diatomaceous sedimentation in late neogene lacustrine basins of western macedonia, greece
TRANSCRIPT
ORIGINAL PAPER
Diatomaceous sedimentation in late Neogene lacustrinebasins of western Macedonia, Greece
R. B. Owen • R. W. Renaut • M. G Stamatakis
Received: 31 August 2009 / Accepted: 19 January 2010 / Published online: 4 February 2010
� Springer Science+Business Media B.V. 2010
Abstract Several lacustrine basins were formed by
late Miocene tectonic processes in western Macedo-
nia, Greece. These were occupied by a series of lakes
and wetland swamps during the late Miocene and
early Pliocene giving rise to diatomaceous clay-
stones, siltstones and diatom-bearing tufa deposits.
Diatoms are rare or fragmentary in sandstones and
chemical sediments, and are absent in conglomerates.
The Fe2?-rich phosphate minerals anapaite and
vivianite are present in parts of the diatomaceous
siltstones. Six major diatom groups were identified
using cluster and correspondence analyses, each of
which tends to be associated with a particular
lithofacies. The floras are indicative of mildly acidic
to alkaline water of varying depths. The dominant
taxa include Aulacoseira ambigua, A. distans,
Cyclotella iris and several of its varieties, C. aegeae,
C. castracanei, C. elymaea, C. ocellata, and two
unidentified Cyclotella. Fragilariaceae are common,
consisting mainly of Fragilaria bituminosa, Pseu-
dostaurosira brevistriata, P. zeilleri, Staurosira
construens, Staurosirella leptostauron, and S. pin-
nata. Locally, chysophycean stomatocysts are com-
mon, suggesting more oligotrophic conditions. Nine
diatom stages are recognized in the Lower Neogene
Series at Kariditsa (Kozani basin), reflecting shallow
swamps, small alkaline lakes, and terrestrial settings.
The Upper Neogene Series rocks are characterized by
Mg-rich carbonates such as hydromagnesite, huntite
and magnesite. A detailed stratigraphy was developed
for Mio-Pliocene deposits in the Florina basin at
Klidi. Parts of this sequence show clear cyclicity in
both the sediments and the diatom floras, with
shallow-water diatoms repeatedly giving way to taxa
indicative of deeper conditions. Larger-scale, shal-
low-deep cycles are also present and may be related
to precession- and eccentricity-forced climate
change.
Keywords Climatic change � Diatoms �Lacustrine basins � Greece
Introduction
This study involves investigation of late Miocene and
Pliocene diatomaceous deposits in western Macedo-
nia, Greece. Several researchers have previously
examined Neogene diatom floras in southeastern
R. B. Owen (&)
Department of Geography, Hong Kong Baptist
University, Kowloon Tong, Hong Kong
e-mail: [email protected]
R. W. Renaut
Department of Geological Sciences, University of
Saskatchewan, Saskatoon, SK S7N 5E2, Canada
e-mail: [email protected]
M. G Stamatakis
Department of Geology, University of Athens,
Panepistimiopolis, Ano Ilissia, 157 84 Athens, Greece
e-mail: [email protected]
123
J Paleolimnol (2010) 44:343–359
DOI 10.1007/s10933-010-9409-5
Europe and also in neighboring Turkey. Ognjanova-
Rumenova (2000) outlined the general biostratigra-
phy of diatoms in the Balkans, noting that the oldest
lacustrine floras date to the middle Miocene. There
also have been many site-specific studies, particularly
in Bulgaria (Temniskova-Topalova and Ognjanova-
Rumenova 1988; Ognjanova-Rumenova and Popova
1996; Temniskova et al. 1996; Temniskova-Topalova
et al. 1996; Ognjanova-Rumenova 2001, 2004;
Ognjanova-Rumenova et al. 2008). Ognjanova-
Rumenova (2005) presented the Neogene diatom
stratigraphy of a core from the Bitola basin in the
Former Yugoslav Republic of Macedonia (FYROM),
which lies to the north of the present study area.
Rehakova (1980) and Ognjanova-Rumenova and
Vass (1998) have documented the diatoms in Neo-
gene lacustrine deposits in Slovakia, with the latter
authors reporting dominance by several varieties of
Cyclotella iris Brun & Herib. and many Fragilaria
species. Servant-Vildary et al. (1986) and Gurel and
Yildiz (2007) have carried out similar investigations
of Miocene and Pliocene diatoms in Turkey.
Several investigations have focused on taxonomic
aspects of the fossil floras in the region. Examples of
such studies include the work of Ognjanova-
Rumenova et al. (1990) on Fragilaria and Ognjano-
va-Rumenova (2005) on C. iris and its varieties.
Ecomomou-Amilli (1987, 1999) and John and
Economou-Amilli (1990) have presented taxonomic
descriptions of Greek fossil diatoms. Diatom inves-
tigations of single samples from the study area
reported in this work (Ptolemeis and Kozani basins,
Fig. 1) include a taxonomic listing by Gersonde and
Velitzelos (1977) and a description of a new species,
Cyclotella elymaea Ec.-Amilli (1991.
This investigation is based on diatomaceous sed-
iments collected from quarries and natural outcrops
in the Greek Macedonian Florina-Ptolemais-Kozani
basin (Fig. 1a). This constitutes part of the 180-km-
long Pelagonia graben, which extends into the
FYROM and was formed after the Savanian orogeny
and early Miocene peneplanization of the Balkans
(Dumurdzanov et al. 1997). Various parts of the basin
contained lakes from the middle Miocene through to
the end of the Pliocene and perhaps into the
Pleistocene (Dumurdzanov et al. 2004). This study
focuses on the upper Miocene and Pliocene sediments
of the Florina and Kozani basins, with the major aims
of (1) determining the diatom floras; (2) establishing
a high-resolution diatom stratigraphy; and (3)
a bFig. 1 Location and
geology of the Florina-
Ptolemais-Kozani Basin.
a Geographic extent,
location and generalized
stratigraphic section after
Ehlers (1960) in Steenbrink
et al. (2006). b Detail of the
Kozani Basin showing
geology and sampling
locations
344 J Paleolimnol (2010) 44:343–359
123
combining lithofacies and diatom data in order to
reconstruct the paleolimnological conditions that
prevailed in the area during the late Miocene and
Pliocene.
Geological background
The Miocene basins of Greece are usually bounded
by major normal faults while minor faults affect basin
infills (Ioakim et al. 2005; Diamantopoulos 2006).
