Coal Resources Classification

Based on SNI 5015:2019, the estimation of coal resources is based on geological conditions, as well as the distance of information points for each geological condition and resource class. PT. AMNK is a coal mining company and has now started mining. The mines are divided into three blocks, north, middle, and south. Drilling activities have been carried out in the middle block, with 66 drilling points resulting in 4 main seams namely, H seam, I seam, J seam, and K seam. The average drill hole distance is 150 m. This type of coal deposit belongs to the moderate geological group characterized by the presence of a fault in the middle block. Further analysis of optimum drill hole distances is carried out as a basis for the estimation and classification of resources, which in 2024 will be used as an exploration target for the southern block. Analysis of the optimum drill hole distance based on the "relative error" value using the GEV (Global Estimation Variance) method and the size of the sill variogram. Based on the analysis of the K seam, the optimum borehole distances were 385 m, 750 m, and 1750 m, measured, indicated, and inferred categories, respectively.

The effects of iron-rich ultramafic pegmatite on the composition and mineralogy of the UG2 chromitite: a case study in the western Bushveld Complex, South Africa

Discordant iron-rich ultramafic pegmatites (IRUPs) intersect the UG2 chromitite at many places in the Bushveld Complex. The effects of IRUP interactions on the UG2 ore mineralogy and PGE grade are assessed at the Thaba mine, north-west Bushveld, based on a borehole profile through the UG2 layer and detailed analysis of mineral textures and compositional variations across the UG2-IRUP contacts using micro-XRF element mapping. The UG2-IRUP interaction operated at different scales and probably by different mechanisms. At the local scale (< 10 cm), a thin layer of Fe–Ti–Cr spinel and ilmenite formed on the IRUP side of the contact with UG2, whereas the UG2 chromitite developed grain coarsening, loss of interstitial silicates, and chemical gradients in Cr, Al, Fe, and Ti that extend a few centimeters from the contact into the seam. These local effects are attributed to the intrusion of IRUP melt into the solidified UG2 layer, followed by re-equilibration of the oxide minerals across the contact during cooling. On a larger scale, changes in the ore and gangue mineral assemblages in UG2 took place throughout the entire meter-thick main seam. Compared with regional UG2 compositions, chromite has higher TiO2 and lower Mg#, and there is an anomalously low abundance of interstitial plagioclase. The IRUP-affected UG2 shows relatively abundant secondary hydrous silicates, replacement of PGE sulfides by PGE alloys and PGE-As–Sb–Bi–Te–Pb phases, and formation of secondary Ni–Cu–Fe sulfides after pentlandite and chalcopyrite. These large-scale effects are attributed to hydrothermal fluids derived from IRUP melts. The IRUP bodies at the Thaba mine caused redistribution of PGE within the UG2 layer but did not significantly reduce the overall grade. However, significant changes in the ore mineral assemblage and an increased abundance of secondary silicates can reduce the efficiency of PGE recovery.

Early Eocene carbon isotope excursions in a lignite-bearing succession at the southern edge of the proto-North Sea (Schöningen, Germany)

Abstract. Situated at the southern edge of the proto-North Sea, the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany, is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data for bulk organic matter (δ13CTOC), total organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation in combination with a new robust age model, which is based on eustatic sea level changes, biostratigraphy, and a correlation with existing radiometric ages. Based on the δ13CTOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ13CTOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ13CTOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least four minor CIEs with a maximum negative shift of −1.3 ‰ in δ13CTOC in the upper part of the studied section are characteristic of the Early Eocene Climatic Optimum (EECO). Palynological analysis across the Main Seam proved that shifts in δ13CTOC values are correlated with changes in the peat-forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to angiosperm-dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ13CTOC values shortly after the onset of the CIE, which is recognized here as a common feature of terrestrial and marginal marine PETM records worldwide and may reflect a stepwise injection of carbon into the atmosphere.

