Oil Shale Beds Research Articles

Palaeoenvironmental and palaeoecological reconstructions based on oxygen, carbon and sulfur isotopes of Early Permian shark spines from the French Massif central

The palaeoecology of the Xenacanthiformes (Chondrichthyes) is still a matter of discussion. Historically considered as freshwater organisms, hypotheses of euryhaline ecology including migratory behaviour were recently proposed based on the histology of their dorsal spines. However, recent studies still argued for a full freshwater ecology based on the geochemical compositions of their teeth. Their ecology is particularly interesting to investigate for those coming from the environmentally ambiguous Early Permian intra-mountainous localities of Buxières-les-Mines (Bourbon-l'Archambault Basin, Allier) and the Muse oil-shale bed (OSB) (Autun Basin, Saône-et-Loire) from the French Massif central. These two localities were interpreted as freshwater settings but doubts on marine influences exist. To assess their palaeoenvironment and the palaeoecology settings based on xenacanthiforms occurrences, we have analysed the stable isotope compositions (δ18O, δ13C and δ34S) of the bioapatite of their vertebrate faunas. From these stable isotope compositions, we interpret that Buxières-les-Mines was a large and deep freshwater lake, equivalent to the modern Indonesian Lake Matano, whereas the Muse OSB is interpreted as a shallow tropical lake with drying events, equivalent to the Lake Punta Laguna in Amazonia or the Lake Tanganyika in Africa. The oxygen isotope compositions of the xenacanth dorsal spines of Buxières-les-Mines are relatively constant from the apex to the base. Such uniform isotopic compositions recorded during the life of xenacanths support either their sedentary lifestyle or stenohalinity. The apparent ability of small xenacanthiforms to endure drying up, as shown by the variations in isotope composition of the Muse OSB specimens, could explain their resilience during the Early Permian whereas Carboniferous xenacanthiforms occurring in large lake and river systems almost disappeared.

A new Triodus shark species (Xenacanthidae, Xenacanthiformes) from the lowermost Permian of France and its paleobiogeographic implications

ABSTRACT The Xenacanthiformes from Central and Eastern European deposits have been extensively studied, but the systematics of the species from the French Carboniferous–Permian Autun Basin (Saône-et-Loire) remains debated. Numerous xenacanthiform remains are still identified under the doubtful genus ‘Expleuracanthus’, and many of them consist of isolated dorsal spines which are difficult to identify. Numerous well-preserved specimens are still undescribed and the diversity of the xenacanthiform fauna from the Autun Basin is poorly understood. For example, specimens of the genus Triodus from the Muse oil-shale bed (OSB) of the Autun Basin have no specific attribution, whereas this genus is widely distributed across European Carboniferous–Permian basins. In this study, we describe new specimens of Triodus from the lowermost Permian of the Muse OSB. They allow the erection of a new species, Triodus aeduorum sp. nov., and discussion of the validity of several species from the same locality: ‘Expleuracanthus’ frossardi is considered as a nomen dubium and other Triodus specimens need for the time being to be left in open nomenclature as Triodus sp. These results highlight the endemism of the Triodus species in each European Carboniferous–Permian basin and raise the question of how they migrated from one to another.

Mineralogical and Geochemical Studies of Oil Shale Deposits in the Cretaceous/Paleogene succession at Quseir Area, Egypt

Cretaceous/Paleogene succession in Quseir area represents one of the most important economic sedimentary rocks, which contain phosphate and oil shale beds. Oil shale samples selected from nine mines around Quseir area were subjected to mineralogical, petrographical and geochemical analyses. As raveled by X-ray diffraction analysis, the oil shale samples are composed of calcite, quartz, dolomite, smectite, kaolinite, gypsum and pyrite. The petrographical investigation of the studied oil shales indicates the dominance of two microfacies: calcareous foraminiferal claystone and Calci-mudstone. The EDX results of oil shale samples show that the pyrite found as framboidal-disseminated particles in smectite. The high ratio of the sulfur and organic carbon contents in the selected mines indicate highly reducing environment. Five mines (El-Nakheil, Abu Tundub, Abu Tundub Bahree, El Beida and Hammadat) are markedly rich in organic content and can be considered as good to excellent source rock.

Phosphatized tungsten-metabolizing coccoid microbes interpreted from oil shale of an Eocene lake, Green River Formation, Utah, USA.