The location of the NNW–SSE chain of lake basins in
the study area (Florina, Ptolemais, Kozani) is shown
in Fig. 1a. Neogene sediments are widespread within
this tectonic graben, which developed in response to
late Miocene NE–SW extension in the westernmost
zone of the Internal Hellenides (Brunn 1956). Late
Pleistocene NW–SE extension fractured the area into
the Florina, Ptolemais and Servia (Kozani) Basins
(Pavlides and Mountrakis 1987), which extend over a
distance of about 120 km and lie between 300 and
700 m above sea level, adjacent to mountains that
rise to about 2,000 m. The basement includes meta-
morphic rocks, limestones, dolostones, flysch and
ophiolites (Dermitzakis and Papanicolaou 1981).
Steenbrink et al. (2006) have described several
quarry outcrops in the region, noting that about
600 m of lake sediments were laid down during the
Upper Miocene through Lower Pliocene. These
consisted of intercalated lignites, alluvial sands and
conglomerates that occur in four lithostratigraphic
units (Fig. 1a). Shallow lacustrine diatomaceous
deposits and lignites formed the dominant compo-
nents of the Komnina and Ptolomais Formations and
were related to precession-induced climate cycles.
The general environmental setting of the lignites have
been noted by Christanis (2004) with Oikonomopo-
ulos et al. (2008) providing detailed characteristics of
the lignites at Achlada (Florina Basin), close to Klidi
(Fig. 1a). Stamatakis (2004) and Koukouzas et al.
(2009) have documented the detailed mineralogy and
geochemistry of parts of the lacustrine clayey diat-
omites at Vegora and Komnina (Ptolemais Basin),
with Koukouzas (2007) providing descriptions of the
mineralogy of lignites at Achlada (Florina Basin).
Two distinct stratigraphic units have been recog-
nized in the Kozani Basin: a) the Lower Neogene
Series (LNS), and b) the Upper Neogene Series (UNS)
(Fig. 1b) (Anastopoulos and Koucouzas 1969). The
LNS consists of up to 400 m of marlstones with rare
lignite and chert intercalations (Stamatakis et al.
1989). The UNS includes Mg-rich carbonates, marl-
stones, marly diatomites, claystones and poorly com-
pacted ash-tuffs (Stamatakis et al. 1989; Stamatakis
1994, 1995; Calvo et al. 1995; Hall and Stamatakis
2000). Based on botanical evidence, Velitzelos and
Knobloch (1986) reported the age of the UNS in the
southern part of the basin as Late Miocene.
Methods
Samples were collected from seven outcrops of
varying thickness (1–37.3 m) in the Kozani and
Florina Basins (Fig. 1). Two of the longer sections at
Kariditsa (Kozani) and Klidi (Florina) were examined
in greater detail with samples for diatom analyses
collected at 10–15-cm intervals and at lithological
boundaries. Carbonates were removed from the
sediments by adding 10%HCl to about 1 cm3 of
sample, followed by washing in distilled water. This
process assisted with disaggregation of the material.
Aliquots of suspended diatoms and sediment were
then dried on cover slips, prior to mounting on smear
slides with Naphrax. The diatoms were examined
using an Olympus microscope with phase contrast
and brightfield illumination at 1,0009 magnification.
Several diatom identifications, particularly for Cy-
clotella, were confirmed using a LEO 1530 Field
Emission Scanning Electron Microscope.
The various species were mainly identified using
the works of Heribaud (1893), Ehrlich (1966), Gasse
(1980), Serieyssol (1980, 1984), Krammer and Lange
Bertalot (1986, 1988, 1991a, b), Loginova et al.
(1990), Ognjanova-Rumenova et al. (1990), Round
et al. (1990) and Ognjanova-Rumenova (1996). A
minimum of 400 diatoms was counted along transects
on each slide, except where diatoms were rare and all
diatoms were tallied. Diatoms were included in the
counts if there was at least half of the specimen
intact, which may have resulted in some underesti-
mation of the more fragile species. Apices were
counted and divided by two in the case of long thin
taxa such as Synedra in order to minimize errors due
to their fragility. Visual estimates were made of the
percentage of the carbonate-free sample that con-
sisted of diatoms (total intact ? fragmentary).
Diatom assemblages and sampling sites were dis-
tinguished using XLSTAT (Addinsoft) to carry out
J Paleolimnol (2010) 44:343–359 345
123
Agglomerative Hierarchical Cluster Analyses (AHC).
Pearson Dissimilarity and Unweighted Pair-group
Mean Averaging (UPGMA), using all diatom taxa,
were adopted after exploring several AHC techniques.
Dendrograms were generated for both samples and
species (Fig. 5b, d). Only taxa that comprised C5% of
the flora in at least two samples, or C10% in at least one
sample (43 taxa), are shown in the species dendrogram.
CANOCO 4.51 was used to carry out correspondence
analyses for diatoms (Fig. 5a, c) with only diatoms that
formed C5% of the flora in at least one sample (60)
being shown in Fig 5a.
The plotting program C2 was used to construct
stratigraphic diagrams. Environmental reconstructions
for pH were based on training sets and transfer
functions provided by the European Diatom Database
(EDDI, http://craticula.ncl.ac.uk/Eddi/jsp/index.jsp).
This study made use of the combined pH training set
and Locally-weighted Weighted Averaging (LWWA),
which generates a local training set for each fossil
sample based on the 50 closest analogues defined by
the minimum chi-squared distance. Extinct taxa
ranged between about 0–9% of the species present
and were excluded prior to analysis, reducing the
reliability of the results accordingly. Water depths
were assessed qualitatively using known habitat
preferences (Gasse 1986; Ognjanova-Rumenova and
Popova 1996).
Results
Lithofacies
The sediments were examined in five logged sections
(Fig. 2) in the Florina and Kozani Basins and in
several small supplementary outcrops. The main
lithologies include organic-rich lignitic horizons and
clayey siltstones, a variety of diatomaceous and non-
diatomaceous siltstones, sandstones, conglomerates,
diatomites, tufas, marlstones and limestones, as well
as deposits of huntite and magnesite.
One long section was examined in the Florina
Basin at a lignite quarry near Klidi village (Fig. 1a).
Clastic and biogenic materials dominate (Fig. 3a)
with lignites occurring at the bottom of section FK1
(Fig. 2a) and extending for several tens of meters
below the sampled sequence (Fig. 3b). Within the
sampled section (Units 1–5, FK1a, Fig 2a), these
organic deposits consist of alternating black lignite
and yellowish non-diatomaceous siltstones (Fig. 3c).
