background image

GEOLOGICA CARPATHICA, 50, 6, BRATISLAVA, DECEMBER 1999

449–458

THE PALEOGENE HISTORY OF THE PELAGONIAN ZONE S. L.

(HELLENIDES, GREECE): HEAVY MINERAL STUDY

FROM TERRIGENOUS FLYSCH SEDIMENTS

PETER FAUPL

1

, ANDREAS PAVLOPOULOS

2

 and GEORGE MIGIROS

2

1

Institute of Geology, Geocenter, Vienna University, Althanstraße 14, A-1090 Vienna, Austria; peter.faupl@univie.ac.at

2

Laboratory of Mineralogy-Geology, Agricultural University, Iera odos 75, GR-11855 Athens, Greece;

apvlo.@auadec.aua.gr, bagm@auadec.aua.gr

(Manuscript received October 19, 1998; accepted in revised form September 28, 1999)

Abstract:

 The terrigenous material of the flysch of the Pelagonian Zone s.l. of the Internal Hellenides in Pelion,

Skopelos, Euboea, Othrys Mountain and Argolis have been characterized by their heavy mineral assemblages, based
on 114 samples. The terrigenous input can be divided into a garnet-dominated association, restricted to flysch sedi-
ments of both western Othrys and Ligourion (Argolis), and assemblages with variable amounts of the stable ZTR
group (zircon, tourmaline, rutile) and apatite, found at all the other localities. The garnet assemblage is assumed to
have been derived from mica schist complexes existing at the western margin of the Pelagonian microcontinent,
tectonically active due to the closure of the Pindos Ocean. The situation is similar to that already known from the
Pindos and Parnassos-Ghiona zones. Blue amphiboles detected in western Othrys witness the existence of blueschist
terrains. The ZTR-apatite group points to a different source province, not connected regionally with the former source.
The activity of this source terrain can be related to the closure of a Neotethyan ocean in the Vardar Zone, along the
eastern margin of the Pelagonian Unit, during the early Tertiary. The heavy mineral assemblages indicate that in this
source area ophiolitic complexes are tectonically incorporated to a lesser extent. Blueschists seem to be absent, as no
detrital blue amphibole was found.

Key words:

 Hellenides, Pelagonian Zone, Paleogene, terminal flysch, heavy minerals.

Introduction

The Pelagonian Zone belongs to the Internal Hellenides
(Brunn 1956) and is tectonically situated between the Exter-
nal Hellenides (Paxos, Ionian, Gavrovo-Tripolitza, Pindos,
Parnassos-Ghiona zones) and the Vardar-Axios Zone (Fig. 1).
The Pelagonian zone s.l. is subdivded into an unmetamor-
phosed western and a metamorphosed eastern part. The un-
metamorphosed part is called the Subpelagonian Zone
(Aubouin 1959) and comprises Othrys Mountain and the Ar-
golis peninsula, including the islands of Aegina, Poros and
Hydra. According to the same author, the metamorphosed
units are exposed in Thessaly, Pelion, in parts of Euboea, and
on several islands, such as the Northern Sporades.

Paleogeographically, the Pelagonian Zone can be consid-

ered as a microcontinental fragment of the Cimmeria conti-
nent between two oceanic domains (Mountrakis 1985; Pa-
panikolaou 1986): the Pindos Ocean towards the west (see
also Robertson et al. 1991; Jones et al. 1992) and the Vardar
Ocean in the east (see also Bernoulli & Laubscher 1972;
Godfriaux & Ricou 1990). From Middle Jurassic times on,
the closure of the oceanic domains started, with accompany-
ing ophiolite obduction contributing to the development of
the Pelagonian Zone (Godfriaux & Mercier 1965; Katsikat-
sos et al. 1982). The final closure of both the oceanic do-
mains occurred in early Tertiary times (e.g. Robertson 1990;
Jones & Robertson 1991) and was accompanied by flysch
sedimentation. Ideas about the origin of certain ophiolites de-
pends strongly on the favoured tectonic concept.

The Pelagonian Zone s.l. is characterized, in general, by a

common development (e.g. Mountrakis 1985; Katsikatsos
1992). Above a Hercynian basement, Early Paleozoic sediments
were deposited, followed by a volcano-sedimentary succession
of Early Triassic age and a Middle Triassic to Liassic shallow-
water limestone (Pantokrator Limestone; Renz 1955) as well as
related intra-platform and marginal carbonate sequences. Dur-
ing the Jurassic, the basin deepened and radiolarite fomations
appeared. In this period the obduction of ophiolite complexes
occurred accompanied by deep-water clastic sedimentation. Af-
ter a period of superficial exposure, this tectonically composite
succession was transgressed by the sea from mid-Cretaceous
times on (Cenomanian-Turonian transgression). A widespread
Late Cretaceous rudist-bearing shallow-water limestone facies
covered the whole Pelagonian realm. A marginal facies (Ermio-
ni Limestone, Poros Formation) of the Late Cretaceous shallow-
water platform has been reported from the eastern Argolis and
Poros island (Clift & Robertson 1990). From the Maastrichtian
on, the carbonate platform collapsed. On down-faulted regions,
pelagic limestones were deposited, while uplifted parts suffered
erosion and partial karstification. During the Paleocene and
Eocene terrigenous deep-water sediments spread over the whole
Pelagonian Unit. The sedimentary evolution of the Pelagonian
Zone ceased with these flysch deposits, which are the response
to the Paleogene compressional deformation in the Hellenides.

