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1.
Combining vitrinite reflectance (VR) and fluorescence alteration of multiple macerals (FAMM) analyses provide insights into the chemical nature of vitrinites (i.e., perhydrous vs. orthohydrous vs. subhydrous compositions) in Permian Gondwana coals of the Paraná Basin, Brazil. The FAMM-derived equivalent VR (EqVR) values and relationships with VR can be determined according to calibration curves based largely on Permian Gondwana coals of eastern Australia.The analytical results indicate that vitrinites in the Paraná Basin coals studied generally range from orthohydrous to perhydrous, with interpreted VR suppression ranging up to 0.2% absolute for the most perhydrous case. The EqVR values of the Santa Catarina coals, which range from about 0.85% to 0.95% differ from VR values by about 0.10–0.15% absolute, potentially having significant implications on coal utilization.The causes of vitrinite reflectance suppression in the Paraná Basin coals are as yet poorly understood, but are likely to be related to a combination of factors.  相似文献   

2.
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3.
Six North American bituminous coals (four Carboniferous and two Cretaceous) and eight maceral concentrates from Carboniferous British seams have been heated with tetralin and hydrogen to 400°C. The hexane-soluble parts of the products were separated by column chromatography and the fractions were then analyzed by gas chromatography/mass spectrometry. In all cases the aromatic hydrocarbon fraction was a very complex mixture containing a number of alkylated biphenyls, diphenylmethanes and -ethanes, and polycyclic compounds. However single ioncchromatography (m/z = 142) showed that, in addition to these, the products from five of the six American coals contained homologous series of long chain n-alkylnapththalenes with alkyl groups extending to C16. In other fractions from the American coals, homologous series of n-alkylfurans and alkylphenols were found to be major components, as also were many alkylcyclohexenones related to isophorone. Extensive homologous series of n-alkyl aromatics were not detected in products from any of six vitrinites from British seams, though series of n- and iso-alkylphenols were found in the products from two sporinite concentrates. A number of polycyclic ketones apparently related to sterols were found in the products from the British vitrinites but not from any American coals. Reasons for what appear to be systematic structural differences between the American and British coals are discussed. Differences in stratigraphy are noted and it seems not impossible that differences in source vegetation are significant.  相似文献   

4.
Proposals for new scientific classifications of bituminous coals are based on micropetrographic parameters, i.e. vitrinite reflectance as a criterion of the coalification and maceral composition, presupposed to express the connection between the genetic peculiarities and physical, chemical, and technological properties of the coal mass. In the case of coals with high inertinite contents, however, the utilizability of these parameters meets with difficulties resulting from the subjectivity of determining the different transitional material and from insufficient knowledge of inertinite behaviour at higher temperatures. In the case of the maceral-variable bituminous coals produced in the Ostrava-Karviná Coal Basin, these insufficiencies are not important since it is especially the expression of the variability of the properties of isometamorphic vitrinites, which has decisive effects up-on the course of the thermo-chemical transformations, that is of principal importance to the scientific classification of these coals.In the first approximation, the properties of isometamorphic vitrinites may be expressed by the parameter (H/O)at, closely connected with fluidity. While the micropetrographic parameters reflect in particular the peculiarities in the chemical structure of the aromatic parts of coal macromolecules, the parameter (H/O)at expresses the properties of the non-aromatic structures of vitrinite, significantly affecting the course of its thermal degradation. The experimental results show that the value of the parameter (H/O)at, fluidity and the course of degassing the coal of a lower coalification are independent of the maceral composition and vitrinite reflectance; also that the caking and coking properties of low-rank coals are especially dependent on the parameter (H/O)at and partially on the micropetrographic parameters. All these facts should be taken into consideration in preparing new scientific classifications of bituminous coals.  相似文献   

5.
A series of hand-picked vitrinite samples from the Lower Kittanning Seam, Pennsylvania have been examined using quantitative pyrolysis-gas chromatography. These vitrinites ranged in rank from 0.59 to 1.71% reflectance, a rank range from high volatile C bituminous to low volatile bituminous. High molecular weight pyrolysis products included alkyl aromatic and phenolic compounds. Attempts have been made to correlate the pyrolysis product composition to rank parameters including vitrinite reflectance, volatile matter yield, carbon content, atomic H/C ratio and Rock-Eval determined Tmax. Total yield of phenols was found to be strongly and inversely rank related. A clear relationship between C8 alkyl-benzene yield and rank was not found for the sample set.  相似文献   

