petrological, organic geochemical and geochemical characteristics of coal from the soko mine, serbia

Available online at www.sciencedirect.com

eology 73 (2008) 285–306www.elsevier.com/locate/ijcoalgeo

International Journal of Coal G

Petrological, organic geochemical and geochemical characteristics ofcoal from the Soko mine, Serbia

Dragana Životić a,⁎, Herman Wehner b, Olga Cvetković c, Branimir Jovančićević c,d,Ivan Gržetić d, Georg Scheeder b, Angelika Vidal b, Aleksandra Šajnović c,

Marko Ercegovac e, Vladimir Simić a

a Faculty of Mining and Geology, University of Belgrade, Djušina 7, 11000 Belgrade, Serbiab Bundesanstalt für Geowissenschaften und Rohstoffe, Stilleweg 2, 30655 Hannover, Germany

c Center of Chemistry, IChTM, Studentski trg 16, 11000 Belgrade, Serbiad Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia

e Serbian Academy of Sciences and Arts, Knez Mihailova 35,11000 Belgrade, Serbia

Received 5 March 2007; received in revised form 10 June 2007; accepted 15 July 2007Available online 27 July 2007

Abstract

A petrological, organic geochemical and geochemical study was performed on coal samples from the Soko Mine, Soko Banjabasin, Serbia. Ten coal and two carbonaceous clay samples were collected from fresh, working faces in the underground browncoal mine from different parts of the main coal seam. The Lower Miocene, low-rank coal of the Soko Mine is a typical humic coalwith huminite concentrations of up to 76.2 vol.%, liptinite less than 14 vol.% and inertinite less than 11 vol.%. Ulminite is the mostabundant maceral with variable amounts of densinite and clay minerals. Sporinite and resinite are the most common macerals of theliptinite group. Inertodetrinite is the most abundant maceral of the inertinite group. The mineral-bituminous groundmass identifiedin some coal samples, and carbonaceous marly clay, indicate sub-aquatic origin and strong bacterial decomposition. The meanrandom huminite reflectance (ulminite B) for the main coal seam is 0.40±0.05% Rr, which is typical for an immature to earlymature stage of organic matter.

The extract yields from the coal of the Soko Banja basin ranges from 9413 to 14,096 ppm, in which alkanes constituted 1.0–20.1%, aromatics 1.3–14.7%, asphaltenes 28.1–76.2% and resins 20.2–43.5%. The saturated hydrocarbon fractions included n-C15 to n-C32, with an odd carbon number that predominate in almost all the samples. The contents of n-C27 and n-C29 alkanes areextremely high in some samples, as a contribution of epicuticular waxes from higher plants. Acyclic isoprenoid hydrocarbons areminor constituents in the aliphatic fraction, and the pristane/phytane (Pr/Ph) ratio varies between 0.56 and 3.13, which impliesanaerobic to oxic conditions during sedimentation. The most abundant diterpanes were abietane, dehydroabietane and 16α(H)-phyllocladane. In samples from the upper part of the coal seam, diterpanes are the dominant constituents of the alkane fraction.Polycyclic alkanes of the triterpane type are important constituents of alkane fractions. The occurrence of ββ- and αβ-typehopanes from C27 to C31, but without C28, is typical for the Soko Banja coals.

The major and trace elements in the coal were analysed using X-ray fluorescence (XRF), and inductively coupled plasma-massspectrometry (ICP-MS). In comparison with world lignites, using the geometric mean value, the coal from the Soko Banja Basinhas a high content of strontium (306.953 mg/kg). Higher values than the world lignites were obtained for Mo (3.614 mg/kg), Ni

⁎ Corresponding author.E-mail address: [email protected] (D. Životić).

0166-5162/$ - see front matter © 2007 Elsevier B.V. All rights reserved.doi:10.1016/j.coal.2007.07.001

mailto:[email protected]

http://dx.doi.org/10.1016/j.coal.2007.07.001

286 D. Životić et al. / International Journal of Coal Geology 73 (2008) 285–306

(8.119 mg/kg), Se (0.884 mg/kg), U (2.642 mg/kg) and W (0.148 mg/kg). Correlation analysis shows inorganic affinity for almostall the major and trace elements, except for S, which has an organic affinity.© 2007 Elsevier B.V. All rights reserved.

Keywords: Soko Banja basin; Coal petrography; Biomarker; Trace element; Lower Miocene

1. Introduction

Serbian low-rank coals represent the country's majorenergy source and have relatively large geologicalresources and reserves (99.6% of total reserves andresources). Previous investigations of Serbian low-rankcoals were focused mostly on the chemical properties(proximate, ultimate analysis). Coal petrological, paly-nological and paleobotanical investigations were per-formed on a rather small number of samples; bothorganic and inorganic geochemical studies are even lesscommon.

The intermontane Soko Banja coal basin is located250 km south-east of Belgrade (Fig. 1), and coversabout 250 km2. The Soko Banja basin is a north-southelongated tectonic depression with a maximum lengthof 29 km and width of 16 km. The basin is filled by upto 1500m thick limnic sediments, which accumulatedduring the time interval from the lower Palaeogene tothe upper Miocene age (Novković et al., 1975; Marovićet al., 1990; Nikolić and Maksimović, 1990). The totalproduction during the period 1965–2000 was about 5Mtof low-rank coal. Coal resources and reserves are esti-mated at 200Mt.

Previous petrographical investigations were providedby Ercegovac (1998), and Ercegovac et al. (2006). Bio-marker investigations have not been previously carriedout. Potentially toxic trace elements were studied byŽivotić et al. (2005).

The aim of this study was to investigate the coalfacies, obtain more information on the molecularcomposition of the saturated hydrocarbon fractions,interpret the peat forming environments, and establishthe contents of the major and trace elements in the coaland related sediments.

2. Geological setting

The basement of the Soko Banja basin is comprisedof Proterozoic schist, Devonian schist and sandstone,Carboniferous schist and claystone with a thin coal bed,Permian sandstone, Triassic sandy limestone, UpperJurassic dolomite and limestone, and Upper Cretaceouslimestone (Figs. 1, 2).

The Tertiary sediments, hosting the low-rank coalseams, consist of conglomerate, sandstone, marlstone,and clay. The total thickness of the Lower Palaeogeneis estimated at 500m and of the Neogene sediments at950 m. Four series (Novković et al., 1975) of sedimentsare recognized within the coal-bearing strata (Fig. 2a):

1. The Lower Palaeogene Series (Palaeocene–Eocene)was formed in a narrow graben (5–8 km) in the NEpart of the basin. This series commences, after un-conformity over Upper Cretaceous limestone, withtransgressive reddish quartz, conglomerate and thick-bedded sandstone, which are overlain by bituminous-bedded limestone, yellow and olive-green beddedfine-grained sandstone with volcanoclastics andlaminated oil shale. The age of the Lower Palaeogeneseries was determined by the Archeolithothamniumlugeoni Pfender, which was found in the bituminouslimestone.

2. The Čitluk Series (probably Lower Miocene) overliestransgressively both Lower Palaeogene and olderformations. The Čitluk Series consists in the bottomparts of conglomerate, grey thick-bedded sandstonewith clay lenses and grey laminated marlstone withlenses of marly and carbonaceous clay. The overlyingcoal-bearing horizon consists of grey marly clay, theMain coal seam, and bedded yellow marlstone andsandstone with a high concentration of methane. Theuppermost part of the Čitluk Series consists of yellowand grey marlstone, grey bedded sandstone, the uppercoal seam (0.5–3 m thick) and grey marly clay. Onlythe older, main, coal seam has been in exploitationsince 1928 (Simić, 1958). The maximum thickness ofthe main coal seam is approximately 43 m with theaverage being 23 m (Novković et al., 1975; Nikolićand Maksimović, 1990). The coal seam dips north-wards at an angle of 20–45°. The sediments of theČitluk Series were deposited in a limnic environmentduring the Lower Miocene. Dolić (1998) suggests thelower part of the Lower Miocene (Egerian–Eggen-burgian; Rögl, 1996) for the precise age of the ČitlukSeries.

3. The Vrmdža Series (Lower Miocene?) is also trans-gressive and from bottom to top incorporates the

Fig. 1. Simplified geological map (a) of the Soko Banja basin (modified after Basic Geologic Map of the SFRJ) with location of the cross section, sample location, position of the basin and crosssections A–B (modified after Novković et al., 1975).

287D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306

Fig. 2. Lithostratigraphic column (a) of the Soko Banja basin (after Novković et al., 1975, modified by Dolić, 1998) with absolute position of thesamples (b) and reconstructed samples position in the Main coal seam (c).


289D. Životić et al. / International Journal of Coal Geology 73 (2008) 285–306

following sediments: grey to red conglomerate andgravel, red loose bedded sandstone, laminated greymarlstone with lenses of sandstone and clay, bentoniteclay, tuff, marly clay and sandy marlstone with a thinuneconomical low-rank coal layer. The age of thisseries was erroneously determined by previousresearchers as the Middle Miocene. According tosedimentological, micro- and macropalaeontologicalinvestigation, Dolić (1998) concluded that the VrmdžaSeries was deposited in a limnic environment duringthe upper part of the Lower Miocene (Ottnangian;Rögl, 1996), before the Paratethys transgression.

4. The Upper Series (Upper Miocene?), transgressivelyoverlying the Vrmdža Series, consists of clastic sedi-ments, red, grey to green sand and gravel, occasion-ally with clayey cement. The age is supposed to beeither the uppermost Pontian or the Lower Pliocene.

The most important Soko Banja, Vrmdža, and Rtanj-Krstatac faults strike E–W, WNW–ESE, NW–SE,respectively (Marović et al., 1990; Fig. 1a). There arealso minor faults running N–S, which, together with thepreviously mentioned, control both the general contourand the shape of the basin.

3. Samples and analytical methods

Ten channel coal samples and two carbonaceous claysamples were collected from three fresh, working facesin the Soko underground coal mine, from different partsof the main coal seam (Čitluk Series; Figs. 1a, 2b). Thereconstructed column, with relative sampling positions,is given in Fig. 2c.

The samples were ground to b150 μm and analysedon a Vario EL III CHNOS Elemental Analyzer, and onan IKA-Calorimeter adiabatic C400 (JUS B. H8.318).

For rank determination and maceral analyses, the coalsamples were crushed to a maximum particle size of3 mm, mounted in epoxy resin and polished. The maceralanalyses were performed on a Leitz DMLPmicroscope inmonochromatic and UV light on 500points. The maceraldescription used in this article follows the terminologydeveloped by the International Committee for CoalPetrology for low-rank coal (Sykorova et al., 2005).

The reflectance measurement was performed inmonochromatic light of 546nm using a Leitz MPVIImicroscope and an optical standard having a reflectanceof 0.589% in oil, following the procedures outlinedby Taylor et al. (1998). The rank was determined bymeasuring the random reflectance on ulminite B.