In the present paper, the authors contribute new data to the

discussion about the paleogeographic position of the source
terrains of the vast mass of terrigenous flysch sediment in the
Pelagonian realm and also try to give some information

background image

450                                                                    FAUPL,  

 

PAVLOPOULOS 

 

and  MIGIROS

about the composition of these source areas. Although heavy
mineral studies are an appropriate tool for such investiga-
tions; the method has not been systematically utilized until
now in this internal part of the Hellenides. These investiga-
tions, based on microscopical examinations, give a first in-
sight into the heavy mineral distributions, but the authors are
aware that further detailed mineralogical and chemical stud-
ies on several of the minerals would markedly increase the
information about the source terrains.

Geological setting and sample locations

The heavy mineral composition of the Paleogene terrige-

nous flysch deposits of the Pelagonian Zone s.l. have been

investigated in 11 regions, shown in Fig. 1. The stratigraphic
charts of Fig. 2 exhibit the Cretaceous to Paleogene geologi-
cal evolution. Detailed biostratigraphic information about the
flysch sediments is relatively sparse in some regions, espe-
cially about the range of the flysch successions. Only their
stratigraphic onset has been relatively well documented (e.g.
Richter et al. 1996).

In Othrys Mountain, a western, northeastern and eastern

sample group were investigated. In the western region, to-
wards the north of Domokos (Fig. 1-1), the Paleocene to
Eocene Dhirvi Formation (Smith et al. 1975) started with a
stratigraphic gap in the Early Paleocene (Richter et al. 1996)
above the karstified relief of the Upper Cretaceous carbonate
platform (Goura Formation, Smith et al. 1975). In eastern
Othrys Mountain, in the sectors of Neraida Anavra (Fig. 1-2a),

Fig. 1.

 Geological sketch map of the Hellenides showing the position of the flysch sample groups. 1 — western Othrys Mountain, two

sections to the north of Domokos; 2a — northeastern sector of the Othrys Mountain, region of Neraida-Anavra; 2b — eastern sector of
the Othrys Mountain, regions of Vrinena-Ag. Joannis and Kofi-Kokkoti; 3 — exposure at the national road near Ag. Georgios, in the Vo-
los region; 4 — Pelion, “Flysch of Plesidi”; 5 — Skopelos island, lower tectonic Pelagonian Unit in the central part of the island; 6 —
Skopelos island, upper tectonic Palouki Unit in the eastern part of the island; 7a — Euboea, roadcut at the national road between Psachna
and Aghios Pass; 7b — Euboea, region of Kimi; 8 — Argolis, NE Ligourion; 9 — Argolis, southern part of Methana peninsula; 10 — Ar-
golis, Adheres peninsula; 11 — Poros island.

background image

THE  PALEOGENE  HISTORY  OF THE  PELAGONIAN  ZONE  S.L.  (GREECE)                                 451

Fig. 2.

 Stratigraphic columns schematically showing the Cretaceous and Paleogene geological evolution in the sampling regions.

background image

452                                                                    FAUPL,  

 

PAVLOPOULOS 

 

and  MIGIROS

Vrinena-Ag. Joannis and Kofi-Kokkoti (Fig. 1-2b), a transi-
tional contact between the limestones of the Goura and the
Dhirvi Formation exists (Migiros & Pavlopoulos 1993). The
true terrigenous flysch sediments lying upon the transitional
facies, commenced in the Late Paleocene and passed up into
the Eocene (Richter et al. 1996).

Along the national road near Aghios Georgios (Fig. 1-3),

west of Volos, a low-grade metamorphic flysch succession
has been examined in roadcuts. The Upper Cretaceous Pelag-
onian limestone passes with transitional beds of red pelites
into the flysch sediments. The flysch succession of Maas-
trichtian to Paleocene age (Ferriére 1982; Katsikatsos et al.
1986) is mainly composed of pelites and sandstones but also
contains intercalations of clastic limestones.

On the Pelion peninsula, the so-called “Flysch of Plesidi”

(Fig. 1-4) was sampled. This siliciclastic sequence of Maas-
trichtian age is composed of sandy-pelitic beds which also con-
tains red conglomerates and overlies the Cenomanian lime-
stones. The conglomerates contain limestone pebbles and rarely
sandstone elements. The succesion is part of the Plesidi-
Lechonia-Veneto klippe (Ferriére 1982; Katsikatsos et al. 1986).