Microscopic globular structures have been observed in some beds of oil shale from eastern Utah. These beds comprise carbonate-dominated mud that is interlaminated with variably thick and continuous organic-rich layers. Collectively they are enriched in phosphorus, REEs, and actinides. The beds are considered of lacustrine origin and assigned to the Eocene Green River Formation. The globules themselves are of microcrystalline carbonate fluorapatite (μCFA), often contain concentric internal structures, and usually group together in clusters of up to 80, possibly more. Detailed SEM and microprobe analyses have revealed tungsten (W) to be almost exclusively associated with the globular clusters found within the more organic-rich laminae, often at concentrations of over 200ppm, two orders of magnitude above shale standards. The globular structures are present in freshly cut sections where they occasionally grade into a μCFA matrix cement. This, together with the draping of the clusters by stringers of organic matter that would have accumulated in the Eocene lake, confirms that the structures are not a contaminant. The limited range of sizes and globular shapes is consistent with the morphology of coccoidal bacteria: Concentric internal structures may represent remnants of the nucleoid and cell wall. Paired concentric structures may indicate cell division (reproduction) processes were occurring until mineralization. The phosphate mineralization itself may have been promoted by release of phosphate from the stressed cells, bringing porewaters to supersaturation, or by the cells acting as nucleation sites. The recording of trace amounts of W almost exclusively in globular clusters preserved in the most organic-rich stringers (anoxia prone) further suggests facultative use of W-enzymes in a microbial metabolism. Combined, their context, morphology, and indication of biogenic process are strong evidence that the structures are fossilized (phosphatized) microbes, possibly sulfate-reducing bacteria, or methanogenic archaea.

High-precision U-Pb zircon ages for explosive volcanism calibrating the NW European continental Autunian stratotype

Volcanism was intense in western European basins during the Late Carboniferous–Early Permian transition, related to the late Variscan extension and associated magmatism. In the Autun Basin, explosive eruptions, expressed as highly weathered distal ashfall deposits (tonsteins), were preserved in lacustrine to swamp environments. The analysis of eleven tonsteins, confirmed as non-reworked volcanic horizons, indicates a highly explosive acidic calc-alkaline volcanism, with active volcanic centres probably linked to Massif Central or Vosges–Black Forest magmatism. New accurate CA-ID-TIMS U–Pb ages are obtained from four of these tonsteins, recorded within the lower Autunian (Igornay and Muse Fms), which defines the lower part of the Autunian stratotype in the Autun Basin. The middle part of the Igornay Fm is dated at 299.9±0.38Ma, the Lally oil-shale bed is dated at 298.91±0.08Ma and the upper part of the Muse oil-shale bed is dated between 298.05±0.19 and 298.57±0.16Ma. For the first time, a numerical calibration of the regional continental Autunian stage in its stratotype is proposed, thus allowing correlation with global marine stages defined in the Urals, and highlighting a late Gzhelian/early Asselian age for the lower Autunian. The tonstein in the Lally oil-shale appears to demarcate the Carboniferous–Permian boundary within the ±100kyr resolution of the U-Pb ages in both the Autun and southern Uralian basins. Comparison with other European domains confirms that these new ages are consistent with well-known macrofloral assemblages, characteristic of the Autunian.

Pyrolysis of Huadian Oil Shale in an Infrared Heating Reactor

Pyrolysis of Huadian oil shale was investigated in a newly designed shallow fixed bed reactor mounted with infrared heating to clarify the pyrolysis behavior at different heating rates and pyrolysis temperatures under minimized secondary reactions to volatiles in an oil shale bed. The maximum shale oil recovery was obtained under the proper conditions of a heating rate of 0.5 °C/s, a pyrolysis temperature of about 550 °C, a reduced reaction pressure (0.6 atm in this work), and for a single-layer oil shale bed. The highest shale oil yield under such conditions was close to 100% of the Fischer Assay oil yield (11.10 wt % of dry basis). For the adopted infrared-heating reactor, increasing the heating rate decreased the shale oil yield but increased the gas production. The total hydrogen in volatile products including shale oil and pyrolysis gas increased with raising the heating rate, and the total volatile production was higher for the infrared quick heating pyrolysis (heating rate: 25 °C/s) than that for t...