The pulverised coal samples were extracted for 24husing a Dionex ASE apparatus employing isohexane/

acetone as the solvent at a temperature of 80 °C and apressure of 8MPa. After extraction,most of the solvent wasremoved using a rotary vacuum evaporator. The extractyields were weighed, the asphaltenes were precipitatedwith petroleum ether and the remainder was separated intothree fractions using column chromatography over silicagel and aluminium oxide. The saturated hydrocarbonsfraction was eluted with isohexane, the aromatic hydro-carbons with dichloromethane and the heterocompounds(N, S, O compounds) with dichloromethane/methanol.

The saturated hydrocarbons were then separated on a30mDB5 quartz capillary column (0.32mm ID 0.17 μm)in a Hewlett Packard 5890 gas chromatograph connectedto a HP 5972 Mass Selective Detector (MSD). Heliumwas used as the carrier gas (1.04ml/min). The injector,operating in the split-less mode, was held at 250 °C, andthe column temperature was started at 100 °C, held for2min, and then ramped at 5 °C/min to 300 °C.

Identification of abietane, dehydroabietane andphyllocladane were obtained by co-injection of authen-tic standards to confirm the identification based on massspectrometry. The other individual compounds wereidentified by retention time in the total ion current (TIC)chromatogram and by comparison of the mass spectrawith published data (Philp, 1985).

For XRF analysis, 1g of pulverised sample was used.First the loss on ignition, LOI, was determined at 1030 °C.If the LOI was b25%, 5 g LiBO2 were added; if the LOIwas N25%, 2.5 g LiBO2+2.4g Li2B4O7 were used. Then,this mixture was fused for 20min at a temperature of1200 °C. The formed borate glasses were used for theXRF analysis.

For the ICP-MS analysis, microwave digestion about200 mg sample (b40 μm) were weighed into PTFEvessels, 2 ml HF (50%)+5 ml HNO3 (65%)+2 ml H2O2

(30%) were added and microwave digested 1h at atemperature of 210 °C. The vessels were left overnightin a deep freezer to cool down. Then the digestion liquidwas evaporated at 90 °C under vacuum, which tookabout 1h. The residue was then dissolved in 1 ml HCl(32%)+8 ml deionised water+1 ml HNO3 (65%). Thissolution was then transferred into 125 ml FEP bottleswhich were filled up to 100g with deionised water. Thissolution was employed for the ICP-MS analysis.

Major and some trace elements (Al, Ca, Cl, F, Fe, K,Mg, Na, P, S, Si, As, Ba, Bi, Ce, Co, Cr, Cs, Cu, Ga, Hf,La, Mo, Nb, Ni, Pb, Rb, Sb, Sn, Sr, Ta, Th, Ti, U, V, W,Y, Zn, Zr) in coal were analysed using X-rayfluorescence (XRF). Trace elements (Ag, As, B, Ba,Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Ga, Ge, Hf, Hg, In, La,Li, Mn, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Se, Sn, Sr, Ta, Te,Th, Ti, Tl, U, V, W, Y, Zn, Zr, REE) were analysed using

Fig. 4. Diagram of the H/C and O/C ratios.


inductively coupled plasma-mass spectrometry (ICP-MS) at the Bundesanstalt für Geowissenschaften undRohstoffe (BGR) laboratories in Hannover, followingthe procedures outlined by Meier et al. (1996).

4. Results and discussion

4.1. Macropetrography and ash content

The macroscopic seam profile, together with thevertical distribution of the ash yields, parameters ofultimate analysis, calorific value and huminite reflec-tance, is shown in Fig. 3. The base of the seam consistsof carbonaceous clay and the roof of the seam consistsof marlstone. Xylite-rich coal (Taylor et al., 1998)predominated in the upper and lower part of the seam,while matrix coal predominated in middle part of theseam. Charcoal is rare in the Main coal seam, but smallfragments, dimension of 3 mm, were found in the upperpart of the seam. The ash content (dry basis) of the coalsamples from the Soko Mine (Soko Banja basin) rangesbetween 4.36wt.% in the xylite-rich coal and 25.87wt.%in the matrix coal from the upper part of the seam(Table 2), but in the carbonaceous clay, in the lower partof the seam, it was over 50.00wt.% (samples Soko 10/1and Soko 10/2). Generally speaking, the matrix coal hasslightly higher ash content than the xylite-rich coal.

Fig. 3. Macropetrographic profile of the Soko Banja coal and vertical distrcontent, calorific value and huminite reflectance.

4.2. Ultimate analysis

The results of the approximate and ultimate analysis ofthe organic matter from the studied samples are shown inTable 2. Coal from the SokoMine has a relatively low totalcarbon content (63.72–67.62wt.%) and a relatively highoxygen content (22.56–26.38wt.%, dry, ash-free basis),

ibution of ash, total carbon, hydrogen, oxygen, nitrogen, and sulphur

Table 1Maceral composition (vol.%), huminite reflectance (%) and petrographic indices of the Soko Banja coals

Sample Soko 1 Soko 2 Soko 3 Soko 4 Soko 5 Soko 6 Soko 7/1 Soko 7/2 Soko 8 Soko 10/1 Soko 10/2 Soko 11

Maceral composition (vol.%)Textinite A 1.0 0.8 0.2 0.8 3.5 1.9 0.5 2.3 0.8 1.0 2.8Textinite B 1.1 0.6 4.6 1.9 3.1Ulminite A 26.1 33.2 17.2 31.6 20.0 20.3 8.9 21.6 31.8 16.2 10.6 11.6Ulminite B 15.7 2.8 18.6 4.2 7.6 2.8 22.7 3.6 6.8 0.8 0.8 21.9(Total telohuminite) 42.8 36.8 37.1 36.6 31.7 25.0 36.7 27.5 41.3 18.0 14.2 36.6Attrinite 1.4 2.9 0.8 0.4 2.6 8.6Densinite 12.7 14.9 20.6 5.9 18.1 33.9 18.9 28.8 20.7 11.5 15.2 25.3(Total detrohuminite) 12.7 14.9 22.0 8.8 18.1 34.7 18.9 29.2 20.7 14.1 23.8 25.3Porigelinite 1.6 2.6 1.4 4.0 7.6 3.2 5.4 4.5 6.2 2.3 1.0 2.1Levigelinite 13.0 29.1 8.0 11.8 11.4 12.2 17.0 8.8 10.3 8.4 5.4 20.3Phlobaphinite 9.2 2.6 5.7 8.6 5.5 6.0 1.4 3.9 1.4 5.4 3.5 0.8Pseudophlobaphinite 1.0 1.2 0.5 2.1 1.7 1.1 0.4 0.6 0.8 0.2 0.5(Total gelohuminite) 24.8 35.5 15.6 26.5 26.2 22.5 23.8 17.6 18.5 16.9 10.1 23.7Total huminite 80.3 87.2 74.7 71.9 76.0 82.2 79.4 74.3 80.5 49.0 48.1 85.6Sporinite 2.0 1.2 2.4 2.6 2.3 3.7 3.8 3.8 3.7 1.1 0.8 2.9Cutinite 1.0 0.3 0.2 0.8 0.6 0.4 0.5 0.6 0.2 0.3 0.5Resinite 2.0 0.8 0.9 0.4 2.0 1.5 0.8 0.9 0.4 0.3 1.8 0.3Suberinite 1.0 0.2 0.4 8.2 0.8 0.6 0.3 0.5 0.3Alginite 0.4 0.2 0.5 0.3 0.5Liptodetrinite 2.9 0.3 1.1 0.2 0.9 0.8 1.9 0.9 1.7 0.5 0.3 0.9Bituminite 0.3 0.7 0.2 0.5 0.9 0.3 0.5 0.3Fluorinite 0.5 0.4 0.2Total liptinite 7.9 3.9 5.5 4.8 14.0 7.6 8.0 8.1 6.2 3.3 4.7 5.2Fusinite 3.3 1.3 2.3 0.4 0.6 0.4 0.3 0.2 1.9 0.2 1.3Semifusinite 0.3 0.7 0.5 0.2 0.6 0.2 0.3 1.2 0.7Macrinite 0.5 0.7 0.2 0.3 0.2Funginite 0.7 1.5 1.1 0.4 1.5 0.8 2.2 1.3 0.6 1.0 1.0 0.5Inertodetrinite 1.6 2.5 4.6 1.1 0.9 1.3 0.5 0.8 3.9 0.3 2.6Total inertinite 5.9 6.5 9.2 2.3 3.6 2.7 3.6 2.3 7.6 1.0 1.7 5.1

Mineral matter (vol.%)Clay 2.3 0.7 5.3 9.2 2.9 3.6 2.4 0.9 1.9 8.4 34.1 3.1Pyrite 3.6 1.3 3.2 3.2 3.2 2.4 4.1 1.1 1.9 0.3 2.1 0.5Carbonates 0.3 0.7 0.2 0.3 1.1 2.2 13.3 1.7 1.0 0.2 0.3Mineral-bituminous

groundmass8.0 0.4 0.3 35.7 5.4

Other minerals 1.4 0.4 0.2 1.3 3.7 0.2Total mineral 5.9 2.3 10.6 21.0 6.4 7.5 9.0 15.3 5.7 46.7 45.5 4.1Average huminite

reflectance (%)0.34±0.02

0.40±0.03

0.35±0.04

0.32±0.03

0.42±0.05

0.42±0.05

0.48±0.04

0.38±0.04

0.41±0.05

0.35±0.05

0.35±0.03

0.47±0.04

TPI 1 1.61 0.78 1.09 1.44 0.87 0.50 0.89 0.64 1.08 0.73 0.47 0.77GI 2 11.49 11.84 6.05 11.37 9.34 14.72 8.54 14.32 7.55 9.87 2.80 10.06

1 TPI=(Textinite+Ulminite+Corpohuminite+Fusinite+Semifusinite) / (Gelinite+Macrinite+Detrohuminite), by Diessel (1986) and modified byErcegovac and Pulejković (1991).2 GI=(Ulminite+Densinite+Gelinite+Corpohuminite) / (Textinite+Attrinite+ Inertinite), by Diessel (1986) and modified by Ercegovac and

Pulejković (1991).


hydrogen content (5.62–6.52wt.%, dry, ash-free basis),nitrogen content (1.12–2.17wt.%, dry, ash-free basis) andsulphur content (1.06–3.56wt.%, dry, ash-free basis). Thehighest value of the total carbon content was determinedin the xylite-rich coal from the upper part of the seam(Fig. 3). The highest hydrogen content was determined inmatrix coal, also from this part of the seam. The lowest

sulphur content was located in the lower and the highest inthe upper part of the seam.