On the island of Skopelos, three tectonic units occur: Palou-

ki, Glossa and Pelagonian (upper, intermediate, lower respec-
tively; Matarangas & Jacobshagen 1988). The Pelagonian and
Palouki units are crowned by an Upper Cretaceous sequence
of transgressive rudist limestones covered by Maastrichtian to
Paleocene flysch. Between the flysch successions and the un-
derlying Upper Cretaceous limestones, a stratigraphic gap
exists (Matarangas 1992). A volcano-sedimentary formation
(= Glossa Unit), including ultramafic bodies, is intercalated
between the lower (Pelagonian) and upper (Palouki) tectonic
unit. The rocks of the Pelagonian Unit seem to be somewhat
higher metamorphosed than those of the Palouki one. In the
Palouki Unit, the Albian-Cenomanian carbonate platform is
underlain by thin-bedded deep-water carbonates of mainly Ap-
tian–Albian age, which are interbedded with thin siliciclastic
turbidites. The flysch deposits of the Pelagonian Unit (Fig. 1-
5) were investigated in the central part of the island (to the
south and east of Skopelos town), whereas the Palouki Unit
was studied in the eastern part of the island, near the Evange-
lismos Monastery (Fig. 1-6).

The terminal flysch sediments of Euboea developed grada-

tionally from Maastrichtian deep-water limestones, which
are underlain by Upper Cretaceous platform carbonates
(Katsikatsos 1977; Robertson 1990, 1991). The samples
were collected from two locations: along the Psachna-Man-
toudi road (Fig. 1-7a) to the north of Psachna, where the pe-
lagic limestone reaches up to the Early Paleocene, and in the
region of Kimi (Fig. 1-7b), where the flysch deposition had
already commenced in the uppermost Maastrichtian (Richter
et al. 1996). In the Kimi region, the upper part of the flysch
sequence is interleaved with thrust sheets of ultramafic and
mafic rocks as well as Maastrichtian pelagic limestones
(Robertson 1990). Robertson (l.c.) interpreted this as a devel-
opment of a subduction-accretion complex which originated
during the closure of the Neotethyan ocean.

On the Argolis peninsula of the Peloponnese, the terminal

flysch sequences were investigated at three locations: (1) the
flysch succession NE of Ligourion, (2) the flysch exposed in

the roadcuts in the southern part of the Methana peninsula and
(3) flysch outcrops along the coast of the Adheres peninsula
(Fig. 1-8, -9, -10 respectively). The onset of the terrigenous
flysch deposition youngs from east towards the west. The Li-
gourion flysch commenced in the Middle Eocene and is under-
lain by transitional beds of Paleocene to Early Eocene age and
Campanian to Upper Maastrichtian pelagic limestones. The
latter rest upon Cenomanian shallow-water carbonates bearing
rudists and orbitolines (Photiades & Skourtsis-Coroneou
1994; Richter et al. 1996). The flysch sedimentation on the
Methana peninsula and on Adheres seems to have already
started in the Maastrichtian (Bachmann & Risch 1979). The
youngest ages observed in flysch sediments are of the Middle
Eocene (Richter et al. 1996).

On Poros island (Fig. 1-11), a late Cretaceous (Aptian–

Maastrichtian) deep-water slope succession (Bachmann &
Risch 1979; Poros Formation, Clift & Robertson 1990), com-
posed of pelagic carbonates, carbonate-rich turbidites, lime-
stone conglomerates and slump deposits, is overlain by a ter-
rigenous flysch succession, named the Ermioni Complex
(Robertson et al. 1987). The Poros Formation is considered to
be a lateral equivalent to the Upper Cretaceous carbonate plat-
form (Akros Limestone). In the terrigenous flysch succession
of the Ermioni Complex, huge neritic limestone olistolites oc-
cur. Illite crystallinity data indicate a very low-grade metamor-
phism, up to a high diagenetic grade, whereas on the adjacent
mainland somewhat higher metamorphic overprinting is re-
ported (Clift & Robertson 1990). The heavy mineral samples
were gathered at the western part of the island (see geological
map of Strauss 1979 in Jacobshagen 1986).

Heavy mineral assemblages

Methods

The heavy minerals were separated from crushed and

sieved sandstone samples (fraction 0.4–0.063 mm) (for de-
tails see Faupl et al. 1998). The carbonate minerals were dis-
solved in acetic acid. Tetrabromoethane (

ρ 

= 2.96 g.cm

-3

)

was used for the gravitational separation procedure. After
mounting the heavy minerals in Canada Balsam, the translu-
cent minerals were examined under the petrographic micro-
scope. Using the ribbon counting method, more than 200
heavy minerals were counted from each sample. In many
cases the heavy minerals examined only microscopically rep-
resent mineral groups, such as the tourmaline group, garnet
group, chrome spinel group etc. In cases of large sample
numbers, a cluster analysis was used to differentiate heavy
mineral assemblages in an objective manner. For the statisti-
cal procedure, the software package WinSTAT

®

, ver. 3.0

(Kalmia Com. Inc., Cambridge MA, 1994) was used. The
stepwise formation of the clusters was done by the incremen-
tal sums of square (Ward’s method).