Fresh horizontally oriented, brown, wood stems and
branches occur locally and there is a lack of evidence
for in situ growth. Individual lignitic beds are
laterally extensive but vary in thickness, having a
wavy form. Many of the coals are rich in gymno-
sperms (Papanicolaou et al. 2000).
White diatomaceous siltstones constitute Units 6–9,
with varying clay content and the deposits being fissile
in Units 7–9. Unit 10 contains organic-rich fissile
siltstones, with common ostracods. Large fragments of
wood lie parallel to the bedding with organics being
more abundant at the base of the sequence, which
laterally grades into lignite.
Units 11–18 are dominated by white to grey
diatomaceous siltstones that show a distinct cyclicity
that has been used to define the seven units in this
part of the succession. They typically consist of a
thick (20–90 cm), massive, white (when dry), diato-
maceous siltstone that passes upwards into a thin
(2–10 cm) grey clayey siltstone (Fig. 3d) along
which the different units tend to break. Rare pebbles
(\3 cm) occur in Unit 14. Whole and fragmented
leaves of angiosperms and various aquatic macro-
phytes are scattered throughout these sediments
(Fig. 3g–j) and are especially abundant in Units 14
and 18 where they are associated with the develop-
ment of vivianite (Fe3(PO4)2�8(H2O)) (Fig. 3f).
Units 19–28 consist of generally thicker (about
70–600 cm) sequences of massive white diatoma-
ceous siltstone. Leaves are less common in Units 19–
21, with minor vivianite in Unit 19. The succeeding
Units 24–28 contain abundant leaf fossils with one
flower fragment (Fig. 3k) in the base of Unit 26. A
distinct layer rich in anapaite (Ca2Fe (PO4)2�4(H2O))
nodules (\1-cm diameter) forms Unit 29 (Plate 1e).
The nodules (faecal pellets?) extend into the base of
Unit 30, which is a massive, 260-cm-thick, grey
diatomaceous siltstone. Anapaite nodules also occur
in Unit 31, which consists of alternating wispy white
diatomite and grey clayey diatomaceous siltstone.
Grey siltstones dominate in Units 32–36, except for
Unit 33, which is lighter in color and Unit 35, which
is comprised of alternating clayey diatomaceous
siltstones and diatomites.
The sediments in the Kozani Basin were sampled
at several locations and consist of a variety of clastic,
346 J Paleolimnol (2010) 44:343–359
123
biogenic and chemical sediments (Fig. 4). The rock
types of the Lower Neogene Series at Kariditsa
(Figs. 1b, 2b, 4a) are comprised mainly of fine-grained
lithologies (claystones, siltstones, sandy siltstones)
with many horizons containing gastropods. A promi-
nent lignite constitutes Unit 11 in Section KK1
(Fig. 2b). The deposits of the Upper Neogene Series
(KP1, KM1 and KM2, Figs. 2b, 4b–f) are more varied.
They include siliciclastic claystones, siltstones, sand-
stones and conglomerates, with ripple cross-laminae
and cross beds in several sandstones. Locally, sand-
filled channels are present. Gastropods occur in both
siliciclastic and biogenic (diatomaceous siltstone,
diatomite, tufa, limestone) facies. Chemical sediments
are dominated by huntite (Mg3Ca(CO3)4), magnesite
(MgCO3) and hydromagnesite Mg5(CO3)4(OH)2�4(H2O)
that were deposited in small shallow late Neogene
alkaline lakes (Wetzenstein 1975; Stamatakis 1995).
The diatom floras
A total of 133 taxa was recognized in the sections
from the Florina and Kozani Basins. Extinct species
accounted for 12% of the total flora, but locally
accounted for 0–31% of the diatoms in the assem-
blages. Preservation ranged from poor to excellent
with corrosion being more prevalent in association
with the Upper Neogene chemical sediments of the
Kozani Basin. Figure 5b shows a cluster analysis of
the most common species observed in all of the
sampling sites. Six major groups can be distinguished
at the 0.42 level of dissimilarity, which corresponds
with a major step in the clustering.
Group 1 is comprised of Aulacoseira ambigua
(Grun.) Simons., which forms near-monospecific
floras (up to 99.5%) in diatomites or highly diato-
maceous deposits (Units 30–33 of FK1, Fig. 2)
* **
*
*
1.5 m gap
2 m gap
2m gap
Section FK1
4
12
1
35
6
7
89 10
11131415161718192021
2
Lower Neogene
UpperNeogene
KP1
KK1
KM2KM1
nisabinazoKbnisabanirolFa
3 m
etre
s
White siltstoneLight grey siltstone
Clayey siltstone
Yellowish siltstone
Conglomerate
Sandy siltstone
Massive sandstone
Thin bedsFissile white siltstoneCherty limestoneClaystoneCross-bedded ss.
Limestone
Huntite/
MagnesiteHuntiteSiliciclastic
Brown siltstone
Lignite and wood1
2 3 4
5 6
7
8 9 10
11 12 13
14
15
16
17
18
19
21
20
23
22
24
25
26
27
28
29
30
31
32
33
34
35
36
37
1 2 3 4 5 6 7 8 9
10
11
12
13 14 15 16 17
18
19
20
1
2
3
1
2
3
4
5
6
7
8
9 10
11
12
13 14 15 16 17 18
Diatom samples
Stratigraphicunit
FK1a
FK1b
FK1c
FK1d
Pyrite noduleLeavesFlower
*
*
* VivianiteAnapaite
OstracodsGastropods
hydromagnesite/magnesite
Peb
bles
Fig. 2 Lithological logs.
a Klidi Quarry section,
Florina Basin. b Kozani
Basin sections. Locations
are shown in Fig. 1
J Paleolimnol (2010) 44:343–359 347
123
towards the top of the Klidi Quarry section (Florina
Basin). Occasional Staurosira construens Ehr. are
also present, but in low numbers.
Group 2 floras occur in diatomaceous siltstones in
several locations in both the Kozani and Florina
Basins. The group is characterized by a greater
Fig. 3 Sediments at the Klidi Quarry, Florina Basin. a General
view with white to grey diatomaceous siltstones overlying
darker lignites; b Alternating lignites and siltstones, white
bar = 1 m; c Detail of the basal part of the Klidi section
showing the transition from lignites to diatomaceous sediments
(Unit 6 upwards), tape = 1 m; d Cyclic diatomaceous sedi-
ments with thin and darker clayey siltstones at the top of each
unit, tape = 1 m; e Anapaite nodules (black arrow) in clayey
diatomaceous siltstone; f Vivianite alteration (black arrows) of
leaf debris; g–j Well-preserved leaf fossils; k Flower present in
Unit 26; l Conglomerates from the top of the succession, which
rest unconformably on the diatomaceous deposits
348 J Paleolimnol (2010) 44:343–359
123
variety of species than Group 1 and could perhaps be
further subdivided (Fig. 5b) with S. construens and
Pseudostaurosira brevistriata (Grun. in V. Heurck.)
