Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle

Abstract

Research Article| November 01, 2012 Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle A. Giuliani; A. Giuliani 1School of Earth Sciences, University of Melbourne, Parkville, 3010 Victoria, Australia Search for other works by this author on: GSW Google Scholar V.S. Kamenetsky; V.S. Kamenetsky 2ARC Centre of Excellence on Ore Deposits, and School of Earth Sciences, University of Tasmania, Hobart, 7001 Tasmania, Australia Search for other works by this author on: GSW Google Scholar D. Phillips; D. Phillips 1School of Earth Sciences, University of Melbourne, Parkville, 3010 Victoria, Australia Search for other works by this author on: GSW Google Scholar M.A. Kendrick; M.A. Kendrick 1School of Earth Sciences, University of Melbourne, Parkville, 3010 Victoria, Australia3Wyatt Geological Consulting Ltd, 1/3 Westbury Grove, East St. Kilda, 3183 Victoria, Australia Search for other works by this author on: GSW Google Scholar B.A. Wyatt; B.A. Wyatt 3Wyatt Geological Consulting Ltd, 1/3 Westbury Grove, East St. Kilda, 3183 Victoria, Australia Search for other works by this author on: GSW Google Scholar K. Goemann K. Goemann 4Central Science Laboratory, University of Tasmania, Hobart, 7001 Tasmania, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information A. Giuliani 1School of Earth Sciences, University of Melbourne, Parkville, 3010 Victoria, Australia V.S. Kamenetsky 2ARC Centre of Excellence on Ore Deposits, and School of Earth Sciences, University of Tasmania, Hobart, 7001 Tasmania, Australia D. Phillips 1School of Earth Sciences, University of Melbourne, Parkville, 3010 Victoria, Australia M.A. Kendrick 1School of Earth Sciences, University of Melbourne, Parkville, 3010 Victoria, Australia3Wyatt Geological Consulting Ltd, 1/3 Westbury Grove, East St. Kilda, 3183 Victoria, Australia B.A. Wyatt 3Wyatt Geological Consulting Ltd, 1/3 Westbury Grove, East St. Kilda, 3183 Victoria, Australia K. Goemann 4Central Science Laboratory, University of Tasmania, Hobart, 7001 Tasmania, Australia Publisher: Geological Society of America Received: 18 Jan 2012 Revision Received: 16 Apr 2012 Accepted: 23 Jun 2012 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2012 Geological Society of America Geology (2012) 40 (11): 967–970. https://doi.org/10.1130/G33221.1 Article history Received: 18 Jan 2012 Revision Received: 16 Apr 2012 Accepted: 23 Jun 2012 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation A. Giuliani, V.S. Kamenetsky, D. Phillips, M.A. Kendrick, B.A. Wyatt, K. Goemann; Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle. Geology 2012;; 40 (11): 967–970. doi: https://doi.org/10.1130/G33221.1 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 Mantle xenoliths sampled by kimberlite and alkali basalt magmas show a range of metasomatic styles, but direct evidence for the nature of the metasomatising fluids is often elusive. It has been suggested that carbonate-rich melts produced by partial melting of carbonated peridotites and eclogites play an important role in modifying the composition of the lithospheric mantle. These mantle-derived carbonate melts are often inferred to be enriched in alkali elements; however, alkali-rich carbonate fluids have only been reported as micro-inclusions in diamonds and as unique melts involved in the formation of the Udachnaya-East kimberlite (Yakutia, Russia). In this paper we present the first direct evidence for alkali-carbonate melts in the shallow lithospheric mantle (∼110–115 km), above the diamond stability field. These alkali-carbonate melts are preserved in primary multiphase inclusions hosted by large metasomatic ilmenite grains contained in a polymict mantle xenolith from the Bultfontein kimberlite (Kimberley, South Africa). The inclusions host abundant carbonates (magnesite, dolomite, and K-Na-Ca carbonates), kalsilite, phlogopite, K-Na titanates, and phosphates, with lesser amounts of olivine, chlorides, and alkali sulfates. Textural and chemical observations indicate that the alkali-carbonate melt likely derived from primary or precursor kimberlite magmas. Our findings extend the evidence for alkali-carbonate melts/fluids permeating the Earth mantle outside the diamond stability field and provide new insights into the chemical features of previously hypothesized melts. As metasomatism by alkali-rich carbonate melts is often reported to affect mantle xenoliths, and predicted from experimental studies, the fluid type documented here likely represent a major metasomatising agent in the Earth’s lithospheric mantle. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.