Nanoscale processes of trace element mobility in metamorphosed zircon
© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Several examples of zircon grains from high- to ultrahigh-pressure (UHP) and ultrahigh-temperature (UHT) metapelites exhibit a characteristic, yet atypical, core–rim interface domain < 5-μm wide observed in cathodoluminescence (CL) im...
| Main Authors: | , , , , , |
|---|---|
| Format: | Journal Article |
| Language: | English |
| Published: |
SPRINGER
2019
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.11937/79364 |
| _version_ | 1848764038518931456 |
|---|---|
| author | Peterman, E.M. Reddy, Steven Saxey, David Fougerouse, Denis Snoeyenbos, D.R. Rickard, William |
| author_facet | Peterman, E.M. Reddy, Steven Saxey, David Fougerouse, Denis Snoeyenbos, D.R. Rickard, William |
| author_sort | Peterman, E.M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | © 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Several examples of zircon grains from high- to ultrahigh-pressure (UHP) and ultrahigh-temperature (UHT) metapelites exhibit a characteristic, yet atypical, core–rim interface domain < 5-μm wide observed in cathodoluminescence (CL) imaging. The interface domain is located immediately against the magmatic core and is comprised of an irregular, 0–2-μm wide, CL-dark domain that is rimmed by a complex, 0–5-μm wide, CL-bright domain with cuspate margins. The outer margin of the interface domain is rimmed by intermediate-CL zircon with low contrast zoning. To characterize the nature of the interface domain and to identify mechanisms of trace element mobility in metamorphosed zircon, we analyzed several specimens prepared from zircon from the Rhodope Metamorphic Complex (eastern Greece) and the Goshen Dome (western Massachusetts, USA) via atom probe tomography (APT). The data reveal three types of geochemical anomalies, each with a unique morphology. (1) Toroidal clusters with high concentrations of Pb (+ Y, Al) are found exclusively within the core of the Rhodope grain. These clusters are interpreted as decorated dislocation loops that formed during metamorphism and annealing of radiation damage to the lattice. Geochronological and geochemical data support this interpretation. (2) Complex, cross-cutting planar and linear features with anomalous concentrations of Y + P + Yb or U are spatially restricted to the core–rim interface domain; these features do not correlate with inherited geochemical variation (oscillatory zoning) or deformation-induced microstructures. Instead, the planar features likely formed in response to an interface-coupled dissolution–reprecipitation reaction that propagated into the crystal during metamorphism. The observed cross-cutting relationships are the product of either multiple events or complexity of the process that originally formed the domains. (3) Ellipsoidal features with high concentrations of Y + P + Yb (+ Al) are found exclusively within the high-Y + P + Yb planar features. These features are interpreted as the product of spinodal decomposition that occurred during exhumation as the zircon passed the solvus where local equilibria favored nm-scale exsolution to minimize the Gibbs free energy. The presence of multiple types of geochemical features in these examples indicates that trace element mobility in zircon is driven by multiple processes over the course of orogenesis. Given that these atypical domains are apparently restricted to zircon metamorphosed at UHT and (U)HP conditions, their presence may represent a marker of metamorphism at very high-grade conditions. |
| first_indexed | 2025-11-14T11:13:00Z |
| format | Journal Article |
| id | curtin-20.500.11937-79364 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:13:00Z |
| publishDate | 2019 |