6.
Thermally metamorphosed Tertiary age coals from Tanjung Enim in South Sumatra Basin have been investigated by means of petrographic, mineralogical and chemical analyses. These coals were influenced by heat from an andesitic igneous intrusion. The original coal outside the metamorphosed zone is characterized by high moisture content (4.13–11.25 wt.%) and volatile matter content (> 40 wt.%, daf), as well as less than 80 wt.% (daf) carbon and low vitrinite reflectance (VRmax = 0.52–0.76%). Those coals are of subbituminous and high volatile bituminous rank. In contrast the thermally metamorphosed coals are of medium-volatile bituminous to meta-anthracite rank and characterized by low moisture content (only < 3 wt.%) and volatile matter content (< 24 wt.%, daf), as well as high carbon content (> 80 wt.%, daf) and vitrinite reflectance (VRmax = 1.87–6.20%). All the studied coals have a low mineral matter content, except for those which are highly metamorphosed, due to the formation of new minerals.The coalification path of each maceral shows that vitrinite, liptinite and inertinite reflectance converge in a transition zone at VRmax of around 1.5%. Significant decrease of volatile matter occurs in the zone between 0.5% and 2.0% VRmax. A sharp bend occurs at VRmax between 2.0% and 2.5%. Above 2.5%, the volatile matter decreases only very slightly. Between VRr = 0.5% and 2.0%, the carbon content of the coals is ascending drastically. Above 2.5% VRr, the carbon content becomes relatively stable (around 95 wt.%, daf).Vitrinite is the most abundant maceral in low rank coal (69.6–86.2 vol.%). Liptinite and inertinite are minor constituents. In the high rank coal, the thermally altered vitrinite composes 82.4–93.8 vol.%. Mosaic structures can be recognized as groundmasss and crack fillings. The most common minerals found are carbonates, pyrite or marcasite and clay minerals. The latter consist of kaolinite in low rank coal and illite and rectorite in high rank coal. Change of functional groups with rank increase is reflected most of all by the increase of the ratio of aromatic C–H to aliphatic C–H absorbances based on FTIR analysis. The Oxygen Index values of all studied coals are low (OI < 5 mg CO2/g TOC) and the high rank coals have a lower Hydrogen Index (< 130 mg HC/g TOC) than the low rank coals (about 300 mg HC/g TOC). Tmax increases with maturity (420–440 °C for low rank coals and 475–551 °C for high rank coals).Based on the above data, it was calculated that the temperature of contact metamorphism reached 700–750 °C in the most metamorphosed coal.  相似文献   

7.
n-Alkanes in the soluble organic matter extracted from a series of vitrinite and sporinite concentrates have been analysed by gas chromatography. The macerals were isolated from coals ranging in rank from 77.1% to 86.6% carbon (vitrinite: dry, ash-free), and yields of n-alkanes ranged from 10 to 580 ppm for vitrinites and from 20 to 970 ppm for sporinites. The maximum yields were found at a rank of 85.4% C from vitrinites and 86.6% C from sporinites.Distribution maxima of the n-alkanes, as shown by gas chromatography, range from C27 and C29 at lower ranks to as low as C16 at higher ranks. The distributions also show a progressive decrease in the preference of odd-carbon-number homologues with increasing rank. Virtually smooth distributions were attained in high-volatile bituminous A coals. Quantitative data show that the loss of the odd-carbon-number preference occurred, for the most part, while individual long-chain homologues increased in concentration.There is a progressive increase in the amounts of shorter-chain n-alkanes with increasing rank. It is suggested that sequential processes may have occurred whereby the rate of formation of long-chain n-alkanes in high-volatile bituminous A rank macerals becomes slower than their rate of subsequent fragmentation to shorter chain lengths. Consequently, assuming derivation from the insoluble maceral matrices, the chain-length distributions of parent n-alkyl structures within the insoluble material may retain characteristics pertaining more to the nature of the source organic matter at the time of deposition than do the extractable n-alkane patterns, especially at higher ranks.  相似文献   

