pliocene lignites from apofysis mine, amynteo basin, northwestern
TRANSCRIPT
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International Journal of Coal Geology 54 (2003) 57–68
Pliocene lignites from Apofysis mine, Amynteo basin,
Northwestern Greece: petrographical characteristics and
depositional environment
A. Iordanidis*, A. Georgakopoulos
Department of Mineralogy-Petrology-Economic Geology, School of Geology, Aristotle University of Thessaloniki,
GR-54006 Thessaloniki, Greece
Abstract
Coal petrological investigation along with proximate and elemental analyses were undertaken to determine the
petrographic characteristics of the Apofysis lignites (Amynteo basin, Northwestern Greece) and their depositional
environment. Eight samples (representing different lignite beds of the Apofysis deposit) were collected from a borehole.
The Apofysis lignites have an Eu-ulminite B reflectance of Rr = 0.22%, and in terms of lithotype belong to matrix soft
brown coals. Huminite is the most abundant maceral group and consists mostly of humodetrinite. Inertinite has relatively
low percentages whereas liptinite concentrations are low in the lower lignite beds and higher in the upper ones. Ternary
plots and facies indices were employed in order to investigate the palaeoenvironment. The depositional environment of the
Apofysis lignites is not definitely ascribed to a forest swamp or a reed marsh environment. The high ash content of the
analysed samples is a clear indication of a topogenous setting. Low tissue preservation index (TPI) and high gelification
index (GI) values are observed. High alkalinity and strongly reducing conditions may be inferred from the presence of
syngenetic (framboidal) pyrite, the low TPI values which indicate high bacterial activity, and thus high pH conditions, and
the preservation of gastropod shells and chlorophyllinite. High GI indicates a constant influx of calcium-rich waters into
the coal swamp. The Apofysis lignite deposit may be interpreted to be autochthonous to hypoautochthonous. The peat
accumulation was governed by a high groundwater level (wet telmatic to limno-telmatic facies) and a moderate subsidence
rate.
D 2003 Elsevier Science B.V. All rights reserved.
Keywords: Coal petrology; Depositional environment; Lignites; Amynteo; Ptolemais; Greece
1. Introduction
Most Greek lignite deposits are located in the
Florina–Ptolemais–Kozani basin, a large inten-
0166-5162/03/$ - see front matter D 2003 Elsevier Science B.V. All right
doi:10.1016/S0166-5162(03)00019-3
* Corresponding author. Tel.: +30-31-998-459; fax: +30-31-
998-568.
E-mail address: [email protected] (A. Iordanidis).
sively exploited area, in Northern Greece. This area
is exploited by opencast mining and feeds nearby
lignite-fired power stations. The contribution of
lignite to the total electric power output of the
country exceeds 75%. Several studies have been
published on the petrography of Greek lignites, but
few works have been carried out for the Ptolemais
area (Cameron et al., 1984; Kaouras, 1989; Fowler
et al., 1991; Antoniadis, 1992; Antoniadis et al.,
s reserved.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–6858
1994; Valceva et al., 1995; Antoniadis and Lamp-
ropoulou, 1995; Antoniadis and Rieber, 1997;
Kalaitzidis et al., 1998, 2000; Georgakopoulos and
Fig. 1. Simplified geological map of the Florina–Ptolemais–Koza
Valceva, 2000). In particular, no detailed and sys-
tematic coal petrographic investigations have been
carried out for the Amynteo area. The present work
ni basin, showing the location of the Apofysis lignite mine.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–68 59
aims to study the vertical differentiation in petro-
graphic characteristics of Apofysis lignites and
make a broad estimation of the depositional envi-
ronment.
2. Geologic setting
The elongated intermontaine Florina–Ptolemais–
Kozani basin is a NNW–SSE trending graben
system that extends over a distance of 250 km
from Bitola, in the Former Yugoslavian Republic of
Macedonia to Servia, southeast of Kozani, Greece.
The basement consists of metamorphic schists in
the west and crystalline limestone in the east. The
Amynteo basin is part of this graben that opened in
the late Miocene and was divided into sub-basins in
the Pleistocene (Pavlides and Mountrakis, 1986).
The Apofysis opencast lignite mine is situated 700
m above sea level at the southwestern margins of
the Amynteo coal-bearing basin and covers a sur-
face area of 4.4 km2 (Fig. 1). The Apofysis
deposits consist of rythmic alterations of lignite
beds and lacustrine and fluvial sediments (Koukou-
zas et al., 1981).
Fig. 2. Simplified stratigraphic column of the drilled section of the
Apofysis lignite deposit, showing the sampling intervals.