Will. & Round forming one sub-group (2A, Fig. 5b).
Subgroup 2B is comprised of Actinocyclus makaro-
vae Temn. & Ognjan., Ellerbeckia kochii (Pant.)
Temn., Val. & Ognjan., Cyclotella castracanei Eul.,
C. iris, Cyclotella iris var. ovalis Brun & Herib.,
Fragilaria bituminosa Pant., Pseudostaurosira brev-
istriata (Grun. in V. Heurck) Will. & Round and
Pseudostaurosira zeilleri (Herib.) Will. & Round.
The third major grouping includes two unidenti-
fied Cyclotella species, plus Cyclotella iris var.
cocconeiformis Brun & Herib., Cyclotella iris var.
integra Perag. & Herib.. Aulacoseira distans (Kutz.)
Simons. also falls within this group, but with a
relatively higher level of dissimilarity separating it
from the Cyclotella taxa (Fig. 5b). This flora was
confined to diatomaceous siltstones in the Klidi
Quarry. Group 4 is also dominated by Cyclotella
species, which are dominated by C. elymaea and
Cyclotella ocellata Pant. Group 4 occurred in highly
diatomaceous siltstones in the upper part (above Unit
27 in FK1, Fig. 2) of the Klidi Quarry section in the
Florina Basin.
Group 5 is comprised of Anomoeoneis sphaero-
phora (Kutz.) Pfitz., which generally constitutes close
to 100% of the flora, but with the occasional presence
of an unidentified Navicula designated ‘‘sp. 5’’. This
grouping was present in the upper parts of the lower
Neogene Kariditsa section (KK1), where it was found
in claystones.
Group 6 is the most diverse of the clusters that
were recognized and is comprised of a variety of
Fig. 4 Sediments from the Kozani Basin. Black vertical bars
are approximately 2 m. a: Kariditsa. Diatomaceous and non-
diatomaceous siltstones and claystones with a dark lignite layer
towards the base; b: Huntite/hydromagnesite quarry section
(KM2; Fig. 2) near Neraida, diatoms absent from the sequence;
c: Magnesite Quarry section (KM1; Fig. 2) near Neraida,
diatoms rare in the white basal magnesite and abundant in the
overlying siltstones and a carbonate that lies between these two
major units; d: Tufa mound at the huntite/hydromagnesite
quarries near Neraida village, diatoms rare; e: Section KR1
near Neraida. Diatoms are absent except in the upper 4 m. f:
Section KP1 at Stena Portas (old magnesite quarry). White
magnesite-rich beds at the base gives way to about 2 m of
sediment with rare to moderately abundant diatoms. Diatoms
absent in the upper sediments
J Paleolimnol (2010) 44:343–359 349
123
benthic and epiphytic diatoms that are largely con-
fined to the Kozani Basin. The flora can perhaps be
further subdivided at a low dissimilarity level of 0.08
(Fig. 5). Subgroup 6a (Cymbella helvetica Kutz.,
Epithemia sorex Kutz., Staurosirella leptostauron
(Ehr.) Will. & Round) occurred in siltstones at
Kariditsa (KK1, Fig. 2). Subgroup 6b (Cyclotella
aegeae Ec,-Amilli, Navicula bituminosa Pant.) was
confined to the base of the Stena Portas sequence
(Units 2–10 in KP1, Fig. 2), where it formed a sparse
flora in siltstones associated with reworked huntite.
Diatoms belonging to Subgroup 6c (Cymbella, Gom-
phonema and Eunotia floras, plus Nitzschia sinuata
var. tabellaria Grun.) occur mainly at Kariditsa
(KK1, Figs. 1 and 2) in siltstones, often with
gastropods. Group 6d includes a diverse range of
diatoms (e.g., Synedra ulna (Nitz.) Ehr., Fragilaria
hungarica Pant., Nitzschia frustulum (Kutz.) Grun.;
a b
c
d
Fig. 5 Multivariate
Analyses of the diatom
data. a Correspondence
Analysis for diatom species;
b Cluster analysis for
diatom species; cCorrespondence Analysis
for samples from the Klidi
and Kozani areas; d Cluster
Analysis for samples
350 J Paleolimnol (2010) 44:343–359
123
Fig. 5b), which also occurred present in siltstones at
Kariditsa.
Cluster analyses show a clear separation of the
samples from the Florina and Kozani Basins, with the
exception of a small number of outliers. For example,
sample R06 from the Kozani area appears to be related
to samples from the middle and lower parts of the Klidi
section in the Florina Basin. The general spatial
separation of samples is clearly visible in correspon-
dence analyses (CA) (Fig. 5c) with Kozani samples
plotting in Quadrant IV and part of Quadrant II. The CA
for the Klidi Quarry material also shows a distinct trend,
with samples from the basal part of the sequence lying in
Quadrant III and those from the top of the deposits
occurring in Quadrant II. Figure 5a presents a CA for
species, with diatoms belonging to the six major groups
identified from cluster analysis shaded. These data
reinforce the separation of these various groupings.
Diatom stratigraphy
Detailed diatom stratigraphies were generated for two
of the longest sections. Figure 6 shows the results for
Section FK1 from the Klidi Quarry. The sediments are
mainly dominated by Cyclotella, A. ambigua and
several species of Fragilariaceae, with S. construens,
P. brevistriata and Staurosirella pinnata (Ehr.) Will. &
Round occurring to varying degrees throughout the
diatomaceous parts of the sequence. Ten major stages
(A–J) can be recognized based on the diatom floras and
diatom abundance in the sediments. Only rare and
fragmentary diatoms occur in Stage A deposits, which
consist of alternating lignites and pale yellowish
siltstones. Epithemia and Cymbella taxa characterize
Stage B, together with A. ambigua and Cocconeis
placentula Ehr.. Cyclotella sp. 1 is similar to a
cyclotelloid taxon, with the same designation,
described by Ognjanova-Rumenova (2005) from the
Bitola Basin. She notes its resemblance to C. ocellata,
but with differences in terms of marginal and central
fultoportulae, the presence of spines and a variable
elliptical to circular shape. Other common taxa include
Fragilaria bituminosa Pant, P. brevistriata, S. constru-
ens and S. pinnata.