8.
煤镜质组反射率光性组构变形实验研究   总被引：5，自引：0，他引：5  
不同煤级煤的高温高压实验表明，在温、压和差异应力作用下，煤镜质组反射率值和各向异性都有一定程度增加，变形越强烈，增加越明显，尤其在中煤级中、晚期阶段更是如此。在变形过程中，反射率主轴将发生有规律的偏转，变形越强烈，最小反射率主轴越接近于最大挤压应力方向。随着变形的增强，镜质组反射率椭球由单向伸长同压缩型转化。  相似文献   

9.
Petrographic analyses were carried out on thin coals and coaly sediments from the Lower Carboniferous Mattson Formation at Clausen Creek and Jackfish Gap-Yohin Ridge in the northern part of the Liard Basin, northern Canada. The composition and optical characteristics indicate that the coals are high-volatile bituminous B, predominantly sapropelic (canneloid) and accumulated subaquatically.The coals are dominantly composed of inertinite-rich and exinite-rich durities with subsidiary inertites and clarodurites; vitrite is minor and liptite is rare. The inertinite-rich microlithotypes are dominated by semifusinite, but micrinite, semimacrinite and ?resino-inertinites are abundant. Sporinite, comprising megaspores, crassispores, tenuispores and miospores, is the dominant liptinite maceral with subsidiary cutinite and minor alginite. Except for pyrite, mineral matter is minimal.Three populations of telocollinite are observed: a low-reflectance variety (I), commonly associated with micrinite (as vitrinertite), displays weak brown fluorescence and a reflectance some 0.4-0.5% lower than type II; type II is non-fluorescing telocollinite, with intermediate reflectance (0.67-0.74% Rom), it occurs as vitrite and is also associated with micrinite; and a higher-reflectance telocollinite (III), having no fluorescence or association with micrinite, has variable reflectance (0.74-0.8% Rom) implying higher oxidation or gelification levels.The abundance of semimacrinite, macrinite and ?resino-inertinites in inertites and durites (I) suggests that much of the peat accumulated subaquatically. Furthermore, fluorescing vitrinite and an abundance of micrinite (derived by oxidation or coalification of bituminite), suggest that the coal accumulated under anaerobic conditions. The predominance of semifusinite in humic laminae and micrinite in sapropelic layers suggests extensive surface or near-surface oxidation of the peat. Oxidised sporinites suggest that they were wind-borne.Depositional environment is interpreted as marginal marine, perhaps in shallow lakes in the middle to upper delta plain. Peat accumulations probably began subaquatically at the oxygen-hydrogen sulphide interface, but periodic subaerial exposure and natural oxidation gave rise to the high inertinite coals. Upper Mattson coals are interbedded with algal laminites and probably accumulated in a lagoonal setting.  相似文献   

10.
The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation. The same statistical approach as that followed in the ICCP vitrinite reflectance accreditation program for single seam coals has been used for data evaluation. The results indicated low to medium dispersion for 17 out of 22 participants. This, combined with data from other sets of comparative analyses over a long period, is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter.  相似文献   

11.
A set of 30 maceral concentrates consisting of 5 exinites (sporinites), 14 vitrinites and 11 inertinites (fusinites and semifusinites) was analyzed by Curie-point pyrolysis mass spectrometry in combination with computerized multivariate statistical analysis techniques. Seventeen samples, representing sink/flotation concentrates of 7 different coals, were obtained through the British National Coal Board, whereas the remaining samples represent cesium-chloride density-gradient centrifugation fractions of two different U.S. coals prepared at the University of Utah.It is found that vitrinites, (semi)fusinites and, to some extent, sporinites show qualitatively similar rank-related changes, such as a decrease in dihydroxybenzene signals and an increase in napthalene signals with increasing rank. In fact, the overall pyrolysis MS patterns of inertinities show a close similarity to those of vitrinites of corresponding carbon content (as obtained from higher rank coals).Notwithstanding these similarities, however, the presence of basic differences in maceral structure is indicated by relatively minor but characteristic peak series in the liptinite (sporinite) as well as inertinite samples. Whereas inertinite spectra show relatively pronounced peak series at the high mass end of the spectrum which can be tentatively identified as representative of polynuclear aromatic compounds, sporinites are characterized by series of branched aliphatic and/or alicyclic polyenic hydrocarbons, possibly representing isoprenoids and related biomarker compounds.  相似文献   