According to the ultimate analyses, samples 10/1 and10/2 are completely different from the other samples,except for the sulphur content. These differences arereflected in the H/C and O/C ratios (Table 2) and are evenmore obvious using these ratios on a vanKrevelen diagram

Table 2Depth, ash yield, gross and net calorific value, content of carbon, hydrogen, oxygen, sulphur and nitrogen, hydrogen/carbon ratio, oxygen/carbonratio, carbon/nitrogen ratio, extract yield, relative percentages of alkanes, aromatics, asphaltenes and resins

Sample Depth (m) Adb Qgdaf Qn

daf Cdaf Hdaf Odaf Sdaf Ndaf H/C O/C C/N Extractyield(ppm)

Alkanes(wt.%)

Aromates(wt.%)

Asphaltenes(wt.%)

Resins(wt.%)

Soko 1 462.30–463.16 4.36 27.73 26.47 67.62 6.14 23.38 1.75 1.12 1.09 0.26 70.48 11164 15.1 7.6 46.9 30.5Soko 2 463.16–464.00 5.47 26.52 25.36 66.85 5.62 24.51 1.49 1.53 1.01 0.27 50.82 12785 4.1 7.3 56.0 32.6Soko 3 464.00–465.10 15.83 25.96 24.75 63.72 5.86 25.48 3.56 1.38 1.10 0.28 53.91 12429 5.8 8.1 49.3 36.8Soko 4 465.10–466.30 25.87 25.59 24.25 64.91 6.52 24.86 2.13 1.58 1.20 0.27 47.96 9413 20.1 14.7 28.1 37.1Soko 5 454.37–455.26 9.84 26.13 24.89 65.49 5.99 24.45 2.22 1.85 1.10 0.27 41.23 13245 5.1 3.2 70.4 21.4Soko 6 455.26–456.01 13.75 26.40 25.17 66.03 6.02 23.72 2.24 1.99 1.09 0.25 38.61 12911 4.6 6.0 53.2 36.2Soko 7/1 456.01–456.54 10.51 25.36 24.09 66.42 6.15 23.94 2.03 1.46 1.11 0.28 52.91 12646 6.0 6.4 67.1 20.5Soko 7/2 456.54–456.89 10.27 26.64 25.32 67.01 6.37 22.56 1.88 2.17 1.14 0.27 35.96 13230 5.4 2.9 63.9 27.7Soko 8 473.90–474.40 8.43 26.12 24.90 65.99 5.89 24.89 1.37 1.87 1.07 0.28 41.21 13911 1.5 2.1 76.2 20.2Soko 10/1 473.20–473.70 52.90 22.80 21.30 59.66 7.26 28.87 2.12 2.08 1.46 0.70 33.44 13110 3.8 5.4 60.3 30.5Soko 10/2 472.85–473.20 51.46 21.94 20.45 57.07 7.23 30.74 2.78 2.18 1.52 0.32 30.47 12981 4.9 5.2 50.6 39.3Soko 11 471.97–472.85 11.32 29.01 27.81 64.92 5.80 26.38 1.06 1.85 1.07 0.29 40.93 14096 1.0 1.3 54.2 43.4

Adb — ash content, dry basis, %; Qgdaf — gross calorific value, dry, ash-free basis, MJ/kg; Qn

daf — net calorific value, dry, ash-free basis, MJ/kg;Cdaf— carbon content, dry, ash-free basis, %; Hdaf— hydrogen content, dry, ash-free basis, %; Odaf— oxygen content, dry, ash-free basis, %; Sdaf—sulphur content, dry, ash-free basis, %; Ndaf — nitrogen content, dry, ash-free basis.


(Fig. 4). According to these criteria, the organic matter ofthe ten coal samples is very similar in composition andcorresponds to organicmatter between types III and II. Thedifferent origin of the organic matter and the variousconditions during evolution are reflected in the C/N ratio.The values of this parameter are over 20 in all the studiedsamples, which is typical for terrestrial flora as precursor(Tyson, 1995; Meyers and Lallier-Vergés, 1999). The C/Nratios (over 40) imply the predominance of higher plants(Meyers and Ishiwatari, 1993).

The high ash content in several samples is indicativeof periodic flooding of the mire during deposition. Therelatively high sulphur content in some samples formedin limnic deposition environments could be a result ofalkaline, calcium-rich surface waters derived from thesurrounding Jurassic and Cretaceous calcareous countryrock and changing pH-values, as reported for Velenjecoals (Markic and Sachsenhofer, 1997). Also, the rela-tively high sulphur content and the high amounts ofcoal-bed methane released during coal mining (Gagić,in press) suggest a high activity of anaerobic bacteria ina slightly acidic to neutral methanogenic environmentrich in sulphate ions.

4.3. Coal rank and quality

The results of huminite reflectance measurementsshow that the Soko Banja coal can be classified as adull brown coal (Ercegovac et al., 2006) or lignite tosubbituminous or Low-Rank B (ECE-UN, 1998, 1999,2000), with a mean random huminite reflectance for maincoal seam of 0.40±0.05. The coal from the main seam of

the Čitluk Series has mean random huminite reflectancevalues from0.32% (Soko 4; Table 1) to 0.48% (Soko 7/1).

The gross calorific value (dry, ash-free basis) of thecoal samples varies between 25.36 and 29.01MJ/kg(Table 2), except of the samples Soko 10/1 and Soko 10/2, which are much lower. The net calorific value (dry,ash-free basis) ranges from 24.09 to 27.81MJ/kg, whichis expected for a coal of this rank. The highest calorificvalue was observed in the xylite-rich coal from thelower part of the seam for the sample with a highhuminite reflectance (Soko 11; Fig. 3).

4.4. Micropetrography

The maceral analyses show that huminite is thedominating maceral group (71.9–87.2 vol.%; Table 1;Fig. 5) in the coal from the Main seam of the Soko Mine.The samples are characterised by relatively low content ofliptinite (3.9–14.0 vol.%) and inertinite (2.3–9.2 vol.%).Clay dominates in the mineral matter, while carbonates,pyrite and mineral-bituminous groundmass are lessabundant.

The huminite maceral group consists mainly oftelohuminite (25.0–42.8 vol.%), with ulminite (11.4–41.8 vol.%) as the most abundant maceral (Fig. 6a,c).They are present in two forms, huminite bands andhuminite groundmass. The huminite bands, in manycases, were formed of only ulminite macerals, but insome cases thick layers of gelinite or densinite areinterbedded with the ulminite layers. Ulminite type A ismore abundant than ulminite type B, while textiniteoccur in minor amounts. The telohuminite is strongly

Fig. 5. Macropetrographic profile of the Soko Banja coal and vertical distribution of maceral groups, gelification index, tissue preservation index, diterpane (abietane and phyllocladane), n-alkanes,CPI, and pristane and phytane ratio.

293D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306

Fig. 6. Characteristic macerals from the Soko Banja coal; a) ulminite (U) with corpohuminite (Ch); b) the same as a), UV light; c) ulminite (U) withresinite (R) bodies; d) the same as c), UV light; e) densinite (D), corpohuminite (Ch), sporinite (Sp), inertodetrinite (Id), pyrite (Py); f) the same as e),UV light; g) suberinite (Su) resinite (R) in Mineral matter, UV light; h) densinite (D), funginite (Fu) pyrite (Py).



impregnated by resinous-like substances (Fig. 6b). Thedetrohuminite (8.8–34.7 vol.%) occurs as groundmasssurrounding liptinite or inertinite particles, and, in somecases, densinite (5.9–33.9 vol.%; Fig. 6e,h) is interbeddedwith clayminerals. Attrinite is subordinate (0–2.9 vol.%),and the highest content was determined in the carbona-ceous clay, probable as a result of the high content ofmineral matter and low gelification of the organic matter.The gelohuminite content ranges between 15.6 and35.5 vol.%, most of which is gelinite (9.4–31.7 vol.%),in particular levigelinite. The levigelinite is present, inmany cases, in thick layers, sometimes interbedded withulminite or densinite. Porigelinite is less abundant, andusually occurs in thin bands. Corpohuminite (1.4–10.7 vol.%) is disseminated throughout the ulminite andtextinite, sometimes on densinite,mainly as phlobaphiniteof globular or tabular shape.

The content of liptinite macerals in Soko Banja coalsusually ranges from3.9 to 8.1 vol.%.Only one sample hasa slightly higher content (Soko 5; 14.0 vol.%). Sporinite,resinite, liptodetrinite, suberinite and cutinite are the mostcommon macerals of the liptinite group. Bituminite,fluorinite and alginite were rarely observed. The sporinitecontent varies between 1.2 and 3.8 vol.%. Most of themhave thin walls (tenuisporinite), while sporinite with athick-wall (crasisporinite) were found in traces. All ofthem have a pale yellow colour under fluorescence light(Fig. 4f). Resinite (0.4–2.0 vol.%), mostly occurs as cell-filling or isolated small globular bodies. They areassociated with telohuminite as single bodies (Fig. 6d),commonly as impregnation in telohuminite (Fig. 6b) andless with detrohuminite; they have a pale-brownish-yellow colour under fluorescent light. Liptodetrinite (0.2–2.9 vol.%) is usually associated with detrohuminite.Suberinite is normally less than 1.0 vol.%, except in onesample where its content was 8.2 vol.%, and usuallyappears as cell wall tissue associated with phlobaphinite.Under fluorescent light, suberinite has a greenish to paleyellow colour (Fig. 6g). Cutinite (0.0–1.0 vol.%) usuallyoccurs as the thin walled (tenuicutinite) variety. The thickwalled (crassicutinite) variety was rarely recognized. Ithas pale yellow fluorescence colour under light.

In the studied coals, bituminite (0.0–0.9 vol.%)appears as single bodies mainly in densinite-rich coal.Under florescence light, bituminite usually had a weakbrown or brownish yellow colour. Alginite (up to 0.5 vol.%) was observed in trace amounts (Table 1) and has anintense yellow colour under fluorescence light. Fluor-inite (up to 0.5 vol.%), with strong yellow colour underfluorescence light, was also found in trace amounts.

Inertodetrinite, funginite and fusinite are the mostcommon macerals of the inertinite group, while

semifusinite and macrinite are found in traces. Inertode-trinite (0.5–4.6 vol.%) is disseminated throughout thecoals. Funginite, including single and multi-celledfungal spores and sclerotia, occurs as single bodies oras colonies. The pores are usually filled with mineralmatter, rarely with resinite. Fusinite (up to 3.3 vol.%)occurs in thin bands. The pores are usually empty butsometimes they are filled with mineral matter.