3. Sampling and analytical methods
Eight lignite samples were collected from a
borehole located in the central part of the Apofysis
mine. Since the Apofysis deposit is a complex
succession of lignite beds and interbedded clastic
materials, only lignite beds thicker than 50 cm were
chosen for sampling. Lignite beds are located in the
depth interval between 50 and 100 m. A simplified
stratigraphic column of the Apofysis lignite deposit
showing the sampling intervals is shown in Fig. 2.
The depth of sampling is also shown in Table 1.
For proximate and ultimate analysis an aliquot of
each sample was ground to < 100 mesh and
analysed following the procedures outlined by
DIN (Deutsches Institut fur Normung-DIN, 1995,
1978). Sulphur was determined using a LECO SC-
144DR analyzer. Carbon, hydrogen and nitrogen
were determined using a LECO CHN-2000 ana-
lyzer. Total organic carbon (TOC) was analyzed
using a LECO CR-12 carbon determinator. Pol-
ished blocks were prepared for maceral analysis
and Eu-ulminite B reflectance measurements (ran-
dom). At least 300 points were counted in
reflected white light in order to determine the
content of huminite and inertinite macerals, as well
as the mineral matter and pyrite contents. For the
determination of liptinite maceral content, the
count was repeated in fluorescence mode. The
combination of the two modes gave a complete
maceral analysis based on a total of more than
600 points. Maceral subgroups were determined for
the huminite group. The samples were also macro-
scopically described according to the classification
Table 1
Proximate and ultimate analyses of Apofysis lignite samples, as well as lithotype determination
Sample
ID
Depth
(m)
Moisture
(ad) %
Ash
(ad) %
Ash
(db) %
C
(daf) %
H
(daf) %
N
(daf) %
O
(daf) %
S
(daf) %
S +O
(daf) %
Lithotypes
A129 58.9 16.1 9.3 11.1 57.6 4.6 0.8 34.2 2.8 37.0 stratified-brown
A139 64.3 22.5 39.2 50.6 41.9 3.5 1.3 50.8 2.5 53.3 friable-unstratified-
brown
A144 67 22.1 24.3 31.2 55.0 5.4 1.6 nd nd 38.0 stratified-brown
A152 71 17.8 15.2 18.5 57.3 4.6 1.5 nd nd 36.6 stratified-black
A158 75 23.7 21.2 27.8 58.6 4.1 1.9 32.7 2.7 35.4 unstratified-black
A167 82.6 22.3 11.6 14.9 58.9 5.0 1.5 nd nd 34.6 stratified-black
A171 85 18.9 31.4 38.7 54.1 4.4 1.9 37.9 1.7 39.7 stratified-brown
A173 87 15.9 22.5 26.8 66.8 3.1 2.1 nd nd 28.0 stratified-black
nd = not determined; ad = air-dried basis; db = dry basis; daf = dry ash-free basis.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–6860
system for lithotypes of soft brown coals adopted
by ICCP (1993).
4. Results and discussion
The moisture, ash and total sulphur contents
together with the results of ultimate analysis are
summarized in Table 1. TOC measurements and
maceral composition along with mineral matter and
pyrite contents are shown in Table 2. Random
vitrinite reflectance measurements on Eu-ulminite B
in two samples (a total of 100 counts) gave a mean
value of 0.22% (F 0.02) Rrandom in both samples, a
value that suggests a transition from peat to lignite.
TOC ranges from 63.8% up to 71.0% (daf). Carbon
ranges from 41.9% to 66.8% (daf), hydrogen from
3.1% up to 5.4% (daf) and nitrogen from 0.8% to
2.1% (daf).
According to the terminology and descriptions
recommended by the International Committee for
Coal and Organic Petrology (ICCP, 1993), the Apof-
ysis lignites belong to matrix coal with an obvious
vertical differentiation in colour and stratification, as
shown in Table 1. Brown (weakly gelified) and
brownish black (more strongly gelified) coal litho-
types are consistent through out the lithostratigraphic
section. The dark, more gelified coal may be the
product of anaerobic processes, while the pale coal,
generally formed by strong decay, may reveal more
or less aerobic conditions. However, according to
Hagemann and Wolf (1987), the light and dark
lignite bands result mainly from different degrees
of plant decompositions.