12.
试论等变质煤镜质体性质差异之普遍性   总被引：1，自引：1，他引：0  
选择了不同地区和时代的不同变质程度的5个系列的煤样,对分离富集的镜质体主要特征进行了比较研究。研究发现:按海相和陆相划分,属同一相的不同时代的等变质煤的镜质体性质仍有差异,有些甚至相当明显。这表明,等变质煤镜质体性质存在的差异具有普遍性,并且其成因不止有煤相一个因素。   相似文献   

13.
Sorption and desorption behaviour of methane, carbon dioxide, and mixtures of the two gases has been studied on a set of well-characterised coals from the Argonne Premium Coal Programme. The coal samples cover a maturity range from 0.25% to 1.68% vitrinite reflectance. The maceral compositions were dominated by vitrinite (85% to 91%). Inertinite contents ranged from 8% to 11% and liptinite contents around 1% with one exception (Illinois coal, 5%). All sorption experiments were performed on powdered (−100 mesh), dry coal samples.Single component sorption/desorption measurements were carried out at 22 °C up to final pressures around 51 bar (5.1 MPa) for CO2 (subcritical state) and 110 bar (11 MPa) for methane.The ratios of the final sorption capacities for pure CO2 and methane (in molar units) on the five coal samples vary between 1.15 and 3.16. The lowest ratio (1.15) was found for the North Dakota Beulah-Zap lignite (VRr=0.25%) and the highest ratios (2.7 and 3.16) were encountered for the low-rank coals (VRr 0.32% and 0.48%) while the ratio decreases to 1.6–1.7 for the highest rank coals in this series.Desorption isotherms for CH4 and CO2 were measured immediately after the corresponding sorption isotherms. They generally lie above the sorption isotherms. The degree of hysteresis, i.e. deviation of sorption and desorption isotherms, varies and shows no dependence on coal rank.Adsorption tests with CH4/CO2 mixtures were conducted to study the degree of preferential sorption of these two gases on coals of different rank. These experiments were performed on dry coals at 45 °C and pressures up to 180 bar (18 MPa). For the highest rank samples of this sequence preferential sorption behaviour was “as expected”, i.e. preferential adsorption of CO2 and preferential desorption of CH4 were observed. For the low rank samples, however, preferential adsorption of CH4 was found in the low pressure range and preferential desorption of CO2 over the entire pressure range.Follow-up tests for single gas CO2 sorption measurements consistently showed a significant increase in sorption capacity for re-runs on the same sample. This phenomenon could be due to extraction of volatile coal components by CO2 in the first experiment. Reproducibility tests with methane and CO2 using fresh sample material in each experiment did not show this effect.  相似文献   

14.
The maceral and microlithotype composition of selected coals has been investigated with respect to the grinding properties, specifically Hardgrove grindability index (HGI), of the coals. The study expands upon previous investigations of HGI and coal petrology by adding the dimension of the amount and composition of the microlithotypes. Coal samples, both lithotypes and whole channels, were selected from restricted rank ranges based on vitrinite maximum reflectance: 0.75–0.80% Rmax, 0.85–0.90% Rmax and 0.95–1.00% Rmax. In this manner, the influence of petrographic composition can be isolated from the influence of rank. Previous investigations of high volatile bituminous coals demonstrated that, while rank is an important factor in coal grindability, the amount of liptinite and liptinite-rich microlithotypes is a more influential factor. In this study, we provide further quantitative evidence for the influence of microlithotypes on HGI and, ultimately, on pulverizer performance.  相似文献   

15.
Summary The Brazilian test is a widely accepted method for the determination of the tensile strength of intact rock. Specifications for the Brazilian tensile strength test have been established by the American Society for Testing and Materials (ASTM), ASTM D 3967-86 and a suggested approach is provided by the International Society for Rock Mechanics (ISRM). The ASTM and ISRM allow a relatively wide range of values for specimen geometry defined in terms of length to diameter ratio and loading rates defined as either time to failure or stress rate.A statistical study was carried out on a coal measure sandstone to determine whether the tensile strength determined by the Brazilian test is independent of the specimen geometry and the stress rate.  相似文献   

