GeolCarp_Vol63_No2_97

www.geologicacarpathica.sk

GEOLOGICA CARPATHICA

, APRIL 2012, 63, 2, 97—106 doi: 10.2478/v10096-012-0008-4

Petrology of plagiogranite from Sjenica, Dinaridic Ophiolite

Belt (southwestern Serbia)

DRAGAN MILOVANOVIĆ

, DANICA SREĆKOVIĆ-BATOĆANIN

, MARIJA SAVIĆ

and DANA POPOVIC

University of Belgrade, Faculty of Mining and Geology, Department of Petrology and Geochemistry, Djusina 7, 11 000 Belgrade, Serbia;

danicabat@yahoo.com

Geological Institute of Serbia, Rovinjska 12, 11 000 Belgrade, Serbia

(Manuscript received September 7, 2010; accepted in revised form September 30, 2011)

Abstract: The Sjenica plagiogranite occurs in the southern part of the Dinaridic Ophiolite Belt, 5 km northwest of
Sjenica. The main minerals are albite with strongly altered biotite (replaced with chlorite), with occasional amphibole
(magnesio hornblende to tschermakite) and quartz. An enclave of fine-grained granitic rocks with garnet grains was
noted too. Secondary minerals are calcite and chlorite (daphnite). Major, trace and REE geochemistry coupled with
field observations support a model by which the Sjenica plagiogranite could be formed by fractional crystallization of
mantle origin mafic magma in a supra-subduction zone setting. Occurrences of calcite and chlorite nests in the Sjenica
plagiogranites revealed that these rocks underwent hydrothermal alteration due to intensive sea water circulation in a
sub-sea-floor environment.

Key words: Serbia, Dinaridic Ophiolite Belt, geochemistry, petrology, ophiolite, plagiogranite.

Introduction

Occurrences  of  plagiogranites  within  ophiolitic  complexes
are  of  particular  interest  because  of  their  extreme  composi-
tion  and  controversial  origin.  Ophiolitic  sequences  are  con-
sidered incomplete without plagiogranites.

In Serbia plagiogranites occur in the Dinaridic Ophiolite

Belt and in the Vardar Zone (Karamata & Krstić 1996). In the
Dinaridic Ophiolite Belt plagiogranites were noted at numer-
ous localities (Karamata 1958; Pamić & Olujić 1969; Pamić &
Tojerkauf 1970; Lugović et al. 1991; Majer & Garašić 2001),
while in the Vardar Zone they are less abundant (Milovanović
1980; Jović 1984). Both, the Dinaridic Ophiolite Belt and the
Vardar Zone, are parts of the Alpine-Mediterranean mountain
belt which belongs to a main suture zone between Eurasia and
Gondwanaland  after  their  collision  during  the  Late  Jurassic/
Early Cretaceous (Karamata 2006). These two differ in origin,
structure and age and can be traced continually nearly 700 km,
from  the  Southern  Alps  in  the  north  to  the  Hellenides  in  the
south.  Different  reconstructions  of  the  Mesozoic  ophiolite
evolution  in  the  Balkan  Peninsula  during  the  last  few  years
have aroused the questions about the existence of one or more
oceanic basins, their size, emplacement etc. One suggestion is
that  Tethys  ophiolites  were  developed  in  two  or  more  ocean
basins,  separated  by  rifted  micro-continents  (Pamić  1999;
Karamata  et  al.  2000;  Pamić  et  al.  2002;  Robertson  2002;
Stampfli & Borel 2002; Karamata 2004). During the Meso-
zoic, the Drina-Ivanjica-Pelagonide micro-continent separated
the Vardar Ocean in the east from the Dinaridic Ocean in the
west (Robertson & Karamata 1994). An alternative suggestion
is  that  Tethys  ophiolites  were  generated  from  a  single  ocean
basin  (e.g.  Dercourt  et  al.  1986,  1993;  Dal  Piaz  et  al.  1995;
Bortolotti et al. 2004).

The aim of this paper is to define petrographic and

geochemical features of the Sjenica plagiogranites which oc-
cur in the southern part of the Dinaridic Ophiolite Belt. This
part of the Eastern Mediterranean region has been investigated
by numerous workers. The most important studies are those
made by Karamata who has studied the Sjenica plagio-
granites and initiated a new approach to interpretation of
Mesozoic evolution in this region (1958, 2004).

Geological setting

The Sjenica plagiogranite occurs in the southern part of

the  Dinaridic  Ophiolite  Belt,  which  represents  remnants  of
the  Tethys  and  its  marginal  seas.  The  Sjenica  plagiogranite
occurs 5 km northwest of Sjenica (Coordinates: E 7146381,
N 4793606;  Fig. 1).  The  largest  area  is  covered  by  ophiolite
mélange  (J

2,3

) composed of chert, sandstone, claystone, lime-

stone, diabase, gabbro, serpentinite and plagiogranite blocks
(lenses) bonded with the sandy-silty matrix. Triassic rocks com-
prise widespread Middle Triassic limestone and dolomites with
chert concretions and Upper Triassic banked to massive, highly
karstified dolomitic limestone and dolomites, reaching in thick-
ness up to 300 m. Lower Jurassic, Liassic limestone (J

) is light

reddish,  oolitic  in  places.  The  youngest  unit  in  this  area
is Miocene in age and corresponds to freshwater sediments with
lignite layers and less abundant marly and dolomitic limestone
(Fig. 2).  Plagiogranites  occur  as  lenses,  about  50 m  in  length
and  20 m  in  thickness,  enclosed  in  the  ophiolitic  mélange,
with  irregular  and  jagged  contacts.  Field  relations  between
plagiogranites and surrounding rocks could not be established
due  to  intensive  faulting.  The  present  variably  dismembered
state is related to obduction and post-obduction tectonics.