The data regarding heavy mineral composition in grain-%

and the coordinates of sample locations are available in the
Editorial Office or from the authors.

background image

THE  PALEOGENE  HISTORY  OF THE  PELAGONIAN  ZONE  S.L.  (GREECE)                                 453

Othrys Mountain

In Othrys Mountain, the western sampling groups, to the

north of Domokos, are clearly distinguished from the north-
eastern and eastern locations (Fig. 3). These western assem-
blages are strongly garnet-dominated (av. > 80 %) and contain
about 10 % of the stable group (zircon–tourmaline–rutile). Ap-
atite, with few exceptions, is below 10 %. Garnet is frequently
accompanied by minor amounts of staurolite and traces of
chloritoid. The abundance of blue amphiboles as an indicator
mineral for blueschist rocks in the source terrain is of specific
interest. Normally, these conspicuous minerals occur only in
traces; but in one sample, their content rises up to 10 %. West-
ern Othrys was the only part within the Pelagonian realm in-
vestigated where these detrital blue amphiboles were frequent-
ly observed. Detrital chrome spinel has been detected only in
very minor percentages within the western sector.

Towards the east, the garnet content diminishes dramatically

to below an average of 2 % (Fig. 3). The northeastern sam-
pling sites, with an average of about 8 %, follows the same
trend. Only a few samples from these eastern sites show a still
relatively high garnet content (cluster C in Fig. 3). The sand-
stones from the easternmost region of the Othrys Mountain are
mainly characterized by the predominance of the stable ZTR
group (cluster D, Fig. 3) or apatite (cluster B, Fig. 3). Detrital
chrome spinel increases towards the east reaching average val-
ues of 31 % in cluster C and 15 % in D (Fig. 3).

Fig. 3.

 Average heavy mineral composition of 4 major clusters (A, B, C, D) of the flysch sediments on the Othrys Mountain, separated by

a cluster analysis (WinSTAT

®, ver. 3.0). The contribution of the individual clusters to the sample locations is shown.

Aghios Georgios (Volos region)

From these flysch meta-sediments only two samples (Fig. 4)

were gathered in order to see some changes due to metamor-
phism within the assemblages. The sandstones are character-
ized by the ZTR group and apatite. All the other heavy min-
erals, such as garnet and chrome spinel, occur in traces.

Pelion peninsula—“Flysch of Plesidi”

The heavy mineral composition of the samples from outcrop

pe-132 (Fig. 4) is very similar to that of the eastern Othrys, with
a clear predominance of the ZTR group and apatite and minor
percentages of garnet. Detrital chrome spinel rises up to nearly
20 %. The red conglomerates, which obviously do not belong to
a deep-water succession, are strongly apatite-dominated (av. 74
%) with a garnet content of max. 3 %.

Skopelos island

The terminal flysch deposits of both the upper (Palouki)

and lower (Pelagonian) tectonic units (Fig. 5) are dominated
by the stable ZTR group and are practically free of garnet
(av. < 1 %). Chrome spinel occurs only with a host of av. < 1
% in the Pelagonian Unit, whereas, in the Palouki Unit, the
average is somewhat higher (2.6 %, max. 7 %). Apatite is ob-
served, in most cases, as a major constituent.

background image

454                                                                    FAUPL,  

 

PAVLOPOULOS 

 

and  MIGIROS

On the basis of a cluster analysis, it is demonstrated that

four types of heavy mineral assemblages contribute to the
terrigenous material of the flysch sandstones exposed in the
Skopelos island (Fig. 5). The Pelagonian Unit consists of

> 60 % of samples with heavy mineral associations rich in
zircon and very small percentages of apatite (cluster A, Fig.
5). These zircon-rich associations are charcteristic for the
Pelagonian Unit only, whereas assemblages with nearly
equal amounts of zircon and apatite (cluster B, Fig. 5) and
apatite-rich assemblages (cluster C, Fig. 5) are of much low-
er frequency. The terminal flysch of the Palouki Unit is com-
posed of heavy mineral assemblages type B, C and D (Fig.
5). The D-type heavy mineral association, rich in rutile, has
not been observed in the Pelagonian Unit.

In the turbiditic sandstone intercalations of Early Creta-

ceous age from the Palouki Unit, only rutile-rich (cluster D,
Fig. 5) and apatite-dominated heavy mineral assemblages
(cluster C, Fig. 5) have been observed.

Euboea

The heavy mineral composition is dominated by the ZTR

group and apatite (Fig. 4). The content of chrome spinel is
below 10 %. Other components, such as garnet, play only a
subordinate role. Differences between the two sampling lo-
cations are visible in the amount of rutile and tourmaline,
which are more abundant in the Psachna–Aghios Pass Road,
whereas apatite is more frequent in the Kimi region. Zircon
is nearly equal distributed in both locations.

Argolis peninsula

The terminal flysch sediments of Ligourion are clearly dis-

tinguished from the other Argolis locations by their high per-
centages of garnet (av. 63 %) accompanied by apatite and a
low content of the ZTR group (Fig. 6). Chrome spinel is only
detected in traces. These heavy mineral assemblages are com-
parable with those of the western Othrys, only with the excep-
tion that blue amphiboles were not found in the Ligourion fly-
sch. In the Adheres sample group, only a few samples with
such an elevated amount of garnet were observed. The Ligou-
rion samples belong completely to cluster A (Fig. 6).

The Methana sample group comprises mainly heavy min-

eral associations of cluster B (nearly equal percentages of the
ZTR group and of apatite, Fig. 6) and only a few of cluster C
(predominance of apatite with relatively high tourmaline).
The samples from the Adheres peninsula belong predomi-
nantly to the apatite-rich type of cluster C (Fig. 6), whereas a
few samples correspond to clusters A and B. Detrital influ-
ence of chrome spinel is in both the Methana and Adheres lo-
cations higher than in the Ligourion flysch. The highest
chrome spinel values are observed in cluster B-type associa-
tions (av. 5 %, max. 9).

