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Technological Education Institute, 50100 Kila Kozani, Greece


Department of Mineralogy and Petrology, Faculty of Sciences, Comenius University,  Mlynská dolina, 842 15 Bratislava, Slovak Republic

(Manuscript received March 21, 1996; accepted in revised form June 20, 1996)


 The Vourinos Ophiolite Complex, (northern Greece) of Jurassic emplacement, is one of the most intensive-

ly studied Mediterranean ophiolites. A highly depleted upper mantle of harzburgite character (in the basal section
represented by ”basal serpentinites”) was generated in a spreading environment. The harzburgite tectonites are over-
lain by crustal magmatites of cumulate type. In vertical section they gradually change from Ol-rich to Plg-dominated
cumulates. Exploitable chromite concentrations together with newly described mineralization of Pt-group minerals
underline its economical importance.

Key words:

 Hellenides, Mesozoic ophiolites, geodynamic evolution.


Ophiolite complexes represent objects of continual interest to
geologists due to the: a) significance of ophiolites in paleotec-
tonic reconstructions, in addition to, b) their metallogenetic

The well exposed Vourinos Complex (northern Greece) is one

of numerous Mesozoic eastern Mediterranean ophiolites out-
cropping within the Balkan Peninsula (the Vardar Zone ophio-
lites, Pindos, Othris, Chalkidiki etc. — Fig. 1).

The Vourinos Complex represents an ultramafic and mafic

rock sequence outcropping over an area of 200 km


. It is named

after the Vourinos mountain range (reaching l800 m a. s. l.). It is
one of the most intensivelly studied eastern Mediterranean Me-
sozoic ophiolites, and has in the past, served as an example to test
different ideas dealing with ophiolites (Brunn l956; Moores l969;
Moores & Vine 1971; Zimmerman 1972; Jackson et al. l975;
Rassios et al. l983a, b etc.) and their metallogeny (Zachos l954;
Augé l985; Augé & Johan l988).


The Vourinos Complex is located on the western rim of the

Pelagonian massif. The tectonic position of the Vourinos Com-
plex on Early to Mid-Jurassic sediments, which form the Meso-
zoic cover of the Pelagonian Paleozoic metamorphites have been
well described in the past (Brunn l956). To the west, the Vouri-
nos Complex is covered by Tertiary sediments of the Meso-Hel-
lenic trench. Jurassic emplacement of the Vourinos Ophiolite
Complex is supposed (l70–l80 Ma — Spray & Roddick l980).
Just below the lower tectonic contact blocks of metamorphites
(mostly of the greenschist facies) are located. Within them even
lenses of quartz garnet amphibolite bodies occur (Moores l969).

They have been dated as 179 ± 4 Ma (Spray & Rodick 1980).
The stratigraphical top of the complex is represented by Upper
Jurassic radiolarian cherts which overlie the pillow lavas of is-
land arc affinity (Noiret et al. l981; Beccaluva et al. 1984).

These are in turn transgressively overlain by pelagic Upper

Jurassic limestones (Pichon 1976; Mavridis et al. 1979). Gen-
erally Jurassic sediments indicate a continental slope environ-
ment which is followed by the Upper Cretaceous transgres-
sion and molasse deposition (Pichon & Lys 1976).

On the present-day surface the Vourinos Complex is

present in the following partial massifs: South Vourinos,
North Vourinos, Kissavos and Krapa (or West Vourinos —
 Fig. 2). The northern and southern blocks are separated by
W–E trending oblique slip fault which passes near Chromio
(Moores l969). Despite this segmentation of the complex sev-
eral authors rank together ophiolites on the Vermion range on
the eastern side of the Pelagonian massif, with those (Vouri-
nos) of the western side. This suggests that the Pindos, Vouri-
nos and Othris ophiolites once probably formed a single body
more that 120 km in width (Smith 1983).

Past works (Jackson et al. 1975; Harkins et al. 1980; Ross

et al. 1980) have split the Vourinos Complex into two gener-
ally different rock sequences: i) harzburgite tectonites having
the main features of the depleted upper mantle lithologies, and
ii) crustal magmatites placed stratigraphically over harzburg-
ite tectonites (Fig. 3).

