TY - JOUR

T1 - In situ X-ray diffraction study of chrysotile at high P–T conditions: transformation to the 3.65 Å phase

AU - Goryainov, Sergey V.

AU - Tse, John S.

AU - Desgreniers, Serge

AU - Kawaguchi, Saori I.

AU - Pan, Yuanming

AU - Likhacheva, Anna Yu

AU - Molokeev, Maxim S.

N1 - Funding Information: This work was performed under the auspicious of the state assignment of IGM SB RAS supported by Ministry of Science and Higher Education of the Russian Federation. The Russian Foundation for Basic Research (project no.21-55-14001) is gratefully acknowledged. Authors thank S.V. Rashchenko for fruitful discussion on XRD diffraction patterns of the talc-water system. We thank SPring-8 Synchrotron Radiation Facilities and BLXU-10 beamline for providing the synchrotron beam-time. JST, SD and YP would like to thank Natural Science and Engineering Council Canada for the award of individual Discovery Grants. Publisher Copyright: © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

PY - 2021/10

Y1 - 2021/10

N2 - The behavior of chrysotile Mg3(Si2O5)(OH)4 in water medium at simultaneously high pressure and high temperature was studied by in situ synchrotron X-ray diffraction using a diamond anvil cell. In contrast to previous ‘dry’ experiments, chrysotile in water-saturated conditions undergoes two-phase transitions and exhibits higher thermal stability. At 260 °C / 3.7 GPa the initial chrysotile (phase I) transforms to the ‘chrysotile-like’ phase II, followed by the appearance of the ‘chrysotile-like’ phase III at 405 °C / 5.25 GPa. Phase III is characterized by enlarged interlayer distances, presumably resulting from the H2O intercalation into the interlayer space. During further compression, the ‘chrysotile-like’ phase III is decomposed to the 10 Å phase Mg3(Si4O10)(OH)2·xH2O, the 3.65 Å phase MgSi(OH)6, phase D, forsterite, enstatite and coesite or stishovite. The 3.65 Å phase appears at 8.8 GPa / 500 °C. The series of transformations leads to a water deficiency in the system, restricting the complete transformation from the 10 Å phase to the 3.65 Å phase. These data emphasize the crucial role of excess water in the stabilization of the high-pressure hydrous phases. The present study is the first in situ observation of sequential transformations of hydrous phases: serpentine → 10 Å phase → 3.65 Å phase, important as a potential water transport mechanism to the deep mantle.

AB - The behavior of chrysotile Mg3(Si2O5)(OH)4 in water medium at simultaneously high pressure and high temperature was studied by in situ synchrotron X-ray diffraction using a diamond anvil cell. In contrast to previous ‘dry’ experiments, chrysotile in water-saturated conditions undergoes two-phase transitions and exhibits higher thermal stability. At 260 °C / 3.7 GPa the initial chrysotile (phase I) transforms to the ‘chrysotile-like’ phase II, followed by the appearance of the ‘chrysotile-like’ phase III at 405 °C / 5.25 GPa. Phase III is characterized by enlarged interlayer distances, presumably resulting from the H2O intercalation into the interlayer space. During further compression, the ‘chrysotile-like’ phase III is decomposed to the 10 Å phase Mg3(Si4O10)(OH)2·xH2O, the 3.65 Å phase MgSi(OH)6, phase D, forsterite, enstatite and coesite or stishovite. The 3.65 Å phase appears at 8.8 GPa / 500 °C. The series of transformations leads to a water deficiency in the system, restricting the complete transformation from the 10 Å phase to the 3.65 Å phase. These data emphasize the crucial role of excess water in the stabilization of the high-pressure hydrous phases. The present study is the first in situ observation of sequential transformations of hydrous phases: serpentine → 10 Å phase → 3.65 Å phase, important as a potential water transport mechanism to the deep mantle.

KW - Chrysotile

KW - High pressure

KW - High temperature

KW - Serpentine

KW - Synchrotron radiation

KW - X-ray diffraction

UR - http://www.scopus.com/inward/record.url?scp=85116134359&partnerID=8YFLogxK

U2 - 10.1007/s00269-021-01160-8

DO - 10.1007/s00269-021-01160-8

M3 - Article

AN - SCOPUS:85116134359

VL - 48

JO - Physics and Chemistry of Minerals

JF - Physics and Chemistry of Minerals

SN - 0342-1791

IS - 10

M1 - 36

ER -