Poros island

The three samples from the terminal flysch, characterized by

high percentages of the ZTR group and apatite (Fig. 4), are in
good correspondence with the samples collected in the south-
ern part of the Methana peninsula (Fig. 6, cluster B). In con-
trast, the turbiditic interlayers within the Poros Formation con-
tain very high values of chrome spinel (av. 85 %) accompanied
by only a few percentages of garnet and apatite (Fig. 4).

Fig. 4.

 Average heavy mineral composition of the terminal flysch

sediments of Aghios Georgios (Volos region) (3), Pelion peninsula
—”Flysch of Plesidi” (4), Euboea (7) and Poros island (11). For
explanation of ornament see Fig. 3.

background image

THE  PALEOGENE  HISTORY  OF THE  PELAGONIAN  ZONE  S.L.  (GREECE)                                 455

On the source terrains of the Pelagonian flysch

sandstones

On the basis of heavy mineral studies, two major source

provinces have been distinguished. The garnet-dominated
flysch deposits of western Othrys and Ligourion were sup-
plied from a crystalline basement complex predominantly of
medium to high metamorphic grade, indicated by garnet and
staurolite. Mica schist complexes seem to play an important
role. The abundance of blue amphiboles in the western Oth-

rys gives evidence of the existence of blueschists as part of
this metamorphic terrain which had already been exposed
during the Paleocene (Faupl et al. 1996). The traces of detri-
tal chloritoid could derived from these high-pressure rock
complexes. Otherwise, ophiolitic complexes were only of
minor importance in the composition of this source terrain,
as indicated by the low percentages of detrital chrome spinel.

All the other sample locations of the Pelagonian Zone s.l.

are characterized by the predominance of stable heavy min-
erals of the ZTR group and of apatite. For these assemblages,

Fig. 5.

 Average heavy mineral composition of 4 major clusters (A, B, C, D) of the flysch sediments on Skopelos island, separated by a

cluster analysis (WinSTAT

®

, ver. 3.0). The contribution of the individual clusters to the lower (Pelagonian) and upper tectonic (Palouki)

unit is shown. For explanation of ornament see Fig. 3.

Fig. 6.

 Average heavy mineral composition of 3 major clusters (A, B, C) of the flysch sediments on Argolis peninsula, separated by a

cluster analysis (WinSTAT

®

, ver. 3.0). The contribution of the individual clusters to the sample locations is shown. For explanation of or-

nament see Fig. 3.

background image

456                                                                    FAUPL,  

 

PAVLOPOULOS 

 

and  MIGIROS

principally two explanations are possible: (1) The stable
heavy mineral associations are the products of post-sedimen-
tary processes of passive enrichment, such as the dissolution
of unstable minerals during burial diagenesis or metamor-
phism (for stability sequence during burial see Mange &
Maurer 1991). (2) These heavy mineral associations mirror,
to a broad extent, the petrological composition of a hinter-
land mainly composed of granitoid rock complexes.

The feldspar-rich composition of the sandstones seems to

be a clear indication for the occurrence of feldspar-bearing
rocks as major constituents of the source area. Therefore, it
can be assumed that the stable heavy mineral associations of
the Pelagonian flysch sandstones actually reflect a granitoid
hinterland and that post-sedimentary alterations are only of a
minor degree. Garnet-bearing rocks, such as mica schist
complexes, accordingly, were not of great significance in this
source terrain. Only a few exceptions have been observed in
the eastern parts of the Othrys and in the Argolis. Ophiolitic
rocks, especially ultramafic series, indicated by detrital
chrome spinel, appear to have been somewhat more repre-
sented in the source of the stable assemblages than within the
garnet-dominated one (western Othrys, Ligourion). A large
part of the ophiolites obducted during the Late Jurassic and
Early Cretaceous were covered during Paleogene, as can be
documented on Poros island, where Cretaceous formations
bear high amounts of chrome spinel while the Paleocene fly-
sch resting above has only very small amounts.

The heavy mineral stability during progressive metamor-

phism, especially of detrital chrome spinel or garnet, is hard
to estimate, but is of great importance for the interpretation
of the heavy mineral assemblages in several regions. In other
words, is the stable composition of the heavy minerals, wide-
ly distributed in the Pelagonian Zone s.l., the product of
metamorphic alterations? An estimation appears to be possi-
ble on Skopelos island, where two tectonic units, both with
similar heavy mineral associations, occur and where the low-
er tectonic unit had obviously experienced a somewhat high-
er metamorphism (Matarangas 1992), clearly seen in the
field. Looking at the distribution of detrital chrome spinel,
the upper tectonic unit contains somewhat more percentages
than the lower tectonic unit, so that a decrease of chrome
spinel with progressive metamorphism could be supposed.
Otherwise, such a trend is not visible for detrital garnet. In-
vestigations on the stability of accessory chrome spinels
within serpentinites in the Alps during progressive metamor-
phism by Burkhard (1993) demonstrate that the degree of al-
teration depends highly on spinel chemistry. Fe-rich Cr-
spinels are subject to alteration, whereas Fe-poor Cr-spinels
are more resistant. The presence of CO

2

 is also an important

factor. Therefore, we can conclude that a loss of detrital
chrome spinel during metamorphism, to a minor extent, has
to be expected, but a total elimination of these detrital miner-
al grains is rather unlikely. There is a good reason to assume
that the stable heavy mineral assemblages reflect largely the
primarily composition of the hinterland and that post-deposi-
tional dissolutions altered the composition of the terrigenous
material to only a minor extent.