Stage C deposits are comprised of diatomaceous
siltstones and diatomites and are characterized by the
presence of C. elymaea and relatively abundant
C. iris var. ovalis. Other common taxa include
Cyclotella sp. 1, F. bituminosa, P. brevistriata,
S. construens and S. pinnata. Cymbella and Epith-
emia taxa disappear at the base of this stage, which
can perhaps be subdivided further based on the higher
percentages of S. construens and S. pinnata in
Substage Ci (Fig. 6).
Cyclotella elymaea disappears in the diatomites
that comprise Stage D, which can be subdivided
using C. iris var. ovalis. This taxon is less common
than S. construens in Substage Di, but more abundant
in Substage Dii. Cyclotella elymaea is again present
in Stage E sediments, with C. iris becoming a
common diatom and C. iris var. ovalis remaining a
major part of the flora.
Cyclotella castracanei and C. ocellata form impor-
tant elements in the flora for the first time from the basal
diatomites of Stage F. Cyclotella elymaea remains
common while C. iris declines and C. iris var. ovalis
remains an important element of the flora. Cyclotella
sp. 1 occurs only at trace levels of \1% in the
diatomaceous silts of Stage G, and C. ocellata becomes
dominant. Cyclotella castracanei remains common.
Diatomaceous silts and diatomites constitute Stage
H, which is distinguished by the abundance of
A. ambigua. At several horizons this species forms
nearly monospecific floras in diatomite. Cyclotella
elymaea disappears from the flora as do Actinocyclus
makarovae and E. kochii, which form a small (\5%)
component of the floras throughout Stages D–G and
parts of Stage B and C. Diatoms are absent or occur
as rare fragments in the siltstones and claystones of
Stage I, but reappear in Stage J where C. castracanei
is co-dominant with C. ocellata.
The second diatom stratigraphy (KK1, Fig. 7) was
developed for outcrops at Kariditsa and represents the
lower Neogene of the Kozani Basin. Nine stages can be
identified. Stage A occurs in white siltstones domi-
nated by Navicula bituminosa. The overlying, gastro-
pod-rich, white siltstones contain a sparse (Stage B)
flora dominated by Navicula sp. 4, Neidium affine
(Ehr.) Pfitz. and Neidium iridis (Ehr.) Cl.. Diatoms are
more common in the Stage C siltstones, which also
contain common gastropods and a diatom flora dom-
inated by N. bituminosa with less common Synedra
ulna (Nitz.) Ehr., and several taxa belonging to
Gomphonema, Eunotia and Cymbella (Fig. 7). Stage
D is confined to a relatively thin clayey siltstone and is
dominated by S. leptostauron.
Diatoms are absent in the fissile, gastropod-rich,
white siltstones, cherty limestone, claystone and
J Paleolimnol (2010) 44:343–359 351
123
lignite that make up Stage E. The succeeding Stage F
is dominated by A. ambigua in siltstones with a few
leaf fossils. S. ulna and Eunotia spp. are common as
is Navicula sp. 5. Stage G occurs in similar
sediments, but is dominated by S. ulna, A. sphaero-
phora and several Gomphonema and Cymbella taxa
plus Nitzschia sinuata var. tabulata. Diatoms are
again absent in Stage H, which occurs in siltstones
and claystones with gastropods. The top of the
sequence comprises Stage I where diatoms are sparse
and comprised solely of A. sphaerophora.
The diatoms in the Upper Neogene Series of
Kozani were detected in a small outcrop, close to the
old Aliakmon Bridge (KS1; Fig. 1) and in parts of
several longer sections (KR1, KM1, KM2, KP1;
Figs. 1 and 2). A sparse diatom flora occurred in the
lower parts of the sediments at Stena Portas (Fig. 1).
There, Units 1 and 2 consist of huntite and magnesite
and lacked diatoms (KP1, Fig 2). Units 2–6 and 8
and 9 contained a sparse flora dominated by
C. aegeae, C. elymaea and N. frustulum, together
with A. sphaerophora and Thalassiosira sp. 1. Unit 7
contains moderately common diatoms and is domi-
nated by Cyclotella sp. 3. Units 10 and 11 are domi-
nated by moderately common C. aegeae (81–85%) and
Cyclotella sp. 3. Diatoms are rare and fragmentary in
the remaining Units 12–20.
The huntite/hydromagnesite quarries of Neraida
that belong to the Upper Neogene Series were exam-
ined at sections KM1 and KM2 (Figs. 1 and 2).
Diatoms were absent or scarce in KM2, but were
present in all units of KM1. In the latter section, Unit 1
is comprised of huntite/hydromagnesite with diatoms
forming\5% of the deposit. The most common taxa
40 0
400
800
1200
1600
2000
2400
2800
3200
3600
100%
Abu
ndan
ce
50%
Cyc
lote
lla c
astr
acan
eiC
. dis
tingu
ida
C. e
lym
aea
C. i
risC
. iris
v. c
occo
neifo
rmis
C. i
ris v
. int
egra
C. i
ris v
. ova
lisC
. oce
llata
Cyc
lote
lla s
p. 1
Cyc
lote
lla s
p. 2
Act
inoc
yclu
s m
akar
ovae
Elle
rbec
kia
koch
iiA
ulac
osei
ra a
mbi
gua
A. d
ista
nsA
. gra
nula
taF
ragi
laria
bitu
min
osa
Pse
udos
taur
osira
bre
vist
riata
Sta
uros
ira c
onst
ruen
s
Fra
gila
ria h
unga
rica
Sta
uros
irella
lept
osta
uron
Sta
uros
irella
pin
nata
Pse
udos
taur
osira
zei
lleri
Coc
cone
ois
plac
entu
la
Nav
icul
a sp
p.A
chna
nthe
s sp
p.C
ymbe
lla s
pp.
Epi
them
ia s
pp.
Chy
soph
ycea
n cy
sts
Planktonic Facultative planktonic Benthonic Epiphytic
7 8 950pH
Habitat pH
Habitats:
Stage
A B Ci
Cii
Di
E
F
G
H
Diatoms rare, broken or absent Diatoms rare, broken or absent
tnesba ro nekorb ,erar smotaiDtnesba ro nekorb ,erar smotaiD
FK1
IJ
Dii
20
22
26
27
28
30
19
14
18 17
21
32 34
36
23
6
0 20 % diatomsand cycts % %
cm
Fig. 6 Diatom and chrysophycean stomatocyst stratigraphy for FK1, Florina Basin. Habitat and pH data are shown to the right.