| publisher | SPRINGER |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-793642020-09-03T00:56:35Z Nanoscale processes of trace element mobility in metamorphosed zircon Peterman, E.M. Reddy, Steven Saxey, David Fougerouse, Denis Snoeyenbos, D.R. Rickard, William Science & Technology Physical Sciences Geochemistry & Geophysics Mineralogy Zircon Atom probe tomography Nanoscale Interface-coupled dissolution-reprecipitation Trace element geochemistry Metamorphism ATOM-PROBE TOMOGRAPHY PARTIALLY METAMICT ZIRCON HIGH-GRADE METAMORPHISM RARE-EARTH-ELEMENTS U-PB GEOCHRONOLOGY RADIATION-DAMAGE DISSOLUTION-REPRECIPITATION PLASTIC-DEFORMATION ACCESSORY MINERALS MAGMATIC ZIRCON © 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Several examples of zircon grains from high- to ultrahigh-pressure (UHP) and ultrahigh-temperature (UHT) metapelites exhibit a characteristic, yet atypical, core–rim interface domain < 5-μm wide observed in cathodoluminescence (CL) imaging. The interface domain is located immediately against the magmatic core and is comprised of an irregular, 0–2-μm wide, CL-dark domain that is rimmed by a complex, 0–5-μm wide, CL-bright domain with cuspate margins. The outer margin of the interface domain is rimmed by intermediate-CL zircon with low contrast zoning. To characterize the nature of the interface domain and to identify mechanisms of trace element mobility in metamorphosed zircon, we analyzed several specimens prepared from zircon from the Rhodope Metamorphic Complex (eastern Greece) and the Goshen Dome (western Massachusetts, USA) via atom probe tomography (APT). The data reveal three types of geochemical anomalies, each with a unique morphology. (1) Toroidal clusters with high concentrations of Pb (+ Y, Al) are found exclusively within the core of the Rhodope grain. These clusters are interpreted as decorated dislocation loops that formed during metamorphism and annealing of radiation damage to the lattice. Geochronological and geochemical data support this interpretation. (2) Complex, cross-cutting planar and linear features with anomalous concentrations of Y + P + Yb or U are spatially restricted to the core–rim interface domain; these features do not correlate with inherited geochemical variation (oscillatory zoning) or deformation-induced microstructures. Instead, the planar features likely formed in response to an interface-coupled dissolution–reprecipitation reaction that propagated into the crystal during metamorphism. The observed cross-cutting relationships are the product of either multiple events or complexity of the process that originally formed the domains. (3) Ellipsoidal features with high concentrations of Y + P + Yb (+ Al) are found exclusively within the high-Y + P + Yb planar features. These features are interpreted as the product of spinodal decomposition that occurred during exhumation as the zircon passed the solvus where local equilibria favored nm-scale exsolution to minimize the Gibbs free energy. The presence of multiple types of geochemical features in these examples indicates that trace element mobility in zircon is driven by multiple processes over the course of orogenesis. Given that these atypical domains are apparently restricted to zircon metamorphosed at UHT and (U)HP conditions, their presence may represent a marker of metamorphism at very high-grade conditions. 2019 Journal Article http://hdl.handle.net/20.500.11937/79364 10.1007/s00410-019-1631-1 English SPRINGER restricted |
| spellingShingle | Science & Technology Physical Sciences Geochemistry & Geophysics Mineralogy Zircon Atom probe tomography Nanoscale Interface-coupled dissolution-reprecipitation Trace element geochemistry Metamorphism ATOM-PROBE TOMOGRAPHY PARTIALLY METAMICT ZIRCON HIGH-GRADE METAMORPHISM RARE-EARTH-ELEMENTS U-PB GEOCHRONOLOGY RADIATION-DAMAGE DISSOLUTION-REPRECIPITATION PLASTIC-DEFORMATION ACCESSORY MINERALS MAGMATIC ZIRCON Peterman, E.M. Reddy, Steven Saxey, David Fougerouse, Denis Snoeyenbos, D.R. Rickard, William Nanoscale processes of trace element mobility in metamorphosed zircon |
| title | Nanoscale processes of trace element mobility in metamorphosed zircon |
| title_full | Nanoscale processes of trace element mobility in metamorphosed zircon |
| title_fullStr | Nanoscale processes of trace element mobility in metamorphosed zircon |
| title_full_unstemmed | Nanoscale processes of trace element mobility in metamorphosed zircon |
| title_short | Nanoscale processes of trace element mobility in metamorphosed zircon |
| title_sort | nanoscale processes of trace element mobility in metamorphosed zircon |
| topic | Science & Technology Physical Sciences Geochemistry & Geophysics Mineralogy Zircon Atom probe tomography Nanoscale Interface-coupled dissolution-reprecipitation Trace element geochemistry Metamorphism ATOM-PROBE TOMOGRAPHY PARTIALLY METAMICT ZIRCON HIGH-GRADE METAMORPHISM RARE-EARTH-ELEMENTS U-PB GEOCHRONOLOGY RADIATION-DAMAGE DISSOLUTION-REPRECIPITATION PLASTIC-DEFORMATION ACCESSORY MINERALS MAGMATIC ZIRCON |
| url | http://hdl.handle.net/20.500.11937/79364 |