The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation
In this paper we present new data on the spatial variability of peridotite composition across a kilometer-scale mantle shear zone within the Lanzo massif (Western Alps, Italy). The shear zone separates the central from the northern part of the massif. Plagioclase peridotite shows gradually increasin...
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| Format: | Journal Article |
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Springer
2010
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| Online Access: | http://hdl.handle.net/20.500.11937/4014 |
| _version_ | 1848744395024629760 |
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| author | Kaczmarek, Mary-Alix Muentener, O. |
| author_facet | Kaczmarek, Mary-Alix Muentener, O. |
| author_sort | Kaczmarek, Mary-Alix |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | In this paper we present new data on the spatial variability of peridotite composition across a kilometer-scale mantle shear zone within the Lanzo massif (Western Alps, Italy). The shear zone separates the central from the northern part of the massif. Plagioclase peridotite shows gradually increasing deformation towards the shear zone, from porphyroclastic to mylonitic textures in the central body, while the northern body is composed of porphyroclastic rocks. The peridotite displays a large range of compositions, from fertile peridotite to refractory harzburgite and dunite. Deformed peridotites (proto-mylonite and mylonites) tend to be compositionally more homogeneous and fertile than weakly deformed peridotites.The composition of most plagioclase peridotites show rather high and constant (Ce/Yb) N ratios, and Yb N that cannot be explained by any simple melting model. Instead, refertilization modeling, consisting of melt increments from spinel peridotite sources, particularly with E-MORB melt, reasonably reproduces the plagioclase peridotite whole rock composition. Combined with constraints from Ce–Nb and Ce–Th systematics, we speculate that peridotites such as those from Lanzo record pervasive refertilization processes in the thermal boundary layer. In this scenario, mantle shear zones might act as important areas of melt focusing in the upper mantle that separates the thermal boundary layer from the conductively cooled mantle. |
| first_indexed | 2025-11-14T06:00:47Z |
| format | Journal Article |
| id | curtin-20.500.11937-4014 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:00:47Z |
| publishDate | 2010 |
| publisher | Springer |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-40142017-09-13T16:06:40Z The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation Kaczmarek, Mary-Alix Muentener, O. Plagioclase peridotite - Shear zone - Melt rock reaction - Melt focusing - Whole rock composition - Refertilization - Lanzo peridotite In this paper we present new data on the spatial variability of peridotite composition across a kilometer-scale mantle shear zone within the Lanzo massif (Western Alps, Italy). The shear zone separates the central from the northern part of the massif. Plagioclase peridotite shows gradually increasing deformation towards the shear zone, from porphyroclastic to mylonitic textures in the central body, while the northern body is composed of porphyroclastic rocks. The peridotite displays a large range of compositions, from fertile peridotite to refractory harzburgite and dunite. Deformed peridotites (proto-mylonite and mylonites) tend to be compositionally more homogeneous and fertile than weakly deformed peridotites.The composition of most plagioclase peridotites show rather high and constant (Ce/Yb) N ratios, and Yb N that cannot be explained by any simple melting model. Instead, refertilization modeling, consisting of melt increments from spinel peridotite sources, particularly with E-MORB melt, reasonably reproduces the plagioclase peridotite whole rock composition. Combined with constraints from Ce–Nb and Ce–Th systematics, we speculate that peridotites such as those from Lanzo record pervasive refertilization processes in the thermal boundary layer. In this scenario, mantle shear zones might act as important areas of melt focusing in the upper mantle that separates the thermal boundary layer from the conductively cooled mantle. 2010 Journal Article http://hdl.handle.net/20.500.11937/4014 10.1007/s00410-010-0500-8 Springer restricted |
| spellingShingle | Plagioclase peridotite - Shear zone - Melt rock reaction - Melt focusing - Whole rock composition - Refertilization - Lanzo peridotite Kaczmarek, Mary-Alix Muentener, O. The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation |
| title | The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation |
| title_full | The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation |
| title_fullStr | The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation |
| title_full_unstemmed | The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation |
| title_short | The variability of peridotite composition across a mantle shear zone (Lanzo massif, Italy): interplay of melt focusing and deformation |
| title_sort | variability of peridotite composition across a mantle shear zone (lanzo massif, italy): interplay of melt focusing and deformation |
| topic | Plagioclase peridotite - Shear zone - Melt rock reaction - Melt focusing - Whole rock composition - Refertilization - Lanzo peridotite |
| url | http://hdl.handle.net/20.500.11937/4014 |