Huminite is the most abundant maceral group
(71.9–90.8 vol.%, mmf) and consists mostly of
humodetrinite [except sample A173 where humocol-
linite (Fig. 3a and b) is more abundant and sample
A167 where humotelinite is more abundant], while
inertinite has relatively low percentages (up to 14
vol.%, mmf) and liptinite shows low contents in the
lower lignite beds but higher concentrations (up to
25.7 vol.%, mmf) in the upper lignite beds. Character-
istic maceral types are shown in microphotographs of
Apofysis lignites in Figs. 3 and 4. The relative
abundance of maceral groups and mineral matter is
represented in ternary plots (Fig. 5). Although mac-
erals of the humodetrinite subgroup (i.e. attrinite and
densinite) are not analysed separately, it is observed
that both macerals contribute equally to the maceral
composition of the studied coals (Fig. 3c–e). Genesis
of humodetrinite may be attributed to relatively aero-
bic conditions (Teichmuller et al., 1998b). The Apof-
ysis mine is situated at the margins of the Amynteo
coal-bearing basin (i.e. at the margins of the precursor
peat mires), and at the margin of a peat bed, there is
greater prevalence of the physical breakdown of peat
to particulate matrix (Kuder et al., 1998), thus the
prevalence of humodetrinite. Attrinite and densinite
are also the principal constituents of peats and brown
coals from treeless marshes. It is considered that
‘coniferous-forest coals’ display better preservation
and larger sizes of cellular tissues (humotelinites) than
the ‘angiosperm-forest coals’, and also that reed peats
and reed brown coals (i.e. deposits of poorly lignified
and relatively cellulose-rich plants) consist mainly of
humodetrinite (Cameron et al., 1984; Teichmuller et
al., 1998b). However, the general assumption that
Table
2
Totalorganic
carbon(TOC)contents(w
t.%),maceral
andmineral
mattercontents(vol.%)andcalculatedfacies
indices
oflignitesamplesfrom
theApofysismine
Sam
ple
TOC
Huminitevol.%
(mmf)
Inertinitevol.%
(mmf)
Liptinitevol.%
(mmf)
Mineral
matter
Faciesindices
ID(daf)
%Htel
Hdet
Hcol
SHum
Fus
Sfus
Idet
Scle
SIner
Cut
Spor
Fluo
Res
Chlo
Lipd
Sub
SLip
MM
Pyr
TPI
GI
GWI
VI
A129
66.4
34.7
47.1
0.0
81.7
0.0
0.0
6.6
0.0
6.6
4.4
0.2
0.6
0.0
0.2
6.2
0.0
11.7
18.8
3.5
0.6
12.4
1.9
0.5
A139
63.8
10.3
60.8
0.8
71.9
1.6
0.0
0.8
0.0
2.4
8.0
0.4
2.5
4.2
1.7
8.9
0.0
25.7
52.6
2.3
0.2
30.2
11.1
0.2
A144
67.0
29.2
44.9
6.8
80.8
2.1
0.4
2.1
0.0
4.5
6.2
1.1
3.7
0.5
0.0
3.0
0.2
14.6
12.4
2.8
0.6
17.8
2.2
0.5
A152
68.4
7.8
65.5
4.6
77.9
4.3
0.5
1.6
0.0
6.5
2.3
1.2
2.6
0.9
0.3
8.4
0.0
15.6
30.8
2.7
0.2
12.0
12.9
0.2
A158
71.0
23.9
45.8
5.2
75.0
3.6
1.6
6.2
0.3
11.8
4.8
1.0
2.7
0.3
0.0
4.4
0.0
13.3
41.2
2.2
0.5
6.4
3.9
0.5
A167
70.3
64.5
19.5
6.5
90.6
1.1
0.0
1.1
0.0
2.2
1.1
1.7
0.6
2.8
0.0
1.1
0.0
7.3
10.7
2.8
2.4
41.8
0.6
2.7
A171
65.8
4.9
71.3
5.6
81.8
7.0
0.7
6.3
0.0
14.0
0.0
0.0
0.0
2.1
0.0
1.4
0.7
4.2
29.1
1.5
0.2
5.9
21.7
0.2
A173
68.5
32.0
19.2
39.5
90.8
1.1
0.0
1.6
0.0
2.7
3.8
1.6
0.0
1.1
0.0
0.0
0.0
6.6
8.4
3.3
0.5
34.0
2.1
1.3
daf=dry-ash
free;mmf=mineral
matterfree
basis;Htel=
humotelinite;
Hdet=humodetrinite;
Hcol=
humocollinite;
SHum=totalhuminite;
Fus=fusinite;
Sfus=Sem
ifusinite;
Idet=inertodetrinite;
Siner=totalinertinite;
Cut=
cutinite;
Spor=sporinite;
Fluo=fluorinite;
Res=resinite;
Chlo=chlorophyllinite;
Lipd=liptodetrinite;
Sub=suberinite;
SLip=totalliptinite;
MM
=mineral
matterother
than
pyrite;Pyr=pyrite;TPI=tissue
preservation
index;GI=gelification
index;GWI=groundwater
influence
index;
VI=vegetationindex.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–68 61
herbaceous/reed/and other monocotyledonen peats
give a high proportion of unstructured macerals
(humodetrinite) due to their lower lignin content is
not necessarily true. In addition, the general assump-
tion that gymnosperms are more resistant to decom-
position than woody angiosperms, which in turn are
more resistant than herbaceous angiosperm material,
may also be misleading (Dehmer, 1995). A wet forest
swamp may give rise to peats with a petrographic
composition similar to marsh peats if the depositional
conditions favour microbial destruction of the cellular
structure (Diessel, 1992). The best preserved tissues
are the deeper roots (Fig. 3f) that were protected from
aerial oxidation and reached below the peatigenic
layer.