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Methods and techniques

On the basis of careful petrographic study of 30 samples, a

representative suite of 5 samples was selected for geochemical
analysis. The major element oxide, trace and REE element

contents of these rock samples were analy-
sed  at  the  ACME  analytical  laboratory  in
Vancouver  (Canada).  The  major  and  trace
elements  were  determined  from  fused
LiBO

discs by ICP-OES and ICP-MS, re-

spectively,  using  5 g  of  sample  powder.
Rare  Earth  elements  were  analysed  by  in-
ductively coupled plasma-mass spectrome-
try (ICP-MS). The composition of minerals
in selected samples was determined using a
CAMECA  SX  100  electron  microprobe  at
the  Department  of  Mineralogy  and  Petro-
graphy, University of Hamburg, Germany.
Operating  conditions  were  20 kV  acceler-
ating voltage and 20 nA beam current with
20 s  and  2 s  counts  for  peak  and  back-
ground respectively.

Petrography and mineral chemistry

The Sjenica plagiogranite is holocrystal-

line,  medium-  to  coarse-grained  (average
grain size 2 mm), homogeneous and unfoli-
ated (Fig. 3). The overall texture is hypidio-
morphic  granular.  These  rocks  show  slight
variations  in  the  proportions  of  mafic  and
felsic  minerals  across  the  outcrop.  Plagio-
granites are mainly composed of plagioclase
(albite)  and  quartz  (Fig. 4).  Vermicular
quartz-plagioclase  intergrowths  that  were
interpreted  as  a  primary  magmatic  feature
by  Coleman  &  Donato  (1979),  have  been
observed occasionally. Quartz comprises up
to  30 %  of  the  mode.  In  samples  with  am-
phibole  the  quantity  of  quartz  decreases  to
about 20—25 %.

Albite is present as euhedral, twinned

crystals,  up  to  5 mm  in  size,  with  minor
sericitization.  Plagiogranites  contain  40  to
50 %  modal  albite.  Twelve  plagioclase
grains  were  analysed.  According  to  the  ob-
tained data, presented on Table 1 they corre-
spond  to  almost  pure  albite  ranging  in
composition between Ab (92.1—98.7 %).

Mafic minerals are chlorite, strongly al-

tered  biotite  (?)  and  occasional  amphibole.
Chlorite occurs in veins, as irregular patches,
interstitial accumulations (nests between al-
bite and quartz grains) or as pseudomorphs
after  primary  biotite.  Chlorite  is  present  in
abundances from 5 % to 10 %. Microprobe
analyses  of  chlorite  were  performed  on
twelve  chlorite  grains  (Table 2).  The  ob-

tained X

values (Fe/Fe + Mg) range from 0.807 to 0.848.

Chlorites are dominantly daphnite (Holland & Powell 1998).

Amphiboles occur locally in the eastern part of the out-

crop. They are randomly oriented, typically exhibiting pris-
matic and acicular shapes. This mineral is partially altered

Fig. 1. The terranes in the central part of the Balkan Peninsula along with the position
of the Sjenica plagiogranite: ESCB – The composite terrane of the Carpatho-Bal-
kanides; SMCT – The Serbian-Macedonian Composite Terrane; VZCT – The Vard-
ar Zone Composite Terrane; KB – The Kopaonik Block; JBT – Jadar Block
Terrane; DIT – The Drina-Ivanjica Terrane; DOB – The Dinaridic Ophiolite Belt;
EBDT – The East Bosnian-Durmitor Terrane; CBMT – The Central Bosnia Mts Ter-
rane; DHCT – The Dalmatian-Herzegovinian Composite Terrane (after Karamata 2004).

Fig. 2. Geological map of the Sjenica area with the occurrence of the plagiogranite
(black arrow). Basic Geological Map, Sheet Bijelo Polje, 1 : 100,000 (Živaljević et al.
1982). Legend: T

– Middle Triassic limestone with cherts; T

– Upper Triassic lime-

stone; J

– Liassic reddish limestone; J

2,3

– Ophiolitic mélange;

– Basaltic pillow

lavas; Se – Serpentinite; M

– Miocene clastic sediments;

– Plagiogranite (on the

Basic Geological Map signed as granodiorite and quartzmonzonite).

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GEOLOGICA CARPATHICA, 2012, 63, 2, 97—106

Table 1: Chemical composition of albite.

Table 2: Chemical composition of chlorite.

Table 3: Chemical composition of amphibole ( – core of grains).

