Metasomatism of Cascades subarc mantle: Evidence from a rare phlogopite orthopyroxenite xenolith

Research Article| May 01, 1996 Metasomatism of Cascades subarc mantle: Evidence from a rare phlogopite orthopyroxenite xenolith Inci Evren Ertan; Inci Evren Ertan 1Keith-Wiess Geological Laboratory, MS 126, Rice University, Houston, Texas 77005-1892 Search for other works by this author on: GSW Google Scholar William P. Leeman William P. Leeman 1Keith-Wiess Geological Laboratory, MS 126, Rice University, Houston, Texas 77005-1892 Search for other works by this author on: GSW Google Scholar Author and Article Information Inci Evren Ertan 1Keith-Wiess Geological Laboratory, MS 126, Rice University, Houston, Texas 77005-1892 William P. Leeman 1Keith-Wiess Geological Laboratory, MS 126, Rice University, Houston, Texas 77005-1892 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1996) 24 (5): 451–454. https://doi.org/10.1130/0091-7613(1996)024<0451:MOCSME>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Inci Evren Ertan, William P. Leeman; Metasomatism of Cascades subarc mantle: Evidence from a rare phlogopite orthopyroxenite xenolith. Geology 1996;; 24 (5): 451–454. doi: https://doi.org/10.1130/0091-7613(1996)024<0451:MOCSME>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Ultramafic xenoliths in the southern Washington Cascades lavas provide a rare view of the upper mantle beneath a convergent margin volcanic arc. An unusual olivine orthopyroxenite from this xenolith suite shows evidence of extreme multistage metasomatism involving infiltration of high-K2O silicic melts and CO2 fluid, replacement of olivine by orthopyroxene, and entrapment of fluid, melt, and phlogopite inclusions within orthopyroxene—all prior to its entrainment in the host basaltic magma. Analyses of minerals, glass, and fluid inclusions show that the mantle source of this rock was ≥30 km below the surface and reached a temperature of at least 1000 °C—possibly in response to basaltic underplating. This region of the mantle was previously enriched in silica and potassium, but not necessarily due to subduction processes. The metasomatic melts may be derived from an accreted slab of oceanic lithosphere, as opposed to a subducting oceanic plate. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.