Geochemical and petrographic properties of some Spitsbergen coals and dispersed organic matter

International Journal of Coal Geology 57 (2004) 77 – 97 www.elsevier.com/locate/ijcoalgeo

Geochemical and petrographic properties of some Spitsbergen coals and dispersed organic matter Stanislaw R. C´miel, Monika J. Fabian´ska * Department of Geochemistry, Mineralogy and Petrography, Faculty of Earth Sciences, University of Silesia, Beßdzin´ska Street 60, Sosnowiec 41-200, Poland Received 2 August 2002; received in revised form 8 September 2003; accepted 9 September 2003

Abstract This paper presents the characteristics of selected parameters of organic matter of the Tertiary coal samples and organic matter of Carboniferous rock samples from the Spitsbergen. The coal samples were taken from Central Coal Basin (the Longyearbyen region) and from the Forlandsundet Basin (Oscar II Land, the Kaffioyra region). Samples of dispersed organic matter were collected from Suffolk Pynten and Sergeijevfjellet area in Sorkapp Land. The optical properties of coal samples are different from properties of dispersed organic matter. Macerals of vitrinite group dominate in all of the samples. The average content of vitrinite group macerals is much lower in dipersed organic matter samples than it is in coals. The average content of liptinite group macerals is a little lower, and inertinite group macerals is much higher. The average content of mineral matter is higher in organic matter samples than in coal samples. The average value of vitrinite reflectance and standard deviation of organic matter is higher in comparison with coals. The coal samples are generally classified as orthobituminous, medium rank type C. There are samples from very low- to middle-grade coal. The values of vitrinite reflectance and standard deviation of coals investigated are similar and are lower than they are in dispersed organic matter. Gas chromatography – mass spectrometry (GC-MS) was applied to assess organic matter source and rank with use of several biomarker parameters. Primary organic matter of the Tertiary coals contained predominantly material from conifers, among them, Cupressaceae and/or Taxodiaceae and Podocarpaceae families were identified by their characteristic biomarkers. Dispersed organic matter of rocks does not show features indicating input of vascular plants into its primary material, and its origin is assumed to be algal/bacterial. Samples with Calamites fossils contained organic matter with only low terrestrial input. Results of rank assessment by thermal maturity parameters based on biomarkers agree with vitrinite reflectance data: the Kaffioyra and the Longyearbyen coals are in the range of high volatile bituminous coals. The dispersed organic matter samples seems to be more mature than that of both coals and can be assessed as late catagenetic. The organic matter of the Sergeijevfjellet Formation was formed in basins with higher fluctuation of water level; lower amount of water caused oxidation of organic matter in a basin. The mire plants contained less of resins and essential oils than Hornsundneset Formation mire plants. The deposits of organic matter in a Tertiary basin were formed with faster subsidence and higher water level. The plants of Oligocene age (Kaffioyra region) contain more resins and essential oils than plants of Paleocene age (Longyearbyen region), while coalification degree is similar. However, technological parameters of Paleocene coals are

* Corresponding author. Tel.: +48-32-291-83-81, +48-32-291-89-01-9x244/228; fax: +48-32-291-58-65. E-mail addresses: [email protected] (S.R. C´miel), [email protected], [email protected] (M.J. Fabian´ska). 0166-5162/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.coal.2003.09.002

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better. The organic matter of Kaffioyra region was formed in basins with higher fluctuation of water level than from the Longyearbyen region. D 2004 Elsevier B.V. All rights reserved. Keywords: Spitsbergen coal; Dispersed organic matter; Biomarkers

1. Introduction 1.1. Geological background In the entire Svalbard archipelago, Tertiary sediments exist only on Spitsbergen and Prins Karls Forland (Fig. 1). The Tertiary geology of the investigated part of Spitsbergen has been the subject of

several publications: Atkinson (1963), Vonderbank (1970), Birkenmajer (1972), Major and Nagy (1972), Kellogg (1975), Croxton and Pickton (1976), Manum and Throndsen (1978), Nemec (1985), Tonseth (1981), Michelsen and Khorasani (1991) and Harland (1997). The main Tertiary deposits occur in the central part of Spitsbergen in a large depression with a NNW-

Fig. 1. The Carboniferous and Tertiary deposits on Spitsbergen and sample locations sketch (after Harland, 1997, modified).

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trending axis. Tertiary rocks in the central part of the depression exceed 2300 m in thickness. They consist of conglomerates, sandstones, siltstones, claystones, coaly shales and coals. Paleogene strata with coal are found in three main basin areas (Harland, 1997). The Central Basin (the middle part of Spitsbergen area, Nordenskiold, Nathortst and Torell Land) is the principal onshore outcrop of Paleogene strata and the uppermost unit of the basin called the Van Mijenfiorden Group. The small areas of Tertiary deposits occur the western part of Oscar II Land and the eastern part of Prins Karls Forland (the Forlandsundet Basin) as well as the northwestern part of Wedel Jarlsberg Land (Calypsostranda Basin). The Forlandsundet Basin on the east side exposes the Balanuspynten Formation whose Sarsbukta Member contains coal and plant fragments defining thin seams of up to 0.15 m. There is no prospect of coal mining. The Buchananisen Group (previously the Forlandsundet Group) belonging to Eocene and Oligocene age has been divided into seven formations (Table 1). Among them, the Sarsbukta Member consists only of coal seams. The Calypsostranda Basin in the Skilvika Formation contains many thin coal horizons, which were the basis of short-lived exploitation at Calypsobyen. The seams are mostly thin, and three of them attained only 0.5 –0.6 m thickness. The Central Basin is a N –S brachy-syncline of the mid-Eocene to Paleocene Van Mijenfjorden Group. The Kings Bay Coalfield (Ny-Alesund) determines a northwest part of the Central Basin, and most authors include these strata in the Van Mijenfiorden Group. The sequence of Paleogene deposits, the Van Mijenfiorden Group, has been divided into six lithologic formations (Table 1). Among them, coal has been recorded in the Firkanten, Grumantbyen, and Aspelintoppen Formations. The Paleocene Firkanten Formation is the principal source of coal in Spitsbergen, being mined at Longyearbyen, Barentsburg and Sveagruva. There are five seams, starting from the top: Askeladden, Svarteper, Longyear, Todalen and Svea. The coal samples investigated in this study were collected in the middle part of the Central Basin in the Longyearbyen region and in the northwest part of the Forlandsundet Basin (the western part of Oscar II Land) in the Kaffioyra region. There are only few publications concerning quality of Tertiary coals in

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Table 1 The stratigraphic position of samples investigated (after Harland, 1997, modified) Buchananisen Group Kaffioyra region Age

Formation

Member

Ol

Balanuspynten

Sarstangen Sarsbukta

E

Marchaislaguna Krokodillen Reinhardpynten Sesshogda Selvagen Aberdeenflya

Van Mijenfjorden Group Longyerbyen region Age

Formation

E

Aspelintoppen Battfjellet Frysjaodden Grumantbyen Basilika Firkanten

Pc

Member

Endalen Kolthoffberget Todalen

Billefjorden Group Sorkapp Land region Age

Formation

C2 C1

Sergeijevfjellet Hornsundneset Adriabukta

Spitsbergen. The most comprehensive studies to date are by Harland et al. (1976), Harland (1997), Manum and Throndsen (1978), Dalland (1979), and Michelsen and Khorasani (1991). The rocks samples were collected in the Sorkapp Land in the Mississippian (late Visean) Hornsundneset Formation and in the Pennsylvanian (early Namurian) Sergeijevfjellet Formation (Siedlecki, 1960; Birkenmajer, 1964; Lipiarski and C´miel, 1984). Those rocks occur in the area of a sea terrace and the Sergeijevfjellet Hill, the stratigraphic position of them is shown in Table 1.