Diagenetic sequestration of rare earths and actinides in phosphatic oil shale from the lacustrine Green River Formation (Eocene), Utah, USA: an SEM and LA-ICP-MS study

The upper Green River Formation of the eastern Uinta Basin of Utah comprises variably organic-rich mudrock deposited in a stratified, alkaline lake that fluctuated in size and in hydrology from open to evaporitic. Beds of oil shale, representing periods of deep lake, suboxic-anoxic deposition include examples with anomalously high phosphate and toxic trace-metal levels, as determined by whole rock X-ray diffraction, scanning electron microscopy (SEM), and both solution and laser-ablation (LA) inductively coupled plasma-mass spectrometry (ICP-MS). The SEM identifies an early, pre-compaction, diagenetic succession of euhedral rhombic dolomite and high-Mg-calcite, nodular pyrite, blocky low-Mg calcite, and microcrystalline carbonate fluorapatite (CFA). LA-ICP-MS indicates the CFA intervals have distinct lower and upper margins where P content rises from ~0.079 to ~3.2% across 2–3 cm of section. Enrichments of rare earth elements (REEs) and actinides (Th, U) show a complex correlation with the phosphatic margins. Light REEs average a tenfold enrichment at the outer margins with progressively heavier REEs exhibiting up to 20-fold enrichment toward the inner margin (Lu from 0.15 to 2.63 ppm). Actinide abundances also increase tenfold (U from ~5 to ~80 ppm) toward the inner margin. There is greatest similarity between Th and the Ho distributions and between U and Lu. This is a similar distribution to what elsewhere has been found in fossil bone and teeth. The microcrystalline CFA is interpreted to have precipitated (or recrystallized from a precursor phosphate) when the rate of dissolved P being generated from organic-matter breakdown exceeded P diffusion rates into the water column, allowing for P supersaturation. As the crystallites grew, diffusion of REE and actinide ions and complexes from surrounding porewaters into the concreting phosphate occurred only until pores were occluded and permeability dropped. As with fossil bone, at the outer margin of the phosphate interval, this allowed for fractionation and preferential substitution of Ca cations in the CFA lattice by light REEs of similar ionic radius. Heavier REEs and actinides of smaller ionic radius diffused further into margin of the phosphate interval.

Oil shale pyrolysis in indirectly heated fixed bed with metallic plates of heating enhancement

This study is devoted to improving the heating to oil shale particles and in turn the yield and quality of shale oil in fixed bed reactors indirectly heated through use of internals. Metallic heating plates were vertically welded on the reactor wall as heating enhancement internals to provide extra heating surfaces inside the oil shale bed and to increase the high-temperature heating surface area by 35% to 210%. Comparison of heating rate to particles and shale oil yield was made between the reactors without and with the plate internals. Utilizing internals evidently enhanced the heating to oil shale particles and shortened pyrolysis time by 30% to 50%. The shale oil yield increased by 7% to reach 90% of the Fischer Assay oil yield (8.98wt.%, dry base) when the heating surface area was increased by 70–110%. With increased heating surface area above 110%, the shale oil yield manifested conversely a slight decrease. Nonetheless, the fraction of light oil (boiling point <350°C by analysis in simulation GC) was increased to about 66wt.% from 60.94wt.% for the reactor without any heating plate. Characterizing the char samples at different lateral positions of the oil shale bed justified that the flow of gaseous pyrolysis product in the reactor was guided to the vicinity of heat transfer plates to speed up gas exhaust and selective cracking. Consequently, adding heat transfer plates into an indirectly heated reactor would obviously intensify the heating to the oil shale bed and also elevate the pyrolysis oil yield and quality.

The Stratigraphic, Mineralogical, and Geochemical Characterization of the Beypazarı Oil Shales, Central Anatolia, Turkey

The Beypazarı-Çayırhan oil shale deposit is situated 100–130 km northwest of Ankara in central Anatolia, within a northeast-southwest-oriented Neogene basin that is approximately 70 km long and 25 km wide. The oil shale beds occur in a thick Late Miocene sequence within the Hırka formation, and were deposited in an extended lake. Besides oil shale, the Neogene basin of Beypazarı also contains lignite, trona, and thenardite as valuable raw materials. The vegetation of the Beypazarı lacustrine basin was dominated by trees, and palynological analysis reveals the existence of a swamp-forest developed in a subtropical to warm-temperate humid climate. Finally, the oil shale of Beypazarı-Çayırhan basin is, on average, of low quality (the average upper calorific value is 840 kcal/kg [= 3.5 MJ/kg] and the oil content is 5.4% respectively 60 l/t), and, due to the tectonic situation, low cost open-cast mining is precluded. Therefore, the industrial utilization of the oil shale is not economical under present conditions and is thus not recommended. This is due to the (1) on-average poor oil shale quality, (2) complicated geologic structure, and (3) necessity of expensive underground mining.