16.
An attempt has been made to study the petro-chemical characteristics of some high sulphur sub-bituminous coal samples from Makum coalfield, Assam, India. The proximate and ultimate analyes were carried out and forms of sulphur were determined and their relationships with the Maceral constituents (vitrinite, liptinite, and inertinite) were investigated. The macerals (vitrinite+liptinite+inertinite) have significant relationships (R2>0.500) with volatile matter and carbon, whereas weak correlations were seen with rest of the physico-chemical characteristics of the coals. The study reveals that these coals are rich in vitrinites and sulphur and are aromatic in nature. These coals have good hydrocarbon potential.  相似文献   

17.
Ten sub-bituminous coals were analyzed petrographically and chemically as part of a program by the Alberta Research Council to investigate the compositional properties of Alberta coals and relationship to liquefaction potential. In addition, four lignites, two from Saskatchewan and one each from Texas and North Dakota, were studied for comparative purposes. Liquefaction experiments were carried out on three of the Alberta coals and on density fractions of the two U.S. lignites. Petrographically the ten sub-bituminous coals could be divided into two populations; one with high huminite and liptinite contents (>90%) and one with substantially lower contents (70–75%). The two U.S. lignites showed huminite plus liptinite contents of less than 70% while the Saskatchewan coals were somewhat higher. Reflectance measurements on the sub-bituminous coals showed a range of 0.33 to 0.51 with a rough correlation to the ASTM rank designations of these coals. Reflectivities determined on the lignites were generally lower. Float-sink fractionation of the two U.S. lignites and two sub-bituminous coals showed enrichment of huminite and liptinite in the lighter fractions and inertinite and mineral matter in the heavier splits. Examination of the relationship between liquefaction yields and petrographic composition showed a rough positive correlation with huminite-liptinite content. Examination of liquefaction residues suggested total conversion of the liptinite, extensive conversion of huminite and possible partial conversion and reactivity of the semifusinite maceral of the inertinite group.  相似文献   

18.
Optical and chemical properties for hand-picked samples of vitrinite from a number of British coalfields are correlated and the correlations compared with previously published data. The form of the relationship found for the properties of British vitrinites is generally similar to that exhibited by a number of other sets of analyses, but some significant differences also exist in several of the correlations. For maximum reflectance as a function of carbon content, the present data indicate that at medium and low ranks, maximum reflectance is lower than the level suggested by most previous studies. The relationships of volatile-matter yield to reflectance and carbon content suggest that at low ranks, volatile-matter yield is strongly dependent upon the nature of the coalification history of the vitrinite. Furthermore, these correlations are likely to show provincialism, in that correlations which hold for one coalfield may not be representative of the relationship in other coalfields. Similarly, major differences in relationships involving bireflectance are associated with the tectonic setting at the time of effective coalification. The data presented here indicate that for low-rank coals at least, correlations between properties of vitrinites must take account of provincialism if they are to be sufficiently reliable to be useful. The measurement of a number of rank-sensitive variables can yield additional information about rank, as compared with the use of a single rank-sensitive variable.  相似文献   