Coal cleaning through removal of phosphorus mineral from morupule main seam coal

ABSTRACT Phosphorus is critical for the strength of metals; however, in excess it makes the metal product fragile. This leads to quality complaints and financial losses. Phosphorus is finely disseminated in coal and forms part of the coal structure. Despite the use of a coal facility at Morupule, the final product surpasses the maximum limit of 0.02% phosphorus. Reduction of the phosphorus by convectional coal cleaning processes is a challenge due to the mineral associations with the coal structure. Selective mining is the current implemented option at Morupule to attain the low phosphorus production but it is costly and time-consuming. Hence, the aim of the research to investigate coal leaching as a primary method for phosphorus reduction. Hydrochloric acid at 1 Mol concentration was used for 4 hours at room temperature. Sixty-four percent phosphorus removal was achieved resulting in 0.012% residual phosphorus. To improve the rate of reaction, microwave pretreatment was conducted to further reduce the amount of phosphorus in the coal. The effect of phosphorus reduction using 1000 W single-mode cavity was compared to that of the multimode cavity. The optimum processing parameters were 2 minutes and 3 hours leaching time to yield a residual phosphorus of 0.008%.

Longwall top coal caving design for thick coal seam in very poor strength surrounding strata

Alpu lignite field is an important coal deposit with nearly 2 billion tons of coal resources located in the middle of Turkey. The mine deposit consists of three main seams. The thickness of two of them vary from 4 to 30 m. The surrounding rock mass is very poor in terms of strength. The high clay content and weak rock mass make mechanized mining difficult. In this research, applicability of the longwall top coal caving method was investigated. The very weak strength behavior of the coal and the surrounding strata increases the importance of research in the mine site in terms of ground control. The aim is to design the mechanized longwall mine based on ground control principles. First of all, classification of the roof, coal, inter-burden, and floor strata were classified based on geotechnical aspects. Then, cavability index, shield, and floor bearing capacity were investigated. Different methods were applied to understand the limitations of a mechanized system that is very critical due to the very low strength strata. According to the main results, roof strata was classified as immediately caving while mining height was calculated as 5–6 m. Finally, the relations among geotechnical characterizations of roof and floor strata, cutting and caving heights, and required shield capacity were presented based on analytical and numerical applications. The proposed approach can be used as a ground control method for the applicability as well as the limitations of mechanized longwall mining design in weak strata conditions.

Estimation of Overburden and Estimation of Mineable of Coal Reserved on Pit at Area B III Warute South at Coal Contract of Work (CCOW) Pt. Antang Gunung Meratus Sungai Raya Sub-District, Hulu Sungai Selatan District East Kalimantan

In accordance with technological advances in the field of mining, nowadays more and more computerized -based programs that can facilitate the work of modeling and calculation of reserves and mining of various kinds of designs. These programs were created to support the work on the basis of the work that does not change the basic concept and philosophy of the calculation. Detail research was performed on pit at area B III warute south At Coal Contract Of Work (CCoW) PT. Antang Gunung Meratus Sungai Raya Sub-District, Hulu Sungai Selatan District East Kalimantan Province. Estimation of overburden and mineable coal reserves through of redesign of mining pit was conducted using the cross section method with computerized software system autocad 2007 and minescape 4.1.1.9Estimation of overburden and Mineable coal reserved calculation performed on the main seam M4. The M4 seam shows varying thickness of coal, with a wavy layer structure and split. The slope of coal in the study area is generally relatively steep, which is in the range 38° - 42° with the strike direction of the N200°E - N210°E.Estimation of overburden and mineable coal reserves using the cross section method are: overburden volume is 1339886,283 BCM and mineable coal reserves is 459678, 6117 MT so that the value of Stripping Ratio obtained was 2.97

ПОШИРЕННЯ РТУТІ У ШАРАХ ВУГІЛЛЯ (НА ПРИКЛАДІ КРАСНОАРМІЙСЬКОГО ГЕОЛОГО-ПРОМИСЛОВОГО РАЙОНУ ДОНБАСУ)

