Hofmann, Amy E. and Valley, John W. and Watson, E. Bruce and Cavosie, Aaron J. and Eiler, John M. (2009) Sub-micron scale distributions of trace elements in zircon. Contributions to Mineralogy and Petrology, 158 (3). pp. 317-335. ISSN 0010-7999 http://resolver.caltech.edu/CaltechAUTHORS:20090808-142504369
- Published Version
Restricted to Repository administrators only
See Usage Policy.
Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20090808-142504369
Sub-micron scale zoning of Ti concentrations and correlations between concentrations of Ti and other trace elements (P, Ce, and Y) and cathodoluminescent (CL) banding is observed in natural zircons. Ion images were made using the Caltech Microanalysis Center’s CAMECA NanoSIMS 50L with an O− primary beam focused to ~300 nm on the sample surface. The high spatial resolution of this technique allows for interrogation of chemical variations at or below the scale of CL banding in natural zircons. Images produced in this manner display two types of correlations among Ti, P, Ce, and Y (which appears to be a proxy for CL intensity): strong (correlation coefficients >0.8) and subtle (correlation coefficients ~0.15–0.4). Strongly correlated images, which display Ti variations of ca. a factor of 3 between adjacent CL bands and overall elevated trace element concentrations in CL-dark bands, were found within an oscillatory-zoned, trace element enriched sector of a CL sector-zoned zircon. Three possible causes for such correlations include: temperature-dependent equilibrium partitioning, trace element partitioning limited by diffusion in the host melt and surface-controlled, non-equilibrium growth. Comparison of our data with the expected results of these processes suggests that: (1) Ti partitioning in zircon is dependent upon non-equilibrium effects in addition to temperature and/or (2) the incorporation of elements that co-vary with Ti in zircon (e.g., Y, P and Ce) is also temperature-dependent. Sub-micron scale, high-Ti regions are also found within Proterozoic Adirondack and >4 Ga Jack Hills zircons as well as trace element enrichments (including Ti) along cracks within Jack Hills zircons.
|Additional Information:||© Springer 2009. Received: 11 August 2008 Accepted: 21 January 2009 Published online: 15 February 2009. The authors thank Yunbin Guan and Chi Ma for technical assistance on the NanoSIMS and FE-SEM, Mike Baker and Eric Essene for thoughtful comments on earlier versions of this manuscript, and M.E. Bickford and two anonymous reviewers for their constructive reviews. Financial support for this study was provided by a grant from the Moore Foundation to the Caltech Microanalysis Center.|
|Subject Keywords:||Zircon; Ti-in-zircon thermometry; NanoSIMS; Cathodoluminescence; Trace elements; Jack Hills|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||George Porter|
|Deposited On:||04 Sep 2009 16:28|
|Last Modified:||26 Dec 2012 11:10|
Repository Staff Only: item control page