Sample

SiO

66.95 66.83 66.96 66.81 67.32 67.48 66.42 67.21 66.78 66.86 66.03 66.32

20.61 20.97 20.42 20.92 20.77 19.97 21.09 20.32 20.87 20.91 22.11 20.78

CaO

0.35 0.11 0.12 0.41 0.12 0.16 0.21 0.21 0.35 0.43 0.16 0.26

10.95 10.94 10.99 10.87 11.22 11.35 10.87 11.23 10.99 10.95 10.31 10.98

0.00 0.64 0.59 0.61 0.15 0.22 0.94 0.21 0.52 0.61 1.21 0.73

Total

98.86 99.49 99.08 99.62 99.58 99.18 99.53 99.18 99.51 99.76 99.82 99.07

Calculated on 32 O

11.81 11.76 11.83 11.75 11.81 11.89 11.71 11.84 11.75 11.74 11.60 11.74

4.28 4.34 4.25 4.33 4.29 4.14 4.38 4.22 4.33 4.33 4.58 4.33

0.07 0.02 0.02 0.08 0.02 0.03 0.04 0.04 0.07 0.08 0.03 0.05

3.75 3.73 3.76 3.71 3.81 3.88 3.72 3.84 3.75 3.73 3.51 3.77

0.00 0.14 0.13 0.14 0.03 0.05 0.21 0.05 0.12 0.14 0.27 0.17

1.8 0.6 0.5 2.0 0.6 0.8 1.0 1.0 1.8 2.0 0.8 1.2

98.2 95.9 96.2 94.4 98.7 98.0 93.7 97.7 95.2 94.4 92.1 94.5

0.0 3.5 3.3 3.6 0.7 1.2 5.3 1.3 3.0 3.6 7.1 4.3

Sample

SiO

23.58 23.33 25.31 25.24 24.63 23.43 23.54 23.26 23.29 24.51 25.14 24.36

Al2O

20.29 20.91 19.09 19.98 19.20 19.86 20.02 20.83 20.31 19.70 18.98 19.08

FeO

tot

37.06 38.32 37.22 37.40 37.98 38.74 38.88 38.09 38.55 38.38 37.79 39.26

MnO

1.03

1.05

0.82

0.86

0.95

1.04

0.97

1.09

1.07

0.89

0.85

1.05

MgO

4.98

3.92

4.62

4.43

4.18

4.16

4.18

4.03

4.33

4.48

3.95

Total

86.94

87.53

87.06

88.10

87.19

87.25

87.57

87.45

87.25

87.81

87.24

87.70

Calculated on 28 O

5.39

5.34

5.76

5.67

5.61

5.39

5.40

5.32

5.36

5.57

5.71

5.59

5.42

5.63

5.11

5.28

5.15

5.38

5.41

5.61

5.50

5.27

5.08

5.15

7.08

7.33

7.08

7.02

7.23

7.46

7.29

7.42

7.30

7.18

7.53

0.20

0.16

0.18

0.20

0.19

0.21

0.17

0.16

0.20

1.70

1.34

1.57

1.55

1.50

1.43

1.42

1.43

1.38

1.47

1.52

1.35

Sample

SiO

49.72 50.04 41.93 42.15 42.63 42.01 41.83 48.96 49.52 48.46

TiO

0.03 0.87 3.63 3.46 3.26 3.31 3.40 0.97 0.88 1.06

4.57 4.14 12.06 12.03 11.34 11.75 11.92 4.94 4.16 5.02

FeO

tot

18.69 17.63 13.63 13.51 13.41 13.71 13.46 17.72 17.45 17.80

0.03 0.07 0.03 0.02 0.03 0.06 0.05 0.07 0.09 0.14

MnO

0.64 0.27 0.23 0.00 0.23 0.26 0.00 0.23 0.27 0.31

MgO

11.29 13.27 13.27 13.29 13.31 13.27 13.29 12.88 13.16 12.69

CaO

11.30 10.01 10.89 10.90 10.89 10.90 10.91 10.16 9.74 10.11

0.61 0.98 2.49 2.49 2.38 2.46 2.51 1.10 0.96 1.13

0.20 0.20 0.11 0.13 0.10 0.11 0.11 0.29 0.19 0.28

Total

97.08

97.48

98.27

97.98

97.58

97.84

97.48

97.32

96.42

97.00

Calculated on 23 O (13-CNK)

7.332

7.198

6.039

6.085

6.177

6.078

6.074

7.090

7.185

7.051

0.003

0.094

0.393

0.376

0.355

0.360

0.371

0.106

0.096

0.116

0.794

0.701

2.045

2.046

1.936

2.002

2.038

0.842

0.711

0.860

0.003

0.008

0.003

0.002

0.003

0.007

0.006

0.008

0.010

0.016

0.748

1.312

1.010

0.937

0.927

1.025

0.945

1.244

1.382

1.267

1.557

0.809

0.631

0.694

0.698

0.634

0.690

0.902

0.735

0.899

0.080

0.033

0.028

0.000

0.028

0.032

0.000

0.028

0.033

0.038

2.482

2.845

2.849

2.860

2.875

2.862

2.877

2.780

2.847

2.753

1.785

1.543

1.680

1.686

1.691

1.690

1.697

1.576

1.514

1.576

0.174

0.273

0.696

0.697

0.668

0.690

0.707

0.309

0.270

0.319

0.038

0.037

0.020

0.024

0.018

0.020

0.054

0.035

0.052

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Fig. 6. Enclave of fine-grained plagiogranite with garnet porphyroblasts (?), black arrow. Microphotograph is N II.

Table 4: Chemical compositions of garnets.