Purpose. Analysis of the distribution of mercury concentrations in the whole district; identification of links between mercury content and other toxic and potentially toxic elements, petrographic composition of coal and its main technological parameters. Methodology. The methods of mathematical statistics with the construction of histograms of distribution and dendrograms of clustering of coal seams of the region by Hg concentrations are also used in the work. Results. Peculiarities of distribution and the nature of mercury distribution in 56 coal seams, which belong to the suites С14, С21, С22, С23, С25, С26, and С27 of the lower and middle divisions of the coal period of the Krasnoarmeysk geologicalindustrial area, have been determined. Simple and cumulative histograms are constructed and analyzed. The calculations of the weighted average concentrations in the coal of the main layers and suites were performed, the composition of the typomorphic geochemical association of mercury with other toxic and potentially toxic elements in the coal of the region is clarified. The main factors influencing the mercury content in the nearest stratigraphic section of coal seams in the process of coal accumulation and epigenetic transformations of the coal seam were significantly varied. The average value of mercury content in coal of the main working seams of the area is significantly below the maximum allowable concentration in coal. In the district as a whole, there is no significant connection between mercury concentrations and ash content and sulfur content of total coal, at the same time there is an increase in mercury content with increasing degree of coal carbonization. Scientific novelty. The nature of the distribution and the main statistical indicators of mercury concentrations in the main coal seams and suites of the Krasnoarmeysky geological-industrial region of Donbass were established. A typomorphic geochemical association of mercury with other toxic and potentially toxic elements in the coal seams of the district has been established. Practical significance. The practical significance of the obtained results is to identify the absence of a significant relationship between mercury concentrations and ash content and sulfur content of total coal, as well as to calculate the regression equations between the elements included in the geochemical association with mercury. Key words: mercury, mine, coal height, coal ash content, depth, sulfur content, regression equation, correlation coefficient.

ANALYSIS OF THE DISTRIBUTION OF CHROME AND MERCURY IN THE MAIN COALS OF THE RED ARMY GEOLOGICAL AND INDUSTRIAL AREA

Increasing requirements for environmental protection in the coal mining industry in Ukraine stipulates the need for new scientifically grounded methods for forecasting the content of toxic and potentially toxic elements in rock mass, mining waste and coal enrichment which is mined by mines, as well as the environmental impact by enterprises of heat power industry. For this purpose it is necessary to have data about concentration, character and peculiarities of the distribution of toxic and potentially toxic elements, including mercury and chromium in the coal seams. The studies covered all territory of one of the most studied geological and industrial areas of the Donbas - Krasnoarmiiskyi. In the article, peculiarities of the distribution of mercury and chromium are considered and character of their spreading in the coal seams are established, weighted average concentrations in the coal of the main seams and suite are calculated. Hystograms of distribution of mercury and chromium content in coal seams, as well as dendrograms of clustering results by weighted centroid method of coal seams by their content, have been constructed and analyzed. The accumulation of mercury and chromium in the coal seams of the district is polygenic and polychronic. The main form of finding these elements in the coal seams is sorbed (on clay minerals and fusenized microcomponents), and for mercury also sulfide (in epigenetic pyrites).

Contribution to Gas Production from Minor Coal Seams and Adjacent Shales: Numerical Modelling Results for the Mannville Coal Measures, South Central Alberta

The contribution to production of the gas stored within the coal and shale beds adjacent to the main coal seam in the Mannville Group, in which a lateral is drilled, was investigated through a series of numerical simulations. The results indicate that the added gas from the minor coal seams, with interbedded shales with no gas, results in 1.4 times (×) more produced gas and 3.0× more produced water after 25 years of production than when only the main Mannville coal seam is considered. Including gas in the shales results in 1.7× more produced gas and 2.5× more produced water after 25 years of production than when only the main coal seam is considered. The produced gas recovered from the shales exceeds the produced gas recovered from the coals after ~8.5 years, resulting in 2.1× more produced shale gas than coal gas after 25 years of production. Over half (56%) of the produced coal gas after 25 years of production is recovered from the main coal seam while a quarter (22%) is recovered from the L1 seam, which is the thickest and nearest minor coal seam to the horizontal wellbore located in the main seam. The results from the numerical simulations provide insights that are not intuitive or otherwise predictable in developing complex reservoirs. Although the results are specifically for the Mannville producing fairway, undoubtedly the production from minor coal seams and interbedded gas shales should be considered in other producing and potential coal gas reservoirs to identify higher producible reserves and optimize drilling and completions strategies.

Distribution and Mobility Potential of Trace Elements in the Main Seam of the Most Coal Basin

The Most Basin represents a coal basin with a long mining history in the Czech Republic. The majority of palaeo-environmental and geochemical studies have been focused on the upper part of the coal-bearing Most Formation where the coal is generally enriched in As, Cr, Ni, Cu and Zn. This study evaluated the distribution of V, Cr, Ni, Cu, Zn, Pb, Se, As, and Mn from the lower part. Regarding to the transport of inorganic elements into environment, the evaluation of mobility potential was also conducted.The total of 51 samples were collected from the Lower Bench in the Holešice Member. The chemical analyses were performed together with optical microscopy. The X-ray spectroscopy and ICP-MS were used to detect trace element contents in the study set of samples. 4 samples were subjected to the Sequential Extraction Procedure. The prepared leachates were analysed using the ICP-MS method.In total, 13 elements were screened in samples within the study profile. The mode of occurrence is the key factor for identifying a potential source of the trace elements. All evaluated trace elements (V, Cr, Ni, Cu, Zn, Pb, Se, As and Mn) leached most in the oxidisable fraction. On the other hand, As, Mn, Ni, Zn and Cd leached in more mobile fractions, e.g. reducible and acid.