Main rock lithologies

Moores (l969) divided the Vourinos Complex into three

zones: ultramafic, transitional and mafic. It was later reexam-
ined by Jackson et al. (1975) who re-divided the complex into
the following two parts:

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12                                                                                SAVVIDIS  and  HOVORKA


 stratiform peridotite-gabbro complex, and


 highly deformed harzburgites and dunites (= harzburgite


Within the Vourinos Complex the following main litholo-

gies (Pl. I) can be distinguished:

— Basal serpentinites form the lowermost section of the Vouri-

nos Complex. They are represented by a unit tens to several hun-
dred meters thick (Moores 1969) which is traceable practically
along the whole lower contact (eastern rim) of the complex.

They pass gradually into the overlying harzburgite tectonites.

The basal serpentinites are characterized by two constitu-

ents: a) by serpentinized harzburgite and dunite blocks of dif-
ferent size and generally oval shape. On their surfaces a very
thin ”skin” composed of relativelly light serpentine (of the liz-
ardite-chrysotile polymorphs) is observed in places. Blocks
”float” in b) serpentinite tectonite which split into small frag-
ments of sharp morphology. No veins/veinlets of chrysotile
asbestos type are present in basal serpentinites.

Fig. 1.

 Geotectonic zones with named Hellenic ophiolites in Greece. Rh — Rhodope Massif; Sm — Serbomacedonian Massif; CR —

Circum Rhodope Zone; Pe — Peonian Zone; Pa — Paikos Zone; Al — Almopias Zone = Vardar Zone; Pl — Pelagonian Zone; Sp — Sub-
Pelagonian Zone; Pk — Parnass-Giona Zone; — Pindos Zone; G — Gavrovo-Tripolis Zone; I — Ionian Zone; Px — Paxos Zone; Au
— Unit Talea Mountains; Oph — Ophiolites; A —  Argolis; E — Euboea; K — Kassandra; Pi — Pindos; T — Therma; Go — Gomati;

 — Othris; Si — Sithonia; So — Soufli; Ver — Vermion; Vol — Volvi; Vou — Vourinos; cen Ch — central Chalkidiki (Mountrakis et

al. 1983).

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For the discussed sequence blocks of limestones/dolostones

which can be seen perfectly outcropping (spring 1996) in the
new road-cut between Chromio and Museum completely en-
closed in basal serpentinite are characteristic (Moores 1969).

— Harzburgite  tectonites, total thickness up to 7 km (Jack-

son et al. 1975) bear all the main features of a strongly deplet-
ed upper mantle sequence which is probably the residuum left
after partial melting of the upper mantle protolith. They form
about 85 per cent of the Vourinos Complex. In the majority of
cases they are well foliated. Foliation planes are defined by
elongated and flattened (2 to 5 cm) clots of orthopyroxenes
(Harkins et al. 1980). Among the prevailing deformities two
penetrative deformation phases have been distinguished (Ayr-
ton 1968). Within the harzburgites irregular dunite pods and
lenses with economical chromite accumulations are charac-
teristic. They are concentrated in the top kilometre of the man-
tle sequence (Augé & Johan 1988).

It is characteristic that the extent of the ore bodies bear no

relation to the size and shape of the enclosing dunite bodies
(l.c.). The contacts of the dunites and the surrounding
harzburgite tectonites are sharp. It should be mentioned that
their origin within the upper mantle harzburgites is still poorly
understood. The composition of the harzburgite tectonites as
well as dunites and chromitites should be considered as a
record of a fast-spreading (= large magma chamber) environ-
ment (Nicolas 1989).

The degree of serpentinization of the mantle harzburgite

tectonites is low (less than 15 per cent) except in the neigh-
bouring fractures in the vicinities of W–E trending faults
where the degree of serpentinization is higher. In general, ser-
pentinization of the southern block is more intensive (Ross et
al. l980).

— The next genetical unit of the Vourinos ophiolites are

crustal magmatites

 (= cumulate complex) which overlie the

harzburgite tectonites (Harkins et al. 1980).

The presence of such cumulates in numerous ophiolites have

been summed up by Jackson (l971). This complex (thickness
l500 m) has been originally characterized by Jackson et al.
(1975) as a cyclic unit with changeable composition in verti-
cal section. It is rich in coarse-grained (up to 2 cm) olivine at
the base and rich in feldspars at the top (Jackson et al. 1975).
Magmatic cumulates, in contrast to the metamorphic section of

Fig. 2. 