The content of mineral matter varies between 2.3 and21.0 vol.% (except in carbonaceous clay; Table 1), mostof which is clay. The clay minerals (0.7–9.2 vol.%) areusually dispersed, but in some cases they formed thicklayers. The presence of a mixture of clay-rich and humic-rich intervals in the coal indicates that the water levelfluctuated and periodically brought inorganicmaceral intothe paleomire. Pyrite (0.5–4.1 vol.%) occurs as small,euhedral crystals or in a framboidal concretionary form.Its presence in the clay-rich and humic-rich layerssuggests anaerobic conditions coupled with sulphur-reducing bacterial activity. Carbonates usually rangefrom 0.2 to 2.2 vol.%, with only one sample having ahigh content (Soko 7/2; 13.3 vol.%). They are mainly ofclastic origin, and occur as crystals of irregular shape incoal fractures or cell lumens. Mineral-bituminousgroundmass, impregnation of detrohuminite with bitumi-nite (Teichmüller, 1989), identified in a few coal samples,and carbonaceous clay, indicate sub-aquatic origin andstrong bacterial decomposition. The highest value ofmineral-bituminous groundmass (35.7 vol.%) was ob-served in carbonaceous clay (Soko 10/1).

The tissue preservation index (TPI), as the ratiobetween structured and unstructured macerals of thehuminite and inertinite group, ranges from 0.50 to 1.61.Coals with well-preserved plant tissue (textinite andulminite) have a high TPI value. Generally speaking, theupper parts of the Main coal seam have higher TPI value(Fig. 5). The gelification index (GI), as the ratio ofgelified (ulminite, densinite, gelinite and corpohumi-nite) to non-gelified (textinite and attrinite) macerals,may indicate the relative humidity or oxidation in themire. Coals from Soko Banja generally have a high GIvalue, ranging between 6.05 and 14.72.

4.5. Molecular composition of the organic matter

The extract yields from the coal of the Soko Mineranges from 9413 to 14096 ppm (Table 2). All theextracts are mainly composed of heterocompounds(asphaltenes+resins; Table 2). In most of the extractsof Soko Banja coal, aromatic hydrocarbon (aromatics)are more abundant than saturated hydrocarbons(alkanes), with the exception of four samples (Soko 1,

Fig. 7. Typical gas chromatograms (total ion current, TIC) of the saturated hydrocarbon fraction from the Soko Banja coal; (a) sample Soko 1, (b) sample Soko 3, (c) sample Soko 5, (d) sample Soko 8;1— abietane, 2— 16α(H)-phyllocladane, 3— dehydroabietane, Pr— pristane, Py— phytane, n-alkanes are marked by dots, and odd-numbered homologues are additionally labelled according totheir carbon number. Hopanoids are marked by diamonds.

296D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306

Table 3Dominant peak, carbon number max, proportions of C15–19, C21–25,and C27–31 n-alkanes to the sum of the n-alkanes, pristane/phytaneratios, and carbon preference index of the Soko Banja coal

Sample Dominantpeak

Carbonnumbermax

n-C15–

19/n-C15–32

n-C21–

25/n-C15–32

n-C27–

31/n-C15–32

Pr/Ph CPI

Soko 1 Abietane n-C20 0.35 0.16 0.01 1.14 1.89Soko 2 Abietane n-C21 0.17 0.37 0.07 0.86 1.38Soko 3 16α(H)-

Phn-C23 0.18 0.41 0.04 1.39 2.88

Soko 4 Abietane n-C23 0.14 0.44 0.04 1.55 3.21Soko 5 n-C29 n-C29 0.09 0.13 0.63 3.13 15.93Soko 6 n-C29 n-C29 0.05 0.17 0.56 2.40 7.07Soko

7/1n-C29 n-C29 0.05 0.20 0.57 0.56 15.91

Soko7/2

n-C29 n-C29 0.04 0.07 0.75 2.11 11.39

Soko 8 n-C24 n-C24 0.08 0.31 0.23 2.14 3.75Soko

10/1n-C29 n-C29 0.06 0.16 0.55 1.44 6.09

Soko10/2

n-C29 n-C29 0.05 0.24 0.53 1.90 7.95

Soko11

n-C24 n-C24 0.05 0.26 0.33 1.78 5.32

16α(H)-Ph — 16α(H)-phyllocladane; Pr — pristane; Py – phytane.CPI ¼ 1

2 � C25þC27þC29þC31ð ÞC24þC26þC28þC30ð Þ þ C25þC27þC29þC31ð Þ

C26þC28þC30þC32ð Þ, (Bray andEvans, 1961).


Soko 4, Soko 5 and Soko 7/2). The variation in thealkane content has been related to the origin of plantmaterial and to the intensity of biochemical degradationof the plant material (Hagemann and Hollerbach, 1979).

4.5.1. n-Alkanes, isoprenoidsThe n-alkane fraction comprises saturated hydrocarbons

in theC15–C32 range,with an odd-over-even predominance(Bray and Evans, 1961). Typical gas chromatograms (TIC)of the alkane fraction of the Soko Banja coals are shown inFig. 7. The n-alkane distributions of the Soko Banjacoals revealed that either mid-chain (n-C21–25) or long-chain (n-C27–32) compounds dominate (Table 3). Low-chain n-alkanes (bn-C20) were detected in lowconcentrations. The relative proportions of short-chain(n-C15–19), mid-chain (n-C21–25), and long-chain (n-C27–32) n-alkanes relative to the sum of n-alkanes showvariation with depth (Fig. 5). The predominance of mid-chain n-alkanes is obvious in upper part, long-chain incentral and lower part, and short-chain n-alkanes in theuppermost part of Main coal seam.

Long-chain lipids are the main components of plantwaxes (Eglinton and Hamilton, 1967), and are wellknown as biomarkers for higher terrestrial plants.During early diagenesis, they are preferentially degrad-ed by microbial activities to aldehydes, ketones andalkanes (Cranwell et al., 1987; Püttmann and Bracke,1995). This degradation pathway and continued degra-dation of aldehydes favours n-alkanes with an oddnumber of carbon atoms. The analyses of extracts fromthe studied basin suggest a major contribution ofterrestrial plants to the organic matter in the centralpart, and some samples in the lower part of the Maincoal seam (Fig. 5). In samples Soko 5, Soko 6, Soko 7/1,Soko 7/2, Soko 10/1 and Soko 10/2 the distribution ofn-alkane shows a predominance of odd carbon num-bered homologues (CPI value ranges between 6.09 and15.93; Table 3) and a maximum abundance at C29,indicating land plants as the dominant source of organicmatter. Resent studies provided by Otto et al. (2005)suggest that angiosperm leaves are characterised by highintensities of long-chain n-alkanes with a maximum atn-C29 (Betula sp., Quercus sp.).

Mid-chain n-alkanes (C21–25) are present in significantamounts in the samples from the upper part of the mainseam. Possible biological precursor of these compoundscould be vascular plants, microalgae and cyanobacteria(Giger and Schaffner, 1977; Matsumoto et al., 1990).The predominance of odd over even carbon number in then-alkanes fractions suggests microbial origin of the lowermolecular weight n-alkanes through degradation (Allenet al., 1971; Cranwell et al., 1987; Otto et al., 1995). A

predominance of mid-chain n-alkanes was observed inSoko 2, Soko 3, Soko 4, Soko 8 and Soko 11 samples,with CPI values 1.38–5.32 (Table 3). The similaritybetween samples Soko 8 and Soko 11 with a dominationof n-C24, may indicate the presence of epicuticular waxesfrom gymnosperm (Pinus). A study of peat samples byDehmer (1995) suggests herbaceous types as possiblebiological precursors. Otto and Simoneit (2001) foundhigh amounts of mid-chain n-alkanes in cone and shootsof some fossil conifer species (Taxodium balticum,Athrotaxis couttsiae, and Pinus paleostrobus).

Short-chain n-alkanes (bC20), predominantly foundin algae and microorganisms (Cranwell, 1977), occur inrelatively low amounts. The higher amount of the short-chain n-alkanes in sample Soko 1 (Table 3), could beexplained by the reduction of n-fatty acids and alcoholsfrom waxes in very reducing environments (Welte andWaples, 1973).

Acyclic isoprenoid hydrocarbons are minor constitu-ents of the aliphatic fraction, and the pristane/phytaneratio varies between 0.56 and 3.13 (Table 3). Lowpristane/phytane ratios (b 1; Soko 2, and Soko 7) indicateanaerobic conditions during sedimentation, whereasvalues over 1 suggest oxic conditions (Peters andMoldowan, 1993). The pristane/phytane ratio is known


to be a maturation parameter (Tissot andWelte, 1984) andis affected by differences in the precursors of acyclicisoprenoids (bacterial origin; ten Haven et al., 1987).Based on the maceral composition and the most probableorigin of pristane and phytane from chlorophyll in landplant-dominated organic matter, the pristane/phytaneratios are interpreted as reflecting changes in the redoxconditions of the mire, as reported by Markic andSachsenhofer (1997) and Bechtel et al. (2003b). Thehigh pristane/phytane ratio (over 1, except in the samplesSoko 2 and Soko 7) results from oxidation conditionswhich favoured microbiological degradation.

4.5.2. DiterpenoidsThe dominant peaks in the total ion current (TIC) of the

hydrocarbon fractions of samples from the upper part of theseam are diterpenoids (Table 3; Figs. 5, 7a,b), which aremainly represented by tricyclic compounds (abietane,dehydroabietane), and one tetracyclic compound(16α(H)-phyllocladane). In the samples Soko 1, Soko 2and Soko 4, abietane is the major compound, whereas it is16α(H)-phyllocladane in the Soko 3 sample. In othersamples, where the n-C24 is the major constituent, 16α(H)-phyllocladane is also present in low amounts, whereas insamples with predominance of n-C29 it is absent. Abietaneis present in low or minor amounts in these samples.

The presence of abietane in all samples and 16α(H)-phyllocladane in some samples in aliphatic fractionimplies that gymnosperms contribute to peat-formationin the Soko Banja coals. Phyllocladane is well known asthe major diterpenoid of many European Tertiary low-rank coals: Hungarian Nograd Basin (Alexander et al.,1987); German Oberpfalz region (Dehmer, 1989);Bulgarian “Maritza-Iztok” deposit (Stefanova et al.,1995; Bechtel et al., 2005) and Chukurovo lignite(Stefanova, 2004); Serbian Kosovo basin (Milićevićet al., 1996); Greek Florina basin (Papanicolaou et al.,2000); Austrian Eastern Alps coal (Bechtel et al., 2001),Oberdorf lignite (Bechtel et al., 2002), Hausruch lignite,Alpine Foreland Basin (Bechtel et al., 2003a); SlovenianVelenje lignites (Bechtel et al., 2003b) and Trbovlje coal(Bechtel et al., 2004). It was also identified in some low-rank coals from Canada (Kalkreuth et al., 1998), China(Wang and Simoneit, 1990; Ming et al., 1994), peats(Dehmer, 1995), and Oligocene clay sediments (Ottoet al., 1995, 1997). For abietane, the situation is slightlydifferent. In almost all of the above-mentioned coalbasins, except in the Kalavryta coals (Greece; Papani-colaou et al., 2000), abietane is present in minor or traceamounts. In the upper part of the main coal seam fromthe Soko Banja basin, diterpanes occur in high amounts,with a domination or predominance of abietane.