Litho- and chemostratigraphy of the Flatreef PGE deposit, northern Bushveld Complex

The Flatreef is a world-class platinum-group element (PGE) deposit recently discovered down-dip from existing mining and exploration operations on the northern limb of the Bushveld Complex. Current indicated resources stand at 42 Moz PGE (346 Mt with 3.8 g/t Pt+Pd+Rh+Au, 0.32% Ni and 0.16% Cu) which, in the case of Pt, is equivalent to ~ 10 years global annual production, making it one of the largest PGE deposits on earth. The grade and thickness of the Flatreef mineralised interval is highly unusual, with some drill core intersections containing up to 4.5 g/t Pt+Pd+Rh+Au over 90 m in drill core. Here, we document the down-dip and along-strike litho- and chemostratigraphy of the Flatreef and its footwall and hanging wall rocks, based on a diamond drill core database totalling > 720 km. At the base of the sequence intersected in the drill cores are up to 700-m-thick sills of ultramafic rocks (dunite, harzburgite, pyroxenite) emplaced into pelitic, dolomitic, and locally quartzitic and evaporitic rocks belonging to the Duitschland Formation of the Transvaal Supergroup. Next is an approximately 100–200-m sequence of low-grade-sulphide-mineralised, layered mafic-ultramafic rocks containing abundant sedimentary xenoliths and, in places, several chromite seams or stringers. This is overlain by a ~ 100-m-thick sequence of well-mineralised mafic-ultramafic rocks (the Flatreef sensu strictu), overlain by a laterally persistent mottled anorthosite layer at the base of > 1 km of homogenous Main Zone gabbronorite. Based on stratigraphic, lithological and compositional analogies to the layered rocks in the eastern and western Bushveld Complex, we correlate the Flatreef and its chromite bearing footwall rocks with the Upper Critical Zone, notably the interval between the UG2 chromitite and the Bastard Reef as found elsewhere in the Bushveld Complex. This includes recognition of a Merensky Reef correlative. The ultramafic rocks below the main chromitite seam (UG2 correlative) in the Flatreef footwall are correlated with the Lower Critical and Lower zones. However, compared to the western and eastern Bushveld limbs, the studied sequence is strongly enriched in sulphide and PGE, many of the rocks show elevated CaO, K2O, Rb and Zr contents, and lateral continuity of layers between drill cores is less pronounced than elsewhere in the Bushveld, whereas ultramafic units are locally considerably thickened. These compositional and lithological traits are interpreted to result from a range of processes which include contamination with calcsilicate and hornfels, intrusion of granitic magmas, and the influence of multiple structural events such as pre- to syn-emplacement regional-scale open folding and growth faults. Evidence for the existence of potholes also exists. In the shallow, up-dip portions of the project area, the entire magmatic sequence below the Main Zone becomes increasingly contaminated to the extent that individual units are somewhat more difficult to correlate between drill cores. This package represents the Platreef as exposed in outcrop and shallow bore holes across much of the northern limb of the Bushveld Complex. The new data presented here thus indicate that the Platreef is a relatively more contaminated up-dip extension of parts of the Critical and Lower zones.

Application of nuclear magnetic resonance (NMR) technology to study the space distribution features of underground brine from playa lakes:A case study of Kunteyi Playa Lake

