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In situ observations of the zircon-reidite transition in ZrSiO4 were carried out using a multianvil high-pressure apparatus and synchrotron radiation. The phase boundary between zircon and reidite was determined to be P (GPa) = 8.5 + 0.0017×(T-1200) (K) for temperatures between 1100-1900 K. When subducted slabs, including igneous rocks and sediments, descend into the upper mantle, zircon in the subducted slab transforms into reidite at pressures of about 9 GPa, corresponding to a depth of 270 km. Reidite found in an upper Eocene impact ejecta layer in marine sediments is thought to have been transformed from zircon by a shock event. The peak pressure generated by the shock event in this occurrence is estimated to be higher than 8 GPa.
northern KAZAKSTAN; METAMORPHIC ROCKS; ZRSIO4; TRANSFORMATIONS; POLYMORPH; REIDITE; STATE; GPA
Digital Object Identifer:10.1007/s00410-004-0570-6 Published with permission from the copyright holder. This is the author's copy, as published in Contributions to Mineralogy and Petrology, June 2004, Volume 147, Issue 4, Pages 505-509. Publisher URL:http://dx.doi.org/10.1007/s00410-004-0570-6 Direct access to Thomson Web of Science record Copyright © 2004 Springer-Verlag. All rights reserved.
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