Terpenoids and aliphatic lipids are widely distributedin fossil conifer, shoots, cones, leaves, and resins.Therefore, it is suggested that conifers contributed to thehigher relative abundance of terpenoids and minoramounts of aliphatic lipids in the coals. Terpenoidbiomarkers were found to be very valuable chemosyste-matic markers for conifers (Otto and Wilde, 2001; Ottoet al., 2003). Triterpenoids of the oleanane-, ursane- andlupane-type are considered as indicators for angios-perms and diterpenoids as conifer markers (Wang andSimoneit, 1990; Otto and Simoneit, 2001; Bechtel et al.,2002, 2003a,b, 2004; Otto et al., 2002, 2003, 2005).

Some diterpenoids of abietane structural classes arecommon natural products in many conifer families. Theobtained results indicate that “regular” abietanes werepreserved in the coal and marly clay samples from theSoko Mine. The “regular” abietanes are distributed in allconifer families (Pinaceae, Cupressaceae s. str., Taxodia-ceae, Podocarpaceae, Araucariaceae and Taxaceae),except Phyllocladaceae (Otto and Wilde, 2001). Phyllo-cladane-type diterpenoids (16α(H)-phyllocladane) aredistributed in Cupressaceae s. str., Podocarpaceae,Araucariaceae, Taxodiaceae, Sciadopityaceae and Phyl-locladaceae but not in Pinaceae, with the exception ofPicea jezoensis (Otto and Wilde, 2001). A positivecorrelation between the TPI and relative abundance ofabietane (r=+0.59), 16α(H)-phyllocladane (r=+0.75)and dehydroabietane (r=+0.51) suggest that preservationof plant tissue was primarily controlled by the presence/absence of decay-resistant gymnosperms in the mire.

The aromatic hydrocarbon fraction consisted ofmonoaromatic diterpenoids of the abietane type,dehydroabietane (Philp, 1985). It is present in highamounts in the upper part of the coal seam and in lowamounts in the other parts of the coal seam. Aromaticditerpenoids, such as dehydroabietane, simonellite andretene, are degradation products of abietic acid (Simo-neit et al., 1986), formed in anaerobic or a combinationof aerobic and anaerobic processes. Also, pimarane- andphyllocladane-derivates were reported (Wakeham et al.,1980; Alexander et al., 1987) as possible precursor foraromatic abietane-type diterpenoids. Under acidic con-ditions, isomerisation of pimarane and phyllocladanecatalysed by clay minerals led to the formation ofabietane and, subsequently, of dehydroabietane.According to the low maturity of the coal, enhancedaromatisation of terpenoid biomarkers in the Soko BanjaBasin was probably related to microbial activity.

4.5.3. Hopanoids, steroidsPolycyclic alkanes of the hopane type (m/z 191) are

important constituents of alkane fractions. The Soko Banja

Fig. 8. Typical gas chromatograms of the hopane fraction (m/z 191) from the Soko Banja coal; (a) sample Soko 3, (b) sample Soko 6, (c) sample Soko 8, (d) sample Soko 7/1; H1 — C2717α(H)-trisnorhopane; H2— C2717β(H)-trisnorhopane; H3— C2917α,21β (H)-30 norhopane; H4— C2918α (H)-30 norneohopane; H5— Hop-17(21)-ene; H6— C2917β,21α (H)-30 normoretane; H7—Hop-22(29)-ene (?); H8 — C31αβ homohop17(21)ene (S+R); H9 — C3017β,21β (H)-hopane; H10 — C3117β,21β (H)-homohopane.

299D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306

Table 4Major and trace elements in Soko Banja coal; range for coal samples (without samples Soko 10/1 and 10/2); AM: arithmetic mean value for coal (without samples Soko 10/1 and 10/2); GM: geometricmean value for coal (without samples Soko 10/1 and 10/2); Clarke value for coal and coal ash; World lignite value

Soko1

Soko2

Soko3

Soko4

Soko5

Soko6

Soko7/1

Soko7/2

Soko8

Soko10/1

Soko10/2

Soko11

Range(coal) AM(coal)

GM(coal)

Clarke values a World lignite b

Coal Coal ash AM GM

XRFAl, % 0.101 0.042 1.948 3.498 0.545 0.318 1.318 0.180 0.286 8.542 7.160 0.757 0.042–3.498 0.899 0.438 ND ND ND NDCa, % 0.697 0.853 0.923 0.780 1.349 1.628 1.557 3.508 1.575 0.803 1.119 1.451 0.697–3.508 1.432 1.279 ND ND ND NDCl, % 0.002 0.005 0.003 0.003 0.003 0.004 0.004 0.005 0.004 0.012 0.007 0.008 0.002–0.005 0.004 0.004 0.012 c 0.077 c 0.0099 0.0012F, % b0.050 b0.050 0.050 b0.050 0.060 b0.050 b0.050 b0.050 b0.050 b0.050 b0.050 b0.050 0.050–0.060 0.055 0.055 0.008 0.05–

0.10.0118 0.0058

Fe, % 1.147 0.392 1.420 2.273 1.245 1.357 0.853 1.700 0.972 1.658 1.979 0.336 0.336–2.273 1.170 1.015 ND ND ND NDK, % 0.089 0.080 0.174 0.384 0.042 0.037 0.093 0.066 0.044 1.023 0.687 0.052 0.037–0.384 0.106 0.080 ND ND ND NDMg, % 0.211 0.289 0.446 0.519 0.374 0.314 0.422 0.416 0.416 0.784 0.742 0.410 0.211–0.519 0.382 0.371 ND ND ND NDNa, % 0.128 0.173 0.271 0.302 0.241 0.234 0.256 0.136 0.204 0.339 0.347 0.264 0.128–0.302 0.221 0.213 ND ND ND NDP, % 0.008 0.005 0.006 0.007 0.007 0.006 0.010 0.015 0.013 0.018 0.019 0.019 0.005–0.019 0.010 0.009 0.013 0.1 0.0338 0.0123S, % 0.617 0.693 0.417 0.316 0.881 1.109 0.833 0.933 0.949 0.084 0.124 0.485 0.316–1.109 0.723 0.675 ND ND 2.42 1.93Si, % 0.112 0.065 3.202 6.216 0.626 0.271 1.762 0.131 0.238 14.998 12.292 0.729 0.065–6.216 1.335 0.500 ND ND ND ND

ICP-MS (mg/kg)Ag 0.270 0.082 0.098 0.054 0.017 0.046 0.020 0.011 0.017 0.014 0.370 0.027 0.011–0.270 0.064 0.040 0.3 1 0.08 0.02As 10.40 1.55 9.13 26.40 5.47 4.36 8.20 3.84 22.20 22.00 8.68 2.58 1.55–26.40 9.413 6.642 7.4 d 49 d 33.37 12.68B 29.30 30.20 20.40 10.70 24.00 18.20 27.20 20.00 37.50 36.60 22.00 31.10 10.70–37.50 24.860 23.597 85 560 128.66 46.15Ba 126.0 114.0 124.0 97.5 111.0 125.0 90.2 104.0 147.0 148.0 143.0 169.0 90.2–169.0 120.770 118.833 120 890 249.91 78.79Be 0.014 0.016 0.450 0.610 0.130 0.310 0.009 0.023 0.480 0.480 0.940 0.270 0.009–0.610 0.231 0.096 2.4 11 2.41 1.22Bi 0.033 0.017 0.120 0.180 0.028 0.055 0.053 0.017 0.021 0.026 0.370 0.041 0.017–0.180 0.057 0.041 ND ND 1.13 0.91Cd 0.035 0.037 0.072 0.150 0.061 0.057 0.097 0.035 0.120 0.120 0.100 0.052 0.035–0.150 0.072 0.063 0.3 3 5.58 0.20Ce 0.96 1.01 9.30 12.70 3.21 5.36 1.60 1.79 3.69 3.89 11.80 5.18 0.96–12.70 4.480 3.186 100–

200ND 25.20 12.88

Co 0.45 0.32 2.00 5.54 1.15 2.23 1.03 0.26 7.24 7.27 8.32 1.37 0.26–7.24 2.159 1.269 3.4 20 32.01 2.65Cr 1.02 0.63 17.10 28.30 5.54 7.63 2.91 1.18 3.70 3.68 66.70 3.24 0.63–28.30 7.125 3.744 12 70 54.53 9.89Cs 0.044 0.027 1.760 2.150 0.410 1.010 0.320 0.110 0.240 0.250 2.870 0.570 0.027–2.150 0.664 0.313 0.4–2 ⁎ ND 1.63 0.39Cu 2.82 3.02 20.90 28.10 4.05 4.66 2.99 2.41 4.41 4.36 67.50 3.17 2.41–28.10 7.653 4.987 7.5 48 35.32 6.99Ga 0.30 0.16 3.84 6.54 1.23 2.59 0.73 0.40 0.70 0.76 14.60 1.71 0.16–6.54 1.820 1.030 7 36 5.22 2.86Ge 0.026 0.059 0.340 0.560 0.190 0.330 0.130 0.054 0.490 0.460 0.560 0.230 0.026–0.560 0.241 0.164 1.5 9 2.55 1.49Hf 0.110 0.036 0.680 1.200 0.200 0.710 0.110 0.091 0.180 0.180 1.900 0.360 0.036–1.200 0.368 0.223 ND ND 3.11 0.28Hg 0.044 b0.010 0.062 0.130 0.001 0.033 b0.010 b0.010 0.140 0.119 0.006 0.130 0.001–0.140 0.077 0.042 0.1 e 0.62 e 0.13 0.08In 0.002 b0.002 0.017 0.028 0.005 0.011 0.004 0.002 0.003 0.003 0.059 0.005 0.002–0.028 0.009 0.006 0.02 ⁎ 0.08 ⁎ 2.87 1.11La 0.49 0.58 5.08 6.74 1.71 2.98 0.85 1.18 1.65 1.63 5.06 2.60 0.49–6.74 2.386 1.710 ND ND 10.48 6.80Li 0.490 0.390 8.770 14.000 1.300 4.680 0.510 0.350 1.060 0.809 52.100 4.930 0.350–14.000 3.648 1.631 20 80 41.86 7.24Mn 15.30 10.10 12.50 12.50 18.60 15.20 63.30 91.10 34.80 34.60 42.90 24.30 10.10–91.10 29.770 22.502 100 510 72.90 35.84Mo 1.96 10.80 3.99 3.76 7.77 6.26 16.40 1.97 1.25 1.17 1.99 0.61 0.61–16.40 5.477 3.614 2.4 13 6.18 1.51Nb 0.22 0.10 1.74 3.22 0.65 2.65 0.35 0.35 0.67 0.70 5.66 1.93 0.10–3.22 1.188 0.712 1 5 20.58 4.22Nb(XRF) 3 2 4 3 2 4 3 b2 3 6 5 4 b2–4 3.42 3.22Ni 4.97 2.29 16.70 45.30 10.00 7.02 3.60 2.77 34.40 34.70 38.20 6.00 2.29–45.30 13.305 8.119 8 51 54.17 3.20