Summarizing, two major source provinces for the terrige-

nous material of the Pelagonian flysch sediments can be dis-

tinguished: (1) western flysch succession, such as western
Othrys and the flysch of Ligourion/Argolis were supplied
from a mainly metamorphic source terrain, rich in mica
schist complexes, whereas (2) all the other locations derived
their material predominantly from a granitoid source.

The Early Tertiary paleogeographic evolution

of the Pelagonian realm

According to the Paleocene and Eocene deformational pro-

cesses within the internal Hellenides, the sedimentary evolu-
tion of the Pelagonian domain s.l. is characterized by a re-
markable change from a pelagic limestone facies into a
terrigenous flysch. The two major heavy mineral assemblag-
es discovered in the flysch sediments of the Pelagonian do-
main may indicate that two regional different source terrains
supplied these flysch sediments. The flysch deposits of the
western Othrys Mountains and of Ligourion are clearly dis-
tinguished from the other sample locations by their garnet-
dominated assemblages. Although no paleocurrent informa-
tion are available, a source area at the western active margin
of the Pelagonian microcontinent can be assumed (Fig. 7).
The convergent tectonic activities at this western margin, in
accordance with the final closure of the Pindos Ocean (e.g.
Robertson et al. 1991), situated paleogeographically to the
west of the Pelagonian Unit, caused the uplift of basement
rocks which acted as the western source terrain of the Pelag-
onian Zone. From the same source province, huge masses of
flysch sediments of the Pindos and Parnassos-Ghiona zones
were derived, also characterized to a large extent by garnet-
rich heavy mineral assemblages (Faupl et al. 1994, 1998).
The closure of the Pindos Ocean was also accompanied by
the obduction of ophiolitic complexes, such as the Pindos
Ophiolites (Kemp & McCaig 1984; Jones & Robertson
1991), now resting upon Tertiary flysch sediments. In the ter-
minal Pindos flysch, a massive influx of ophiolitic detritus
occurred approximately from Middle Eocene time on, where-
as the older sediments are mostly garnet-dominated. The
heavy mineral composition of the flysch sediments of the
western Othrys and of Ligourion are largely in good accor-
dance with the lower part of the Pindos flysch sediments. In

Fig. 7.

 Sketch depicting the paleotectonic position of the two ma-

jor source terrains of the terminal flysch sediments of the Pelago-
nian Zone s.l. during the Paleocene–Eocene (not to scale).

background image

THE  PALEOGENE  HISTORY  OF THE  PELAGONIAN  ZONE  S.L.  (GREECE)                                 457

the Pindos flysch successions, especially in the central and
southern Pindos Zone, detrital blue alkali amphiboles have
been observed, which are also quite frequent in the western
Othrys Mountain (Faupl et al. 1996).

The major part of the Pelagonian flysch sediments, charac-

terized predominantly by different mixtures of the ZTR
group and apatite, points to a further source province, not re-
gionally connected with the former source. The activity of
this source terrain can be interpreted with the closure of a
Neotethyan Ocean in the Vardar Zone along the eastern mar-
gin of the Pelagonian Unit during the Early Tertiary (Fig. 7),
as has been described in models by Clift & Robertson (1989)
for the flysch of the Ermioni Complex on the Argolis penin-
sula and Poros island, as well as for the flysch sediments at
Euboea island (Robertson 1990). In this model, an accretion-
ary prism of flysch sediments was emplaced along the col-
lapsed eastern margin of the Pelagonian Zone and shifted
further to the west with increasing compressional deforma-
tion. Ophiolitic complexes are tectonically incorporated to a
lesser extent, and had have only a minor and local influence
on the composition of the Tertiary heavy mineral assemblag-
es, as can be especially documented on Euboea, Poros and
Adheres. On Poros island, in contrast, the turbiditic detritus
of the Cretaceous Poros Formation was dominantly supplied
from ophiolitic sequences.

In the detritus derived from the proposed eastern source

province, an indication for blueschist rocks has not been de-
tected until now, although the formation of Eo-Alpine blue-
schists have been reported from the innermost part of the
Hellenides, such as the Peri-Rhodopian Zone (Michard et al.
1994a,b). For this reason, we are not longer convinced, as
Faupl et al. (1996) supposed, that these very internal zones
were the source for the detrital blue amphiboles in the west-
ern Othrys. We rather believe that the source of the terrige-
nous material of the western Othrys, including the blueschist
detritus, was situated somewhere at the western margin of
the Pelagonian Zone and that the blue amphibole detritus of
the Pindos Zone had practically the same source.

