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Hot mantle geotherms stabilize calcic carbonatite magmas up to the surface

2014; Geological Society of America; Volume: 42; Issue: 10 Linguagem: Inglês

10.1130/g35778.1

1943-2682

Tahar Hammouda, Julien Chantel, Geeth Manthilake, Jérémy Guignard, Wilson A. Crichton,

Geological and Geophysical Studies Worldwide

Research Article| October 01, 2014 Hot mantle geotherms stabilize calcic carbonatite magmas up to the surface Tahar Hammouda; Tahar Hammouda * 1Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France2Laboratoire Magmas et Volcans, CNRS, UMR 6524, F-63038 Clermont-Ferrand, France3Institut de Recherche pour le Développement, R 163, Laboratoire Magmas et Volcans, F-63038 Clermont-Ferrand, France *E-mail: t.hammouda@opgc.univ-bpclermont.fr. Search for other works by this author on: GSW Google Scholar Julien Chantel; Julien Chantel 1Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France2Laboratoire Magmas et Volcans, CNRS, UMR 6524, F-63038 Clermont-Ferrand, France3Institut de Recherche pour le Développement, R 163, Laboratoire Magmas et Volcans, F-63038 Clermont-Ferrand, France Search for other works by this author on: GSW Google Scholar Geeth Manthilake; Geeth Manthilake 1Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France2Laboratoire Magmas et Volcans, CNRS, UMR 6524, F-63038 Clermont-Ferrand, France3Institut de Recherche pour le Développement, R 163, Laboratoire Magmas et Volcans, F-63038 Clermont-Ferrand, France Search for other works by this author on: GSW Google Scholar Jérémy Guignard; Jérémy Guignard 4European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble, France Search for other works by this author on: GSW Google Scholar Wilson Crichton Wilson Crichton 4European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble, France Search for other works by this author on: GSW Google Scholar Author and Article Information Tahar Hammouda * 1Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France2Laboratoire Magmas et Volcans, CNRS, UMR 6524, F-63038 Clermont-Ferrand, France3Institut de Recherche pour le Développement, R 163, Laboratoire Magmas et Volcans, F-63038 Clermont-Ferrand, France Julien Chantel 1Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France2Laboratoire Magmas et Volcans, CNRS, UMR 6524, F-63038 Clermont-Ferrand, France3Institut de Recherche pour le Développement, R 163, Laboratoire Magmas et Volcans, F-63038 Clermont-Ferrand, France Geeth Manthilake 1Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, BP 10448, F-63000 Clermont-Ferrand, France2Laboratoire Magmas et Volcans, CNRS, UMR 6524, F-63038 Clermont-Ferrand, France3Institut de Recherche pour le Développement, R 163, Laboratoire Magmas et Volcans, F-63038 Clermont-Ferrand, France Jérémy Guignard 4European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble, France Wilson Crichton 4European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble, France *E-mail: t.hammouda@opgc.univ-bpclermont.fr. Publisher: Geological Society of America Received: 15 Apr 2014 Revision Received: 31 Jul 2014 Accepted: 04 Aug 2014 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2014 Geological Society of America Geology (2014) 42 (10): 911–914. https://doi.org/10.1130/G35778.1 Article history Received: 15 Apr 2014 Revision Received: 31 Jul 2014 Accepted: 04 Aug 2014 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Tahar Hammouda, Julien Chantel, Geeth Manthilake, Jérémy Guignard, Wilson Crichton; Hot mantle geotherms stabilize calcic carbonatite magmas up to the surface. Geology 2014;; 42 (10): 911–914. doi: https://doi.org/10.1130/G35778.1 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 The eruption of calciocarbonatites at Earth's surface is at odds with them being equilibrated with the mantle at depth because high-pressure experimental studies predict that significant magnesium contents should be expected. Here we report on new high-pressure experiments that demonstrate extreme calcium enrichment of carbonatites en route to the surface. We have monitored the decompression of partially molten carbonated peridotite using a multianvil apparatus coupled to synchrotron radiation. The experimental charge was molten at high pressure and high temperature, before being decompressed along a path that avoided the so-called "carbonate ledge" (a boundary that prevents carbonatitic melts from reaching the surface). Reaction with clinopyroxene yields calcium enrichment and magnesium depletion. The resulting Ca/(Ca + Mg) of the quenched melt reaches 0.95, which compares well with the composition of erupted calcic carbonatites [Ca/(Ca + Mg) ∼0.96–0.99] and of calcic melts trapped in mantle xenoliths from ocean islands [Ca/(Ca + Mg) ∼0.84–0.97]. Our results demonstrate that it is possible to bring carbonatites very close to the surface, without breakdown, and therefore without catastrophic CO2 release. Such occurrence appears to be favored by hot geotherms, meaning that higher temperatures tend to stabilize carbonatitic melts at shallow mantle pressure. Carbonatitic magmas are usually associated with low temperatures, because of the assumed low melting degree or low eruption temperature of the only active carbonatite volcano (i.e., Oldoinyo Lengai, Tanzania). Here we show that emplacement of carbonatites at or near the surface necessitates a hot environment. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.