PHYSICAL AND MECHANICAL PARAMETERS OF BOREHOLE HYDRAULIC MINING OF NONG’AN OIL SHALE

The experiments on physics and mechanics of borehole hydraulic mining were designed to determine mechanical characteristics of mined oil shale. Oil shale of Nong'an deposit belongs to slightly weathered and relatively complete rocks. Oil shale beds are characterized by a very definite discontinuity in both horizontal bedding orientation and vertical bedding direction. Compressive strength, tensile strength, Poisson's ratio and other data characterizing oil shale beds in different directions in the Nong'an min- ing site were obtained and compared. The direction of borehole hydraulic mining was determined. The vertical bedding direction to break oil shale was considered to be better, because strength in this direction is low, rock mass integrity poor, and the degree of weathering more pronounced. The diameter of borer nozzle, dynamic pressure, maximum caving capacity and other parameters needed for borehole hydraulic mining were selected.

Microfossils and molecular records in oil shales of the Songliao Basin and implications for paleo-depositional environment

Several oil shale beds, over 10 m thick, occur at the base of the first member of the Upper Cretaceous Qingshankou Formation (K2qn1) in the Songliao Basin. They act both as excellent source rocks for conventional oil and as potential oil deposit for shale oil production. Here we combine micropaleontology with organic geochemistry to investigate the paleo-depositional environment and organic source characteristics of the oil shales and black shales. Our results indicate that algal remains are dominant microfossils in K2qn1 oil shales, and their relatively high abundance suggests a major algal thriving event during the oil shale deposition. The presence of fresh water and brackish water species, Sentusidinium, Vesperopsis and Nyktericysta, and marine or brackish water deltaic and lagoonal species such as Kiokansium and Dinogymniopsis demonstrate that this paleo-continental lake was influenced by marine transgressions at the time of K2qn1 oil shale formation. The extremely low pristine/phytane ratios, relatively high abundance of gammacerane and 4-methyl steranes, and low δ13C values of C14-C37 n-alkanes in the oil shale organic extracts indicate the deposition of oil shales in anoxic and highly stratified water columns and the significant contribution of lacustrine algae to sedimentary organic matter. High molecular-weight paraffinic hydrocarbons with unusually high abundance of nC43, nC45, and nC47 may be related to special algal species associated with marine transgression events. The giant water body of Songliao paleo-lake and the change in the organic and chemical environment (such as nutrition source and water column salinity) associated with seawater transgression into the lake are among the most important reasons for oil shales in the Songliao Basin being different from mudstone and oil shale in other rifted basins.

MINING BLOCK STABILITY PREDICTION BY THE MONTE CARLO METHOD

This paper analyses the stability of the mining blocks by the Monte Carlo method in Estonian oil shale mines, where the room-and-pillar mining system is used. The pillars are arranged in a singular grid. The oil shale bed is embedded at the depth of 40-75 m. The processes in overburden rocks and pillars have caused the subsidence of the ground surface. Visual Basic for Application was used for the modeling. Through Monte Carlo simulation, room-and-pillar stable parameters can be calculated. Model allows determination of the probability of spontaneous collapse of the pillars and surface subsidence by the parameters of registered collapsed mining blocks. Proposed method suits as an express-method for stability analysis and failure prognosis. It is applicable in different geological conditions, where the room-and-pillar mining system is used.

INFLUENCE OF THE BEDROCK TOPOGRAPHY ON OIL SHALE MINING IN NORTH-EAST ESTONIA

According to the zonation of the Estonian bedrock topography, presented on the basis of relative and absolute heights and taking into consideration the lithological composition of the bedrock, Estonian oil shale deposit is located in the Viru-Harju Plateau including the Pandivere Elevation and Ahtme Eminence. The plateau has a thin Quaternary cover, mainly a few metres in thickness. The oil shale basin is dissected by linear structures and ancient buried valleys, which complicate oil shale mining. The buried valleys are eroded into the commercial oil shale beds and serve as natural boundaries between mining and exploration fields. Ancient buried valleys were mainly formed in the Late Paleogene when the Earth’s crust was much higher than at present due to the riftogenesis in the North-Atlantic region. They were overdeepened in the Pleistocene by glaciers. Probably, some valleys are glacial in origin. There are seven bigger valleys (Loobu, Haljala, Selja, Kunda, Pada, Purtse and Vasavere) located in the study area. The valleys contain big reserves of building sand and gravel, and high-quality underground water. Tectonic features, human impact and karst phenomena play an essential role in the formation of the chemical composition of water, especially at local and regional scales.