In calcium-rich coals, neutral to alkaline deposi-
tional environments allow bacteria to cause severe
structural decomposition, leading to the formation of
humic gels and peatification products relatively rich in
nitrogen and hydrogen (Teichmuller et al., 1998a).
That is true for sample A173, which has the highest
humocollinite and nitrogen contents, although the
hydrogen content is rather low. The surrounding and
basement rocks of the Amynteo basin consist mainly
of crystalline limestones, which are supposed to be the
sources of calcium. A high content of eugelinite is
also characteristic of the calcium-rich brown coals
(see Fig. 3g). The presence of chlorophyllinite in the
upper lignite beds suggests wet and alkaline reducing
conditions (Cabrera et al., 1995; Dehmer, 1995;
Querol et al., 1996). A high content of calcium leads
to a high degree of bacterial degradation of the plant
remains and to bacterial reduction of sulphates, result-
ing in coals with high amounts of collinite and pyrite
(e.g. sample A173).
The pyrite content is relatively high (1.5–3.5
vol.%), in discordance with the presumed terrestrial
origin of the Apofysis lignites. Pyrite is found mostly
in the form of framboidal pyrite (Fig. 3h) and suggests
enhanced activity of sulphate-reducing bacteria, prob-
ably related to carbonate and sulphate-rich waters in
the basin during peat formation (Kuder et al., 1998;
Teichmuller et al., 1998a). Pyrite thus indicates a
marine influence and suggests that the Amynteo basin
was not totally isolated from the marine environment
during peat accumulation. Iron sulphide in peats can
be formed only through bacterial activity, since there
is insufficient energy for a purely chemical reduction
Fig. 3. Microphotographs of macerals in the Apofysis lignites: (a) phlobaphinite (ph) and suberinite (sub); (b) same field as (a) under blue light
irradiation; (c) humotelinite (ht) and humodetrinite (hd); (d) fusinite (fus), humodetrinite (hd) and humotelinite (ht); (e) humotelinite (htel),
humodetrinite (hdet) and corpohuminite (crph); (f) cross section of rootlet; (g) humotelinite (htel) and gelinite (gel); (h) framboidal pyrite. All
microphotographs were taken under reflected white light and oil immersion, except (b) and (f), which were taken under fluorescence-inducing
blue light.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–6862
Fig. 4. Microphotographs of macerals in the Apofysis lignites: (a) clay minerals and humodetrinite matrix; (b) porigelinite (por) intruded into
cell lumens; (c) Bogen structure of fusinite; (d) megaspore; (e) suberinite (sub) cell walls of a cortex; (f) compacted sporinite; (g) cutinite; (h)
megaspore. All photomicrographs were taken under fluorescence-inducing blue light and oil immersion, except (a), (b) and (c), which were
taken under reflected white light.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–68 63
Fig. 5. Ternary plots of (a) huminite, (inertinite + liptinite) and mineral matter contents and (b) of huminite, inertinite and liptinite contents (mmf).
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–6864
of sulphates to sulphides (Neavel, 1966). The iron
probably enters the swamp adsorbed on clays.
Because of this, pyrite is commonly found adjacent
to clay-rich zones (Cabrera et al., 1995). Though it is
difficult to recognize minerals in humodetrinite-rich
coals (Markic and Sachsenhofer, 1997), clays were
determined in this study as the main constituents of
the mineral matter (Fig. 4a and b).
Under aerobic degradation, the most resistant com-
ponents, like liptinite and mineral matter, are rela-
tively enriched, and increased amounts of the liptinite
group macerals may therefore indicate higher levels of
degradation in the peat swamp (Cabrera et al., 1995;
Rimmer et al., 2000). The high liptinite content of the
A139 sample corroborates the fact that the amount of
liptinite is generally high in coals with high mineral
matter content. The liptinite in this study consists
mostly of resinite and cutinite, macerals that are very
resistant to degradation and thus may preferentially be
preserved. The enrichment of liptinite macerals, such
as sporinite (Fig. 4d,f,h), cutinite (Fig. 4g) and resinite
as well as dispersed fragments of fusinite and semi-
fusinite in the form of inertodetrinite, in most of the
coal samples support the hypothesis that the peat was
subjected to severe humification (Ligouis et al., 1998).
Waxes are associated with a number of macerals,
especially cutinite and suberinite. A more temperate
climate with gymnosperm flora may also be inferred
from the presence of waxes and cutines, as also
suggested from palynological data from the nearby
Ptolemais basin (Singh and Singh, 2000; van Hoeve,
2000).
