Abstract

Research Article| June 01, 2003 Alkalic magmas generated by partial melting of garnet pyroxenite Marc M. Hirschmann; Marc M. Hirschmann 1Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA, and Division of Geological and Planetary Science, 170-25, California Institute of Technology, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar Tetsu Kogiso; Tetsu Kogiso 2Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA Search for other works by this author on: GSW Google Scholar Michael B. Baker; Michael B. Baker 3 Division of Geological and Planetary Sciences, 170-25, California Institute of Technology, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar Edward M. Stolper Edward M. Stolper 3 Division of Geological and Planetary Sciences, 170-25, California Institute of Technology, Pasadena, California 91125, USA Search for other works by this author on: GSW Google Scholar Geology (2003) 31 (6): 481–484. https://doi.org/10.1130/0091-7613(2003)0312.0.CO;2 Article history received: 17 Oct 2002 rev-recd: 05 Mar 2003 accepted: 07 Mar 2003 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Marc M. Hirschmann, Tetsu Kogiso, Michael B. Baker, Edward M. Stolper; Alkalic magmas generated by partial melting of garnet pyroxenite. Geology 2003;; 31 (6): 481–484. doi: https://doi.org/10.1130/0091-7613(2003)0312.0.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 Many oceanic-island basalts (OIBs) with isotopic signatures of recycled crustal components are silica poor and strongly nepheline (ne) normative and therefore unlike the silicic liquids generated from partial melting of recycled mid-oceanic-ridge basalt (MORB). High-pressure partial-melting experiments on a garnet pyroxenite (MIX1G) at 2.0 and 2.5 GPa produce strongly ne-normative and silica-poor partial melts. The MIX1G solidus is located below 1350 and 1400 °C at 2 and 2.5 GPa, respectively, slightly cooler than the solidus of dry peridotite. Chemographic analysis suggests that natural garnet pyroxenite compositions straddle a thermal divide. Whereas partial melts of compositions on the silica-excess side of the divide (such as recycled MORB) are silica saturated, those from silica-deficient garnet pyroxenites can be alkalic and have similarities to low-silica OIB. Although the experimental partial melts are too rich in Al2O3 to be parental to highly undersaturated OIB suites, higher-pressure (4–5 GPa) partial melting of garnet pyroxenite is expected to yield more appropriate parental liquids for OIB lavas. Silica-deficient garnet pyroxenite, which may originate by mixing of MORB with peridotite, or by recycling of other mafic lithologies, represents a plausible source of OIB that may resolve the apparent contradiction of strongly alkalic composition with isotopic ratios characteristic of a recycled component. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.