Controlled heating of reservoirs, coal seams, and oil shale beds for in-situ hydrocarbon recovery

Controlled heating of reservoirs, coal seams, and oil shale beds for in-situ hydrocarbon recovery

Geochemical significance of the aromatic hydrocarbon distribution in the bitumens of the Puertollano oil shales, Spain

The bituminous series of the Puertollano basin consists of three oil shale beds named PA, PB and PC from top to bottom. In this work, results from the study of the aromatic fractions of the bitumens are presented. The gas chromatographic traces are dominated by phenanthrene derivatives associated with variable contributions of arborane/fernane derivatives and benzohopanes and, overall, small amounts of chrysene derivatives and secohopanes. The compounds can be considered as part of two sub-groups: the first one consists of those compounds derived from regular hopanes such as secohopanes, benzohopanes, fully aromatized hopanes, and degradation products of hopanes such as alkylated chrysenes and naphthalenes. The second group is composed of arborane/fernane derivatives and their degradation products such as alkylated phenanthrenes and tetrahydrophenanthrenes. Both groups of compounds appear to be indicative of a strong bacterial input to the sedimentary organic matter.

Comparative petrographic and geochemical study of the Puertollano oil shale kerogens

The bituminous series in the Puertollano oil shale field (central Spain) consists of three oil shale beds named PA, PB and PC from top to bottom. The kerogens from the three oil shales have been studied by microscopy, thermogravimetric analysis, Rock-Eval pyrolysis and Fourier transform infrared (FT-ir) spectroscopy. The shale oils have also been studied by FT-ir, nuclear magnetic resonance spectroscopy and gas chromatography and the results interpreted in terms of variations in palaeoenvironmental conditions and maturity. The three oil shales are dominated by autochthonous algal material (lamalginite and telalginite) in different proportions. The elemental composition of the kerogens and their thermal behaviour are, however, very similar, indicating that both telalginite and lamalginite may represent different growing states of the same algae, Botryococcus. The shale oils show that the kerogens are made up of highly aliphatic, weakly branched macromolecules typical of rocks rich in Botryococcus. Some differences in the chemical composition of shale oils are attributable to the absorptive and catalytic effect of the mineral matter. Some other differences such as the higher carbonyl/carboxyl to aliphatic ratio and the higher degree of substitution of aromatic structures found in the upper oil shale would indicate a slightly lower degree of thermal evolution of this oil shale. This is confirmed by the fluorescence parameters of lamalginite which showed a greenish-yellow hue in the lamalginite from the upper band and a yellow hue in the lamalginite from the two lower beds.

Chitinozoan Biostratigraphy: A Good Correlation Tool for Ordovician Rocks: Case Study of Baltoscandian Oil Shale Interval

Chitinozoans are organic-walled microfossils known from marine sedimentary rocks of Ordovician to Devonian age. In Baltoscandia, chitinozoans have been extensively studied since the 1930s and chitinozoan biostratigraphy of Ordovician-Silurian succession is quite well established. Because the Ordovician-Silurian carbonate sequence contains only a scarce graptolite fauna, chitinozoans and conodonts are considered the most valuable faunal groups for stratigraphic correlation, with the chitinozoans offering even better temporal resolution due to their widespread occurrence, planktonic origin, and relatively easy taxonomy. Also, small samples (100-300 g) can yield several hundreds of chitinozoans. In this study, chitinozoan distribution is compared in two Middle Ordovician (Llanvirn to Caradoc) core sections: Tamsalu-565 (central Estonia) and Bliudziai-150 (southern Lithuania). The distance between studied sections is about 470 km. The studied intervals are 51 and 27 m thick in the Tamsalu-565 and Bliudziai-150 cores, respectively. Both sections are highly condensed with numerous hardgrounds, but without major hiatuses. The Tamsalu-565 borehole was drilled in the Tapa oil shale deposits and contains 17 kukersite-type oil shale beds up to 2.3 m thick. Both sections yielded a numerous and diverse chitinozoan fauna. Altogether, 14 genera and 55 species were recorded. Although many chitinozoan species are long ranging, several with limited vertical rangemore » are useful biostratigraphically and suggest a good correlation between the studied sections. Chitinozoans can be regarded as a perspective faunal group in the United States for correlating subtidal to basin carbonate sediments, particularly when small sample size is a critical factor.« less