Ternary diagrams of specific maceral assemblages
are used for the evaluation of depositional conditions.
The depositional environment of the Apofysis lig-
nites, as shown in a ternary plot (Fig. 6), is not
definitely ascribed to forest swamp or a reed marsh
environment. These ternary plots are indicators only
and should be used complementary to palaeobotany
and palynology in order to determine the coal-forming
environments (DiMichele et al., 1987; Shearer and
Moore, 1994).
Diessel (1986) has introduced two petrographic
indices, i.e. the gelification index (GI) and tissue
preservation index (TPI). These indices were used to
characterize the depositional environments of Austral-
ian Permian coals. For low rank Miocene and Jurassic
coals, these indices have been modified by Kalkreuth
et al. (1991) and Petersen (1993), respectively. On the
basis of some criteria used in the classification of
modern peatlands, Calder et al. (1991) introduced the
groundwater influence index (GWI) and the vegeta-
tion index (VI) to characterize paleomires. In the
present study the formulas proposed by Georgako-
Fig. 6. Ternary plot showing suggested peat-forming environments for the Apofysis lignites, based on maceral assemblages (modified from
Kalkreuth et al., 1996).
inite
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–68 65
poulos and Valceva (2000) for TPI, VI and GWI and
by Petersen (1993) for GI have been adapted. The
formulae are:
TPI ¼ humoteliniteþ semifusiniteþ fusinite
humodetriniteþ humocollinite þ inertodetr
VI ¼ humoteliniteþ fusinite þ semifusinite þ scle
humodetriniteþ inertodetriniteþ liptodetriniteþ
GWI ¼ humodetriniteþ humocolliniteþ clay minerals
humotelinite
;
TPI is mainly governed by water depth and the
frequency of dry periods and is modified by pH and
trophic level, but the botanical composition plays also
GI ¼ huminite
inertinite
rotinite þ suberiniteþ resinite
sporiniteþ cutiniteþ fluorinite
a role. Low TPI values, for example, can be either the
result of the vegetation type (e.g. high angiosperm/
gymnosperm ratio) or due to less favourable condi-
tions of tissue preservation (Kolcon and Sachsenhofer,
1999). GI is a measure of groundwater table and/or
pH indicator, because gelification requires the contin-
uous presence of water and because microbial activity
requires low acidity (Kolcon and Sachsenhofer,
1999). A fluctuating water table caused by drier
periods may increase the wildfire frequency, which
also will influence the GI due to the formation of
inertinite during burning of the plants. These facies
indices should be treated with caution, since palae-
obotanical and/or palynological data are needed in
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–6866
order to have a more accurate description of the
palaeoenvironment (Calder, 1993; Collinson and
Scott, 1987; Crosdale, 1993).
The calculated values of TPI, GI, GWI and VI are
shown in Table 2. TPI values resemble VI values
except for sample A173, probably due to its high
humocollinite content. TPI versus GI and GWI versus
VI diagrams have also been used in order to determine
the depositional environments (Fig. 7). Low TPI and
high GI values are observed (Fig. 7a). TPI values less
than 0.5 and GI values higher than 6 suggest a
topogenous mire. The calculated values of GWI>1
and VI < 1 (Fig. 7b) suggest a rheotrophic site (limno-
telmatic or even inundated stage). GI>10 suggests a
marsh-reed environment or a forest with high degrees
of degradation, permanently flooded. These values
suggest either a limno-telmatic swamp with low sub-
sidence combined with a slow fall in the groundwater
table or a treeless, open marsh area with major
contributions from open marsh and limnic plant
communities. It is very difficult to separate telmatic
and limnic conditions, because subaquatic (limnic)
sedimentation also takes place in forest swamps and
particularly in reed swamps (Singh and Singh, 2000).
There is numerous evidence that support the first
hypothesis (i.e. limno-telmatic swamp). The high
pyrite content suggests enhanced bacterial activity,
which in turn destroys cellular structure and thus the
poor tissue preservation. The gastropods found in
lignites and intercalated marls from lower sections
reveal an alkaline environment and flooding events
(Inci, 1998; Markic and Sachsenhofer, 1997). An
Fig. 7. Plots of (a) gelification index (GI) versus tissue preservation index
index (VI) (modified from Diessel, 1986; Calder et al., 1991).
alkaline, calcerous non-marine environments is also
suggested by the abundance of humocollinite in the
lower lignite beds, as well as the high GI values
indicate a constant influx of calcium-rich waters into
the coal swamp (Markic and Sachsenhofer, 1997;
Singh and Singh, 2000). The negative correlation
between TPI and ash for the Apofysis lignites indicates
that intense clastic sedimentation reduced the tree
density and/or produced unfavourable conditions for
tissue preservation (Markic and Sachsenhofer, 1997).
