Scapolites are common volatile-bearing minerals in metamorphic rocks. In this study, the high-pressure behavior of an intermediate member of the scapolite solid solution series (Me47), chemical formula (Na1.86Ca1.86K0.23Fe0.01)(Al4.36Si7.64)O24[Cl0.48(CO3)0.48(SO4)0.01], has been investigated up to 17.79 GPa, by means of in situ single-crystal synchrotron X-ray diffraction. The isothermal elastic behavior of the studied scapolite has been described by a III-order Birch–Murnaghan equation of state, which provided the following refined parameters: V0 = 1110.6(7) Å3, KV0 = 70(2) GPa (βV0 = 0.0143(4) GPa−1) and KV′ = 4.8(7). The refined bulk modulus is intermediate between those previously reported for Me17 and Me68 scapolite samples, confirming that the bulk compressibility among the solid solution increases with the Na content. A discussion on the P-induced structure deformation mechanisms of tetragonal scapolite at the atomic scale is provided, along with the implications of the reported results for the modeling of scapolite stability. In addition, a single-crystal to single-crystal phase transition, which is displacive in character, has been observed toward a triclinic polymorph at 9.87 GPa. The high-pressure triclinic polymorph was found to be stable up to the highest pressure investigated.

High-pressure behavior of intermediate scapolite : compressibility, structure deformation and phase transition / P. Lotti, D. Comboni, M. Merlini, M. Hanfland. - In: PHYSICS AND CHEMISTRY OF MINERALS. - ISSN 0342-1791. - 45:10(2018 Nov), pp. 945-962. [10.1007/s00269-018-0976-8]

High-pressure behavior of intermediate scapolite : compressibility, structure deformation and phase transition

Lotti, Paolo;Comboni, Davide;Merlini, Marco;
2018-11

Abstract

Scapolites are common volatile-bearing minerals in metamorphic rocks. In this study, the high-pressure behavior of an intermediate member of the scapolite solid solution series (Me47), chemical formula (Na1.86Ca1.86K0.23Fe0.01)(Al4.36Si7.64)O24[Cl0.48(CO3)0.48(SO4)0.01], has been investigated up to 17.79 GPa, by means of in situ single-crystal synchrotron X-ray diffraction. The isothermal elastic behavior of the studied scapolite has been described by a III-order Birch–Murnaghan equation of state, which provided the following refined parameters: V0 = 1110.6(7) Å3, KV0 = 70(2) GPa (βV0 = 0.0143(4) GPa−1) and KV′ = 4.8(7). The refined bulk modulus is intermediate between those previously reported for Me17 and Me68 scapolite samples, confirming that the bulk compressibility among the solid solution increases with the Na content. A discussion on the P-induced structure deformation mechanisms of tetragonal scapolite at the atomic scale is provided, along with the implications of the reported results for the modeling of scapolite stability. In addition, a single-crystal to single-crystal phase transition, which is displacive in character, has been observed toward a triclinic polymorph at 9.87 GPa. The high-pressure triclinic polymorph was found to be stable up to the highest pressure investigated.
Compressibility; Phase transition; Scapolite; Synchrotron X-ray diffraction; Materials Science (all); Geochemistry and Petrology
Settore GEO/09 - Georisorse Miner.Appl.Mineral.-Petrogr.per l'amb.e i Beni Cul
Settore GEO/06 - Mineralogia
PHYSICS AND CHEMISTRY OF MINERALS
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/603867
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