昆特依干盐湖位于柴达木盆地西北部，为特大型综合盐类矿床.大盐滩是昆特依干盐湖内最大的盐滩，地下赋存有一定量的卤水矿床，但该矿床的水文地质条件差，主要卤水矿层含水性弱，开采难度大.核磁共振找水方法作为当今世界上唯一的直接找水地球物理新方法，具有高分辨力、高效率、信息量丰富和解的唯一性等优点，本文运用该方法对昆特依干盐滩地区地下卤水空间分布特征进行研究，通过对核磁共振数据进行处理与反演，结合已有的地质与钻井资料，对测点进行综合地质地球物理解释，获得以下认识：1）大盐滩0~130 m深度范围内，共存在3个卤水含水层，主要呈扁平状或漏斗状、近似层状展布，W₁为晶间潜卤水层，渗透系数较大，颗粒较粗，单位体积含水量为0.4%~2.7%，W₂和W₃为晶间承压卤水层，渗透系数较小，颗粒较粗，单位体积含水量分别为0.2%~1.1%和0.1%~0.8%；2）大盐滩地区存在两个卤水富集区，分别为研究区西南部沉积盆地中心的Ⅰ号富卤区和盆地东北部的Ⅱ号富卤区；3）根据区域内卤水富集分布以及构造情况，划定大盐滩向斜沉积中心、大盐滩北侧F1~F8及遥F6断裂发育区和冷湖构造带为区域内主要的找矿找水远景区；4） GMR核磁共振系统在干盐滩地区理论探测深度为130 m，该系统不仅可以有效地探测自由水，而且可以依据束缚水的分布解译地下各类含水盐类矿物和含水黏土矿物的存在与分布.;Kunteyi Playa Lake, located in the northwest of Qaidam Basin, is an extremely large comprehensive salt deposit. The Great Salt Beach is the largest salt beach in the Kunteyi Playa Lake with underground brine deposit, poor hydrogeological conditions, and extremely low water content in the main seam, so it is difficult to exploit. Nuclear Magnetic Resonance (NMR) is a effective geophysical method currently used to detect groundwater directly. Comparing with the traditional geophysical methods, the NMR method is of higher resolution, more efficiency, more information and unique interpretation for hydrogeological investigations. In this paper, NMR sounding is used to study the space distribution characteristics of the underground brine. The NMR data were processed with the inversion, combined with geological and drilling data, and integrated with geological and geophysical interpretation for each measuring point. We find that in Kunteyi Playa Lake there are three brine aquifers exists from 0 to 130 m below the surface. The distribution of three brine aquifers is like funnel-shaped or approximate layer. The W₁ is latent brine formations, large permeability and coarse grain, with per unit volume of water of 0.4%-2.7%. The W₂ and W₃ are pressurized brine, low permeability and coarse grain, with per unit volume of water of 0.2%-1.1% and 0.1%-0.8% respectively. There existed two brine enrichment regions in the study area, the southwest centre of the exploration basin and the northeast basin. According to the distribution of brine and the structure in this area, we delimitate prospecting area of underground brine, the depositional centre of Great Salt Beach Synclinal, fault F1 to F8 and remote sensing fault F6 development areas in the north of the Great Salt Beach, cold-lake Structural belt. In dry salt lake area, the reliable detection depth of GMR system is 130 m. GMR systems can detect not only free water effectively, but also distribution of bound water to interpret the distribution rule of water-bearing salt minerals and aquiferous clay minerals.

The geometry, distribution and development of sand bodies in the Miocene-age Frimmersdorf Seam (Garzweiler open-cast mine), Lower Rhine Basin, Germany: implications for seam exploitation

AbstractThe Cenozoic-age Lower Rhine Basin is located in the NW part of the European Cenozoic Rift System. In Miocene times, a combination of warm climatic conditions and basin subsidence resulted in the deposition of up to 100m of lignite (i.e. Main Seam of the Ville Formation). The Main Seam can be subdivided into the Morken, Frimmersdorf and Garzweiler seams, separated by two intercalated transgressive sand units, namely the Frimmersdorf and Neurath sands, deposited in a shallow-marine, tide-dominated environment. The lignite seams of the Ville Formation are currently worked by RWE Power AG, in the Garzweiler II open-cast mine. In the Frimmersdorf Seam (between the Frimmersdorf Sand and the Neurath Sand), the presence of small-scale sand bodies, together with their variable dimensions, affects the industrial exploitation of the seam. Moreover, their irregular distribution complicates their precise and early recognition. Indeed, so-called barren lignite (≥ 17% of sand) and completely clean units can occur within a few metres of each other. Initial classification of these highly variable sand bodies suggests a variety of both pre- and post-depositional causal mechanisms, providing evidence of an extremely complex depositional and post-depositional system. Syn-depositional sand bodies were deposited in a swamp area that was located in the fluvial-dominated sub-environment of an extended tidal estuary. The post-depositional formation of sand bodies is related to the intrusion of fluidized sands from the underlying Frimmersdorf Sand. These sand injectites within the Frimmersdorf Seam are considered to be linked to seismic activity within the Lower Rhine Basin.