In summary, it can be concluded that the Apof-
ysis deposit was autochthonous to hypoautochtho-
nous. The peat accumulation was governed by a
high groundwater level (wet telmatic to limno-tel-
matic facies) and a moderate subsidence rate. High
alkalinity, reducing conditions and marine influence
may be inferred from the presence of syngenetic
(framboidal) pyrite. The low TPI values indicate
high bacterial activity, and thus high pH conditions,
and the preservation of gastropod shells and chlor-
ophyllinite support an alkaline environment (Querol
et al., 1996).
5. Conclusions
The Apofysis lignites have an Eu-ulminite B reflec-
tance of 0.22% Rr and the investigated samples belong
to the lithotype category of matrix soft brown coals.
Huminite is the most abundant maceral group and
consists mostly of humodetrinite, whereas inertinite
has relatively low percentages and liptinite shows low
(TPI) and (b) groundwater influence index (GWI) versus vegetation
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–68 67
contents in the lower lignite beds and higher (up to
25.7 vol.%, mmf) in the upper lignite sections. Pyrite
content is relatively high (1.5–3.5 vol.%) in the
Apofysis lignites. Pyrite is found mostly in the form
of framboidal pyrite and suggests enhanced activity of
sulphate-reducing bacteria, probably related to carbo-
nate and sulphate-rich waters in the basin. The pres-
ence of high amounts of pyrites thus indicates a marine
influence on the precursor mires.
Low TPI and high GI values are observed. TPI less
than 0.5 and GI higher than 6 suggest a topogenous
mire. GWI>1 and VI < 1 suggest a rheotrophic site
(limno-telmatic or even inundated stage). GI>10
reveals a marsh-reed environment or a forest with
high degrees of degradation, permanently flooded.
The depositional environment of the Apofysis lignites
is not definitely ascribed to forest swamp or a reed
marsh environment. The high ash content of the
investigated samples is a clear indication of a top-
ogenous setting. High alkalinity and reducing condi-
tions may be inferred from the presence of syngenetic
(framboidal) pyrite, the low TPI values which indicate
high bacterial activity, and thus high pH conditions,
and the preservation of gastropod shells and chloro-
phyllinite. Thus, the Apofysis lignite deposit may be
interpreted as autochthonous to hypoautochthonous.
The peat accumulation was governed by a high
groundwater level (wet telmatic to limno-telmatic
facies) and a moderate subsidence rate.
All facies indices should be treated with caution,
since several authors have included or excluded
specific maceral types in their calculations, depending
on the rank and specific petrographic features of the
studied coals, which might result in misleading con-
clusions. Because of these ambiguities, petrographic
indices should be used together with independent
information, like palaeobotany and/or palynology in
order to give an integrated picture of the character-
istics of the depositional environment.
Acknowledgements
Financial support from Deutscher Akademischer
Austauschdienst (DAAD), through a short-term
research scholarship awarded to A. Iordanidis, is
gratefully acknowledged. The analytical work was
conducted at the Institute of Geology and Geo-
chemistry of Petroleum and Coal, RWTH-Aachen,
Germany. Professor Ralf Littke and scientific staff of
the former Institute are personally thanked. The help
of employees of the Public Power Corporation of
Greece during sampling is deeply appreciated. We are
also most thankful to W. Kalkreuth, T.A. Moore and
H.I. Petersen for their constructive review.
References
Antoniadis, P.A., 1992. Uber das Lignitvorkommen von Lava
(Kozani): Struktur, Bau und Palaogeographie nach Sedimento-
logischen Aspekten. Min. Metall. Ann., Athens 2, 87–106.
Antoniadis, P.A., Lampropoulou, E., 1995. Depositional environ-
ment interpretations based on coal facies analysis of Lava’s
lignite deposit (Greece). Doc. Nat. 96, 1–12.
Antoniadis, P.A., Rieber, E., 1997. Zu Fossilinhalt, Kohlegenese
und Stratigraphie des Kohlebeckens von Lava in Nord Grie-
chenland. Acta Palaeobot. 37 (1), 61–80.
Antoniadis, P.A., Blickwede, H., Kaouras, G., 1994. Polleninhalt
und petrographischer Aufbau des Flozabschnittes (36,0–51,0 m)
eine Tiefbohrung der obermiozanen Braunkohle von Lava bei
Kozani NW-Griechenland. Miner. Wealth, Athens 9, 7–17.
Cabrera, L., Hagemann, H.W., Pickel, W., Saez, A., 1995. The coal-
bearing, Cenozoic As Pontes Basin (northwestern Spain): geo-
logical influence on coal characteristics. Int. J. Coal Geol. 27,
201–226.