Sample

SiO

36.36 36.38 36.46 36.11 36.79 36.50

TiO

0.28 0.29 0.25 0.27 0.25 0.25

21.28 20.96 21.05 20.83 20.79 20.86

FeO

tot

34.48 34.20 34.80 34.37 34.13 34.25

0.05 0.06 0.08 0.00 0.06 0.07

MnO

2.16 2.35 2.15 2.37 2.36 2.00

MgO

3.71 3.78 3.76 3.46 3.46 3.75

CaO

1.69 1.83 1.71 1.93 1.78 1.71

Total

100.01

99.85

100.21

99.34

99.62

99.39

Calculated on 12 O

2.925

2.925 2.921 2.923 2.969 2.947

0.017

0.075

0.015 0.016 0.015 0.015

1.997

1.984

1.986 1.986 1.977 1.984

0.003

0.004

0.005 0.000 0.004 0.004

2.320

2.299

2.331 2.327 2.304 2.313

0.147

0.160

0.146 0.163 0.161 0.137

0.445

0.453

0.449 0.418 0.416 0.451

0.146

0.158

0.147 0.167 0.154 0.148

Almandine 68.500 67.183

68.208 68.174 67.780 68.216

Andradite

6.016

6.469

5.965 7.128 2.961 5.218

Grossulare

0.000

0.000 0.000 3.566 0.880

Pyrope

18.997 19.291 19.248 17.779 18.335 19.491

Spessartine

6.284

6.814

6.253 6.919 7.106 5.906

Uvarovite

0.204

0.244

0.326 0.000 0.253 0.289

The garnet is almandine rich, but it must be noted that the

high amount of Fe

probably implies subsequent alteration

processes (Table 4). Almandine component ranges from 67.2
to 68.5 %, pyrope from 17.8 to 19.5 %. Spessartine and an-
dradite contents are about 6 %, whereas amounts of uvaro-
vite and grossular components are insignificant. No
compositional zoning was detected.

Classification and nomenclature

Coleman & Peterman (1975) proposed the term “oceanic

plagiogranite”  for  rocks  consisting  of  quartz  and  plagioclase
(An10—60),  typically  characterized  by  a  granophyric  inter-
growth  with  less  than  10 %  ferromagnesian  minerals.  This
term  encompasses  rocks  that  range  from  diorite  through
trondhjemite  to  albite  granite,  which  are  all  associated  with
ophiolites. On the basis of a wt. % K

O vs. SiO

discrimina-

tion diagram (Coleman & Peterman 1975; Coleman & Donato
1979; Maniar & Piccoli 1989), the Sjenica plagiogranites can
be  considered  as  oceanic  plagiogranites,  except  the  sample
with amphibole (Fig. 7). Plagiogranites from the Milatkoviće
village  near  Novi  Pazar  which  display  similar  geochemical
features  with  the  oceanic  plagiogranites  from  the  Troodos
ophiolite  massif  were  plotted  on  the  same  diagram
(Milovanović 1980). For the purpose of geochemical charac-
terization, CaO, Na

O and K

O have been plotted in the CNK

ternary diagram of Glikson (1979) and the CIPW-normative

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Fig. 9. Classification and nomenclature of the Sjenica plagiogranite
according to the normative An—Ab—Or diagram (after Barker 1979).

An,  Ab  and  Or  ternary  diagram  of  Barker  (1979).  In  both
diagrams,  samples  of  the  investigated  rocks  fall  in  the
trondhjemite field (Figs. 8 and 9). The exception is the sam-
ple  with  amphibole,  which  is  near  the  boundary  of
trondhjemite and tonalite fields on figure 8.

One rock (sample 5, with amphibole) within a representa-

tive suite of 5 selected samples has a bulk chemical composi-
tion  that  is  intermediate  between  the  plagiogranites  and  the
enclosing  gabbroic  rocks.  This  sample  has  a  relatively  high
MgO  content  (6.14 %)  and  a  lower  SiO

content (55.89 %)

with respect to the plagiogranites. The other four samples of
plagiogranites from Sjenica show low TiO

, K

O, P

, Rb

and Ba and high Na

O contents (Table 5).

Geochemistry

REE data (Table 5) and their distribution patterns show

that  the  plagiogranites  are  enriched  by  twenty  to  one  hun-
dred times compared with the relative average chondrite val-
ue  (Fig. 10).  They  all  show  similar  patterns  with  a  slight
LREE enrichment and a small negative Eu anomaly. The lat-
ter  indicates  plagioclase  involvement  during  either  a  frac-
tionation or melting process (Floyd et al. 1998).

On a multi-element spider diagram normalized to primi-

tive  mantle  the  Sjenica  plagiogranites  show  enrichments  of
Rb,  Ba,  K,  Th,  Sr,  depletions  of  Eu,  Ti,  P  and  Sr  and  flat
HREE  patterns  (Fig. 11).  When  taken  together  these  data
suggest that the plagiogranites may have been generated by
low-pressure  fractionation  in  which  plagioclase  and  pyro-
xene  were  important  differentiation  phases  and  garnet  and
hornblende were not involved (Drummond & Defant 1990).

Discussion

Usually suggested models for plagiogranite genesis in

ophiolite complexes are:

fractional crystallization of a parental MORB melt at shal-

low depths in oceanic crust. This model has been supported by
a number of authors on Alpine and Apennine ophiolites (e.g.
Coleman & Peterman 1975; Engel & Fisher 1975; Coleman
1977; Saunders et al. 1979; Dixon & Rutherford 1979;
Kontinen 1987; Borsi et al. 1996; Montanini et al. 2006);

partial melting of gabbroic rocks under hydrous condi-

tions in tectonically active areas of midocean ridge systems
(Gerlach et al. 1981; Pedersen & Malpas 1984; Koepke et al.
2004, 2007). The role of water-rich fluid, either of magmatic
origin (e.g. Maeda et al. 2002) or sea-water derived (e.g.
Gregory & Taylor 1981), is suggested by the presence of
amphibole in these leucocratic rocks;

liquid immiscibility (Dixon & Rutherford 1979);
special type of anatexis proceeding at the roof zone of

axial magma chambers under fast spreading ridges (e.g.
Michael & Schilling 1989).

