The temperature of the Icelandic mantle from olivine-spinel aluminum exchange thermometry

Matthews, S. and Shorttle, O. and Maclennan, J. (2016) The temperature of the Icelandic mantle from olivine-spinel aluminum exchange thermometry. Geochemistry, Geophysics, Geosystems, 17 (11). pp. 4725-4752. ISSN 1525-2027 DOI 10.1002/2016GC006497

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Abstract

New crystallization temperatures for four eruptions from the Northern Volcanic Zone of Iceland are determined using olivine-spinel aluminum exchange thermometry. Differences in the olivine crystallization temperatures between these eruptions are consistent with variable extents of cooling during fractional crystallization. However, the crystallization temperatures for Iceland are systematically offset to higher temperatures than equivalent olivine-spinel aluminum exchange crystallization temperatures published for MORB, an effect that cannot be explained by fractional crystallization. The highest observed crystallization temperature in Iceland is 1399 ± 20°C. In order to convert crystallization temperatures to mantle potential temperature, we developed a model of multilithology mantle melting that tracks the thermal evolution of the mantle during isentropic decompression melting. With this model, we explore the controls on the temperature at which primary melts begin to crystallize, as a function of source composition and the depth from which the magmas are derived. Large differences (200°C) in crystallization temperature can be generated by variations in mantle lithology, a magma's inferred depth of origin, and its thermal history. Combining this model with independent constraints on the magma volume flux and the effect of lithological heterogeneity on melt production, restricted regions of potential temperature-lithology space can be identified as consistent with the observed crystallization temperatures. Mantle potential temperature is constrained to be math formula °C for Iceland and math formula °C for MORB.

Item Type:	Article
Uncontrolled Keywords:	2017AREP; IA72; bull
Subjects:	05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions:	05 - Petrology - Igneous, Metamorphic and Volcanic Studies 08 - Green Open Access
Journal or Publication Title:	Geochemistry, Geophysics, Geosystems
Volume:	17
Page Range:	pp. 4725-4752
Identification Number:	10.1002/2016GC006497
Depositing User:	Sarah Humbert
Date Deposited:	07 Feb 2017 14:11
Last Modified:	27 Jun 2017 09:20
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3811

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