19.
The aim of the present study is the petrographic and chemical characterization of the coal at the Figueira Power Plant, Paraná, Brazil, prior and after the beneficiation process and the chemical characterization of fly and bottom ashes generated in the combustion process.Petrographic characterization was carried out through maceral analysis and vitrinite reflectance measurements. Chemical characterization included proximate analysis, determination of calorific value and sulphur content, ultimate analysis, X-ray diffraction, X-ray fluorescence, Inductively Coupled Plasma — Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma — Atomic Emission Spectrometry (ICP-AES) analysis, and determination of Total Organic Carbon (TOC) content.Vitrinite reflectance analyses indicate a high volatile B/C bituminous coal (0.61 to 0.73% Rrandom). Maceral analyses show predominance of the vitrinite maceral group (51.6 to 70.9 vol.%, m.m.f). Except of the Run of mine (ROM) coal sample, the average calorific value of the coals is 5205 kcal/kg and ash yields range from 21.4 to 38.1 wt.%. The mineralogical composition (X-ray diffraction) of coals includes kaolinite, quartz, plagioclase and pyrite, whereas fly and bottom ashes are composed by mullite, ettringite, quartz, magnetite, and hematite. Analyses of major elements from coal, fly and bottom ashes indicate a high SiO2, Al2O3, and Fe2O3 content. Trace elements analysis of in-situ and ROM coals by ICP-MS and ICP-AES show highest concentration in Zn and As. Most of the toxic elements such as As, Cd, Cr, Mo, Ni, Pb, and Zn are significantly reduced by coal beneficiation. Considering the spatial distribution of trace elements in the beneficiated coal samples, which were collected over a period of three months, there appears to be little variation in Cd and Zn concentrations, whereas trace elements such as As, Mo, and Pb show a larger variation.In the fly and bottom ashes, the highest concentrations of trace elements were determined for Zn and As. When compared with trace element concentrations in the feed coal, fly ashes show a significant enrichment in most trace elements (As, B, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Tl, and Zn), suggesting a predominantly volatile nature for these elements. In contrast, Sn is distributed evenly within the different ash types, whereas U shows depleted concentration in both bottom and fly ash samples.According to the International Classification of in-seam coals the Cambuí coals are of para/ortho bituminous rank of low grade (except for the ROM sample), and are characterized by the predominance of vitrinite macerals.  相似文献   

20.
Selected Tertiary coals from the Zeya–Buryea Basin, Far Eastern Russia, were investigated for aspects of their coal type, rank, depositional environment and post-depositional history. The coals have been examined in outcrop (lithotype logging), microscopically (maceral, reflectance and fluorescence), and geochemically (proximate analysis).Two laterally extensive coal-bearing horizons occur: one of Palaeocene age and the other of early Miocene age. The Palaeocene coals were investigated in active open-cut mines at Raichikhinsk and Yerkovtsi and the early Miocene deposit in an abandoned open-cut mine at Cergeyevka.Palaeocene coals at Raichikhinsk and Yerkovtsi were indistinguishable from each other macroscopically, microscopically, and geochemically. The deposits were sufficiently coalified that brightness logging could be undertaken. Dull coals, with numerous fusainous wisps, were dominant. Four dulling-up sequences, which represent stacked peat deposits, were observed at Raichikhinsk. At Yerkovtsi, only a small section of the middle of the seam, which was mostly dull and muddy coal, was investigated. Petrographically, these coals were dominated by inertinite group macerals, which is unusual in non-Gondwanan coals and rare in the Tertiary. Rank classification was problematic with volatile matter (VM) content of vitrain (daf), macroscopic appearance, and microscopic textures suggesting subbituminous B rank, but carbon content, moisture content and specific energy indicating a lignite rank.Notwithstanding complications of rank, estimates of the maximum-range burial depths were calculated. Taking the VM (daf) content of vitrain as 48%, burial depth estimates range from 900 m for a high geothermal gradient and long heating time to a maximum of 3300 m for a low geothermal gradient and short heating time. These estimates are maxima as the coal rank may be lower than implied by the VM.The Cergeyevka deposit is a soft brown coal. Limited sampling of the upper-most portion indicated a high moisture content (75% daf) and an unusual, hydrogen-rich geochemistry. Lack of identifiable liptinites using either reflected light or fluorescence microscopy suggested a significant bituminite component. Otherwise, the coals appear to be typical for the Tertiary. An estimate of 125 m maximum burial depth was obtained using the bed-moisture content of the coal, which is around the present burial depth.Comparison of present-day thicknesses with inferred burial depths suggests that at least 500 m of section is missing between the Palaeocene coals and the early Miocene coals.Palaeoenvironmental considerations suggest that fire played a significant role in the accumulation of the peats at Raichikhinsk and Yerkovtsi. At Cergeyevka, peat accumulation ended by drowning of the mire.Two tuff beds were recognised within the seam at Raichikhinsk and one in the seam at Yerkovtsi. Correlation of the tuff beds is uncertain but they should prove useful in regional coal seam correlation and interpreting coal depositional environments. Geochemical analysis by XRF was complicated by high loss-on-ignition (LOI) values. Despite extensive alteration, an acid igneous source is implied from the presence of free quartz and TiO2/Al2O3 ratios of 0.02 to 0.05.  相似文献   

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