A regional review and new insights into SE Asian Cenozoic coal-bearing sediments: Why does Indonesia have such extensive coal deposits?

A regional review and new insights into SE Asian Cenozoic coal-bearing sediments: Why does Indonesia have such extensive coal deposits?

The origin of lithotype cycles in Oligo-Miocene brown coals from Australia and Germany

Brown coal colour lithotype cycles range from 10 to 30m thick in Oligo-Miocene coals of the Latrobe Valley, Gippsland Basin, Australia. Similar colour lithotype cycles occur in the Lusatia German Miocene brown coals. In both the Latrobe Valley and Germany, the cycles often display well-developed colour-lightening-upward trends as defined by new colourimetry measurement. The typical lithotype cycle boundary is abrupt between light below and dark lithotype above. Geological, geochemical, palynological and macrofossil evidence is consistent with a relative drying (terrestrialisation) upward depositional model for each cycle, and the overlying dark lithotype represents renewed peat accretion. The dark lithotype may include charcoal near the cycle base, explained by the fire-prone and highly flammable nature of the herbaceous/reed wetlands. In both the German and Australian coals, wetter (darker) lithotypes are characterized by a gymnosperm paleoflora, while drier (lighter) lithotypes are characterized by angiosperms.In the German (Rhenish) Miocene brown coal exposed in large open cut mines at Garzweiler and Hambach, a 1.0m spaced sampling and colourimetry measurement program shows lightening-upwards cycles for the Morken seam, Frimmersdorf-A seam, Frimmersdorf-B seam and for the Garzweiler-II seam. At Hambach where the 60m thick ‘Main Seam’ includes amalgamations of Frimmersdorf-A, Frimmersdorf-B and Garzweiler-I, II & III seams, the lightening-upwards trends, provides a means of stratigraphic subdivision.The palaeogeographic setting for Latrobe Valley and German brown coals is similar – in Latrobe Valley the seams split and thin to the east into marine facies. In the Rhenish and Lusatia brown coals they also split and thin to the north into marine facies. The two Rhenish mines at Hambach and Garzweiler respectively typify end members of this palaeogeography – the Hambach mine is located in a distal location where sulphur content is negligible; the Garzweiler mine is located in a proximal location to the marine boundary where sulphur content is higher. The colourimetry and facies succession suggest German brown coal deposition followed a similar cyclic depositional succession to the Latrobe Valley, and that this succession may be fundamental in all thick coal seams.

Modelling of a coal seam of the deposit Đurđevik (BiH) by means of 2D reflection seismic imaging

A low cost 2D reflection seismic survey was used to map the continuity of the main seams as well as the numerous faults at the Đurđevik sub-bituminous coal deposit (BiH). A 24-channel seismic data acquisition system was available for this survey. The natural high reflectivity of the coal seams and a favourable geometry of seismic profiles enabled the identification and correlation of major faults across the area. Rugged terrain presented challenges to both data acquisition and processing. Stacks of acceptable quality were obtained only after the application of surface consistent statics and careful application of multi-channel filtering. A set of recorded 2D lines was interpreted in a 3D environment. Inferred structural elements disrupting the seam continuity were identified and were in agreement with available drilling results and mine workings. The result of this work was used to reduce mining hazards and also to help optimise mine planning.

Compositional variation and palaeoenvironment of the volcanolithic Fort Cooper Coal Measures, Bowen Basin, Australia