Calder, J.H., 1993. The evolution of a ground-water influenced
(Westphalian B) peat-forming ecosystem in a piedmont setting:
the No. 3 seam, Springhill coalfield, Cumberland Basin, Nova
Scotia. In: Cobb, J.C., Cecil, C.B. (Eds.), Modern and Ancient
Coal-Forming Environments. Geol. Soc. Am. Spec. Paper,
Boulder, CO, pp. 153–180.
Calder, J.H., Gibling, M.R., Mukhopadhyay, P.K., 1991. Peat for-
mation in a Westphalian B piedmont setting, Cumberland basin,
Nova Scotia: implications for the maceral-based interpretation
of rheotrophic and raised paleomires. Bull. Soc. Geol. Fr. 162,
283–298.
Cameron, A.R., Kalkreuth, W.D., Koukouzas, C.N., 1984. The pet-
rology of Greek brown coals. Int. J. Coal Geol. 4, 173–207.
Collinson, M.E., Scott, A.C., 1987. Implications of vegetational
change through the geological record on models of coal-forming
environments. In: Scott, A.C. (Ed.), Coal and Coal-Bearing
Strata: Recent Advances. Geol. Soc. Am. Spec. Paper, Boulder,
CO, pp. 67–85.
Crosdale, P.J., 1993. Coal maceral ratios as indicators of environ-
ment of deposition: do they work for ombrogenous mires? An
example from the Miocene of New Zealand. Org. Geochem. 20
(6), 797–809.
Dehmer, J., 1995. Petrological and organic geochemical investi-
gation of recent peats with known environments of deposition.
Int. J. Coal Geol. 28, 111–138.
Deutsches Institut fur Normung-DIN 51718, 1995. Testing of solid
fuels—determination of the water content and the moisture of
analysis sample.
A. Iordanidis, A. Georgakopoulos / International Journal of Coal Geology 54 (2003) 57–6868
Deutsches Institut fur Normung-DIN 51719, 1978. Testing of solid
fuels—determination of ash content.
Diessel, C.F.K., 1986. On the correlation between coal facies and
depositional environments. Advances in the Study of the Syd-
ney Basin, Proc. 20th Symposium, University of Newcastle,
Australia, pp. 19–22.
Diessel, C.F.K., 1992. Coal-Bearing Depositional Systems. Spring-
er-Verlag, Berlin. 721 pp.
DiMichele, W.A., Phillips, T.L., Olmstead, R.G., 1987. Opportun-
istic evolution: abiotic environmental stress and the fossil record
of plants. Rev. Palaeobot. Palynol. 151, 151–178.
Fowler, M.G., Gentzis, T., Goodarzi, F., Foscolos, A.E., 1991. The
petroleum potential of some Tertiary lignites from Northern
Greece as determined using pyrolysis and organic petrological
techniques. Org. Geochem. 17, 805–826.
Georgakopoulos, A., Valceva, S., 2000. Petrographic characteristics
of Neogene Lignites from the Ptolemais and Servia basins,
Northern Greece. Energy Sources 22, 587–602.
Hagemann, H.W., Wolf, M., 1987. New interpretations of the facies
of the Rhenish brown coal of West Germany. Int. J. Coal Geol.
7, 337–348.
Inci, U., 1998. Lignite and carbonate deposition in middle Lignite
succession of the Soma formation, Soma coalfield, Western
Turkey. Int. J. Coal Geol. 37, 287–313.
International Committee for Coal and Organic Petrology (ICCP),
1993. International Handbook of Coal Petrography, 2nd ed., 3rd
Suppl. University of Newcastle upon Tyne, England.
Kalaitzidis, S., Bouzinos, A., Christanis, K., 1998. The depositional
palaeoenvironment of the Upper Xylitic Horizon of the Ptole-
mais lignite deposit (in Greek). Proc. 8th Int. Congress Geol.
Soc. Greece (Patras, 27–29.5.1998). Bull. Geol. Soc. Greece,
vol. XXXII/2, pp. 289–297.
Kalaitzidis, S., Bouzinos, A., Christanis, K., 2000. The lignite-
forming palaeoenvironment before and after the volcanic tephra
deposition in the Ptolemais basin, Hellas (in Greek). Miner.
Wealth, Athens 115, 29–42.
Kalkreuth, W., Kotis, T., Papanicolaou, C., Kokkinakis, P., 1991.
The geology and coal petrology of a Miocene lignite profile at
Meliadi Mine, Katerini, Greece. Int. J. Coal Geol. 17, 51–67.
Kalkreuth, W., Riediger, C.L., McIntyre, D.J., Richardson, R.J.H.,
Fowler, M.G., Marchioni, D., 1996. Petrological, palynological
and geochemical characteristics of Eureka Sound Group coals
(Stenkul Fiord, southern Ellesmere Island, Arctic Canada).
