Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria)
Podiform chromitite bodies occur in highly serpentinized peridotites at Dobromirtsi Ultramafic Massif (Rhodope Mountains, southeastern Bulgaria). The ultramafic body is believed to represent a fragment of Palaeozoic ophiolite mantle. The ophiolite sequence is associated with greenschist - lower-temp...
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| Format: | Article |
| Language: | English |
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Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)
2009-10-01
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| Series: | Geologica Acta |
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| Online Access: | https://revistes.ub.edu/index.php/GEOACTA/article/view/2068 |
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| author | J.M. GONZÁLEZ JIMÉNEZ T. KERESTEDJIAN J.A. PROENZA FERNÁNDEZ F. GERVILLA LINARES |
| author_facet | J.M. GONZÁLEZ JIMÉNEZ T. KERESTEDJIAN J.A. PROENZA FERNÁNDEZ F. GERVILLA LINARES |
| author_sort | J.M. GONZÁLEZ JIMÉNEZ |
| collection | DOAJ |
| description | Podiform chromitite bodies occur in highly serpentinized peridotites at Dobromirtsi Ultramafic Massif (Rhodope Mountains, southeastern Bulgaria). The ultramafic body is believed to represent a fragment of Palaeozoic ophiolite mantle. The ophiolite sequence is associated with greenschist - lower-temperature amphibolite facies metamorphosed rocks (biotitic gneisses hosting amphibolite). This association suggests that peridotites, chromitites and metamorphic rocks underwent a common metamorphic evolution. Chromitites at Dobromirtsi have been strongly altered. Their degree of alteration depends on the chromite/silicate ratio and to a lesser extent, on the size of chromitite bodies. Alteration is recorded in individual chromite grains in the form of optical and chemical zoning. Core to rim chemical trends are expressed by MgO- and Al2O3- impoverish-ment, mainly compensated by FeO and/or Fe2O3 increases. Such chemical variations correspond with threemain alteration events. The first one was associated with ocean-floor metamorphism and was characterized by alizardite replacement of olivine and the absence of chromite alteration. The second event took place duringgreenchist facies metamorphism. During this event, MgO- and SiO2- rich fluids (derived from low temperatureserpentinization of olivine and pyroxenes) reacted with chromite to form chlorite; as a consequence, chromitebecame altered to a FeO- and Cr2O3- rich, Al2O3- poor chromite. The third event, mainly developed during lowertemperature amphibolite facies metamorphism, caused the replacement of the primary and previously alteredchromite by Fe2O3- rich chromite (ferritchromite). |
| first_indexed | 2024-03-11T17:02:43Z |
| format | Article |
| id | doaj.art-d771b891c98e41c18c9bfff3e5a59f03 |
| institution | Directory Open Access Journal |
| issn | 1696-5728 |
| language | English |
| last_indexed | 2024-03-11T17:02:43Z |
| publishDate | 2009-10-01 |
| publisher | Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB) |
| record_format | Article |
| series | Geologica Acta |
| spelling | doaj.art-d771b891c98e41c18c9bfff3e5a59f032023-10-20T07:16:13ZengUniversitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)Geologica Acta1696-57282009-10-0174Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria)J.M. GONZÁLEZ JIMÉNEZ0T. KERESTEDJIAN1J.A. PROENZA FERNÁNDEZ2F. GERVILLA LINARES3Departamento de Mineralogía y Petrología and Instituto Andaluz de Ciencias de la Tierra (Universidad de Granada-CSIC), Facultad de CienciasAvda. Fuentenueva s/n, 18002 Granada, Spain.Geological Institute, Bulgarian Academy of Sciences24 Georgi Bonchev Str., 1113 Sofia, Bulgaria.Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de BarcelonaMartí i Franquès s/n, 08028 Barcelona, Spain.Departamento de Mineralogía y Petrología and Instituto Andaluz de Ciencias de la Tierra (Universidad de Granada-CSIC), Facultad de CienciasAvda. Fuentenueva s/n, 18002 Granada, Spain.Podiform chromitite bodies occur in highly serpentinized peridotites at Dobromirtsi Ultramafic Massif (Rhodope Mountains, southeastern Bulgaria). The ultramafic body is believed to represent a fragment of Palaeozoic ophiolite mantle. The ophiolite sequence is associated with greenschist - lower-temperature amphibolite facies metamorphosed rocks (biotitic gneisses hosting amphibolite). This association suggests that peridotites, chromitites and metamorphic rocks underwent a common metamorphic evolution. Chromitites at Dobromirtsi have been strongly altered. Their degree of alteration depends on the chromite/silicate ratio and to a lesser extent, on the size of chromitite bodies. Alteration is recorded in individual chromite grains in the form of optical and chemical zoning. Core to rim chemical trends are expressed by MgO- and Al2O3- impoverish-ment, mainly compensated by FeO and/or Fe2O3 increases. Such chemical variations correspond with threemain alteration events. The first one was associated with ocean-floor metamorphism and was characterized by alizardite replacement of olivine and the absence of chromite alteration. The second event took place duringgreenchist facies metamorphism. During this event, MgO- and SiO2- rich fluids (derived from low temperatureserpentinization of olivine and pyroxenes) reacted with chromite to form chlorite; as a consequence, chromitebecame altered to a FeO- and Cr2O3- rich, Al2O3- poor chromite. The third event, mainly developed during lowertemperature amphibolite facies metamorphism, caused the replacement of the primary and previously alteredchromite by Fe2O3- rich chromite (ferritchromite).https://revistes.ub.edu/index.php/GEOACTA/article/view/2068OphioliteChromiteMetamorphismDobromirtsi Ultramafic MassifBulgaria |
| spellingShingle | J.M. GONZÁLEZ JIMÉNEZ T. KERESTEDJIAN J.A. PROENZA FERNÁNDEZ F. GERVILLA LINARES Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) Geologica Acta Ophiolite Chromite Metamorphism Dobromirtsi Ultramafic Massif Bulgaria |
| title | Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) |
| title_full | Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) |
| title_fullStr | Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) |
| title_full_unstemmed | Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) |
| title_short | Metamorphism on Chromite Ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria) |
| title_sort | metamorphism on chromite ores from the dobromirtsi ultramafic massif rhodope mountains se bulgaria |
| topic | Ophiolite Chromite Metamorphism Dobromirtsi Ultramafic Massif Bulgaria |
| url | https://revistes.ub.edu/index.php/GEOACTA/article/view/2068 |
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