300D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306

Pb 1.34 0.68 4.45 16.80 3.81 4.94 2.45 0.73 13.20 12.80 10.80 3.72 0.68–16.80 5.212 3.200 2.5 53 11.10 3.47Rb 0.68 0.36 21.80 14.50 3.37 8.95 4.15 0.85 1.69 1.78 7.80 3.01 0.36–21.80 5.936 2.899 5 46 32.64 16.20Sb 0.15 0.14 0.34 0.53 0.17 0.15 0.16 0.10 0.22 0.23 0.59 0.14 0.10–0.53 0.210 0.185 0.5–2 ⁎ ND 0.80 0.35Sc 0.26 0.15 3.19 4.37 1.04 1.60 0.49 0.17 2.27 2.30 9.18 1.09 0.15–4.37 1.463 0.845 2 15 3.86 1.79Se 0.64 0.50 1.07 2.06 0.89 1.07 1.22 0.57 1.22 1.53 1.30 0.51 0.50–2.06 0.975 0.884 1 f 7.6 f 1.72 0.84Sn 0.24 0.29 0.69 1.12 0.31 0.55 0.50 0.23 0.26 0.27 2.25 0.61 0.23–1.12 0.480 0.419 1 4.1 1.90 1.11Sr 253.0 351.0 384.0 300.0 262.0 291.0 201.0 384.0 337.0 337.0 213.0 366.0 201.0–384.0 312.900 306.953 130 1100 206.82 99.18Sr(XRF) 220 283 359 354 255 298 225 447 284 227 260 279 220–447 300.4 293.8Ta 0.085 0.031 0.390 0.390 0.066 0.210 0.033 0.045 0.036 0.034 0.510 0.170 0.031–0.390 0.146 0.093 ND ND 16.38 1.20Te b0.005 0.007 0.046 0.054 0.007 0.008 b0.005 b0.005 b0.005 0.031 0.097 b0.005 0.007–0.054 0.024 0.016 ND ND 62.73 58.01Th 0.27 0.13 3.06 4.95 0.99 2.78 0.55 0.39 0.61 0.62 5.40 2.06 0.13–4.95 1.579 0.911 6.3 22 3.30 1.80Ti 44.8 21.4 555.0 885.0 129.0 294.0 70.3 49.8 88.4 89.9 2490.0 196.0 21.4–885.0 233.370 126.904 500 2600 ND NDTi(XRF) 50.0 20.0 600.0 1010.0 150.0 360.0 90.0 70.0 90.0 2910.0 2390.0 200.0 20.0–1010.0 264.00 143.53Tl 0.099 0.084 0.170 0.310 0.085 0.170 0.106 0.052 0.093 0.090 0.400 0.119 0.052–0.310 0.129 0.114 ND ND 1.72 0.65U 0.97 5.32 4.13 6.66 4.22 2.88 3.45 1.27 2.74 2.76 3.03 0.80 0.80–6.66 3.244 2.642 1–3 ⁎ ND 6.06 1.51V 2.71 3.20 32.50 50.20 15.90 19.30 12.70 2.89 12.90 13.60 117.00 8.72 2.71–50.20 16.102 10.601 23 120 37.28 15.04V(XRF) b5 b5 38 61 9 16 5 6 20 117 93 11 b5–61 32.17 17.04W 0.083 0.058 0.340 0.550 0.120 0.340 0.088 0.056 0.130 0.150 0.920 0.210 0.056–0.550 0.198 0.148 2–6 ⁎ ND 3.46 0.04Y 0.62 0.87 4.75 6.15 2.13 3.19 1.58 0.90 4.56 4.49 6.56 2.79 0.62–6.15 2.754 2.132 7 37 8.93 5.96Zn 3.53 5.51 18.70 21.40 12.20 9.00 7.95 7.78 13.70 14.60 55.10 12.30 3.53–21.40 11.207 9.885 18 100 75.54 11.07Zr 1.24 0.51 11.60 19.60 3.32 10.60 1.64 1.25 3.37 3.38 36.40 6.38 0.51–19.60 5.951 3.426 30 160 54.73 36.94Zr(XRF) b3 b3 18 37 9 19 5 6 7 76 65 8 b3–37 21.33 11.95Pr 0.130 0.150 1.270 1.810 0.500 0.790 0.270 0.270 0.530 0.540 1.490 0.630 0.130–1.810 0.635 0.461 ND ND 8.89 6.45Nd 0.520 0.610 4.960 7.040 2.030 3.130 1.150 1.040 2.260 2.330 5.780 2.440 0.520–7.040 2.518 1.848 ND ND 11.58 5.66Sm 0.120 0.130 1.050 1.540 0.490 0.690 0.310 0.200 0.660 0.640 1.300 0.520 0.120–1.540 0.571 0.423 0.4–4.4 7–22 2.80 1.16Eu 0.029 0.036 0.240 0.320 0.110 0.140 0.060 0.048 0.170 0.170 0.290 0.110 0.029–0.320 0.126 0.096 0.12–

0.52–5.4 0.39 0.20

Gd 0.150 0.220 1.110 1.560 0.530 0.750 0.330 0.220 0.810 0.830 1.270 0.520 0.150–1.560 0.620 0.483 ND ND 2.44 1.83Tb 0.019 0.022 0.170 0.240 0.079 0.120 0.057 0.033 0.130 0.130 0.220 0.076 0.019–0.240 0.095 0.070 0.06–

1.21–5.5 2.01 0.64

Dy 0.110 0.120 0.970 1.430 0.470 0.780 0.320 0.170 0.820 0.810 1.440 0.450 0.110–1.430 0.564 0.410 ND ND 1.94 1.24Ho 0.022 0.029 0.200 0.290 0.093 0.160 0.063 0.035 0.170 0.170 0.310 0.091 0.022–0.290 0.115 0.085 ND ND 0.88 0.48Er 0.067 0.076 0.600 0.900 0.260 0.490 0.210 0.110 0.460 0.480 0.960 0.260 0.067–0.900 0.343 0.250 ND ND 0.68 0.47Tm 0.009 0.010 0.088 0.130 0.036 0.075 0.034 0.016 0.063 0.064 0.160 0.035 0.009–0.130 0.050 0.036 ND ND 0.50 0.39Yb 0.058 0.069 0.590 0.880 0.240 0.530 0.220 0.100 0.390 0.420 1.050 0.230 0.058–0.880 0.331 0.235 0.9 5 0.78 0.51Lu 0.009 0.010 0.092 0.140 0.037 0.084 0.037 0.015 0.064 0.038 0.065 0.180 0.009–0.180 0.053 0.037 ND ND 0.70 0.22a For brown coal (lignite and subbituminous; Yudovich et al., 1985).b Bouška and Pešek (1999).c For brown coals (Yudovich and Ketris, 2006b).d For lignites (Yudovich and Ketris, 2005a).e In coal regardless of rank (0.1); on an ash basis for lower rank (0.62; Yudovich and Ketris, 2005b).f For brown coals (Yudovich and Ketris, 2006a).⁎ Regardless of rank (Yudovich et al., 1985).

301D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306


coals are characterised by occurrence of ββ- and αβ-typehopanes from C27 to C31; C28 is absent. The predominanthopane in most of the samples is hop-17(21)-ene (Fig. 8a),which has been found in many sediments and coals. Someresearchers suggest direct bacterial contribution of thiscompound (Ourisson et al., 1979; Volkman et al., 1986;Wakeham, 1990), but it is also proposed to be a diageneticproduct of hop-22(29)-ene (Brassell et al., 1980), whichmight originate from diplopterol. Diplopterol has beenfound in several eukaryotic phyta, such as ferns, mosses,lichens and fungi, but also in hopanoid producing bacteria(Ourisson et al., 1979). In the sample with a predominanceof n-C24 (Soko 8), the dominant hopane was C2917α(H)21β(H)-norhopane (Fig. 8c). The high content ofC3117α(H)21β(H)-homohopene found in sample Soko 6(Fig. 8b) may indicate stronger reducing conditions andstrong bacterial decomposition.

The type and abundance of the hopanes detected inthe Soko Banja coal implies bacterial activity and alsoindicates an immature to early mature stage of the organicmatter or diagenetic alteration of the biomass, which wasconfirmed by the huminite reflectance (Table 1).

Steranes are found in low concentrations in the coalswith high terrigenous inputs. They are commonlyidentified by m/z 217 in mass fragmentograms. Steraneswere detected in low amounts in the saturated hydrocar-bon fractions of the SokoBanja coals. The predominanceof the C29 homologues over the C27 ones indicates aterrigenous contribution (Huang andMeinschein, 1979).

4.6. Inorganic geochemistry

The measured concentrations of the major and traceelements in Soko Banja coal are presented in Table 4. Thecoal shows enrichment in F, Sr, Mo, Pb, Ni, As and Cucompared to the Clarke value (Yudovich et al., 1985;Yudovich and Ketris, 2005a). In comparison with worldlignites (Bouška and Pešek, 1999), using the geometricmean value, coal from the Soko Banja basin has a higherstrontium content. Slightly higher values than in theworldlignites were obtained for Mo, Ni, Se, U and W. The lowboron content (10–37 mg/kg) confirms that the SokoBanja coals were formed in a fresh water environment(Goodarzi and Swaine, 1994).