In the model shown in Fig. 7, the regional differences in

heavy mineral composition were explained by the existence
of two active continental margins of the Pelagonian micro-
continent which operated as source terrains at approximately
the same time. However, these two source areas do not nec-
essarily imply that two clearly separated, parallel flysch ba-
sins existed in the Pelagonian Zone.

Conclusions

During Paleocene and Eocene times, terrigenous flysch

sedimentation was distributed in the whole Pelagonian Zone
s.l., in accordance with the Mesohellenic compressional tec-
tonics. The terrigenous input can be divided into a garnet-
dominated heavy mineral assemblage, restricted to flysch
sediments of western Othrys and the flysch of Ligourion, and
associations with variable amounts of the stable ZTR group
and apatite, from all the other locations investigated.

The garnet assemblage, only observed in western loca-

tions, is assumed to has been derived from a source at the

western margin of the Pelagonian microcontinent, tectonical-
ly active due to the closure of the Pindos Ocean. Comparable
heavy mineral associations, rich in garnet, are already known
from the paleogeographically adjoining Pindos and Parnas-
sos-Ghiona zones.

The stable heavy mineral assemblages seem to principally

reflect the primary composition of a predominantly granitoid
source situated at the eastern margin of the Pelagonian realm,
where flysch sedimentation occurred within an accretionary
belt interrelated with the closure of the Neotethyan Ocean
(Clift & Robertson 1989; Robertson 1990).

Ophiolite complexes as a source for the Pelagonian flysch

sediments generally played a subordinate role. An alteration
and reduction of the indicator mineral chrome spinel by low-
grade progressive metamorphism in several regions of the
Pelagonian Zone has to be expected, but probably only to a
minor extent. Blueschist complexes were only exposed in the
western source province, which also supplied the Pindos
Zone with this typical high-pressure detritus.

Acknowledgements:

 The authors thank the authorities of

the University of Vienna and the Agricultural University of
Athens for their financial support during field work. R. Faupl
is thanked for her substantial help in the field and laboratory
work. L. Leitner is thanked for assistance in preparing the
figures. The paper benefited from the constructive comments
of two anonymous reviewers. H. Rice was helpful in correct-
ing the English text.

References

Aubouin J., 1959: Contribution á l’étude géologique de la Gréce

septentrionale: les confins de l’Epire et de la Thessalie.
Thése, sciences, Univ. Paris

, 1958. Ann. Géol. Pays Hellén.,

10, 1–525.

Bachmann G.H. & Risch H., 1979: Die geologische Entwicklung

der Argolis-Halbinsel (Peloponnes, Griechenland). Geol. Jb.,
B32, 3–177.

Bernoulli D. & Laubscher H., 1972: The palinspastic problem of the

Hellenides. Eclogae Geol. Helv., 65, 107–118.

Brunn J.H., 1956: Contribution à l’étude géologique du Pinde sep-

tentrional et d’une partie de la Macédoine occidentale. Ann.
Géol. Pays Hellén

., 7, 1–358.

Burkhard D.J.M., 1993: Accessory chromium spinels: Their coex-

istence and alteration in serpentinites. Geochim. Cosmochim.
Acta

, 57, 1297–1306.

Clift P.D. & Robertson A.H.F., 1989: Evidence of a late Mesozoic

oceanic basin and subduction-accretion in the southern Greek
Neo-Tethys. Geology, 17, 559–563.

Clift P.D. & Robertson A.H.F., 1990: A Cretaceous Neo-Tethys car-

bonate margin in Argolis, southern Greece. Geol. Mag., 127,
299–308.

Faupl P., Pavlopoulos A., Wagreich M. & Migiros G., 1994: Heavy

mineral studies on certain turbiditic sequences in the Greek
mainland: preliminary results. Bull. Geol. Soc. Greece, 30, 2,
45–56.

Faupl P., Pavlopoulos A., Wagreich M. & Migiros G., 1996: Pre-Ter-

tiary blueschist terrains in the Hellenides: evidence from detrital
minerals of flysch successions. Terra Nova, 8, 186–190.

Faupl P., Pavlopoulos A. & Migiros G., 1998: On the provenance of

flysch deposits in the External Hellenides of mainland Greece:

background image

458                                                                    FAUPL,  

 

PAVLOPOULOS 

 

and  MIGIROS

results from heavy mineral studies. Geol. Mag., 135, 421–442.

Ferriére J., 1982: Paléogéographies et tectoniques superposées dans

les Hellénides internes: les massifs de l’Othrys et du Pelion
(Gréce continentale). Soc. Géol. Nord Publ., 8, 1–970.

Godfriaux I. & Mercier J., 1965: Essai de comparaison des massifs

métamorphiques de Thessalie et de macédoine. Ann. Soc. Géol.
Nord

, 84, 205–221.

Godfriaux I. & Ricou L.E., 1990: Direction et sans de transport as-

sociés au charriage synmetamorphe sur l’Olympe. Abstr. 5th
Congr. Geol. Greece, 43.

Jacobshagen V., 1986: Geologie von Griechenland: Gebrüder Born-

traeger

, Berlin, 1–363.