Location is shown in Fig. 1
352 J Paleolimnol (2010) 44:343–359
123
included E. sorex (16%), S. pinnata (14%), Cymbella
cistula (Ehr.. in Hempr. & Ehr.) Kirchner (10%),
P. brevistriata (8%) and N. affine (6%). Unit 2 is a
carbonate dominated by E. sorex (22%), Navicula sp. 7
(20%) and C. helvetica (9%), N. frustulum (8%) and
C. ehrenbergii Kutz. (7%). Unit 3 consists of diato-
maceous brown siltstones with abundant and varied
diatom floras that include: C. ocellata (4–48%),
C. helvetica (20–42%), P. brevistriata (1–16%),
E. sorex (6–9%), S. pinnata (1–8%) and Gomphonema
parvulum (Kutz.) Kutz. (0–6%). Spring tufa mounds
within the huntite/hydromagnesite quarry floor yielded
no diatoms although a nearby stromatolitic carbonate
contained occasional S. leptostauron (20%), C. helve-
tica (20%) C. cistula (8%), A. granulata (8%) and
Mastogloia elliptica (Ag.) Cl. (5%).
Discussion
Environmental conditions in the Klidi area
Previous studies (Ehlers 1960; Stamatakis 1994,
1995; Steenbrink et al. 2006) have established the
existence of Late Miocene to late Early Pliocene
sedimentation in the Florina-Ptolomeis-Kozani chain
of basins. Several tens of metres of alternating
lignites and siltstones underlie the stratigraphic
section reported in this study. However, Oikono-
moupolos et al. (2008) have carried out detailed
investigations of these basal lignites at Achlada,
about 10 km north of Klidi. There, the organic
deposits have been reported as forming in peat
swamps on a floodplain crossed by a major mean-
dering river system, with at least some of the lignite
forming in an oxbow lake setting (Fig. 8a).
Alternating lignite seams and siltstones occur at
the base of FK1 (Fig. 2) and form the top of the
succession. Transported organics (wood fragments)
are present in the siltstones, but there is a lack of
rooted plants suggesting an origin by reworking of
swamp materials as a transgressing lake was inun-
dating them. Diatoms became well established with
the laying down of Unit 6 (Fig. 2) and the develop-
ment of Stage B floras (Fig. 6). These contain a
mixture of planktonic and facultative planktonic
diatoms and have the highest proportion of epiphytes
in the sequence. Transfer-function data (Fig. 6)
pH
Habitat pH
50%
Abun
danc
e
50%
Aulaco
seira
ambigu
a
Frag
ilaria
bitu
minos
a
Stau
rosira con
struen
s
Stau
rosirella
leptos
tauron
S. pinna
ta
Syne
dra ulna
Achn
anthidium m
inutissim
um
Coc
cone
is place
ntula
Anom
oeon
eis sp
haerop
hora
Nav
icula am
phice
phala
N. b
ituminos
a
Nav
icula sp
. 4
Nav
icula sp
. 5
Neidium
affine
N. Irid
is
Gom
phon
ema ac
uminatum
G. intric
atum
G. p
arvu
lum
Gom
phon
ema sp
. 2
Epith
emia sorex
Euno
tia pec
tinalis
E. lu
naris
E. prearup
ta
Amph
ora lib
yca
Cym
bella
asp
era
C. c
istula
C. turgida
Nitz
schia sinu
ata v. ta
bulata
6 8 100 50% 50%
Stage
AB
C
E
FG
H
I
D
KK1
0
50
100
150
200
250
300
350
400
450
500
550 cm
4
12
1
356
7
89 10111314151617181920
21
2
Stra
tigra
phic
units
Planktonic Facultative planktonic Benthonic Epiphytic Habitats:
Diatoms rare, broken or absent
Diatoms rare, broken or absent
Fig. 7 Diatoms stratigraphy for Section KK1, near Kariditsa, Kozani Basins. Location is shown in Fig. 1
J Paleolimnol (2010) 44:343–359 353
123
suggest freshwater conditions with pH values of
about 7.2–8.0.
Stage C is characterized by an overall increase in
planktonic diatoms. In Stage Ci, epiphytes decline
from their Stage B percentages and planktonic
species form their lowest contribution to the flora in
the entire section, suggesting very shallow open
water conditions. Transfer-function data indicate a
pH of up to 8.2. Subsequently (Stage Cii), there was
an increase in planktonic C. iris var. ovalis—an
oligotrophic diatom favoured by carbonate-rich water
and a pH of about 7.4 (Serieyssol 1984). Within each
of the depositional units (Units 11–18, FK1, Fig. 2)
of Stage Cii there is a gradual increase in planktonic
diatoms (e.g. C. iris var. ovalis) upwards followed by
a return to floras that suggest shallow water. The
sediments also document a distinct cyclicity with
each unit comprising a highly diatomaceous
sequence, at decimeter to metre thicknesses, passing
upwards into a thin (2–5-cm) clayey siltstone topped
by a sharp bedding plane. Cyclic sedimentation has
been previously reported from several other Florina-
Ptolemais-Kozani Basin (van Vugt et al. 1998;
Steenbrink et al. 1999, 2006) where cycles at
differing scales have been related to precession and
eccentricity orbital periods.
Stage C is also distinguished by a decrease in
diatom abundance from about 95% down to about
10% of the sediment (Units 16–17; Fig. 6), perhaps
related to increased river inputs and dilution of the
diatoms by clastic materials. This decline in diatom
abundance is also associated with the occurrence of
an increase in leaf fossils (Fig. 2), which are locally
abundant and associated with the development of
vivianite. Stamatakis (2004) notes similar leaf-vivia-
nite associations in clayey diatomites from other parts
of the Florina-Ptolemais-Kozani Basin and attributed
their origins to phosphorous enrichment caused by
high biological productivity in the catchment, with
additional phosphorous supplied by the decay of
leaves. Organic decay, or iron-reducing bacteria,
would have assisted in the reduction of iron to the
ferrous form, perhaps under a stratified water body
with anoxic bottom waters, or within deeper anoxic
muds. This would also be consistent with the
generally excellent preservation of leaves. The ideal
pH conditions for vivianite formation range from 6.4
to 7.8 (Nriagu and Dell 1974), values that are
Xi
Xiii
Xii
XivYi
Yiii
Yii
Yiv
X
Y
Meandering river Oxbow lakes
peat
peat
peat
Peat coverted to lignite after burial and time
Shallow swampy lake
Moderately deep lake
Lignite andsiltstone
Diatomaceoussiltstone
Shallowphase
Deepphase
a c
b Pleistocene fluvial pebbles Lake cycles
Miocene lignites
Saline pondsLake
Tufa moundsFloodplain withToxidaceae andmixed forest
(i)
(ii)
Fig. 8 Depositional
models for the Klidi Quarry
area, a–b Florina Basin.