The general geology of the Vourinos Massif, Greece (Ras-

sios 1983).

Fig. 3.

 Generalized stratigraphic column of the Vourinos Ophiolite

Complex, Greece. Kls — Cenomanian limestone; cls — Calpi-
onellid limestone; c — chert; pb — pillow basalt; sd — sheeted
dikes; — plagiogranite; ndi — non cumulate diorite; cdi — cu-
mulate diorite; ug — uralitized gabbronorite; cg — cumulate gab-
bronorite; g — unaltered gabbronorite; cr — cumulate rocks; umf

 — ultramafic cumulates; cu — cyclic unit; cdb — cumulate dun-

ite body; db — dunite body; dt — dunite tectonite; ht  —
harzburgite tectonite; — massive serpentinite; Jrc — Jurassic
carbonates; mr — magmatic rocks (Rassios 1981).

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14                                                                                SAVVIDIS  and  HOVORKA

the complex, preserve their initial mineralogical layering (24
cyclic units of the Stillwater or Bushveld type have been dis-
tinguished by Jackson et al. 1975). The cyclic units now stand
nearly vertically. Structures typical for sedimentary sequenc-
es have been reported (Harkins et al. 1980). Later studies (Ras-
sios et al. 1983b) brought evidence that some features of cy-
clic development of magmatites exist, but this feature is not
universal for the whole complex.

Within the lowermost section of cumulates Jackson et al.

(1975), described cyclic units of dunites (with various textural
types of chromite mineralization, not of economical concen-
trations), wehrlites and clinopyroxenites. In a stratigraphically
upward direction this portion changes to the upper cumulates
which consist of Ol-gabbros, gabbros followed by notitic gabbros
passing to leucodiorites (= small bodies of ”plagiogranites”).

The upper cumulate complex is locally intruded by dolerite

sills and dykes. Dyke swarm occurs in diorites. On top of the
magmatic sequence massive basaltic lava flows are known to
occur, through only within a small area.

Metallogenic aspects

— Vourinos is well known for its chromite ores. Xeroliva-

do and its neighbouring mines were the most productive on
the European continent. Chromitites are known to occur in
both main lithological units, though those of economic impor-
tance are found in dunites within harzburgite tectonites (Rob-
erts et al. l988; Rassios & Kostopoulos l987).

Chromite ores are confined to tabular zones up to 2 km

thick that occur subparallel to the basal plane of the complex.
It could be supposed that the chromite-rich horizons represent
the remnant of deformed dunite-chromite enriched zones of
the mantle.
Taking into account chromite occurrences in both, the main
lithological units, according to Zachos (1954) classification,
the following textural types of chromite ores could be distin-
guished: a — disseminated, b — schlieren, c — massive, d —
nodular (ooidal, leopard-type known from cumulates only),
e — layered (Pl. II). In the majority of cases different types of
ores coexist in one occurrence. Consequently it is classified
according to the prevailing textural type of ore. On the basis
of the nodular type occurring in the basal part of cumulates
(for example at Tsouka) it seems that this is the prevailing
type among cumulate dunites. On the other hand schlieren
type ores form the bulk of the economic deposits of Vourinos.
Modal chromite in this type varies between l5 to 44 per cent
(Rassios 1986).

— Systematic studies performed during the last decade en-

able us to list Pt-group minerals (PGM) determined within the
Vourinos Complex as follows (Augé & Johan l988): laurite,
alloys: iridosmine, rutheniridosmine, osmiridium and sulphars-
enides: osarsite and irarsite. PGM were determined both in
chromitites and in disseminated chromites. They are present as
minute grains (1 to 10 µm) and are generaly euhedral.

— The asbestos mine at Zindani is located within the anti-

gotite serpentinite body. It belongs most probably to the Pelag-
onian massif located east of Vourinos. Deposits of slip-fiber as-
bestos of complicated mineralogy (Hovorka et al. 1997), which
locally reache quality of textile asbestos are exploited.