Plagiogranites of Sjenica display similar values in the ele-

mental abundances with respect to ORG (ocean ridge granites;
Pearce et al. 1984). ORG-normalized patterns are character-

Fig. 8. Plot of the Sjenica plagiogranite ( – full symbols for pla-
giogranites with chlorite; – empty symbol for plagiogranite with
amphibole) and Milatkovice plagiogranite ( ) on K

O (%) vs. SiO

(%) binary diagram. Field boundaries are after Coleman &
Peterman (1975).

Fig. 7. Classification and nomenclature of the Sjenica plagiogranite
according to CNK diagram (Glikson et al. 1979).

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Table 5: Chemical composition of the Sjenica plagiogranites (1—4 –
plagiogranites with chlorite; plagiogranite with amphibole).

Fig. 10. REE patterns of plagiogranites (normalized values from
Sun & McDonough 1989).

Fig. 11. Primitive mantle normalized multielement spider diagram
of the Sjenica plagiogranite. Normalizing values from Sun &
McDonough (1989).

ized by high content of LILE elements (K

O, Rb, Ba and Th)

and  Ta  negative  anomalies  (Fig. 12).  Such  geochemical  fea-
tures  can  be  attributed  to  an  arc  or  suprasubduction  zone
ophiolitic plagiogranites or variable mobilizations of the LILE
elements  during  metamorphism,  crustal  involvement  and/or
hydrothermal alteration (ocean floor metamorphism).

On the N-MORB-normalized trace-element variation dia-

gram the Sjenica plagiogranites are characterized by some
large ion lithophile element (LILE) enrichments and relative
depletion in HFSE (Fig. 13).

Amphibole-bearing plagiogranites, which are present in

minor abundances, could form at fluid pressure of 200 MPa,
and at depths greater than 6 km (Dixon & Rutherford 1979).

The enclave with garnet appears to have originated by low

to moderate degree partial melting of hydrated basaltic/gab-

broic rocks in oceanic crust. The essential conditions for the
stability of garnet varies over a temperature range of 800—
1000 °C and within a pressure range of 0.9—1.4 GPa (Vielzeuf
& Schmidt 2001) which correspond to a depth < 30 km. The
garnet could not be regarded as a major residual phase as no
significant LREE/HREE fractionation was noted.

The major, trace and REE geochemistry and field relations

indicate that plagiogranites were formed through a complex
process of fractional crystallization of mantle origin mafic mag-
ma that derived under high degrees of partial melting in the
presence of water introduced by subduction (?). The chemistry
of the Sjenica plagiogranites cannot be explained without a sub-
duction processes (Moores et al. 1984). The enrichment of Rb,
Ba, Sr, Th and LREE values and the presence of Nb anomalies
are consistent with variable mobilization of the LILE elements

Sample

SiO

67.06 66.44 62.90 61.82 55.89

TiO

0.37 0.37 0.46 0.59 1.05

14.96 15.88 15.95 16.06 14.48

FeO

tot

5.17 5.75 6.13 8.71 8.76

MnO

0.13 0.16 0.17 0.23 0.20

MgO

0.53 0.71 0.73 1.23 6.14

CaO

1.52 1.38 3.08 2.02 3.84

6.41 6.15 6.46 5.73 5.61

0.61 0.93 0.76 0.84 0.15

0.16 0.15 0.20 0.25 0.11

LOI

2.38 2.09 3.26 2.71 3.31

Total

99.30 100.01 100.10 100.19 99.54

Trace elements (ppm)

124 115 121 106 103

146

187

184

231

0.6

0.3

0.4

8.8

4.7

326 340 380 398 191

1.3

0.8

171

291

115

120

125

209

115

124

REE elements (ppm)

25.5

15.2

61.8

34.1

7.5

4.1

33.7

17.7

8.9

4.5

2.2

1.3

10.1

5.3

2 2 2 1 1

11.7

2.4

1.2

7.9

3.8

1.2

0.6

7.4

3.5

1.1

0.53

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GEOLOGICA CARPATHICA, 2012, 63, 2, 97—106

in an arc or supra-subduction zone (SSZ). It is increasingly ac-
cepted  that  many  ophiolites  have  been  formed  by  spreading
above  subduction  zones,  the  so-called  supra-subduction  zone
ophiolites  (Pearce  et  al.  1984;  Shervais  2001).  Supra-subduc-
tion type ophiolites typically formed during short-lived periods
( < 5 Ma) of regional plate re-organization, in narrow rifted ba-
sins where melts were contaminated by partial melting of neigh-
bouring lower crust (Hall 1984; Dilek et al. 1999).

Occurrences of calcite and chlorite nests in the Sjenica

plagiogranites revealed that these rocks were affected by hy-
drothermal  alteration  due  to  intensive  sea  water  circulation
in  a  sub-sea-floor  environment  (Spooner  &  Fyfe  1973;
Lecuyer et al. 1990). Hydrothermal alteration in the oceanic
environment is known to often induce strong chemical mobi-
lization in ophiolites and ocean ridge rocks (Alt 1995, 1999).
The  high  Na

O and low K

O contents in plagiogranites are

due to exchange with sea water that gained access to the
magma chamber or to late magmatic vapour-phase transport
and removal of K

O (Coleman & Donato 1979; Sinton &

Byerly 1980). The availability of Na during these processes
was probably responsible for the enlargement of the stability
field of albite. Sea water infiltration into the lower crust oc-
curred along listric shear zones under low fluid/rock ratios
during the initial stages of deformation and metamorphism.
These relations clearly show that successive episodes of hy-
drothermal alteration of fossil oceanic crust in the Dinaridic
Ophiolite Belt were entirely intra-oceanic in origin.

