Abstract
Element mobility is a critical component in all geological processes and understanding the mechanisms responsible for element mobility in minerals is a fundamental requirement for many geochemical and geochronological applications. Volume diffusion of elements is a commonly assumed process. However, linear defects (dislocations) are an essential component of the high-temperature creep of minerals. These defects are commonly inferred to form fast-diffusion pathways along which trace elements can more rapidly migrate. In contrast, dislocations in minerals are also energetically favourable sites of trace element segregation, which counters the notion that they enhance bulk diffusion rates by a pipe diffusion mechanism. In this paper we characterize the trace-element composition of dislocations on twin boundaries in rutile by combining atom probe tomography with transmission electron microscopy. First, morphology and correlative microstructural data are used to demonstrate that the linear compositional features in the atom probe tomography dataset represent dislocations. Assessment of dislocation composition indicates that segregation is trace element specific. The data show that dislocations in rutile act as both, fast-diffusion pathway and trace-element traps which potentially leads to erroneous estimations of the composition.
| Originalsprog | Engelsk |
|---|---|
| Artikelnummer | 117517 |
| Tidsskrift | Earth and Planetary Science Letters |
| Vol/bind | 584 |
| Antal sider | 10 |
| ISSN | 0012-821X |
| DOI | |
| Status | Udgivet - 2022 |
| Udgivet eksternt | Ja |
Bibliografisk note
Funding Information:We thank Professor Pat James for providing samples and field photos, which were collected during the 1979/80 Australian National Antarctic Research Expedition to Enderby Land. We would also like to thank Renelle Dubosq, Phillip Gopon and the anonymous reviewers for their helpful insights and feedback. The work was conducted within the Geoscience Atom Probe Facility in the John de Laeter Centre, Curtin University. The authors gratefully acknowledge support of Curtin University’s Microscopy & Microanalysis Facility and the John de Laeter Centre, whose instrumentation has been supported by University, State and Commonwealth Government funding. The GeoHistory Facility is supported by AuScope ( auscope.org.au ) and the Australian Government via the National Collaborative Research Infrastructure Strategy (NCRIS). The development of the Geoscience Atom Probe Facility was supported by the Curtin University , UWA and CSIRO and the Science and Industry Endowment Fund (SIEF) through Grant SIEF RI13-01 . SMR and DWS gratefully acknowledge ARC grant DP210102625 . DF is supported by ARC DE190101307 .
Publisher Copyright:
© 2022 Elsevier B.V.