2. Experimental 2.1. Description of samples This paper presents an insight into the characteristics of selected parameters, which determine the

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quality of coal as well as organic matter of coals and rocks. This preliminary research is a part of a large project investigating organic matter occurrence in Spitsbergen glacial deposits and meltwater. Since our preliminary investigation of glacial meltwater and rock debris indicated the presence of organic matter of various thermal maturity, samples of different age were compared to assess the possibility of migration of organic matter from coals and host rocks. The Tertiary coal samples from Central Basin (the Longyearbyen region, south shore of Isfjorden) and from the Forlandsundet Basin (Kaffioyra coastal plain, Oscar II Land) were investigated in this study (Fig. 1). The dispersed organic matter in the Mississippian and the Pennsylvanian rock samples from the Sorkapp Land was tested to compare with the organic matter of coal. Coal samples from Kaffioyra region (numbers 1 – 5), belonging to the Sarsbukta Member (Balanuspynten Formation, Buchananisen Group), were taken at the outcrop coal seam near the Aavatsmark Glacier. The details of a stratigraphic position of the Kaffioyra region coal samples are unknown, because they were sampled at the frontal part of the Aavatsmark Glacier valley, where direct observations were impossible. Coal samples from the Longyearbyen region (numbers 6 – 9) were taken in the Bear’s Valley from the outcrop coal seam, near a coal mine. They belong to the Firkanten Formation from the Longyearbyen seam of the Todalen Beds. The rocks samples from the Sorkapp Land (numbers 10 – 14) comprise sandstones, claystone, and spherosiderite. The sample number 10 is grey-brown finegrained sandstone with thin layers of coalified organic material. The sample number 11 is grey, fine-grained sandstone with thin layers of black claystone including imprints of Calamites on a surface. The sample number 12 is fine-grained and dark grey sandstone with irregular laminas of organic detritus including imprints of Calamites on a surface. The next (number 13) sample is brown-grey fine-grained not bedded sandstone with imprints of Stigmaria. The last sample (number 14) is dark brown spherosiderite with irregular thin veins of ankerite. Sample numbers 10, 13 and 14 were taken from the Suffolk Pynten area (Pallfyodden region) from the Hornsundneset Formation, while the samples 11 and 12 were collected from Sergeijevfjellet Hill from the Sergeijevfjellet Formation.

2.2. Analytical procedure Optical properties of coal and organic matter of rock samples were determined using a reflected light microscope. The technological value of coals according to the International Code System for Medium and High Rank Coals (ECE Geneva, 1988) as well as genetic properties according to the International Classification of Seam Coals (ECE Geneva, 1993) has been estimated. Petrologic analyses were carried out in reflected, white light. Analytical procedures used in microscopically studies followed ICCP standards. Vitrinite reflectance measurements for studied coals were determined using Zeiss-Opton microscopical-photometer system equipped with a 40  objective, 10  oculars, and 546-nm interference filters. The measurements of random collotelinite reflectance were carried out in nonpolarized reflected light and oil immersion with refractive index n = 1.5176 at T = 23 jC. The results were interpreted using the computerized system. Macerals were identified under the cross-point in the ocular for 500 points using an automatic point counter. Microlithotype analyses were carried out using a 20-point ocular and an automatic point counter. Magnification was the same as during maceral analysis. Microlithotypes were identified in 500 points covering the surface of the pellet. Geochemical analysis comprised solvent extraction of coals, chromatographic analysis of extract group composition and analysis of separated aliphatic and aromatic hydrocarbons by gas chromatography – mass spectrometry (GC-MS). The coal samples were cleaned of surface contamination using dichloromethane, powdered and extracted three times by a mixture of solvents: dichloromethane: ethanol (4:1 vol/vol) in a ultrasonic bath; each ultrasonification time was about 0.5 h. Extracts were separated into aliphatic, aromatic and polar compounds by preparative thin-layer chromatography (TLC). The 1% solutions of extracts (20 – 30 mg in CH2Cl2) were applied as bands onto the 20  20-cm glass plates precoated with silica gel (Kieselgel 60 F254, Merck) previously activated at 105 jC (35 min). Plates were developed in a TLC tank with n-hexane as a developer in saturated vapour conditions (development time about 40 min). The

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fractions were distinguished by the UV long-wave fluorescence of aliphatic (lack of fluorescence) and aromatic compounds (blue-violet) and by comparing Rf values of reference compounds (n-eicosane, phenanthrene and quinoline) developed on the same TLC plate. Group fractions were eluted from silica gel using dichloromethane (aliphatic and aromatic compounds) or the mixture of dichloromethane/ethanol (7:3 vol/vol) (polar compounds). Aliphatic and aromatic hydrocarbon fractions were analysed by GC-MS. An Agilent gas chromatograph with a HP-5 column (60 m  0.25 mm i.d.), coated by 0.25-Am stationary phase film coupled to a mass spectrometer was used. The experimental conditions were as follows: carrier gas, He; temperature program, 50 jC (isothermal for 2 min); heating rate to 175 jC at 10 jC/min, to 225 jC at 6 jC/min, and to 300 jC at 4 jC/min; final isothermal temperature: 300 jC was held for 20 min. The mass spectrometer was operated in the electron impact ionization mode at 70 eV and scanned from 50 to 650 Da. Data were acquired in a full-scan mode and processed with the Hewlett Packard Chemstation software. All compounds were identified by their mass spectra and comparison of retention times of their peaks to these of standard

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compounds and literature data and interpretation of MS fragmentation patterns. The objective of GC-MS analysis was to analyse both aliphatic and aromatic hydrocarbon fractions of extracts. Distribution of biomarkers, such as n-alkanes, diterpanes, steranes, tri- and pentacyclic triterpanes, and several groups of aromatic hydrocarbons and their aliphatic derivatives were investigated.

3. Petrographic and geochemical results 3.1. Coal and dispersed organic matter properties Characteristics of coals and the dispersed organic matter of rocks from the regions investigated included petrographic composition, optical, chemical and technological properties (C´miel, 1999). The average maceral composition of coals from both regions is similar; macerals of the vitrinite group are dominant (Table 2). They differ in the kind of contents of inertinite group macerals only. Among the coal samples from the Kaffioyra region, the large differences in petrographic composition were observed. The samples number 3, 4 and 5 contain more of vitrinite group macerals and

Table 2 Maceral composition and vitrinite reflectance of samples investigated (1 – 14 samples from the investigated regions, 1 – 5, 6 – 9, 10 – 14 average values for the particular groups of samples) Maceral (% vol.)/sample 1