— A crust of lateritic weathering is preserved in only a few

places on the Vourinos ophiolites (Microcastro-Siatista area).
Taking into account the eroded section of the ophiolite, preserva-
tion of laterites (were elevated nickel concentrations can be ex-
pected) should occur in ancient topographical depresions.

Plate I:

 a — Deformation bands in olivine of dunite (located within

the upper mantle harzburgite tectonite). Enl. 


27, crossed nicols. b —

Harzburgite tectonite with core-mantle structure of pyroxenes; exso-
lution of Cpx of Opx. Enl. 


27, crossed nicols. c — Intensively

crushed olivine in harzburgite tectonite with slight serpentinization on
cracks. Enl. 


45, crossed nicols. d — Harzburgite tectonite (catacla-

site). Enl. 


45, crossed nicols. e — Total serpentinization of olivines

in harzburgite tectonite — mesh texture. Enl. 


45, crossed nicols.  f —

 Antigorite serpentinite (Kamvounia-Zindani) with random orientation
of antigorite blades. Enl. 


43, crossed nicols.

Fig. 4.

 Model for genesis of the Vourinos ophiolites. Hypothetical

NNE–SSW cross-section through the ridge and lithosphere of
which the Vourinos Complex is a fragment. Olivine crystals at a
depth of about 60 km within the diapir are oriented with [100] axes
vertical. At about 30 km flow lines rotate to the horizontal and
kinking of olivine occurs; subsequently, mylonites develop. Stip-
pled areas represent sediments; short random lines represent crys-
talline crust; horizontal lines represent a small magma chamber
(Ross et al. 1980).

Genetic aspects

The dunite bodies could have originated in one of the fol-

lowing ways: as depleted solid residues of a partial melting of
a peridotitic precursor, or, as magmatic segregations. Follow-
ing Harkins et al. (1980) the problematics of dunite bodies can
be summed up as follows: 1 — they are produced by a process
that forms consistently sharp contacts, 2 — they are formed both
before and after deformation, 3 — the composition of chrome
spinels included in them is the same in all bodies and the same
as that of the lower cumulate chromites, 4 — morphologies of
chrome spinels in all their occurrences are similar.


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16                                                                                SAVVIDIS  and  HOVORKA

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Jackson et al. (1975) located the formation of the Vourinos

stratiform (cumulate) complex near the actively spreading mid-
oceanic ridge (Fig. 4). The composition of olivine and py-
roxenes in the Vourinos indicate that they were produced from
a mantle source with an 100


Mg/Mg + Fe of about 89. After

melting of the protolith harzburgite residuum, Ol and Px in the
range Mg91–93 would have originated. Cumulus olivines have
more-or-less the same composition (Jackson et al. l975).

Following the results of Jackson et al. (1975) the Vourinos

ophiolites can be characterized by:
i) the presence of well developed cyclic magmatites (cumu-
lates) in the upper part of the section,
ii) strong lineate lamination of its rocks,
iii) by sharp, undisturbed boundaries between magmatite cu-
mulates and harzburgite tectonites.

Widespread postcumulus overgrowth within cyclic mag-

matic unit (cumulates) indicates that the Vourinos Complex
was formed on a relatively slowly spreading ridge (Jackson et
al. 1975). This general idea was later corrected with the view
that the Vourinos Complex is a remnant of a mantle diapir
with an overlying magma chamber (Ross et al. 1980).

The degree of serpentinization of the harzburgite tectonites

as well as the lower part of the cumulates is generally low. It
is more intensive in the cracks and shear zones (Ross et al.
1980). Intensive serpentinization is characteristic of the ”bas-
al serpentinites”. Applying generally accepted ideas, the ser-
pentinization of the Vourinos could be attributed to  the low-
temperature hydration processes which it underwent within the
upper crust P-T regime during final emplacement of the complex.

Open problems

— Following the paper by Moores (1969), later authors have

described the presence of metamorphic rocks on the south east-
ern rim of the complex.

