Signature of deep mantle melting in South Iceland olivine

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http://hdl.handle.net/10138/302548

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Nikkola , P , Gudfinnsson , G H , Bali , E , Ramo , O T , Fusswinkel , T & Thordarson , T 2019 , ' Signature of deep mantle melting in South Iceland olivine ' , Contributions to Mineralogy and Petrology , vol. 174 , no. 5 , 43 . https://doi.org/10.1007/s00410-019-1580-8

Title: Signature of deep mantle melting in South Iceland olivine
Author: Nikkola, Paavo; Gudfinnsson, Gudmundur H.; Bali, Eniko; Ramo, O. Tapani; Fusswinkel, Tobias; Thordarson, Thorvaldur
Contributor: University of Helsinki, Department of Geosciences and Geography
University of Helsinki, Department of Geosciences and Geography
Date: 2019-05
Language: eng
Number of pages: 19
Belongs to series: Contributions to Mineralogy and Petrology
ISSN: 0010-7999
URI: http://hdl.handle.net/10138/302548
Abstract: We present new high-precision major and trace element data on olivine macrocrysts from various volcano-tectonic settings in Iceland and use these data as a proxy for mantle mode and melting conditions. Within individual sampling sites examined (seven lavas and one tephra) olivine-dominated fractional crystallization, magma mixing and diffusive re-equilibration control observed variability in olivine composition. High-pressure fractional crystallization of clinopyroxene may have lowered Ca and increased Fe/Mn in one olivine population and subsolidus diffusion of Ni and Fe-Mg affected the mantle-derived Ni/Fo ratio in some compositionally zoned olivine macrocrysts. Interestingly, magmas erupted at the southern tip of the Eastern Volcanic Zone (SEVZ), South Iceland, have olivines with elevated Ni and low Mn and Ca contents compared to olivines from elsewhere in Iceland, and some of the SEVZ olivines have relatively low Sc and V and high Cr, Ti, Zn, Cu and Li in comparison to depleted Iceland rift tholeiite. In these olivines, the high Ni and low Mn indicate relatively deep melting (P-final>1.4GPa,similar to 45km), Sc, Ti and V are compatible with low-degree melts of lherzolite mantle, and elevated Zn may suggest modal (low-olivine) or geochemical (high Zn) enrichment in the source. The SEVZ olivine macrocrysts probably crystallized from magmas derived from olivine-bearing but relatively deep, enriched and fertile parts of the sub-Icelandic mantle, and indicate swift ascent of magma through the SEVZ lithosphere.
Subject: Olivine
Trace elements
Mantle heterogeneity
Mantle melting
Iceland
HEIMAEY VOLCANIC CENTER
TRACE-ELEMENT
RECYCLED CRUST
OXIDATION-STATE
PLUME
PERIDOTITE
VARIABILITY
TEMPERATURE
HAWAIIAN
BASALTS
1172 Environmental sciences
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