Composition and depositional environment of major eastern Canadian oil shales

In Eastern Canada, following the Acadian Orogeny, two lithologically and chronologically distinct sequences of oil shale were deposited in the Late Devonian/Carboniferous Maritimes Basin. The oldest sequence occurs within the Moncton Subbasin, a transcurrent and asymmetric basin 200 km in length in southeastern New Brunswick. The oil shales are largely confined to the medial part of the 165–1800 m thick Early Carboniferous (Tournaisian) Albert Formation. The oil shales range from massive slightly organic-rich dolostone to carbonate-rich lamosite with an organic fraction of 1–30% TOC and comprising mainly alginite with locally abundant liptodetrinite and vitrinite. Rock-Eval and chromatography data indicate mostly Type I and Type II kerogens. Lamalginite fluorescent spectra indicate immature to mature sediments, in agreement with surface oil shows and the presence of a small oil and gas field sourced from Albert oil shales. The oil shale composition reflects deposition in a chemically stratified lacustrine setting characterized by slightly saline and alkaline waters and deltaic sedimentation. The younger sequence occurs within the Stellarton Basin, a 6×18 km pull-apart basin situated in northern Nova Scotia. The oil shales form part of the 2600 m thick Late Westphalian B-Early Westphalian D coal-bearing Stellarton Formation; a total of 60 oil shale beds (1–45 m thick), some transitional to coal, have been documented. The oil shale lithotypes are silicate-rich and include fissile shale, minor blocky (cannel) shale and lesser stellarite (boghead shale) with an organic fraction, depending upon lithotype, of 1–41% TOC comprising variable amounts of liptinitic groundmass material, telalginite and vitrinite. Rock-Eval, petrography and gas chromatography, data indicate mature Type II and locally Type I and Type III kerogens. Extract, chromatography and carbon isotope data indicate that the coals of the formation, rather than the oil shales, are the most probable source of the hydrocarbon shows within the Stellarton Formation. The composition of the oil shales and the transition of some oil shales to coal reflects deposition in a nearshore to open lacustrine environment bordered by peat swamps. The principal causes for compositional differences between the Albert and Stellarton oil shales are: (1) the influence of basin size and paleogeographic setting on sediment supply to the Albert and Stellarton lakes; (2) the hydrological conditions (closed versus open) of the Albert and Stellarton lakes; (3) the influence of swamps on the pH and organic content of the Stellarton lakes; and (4) climate.

Fluorescence properties of alginite-rich oil shales from the Stellarton Basin, Canada

Oil shale beds from the Stellarton Basin, Nova Scotia were characterized using macroscopic and microscopic fluorescence properties of the organic material and by Rock-Eval analysis techniques. Results from image analyses show that the distinct fluorescing layering observed when the rocks were irradiated with ultraviolet light is related to differences in alginite contents contained in the oil shales. Comparison with Rock-Eval analyses shows that total organic carbon contents and oil and gas potentials correlate well with microscopically determined alginite contents. Macroscopic examination of oil shale beds during ultraviolet excitation may thus be used as a fast screening method to assess oil shale quality.

Geology and organic petrography of the Nagoorin oil shale deposit

An in-situ shale oil resource of 2.65 × 10 9 barrels has been delineated by exploratory drilling in the northern part of the Nagoorin Graben known as the Nagoorin deposit. The drilling has defined a mid to late Eocene sedimentary sequence in excess of 870 m thick. The Tertiary rocks have been divided into five conformable sedimentary units (B to F) and, with the exception of the basal unit B, all contain significant beds of oil shale. Eighty samples from the deposit, examined using fluorescence microscopy for the included organic matter, with specific reference to the nature of the liptinite macerals, are shown to belong to one of three groups: 1. cannel coals and canneloid carbonaceous shales-generally dull, black in colour but containing bright vitrinite bands up to 2 mm thick; 2. lamosites and carbonaceous lamositesbrown to dark greyish-brown oil shales containing dominantly lamalginite but also minor vitrinite; and 3. claystones and carbonate-rich claystones containing trace amounts of alginite, vitrinite and resinite.