Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy)
Petrographic and geochemical data for mylonites from a metric-scale shear zone in mantle peridotites from the Finero massif (Southern Alps) record large mineralogical and geochemical modifications compared to surrounding coarse-grained ultramafic rocks, which were pervasively deformed in presence of...
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MDPI AG
2020-05-01
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| Series: | Geosciences |
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| Online Access: | https://www.mdpi.com/2076-3263/10/5/196 |
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| author | Stefania Corvò Antonio Langone José Alberto Padrón-Navarta Andrea Tommasi Alberto Zanetti |
| author_facet | Stefania Corvò Antonio Langone José Alberto Padrón-Navarta Andrea Tommasi Alberto Zanetti |
| author_sort | Stefania Corvò |
| collection | DOAJ |
| description | Petrographic and geochemical data for mylonites from a metric-scale shear zone in mantle peridotites from the Finero massif (Southern Alps) record large mineralogical and geochemical modifications compared to surrounding coarse-grained ultramafic rocks, which were pervasively deformed in presence of hydrous melts. The mylonites are composed by olivine and orthopyroxene and, less frequently, clinopyroxene, phlogopite, and pargasite porphyroclasts enclosed in a fine-grained matrix of phlogopite and olivine, with subordinate amounts of orthopyroxene, clinopyroxene, pargasite, and chromite. P-T estimates indicate that deformation occurred under granulite- to upper-amphibolite facies conditions. Field relationships and U-Pb dating indicate that the shear zone was active during Lower Jurassic and/or later, in an extensional setting at the western margin of the Adria plate, which led to the opening of the Alpine Tethys. The major and trace element composition of the porphyroclasts in the mylonites significantly differ from those in the hosting coarse-grained ultramafics. Porphyroclasts were chemically active during deformation acting as source (diffusion-out) or sink (diffusion-in) for some trace elements. The chemical modifications were promoted by the interaction with aqueous fluids and the composition varied from mantle- (enriched in Ni, Co, Li, Na, REE, Y, and Sr) to crustal-derived (enriched in Zn, K, Al, Ti, and Fe). |
| first_indexed | 2024-03-10T19:41:43Z |
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| id | doaj.art-5e2e8419cc5a49679ef3343247faa1a2 |
| institution | Directory Open Access Journal |
| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-10T19:41:43Z |
| publishDate | 2020-05-01 |
| publisher | MDPI AG |
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| series | Geosciences |
| spelling | doaj.art-5e2e8419cc5a49679ef3343247faa1a22023-11-20T01:12:48ZengMDPI AGGeosciences2076-32632020-05-0110519610.3390/geosciences10050196Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy)Stefania Corvò0Antonio Langone1José Alberto Padrón-Navarta2Andrea Tommasi3Alberto Zanetti4Department of Earth and Environmental Sciences, University of Pavia, 27100 Pavia, ItalyInstitute of Geosciences and Earth Resources, National Research Council (C.N.R), 27100 Pavia, ItalyGéosciences Montpellier, Univ. Montpellier & CNRS, 34090 Montpellier, FranceGéosciences Montpellier, Univ. Montpellier & CNRS, 34090 Montpellier, FranceInstitute of Geosciences and Earth Resources, National Research Council (C.N.R), 27100 Pavia, ItalyPetrographic and geochemical data for mylonites from a metric-scale shear zone in mantle peridotites from the Finero massif (Southern Alps) record large mineralogical and geochemical modifications compared to surrounding coarse-grained ultramafic rocks, which were pervasively deformed in presence of hydrous melts. The mylonites are composed by olivine and orthopyroxene and, less frequently, clinopyroxene, phlogopite, and pargasite porphyroclasts enclosed in a fine-grained matrix of phlogopite and olivine, with subordinate amounts of orthopyroxene, clinopyroxene, pargasite, and chromite. P-T estimates indicate that deformation occurred under granulite- to upper-amphibolite facies conditions. Field relationships and U-Pb dating indicate that the shear zone was active during Lower Jurassic and/or later, in an extensional setting at the western margin of the Adria plate, which led to the opening of the Alpine Tethys. The major and trace element composition of the porphyroclasts in the mylonites significantly differ from those in the hosting coarse-grained ultramafics. Porphyroclasts were chemically active during deformation acting as source (diffusion-out) or sink (diffusion-in) for some trace elements. The chemical modifications were promoted by the interaction with aqueous fluids and the composition varied from mantle- (enriched in Ni, Co, Li, Na, REE, Y, and Sr) to crustal-derived (enriched in Zn, K, Al, Ti, and Fe).https://www.mdpi.com/2076-3263/10/5/196mantle peridotiteshear zonemajor and trace elementsmyloniteporphyroclastsIvrea-Verbano Zone |
| spellingShingle | Stefania Corvò Antonio Langone José Alberto Padrón-Navarta Andrea Tommasi Alberto Zanetti Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy) Geosciences mantle peridotite shear zone major and trace elements mylonite porphyroclasts Ivrea-Verbano Zone |
| title | Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy) |
| title_full | Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy) |
| title_fullStr | Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy) |
| title_full_unstemmed | Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy) |
| title_short | Porphyroclasts: Source and Sink of Major and Trace Elements During Deformation-Induced Metasomatism (Finero, Ivrea-Verbano Zone, Italy) |
| title_sort | porphyroclasts source and sink of major and trace elements during deformation induced metasomatism finero ivrea verbano zone italy |
| topic | mantle peridotite shear zone major and trace elements mylonite porphyroclasts Ivrea-Verbano Zone |
| url | https://www.mdpi.com/2076-3263/10/5/196 |
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