‘‘a’’ represents basal
Miocene lignite
paleoenvironment; ‘‘b’’
shows lake cyclicity for the
main diatomaceous
siltstones and diatomites.
Low lake stages (i)
repeatedly expanded (ii)
and then contracted again.
These variations occurred at
two different time scales
involving multiple shorter
cycles (Xi–iv, Yi–iv) nested
within longer-term changes
(X, Y). c Sedimentation
model for the upper
Neogene of the Kozani
Basin. Tufa-forming springs
and local streams fed saline
ponds in which magnesium-
rich carbonates were laid
down. During low lake level
stages these deposits were
reworked into adjacent
deltaic settings (after Calvo
et al. 1995)
354 J Paleolimnol (2010) 44:343–359
123
consistent with the diatom data that show lacustrine
pH values falling to about 7.5 in the sediments that
contain vivianite.
The succeeding sedimentary units lack the distinc-
tive clayey siltstones at the top of each diatomaceous
siltstone sequence and contain fewer leaf fossils than
the deposits of Stage C. Diatoms are relatively
abundant and there is evidence for continued diatom
cyclicity. Overall, planktonic taxa reach their peak at
the top of Stage D (Dii = top of Unit 21) with a flora
dominated by C. iris var. ovalis. In contrast, substage
Di is dominated by S. construens, an alkaliphilic
epiphyte capable of living in the plankton of shallow
lakes (Gasse 1986). Although this latter taxon
suggests shallow conditions, proceeding upwards in
the profile, planktonic diatoms are also present and
display an percentage increase within Units 19 and 21,
although there is an decline through Unit 20. Data for
pH suggests consistent values of about 7.6 for
substage Di, falling to about 7.1 in Dii.
In Stage E there are again peaks in planktonic
diatom percentages at the top of each of the
sedimentary units (22–27) although the floras are
now also characterized by the presence of C. iris and
C. elymaea. Cyclotella iris occurs in the bottom mud
or phytoplankton of alkaline lakes (Gasse 1986). The
ecological requirements of the C. elymaea are
uncertain given its extinct status, although Ecomo-
mou-Amilli (1991) suggested an association with
‘‘higher salinities and alkalinities’’ than were typical
of the Florina-Ptolemais-Kozani Basin lakes. Trans-
fer-function data for extant species suggest a pH of
7.3–7.7. Diatom abundances decline slightly, leaf
fossils (and one flower, Fig. 3k) are again common,
and vivianite occurs at several horizons—features
that resemble those of Stage C, but with a less drastic
decline in diatom abundance.
Cyclotella castracanei appears for the first time in
Stage F, which again shows an upward increase in
planktonic floras through Unit 28. The pH data
indicates a decline from about 7.7 to 7.2. This inverse
relationship between planktonic diatoms and pH is
repeated at many levels through the sequence
(Fig. 6). A 3-cm-thick layer of diatomaceous clayey
silt with abundant euhedral bladed anapaite crystals
with a greenish color that form nodules (Fig. 3e)
comprises Unit 29 at the top of Stage F. Stamatakis
(2004) suggested that these nodules (up to 1-cm
diameter) formed diagenetically at the expense of
vivianite when exposed to Ca2? and HCO3--rich
meteoric waters and/or somewhat acidic groundwa-
ter. This level in the sequence is also associated with
a moderate drop in lake water pH according to the
diatom record.
Light grey siltstones dominate through the remain-
der of the section with occasional pure diatomites
occurring in Units 31 and 33. The flora in Stage
G (lower Unit 30; Fig. 6) shows a shift towards
C. ocellata, a freshwater species that occurs in
shallow water bodies. Transfer-function data indicate
a pH of about 8 to 8.4. Gasse (1986) suggests it is
favored by oligotrophic conditions. Stage G does not
appear to document any increase in the percentage of
planktonic taxa with height through the section.
However, Stage H does display an increase in plank-
tonic diatoms, as well as a switch from C. ocellata
to A. ambigua. This planktonic species is favored
by relatively shallow water and low alkalinity
(\5 meq l-1) (Owen and Utha-aroon 1999) with
derived pH values of about 7.5–8.
Stage I contain only rare and broken diatoms in a
light grey siltstone (Unit 34) and in streaky white
siltstones in a grey siltstone (Unit 35). Anapaite
nodules are scattered throughout this latter deposit,
which suggests post depositional alteration of a
vivianite precursor. Collectively, the data document
a possible period of emergence prior to renewal of
aquatic conditions in Stage J. A period of erosion
followed with later deposition of fluvial conglomer-
ates (Fig. 2).
Further data can be derived from chysophycean
stomatocysts, which are common at several levels in
the sedimentary sequence, forming 0–20% of the
total diatom ? cyst assemblage (Fig. 6). These
organisms are most abundant in low productivity
lakes with circum-neutral pH, low alkalinity and low
phosphorous (Ognjanova-Rumenova 2005). Smol
(1985) has used the ratio of diatoms to cysts as an
indicator of trophic state. The data for Klidi (Fig. 6)
show that cysts are most common in the lowest part
of the succession (Stage Cii) in sediments with low
diatom abundance. The ratios thus document a period
of oligotrophic conditions. Cysts also tend to be
absent or form a low contribution during periods
when planktonic diatoms were most common perhaps
reflecting periods of increased trophic state.
In general, there appear to be multiple episodes of
diatom cyclicity at varying scales (Fig. 8b). Several
J Paleolimnol (2010) 44:343–359 355
123
diatom stages (C, D, F and H) show an increase in
planktonic diatoms proceeding upwards in the profile.
At a smaller scale, many individual sedimentary units
also tend to show increases in planktonic species. The
floras of the Klidi Quarry are similar to those reported
from Bitola (Fig. 1) in Macedonia (Ognjanova-
Rumenova 2005) where the floras are also dominated
by Cyclotella spp., with common S. construens.
However, no cyclic patterns are reported from that
study, which might reflect variations in local condi-
tions or, perhaps more likely, the wider sampling
interval (17 samples from about 63 m of core), which
produced a less detailed diatom record. In the same
study, Ognjanova-Rumenova (2005) also pointed out
that the appearance of C. castracanei and disappear-
ance of Miocene Actinocyclus marked the lower part
of the Pliocene, which in the section reported here
occurs in Stages F–G.
