Lithium isotopic composition of Central American volcanic arc lavas: implications for modification of subarc mantle by slab-derived fluids: correction |
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| Institution: | 1. CODES and Earth Sciences, University of Tasmania, Hobart, TAS 7001, Australia;2. Institute of Experimental Mineralogy RAS, Chernogolovka 142432, Russia;3. Centre de Recherches Pétrographiques et Géochimiques (CRPG), UMR 7358, Université de Lorraine, 54501 Vandoeuvre-lès-Nancy, France;4. GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany;5. V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, 119991 Moscow, Russia;6. BHP Billiton Olympic Dam, Adelaide, SA 5000, Australia;7. Institute of Volcanology and Seismology, Far East Branch, Russian Academy of Sciences, 683006 Petropavlovsk-Kamchatsky, Russia;8. Central Science Laboratory, University of Tasmania, Hobart, TAS 7001, Australia;1. ARC Centre of Excellence for Core to Crust Fluid Systems/GEMOC, Department of Earth and Planetary Sciences, Macquarie University, Sydney NSW 2109, Australia;2. GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 5, 91054 Erlangen, Germany;3. Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan;4. Istituto di Geoscienze e Georisorse-CNR, Via Moruzzi 1, Pisa, Italy;1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, PR China;2. Isotope Laboratory, Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA;3. School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 10083, PR China;4. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, PR China;5. Roosevelt High School, Seattle, WA 98115, USA;6. Jiangxi Provincial Institute of Geological Survey, Nanchang 330030, PR China |
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| Abstract: | Our previously reported lithium isotope data for the least enriched members of the Central American Volcanic Arc were in error due to problems in ion extraction from high MgO rocks. This paper presents reanalyses of the entire suite of the CAVA lavas after a systematic investigation of the elution behavior of Li as a function of the rock composition. The most significant correction pertains to the mantle end members of the Nicaragua and Costa Rica series, which now display MORB-like δ6Li values (−4.5‰) and not much lighter (+1‰ to +3‰) as previously reported. Also revised is the composition of a peridotite from Zabargad Island (Red Sea), considered to represent undepleted upper mantle, whose corrected δ6Li also resembles MORB. These new data therefore remove the speculation that Earth's primitive mantle has extremely light Li isotopic composition and that the mantle beneath CAVA contains such isotopically light domains. The δ6Li range for the arc segment from Costa Rica to Guatemala has now been reset to −4.5‰ to −6.4‰. Despite the narrower range, Li isotopic values remain well correlated with other subduction-related properties, including LILE and fluid-mobile elements. Model calculations show that the isotopic compositions of the lavas are consistent with small additions of slab-derived fluids to the enriched and depleted domains of the subarc mantle. |
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