These metasmorphic rocks can be seen outcropping on the

slopes of the Aliakmon River in the vicinity of Zaborda mon-
astery. Metamorphics of the amphibolite facies occur on the
tectonic boundary of the Vourinos Complex and the rock se-
quences of the Pelagonian massif. The presence of garnet
amphibolites (Moores l969) — only a few metres thick — in-
dicates processes of high-grade metamorphic recrystallization
during the emplacement of the complex. Such metamorphic
recrystallization should be characterized as ”deep blastomy-
lonites”. The possibility of the retrogressive origin of garnet
amphibolites (original eclogites) should be taken into consid-

— Among the not yet definitely solved problems that

should be mentioned here is that of the metamorphic gap be-
tween the amphibolite facies rocks on one side and the lizard-
ite-chrysotile serpentinites (= basal serpentinites) on the other
one. Metamorphically contrasted lithologies occur on both
sides of the emplacement (tectonic) zone only few meters
thick. This metamorphic gap should serve for future consider-
ations and studies.

— Within the harzburgite tectonites and the ultramafic (low-

ermost) members of the crustal cumulates serpentinites of the
Vourinos Complex a remarcable serpentinite horizon which is
located just above the basal plane (= basal serpentinites) has
been reported by Moores (l969), Coleman (l97l) and Ross et al.
(l980). Information on the presence of mostly lizardite-cli-
nochrysotile in Vourinos has been reported by Coleman (l97l).
Missing chrysotile in the form of cross-fiber chrysotile (name-
ly in tectonically undeformed ultramafic cumulates) limits the
P-T conditions of serpentinization processes. No further infor-
mation regarding other problems is available at present.


Augé T., 1985: Platinum-group-mineral inclusions in ophiolitic

chromitite from the Vourinos complex, Greece. Canad. Miner-

, 23, 163–171.

Augé T. & Johan Z., l988: Comparative study of chromite deposits

from Trodos, Vourinos, North Oman and New Caledonia ophi-
olites. In: J. Boissonnas & P. Omenetto (Eds.): Mineral Deposits
within the European Community. Springer Verlag,


Heidelberg, 267–288.

Ayrton S., l968: Structures isoclinales dans les péridotites du Mont Vouri-

nos (Macédoine grecque), un example de déformation des roches ul-
trabasiques. Schweiz. Mineral. Petrogr. Mitt., 48, 733–746.

Beccaluva L., Ohnenstetter D., Ohnenstetter M. & Paupy A., l984:

Two magmatic series with island arc affinities within the Vouri-
nos ophiolite. Contr. Mineral. Petrology, 85, 253–271.

Brunn J.H., l956: Contribution a l’étude géologique du Pinde septen-

trional et d’une partie de la Macédoine occidental. Ann. Géol.
 Pays Hellén.,

 7, 1–358.

Coleman R.G., l971: Petrologic and geophysical nature of serpen-

tinites. Geol. Soc. Amer. Bull., 82, 897–918.

Harkins M.E., Green H.W. & Moores E.M., 1980: Multiple intrusive

events documented from the Vourinos ophiolite complex,
northern Greece. Amer. J. Sci., 280-A, 284–295.

Hovorka D., Savvidis S., Stankovič J., Šamajová E. & Turanová L.,

1997: Serpentines of the ophiolite complexes Vourinos and
Kamvounia Mts. (Northern Greece). Geol. Carpathica, 48, 19–26.

Jackson E.D., l97l: Origin of ultramafic rocks by cumulus process-

es. Fortschr. d. Mineral. (Stuttgart), 48, 128–174.

Jackson, E.D., Green H.W. & Moores E.M., 1975: The Vourinos

Ophiolite, Greece: Cyclic units of lineated cumulus overlying
harzburgite tectonite. Geol. Soc. Amer. Bull., 86, 390–398.

Mavridis A., Skourtsis-Coroneou V. & Tsaila-Monopolis St., 1979:

Contribution to the geology of Subpelagonian Zone (Vourinos
area, West Macedonia). In: VI Coll. Geol. Aegean Region. In-
stitute of Geological and Mining Resarch,

 Athens, 175–195.

Moores E.M., l969: Petrology and structure of the Vourinos ophi-

olitic complex of northern Greece. Geol. Soc. Amer., Spec.

, 118, 1–74.

Moores E.M. & Vine F., 1971: The Troodos Massif, Cyprus and oth-

er ophiolites as oceanic crust: evaluation and implications. Phil.
Trans. Roy. Soc. Lond.,

 A, 268, 443–466.

Mountrakis D., 1983: Geology of Greece. Univ. Studia Press, Thes-

saloniki, 1–207 (in Greek).