Summarising the affinities of the major and traceelements against the ash content and maceral analyses,the following conclusions can be drawn:

1. Elements showing inorganic affinity are: Al, Si, Fe,Mg,K, Na, Cl, P, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Ga, Ge,Hf, In, Li, Nb, Ni, Pb, Rb, Sc, Se, Sn, Te, Ti, Tl, V,W, Y,Zn, Zr, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sm, Eu, and Gd,

2. Elements showing organic affinity are: S (strong) andMo (slight).

Most of major elements (Si, Ti, Al, Mg, Na and K) andtrace elements (Ba, Be, Bi, Cr, Cs, Cu, Ga, Ge, Hf, In, La,Li, Nb, Ni, Sb, Sc, Sn, Ta, Te, Ti, Tl, V, W, Y, Zn and Zr)correlate well with alumosilicate (clay minerals andfeldspars). Ca (r=+0.93) and Mn (r=+0.86) show goodcorrelationwith carbonates,which complywith Finkelman(1994). Strontium analysed by the XRF method (SrXRF;Table 4) has a relatively good correlation with carbonates(r=+0.62), while strontium analysed by the ICP-MSmethod (Sr; Table 4) shows poor correlation (r=+0.26).The highest values of Sr andMnwere determined inmatrixcoal from the central part of theMain seam in sample Soko7/2, which also has the highest Ca content (Table 4; Fig. 9).According to this, it seems that enrichment of the Srcontent in coal is related to carbonate rocks. The totalabsence of a correlation between Ca and Mg (r=−0.13)means that Mg is not related to dolomite, but mostprobably to clay or mica minerals. The pyrite content hasno positive correlation to any major or trace element.

Several potentially toxic trace elements, such as As,Cr, Cu, Ni and Se, exhibit their highest value in matrixcoal, but only from the upper part of the seam (Fig. 9),while matrix coal from the central part of the seam has alower content. The higher content of Mo was detected inxylite-rich coal from the central and partly from upperpart of seam, but not in the lower part. It seems thatlithotypes are not an important factor influencing thecontent of these elements in the Soko Banja coals.

The content of some elements, such as Ti, V, Zr andNb, varied considerably when analysed by both appliedmethods. This is, apparently, related to specific coal faciesin which mineral-bituminous groundmass was formed asa product of strong bacterial decomposition in anenvironment rich in CaCO3. The highest variations wererecorded in samples rich in mineral-bituminous ground-mass. Although quite aggressive, the digestion methodused for ICP-MSwas not able decompose the bituminousgroundmass which would enable the dissolution of all Ti,V, Zr and Nb from the mineral-bituminous groundmass,or inorganic components captured by the bituminousmaterial. A good example for this was the high correlationbetween clay and Zr (r=+0.92) analysed by the ICP-MSmethods but no correlation at all between the mineral-bituminous groundmass and Zr (r=+0.06). This meansthat only a small amount of Zr was dissolved, while the Zrfrom the mineral-bituminous groundmass was notaffected by the dissolution method. This was alsoobserved on analysed samples of clay from other Serbiancoal deposits (Simić and Životić, unpublished results).

Fig. 9. Macropetrographic profile of the Soko Banja coal and vertical distribution of the contents of calcium, boron, strontium, chromium, nickel, molybdenum and selenium in Soko Banja coal.

303D.Ž

ivotićet

al./International

Journalof

Coal

Geology

73(2008)

285–306


5. Conclusions

The coals from the Soko Banja basin were formedin a fresh water, calcium-rich deposition environment.Petrographic analyses of coal from the main seam of theSoko Mine show that the humic coals have a highcontent of huminite, a relatively low content of liptiniteand a low content of inertinite. The most abundantmacerals of the huminite group are ulminite, densiniteand gelinite and of the liptinite group, sporinite, resinite,liptodetrinite, suberinite, and cutinite. Inertodetrinite,funginite and fusinite are the most common macerals ofthe inertinite group. Clay dominates in the mineralmatter, while carbonates, pyrite and mineral-bituminousgroundmass are less abundant.

The composition of biomarker implies that the coal-forming plants in the Soko Banja basin were mostlygymnosperms (conifers), but that a contribution ofangiosperms cannot be excluded.

High CPI values with a predominance of long-chainn-alkanes and a maximum at n-C29 in the lower andcentral part of the main coal seam are consistent withhigher terrestrial plants, probably angiosperm leaves,being the origin. A higher abundance of mid-chain n-alkanes, with a domination of n-C24, may indicate thepresence of epicuticular waxes from cone and shoots offossil conifer species (e.g. Pinus). The domination orpredominance of abietane type in the upper part of theMain coal seam suggests a high contribution ofgymnosperms to the formation of the Soko Banjacoals. Variations in the pristane/phytane ratio in the coalfrom the Soko Banja basin could be interpreted asreflecting changes in the redox conditions, but abacterial origin of phytane cannot be excluded.

The type and abundance of hopane detected in theSoko Banja coals imply bacterial activity and also animmature to early mature stage of the organic matter or adiagenetic alteration of the biomass, which wasconfirmed by reflectance measurements of huminite.

The first results on the contents of major and traceelements in the Soko Banja coal revealed that incomparison with world lignites (using the geometricmean value), the Soko Banja coal has a higher strontiumcontent. Slightly higher values than in the world ligniteswere obtained for Mo, Ni, Se, U and W. In comparisonwith the Clarke value, the Soko Banja coal showsenrichment in F, Sr, Mo, Pb, Ni, As and Cu. Correlationanalysis showed inorganic affinity for almost all themajor and trace elements, with the exception of S, whichhas an organic affinity.

The content of some elements, such as Ti, V, Zr andNb, varied considerably when analysed by both the

applied methods (XRF, ICP-MS). The digestion methodused for ICP-MS was probably inadequate for thedissolution of all the Ti, V, Zr and Nb from the mineral-bituminous groundmass, or inorganic components.

Acknowledgements

This project was partly financed by the Ministry ofScience and Environmental Protection of Serbia (projectno. 146008), which is gratefully acknowledged. We arealso grateful to Dr. A. Bechtel, Dr. I. Kostova-Dineva andDr. J.C. Hower whose critical comments have greatlybenefited this paper.

References

Allen, J.E., Fornery, F.W., Markovetz, A.J., 1971. Microbialdegradation of n-alkanes. Lipids 6, 448–452.

Alexander, G., Hazai, I., Grimalt, J., Albaiges, J., 1987. Occurrenceand transformation of phyllocladane in brown coals from NogradBasin, Hungary. Geochim. Cosmochim. Acta 51, 2065–2073.

Bechtel, A., Gruber, W., Sachsenhofer, R.F., Gratzer, R., Püttmann,W.,2001.Organic geochemical and stable carbon isotopic investigationof coals formed in low-lying and raised mires within the EasternAlps (Austria). Org. Geochem. 32, 1289–1310.

Bechtel, A., Sachsenhofer, R.F., Gratzer, R., Lücke, A., Püttmann, W.,2002. Parameters determining the carbon isotopic composition ofcoal and fossil wood in the Early Miocene Oberdorf lignite seam(Styrian Basin, Austria). Org. Geochem. 33, 1001–1024.

Bechtel, A., Gruber, W., Sachsenhofer, R.F., Gratzer, R., Lücke, A.,Püttmann, W., 2003a. Depositional environment of the LateMiocene Hausruck lignite (Alpine Foreland Basin): insights frompetrography, organic geochemistry, and stable carbon isotopes. Int.J. Coal Geol. 53, 153–180.

Bechtel, A., Sachsenhofer, R.F., Markic, M., Gratzer, R., Lücke, A.,Püttmann, W., 2003b. Paleoenvironmental implications frombiomarker and stable isotope investigations on the PlioceneVelenje lignite seam (Slovenia). Org. Geochem. 34, 1277–1298.

Bechtel, A., Markic, M., Sachsenhofer, R.F., Jelen, B., Gratzer, R.,Lücke, A., Püttmann, W., 2004. Paleoenvironment of the upperOligocene Trbovlje coal seam (Slovenia). Int. J. Coal Geol. 57,23–48.

Bechtel, A., Sachsenhofer, R.F., Zdravkov, A., Kostova, I., Gratzer, R.,2005. Influence of flora assemblage, facies and diagenesis onpetrography and organic geochemistry of the Eocene Burgas coaland the Miocene Maritza-East lignite (Bulgaria). Org. Geochem.36, 1498–1522.

Bouška, V., Pešek, J., 1999. Quality parameters of lignite of the NorthBohemian Basin in the Czech Republic in comparison with theworld average lignite. Int. J. Coal. Geol. 40, 211–235.

Brassell, S.C., Comet, P.A., Eglinton, G., Isaacson, P.J., McEvoy, J.,Maxwell, J.R., Thompson, I.D., Tibbetts, P.J.C., Volkman, J.K.,1980. The origin and fate of lipids in the Japan Trench. In:Douglas, A.G., Maxwell, J.R. (Eds.), Advances in OrganicGeochemistry. Pergamon Press, Oxford, pp. 375–392.

Bray, E.E., Evans, E.D., 1961. Distribution on n-paraffins as a clueto recognition of source beds. Geochim. Cosmochim. Acta 22, 2–15.

Cranwell, P.A., 1977. Organic geochemistry of Cam Loch (Suther-land) sediments. Chem. Geol. 20, 205–221.


Cranwell, P.A., Eglinton, G., Robinson, N., 1987. Lipids of aquaticorganisms as potential contributors to lacustrine sediments, II. Org.Geochem. 11, 513–525.

Dehmer, J., 1989. Petrographical and organic geochemical investiga-tion of Obrerpfalz brown coal deposit, West Germany. Int. J. CoalGeol. 11, 273–290.

Dehmer, J., 1995. Petrological and organic geochemical investigationof recent peats with known environments of deposition. Int. J. CoalGeol. 28, 111–138.

Diessel, C.F.K., 1986. The correlation between coal facies anddepositional environments. Advances in the Study of the SydneyBasin, Proc. 20th Symp. Univ. Newcastle, pp. 19–22.

Dolić, D., 1998. The relationship of Paratethyan and Miocene lakedeposits of Serbia. 13th Conference of Geologists of Yugoslavia,book II, pp. 373–381.

ECE-UN, 1998. Economic Commission for Europe, Committee onSustainable Energy— United Nations. International Classificationof in-Seam Coals. Energy 19 (41 pp.).

ECE-UN, 1999. Economic Commission for Europe, Committee onSustainable Energy — United Nations. International CodificationSystem for Low-Rank Coals. Energy 9 (19 pp.).

ECE-UN, 2000. Economic Commission for Europe, Committee onSustainable Energy— United Nations. International Classificationfor Low-Rank Coals. Energy 12 (21 pp.).

Eglinton, G., Hamilton, R.J., 1967. Leaf epicuticular waxes. Science156, 1322–1335.

Ercegovac, M., 1998. First Proposal of the Classification and theCodification of the Low-Rank Coals of Serbia. Universityof Belgrade, Faculty of Mining and Geology, Belgrade. 143 pp. (inSerbian).

Ercegovac, M., Pulejković, D., 1991. Petrographic composition andcoalification degree of coal in the Kolubara Coal Basin. AnnalesGeol. de la penin. Balkanique, Belgrade, vol. 55/2, pp. 223–239.

Ercegovac, M., Životić, D., Kostić, A., 2006. Genetic-industrialclassification of brown coals in Serbia. Int. J. Coal Geol. 68, 39–56.