Conclusion

The Sjenica plagiogranites correspond to remnants of an

oceanic basement evolved in the Dinaridic Ophiolite Belt, and
so in an intra-oceanic environment. The absence of LT/HP
metamorphism suggests that ocean basins in which the
Dinaridic ophiolites have been formed were mainly bordered
by passive margins.

The Sjenica plagiogranites, a part of the East Mediterra-

nean  ophiolites  are  fragments  of  the  oceanic  lithosphere
probably  related  to  a  process  of  fractional  crystallization  of
mantle  origin  mafic  magma  in  the  so-called  supra-subduc-
tion  zone.  The  SSZ  type  ORG  affinity  of  the  Sjenica  pla-
giogranite is substantiated by a low content of HFSE relative
to  high  abundance  of  LILE.  The  mineral  composition  and
chemistry of plagiogranites were additionally changed due to
interaction  with  sea  water  during  sub-sea-floor  metamor-
phism.  However,  a  complete  understanding  of  these  ophio-
lite emplacements remains elusive including the occurrence
of garnet that requires further investigation.

Acknowledgments: We are grateful to colleagues at the De-
partment  of  Mineralogy  and  Petrography,  University  of
Hamburg for enabling chemical analyses of minerals for this
manuscript.  We  thank  reviewers  for  their  very  helpful  and
much  appreciated  comments  and  suggestions  for  improve-
ment of the manuscript. This research has been supported by
the Serbian Ministry of Science, Project No. 176019.

References

Alt J.C. 1995: Subseafloor processes in mid-ocean ridge hydrother-

mal  systems.  In:  Humphris  S.E.,  Zierenberg  R.A.,  Mullineaux
L.S.  &  Thomson  R.E.  (Eds.):  Seafloor  hydrothermal  systems.
Physical,  chemical,  biological,  and  geological  interactions.
Amer. Geophys. Union, Geophys. Monograph., Washington, DC
91, 85—114.

Alt J.C. 1999: Very low grade hydrothermal metamorphism of ba-

sic igneous rocks. In: Frey M. & Robinson D. (Eds.): Very low
grade metamorphism. Blackwell Scientific, 169—201.

Barker F. 1979: Trondhjemite: definition, environment and hypo-

theses of origin. In: Barker F. (Ed.): Trondhjemites, dacites,
and related rocks. Elsevier, Amsterdam, 1—12.

Borsi L., Scharer U., Gaggero L. & Crispini L. 1996: Age, origin

and geodynamic significance of plagiogranites in lherzolites
and gabbros of the Piedmont-Ligurian ocean basin. Earth
Planet. Sci. Lett. 140, 227—241.

Fig. 12. Spider diagram for the Sjenica plagiogranites. Normalizing
values from Pearce et al. (1984).

Fig. 13. N-MORB-normalized incompatible element diagram for
the Sjenica Plagiogranites. Normalized values from Sun &
McDonough (1989).

105

PETROLOGY OF PLAGIOGRANITE FROM THE DINARIDIC OPHIOLITE BELT (SW SERBIA)

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2012, 63, 2, 97—106

Bortolotti V., Chiari M. & Marcucci M.M. 2004: Comparison among

the Albanian and Greek ophiolites: In search of constraints for
the evolution of the Mesozoic Tethys Ocean. Ofioliti 29, 19—35.

Coleman R. 1977: Ophiolites-ancient oceanic lithosphere? Springer

Verlag, New York, 1—229.

Coleman R.G. & Donato M.M. 1979: Oceanic plagiogranite revisit-

ed. In: Barker F. (Ed.): Trondhjemites, dacites, and related
rocks. Elsevier, Amsterdam, 297—300.

Coleman R.G. & Peterman Z.E. 1975: Oceanic plagiogranite. J.

Geophys. Res. 80, 8, 1099—1108.

Dal Piaz G.V., Martin S., Villa I., Gosso G. & Marshalko R. 1995:

Late Jurassic blueschist facies pebbles from the Western Car-
pathian orogenic wedge and paleostructural implications for
Western Tethys evolution. Tectonics 14, 874—885.

Dercourt J., Zonenshain L.P., Ricou L.E., Kazmin V.G., Le Pichon

X., Knipper A.L., Grandjacquet C., Sbortshhikov I.M., Gey-
ssant J., Lepvrier C., Perchersky D.H., Boulin J., Sibuet J.-C.,
Savostin L.A., Sorokhtin O., Westphal M., Bazhrnov M.L.,
Lauer J.-P. & Biju-Duval B. 1986: Geological evolution of the
Tethys belt from the Atlantic to the Pamirs since the Lias. Tec-
tonophysics 123, 241—315.

Dercourt J., Ricou L.E. & Vrielynck B. (Eds.) 1993: Atlas Tethys

Paleoenvironmental Maps. Beicip—Franlab.

Dilek Y., Thy P., Hacker B. & Grundvig S. 1999: Structure and pe-

trology of Tauride ophiolites and mafic dyke intrusions (Tur-
key), implications for the Neotethyan ocean. Bull. Geol. Soc.
Amer. 111, 1192—1216.

Dixon S. & Rutherford M.J. 1979: Plagiogranite as late-stage im-

miscible liquids in ophiolite and mid-ocean ridge suites; an ex-
perimental study. Earth Planet. Sci. Lett. 45, 45—60.

Drummond M.S. & Defant M.J. 1990: A model for trondhjemite-to-

nalite-dacite genesis and crustal growth via slab melting: Archean
to modern comparisons. J. Geophys. Res. 95, 21503—21521.