Environmental conditions in the Kozani Basin
The lower Neogene of the Kozani Basin is
represented in our sampling set by the Kariditsa
sedimentary sequence (Figs. 2 and 7). These depos-
its are a complex mix of claystones, siltstones, and
minor lignite. Gastropods are present in many
horizons. Diatoms are absent from about 50% of
the sequence and occur at three major levels.
Benthonic floras that give way to an increasing
number of epiphytes dominate Stages A–D. The pH
ranged between about 6.8 and 7.8, somewhat lower
than pH data for the Klidi area. Diatoms are absent
in Stage E and reappear with a mixed benthonic-
epiphytic flora and common Eunotia spp., which
indicate even lower pH values (6.6–7.2). Diatoms
are absent in Stage H, with a sparse flora domi-
nated (up to 100%) by A. sphaerophora character-
izing Stage I. This taxon is usually cited as an
indicator of shallow water bodies with a medium to
high alkalinity ([10 meq l-1). It also occurs in
hyperalkaline settings.
In general, the data indicate that the Kariditsa
sediments formed under very shallow acidic to
neutral water, with several periods of desiccation
and emergence occurring. These environments would
also have been favorable to the development of peaty
swamps and the formation of the lignite parts of the
succession. Towards the end of the depositional
period there was a shift towards more alkaline
conditions, perhaps reflecting evaporative concentra-
tion and/or a nearby spring water source.
The upper Neogene sequences contain evidence of
both high and moderate salinity conditions. Calvo
et al. (1995) have noted the occurrence of magnesite
along with huntite, hydromagnesite and dolomite at
several locations in the Kozani Basin. Outcrops on
the southern (KP1, Stena Portas) and eastern (KM1
and KM2, Neraida; Fig. 1) margins of the area
contain extensive deposits of primary and reworked
huntite and magnesite. These appear to have formed
in small spring-fed saline lakes on the margins of a
larger, fresher water body (Fig. 8c). The Neraida
outcrops, for example, contain extensive beds of fine-
grained snow-white huntite/magnesite with minor
aragonite and magnesite, associated aragonitic tufa
mounds and local stromatolites. The magnesium-rich
deposits contain a sparse, fragmented diatom flora
dominated by shallow-water epiphytic and benthic
taxa that would be incompatible with a highly saline
environment. These diatoms may therefore have been
transported into the saline lakes from adjacent
swampy areas or formed part of a freshwater river
flora. Epiphytic Cymbella spp. are more abundant and
dominate, together with E. sorex, in the overlying
carbonate and diatomaceous siltstone units (Fig. 2),
documenting shallow-water sedimentation. Diatoms
at these higher levels are also more varied and
abundant suggesting extensive freshwater conditions.
Section KP1 (Figs. 1 and 2) at Stena Portas also
contains magnesium-rich chemical sediments. Calvo
et al. (1995) noted the presence of dolomicrite and
marl that formed in fresh aquatic environments and
attributed the presence of huntite to small saline
lakes, probably similar to those near Neraida.
Reworked huntite was likely eroded from these
ponds and incorporated in deltaic facies entering a
larger water body. Diatoms are generally absent in
the Stena Portas deposits, except near the base of
the sequence where C. aegeae, C. elymaea and
N. frustulum, together with A. sphaerophora and
Thalassiosira sp. 1. The first two of these species
are known from the fossil record and have poorly
understood ecologies, although Ecomomou-Amilli
(1991) noted that C. elymaea was associated with
chemical sediments suggestive of higher salinities.
N. frustulum occurs in a variety of settings, but
A. sphaerophora is suggestive of higher salinities
and alkalinities.
356 J Paleolimnol (2010) 44:343–359
123
Conclusions
The Late Miocene through Pliocene sedimentary
rocks of the Florina-Ptolomeis-Kozani Basin include
lithofacies of biological, chemical, and detrital origin.
These host six distinct diatom groups and several
subgroups in cluster analyses that appear to be related
to the type of sediments in which they are found.
Group 1 was associated with very pure diatomites and
comprised mainly A. ambigua, while highly diato-
maceous deposits tended to be associated with Group
4 diatoms (mainly C. elymaea and C. ocellata).
Group 2 (Cyclotella spp. and Fragilariaceae, and
other taxa) and Group 3 (two unidentified Cyclotella,
plus C. iris var. cocconeiformis, C. iris var. integra,
and A. distans) were present in diatomaceous silt-
stones. Group 5 (A. sphaerophora, Navicula sp. 5)
was associated with claystones. Group 6 is dominated
by varied benthic and epiphytic taxa and was found in
siltstones that were locally rippled and/or also
contained gastropods. Group 6b appeared to be
present where chemical sediments such as huntite
also occurred.
The Klidi section (Florina Basin) consists of
diatomaceous siltstones and diatomites that rest on
a thick sequence of lignites and siltstones. The older
lignitic succession formed on a floodplain with
backswamps. Cyclotella spp. and a variety of Frag-
ilariaceae dominate the stratigraphic section, with
A. ambigua being abundant towards the top of the
sequence. These diatoms record a series of lake
expansions and contractions that occurred on at least
two time scales that may reflect the influence of
precession and eccentricity cycles as noted by
Steenbrink et al. (2006). Biostratigraphic data for
the diatoms suggest that the Mio-Pliocene boundary
lies within diatom stages F and G. Chysophycean
stomatocysts suggest periods of oligotrophic condi-
tions, particularly towards the base of the Klidi
sequence.
The Kozani Basin includes both lower and upper
Neogene deposits. The former were characterized by
siltstones, claystones and lignites with predominantly
epiphytic and benthic diatom floras that document
shallow-water deposition under acidic to neutral pH
conditions. Environments became alkaline at the top
of the succession. The upper Neogene includes
several chemical lithofacies that reflect sedimentation
in small saline lakes. Diatoms and sedimentological
data also indicate the occurrence of local shallow
freshwater environments and springs that probably
discharged alkaline waters into the former lakes.
Acknowledgments The authors thank Alison Lee for her
work on preparing diatom slides. Owen was supported by a
Hong Kong Baptist University Grants (FRG/06-07/I-28 and
FRG/08-09/II-25). Renaut was supported by the Natural
Sciences and Engineering Research Council of Canada,
Discovery Grant 629-2008. Stamatakis received funding from
the University of Athens.
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