Repository logo
 

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

Published version
Peer-reviewed

Change log

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 1480−30+37 °C for Iceland and 1318−32+44 °C for MORB.

Description

Keywords

37 Earth Sciences, 3703 Geochemistry, 3705 Geology, 3706 Geophysics

Journal Title

Geochemistry, Geophysics, Geosystems

Conference Name

Journal ISSN

1525-2027
1525-2027

Volume Title

17

Publisher

Wiley
Sponsorship
NERC (via University of Oxford) (NE/M000427/1 - DGR00210)
Natural Environment Research Council (NE/J021539/1)
NERC (NE/L002507/1)
NERC (NE/L002507/1)
O.S. was supported by a Title A Fellowship from Trinity College Cambridge and a Geology Option Postdoctoral Fellowship at Caltech.