2

3

Vitrinite group 88.2 74.1 78.1 Collotelinite 81.6 72.9 70.0 Telinite 6.6 1.2 8.1 Liptinite group 0.6 15.9 12.6 Sporinite 0.3 3.8 6.6 Cutinite 0.1 0.0 2.8 Resinite 0.2 12.1 3.2 Inertinite group 1.6 8.9 4.3 Fusinite 0.7 3.9 1.3 Semifusinite 0.7 3.8 1.3 Macrinite 0.2 0.3 0.9 Micrinite 0.0 0.9 0.5 Inertodetrinite 0.0 0.0 0.3 Mineral matter 9.6 1.1 5.0 Clay minerals 1.5 0.5 0.7 Carbonates 3.8 0.0 1.1 Pyrite 3.9 0.6 3.2 Quartz 0.4 0.0 0.0 Vitrinite reflectance (%) 0.59 0.65 0.67 Standard deviation 0.03 0.04 0.03

4

5

6

7

8

9

10

11

12

13

14

1 – 5 6 – 9 10 – 14

86.6 78.3 8.3 0.0 0.0 0.0 0.0 1.8 0.8 1.0 0.0 0.0 0.0 11.6 6.2 4.0 0.9 0.5 0.61 0.05

85.3 77.1 8.2 1.8 0.6 0.4 0.8 2.1 0.8 0.9 0.4 0.0 0.0 10.8 4.9 3.1 1.6 1.2 0.62 0.05

83.7 83.7 0.0 3.5 2.1 0.7 0.7 4.5 0.7 2.8 0.8 0.0 0.2 8.3 0.9 0.0 7.2 0.2 0.70 0.4

77.3 77.0 0.3 7.2 3.1 0.2 3.9 12.4 8.3 3.1 0.5 0.0 0.5 3.1 1.1 0.2 1.5 0.3 0.72 0.04

79.0 79.0 0.0 10.4 3.8 0.2 6.4 6.3 3.8 2.0 0.2 0.3 0.0 4.3 1.0 0.3 2.9 0.1 0.69 0.05

68.7 68.1 0.6 5.4 3.1 0.8 1.5 18.1 10.3 5.1 2.1 0.6 0.0 7.8 2.6 0.5 3.9 0.8 0.64 0.05

53.8 53.8 0.0 6.2 6.2 0.0 0.0 26.9 19.1 6.8 0.0 1.0 0.0 13.1 6.2 6.9 0.0 0.0 0.77 0.13

44.9 44.9 0.0 4.1 2.8 0.0 1.3 36.2 30.8 3.3 0.0 2.1 0.0 14.8 4.1 8.9 1.8 0.0 0.90 0.15

46.8 46.8 0.0 3.7 2.6 0.0 1.1 38.5 32.2 2.9 0.0 3.4 0.0 11.0 3.1 7.2 0.7 0.0 0.92 0.12

58.0 57.6 0.4 8.0 7.6 0.0 0.4 24.2 17.2 5.2 0.5 1.0 0.3 9.8 8.5 0.5 0.8 0.0 0.82 0.11

53.1 1.3 51.8 3.9 3.4 0.0 0.5 22.3 13.1 7.0 1.0 1.2 0.0 20.7 5.9 12.7 2.1 0.0 0.83 0.12

82.5 76.0 6.5 6.2 2.3 0.7 3.2 3.7 1.5 1.5 0.4 0.3 0.0 7.6 2.8 2.4 2.0 0.4 0.63 0.04

77.1 76.9 0.2 6.6 3.0 0.5 3.1 10.3 5.8 3.2 0.9 0.2 0.2 6.0 1.4 0.3 3.9 0.4 0.69 0.05

51.3 51.0 0.3 5.2 4.5 0.0 0.7 29.6 22.5 5.0 0.3 1.7 0.1 13.9 5.6 7.2 1.1 0.0 0.85 0.12

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The vitrinite group macerals, mostly collotelinite, are dominant in organic matter of rock samples. The second are inertinite group macerals, mostly fusinite and semifusinite; the next are liptinite group macerals, mainly sporinite. Carbonates and clay minerals are dominant in mineral matter. Samples 11 and 12 are different from the other Sorkapp Land samples. They contain less vitrinite and liptinite group macerals and more inertinite group macerals as well as similar quantity of mineral matter. The vitrinite reflectance of these samples is also higher. Among microlithotypes, vitrite and duroclarite contents are lower, inertite higher, while the content of carbominerite (mostly carbankerite) is higher in comparison with the other organic matter samples. The optical properties of coals from Longyearbyen and Kaffioyra are different from properties of dispersed organic matter of rocks from Sorkapp Land. Macerals of vitrinite group, mostly collotelinite, dominate in all of coal samples. The average content of vitrinite group macerals is much lower in dispersed organic matter than it is in coals. The average content of liptinite group macerals is a little lower, with dominant sporinite; the average content of inertinite group macerals is much higher, with dominant fusinite. The content of micrinite is much higher than in

mineral matter, much less inertinite group macerals, as well as insignificant quantity of liptinite group macerals. The average contents of microlitotypes, carbominerites and mineral matter in coals from both regions investigated are also similar (Table 3). The only distinct differences in contents of clarite, carbopyrite and carbonates were observed. Coals from the Longyearbyen region show an absence of carbankerite and carbopolyminerite. The samples number 1 and 2 from the Kaffioyra region contains much lower amounts of clarite and liptite but more mineral matter, carbonates, as well as clay minerals in comparison with samples number 3, 4 and 5. The values of vitrinite reflectance and standard deviation of coals investigated are similar (Table 2). The reflectograms of vitrinite reflectance for coals from both regions are continuous and slightly asymmetric (Fig. 2). Reflectograms of vitrinite reflectance of coals from Kaffioyra on the basis contains five of 1/ 2V steps in the range 0.55 –0.85% and maximum in the range of 0.55– 0.65% 1/2V step. The reflectograms of vitrinite reflectance coals from Longyearbyen show a maximum in the range of 0.60 – 0.75% 1/2V step. The basis of the reflectograms contains four or five of 1/2V step in the range of 0.50– 0.85%.

Table 3 Microlithotype composition of samples investigated (1 – 14 samples from the investigated regions, 1 – 5, 6 – 9, 10 – 14 average values for the particular groups of samples) Parameter/sample

1

2

3

Microlithotypes (% vol.) 84.7 84.0 80.2 Vitrite 54.6 43.8 68.8 Inertite 1.2 0.0 2.3 Liptite 1.3 1.4 1.0 Clarite 26.5 30.6 4.4 Vitrinertite 0.0 0.3 0.0 Duroclarite 0.5 4.4 2.8 Clarodurite 0.6 3.5 0.9 Vitrinertoliptite 0.0 0.0 0.0 Carbominerites (% vol.) 8.3 14.9 10.2 Carbopyrite 2.1 4.8 3.7 Carbankerite 5.4 0.0 5.6 Carbopoliminerite 0.8 0.0 0.9 Carbargilite 0.0 10.1 0.0 Mineral matter (% vol.) 7.0 1.1 9.6 Clay minerals 0.7 0.2 1.5 Carbonates 2.1 0.0 3.8 Pyrite 4.2 0.9 3.9 Quartz 0.0 0.0 0.4