Finkelman, R.B., 1994. Modes of occurrence of potentially hazardouselements in coal: levels of confidence. Fuel Process. Technol. 39,21–34.

Gagić, D., in press. Collective accidents, state of safety and technicalprotection in underground mines in Serbia. Faculty of Miningand Geology, Belgrade, Fund of Technical Documentation(in Serbian), 411 pp.

Giger, W., Schaffner, C., 1977. Aliphatic, olefinic and aromatichydrocarbons in recent sediments of a highly eutrophic lake. In:Campos, R., Goni, J. (Eds.), Advances in Organic Geochemistry,1975. Pergamon, Oxford, pp. 375–390.

Goodarzi, F., Swaine, D.J., 1994. Paleoenvironmental and environ-mental implications of the Boron content of coals. Geol. Surv. Can.Bull. 471 (76 pp.).

Hagemann, H.W., Hollerbach, A., 1979. Relationship between themacropetrographic and organic geochemical composition of lignites.In: Douglas, A.G., Maxwell, J.R. (Eds.), Adv. Org. Geochem.Pergamon, London, pp. 631–638.

Huang, W.-Y., Meinschein, W.G., 1979. Sterols as ecologicalindicators. Geochim. Cosmochim. Acta 43, 739–745.

Kalkreuth, W., Keuser, C., Fowler, M., Li, M., McIntyre, D.,Püttmann, W., Richardson, R., 1998. The petrology, organicgeochemistry and paleontology of Tertiary age Eureka SoundGroup coals, Arctic Canada. Int. J. Coal Geol. 29, 799–809.

Markic, M., Sachsenhofer, R.F., 1997. Petrographic composition anddepositional environments of the Pliocene Velenje lignite seam(Slovenia). Int. J. Coal Geol. 33, 229–254.

Marović, M., Đoković, I., Đinović, D., 1990. Neotectonic frameworkof Soko Banja Basin and its margin. Annales Geol. de la penin.Balkanique 54, 145–150.

Matsumoto, G.I., Akiyama, M., Watanuki, K., Torii, T., 1990. Unusualdistribution of long-chain n-alkanes and n-alkenes in Antarcticsoil. Org. Geochem. 15, 403–412.

Meier, A.L., Lichte, F.E., Biggs, P.H., Bullock, J.J., 1996. Analysis of coalash by inductively coupled plasma-mass spectrometry: analyticalmethods for themineral resources surveys program. In: Arbogast, B.F.(Ed.), U.S. Geol. Surv. Open File, 96–525, pp. 109–125.

Meyers, P.A., Ishiwatari, R., 1993. Lacustrine organic geochemistry—an overview of indicators of organic matter sources and diagenesisin lake sediments. Org. Geochem. 20, 867–900.

Meyers, P.A., Lallier-Vergés, E., 1999. Lacustrine sedimentary organicmatter records of Late Quaternary paleoclimates. J. Paleolimnol.21, 345–372.

Milićević, Z.M., Šaban, M.M., Jovančićević, B.S., Nedeljković, J.M.,1996. GC–MS in organic geochemistry of coal-estimation of theorigin and degree of carbonification in coal from the Kosovo basin.J. Serb. Chem. Soc. 61, 823–830.

Ming, Q., Xilin, R., Dayhong, T., Jian, X., Wolf, M., 1994. Petrographicand geochemical characterization of pale and dark brown coal fromYunnan Province, China. Int. J. Coal Geol. 25, 65–92.

Nikolić, P., Maksimović, B., 1990. Structural Fabric of Soko coaldeposit (Eastern Serbia). Annales Geol. de la penin. Balkanique54, 76–80.

Novković, M., Milaković, B., Cvetković, D., 1975. The Soko BanjaBasin. In: Aksin, V., Maksimović, B. (Eds.), The Geology ofSerbia, Fossil Fuels, VII, Belgrade, pp. 130–135 (in Serbian).

Otto, A., Simoneit, B.R.T., 2001. Chemosystematics and diagenesis ofterpenoids in fossil conifer species and sediment from the EoceneZeitz Formation, Saxony, Germany. Geochim. Cosmochim. Acta65, 3505–3527.

Otto, A., Wilde, V., 2001. Sesqui-, di- and triterpenoids as chemosyste-matic markers in extant conifers—a review. Bot. Rev. 67, 141–238.

Otto, A., Walther, H., Püttmann, W., 1995. Molecular composition of aleaf- and root bearing Oligocene oxbow Lake Clay, WeisselsterBasin, Germany. Org. Geochem. 22, 275–286.

Otto, A., Walther, H., Püttmann, W., 1997. Sesqui- and diterpenoidbiomarkers preserved in Taxodium-rich Oligocene oxbow lakeclays, Weisselster Basin, Germany. Org. Geochem. 26, 105–115.

Otto, A., Simoneit, B.R.T., Wilde, V., Kunzmann, L., Püttmann, W.,2002. Terpenoid composition of three fossil resins from Cretaceousand Tertiary conifers. Rev. Palaeobot. Palynol. 120, 203–215.

Otto, A., Simoneit, B.R.T., William, R.C., 2003. Resin compoundsfrom the seed cines of three fossil conifer species from the MioceneClarkia flora, Emerald Creek, Idaho, USA, and from related extantspecies. Rev. Palaeobot. Palynol. 126, 225–241.

Otto, A., Simoneit, B.R.T., Rember, W.C., 2005. Conifer andangiosperm biomarker in clay sediments and fossil plants fromthe Miocene Clarkia Formation, Idaho, USA. Org. Geochem. 36,907–922.

Ourisson, G., Albrecht, P., Rohmer, M., 1979. The hopanoidspaleochemistry and paleobiochemistry of a group of naturalproducts. Pure Appl. Chem. 51, 709–729.

Papanicolaou, C., Dehmer, J., Fowler, M., 2000. Petrological andorganic geochemical characteristics of coal samples from Florina,Lava, Moschopotamos and Kalavryta coal fields, Greece. Int. J.Coal Geol. 44, 267–292.

Peters, E.K., Moldowan, M.J., 1993. The biomarker guide, interpretingmolecular fossils in petroleum and ancient sediment. Prentice Hall,New Jersey.


Philp, R.P., 1985. Fossil Fuel Biomarkers: Applications and Spectra.Methods in Geochemistry and Geophysics, vol. 23. Elsevier. 294 pp.

Püttmann, W., Bracke, R., 1995. Extractable organic compounds in theclay mineral sealing of a waste disposal site. Org. Geochem. 23,43–54.

Rögl, F., 1996. Stratiographic correlation of the Paratethys Oligoceneand Miocene. Mitt. Ges. Geol. Bergbaustud. Österr. 41, 65–73.

Simić, V., 1958. Die Entwicklung der Kohlengrube und Kohlen-wirtschaft in Serbien. Serb. Akad. Wissen., Sonderausgabe CCCder Math.-Naturwissen. Klasse 18, Belgrad. 309 pp. (In Serbian).

Simoneit, B.R.T., Grimalt, J.O., Wang, T.G., Cox, R.E., Hatcher, P.G.,Nissenbaum, A., 1986. Cyclic terpenoids of contemporaryresinous plant detritus and of fossil woods, amber and coal. Org.Geochem. 10, 877–889.

Stefanova, M., 2004. Molecular indicators for Taxodium dubium ascoal progenitor of “Chukurovo” lignite, Bulgaria. Bull. Geolog.Soc. Greece XXXVI, 342–347.

Stefanova, M., Magnier, C., Velinova, D., 1995. Biomarker assem-blage of some Miocene-aged Bulgarian lignite lithotypes. Org.Geochem. 23, 1067–1084.

Sykorova, I., Pickel, W., Christanis, K., Wolf, M., Taylor, G.H., Flores,D., 2005. Classification of huminite-ICCP System 1994. Int.J. Coal Geol. 62, 85–106.

Taylor, G.H., Teichmüller, M., Davis, A., Diessel, C.F.K., Littke, R.,Robert, P., 1998. Organic Petrology. Gebrüder Borntraeger, Berlin.704 pp.

Teichmüller, M., 1989. The genesis of coal from the viewpoint of coalpetrology. Int. J. Coal Geol. 12, 1–87.

tenHaven, H.L., de Leeuw, J.W., Rullkötter, J., SinningheDamste, J.S.,1987. Restricted utility of the pristane/phytane ratio as apaleoenvironmental indicator. Nature 330, 641–643.

Tissot, B.T., Welte, D.H., 1984. Petroleum Formation and Occur-rences, 2nd ed. Springer, Berlin. 699 pp.

Tyson, R.V., 1995. Sedimentary Organic Matter. Chapman & Hall,London. 615 pp.

Volkman, J.K., Allen, D.I., Stevenson, P.L., Burton, H.R., 1986.Bacterial and algal hydrocarbons from a saline Antarctic lake. AceLake. Org. Geochem. 10, 671–681.

Wakeham, S.G., 1990. Algal and bacterial hydrocarbons in particulatematerial and interfacial sediment of the Cariaco-Trench. Geochim.Cosmochim. Acta 54, 1325–1336.

Wakeham, S.G., Schaffner, C., Giger, W., 1980. Polycyclic aromatichydrocarbons in Recent lake sediments. II. Compounds derivedfrom biological precursors during early diagenesis. Geochim.Cosmochim. Acta 44, 415–429.

Wang, T.-G., Simoneit, B.R.T., 1990. Organic geochemistry and coalpetrology of Tertiary brown coal in the Zhoujing mine, BaiseBasin, South China. 2. Biomarker assemblage and significance.Fuel 69, 12–20.

Welte, D.H., Waples, O.W., 1973. Über die Bevorzugung geradzahli-ger n-Alkane in Sedimentgesteinen. Naturwissenschaften 60,516–517.

Yudovich, Ya.E., Ketris, M.P., 2005a. Arsenic in coal: a review. Int. J.Coal Geol. 61, 141–196.

Yudovich, Ya.E., Ketris, M.P., 2005b. Mercury in coal: a review. Part1. Geochemistry. Int. J. Coal Geol. 62, 107–134.

Yudovich, Ya.E., Ketris, M.P., 2006a. Selenium in coal: a review. Int.J. Coal Geol. 67, 112–126.

Yudovich, Ya.E., Ketris, M.P., 2006b. Chlorine in coal: a review. Int. J.Coal Geol. 67, 127–144.

Yudovich, Y., Ketris, M., Mertz, A., 1985. Trace Elements in Coals.Nauka, Leningrad. 239 pp. (in Russian).

Životić, D., Jelenković, R., Gržetić, I., Simić, V., 2005. Preliminarystudy of potentially toxic trace elements in the Soko mine coal(Eastern Serbia). Geol. Maced. 19, 83–88.

petrological, organic geochemical and geochemical characteristics of coal from the soko mine, serbia

Documents