Milovanović Dragan., Eric Suzana., Seke Lajos.

Milovanović Dragan., Eric Suzana., Seke Lajos.

Petrology and metamorphism of amphibolitesPetrology and metamorphism of amphiboliteswith corundum from Prijepolje , Dinaridic ophiolite with corundum from Prijepolje , Dinaridic ophiolite

Belt (Southwestern Serbia)Belt (Southwestern Serbia)

A L P S

A P E N I N E

S

Geographic position of Serbia on Balkan Peninsula

D I N A R I D E S

T H

K A R P A

A

B A L K

E S

O

N I

D

TISSIAThe Mesozoic ophiolites in Serbia

Amphibolites with corundum

The Mesozoic ophiolites in Serbia TISSIA

Amphibolites with corundum

Triassic limestone

Triassic limestone

Ophiolitic melange

Ophiolitic melange

Zlatibor peridotitesZlatibor peridotites

Pillow lavas

Triassic limestone

Amphibolites

with corundum

Peridotites

The field trip observations

Amphibilitewith corundum

Peridotites with Gr-Cpi veins

Mafic granulites

Amphibolite with corundum occur as lens, up to 100 m. thicktectonic contact with surroundig rocks, peridotites and mafic granulites

500 m

Fault Fault

The field trip observations

Amphibolite with corundum occur as lens, up to 100 m. thicktectonic contact with surroundig rocks, peridotites and mafic granulites

Mineral composition

Amphibole

Piroxene

Plagioclase

Plagioclase with 92.9-98.9% An (average 95.18)

Mineral composition

Corundum

Corundum contain 0.085-0.161% Cr2O3

Mineral compositionRock composition

Rock composition

Amphibole - plagioclase geothermometer (Blundy and Holland, 1990)

Degrees of metamorphism

8-12 kB, 820-10500C

Al content in Ho ( Hammerstorm and Zen, 1986)

6-12 kB

1000 T (0C)8006004000

4

8

12

16P

(kb

ar)

Qtz-absent

Qtz-present

W&N 91S&D 94

HblPl

Qtz

GrtCpxL

GrtCpx

Qtz

Pl PlOpx

Hbl

Qtz L

V

PlOpx

Qtz Cpx

Hbl

L Hbl+Qtz=Opx+Cpx+Pl+V

P&B 95R 93

C 88

E&T 86

W&W 94

N&C 00bN&C 00a

P 68,J 78 andWW 93

P&B 95B&L 91

CWT 67B 69

S 81

R 91

Experimental constraints

The maximum P-T condition still remains open. The most common mineral assemblage in the upper amphibolite facies for metabasites is Hbl+Pl±Qtz, with or without either Cpx or garnet.

The genesis of Corundum:

As a residue after partial melting as one of the liquides phases, with clinopyroxene and spinel or clinopyroxene and garnet for gabbroic anorthosite (Raheim&Green, 1974)

Metamorphic origin by reaction spinel+anorthite = corundum+diopside in rocks with sufficiently high Al2O3 content, e.g. a troctolitic protholith

This reaction needs spinel as one of the reactants, which may be formed by the raction olivine + plagioclase = orthopyroxene + clinopyroxene + spinel. (Kushiro&Yoder,1966)

Replacement of Hbl+Pl±Qtz by combinations of Cpx, Pl + corundum is the main task of this study.

Degrees of metamorphism

Whole-rock and mineral chemical compositions of AmC have cumulus origin, with a primary (?) mineral assemblage controlled by crystalization of olivine, plagioclase and clinopyroxene, as residue from primitive mantle (MORB source mantle ?).

Protolith

High Cr content (783-1090 ppm) imply formation from not evolved liquids.

Eu and Sr positive anomalies reflect plagioclase accumulation, protolith have a cumulus origin (olivine gabbro ?)

Subduction ?

High Cr content (783-1090 ppm) imply formation from not evolved liquids.

Eu and Sr positive anomalies reflect plagioclase accumulation, protolith have a cumulus origin (olivine gabbro ?)

Protolith

Whole-rock and mineral chemical compositions of AmC have cumulus origin, with a primary (?) mineral assemblage controlled by crystalization of olivine, plagioclase and clinopyroxene, as residue from primitive mantle (MORB source mantle ?).

The absence of thermal relaxation features in Amc require rapid exhumation.

Conclusions:

After cooling at shallow levels olivin gabbro cumulates , together with surrounding peridotites undergone subduction and metamorphose under amphibole-granulite-eclogite facies, most probably related with Jurassic subduction during formation of Dinaridic ophiolite belt.

During uplift and tectonical emplacement (closing of ocean space) the AmC was dismembered, forming fragments which were included in the ophiolite melange.

Whole rock compositions, with positive Eu and Sr anomalies indicate that protoliths of Amc have a basic composition, olivine gabbro cumulates (?)

Amphibilitewith corundum Peridotites with

Gr-Cpi veins Mafic granulites

Degrees of metamorphism of AmC and relation with ultramafic rocks is one of the important questions in genesis and emplacement of Dinaridic ophiolite belt.

Conclusions:

Ophiolites in Serbia and surrounding countries