Trace Element Behavior during Shock Transformation of Zircon to Reidite
A. A. Shiryaev, A. N. Zhukov, V. V. Yakushev, A. A. Averin, V. O. Yapaskurt, A. Yu. Borisova, A. Yu. Bychkov, O. G. Safonov, I. V. Lomonosov
公開日: 2025/9/27
Abstract
Large single crystals of natural zircon were shock-loaded at 13.6 and 51.3 GPa in planar geometry. No structural changes were observed after loading at 13.6 GPa. Loading to 51.3 GPa resulted in zircon transformation to a denser scheelite-structured phase, reidite. The investigation of reidite samples by X-ray diffraction, Raman, photo- and cathodoluminescence spectroscopies revealed segregation of some trace cations (such as REE) on planar defects during the transformation. The segregation has occurred in a laboratory experiment without long-term annealing after the shock loading. A possible mechanism of the segregation of trivalent trace cations assumes local violation of charge balance during the zircon-reidite reconstructive transformation, which is accompanied by changes in the topology of polyhedra and second coordination spheres (Si-Zr). This results in expulsion of a fraction of the trace elements into energetically expensive interstitial positions with high diffusivity even at relatively low temperatures.