Meeting room "Glova", 4 floor, Integrated Research Building
Abstract
The Earth's internal dynamics drive materials from its surface into its deep interior, where those materials are believed to be recycled through various high-pressure and high-temperature processes including chemical and structural transformations but also melting in the deep mantle. Therefore, the HP-HT behaviors of sediments and crustal materials are of interest as they are candidate components for creating compositional and density heterogeneities in the Earth's mantle. In this regard, the CAS phase is a Ca-rich aluminosilicate that has been observed in the decomposition products of continental crust, basaltic compositions and anorthite system at high-P,T conditions (Irifune et al., 1994; Gautron et al., 1996; Hirose and Fei, 2002). Naturally occurring CAS phase has also been discovered in shocked martian meteorites (Beck et al., 2004). Thus, this phase might be an important constituent mineral of sediments and basalts subducted in the deep mantle. Here, we examinate the HP-HT behaviors of the CAS phase up to the P,T conditions of the lowermost transition zone by energy dispersive X-ray diffraction, using a Kawai-type multi-anvil press apparatus coupled with synchrotron radiation in SPring-8 (Japan). The high-P,T phase stability and pressure-volume-temperature relations of the CAS phase with the composition of CaAl4Si2O11 were examinated in situ up to 24 GPa and 2100 K. The present data enables the accurate estimate of density of the CAS phase in the deep mantle for various temperature profiles (i.e. adiabatic mantle or cold slab geotherms).
For inquiry：Taku Tsuchiya TEL:（089）927-8198
E-mail takut@sci.ehime-u.ac.jp
