Experimental study of the system phlogopite-diopside from 3.5 to 17 GPa

Other| December 01, 1997 Experimental study of the system phlogopite-diopside from 3.5 to 17 GPa Robert W. Luth Robert W. Luth University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada Search for other works by this author on: GSW Google Scholar American Mineralogist (1997) 82 (11-12): 1198–1209. https://doi.org/10.2138/am-1997-11-1216 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Robert W. Luth; Experimental study of the system phlogopite-diopside from 3.5 to 17 GPa. American Mineralogist 1997;; 82 (11-12): 1198–1209. doi: https://doi.org/10.2138/am-1997-11-1216 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract On the basis of both natural samples and experimental studies, clinopyroxene is a potential reservoir for potassium in the Earth's mantle. The amount of K partitioning into clinopyroxene depends on the phase assemblage present, the bulk composition, pressure, and temperature. To investigate some of these dependencies, subsolidus and melting phase relations in the system phlogopite-diopside have been studied to 17 GPa. In this system, phlogopite becomes unstable with increasing pressure, breaking down to potassium richterite, which in turn breaks down to another K-bearing hydrous phase (phase X), such that a K-rich phase coexists with clinopyroxene to 17 GPa. Clinopyroxenes contain ≤1.3 wt% K2O in assemblages of phlogopite + clinopyroxene ± olivine ± liquid at 3–5 GPa, phlogopite + clinopyroxene + garnet ± olivine ± liquid at 7–9 GPa, clinopyroxene + garnet + olivine ± potassium richterite ± liquid at 11 GPa, and clinopyroxene + olivine + garnet + phase X at 14 and 17 GPa.In these assemblages, K is partitioned into hydrous phases or liquid, rather than into the clinopyroxene. By inference, phlogopite (or its higher-pressure breakdown products) is the primary host for K in the mantle (if H2O is present), and any coexisting clinopyroxene has very low concentrations of K. Conversely, the natural occurrence of clinopyroxene with >> 1 wt% K2O requires that phlogopite, potassium richterite, or phase X is not stable in the local source environment of such samples. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.