Engel C.G. & Fisher R.L. 1975: Granitic to ultramafic rock com-

plexes of the Indian ocean ridge system, western Indian ocean.
Bull. Geol. Soc. Amer. 86, 1553—1578.

Floyd P.A., Yaliniz M.K. & Goncuoglu M.C. 1998: Geochemistry

and petrogenesis of intrusive and extrusive ophiolitic plagio-
granites, Central Anatolian crystalline complex, Turkey. Lithos
42, 225—241.

Gerlach D.C., Leeman W.P. & Ave Lallemant H.G. 1981: Petrology

and geochemistry of plagiogranite in the Canyon Mountain
Ophiolite, Oregon. Contr. Mineral. Petrology 77, 82—92.

Glikson A.Y. 1979: Early Precambrian tonalite-trondhjemite sialic

nuclei. Earth Sci. Rev. 15, 1—73.

Gregory R.T. & Taylor H.P. 1981: An oxygen isotope profile in a

section of Cretaceous oceanic crust, Semail Ophiolite, Oman:
evidence for

O buffering of the ocean by deep (>5 km) sea-

water hydrothermal circulation at Mid-Ocean ridges. J. Geo-
phys. Res. 86, 2737—2755.

Hall R. 1984: Ophiolites: fragments of ophiolitic lithosphere. In: Gass

I.G., Lippard S.J. & Shelton A.W. (Eds.): Ophiolites and oceanic
lithosphere. Geol. Soc. London, Spec. Publ. 13, 393—404.

Holland T.J.B. & Powell R. 1998: An internally-consistent thermo-

dynamic dataset for phases of petrological interest. J. Meta-
morph. Geol. 16, 309—344.

Jović V. 1984: Mafic and associated igneous rocks at the Jelica Mt.

Vesnik 17A, 5—43 (in Serbian).

Karamata S. 1958: Albit-granit von Sjenica (on German). Neu. Jb.

Mineral Mh., Stuttgart 6, 137—142.

Karamata S. 2004: Balkan Peninsula – a complex geological

framework. Proc. 5

Intern. Symposium on Eastern Mediterra-

nean Geology, Thessaloniki 1, 389—391.

Karamata S. 2006: The geological development of the Balkan Penin-

sula related to the approach, collision and compression of Gond-
wanan and Eurasian units. In: Robertson A.H.F. & Mountrakis

D. (Eds.): Tectonic development of the Eastern Mediterranean
Region. Geol. Soc. London, Spec. Publ. 260, 155—178.

Karamata S. & Krstić B. 1996: Terranes of Serbia and neighbouring

areas. In: Knežević V. & Krstić B. (Eds.): Terranes of Serbia.
Faculty of Mining and Geol., Belgrade, 25—40.

Karamata S., Dimitrijević M.D. & Dimitrijević M.N. 2000: A corre-

lation of ophiolitic belts and oceanic realms of the Vardar Zone
and the Dinarides. In: Karamata S. & Janković S. (Eds.): Pro-
ceedings of the International Symposium“Geology and Metal-
logeny of the Dinarides and the Vardar zone”. Acad. Sci. and
Arts of the Rep. of Srpska, Coll. and Monographs, Banja Luka—
Serb. Sarajevo 1, 191—194.

Koepke J., Feig T.S., Snow J. & Freise M. 2004: Petrogenesis of

oceanic plagiogranites by partial melting of gabbros: an exper-
imental study. Contr. Mineral. Petrology 146, 414—432.

Koepke J., Jasper Z., Berndt Z., Feig S.T. & Holtz F. 2007: The for-

mation of SiO

-rich melts within the deep oceanic crust by hy-

drous partial melting of gabbros. Contr. Mineral. Petrology
153, 67—84.

Kontinen A. 1987: An early Proterozoic ophiolite – the Jormua

mafic—ultramafic complex, northeastern Finland. Precambrian
Res. 35, 313—341.

Leake B.E., Wooley A.R., Arps C.E.S., Birch W.D., Gilbert M.C.,

Grice J.D., Hawthorne F.C., Kato A., Kisch H.J., Krivovichev
V.G.,  Linthout  K.,  Laird  J.,  Mandarino  J.,  Maresch  W.V.,
Nickel  E.H.,  Rock  N.M.S.,  Schumacher  J.C.,  Smith  D.C.,
Stephenson N.C.N., Ungaretti L., Whittaker E.J.W. & Youzhi
G. 1997: Nomenclature of amphiboles: report of the subcom-
mittee on Amphiboles of the International Mineralogical Asso-
ciation,  Commission  on  New  Minerals  and  Mineral  Names.
Canad. Mineralogist 35, 219—237.

Lecuyer C., Brouxel M. & Albartde F. 1990: Elemental fluxes hy-

drothermal alteration of the Trinity ophiolite (California,
U.S.A.) by seawater. Chem. Geol. 89, 87—115.

Lugović B., Altherr R., Raczek I., Hofmann A.W. & Majer V.

1991: Geochemistry of peridotites and mafic igneous rocks
from the Central Dinaridic Ophiolite Belt, Yugoslavia. Contr.
Mineral. Petrology 106, 201—216.

Maeda J., Naslund H.R., Jang YD., Kikawa E., Tajima T. & Black-

burn W.H. 2002: High-temperature fluid migration within oce-
anic  Layer 3  gabbros,  Hole 735B,  Southwest  Indian  Ridge:
implications for the magmatic-hydrothermal transition at slow-
spreading  mid-ocean  ridges.  In:  Natland  J.H.,  Dick  H.J.B.,
Miller  D.J.  &  Von  Herzen  R.P.  (Eds.):  Proceedings  of  the
Ocean Drilling Program, Scientific Results. ODP, College Sta-
tion, TX, 176, 1—60.

