Seismic properties of the supra-subduction mantle: Constraints from peridotite xenoliths from the Avacha volcano, southern Kamchatka

• Published in: Geophysical Research Letters
• Main Authors: Soustelle, Vincent, Tommasi, Andrea
• Other Authors: Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: seismic properties; xenolith; subduction; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; [SDE.MCG]Environmental Sciences/Global Changes; Avacha; Kamchatka
• Online Access: https://hal.science/hal-00512636; https://hal.science/hal-00512636/document; https://hal.science/hal-00512636/file/2010GL043450.pdf; https://doi.org/10.1029/2010GL043450

International audience This work presents seismic properties derived from a detailed microstructural study of supra-subduction mantle xenoliths extracted by the active Avacha volcano in the southern Kamchatka arc. These peridotites underwent low-stress deformation and syn- to late-kinematic reactive percolation of hydrous melts or fluids leading to local orthopyroxene enrichment and dispersion of the olivine CPO in the shallow mantle wedge. All samples show an axial [ 100] olivine CPO implying fast S-wave polarization parallel to the flow direction in the mantle. Orthopyroxene-enrichment by reactive fluids/melts percolation lowers the Vp/Vs ratio, but cannot explain the Vp/Vs ratios <1.7 mapped in the Japan and Andes forearc mantle. These low Vp/Vs ratios may however be explained by considering the intrinsic anisotropy of the peridotites.