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Subducted lithosphere controls halogen enrichments in the Iceland mantle plume source

Saemundur A. Halldorsson, Jaime D. Barnes, Andri Stefansson, David R. Hilton, Erik H. Hauri and Edward W. Marshall
Subducted lithosphere controls halogen enrichments in the Iceland mantle plume source
Geology (Boulder) (August 2016) 44 (8): 679-682

Abstract

The chlorine isotope composition of Earth's interior can place strong constraints on deep-Earth cycling of halogens and the origin of mantle chemical heterogeneity. However, all mantle-derived volcanic samples studied for Cl isotopes thus far originate from submarine volcanic systems, where the influence of seawater-derived Cl is pervasive. Here, we present Cl isotope data from subglacial volcanic glasses from Iceland, where the mid-ocean ridge system emerges above sea level and is free of seawater influence. The Iceland data display significant variability in delta (super 37) Cl values, from -1.8 ppm to +1.4 ppm, and are devoid of regional controls. The absence of correlations between Cl and O isotope ratios and the lack of evidence for seawater-derived enrichments in Cl indicate that the variation in delta (super 37) Cl values in Icelandic basalts can be solely attributed to mantle heterogeneity. Indeed, positive correlations are evident between delta (super 37) Cl values and incompatible trace element ratios (e.g., La/Y), and long-lived radiogenic Pb isotope ratios. The data are consistent with the incorporation of altered lithosphere, including the uppermost sedimentary package, subducted into the Iceland mantle plume source, resulting in notable halogen enrichments in Icelandic basalts relative to lavas from adjacent mid-ocean ridges.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 44
Serial Issue: 8
Title: Subducted lithosphere controls halogen enrichments in the Iceland mantle plume source
Affiliation: University of Iceland, Institute of Earth Sciences, Reykjavik, Iceland
Pages: 679-682
Published: 201608
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 34
Accession Number: 2016-069351
Categories: Isotope geochemistrySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016222
Illustration Description: illus.
N63°40'00" - N66°30'00", W24°45'00" - W13°30'00"
Secondary Affiliation: University of Texas at Austin, USA, United StatesUniversity of California at San Diego, USA, United StatesCarnegie Institution of Washington, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201633
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