4

5

6

7

8

82.1 61.1 1.0 0.0 17.6 1.0 0.8 0.6 0.0 12.6 3.5 0.0 3.7 5.4 5.3 2.1 1.8 1.4 0.0

80.7 54.3 2.1 0.5 14.4 6.3 0.5 2.6 0.0 10.0 1.7 1.0 0.0 7.3 9.3 3.4 3.8 2.1 0,0

72.9 52.4 0.8 0.0 11.1 4.0 4.6 0.0 0.0 18.8 18.8 0.0 0.0 0.0 8.3 0.7 0.0 7.2 0.4

82.2 45.8 1.6 0.5 32.6 0.5 1.2 0.0 0.0 10.0 8.6 0.0 0.0 1.4 7.8 2.6 0.5 3.9 0.8

85.0 90.6 81.0 76.5 69.0 82.5 40.6 36.0 38.2 31.6 34.8 41.2 3.5 5.0 5.8 8.0 4.1 4.8 0.0 0.0 0.9 0.9 1.1 1.4 33.9 42.9 0.0 2.2 0.0 0.0 0.5 0.5 5.1 6.1 3.7 7.1 3.8 3.5 12.6 10.9 15.0 16.8 2.7 1.7 18.4 16.8 10.3 11.2 0.0 1.0 0.0 0.0 0.0 0.0 10.7 6.3 10.5 13.5 15.1 11.5 7.1 1.2 0.5 4.3 2.1 2.8 0.0 0.0 4.6 7.2 9.5 2.6 0.0 0.0 0.4 0.0 0.0 0.5 3.6 5.1 5.0 2.0 3.5 5.6 4.3 3.1 8.5 10.0 15.9 6.0 1.0 1.1 4.8 3.9 5.2 4.9 0.3 0.2 2.7 5.0 9.5 0.5 2.9 1.5 1.0 1.1 1.2 0.6 0.1 0.3 0.0 0.0 0.0 0.0

9

10

11

12

13

14

1 – 5 6 – 9 10 – 14

85.4 45.6 3.0 0.5 0.0 5.0 19.3 12.0 0.0 9.4 3.4 0.4 0.0 5.6 5.2 3.4 0.0 1.3 0.5

82.3 56.5 1.3 0.9 18.7 1.5 1.8 1.6 0.0 11.2 3.2 2.4 1.1 4.5 6.5 1.6 2.3 2.5 0.1

82.7 43.7 2.7 0.1 30.1 1.4 3.3 1.1 0.3 11.4 8.9 0.0 0.0 2.5 5.9 1.3 0.3 3.9 0.4

78.9 38.3 5.1 1.0 0.5 5.4 14.9 13.7 0.0 12.0 2.6 4.9 0.2 4.3 9.1 4.4 3.5 1.1 0.1

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Fig. 2. Reflectograms of mean vitrinite reflectance of Kaffioyra coals (samples 1 – 5) and Longyearbyen coals (samples 6 – 9). (A) Vitrinite reflectance of investigated samples.

coal samples. The average content of mineral matter is higher in rock samples than in coal samples, with a dominance of carbonates and clay minerals. The average value of vitrinite reflectance and standard deviation of rock samples is higher in comparison with coals. The vitrite predominates in microlithotype composition of dispersed organic matter, but this average content is lower, similarly as content of clarite in comparison with coals investigated. However, on average, dispersed organic matter of rocks contains much more duroclarite and clarodurite. The content of carbominerites is similar for all samples, but carbominerites of dispersed organic matter contains more carbankerite. The rock samples contain more of mineral matter. Carbonates and clay minerals dominate in the mineral part of rock samples, whereas pyrite and clay minerals dominate in coals. The significant differences in the chemical and technological properties of coals from both regions were apparent (Table 4). The coalification degree is generally higher in coals from Longyearbyen. Those samples have slightly higher content of carbon, hydrogen, nitrogen, as well as higher calorific value and

vitrinite reflectance. The technological properties of them are better because of good coking properties and less content of ash. In the Longyearbyen region, the coal sample number 6 shows the best properties, despite the highest content of sulphur. There are clear differences between coal samples number 3, 4, 5 and 1 and 2 from the Kaffioyra region. Low calorific value, content of carbon, hydrogen, vitrinite reflectance value, lack of coking properties as well as higher contents of ash, moisture, oxygen and higher of volume density are indicative of the weathering change of the first group of Kaffioyra coal samples. For comparison, the Carboniferous coals of the Sorkapp Land region that are not coking have similar content of hydrogen (4– 5%) and ash (2– 30%), considerably higher content of carbon (81 – 88%) and vitrinite reflectance (1.41%), whereas content of moisture (1 –2%) and volatile matter (15 –23%) are considerably lower (Lipiarski and C´miel, 1984). The International Classification System for Medium and High Rank Coals (ECE Geneva, 1988) and the International Classification of Seam Coals (ECE Geneva, 1993) completely defined the technological

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Table 4 Chemical and technological parameters of coals investigated (1 – 9 samples from the investigation regions, 1 – 5, 6 – 9 average values for the particular group of samples) Parameter/sample

1

2

Ash (d) (%) 10.40 13.81 Moisture (%) 4.80 5.09 Volatile matter (daf) % 35.70 35.55 Calorific value (daf) (MJ/kg) 29.80 30.66 Carbon (daf) (%) 80.30 79.60 Hydrogen (daf) (%) 5.19 5.11 Hydrogen/carbon 0.065 0.053 Nitrogen (daf) (%) 1.60 1.82 Oxygen (daf) (%) 11.80 12.28 Sulphur (d) (%) 1.03 1.14 Coking capacity—Roga index 5.00 0.00 Free swelling index 1.00 1.00 Dilatation (%) 0.00 0.00 Contraction (%) 10.00 15.00 Softening temperature (jC) 345.00 355.00 Contraction temperature (jC) 380.00 385.00 Dilatation temperature (jC) 0.00 0.00 Volume density (Mg/m3) 1.38 1.36

3

4

5

9.60 5.30 34.1 31.30 76.27 4.64 0.061 2.83 15.10 1.16 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.42

20.60 9.30 33.60 26.30 71.20 4.10 0.058 2.60 21.59 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.58

21.60 8.22 7.12 7.93 9.44 15.21 8.13 8.70 7.06 6.03 6.54 5.42 6.64 6.26 32.10 41.07 35.63 37.60 32.83 34.20 36.78 27.10 35.70 32.41 31.82 30.16 29.03 32.52 73.80 81.61 83.05 82.60 81.00 76.23 82.06 3.90 5.21 5.32 5.67 5.70 4.59 5.47 0.053 0.064 0.064 0.069 0.070 0.058 0.068 2.40 1.35 1.75 1.12 1.85 2.25 1.52 19.32 7.53 8.58 7.46 10.59 16.02 8.54 0.52 3.64 1.22 2.47 0.81 0.86 2.03 0.00 80.00 45.00 25.00 5.00 1.00 38.75 0.00 8.50 3.00 3.00 2.00 0.40 4.12 0.00 53.00 35.00 15.00 0.00 0.00 25.75 0.00 34.00 20.00 10.00 15.00 5.00 19.75 0.00 325.00 330.00 335.00 340.00 140.00 332.50 0.00 405.00 395.00 390.00 385.00 153.00 193.75 0.00 440.00 420.00 410.00 0.00 0.00 317.50 1.52 1.31 1.37 1.35 1.42 1.45 1.36

properties of examined coals. The technological classification is based on petrographic composition, optical, chemical and technological properties. In this classification, each coal sample has a 14-digit code number, based on the values of the vitrinite reflectance, its standard deviation and reflectogram, on the petrographic composition, and chemical and technological properties. The code numbers of coals samples examined are shown in Table 5. The International Classification of Seam Coals has a genetic character, and it is based on parameters defining the coalification degree, the petrographic composition and degree of mineral matter impurity. All investigated coal samples are humic (banded) Table 5 Code number of coals investigated in accordance with International Classification System for Medium and High Rank Coals (ECE Geneva, 1988) Sample