[Online] http://www.odp.tamu.edu/publications/176_SR/VOL-

UME/ CHAPTERS/SR 176_04. PDF>[Cited 23-08-2003]

Majer V. & Garašić V. 2001: Plagiogranites from the Dinarides and

the Vardar Zone. Rud.-Geol.-Naftni Zbornik, Zagreb 13, 1—7.

Maniar P.D. & Piccoli P.M. 1989: Tectonic discrimination of grani-

toids. Bull. Geol. Soc. Amer. 101, 635—643.

Michael P.J. & Schilling J.-G. 1989: Chlorine in mid-ocean ridge

magmas: evidence for assimilation of seawater-influenced
components. Geochim. Cosmochim. Acta 53, 3131—3143.

Milovanović D. 1980: Albite granite near Milatkoviće village (Novi

Pazar). Proc. Geoinst., Belgrade 14, XX, 175—182.

Montanini A., Travaglioli M., Serri G., Dostal J. & Ricci C.A.

2006: Petrology of gabbroic to plagiogranitic rocks from
southern Tuscany (Italy): evidence from magmatic differenti-
tation in an ophiolitic sequence. Ofioliti 31, 55—69.

Moores E.M., Robinson P.T., Malpas J. & Xenophontos C. 1984: A

model for the origin of the Troodos Massif, Cyprus and other
mideast ophiolites. Geology 12, 500—503.

Pamić J. 1999: Vardar zone of the Dinarides versus the Vardar

Ocean. Tübing. Geowiss. Arbeiten 52, 106—107.

106

MILOVANOVIĆ, SREĆKOVIĆ-BATOĆANIN, SAVIĆ and POPOVIC

GEOLOGICA CARPATHICA

GEOLOGICA CARPATHICA, 2012, 63, 2, 97—106

Pamić J. & Olujić J. 1969: Albite granite from Gostilje in the vicin-

ity of asbestos mine Bosansko Petrovo Selo. Geol. Glasnik, 13,
199—204 (in Croatian).

Pamić J. & Tojerkauf E. 1970: Granite occurences along the margin

of Borjane ultramafic massif. Geol. Glasnik 14, 149—153 (in
Croatian).

Pamić J., Tomljenović B. & Balen D. 2002: Geodynamic and petro-

genetic evolution of Alpine ophiolites from the central and
NW Dinarides: an overview. Lithos 65, 113—142.

Pearce J.A., Harris N.B.W. & Tindle A.G. 1984: Trace element dis-

crimination diagrams for the tectonic interpretation of granitic
rocks. J. Geol. 25, 956—83.

Pedersen R.B. & Malpas J. 1984: The origin of oceanic plagiogran-

ites from the Karmoy ophiolite, Western Norway. Contr. Min-
eral. Petrology 88, 36—52.

Robertson A.H.F. 2002: Overview of the genesis and emplacement

of Mesozoic ophiolites in the Eastern Mediterranean Tethyan
region. Lithos 65, 1—67.

Robertson A.H.F. & Karamata S. 1994: The role of subduction—ac-

cretion processes in the tectonic evolution of the Mesozoic
Tethys in Serbia. Tectonophysics 234, 73—94.

Saunders A.D., Tarney J., Stern C.R. & Dalziel I.W.D. 1979:

Geochemistry of Mesozoic marginal basin floor igneous rocks
from southern Chile. Bull. Geol. Soc. Amer. 90, 237—258.

Shervais W.J. 2001: Birth, death, and resurrection: The life cycle of

supra-subduction zone ophiolites. Geochemistry, Geophysics,
Geosystems. An electronic journal of the earth sciences.
Vol. 2. 1—45. Paper number 2000GC000080

Sinton J.M. & Byerly G.R. 1980: Silicic differentiates of abyssal

oceanic magmas: evidence for late-magmatic vapor transport
of potassium. Earth Planet. Sci. Lett. 47, 423—430.

Spooner E.T.C. & Fyfe W.S. 1973: Sub-seafloor metamorphism, heat

and mass transfer. Contr. Mineral. Petrology 42, 287—304.

Stampfli P.A. & Borel G.D. 2002: A plate tectonic model for the

Paleozoic and Mesozoic constrained by dynamic plate bound-
aries and restored synthetic oceanic isochrones. Earth Planet.
Sci. Lett. 196, 17—33.

Stern R.J. & Bloomer S.H. 1992: Subduction zone infancy: exam-

ples from the Eocene Izu-Bonin-Mariana and Jurassic Califor-
nia arcs. Geol. Soc. Amer. Bull. 104, 1621—1636.

Sun S.S. & Mc Donough W.F. 1989: Chemical and isotopic system-

atics  of  oceanic  basalts:  implications  for  mantle  composition
and  processes.  In:  Saunders  A.D.  &  Norry  M.J.  (Eds.):  Mag-
matism  in  ocean  basins.  Geol.  Soc.  London,  Spec.  Publ.  42,
313—345.

Vielzeuf D. & Schmidt M.W. 2001: Melting relations in hydrous

systems revisited: application to metapelites, metagreywackes
and metabasalts. Contr. Mineral. Petrology 141, 251—267.

Živaljević M., Mirković M. & Ćirić A. 1982: Basic geological map

1 : 100,000, sheet Bijelo Polje. Federal Geol. Inst., Belgrade.