Presentation on theme: "Petrology and metamorphism of amphibolites"— Presentation transcript:
1 Petrology and metamorphism of amphibolites Milovanović Dragan.,Eric Suzana.,Seke Lajos.Petrology and metamorphism of amphiboliteswith corundum from Prijepolje , Dinaridic ophioliteBelt (Southwestern Serbia)
2 Geographic position of Serbia on Balkan Peninsula T HK A RP AAB A L KE SON IDA L P SD I N A R I D E SA P E N I N E S
3 The Mesozoic ophiolites in Serbia TISSIA BelgradeVardar zoneJadarblockVardar zoneAmphiboliteswith corundumDinaride ophiolite beltDrina IvanjicaterranVardar zone
4 The Mesozoic ophiolites in Serbia TISSIA Pillow lavasBelgradeVardar zoneTriassic limestoneJadarblockTriassiclimestoneZlatibor peridotitesVardar zoneAmphiboliteswith corundumAmphiboliteswith corundumDinaride ophiolite beltDrina IvanjicaterranPeridotitesVardar zoneOphiolitic melange
5 The field trip observations Amphibolite with corundum occur as lens, up to 100 m. thicktectonic contact with surroundig rocks, peridotites and mafic granulitesAmphibilitewith corundumPeridotites withGr-Cpi veinsMafic granulitesFaultFault500 m
6 Mineral composition The field trip observations Amphibolite with corundum occur as lens, up to 100 m. thicktectonic contact with surroundig rocks, peridotites and mafic granulites
7 Mineral composition Plagioclase with 92.9-98.9% An (average 95.18) PiroxenePlagioclaseAmphibole
8 Rock composition Mineral composition Corundum contain % Cr2O3Corundum
10 8-12 kB, 820-10500C Degrees of metamorphism 1000T (0C)800600400481216P (kbar)Qtz-absentQtz-presentW&N 91S&D 94HblPlQtzGrtCpxLOpxVHbl+Qtz=Opx+Cpx+Pl+VP&B 95R 93C 88E&T 86W&W 94N&C 00bN&C 00aP 68,J 78 andWW 93B&L 91CWT 67B 69S 81R 91Experimental constraintsAmphibole - plagioclase geothermometer(Blundy and Holland, 1990)8-12 kB, CAl content in Ho ( Hammerstorm and Zen, 1986)6-12 kB
11 Degrees of metamorphism The genesis of Corundum:As a residue after partial melting as one of the liquides phases, with clinopyroxene andspinel or clinopyroxene and garnet for gabbroic anorthosite (Raheim&Green, 1974)Metamorphic origin by reaction spinel+anorthite = corundum+diopside in rocks withsufficiently high Al2O3 content, e.g. a troctolitic protholithThis reaction needs spinel as one of the reactants, which may be formed by the ractionolivine + plagioclase = orthopyroxene + clinopyroxene + spinel. (Kushiro&Yoder,1966)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.Replacement of Hbl+Pl±Qtz by combinations of Cpx, Pl + corundum is the main task of this study.
12 ProtolithSubduction ?Eu and Sr positive anomalies reflect plagioclase accumulation, protolith have a cumulus origin (olivine gabbro ?)High Cr content ( ppm) imply formation from not evolved liquids.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 ?).
13 ProtolithEu and Sr positive anomalies reflect plagioclase accumulation, protolith have a cumulus origin (olivine gabbro ?)High Cr content ( ppm) imply formation from not evolved liquids.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 ?).
14 Conclusions:Whole rock compositions, with positive Eu and Sr anomalies indicate that protoliths of Amc have a basic composition, olivine gabbro cumulates (?)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.The absence of thermal relaxation features in Amc require rapid exhumation.Amphibilitewith corundumPeridotites withGr-Cpi veinsMaficgranulites
15 Ophiolites in Serbia and surrounding countries Conclusions:Ophiolites in Serbia and surrounding countriesDinaridicVardar zoneophiolitebeltDegrees of metamorphism of AmC and relation with ultramafic rocks is one of the important questions in genesis and emplacement of Dinaridic ophiolite belt.
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