Code number

1 2 3 4 5 6 7 8 9

06 06 05 06 06 07 07 06 06

00 00 00 00 00 00 01 00 01

3 4 1 0 1 0 2 3 2

1 1 0 0 0 8 3 3 2

34 34 34 32 32 40 34 36 32

10 13 09 20 21 08 07 07 09

10 11 11 04 05 38 12 24 08

29 30 31 26 27 35 32 31 30

6

7

8

9

1–5

6–9

coals with high vitrinite content. Sample number 1 can be classified as parabituminous, medium rank type D; the others samples of coal are classified as orthobituminous, medium rank type C. Samples number 3, 6, 7, 8 and 9 are very low-grade coal, samples 1 and 2 are low-grade coal, while samples 4 and 5 are middle-grade coal. 3.2. Geochemical characteristics of coals and dispersed organic matter Several groups of aliphatic biomarkers and aromatic hydrocarbons were identified in the extracts of coals, sandstones, spherosiderite and calamites. In the coal extracts, biomarkers are usually present in relatively high concentrations, and GC-MS distributions are well defined, while both sandstone extracts is rather poor in biomarkers, and composition of aliphatic hydrocarbon fraction is dominated by nalkanes. In the Kaffioyra 1, 2, 4 and 5 coal extracts, n-alkanes are absent or present in very low amounts, which is a feature uncommon in coals. Only the sample 2 coal extract contains short-chain n-alkanes up to n-nonadecane. Aliphatic hydrocarbon fractions of these coals are composed almost entirely of sesquiterpanes. Sesquiterpanes are also present in the samples 6 and 8 extracts but in much lower concentration.

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n-Alkanes in the samples number 3, 11, 12 and 14 (coal, both calamites and spherosiderite) extracts show a bimodal distribution with maximums at nC14 –n-C15 and n-C23 – n-C25, while the samples number 6, 10 and 13 extracts are characterised by unimodal distribution with maximums at n-C17 – n-C18 and n-C23 – n-C25, respectively (Fig. 3). Short-chain n-

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alkanes dominate over long-chain n-alkanes in the samples number 1 –5, 10, 13 and 14 extracts (S1/S2 parameter in Table 6). Only slight odd-over-even predominance for n-alkanes in the range n-C24 –nC33 indicates that the samples 7 and 9 coals are of higher rank than the sample 3 coal in which extract this predominance is much better developed. This

Fig. 3. Distribution of aliphatic hydrocarbons in the extracts of the Longyearbyen coals (6 and 9), the Kaffioyra coal (3) and dispersed organic matter (11, 10).

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Sample

1 2 3 4 5 6 7 8 9 10 11 12 13 14

S1/S2

Pr/Ph

Pr/n-C17

Pr/n-C18

(1)

(2)

(3)

(4)

(5)

(6)

3.8 2.5 – – – 1.8 12.0 2.0 2.4 1.8 1.1 1.3 1.0 1.9

3.2 1.6 – – – 0.9 96.0 1.4 0.6 0.3 1.2 0.9 0.2 0.1

1.0 0.9 – – – 0.5 2.6 0.8 0.3 0.4 0.8 0.7 0.2 0.1

1.83 – – – – 2.67 0.44 4.28 5.02 4.61 1.18 2.53 5.33 7.98

3.5 – – – – 2.0 1.4 4.2 1.3 1.1 1.1 1.2 1.0 1.0

28 34 36 – 35 32 – 34 26 – 12 13 11 8

CPI

C30ha/ (ah + ha)

C31ah 22S/(22S + 20R)

C29aaa 20S/(20S + 20R)

(7)

(8)

16 23 – – 33 7 – 5 5 – – – – –

27 22 37 – 29 44 – 32 51 58 59 57 59 60

C30hh/(ah + ha + hh)

MNR

DNR-2

TNR-2

MPI-3

DMPR

(9)

(10)

(11)

(12)

(13)

(14)

4 – – – – – 42 – 18 – 51 – 49 55

1.39 2.23 1.37 1.80 2.16 0.88 – 1.39 0.98 0.86 1.45 1.28 – 1.57

3.00 2.86 1.93 2.86 2.90 0.95 0.08 2.38 0.99 4.17 3.41 5.14 – 4.67

0.59 0.58 0.57 0.63 0.59 0.55 0.67 0.73 0.71 1.06 0.52 0.63 – 0.70

0.79 0.85 0.61 0.94 0.94 1.03 0.96 0.69 0.88 0.46 3.49 3.38 1.84 1.98

0.36 0.22 0.28 0.17 0.26 0.20 0.36 0.18 0.75 0.46 1.17 1.20 0.89 0.69

(1) Pr/Ph = pristane/phytane; parameter of environment oxity (with exception of coals). (2) Pr/n-C17 = pristane/n-heptadecane. (3) Ph/n-C18 = pristane/n-octadecane. (4) S1/S2=[S (from n-C13 to n-C22)]/[S (from n-C23 to n-C35)]; (source indicator). (5) CPI = 1/2{[(n-C25 + n-C27 + n-C29 + n-C31 + n-C33)/(n-C24 + n-C26 + n-C28 + n-C30 + n-C32)]+[(n-C25 + n-C27 + n-C29 + n-C31 + n-C33)/(n-C26 + n-C28 + n-C30 + n-C32 + n-C34)]; carbon preference index; thermal maturity parameter. (6) C30 ha/(ha + ah) = 17h(H),21a(H)-hopane/ (17h(H),21a(H)-hopane + 17a(H),21h(H)-hopane). (7) C30 hh/(ha + ah + hh) = 17h(H),21a(H)-hopane/(17h(H),21a(H)-hopane + 17a(H),21h(H)-hopane + 17h(H),21h(H)hopane). (8) C31ah22S/(22S + 22R) = 17a(H),21h(H)-29-homohopane 22S/(17a(H),21h(H)-29-homohopane 22S + 17a(H),21h(H)-29-homohopane 22R). (9) C29aaa20S/(20S+ 20R) = 5a(H),14a(H),17a(H) C29 sterane 20S/(5a(H),14a(H),17a(H)C29 sterane 20S + 5a(H),14a(H),17a(H) C29 sterane 20R). (10) MNR = 2-methylnaphthalene/1-methylnaphthalene; methylnaphthalene ratio. (11) DNR-2=(2,6-DNM + 2,7-DMN)/1,5-DMN; dimethylnaphthalene ratio. (12) Rcalc 1 = 0.49 + 0.09 DNR-2; calculated vitrinite reflectance; thermal maturity parameter. (13) MPI-3=(2-MP + 3-MP)/(1-MP + 9-MP); methylphenanthrene index. (14) DMPR=(2,6-DMP + 3,5-DMP + 2,7-DMP)/(1,3-DMP + 3,9-DMP + 3,10DMP + 2,9-DMP + 2,10-DMP + 1,6-DMP + 2,5-DMP); dimethylphenanthrene ratio.

