Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy)
The metamorphic rocks of the Ivrea Zone in NW Italy preserve a deep crustal metamorphic field gradient. Application of quantitative phase equilibria methods to metapelitic rocks provides new constraints on the P–T conditions recorded in Val Strona di Omegna, Val Sesia and Val Strona di Postua. In Va...
| Main Authors: | , , , |
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| Format: | Journal Article |
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Wiley - Blackwell
2012
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| Online Access: | http://hdl.handle.net/20.500.11937/43871 |
| _version_ | 1848756832728776704 |
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| author | Redler, C. Johnson, Tim White, R. Kunz, B. |
| author_facet | Redler, C. Johnson, Tim White, R. Kunz, B. |
| author_sort | Redler, C. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The metamorphic rocks of the Ivrea Zone in NW Italy preserve a deep crustal metamorphic field gradient. Application of quantitative phase equilibria methods to metapelitic rocks provides new constraints on the P–T conditions recorded in Val Strona di Omegna, Val Sesia and Val Strona di Postua. In Val Strona di Omegna, the metapelitic rocks show a structural and mineralogical change from mica-schists with the common assemblage bi–mu–sill–pl–q–ilm ± liq at the lowest grades, through metatexitic migmatites (g–sill–bi–ksp–pl–q–ilm–liq) at intermediate grades, to complex diatexitic migmatites (g–sill–ru–bi–ksp–pl–q–ilm–liq) at the highest grades. Partial melting in the metapelitic rocks is consistent with melting via the breakdown of first muscovite then biotite. The metamorphic field gradient in Val Strona di Omegna is constrained to range from conditions of ~3.5–6.5 kbar at ˜650 °C to ~10–12 kbar at >900 °C. The peak P–T estimates, particularly for granulite facies conditions, are significantly higher than those of most earlier studies. In Val Sesia and Val Strona di Postua, cordierite-bearing rocks record the effects of contact metamorphism associated with the intrusion of a large mafic body (the Mafic Complex). The contact metamorphism occurred at lower pressures than the regional metamorphic peak and overprints the regional metamorphic assemblages. These relationships are consistent with the intrusion of the Mafic Complex having post dated the regional metamorphism and are inconsistent with a model of magmatic underplating as the cause of granulite facies metamorphism in the region. |
| first_indexed | 2025-11-14T09:18:28Z |
| format | Journal Article |
| id | curtin-20.500.11937-43871 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:18:28Z |
| publishDate | 2012 |
| publisher | Wiley - Blackwell |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-438712017-02-28T01:47:32Z Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) Redler, C. Johnson, Tim White, R. Kunz, B. Val Strona di Omegna phase equilibria modelling partial melting metapelitic rocks Ivrea Zone granulite facies regional metamorphism The metamorphic rocks of the Ivrea Zone in NW Italy preserve a deep crustal metamorphic field gradient. Application of quantitative phase equilibria methods to metapelitic rocks provides new constraints on the P–T conditions recorded in Val Strona di Omegna, Val Sesia and Val Strona di Postua. In Val Strona di Omegna, the metapelitic rocks show a structural and mineralogical change from mica-schists with the common assemblage bi–mu–sill–pl–q–ilm ± liq at the lowest grades, through metatexitic migmatites (g–sill–bi–ksp–pl–q–ilm–liq) at intermediate grades, to complex diatexitic migmatites (g–sill–ru–bi–ksp–pl–q–ilm–liq) at the highest grades. Partial melting in the metapelitic rocks is consistent with melting via the breakdown of first muscovite then biotite. The metamorphic field gradient in Val Strona di Omegna is constrained to range from conditions of ~3.5–6.5 kbar at ˜650 °C to ~10–12 kbar at >900 °C. The peak P–T estimates, particularly for granulite facies conditions, are significantly higher than those of most earlier studies. In Val Sesia and Val Strona di Postua, cordierite-bearing rocks record the effects of contact metamorphism associated with the intrusion of a large mafic body (the Mafic Complex). The contact metamorphism occurred at lower pressures than the regional metamorphic peak and overprints the regional metamorphic assemblages. These relationships are consistent with the intrusion of the Mafic Complex having post dated the regional metamorphism and are inconsistent with a model of magmatic underplating as the cause of granulite facies metamorphism in the region. 2012 Journal Article http://hdl.handle.net/20.500.11937/43871 Wiley - Blackwell restricted |
| spellingShingle | Val Strona di Omegna phase equilibria modelling partial melting metapelitic rocks Ivrea Zone granulite facies regional metamorphism Redler, C. Johnson, Tim White, R. Kunz, B. Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) |
| title | Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) |
| title_full | Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) |
| title_fullStr | Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) |
| title_full_unstemmed | Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) |
| title_short | Phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the Ivrea Zone (NW Italy) |
| title_sort | phase equilibrium constraints on a deep crustal metamorphic field gradient: metapelitic rocks from the ivrea zone (nw italy) |
| topic | Val Strona di Omegna phase equilibria modelling partial melting metapelitic rocks Ivrea Zone granulite facies regional metamorphism |
| url | http://hdl.handle.net/20.500.11937/43871 |