Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements
Titanite is a common accessory mineral that is useful in determining both age (U-Pb isotopes) and pressure-temperature (P–T) conditions (trace-element composition: Zr, rare earth elements (REE)). However, titanite has a propensity to recrystallize during metamorphism, fluid flow, and deformation, wh...
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| Format: | Journal Article |
| Language: | English |
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ELSEVIER
2021
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| Online Access: | http://purl.org/au-research/grants/arc/DP160104637 http://hdl.handle.net/20.500.11937/91487 |
| _version_ | 1848765527692935168 |
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| author | Gordon, S.M. Kirkland, Chris Reddy, Steven Blatchford, H.J. Whitney, D.L. Teyssier, C. Evans, Noreen McDonald, B.J. |
| author_facet | Gordon, S.M. Kirkland, Chris Reddy, Steven Blatchford, H.J. Whitney, D.L. Teyssier, C. Evans, Noreen McDonald, B.J. |
| author_sort | Gordon, S.M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Titanite is a common accessory mineral that is useful in determining both age (U-Pb isotopes) and pressure-temperature (P–T) conditions (trace-element composition: Zr, rare earth elements (REE)). However, titanite has a propensity to recrystallize during metamorphism, fluid flow, and deformation, which can result in modifications to its isotopic and trace-element compositions. This modification has implications for the interpretation of titanite dates and the evaluation of pressure–temperature–time paths. The impact of deformation and recrystallization on trace-element mobility in titanite is investigated through microstructural and compositional mapping of titanite crystals from a sheared orthogneiss within an ultrahigh-pressure domain of the Western Gneiss Region (WGR), Norway. Results show that optically coherent titanite single crystals deformed in the dislocation creep regime and recrystallized by the process of grain-boundary migration, forming aggregates of titanite grains. Some of the aggregate grains record Caledonian-exhumation dates, whereas others have an inherited isotopic composition. Individual grains within the aggregate, regardless of their U-Pb isotopic composition, contain patchy zoning that formed during syn- to post-recrystallization fluid alteration and that is characterized by generally decreasing Ca and Ti and increasing Al and Fe from cores to rims. However, Zr and Sr concentrations are broadly zoned with respect to the long axis of the host crystal, without regard for the aggregate grain boundaries. REE do not show any obvious correlation with microstructure or age. These results indicate that many trace elements in titanite are unaffected by multi-stage, deformation-driven recrystallization; in contrast, Pb is variably mobile in these deformed titanite crystals. The combination of microstructural and high-spatial resolution geochemical and isotopic data reveals the potential extent of decoupling between the U-Pb isotopic system and the behavior of trace elements as pressure–temperature conditions change through time. |
| first_indexed | 2025-11-14T11:36:40Z |
| format | Journal Article |
| id | curtin-20.500.11937-91487 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:36:40Z |
| publishDate | 2021 |
| publisher | ELSEVIER |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-914872023-05-09T04:16:30Z Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements Gordon, S.M. Kirkland, Chris Reddy, Steven Blatchford, H.J. Whitney, D.L. Teyssier, C. Evans, Noreen McDonald, B.J. Science & Technology Physical Sciences Geochemistry & Geophysics titanite U-Pb geochronology trace elements deformation UHP terrane petrochronology Titanite is a common accessory mineral that is useful in determining both age (U-Pb isotopes) and pressure-temperature (P–T) conditions (trace-element composition: Zr, rare earth elements (REE)). However, titanite has a propensity to recrystallize during metamorphism, fluid flow, and deformation, which can result in modifications to its isotopic and trace-element compositions. This modification has implications for the interpretation of titanite dates and the evaluation of pressure–temperature–time paths. The impact of deformation and recrystallization on trace-element mobility in titanite is investigated through microstructural and compositional mapping of titanite crystals from a sheared orthogneiss within an ultrahigh-pressure domain of the Western Gneiss Region (WGR), Norway. Results show that optically coherent titanite single crystals deformed in the dislocation creep regime and recrystallized by the process of grain-boundary migration, forming aggregates of titanite grains. Some of the aggregate grains record Caledonian-exhumation dates, whereas others have an inherited isotopic composition. Individual grains within the aggregate, regardless of their U-Pb isotopic composition, contain patchy zoning that formed during syn- to post-recrystallization fluid alteration and that is characterized by generally decreasing Ca and Ti and increasing Al and Fe from cores to rims. However, Zr and Sr concentrations are broadly zoned with respect to the long axis of the host crystal, without regard for the aggregate grain boundaries. REE do not show any obvious correlation with microstructure or age. These results indicate that many trace elements in titanite are unaffected by multi-stage, deformation-driven recrystallization; in contrast, Pb is variably mobile in these deformed titanite crystals. The combination of microstructural and high-spatial resolution geochemical and isotopic data reveals the potential extent of decoupling between the U-Pb isotopic system and the behavior of trace elements as pressure–temperature conditions change through time. 2021 Journal Article http://hdl.handle.net/20.500.11937/91487 10.1016/j.epsl.2021.116810 English http://purl.org/au-research/grants/arc/DP160104637 http://purl.org/au-research/grants/arc/LE130100053 ELSEVIER fulltext |
| spellingShingle | Science & Technology Physical Sciences Geochemistry & Geophysics titanite U-Pb geochronology trace elements deformation UHP terrane petrochronology Gordon, S.M. Kirkland, Chris Reddy, Steven Blatchford, H.J. Whitney, D.L. Teyssier, C. Evans, Noreen McDonald, B.J. Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements |
| title | Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements |
| title_full | Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements |
| title_fullStr | Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements |
| title_full_unstemmed | Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements |
| title_short | Deformation-enhanced recrystallization of titanite drives decoupling between U-Pb and trace elements |
| title_sort | deformation-enhanced recrystallization of titanite drives decoupling between u-pb and trace elements |
| topic | Science & Technology Physical Sciences Geochemistry & Geophysics titanite U-Pb geochronology trace elements deformation UHP terrane petrochronology |
| url | http://purl.org/au-research/grants/arc/DP160104637 http://purl.org/au-research/grants/arc/DP160104637 http://hdl.handle.net/20.500.11937/91487 |