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Table 6 Geochemical parameters calculated for extracts of coals and rocks organic matter of samples investigated

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feature is reflected by the values of Carbon Preference Index: 1.4 and 1.3 for the samples 7 and 9 coals, respectively, and 3.5 for the sample 3 coal (Bray and Evans, 1961). Values of CPI for spherosiderite, calamites and sandstones are close to 1.0. The samples 6 and 8 coal extracts show much higher CPI values: 2.0 and 4.2, respectively. Odd-over-even predominance in the range of long-chain n-alkanes (n-C24 –n-C33) is a feature inherited directly from fatty acids occurring in cuticular waxes of vascular plants. It tends to decrease with increasing thermal maturity of organic matter. Very low concentration of short-chain n-alkanes and the characteristic ‘‘cut’’ envelope of n-alkane distribution in that range, high values of Pr/n-C17 and very

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low concentration of lighter aromatic hydrocarbons in extracts can indicate extensive water washing of organic matter in the case of the sample 7 coal (Palmer, 1984). All extracts contain large amounts of acyclic isoprenoids: especially pristane and several shorter compounds of this group. The exception here is the rock sample 14 extract, which contains only very low content of these compounds. Phytane is generally present in the lower concentration than pristane and Pr/Ph values are in the range from 1.0 (rock sample 13) to 12.0 (coal sample 6). The high values of the parameter do not indicate highly oxic depositional environment in the case of coals but rather

Fig. 4. Identification of (a) acyclic isoprenoids in the sample 6 coal extract (m/z = 71). (b) Bicyclic sesquiterpanes in the sample 4 coal.

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high input of vascular plant material in organic matter (ten Haven et al., 1987). In the case of the sandstones (rock samples 10 and 13), the value of Pr/Ph slightly higher than 1.0 (1.2 and 1.8) suggests rather oxic environment of deposition and can be assumed to be valid (Didyk et al., 1978). A series of shorter acyclic isoprenoids tentatively identified as 2,6,10-trimethylpentadecane, 4,11-dimethyltetradecane, 2,6,10-trimethyldodecane, 7-methyltridecane in the sample 6 coal extract probably comes from pristane cracking (Fig. 4a). The unique feature of samples 1, 2, 4 and 5 coal extracts are large amounts of bicyclic sesquiterpanes, especially 8h(H)-drimane, found in their aliphatic hydrocarbon fractions (Fig. 4b). Their presence caused so low concentrations of all other compounds

that biomarker interpretation is impossible in most of the cases. Only low amounts of diterpanes and pentacyclic triterpanes were found and identified by comparison of their retention times. The sesquiterpane distribution contains two saturated C14 compounds, a saturated C15 compounds identified as 8h(H)-drimane and several unsaturated C15 compounds. The C16 sesquiterpanes such as 8h(H)-homodrimane were not found. The tricyclic (m/z = 123) and tetracyclic diterpanes (m/z = 274) were found in the extracts. The sample 1 extract of the Kaffioyra coals contains both 16a(H)and 16h(H)-phyllocladanes (the Podocarpaceae family indicators; Noble et al., 1985, 1986; Disnar and Harouna, 1994) in relatively high concentrations (seen at m/z = 274 or 259) and two tricyclic diterpanes,

Fig. 5. Distribution of diterpanes found in (a) the Kaffioyra coal (3) and (b) the Longyearbyen coal (6).

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norisopimarane and norpimarane. The samples 1, 2 and 5 contain only both phyllocladanes and norisopimarane. Among other tetracyclic diterpanes only 16h(H)-kaurane (the Araucariceae family indicator) and ent-beyerane were found in the sample 3 coal in

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the amounts enabling their identification by mass spectra (Fig. 5). The samples 7 and 8 coal extracts show the distribution of tricyclic and tetracyclic diterpanes similar to the samples 1– 5 coals while the sample 9 coal extract is rich in norisopimarane,

Fig. 6. Distribution of pentacyclic triterpanes in the extracts of the Longyearbyen coals (6 and 9), the Kaffioyra coal (3), dispersed organic matter (14, 13).

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norpimarane and isopimarane and relatively poor in phyllocladanes. The sample 6 coal extract does not contain tetracyclic diterpanes except very low amounts of ent-beyerane, but there are tricyclic diterpanes such as isopimarane, norpimarane, and noriso-

pimarane in the samples 1 –5 coal extract (Fig. 5). The calamite extract 11 contains only very low amount of 16a(H)-phyllocladane, and the sample 12 extract does not contain them at all. The sample 10 and 13 sandstone extracts do not contain any diterpanes. This

Fig. 7. Distribution of steranes found in the Longyearbyen coals (6 and 9), Kaffioyra coal (3), dispersed organic matter (14, 10).

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excludes participation of vascular plants in formation of their kerogen and confirms the same conclusion basing on n-alkane distribution. Among identified tricyclic triterpanes, isocopalane is shown in Fig. 5 (Philp, 1985). The coal extracts contain well-developed distributions of pentacyclic triterpanes (hopanes and moretanes) shown in Fig. 6. Their distribution is composed of hopanes in the range from C 29 to C 34 (from 17a,21h(H)-30-norhopane to 17a,21h(H)-29-tetrakishomohopane), moretanes in the range from C29 to C32 (from 17h,21a(H)-30-normoretane to 17h,21a(H)29-bishomohopane) and 17h,21h(H)-hopane found in significant amounts in the extracts of the Kaffoyra coals. The hopane distributions in the dipersed organic matter extracts do not show hh hopanes indicating

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higher maturity reflected by maturity parameters (Table 6). The samples 10 and 13 rock extracts contain small amounts of hopanes. Because of the very low quality of spectra, the identification of them was done only by their retention times. A series of tricyclic tritepanes present in low concentration can be seen in the same ion chromatogram together with sesquiterpanes. Oleananes were not present in all extracts indicating that there was not a significant angiosperm input into organic matter (Ekweozor and Udo, 1988; Moldowan, 1994). Steranes are generally in low concentration in coal extracts where their distribution is dominated by C29 isomers (stigmastanes being diagenetic products of sitosterol) such distribution is related to the dominating vascular plant source of organic matter (Fig. 7)

Fig. 8. (a) Products of abietic acid aromatisation, (b) cuparene, the product of a-cedrene aromatisation found in the samples 1 – 5 coal extracts.

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(Huang and Meinschein, 1979). The samples 1, 2, 4 and 5 coal extracts do not contain steranes. It was difficult to identify steranes in the samples 10 and 13 sandstone extracts, but there are four peaks of compounds, for which retention times indicate that they also belong to C29 steranes. Triaromatic steroids occur in both coals, but they were not found in the sample 10 sandstone extract. Aromatic hydrocarbon distributions are different in the sample extracts. All extracts of coals, except the sample 9 coal extract, show the distribution dominated by retene (derived from abietic acid) and a series of C5 alkyl decahydronaphthalenes (m/z = 208) (Fig. 8). A series of abietane aromatisation products are also present, among them, simonellite and dehydroabietane were identified. Polyaromatic hydrocarbons containing more than three condensed rings in a molecule are very minor components in these extracts. The relatively high concentration of cuparene in the samples 1 –5 coal extracts was found at m/z = 132 (Fig. 8a), the compound being the diagenetic product of acedrene and cedrol aromatisation. Its presence indicates major input of Cupressaceae and Taxodiaceae families to primary organic material of the samples 1 – 5 coal (Lu and Kaplan, 1992). It is worth mentioning that the samples containing cuparene contain also