Jones G., DeWever P. & Robertson A.H.F., 1992: Significance of ra-

diolarian age data to the Mesozoic tectonic and sedimentary
evolution of the northern Pindos Mountains, Greece. Geol.
Mag.,

 129, 385–400.

Jones G. & Robertson A.H.F., 1991: Tectono-stratigraphy and evo-

lution of the Mesozoic Pindos ophiolite and related units,
northwestern Greece. J. Geol. Soc. London, 148, 267–288.

Katsikatsos G., 1977: La structure tectonique d’Attique et de l’île

d’Eubée. Proceed. 6th Coll. Geol. Aegean Region, 1, 211–228.

Katsikatsos G., 1992: Geology of Greece. Athens (in Greek).
Katsikatsos G., Migiros G. & Vidakis M., 1982: Structure

géologique de la région de Thessalie orientale (Gréce). Ann.
Soc. Géol. Nord,

 101, 177–188.

Katsikatsos G., Migiros G., Triantaphylis M. & Mettos A., 1986:

Geological structure of internal Hellenides (E. Thessaly-SW
Macedonia, Euboea-Attica-Northern Cyclades Islands and
Lesvos). 

Geol.

 

Geophys. Res., Spec. Issue

, I.G.M.E., 191–212.

Kemp A.E.S. & McCaig A.M., 1984: Origins and significance of

rocks in an imbricate thrust zone beneath the Pindos ophiolite,
northwestern Greece. In: Dixon J.E. & Robertson A.H.F.
(Eds.): The geological evolution of the Eastern Mediterranean,
Geol. Soc., Spec. Pub.,

 17, 569–580.

Mange M.A. & Maurer H.F.W., 1991: Schwerminerale in Farbe. F.

Enke Verl

., Stuttgart 1–148.

Matarangas D., 1992: Geological investigation of Skopelos Il., N.

Sporades, Greece. Ber. ForschZentrum, Jülich, 2684, 1–157.

Matarangas D. & Jacobshagen V., 1988: The nappe structure of the

North Sporades in Greece. The Glossa unit of Skopelos. KFA
Jülich Gmbh

, 1–16.

Michard A., Coffé B., Liati A. & Mountrakis D., 1994a: Découverte

du faciés schiste bleu dans les nappes du Circum-Rhodope: un

élément d’une ceinture HP-BT éohellénique en Gréce septen-
trionale? C. R. Acad. Sci., Paris, 318, II, 1535–1542.

Michard A., Coffé B., Liati A. & Mountrakis D., 1994b: Blueschist-

facies assemblages in the Peri-Rhodopian zone, and hints for
an Eohellenic HP-LT belt in northern Greece. Bull. Geol. Soc.
Greece

, 30, 1, 185–192.

Migiros G. & Pavlopoulos A., 1993: Observations on the Mesozoic

formations of Vrinena-Kofi region in Othrys Mountain
(Greece). Bull. Geol. Soc. Greece, 28/1, 211–218 (in Greek
with abstract in English).

Mountrakis D., 1985: Geology of Greece. Univ. Studio Press, Thes-

saloniki, 1–207 (in Greek).

Papanikolaou D., 1986: Geology of Greece. Eptalofos Editions,

Athens, 1–240 (in Greek).

Photiades A. & Skourtsis-Coroneou V., 1994: Stratigraphic and pa-

leogeographic evolution of the northern Argolis (Greece) dur-
ing the Cretaceous–Paleogene. Bull. Geol. Soc. Greece, 30, 2,
135–146.

Renz C., 1955: Die vorneogene Stratigraphie der normalsedi-

mentären Formationen Griechenlands. InstGeol. Subsurf.
Res

., 637.

Richter D., Müller C. & Risch H., 1996: Die Flysch-Zonen Griech-

enlands XI. Neue Daten zur Stratigraphie und Paläogeographie
des Flysches und seiner Unterlagen in der Pelagonischen Zone
(Griechenland). Neu. Jb. Geol. Paläont. Abh., 201, 3, 327–366.

Robertson A.H.F., 1990: Late Cretaceous oceanic crust and Early

Tertiary foreland basin development, Euboea, Eastern Greece.
Terra Nova

, 2, 333–339.

Robertson A.H.F., 1991: Origin and emplacement of an inferred late

Jurassic subduction-accretion complex, Euboea, eastern
Greece. 

Geol. Mag.,

 128, 27–41.

Robertson A.H.F., Clift P.D., Degnan P.J. & Jones G., 1991: Palaeo-

geographic and palaeotectonic evolution of the Eastern Medi-
terranean Neotethys. Palaeogeogr. Palaeoclimatol.
Palaeoecol

., 87, 289–343.

Robertson A.H.F., Varnavas S.P. & Panagos A.G., 1987: Ocean

ridge origin and tectonic setting of Mesozoic sulphide and ox-
ide deposits of the Argolis Peninsula of the Peloponnesus,
Greece. Sed. Geol., 53, 1–32.

Smith A.G., Hynes A.J., Menzies M., Nisbet E., Price I., Welland M.

& Ferriére J., 1975: The stratigraphy of the Othrys Mountains,
Eastern Central Greece: a deformed Mesozoic continental mar-
gin sequence. Eclogae Geol. Helv., 68, 463–481.