Int. J. Coal Geol. 30, 151–182.
Kaouras, G., 1989. Kohlenpetrographische, palynologische und
sedimentologische Untersuchungen der Pliozanen Braunkohle
von Kariochori bei Ptolemais/NW Griechenland. PhD Thesis,
Georg-August-Universitat, Gottingen. 220 + 38 pp.
Kolcon, I., Sachsenhofer, R.F., 1999. Petrography, palynology and
depositional environments of the early Miocene Oberdorf lignite
seam (Styrian Basin, Austria). Int. J. Coal Geol. 4, 275–308.
Koukouzas, C., Kotis, T., Ploumidis, M., Metaxas, A., 1981. Coal
exploration of ‘Apofysis’ field of Anargiri –Amynteon area
(W. Macedonia). Research for energy sources, No. 1, Institute
of Geological and Mining Research. 52 pp. (in Greek with
English abstract).
Kuder, T., Kruge, M.A., Shearer, J.C., Miller, S.L., 1998. Environ-
mental and botanical controls on peatification—a comparative
study of two New Zealand restiad bogs using Py-GC/MS, pet-
rography and fungal analysis. Int. J. Coal Geol. 37, 3–27.
Ligouis, B., Lu, J., Pils, J., 1998. Coal petrology and Rock-Eval
pyrolysis of a coal seam in the Oligocene Molasse near Mies-
bach (Upper Bavaria, Germany): coal depositional environ-
ments. Bull. Soc. Geol. Fr. 169, 381–393.
Markic, M., Sachsenhofer, R.F., 1997. Petrographic composition
and depositional environments of the Pliocene Velenje lignite
seam (Slovenia). Int. J. Coal Geol. 33, 229–254.
Neavel, R.C., 1966. Sulfur in coal; its distribution in the seam and
in mine products. PhD Thesis, Penn State Univ. 332 pp.
Pavlides, S.B., Mountrakis, D.M., 1986. Neotectonics of the Flo-
rina–Vegoritis–Ptolemais Neogene Basin (NW Greece): an ex-
ample of extensional tectonics of the greater Aegean area. Ann.
Geol. Pays Hell. 33 (1), 311–327.
Petersen, H.I., 1993. Petrographic facies analysis of Lower and
Middle Jurassic coal seams on the island of Bornholm, Den-
mark. Int. J. Coal Geol. 22, 189–216.
Querol, X., Cabrera, Ll., Pickel, W., Lopez-Soler, A., Hagemann,
H.W., Fernandez-Turiel, J.L., 1996. Geological controls on the
quality of the Mequinenza subbituminous coal deposit, northeast
Spain. Int. J. Coal Geol. 29, 67–91.
Rimmer, S.M., Hower, J.C., Moore, T.A., Esterle, J.S., Walton, R.L.,
Helfrich, C.T., 2000. Petrography and palynology of the Blue
Gem coal bed (Middle Pennsylvanian), southeastern Kentucky,
USA. Int. J. Coal Geol. 42, 159–184.
Shearer, J.C., Moore, T.A., 1994. Botanical control on banding
character in two New Zealand coal beds. Palaeogeogr. Palaeocl.
Palaeoecol. 110 (1), 11–28.
Singh, M.P., Singh, A.K., 2000. Petrographic characteristics and
depositional conditions of Eocene coals of platform basins,
Meghalaya, India. Int. J. Coal Geol. 42, 315–356.
Teichmuller, M., Littke, R., Taylor, G.H., 1998a. The origin of
organic matter in sedimentary rocks. In: Taylor, G.H., Teichmul-
ler, M., Davis, A., Diessel, C.F.K., Littke, R., Robert, P. (Eds.),
Organic Petrology. Gebruder Borntraeger, Berlin. 704 pp.
Teichmuller, M., Taylor, G.H., Littke, R., 1998b. The nature of
organic matter-macerals and associated minerals. In: Taylor,
G.H., Teichmuller, M., Davis, A., Diessel, C.F.K., Littke, R.,
Robert, P. (Eds.), Organic Petrology. Gebruder Borntraeger,
Berlin. 704 pp.
Valceva, S., Georgakopoulos, A., Markova, K., 1995. The relation-
ship between petrographic composition and some chemical
properties for the Ptolemais Basin lignite, Greece. In: Pajares,
J.A., Tascon, J.M.D. (Eds.), Coal Science: Proc. 8th Int. Conf.
on Coal Science. Coal Science and Technology, vol. 24. Elsevier,
Amsterdam, pp. 259–262.
van Hoeve, M.L., 2000. Cyclic changes in the late Neogene vege-
tation of northern Greece. PhD Thesis, LPP Contributions Series
No. 12, Utrecht. 131 pp.