large amounts of bicyclic sesquiterpanes in their aliphatic hydrocarbon fractions. It may be assumed that both cedrene products and sesquiterpanes are source-related to each other. a-Cedrene products do not occur in the samples 6 and 7 coal extracts and samples 10– 14 stones extracts. Cadalene is present in samples 1– 5 and 7 – 8 coals in significant amounts, but intermediate products of cadinane aromatisation were found only in very low amounts (cadinatrienes) or were not found at all (calamenenes) (van Aarssen et al., 1990). In addition, C3 tetrahydronaphthalenes comprise a significant part of naphthalene derivatives found in the aromatic hydrocarbon fractions of these coals. Polyaromatic hydrocarbons (PAHs) composed of more than three condensed aromatic rings do not occur in samples 1– 5 and 7 – 8 coals. Phenanthrene and methylphenanthrenes dominate among aromatic hydrocarbons of the samples 10– 14 rock extracts (Fig. 9). Distributions of dimethylphenathrenes and alkyl naphthalenes are also well developed except the sample 13 rock extract which shows features indicating water washing of the lighter aromatic hydrocarbons. Polycyclic aromatic hydrocarbons (PAHs) of higher condensation (four to five rings) are present in higher concentrations in these samples than it was in the case of coal extracts. Alkyl

Fig. 9. Distribution of alkylphenanthrenes identified in the sample 10 rock extract.

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derivatives of PAHs such as methylbenzanthracenes, methylchrysenes (m/z = 242), dimethylbenzanthracenes (m/z = 256) and methylperylenes (m/z = 266) were identified. The sample 1 coal contains only dimethylbenz[c]phenanthrene and the sample 7 coal dimethylbenz[c]phenanthrene in higher concentration and methylchrysenes. The sample 9 coal aromatic hydrocarbon distribution seems to be more similar to that of samples of higher thermal maturity (samples 10 – 14) than to the other coal extracts. It contains only low amounts of cadalene; retene is absent here, while polycyclic aromatic hydrocarbons are present in significant concentrations. Both the samples 6 and 9 coal extract are rich in alkyl derivatives of polycyclic aromatic hydrocarbons, for example, 5,8-dimethyl-benzo[c]phenannthrene. In addition, only partially aromatised highmolecular-weight hydrocarbons were found, such as 2,2,9-trimethyl-1,2,3,4-tetrahydro-picene (a compound with the highest concentration in the sample 6). Among others, 4V-phenyl-1,1V:2V,1U-terphenyl was identified. All samples contain alkyl naphthalenes from methylnaphthalenes (m/z = 142) tetramethylnaphthalenes (m/z = 184) except the sample 13 rock extract where these compounds are absent. Alkyl naphthalenes were applied to estimate thermal maturity of the samples

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organic matter (Radke, 1987; Radke et al., 1994) (Fig. 10). In the case of the samples 1 – 5 coals, alkyl naphthalenes show concentrations decreasing from methylnaphthalenes to tetramethylnaphthalenes. For the samples 7 and 8 coal extracts, dimethyl- and trimethylnaphthalenes occur in the highest content, while the samples 11, 12, 14 and 9 extract show naphthalene distribution dominated by trimethylnaphthalenes with very low amounts of methylnaphthalenes.

4. Discussion of results 4.1. The depositional environmental of the coals and dispersed organic matter The examination of optical properties of coals and dispersed organic matter indicates that there are similarities and differences between them. The mode of formation of investigated samples is similar. Coals and dispersed organic matter were formed in basins with rapid subsidence, high moisture and low pH. The organic matter of these basins was formed from vascular plants in a wet forest swamp. The decomposition of cellulose and lignin from plants occurred in anaerobic conditions with generally high but variable water level. This is confirmed by the dominance of

Fig. 10. Distribution of alkylnaphthalenes identified in the sample 3 coal extract.

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vitrinite group macerals (mostly collotelinite), and vitrite, clarite, duruclarite and clarodurite among microlithotypes confirms it. The extent of water level changes as well as of weathering and conflagrations periods of mires were variable. This variability is best reflected by the variability in the contents of macerals of the inertinite group (mostly fusinite, semifusinite and micrinite) comparing the coals from the particular region. The largest changes in water level took place when the dispersed organic matter of the Pennsylvanian Sergeijevfjellet Formation was formed. The dispersed organic matter of this formation contains the highest amounts of fusinite and micrinite of all samples. Fusinite was formed from tissue bark of Calamites (there are Calamites fossils in the samples 11 and 12). Micrinite was formed by decomposition of bituminite. The remaining part of bituminite was changed into resinite secondary. The weathering changes in other basins were not so intense, which is testified by the absence or the small amount of micrinite, with higher content of resinite. 4.2. The biological source of organic matter in the coals and rocks In the case of all Tertiary coals, the dominant organic matter source was terrestrial vascular plants. The typical features of geochemical composition indicate a high concentration of stigmastane isomer (C29) in a sterane distribution, domination of longchain n-alkanes and predomination of odd-over-even carbon number n-alkanes expressed by CPI values (Table 6). Tri- and tetracyclic diterpanes and abundant products of their aromatisation present in the extracts (retene, simonellite, tetrahydroretene) indicate conifers as a main group of land plants participating in coals formation. It seems that the main source of organic matter for the 1 – 5 and 6, 8 coal samples were various conifers with domination of Cupressaceae and Taxodiaceae families (a-cedrene products) and to a lesser extent also Podocarpaceae family (phyllocladanes), while primary organic matter of the 9 coal sample predominantly comes from Podocarpaceae conifers since only phyllocladanes are present in their diterpane distribution. The main source of the 7 coal sample are unidentified conifers, with possible small input of the Pinaceae family since isopimarane and norpimarane are present in this

sample (Otto and Simoneit, 2001). Oleananes were not present in the coal extracts indicating that angiosperms did not participate in the formation of organic matter in significant amounts (Ekweozor and Udo, 1988; Moldowan, 1994). Both series of Kaffioyra and Longyearbyen coals contain anthracene and 2-methylanthracene (seen at m/z = 178 and 192 ion chromatograms, respectively). In particular, the 6 and 9 coal samples extracts are rich in these substances. Their occurrence may indicate natural combustion during swamp fires since these compounds do not form from natural precursors and are products of combustion or pyrolytical processes (Simoneit, 1998). The content of fusinite, relatively highest in the coal group (8.3% and 10.3%, respectively) confirms the assumption that their presence is related to swamp fires. Despite the 10 – 14 sample content of fusinite, extracts do not contain these compounds. The origin of both 10 and 13 samples sandstone organic matter is different from that in the coals and much more difficult to interpret due to low concentration of these groups of biomarkers, which are often applied to this task, such as steranes or triaromatic steroids. However, it is possible to draw the following conclusions from the mass chromatograms. Distribution of n-alkanes indicates algal origin of organic matter deposited in the suboxic depositional environment since the envelope of distribution is similar to that shown by crude oils expelled from type I kerogen (Cooper, 1990; Peters and Moldowan, 1993). The absence of diterpanes in the extracts and the smooth envelope of n-alkane distribution exclude terrestrial origin or may indicate only very low terrestrial input into primary organic matter of sandstones. Sterane distribution suggests the algal origin of its organic matter due to higher concentration of the C27 sterane diasteromers (cholestenes) (Huang and Meinschein, 1979). The marine origin predominance is much well seen in the 10 samples where only cholestanes were found in the sterane distribution. The bimodal distribution of n-alkanes in the 11 sample extract with slight odd-over-even carbon-number predominance may suggest a mixed origin of this dispersed organic matter—marine with input of vascular plants. The sterane distribution of the 11 sample extracts is dominated by C27 sterane diastereomers (cholestenes), indicating algal components in its pri-