An integrated analysis of megascopic lithotype, microscopic maceral and mineral composition, stable carbon isotope and interburden sedimentology from a single well was used to interpret the response of the Late Permian Fort Cooper Coal Measures (FCCM) to regional and global environmental influences. The FCCM are differentiated from underlying, relatively high vitrinite Moranbah Coal Measures, and overlying higher inertinite Rangal Coal Measures in the Bowen Basin by their intercalation with abundant tuff and siliciclastic partings and interbeds. Besides this, there is little described about the variation in the organic composition of the FCCM and its causes. The FCCM can be subdivided into a lower aggradational Fair Hill Formation, transgressed by the shallow marine-derived Black Alley Shale that interfinger with/is overlain by the progradational Middle Main Seams and Burngrove Formation coal measures. The coals are dominantly dull with minor bright bands that are more abundant in the Burngrove Formation representing a change in plant composition. The maceral analysis shows that the coals in the Fair Hill Formation and Middle Main Seams are vitrinite-rich (80–90% mmf) albeit with high mineral matter suggesting the formation of precursory peat under rising water levels and with high sediment (tuff) influx and preservation. The coals in the Burngrove Formation have an increased inertinite content (30% mmf) but are also high in mineral matter suggesting a shift to increased decomposition arising from a fluctuating water table, possibly increased aridity and/or microbial activity. Tuffs occur throughout, and although their frequency is higher in the lower Fair Hill Formation, the preservation of thicker tuffs in the upper Burngrove Formation indicates increased intensity of volcanism that could have modified the environment. Variation in carbon isotope compositions show a parabolic trend, from around −24.1‰ in the Fair Hill Formation to more variable values in the Middle Main Seams with an overall 13C-enrichment upwards in the Burngrove Formation, prior to the δ13C values becoming negative (depleted between −1 to −4% from the average −24.1‰) in the top seams and into the overlying Rangal Coal Measures. The 13C-depletion trend in the upper part of the section is unexpected in view of corresponding increase in inertinite content of the coals indicating that the δ13C values/plant composition and inertinite content are decoupled, unless the inertinite origin is from intense microbial decay. Similar stable carbon isotope depletion trends have been observed elsewhere in an equivalent stratigraphic interval of the Bowen Basin suggesting that the carbon isotope values are responding to global conditions that cause negative excursions in carbon isotopes before the P-T boundary. Overall, the basin was continuously subsiding and peats accumulated with constant interruptions from excessive sedimentation and volcanic eruptions. The low proportion of visible thick bright bands coupled with high telovitrinite (mmf) content suggests a marsh to fen environment, with an open canopy and ponding able to preserve volcanic ash falls.

The quality of coal and hydrogeological characteristics in deposit 'Delici and Peljave-Tobut' near Ugljevik

Geological study of 'Delici and Peljave - Tobut' coal deposit, located in north-eastern part of the Republic of Srpska (B&H), has given a new insight into geological structure of coal-bearing series and quality of coal. Coal-bearing series was formed in a lower Miocene lake and has complex geological-tectonic structure and litho-facial diversity. Two coal seam are identified within this series - the older one, so-called the Main coal seam (developed throughout the deposit; with major coal reserves) and the younger one - Upper coal seam, which is of a restricted areal extent. Coal from this deposit has a variable ash content -34.91% on average in the Main seam and 44.58% on average in the Upper seam. This coal has an average sulfur content of 3.73% in the Main seam and 2.73% in the Upper seam. An average moisture content is 19.07% in the Main seam and 18.26% in the Upper seam. An average lower heating value is 111.671 kJ/kg for the Main seam and 7.952 kJ/kg for the Upper seam. Petrographic study of coal have shown that the coal of this deposit has high content of huminite, increased content of liptinite, low content of inertinite and increased content of mineral matter. Densinite is a dominant maceral of huminite group, while ulminite is less abundant. The content of other macerals of this group is low.

Rangal Supermodel 2015

More than 6,000 boreholes were compiled to develop a consistent regional scale stratigraphic framework for the Permian Rangal, Baralaba and Bandana coal measures (CMs) within the Bowen Basin. Coal beds and tuff horizons were used as stratigraphic markers, supported by chemostratigraphy and age dating. Results corroborate the general subdivisions of these different coal measures relative to basin location, but increase resolution on migrating depocentres in response to foreland loading and subsidence on coal thickness and splitting patterns. In the north, the Rangal CMs comprise two main seams, correlated as Leichhardt and Vermont. The Yarrabee Tuff is consistently present and splits the Vermont seam. The main Leichhardt seam exhibits relatively simple offset stacking relationships with the underlying Vermont and overlying Phillips seams. In the southwest, the Bandana CMs comprise two to three significant seams—the Aries-Castor, Pollux (Leichhardt equivalent) and Orion—along with the Pisces containing the Yarrabee Tuff. Seams exhibit complex Z splitting and vertical interburden stacking. Locally super-thick seams (crabs) form from convergence of thinner split seams in areas of relative stability over basement highs. In the Taroom Trough, the Baralaba CMs show the greatest response to loading, as seams thin and split along the eastern margin. The variability in the splitting patterns, coupled with the coal measures total thickness, corroborate the extension of the final basin depocentre northward, which was not preserved.