Nicolas A., l989: Structures of ophiolites and dynamics of oceanic

lithosphere. Kluwer Acad. Publ., Dordrecht, 1–367.

Noiret et al., l98l: Is the Vourinos complex an island arc ophiolith?

Earth Planet. Sci. Lett

., 56, 375–386.

Pichon S.F., l976: Conditions de gisement des ophiolithes sur la

bordure occidentalle du Vermion zone pelagoniane, Grece.
These schéme cycle, Univ. Paris Sud., 1–l97.

Pichon S.F. & Lys M., l976: Sur l’ existence d’une série du Jurassic

supérieur a Crétacé inférieur, surmontant des ophiolites dans

Plate II:

 Main textural types of chromite ores of the Vourinos

Complex: a — nodular/ooidal, leopard-type; — layered; c —
disseminated; d — schlieren; e — nodular-disseminated; f — dis-


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les collines de Krapa (Massif du Vourinos, Grece). C. R. Acad.

 Paris, 282, 523–526.

Rassios-Ewing A., 1981: Geology and evolution of the magmatic

rocks of the Vourinos ophiolite, Northern Greece. Unpubl. Ph.
D. Theses. Univ. of California

, Davis, 1–594.

Rassios A., Beccaluva L., Bortolotti V., Mavrides A. & Moores E.,

l983a: Vourinos ophiolite complex. Field quidebook for workshop
on Vourinos-Guergueli ophiolites. IGCP 197, Ofioliti, 8, 275–292.

Rassos A.E., Moores E.M. & Green H.W., l983b: Magmatic structure

and stratigraphy of the Vourinos cumulate zone, Northern
Greece. Ofioliti, 8, 377–410.

Rassios A. & Kostopoulos D., 1987: The geochemistry of dunite and

its relation to the position of chromitites in the Vourinos Ophi-
olite Complex, Greece. Ophiolites: Oceanic crustal analogues.
Proc. of the Symp. Trodos

, Zipern 1987, 593–603.

Rassios A., Grives E., Vacandios I. & Konstantopoulou G., l995:

Structural-geochemical-metallogenetic unification of the Pin-
dos and Vourinos ophiolites. Manuscript, I.G.M.E, Athens.

Rassios A., l986: Chromite mineralization and mining at Vourinos.

Tectonic controls on chrome ore localization in Vourinos Com-
plex, Greece. IGME Athens 1986, Appendix II, 128–142.

Rassios A.E., Morres E.M. & Green H.W., 1988: Magmatic structure

and stratigraphy of the Vourinos Ophiolite Complex, Northern
Greece. Ofioliti, 8, 3, 377–410.

Roberts S., Rassios A., Wright L., Vacandios I., Vrachatis G., Gri-

vas E., Nesbitt R.W., Neary C.R., Moat T. & Konstantopolou
L., l988: Structural controls on the location and form of the
Vourinos chromite deposits. In: Boissonnas J. & Omenetto P.
(Eds.):  Mineral Deposits within the European Community.
Springer Verlag,


Ross J.V., Mercier J.Cc., Ave Lallement. H.G., Carter N.L. &  Zim-

merman J., l980: The Vourinos ophiolite complex Greece: the
tectonite suite. Tectonophysics, 70, 63–83.

Smith A.G., l979: Othris, Pindos and Vourinos ophiolites and the

Pelagonian zone. In: 6th Colloquium on the Geology of the
Aegean Region (Vol. 3). IGME,

 Athens, Greece, 1369-1374.

Smith A.G. & Woodcock N.H., l976: Emplacement model for some

”Tethyan” ophiolites. Geology, 4, 653–656.

Spray J.G. & Rodick J.C., l980: Petrology and Ar





ogy of some Hellenic sub-ophiolite metamorphic rocks. Contr.
Mineral. Petrology

, 72, 43–55.

Zachos K., l954: Chromite deposits of Vourinos (Kozani) area.


Athens, Rep. No. 3, 1–82.

Zimmerman J., l972: Emplacement of the Vourinos ophiolitic com-

plex, northern Greece. In: Shagam R. et al. (Eds.): Studies in
Earth and Space Sciences — Hess volume. Geol. Soc. Amer.,

., 132, 225–239.