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mary organic matter. The 12 rock sample contains only low amounts of steranes and triaromatic steroids, but its sterane distribution is similar to that of the 11 sample. Diterpanes and their aromatisation products were not found in the 11 and 12 samples extracts. The origin of the 14 organic matter sample is probably similar to that of the 11 – 12 samples. Cholestane distereomers (C27) occur in the highest concentration in the sterane group suggesting the algal input. The smooth envelope of n-alkane distribution with the maximum of concentration at n-octadecane is characteristic for the I type kerogens of marine origin. Diterpanes and their aromatisation products are absent in this extract. 4.3. Coal rank assessment Rank of the Tertiary coals and organic matter dispersed in the rocks of the region were assessed using the values of thermal maturity parameters based on biomarkers. Both aliphatic and aromatic hydrocarbon ratios were applied to this aim. Their values are shown in Table 6, together with other maturity and source/environment parameters (Peters and Moldowan, 1993). The most complete data are for the 3 and 9 coal samples. The typical distributions of alkylphenanthrenes used in the calculation are shown in Fig. 9 and alkylnaphthalenes in Fig. 10. Coals from the Longyearbyen and Kaffioyra regions are slightly different in petrographical composition and coalification degree. The petrographic differences can result from variability of depositional conditions in the Central and Forlandsundet Basins. The properties of coal samples from the Longyearbyen region show an overall similarity, indicating similar conditions of deposition in a sedimentary basin. In some respects, this coal has the best technological and chemical parameters, as well as good coking properties, but the sulphur content is the highest of all samples. There are the distinct differences among coals from the Kaffioyra region. The unaltered properties of these coals are presented by number 1 and 2 samples. They indicate that these coals formed in typical depositional conditions of a wet forest swamp, as suggested by the highest content of vitrinite group macerals and the lowest content of inertinite group macerals. The highest content of liptinite group macerals indicates the

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abundance of resins and essential oils from vascular plants. The lower content of mineral matter indicates quiet sedimentation. Comparing samples number 3, 4 and 5 with samples number 1 and 2, significant differences in technological and chemical properties as well as petrological composition were found. The first group of samples contains more vitrinite group macerals and mineral matter, as well as less of inertinite group macerals and no liptinite group macerals. Besides, these coal samples contain more ash, moisture, oxygen, nitrogen and show higher volume density; however, they contain less of carbon, hydrogen and sulphur, and they show lower calorific value, lacking coking properties. These factors, as well as the small decrease of volatile matter content and the small increase of vitrinite reflectance, point to the influence of oxidation processes. The high degree of weathering of these coals is confirmed by the absence of nalkanes in their extracts (Fig. 3). The analysed coals of the Kaffioyra and Longyearbyen regions show similar values of thermal maturity parameters, indicating coal rank corresponding to the end of diagenesis to the beginning of catagenesis. These values generally correspond to the vitrinite reflectance values measured for the coals (0.59 – 0.70). Hopane-based parameters, the CPI value and Ro seem to indicate slightly higher rank for 9 coal sample, but this finding is not confirmed by the values of DNR-2 (dimethylnaphthalene ratio) and MPI-3 (methylphenanthrene index), the most valid parameters among these based on aromatic hydrocarbons. However, the DMPR (dimethylphenanthrene ratio) value seems to indicate much higher thermal maturity than those found for the other coals. Among the Longyearbyen coals, the 8 sample is of the lowest rank according to biomarker parameter. The samples 7 and 9 coal extracts show features indicating water washing of its organic matter such as very low concentration of lighter aromatic hydrocarbons (mainly methylnaphthalenes and dimethylnaphthalenes) and lighter aliphatic hydrocarbons (n-C 15 – n-C 20 n-alkanes which is reflected by the value of S1/S2 parameter in Table 6). As a result of water washing, the parameters valid for all samples are those which are based on compounds with higher molecular weight. Among these are hopane-based parameters and TNR-2, MPI-3 and DMPR (Radke et al., 1986; Radke, 1987; Radke et al., 1994).

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The Carboniferous dispersed organic matter coalification degree is higher than in Paleogene coals, which agrees with the coalification rule. However, a higher coalification degree of organic matter of the Sergeijevfjellet Formation than the dispersed organic matter from the Hornsundneset Formation can be related to dissimilarity of the evolution of basin environments. Among these samples, 14 and 12 seem to be of the highest rank. It was difficult to assess the maturity of the 13 sample due to water washing of its organic matter, which removed all alkylnaphthalenes. However, it was possible to calculate the MPI-3 and DMPR values which indicate thermal maturity similar to that of the 14 sample. Such rank is confirmed by the CPI value equal 1.0, C29 aaa 20S/(20S + 20R) sterane ratio near 49% and hopane parameters. The calculated values agree with the measured values of vitrinite reflectance (Ro) being in the range of 0.77 – 0.92 (Table 2).

5. Conclusions The analysis of Spitsbergen coals of Paleogene age and organic matter of the Carboniferous rocks shows that they were formed in basins with similar conditions. However, differences between them result from their stratigraphic position. Some differences are shown between dispersed organic matter of the Hornsundneset and the Sergeijevfjellet Formations. The organic matter of the Sergeijevfjellet Formation was formed in basins with higher fluctuation of water level, lower amount of water causing oxidation of organic matter in the basin. The mire plants contained less of resins and essential oils than the Hornsundneset Formation mire plants. The deposits of organic matter in a Tertiary basin were formed with faster subsidence and higher water level. In all Tertiary coals, the dominant organic matter source are terrestrial vascular plant remains. It seems that the main source of Kaffioyra coals and Longyearbyen coal samples were various conifers with domination of Cupressaceae and Taxodiaceae families and, to a lesser extent also, the Podocarpaceae family. Only the sample 9 coal organic matter predominantly comes from Podocarpaceae conifers. The main source of the 7 coal sample are unidenti-

fied conifers, with possible small input of the Pinaceae family. The plants of Oligocene age (Kaffioyra region) contain more resins and essential oils than plants of Paleocene age (Longyearbyen region), while coalification degree is similar. However, technological parameters of Paleocene coals are better. The organic matter of Kaffioyra region was formed in basins with higher fluctuation of water level than from the Longyearbyen region. Coals samples number 3, 4 and 5 (from Kaffioyra region) show of intense oxidation features caused by weathering. It may be assumed that the samples 10 and 13 dispersed organic matter is of algal origin deposited in the suboxic depositional environment, while the 11 and 12 sample organic mater is of a mixed origin—marine with a low input of vascular plants. The analysed coals of the Kaffioyra and Longyearbyen regions show similar values of thermal maturity parameters indicating coal rank corresponding to the end of diagenesis/beginning of catagenesis. The Carboniferous rocks organic matter coalification degree is higher than in Paleogene coals, which agrees with the coalification rule. However, a higher coalification degree of organic matter of the Sergeijevfjellet Formation than the dispersed organic matter from the Hornsundneset Formation can be related to dissimilarity of the evolution of basin environments.

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