Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite
Large-scale metasomatic albitization in the albitite terranes of the Bamble sector of southeastern Norway has affected both mafic and granitic lithologies. In partially metasomatized tonalite, the albitization fronts advance normal to fractures and can be recognized in the field by a distinct redden...
| Main Authors: | , , , |
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| Format: | Journal Article |
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Mineralogical Association of Canada
2008
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| Online Access: | http://hdl.handle.net/20.500.11937/34647 |
| _version_ | 1848754280075362304 |
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| author | Engvik, A. Putnis, Andrew Fitz Gerald, J. Austrheim, H. |
| author_facet | Engvik, A. Putnis, Andrew Fitz Gerald, J. Austrheim, H. |
| author_sort | Engvik, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Large-scale metasomatic albitization in the albitite terranes of the Bamble sector of southeastern Norway has affected both mafic and granitic lithologies. In partially metasomatized tonalite, the albitization fronts advance normal to fractures and can be recognized in the field by a distinct reddening of the rock in which original plagioclase crystals are replaced by albite. To determine the mechanism of albitization within single crystals of Ca-bearing plagioclase (oligoclase: An21-23), intragranular replacement interfaces have been studied by electron-probe micro-analysis, scanning (SEM) and transmission electron microscopy (TEM). The albite replacement-product (An2-5) has micrometric pores observable by SEM, as well as nanopores imaged by TEM. The albite contains fine-grained white mica commonly associated with the pores, as well as precipitates of hematite. The interface between oligoclase and albite is sharp, with corresponding compositional gradients across no more than tens of nanometers, and the crystallographic orientations of oligoclase and albite are coincident within less than a degree. These are all characteristic features of an interface-coupled dissolution-reprecipitation mechanism of replacement which, in combination with fracturing, is responsible for the fluid infiltration and the mineral-replacement process. |
| first_indexed | 2025-11-14T08:37:54Z |
| format | Journal Article |
| id | curtin-20.500.11937-34647 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:37:54Z |
| publishDate | 2008 |
| publisher | Mineralogical Association of Canada |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-346472017-09-13T15:11:57Z Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite Engvik, A. Putnis, Andrew Fitz Gerald, J. Austrheim, H. Large-scale metasomatic albitization in the albitite terranes of the Bamble sector of southeastern Norway has affected both mafic and granitic lithologies. In partially metasomatized tonalite, the albitization fronts advance normal to fractures and can be recognized in the field by a distinct reddening of the rock in which original plagioclase crystals are replaced by albite. To determine the mechanism of albitization within single crystals of Ca-bearing plagioclase (oligoclase: An21-23), intragranular replacement interfaces have been studied by electron-probe micro-analysis, scanning (SEM) and transmission electron microscopy (TEM). The albite replacement-product (An2-5) has micrometric pores observable by SEM, as well as nanopores imaged by TEM. The albite contains fine-grained white mica commonly associated with the pores, as well as precipitates of hematite. The interface between oligoclase and albite is sharp, with corresponding compositional gradients across no more than tens of nanometers, and the crystallographic orientations of oligoclase and albite are coincident within less than a degree. These are all characteristic features of an interface-coupled dissolution-reprecipitation mechanism of replacement which, in combination with fracturing, is responsible for the fluid infiltration and the mineral-replacement process. 2008 Journal Article http://hdl.handle.net/20.500.11937/34647 10.3749/canmin.46.6.1401 Mineralogical Association of Canada restricted |
| spellingShingle | Engvik, A. Putnis, Andrew Fitz Gerald, J. Austrheim, H. Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite |
| title | Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite |
| title_full | Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite |
| title_fullStr | Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite |
| title_full_unstemmed | Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite |
| title_short | Albitization of granitic rocks: The mechanism of replacement of oligoclase by albite |
| title_sort | albitization of granitic rocks: the mechanism of replacement of oligoclase by albite |
| url | http://hdl.handle.net/20.500.11937/34647 |