Crystallisation temperatures of the most Mg-rich magmas of the Karoo LIP on the basis of Al-in-olivine thermometry

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dc.contributor.author Heinonen, Jussi S.
dc.contributor.author Jennings, Eleanor S.
dc.contributor.author Riley, Teal R.
dc.date.accessioned 2015-08-21T11:54:01Z
dc.date.available 2015-08-21T11:54:01Z
dc.date.issued 2015-09-14
dc.identifier.citation Heinonen , J S , Jennings , E S & Riley , T R 2015 , ' Crystallisation temperatures of the most Mg-rich magmas of the Karoo LIP on the basis of Al-in-olivine thermometry ' , Chemical Geology , vol. 411 , pp. 26-35 . https://doi.org/10.1016/j.chemgeo.2015.06.015
dc.identifier.other PURE: 49961129
dc.identifier.other PURE UUID: 91701266-34c9-43d8-8a6d-af2d6e01a2b1
dc.identifier.other WOS: 000360018300004
dc.identifier.other Scopus: 84936747960
dc.identifier.uri http://hdl.handle.net/10138/156273
dc.description.abstract Calculating reliable temperatures of Mg-rich magmas is problematic because melt composition and KD(Fe-Mg)ol-liq, the key parameters of many traditional thermometers, are difficult to constrain precisely. The recently developed Al-in-olivine thermometer [Coogan, L.A., Saunders, A.D., Wilson, R.N., 2014. Aluminum-in-olivine thermometry of primitive basalts: Evidence of an anomalously hot mantle source for large igneous provinces. Chemical Geology 368, 1–10] circumvents these problems by relying on the temperature-dependent exchange of Al between olivine and spinel crystallising in equilibrium with each other. This thermometer is used to re-evaluate the crystallisation temperatures of the most Mg-rich magma type identified from the Karoo large igneous province (LIP), known as the Vestfjella depleted ferropicrite suite. Previous temperature estimates for the suite were based on olivine-melt equilibria and indicated anomalously high crystallisation temperatures in excess of 1600 °C. We also present crystallisation temperatures for another Antarctic Karoo magma type, Group 3 dykes from Ahlmannryggen, which are derived from a pyroxene-rich mantle source. Our high-precision analysis of Al in olivine-spinel pairs indicate crystallisation temperatures from 1391±42 °C to 1481±35 °C for the Vestfjella depleted ferropicrite suite (Fo88–92) and from 1253±64 °C to 1303±40 °C for the Group 3 dykes (Fo79–82). Although the maximum temperature estimates for the former are over 100 °C lower than the previously presented estimates, they are still ~200 °C higher than those calculated for mid-ocean ridge basalts using the same method. Although exact mantle potential temperatures are difficult to estimate, the presented results support elevated sub-Gondwanan upper mantle temperatures (generated by a mantle plume or internal mantle heating) during the generation of the Karoo LIP. fi
dc.description.abstract Calculating reliable temperatures of Mg-rich magmas is problematic because melt composition and KD(Fe-Mg)ol-liq, the key parameters of many traditional thermometers, are difficult to constrain precisely. The recently developed Al-in-olivine thermometer [Coogan, L.A., Saunders, A.D., Wilson, R.N., 2014. Aluminum-in-olivine thermometry of primitive basalts: Evidence of an anomalously hot mantle source for large igneous provinces. Chemical Geology 368, 1–10] circumvents these problems by relying on the temperature-dependent exchange of Al between olivine and spinel crystallising in equilibrium with each other. This thermometer is used to re-evaluate the crystallisation temperatures of the most Mg-rich magma type identified from the Karoo large igneous province (LIP), known as the Vestfjella depleted ferropicrite suite. Previous temperature estimates for the suite were based on olivine-melt equilibria and indicated anomalously high crystallisation temperatures in excess of 1600 °C. We also present crystallisation temperatures for another Antarctic Karoo magma type, Group 3 dykes from Ahlmannryggen, which are derived from a pyroxene-rich mantle source. Our high-precision analysis of Al in olivine-spinel pairs indicate crystallisation temperatures from 1391±42 °C to 1481±35 °C for the Vestfjella depleted ferropicrite suite (Fo88–92) and from 1253±64 °C to 1303±40 °C for the Group 3 dykes (Fo79–82). Although the maximum temperature estimates for the former are over 100 °C lower than the previously presented estimates, they are still ~200 °C higher than those calculated for mid-ocean ridge basalts using the same method. Although exact mantle potential temperatures are difficult to estimate, the presented results support elevated sub-Gondwanan upper mantle temperatures (generated by a mantle plume or internal mantle heating) during the generation of the Karoo LIP. en
dc.format.extent 10
dc.language.iso eng
dc.relation.ispartof Chemical Geology
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject 119 Other natural sciences
dc.subject Karoo magmatism
dc.subject LARGE IGNEOUS PROVINCE
dc.subject CONTINENTAL FLOOD BASALTS
dc.subject picrite
dc.subject THERMOMETRY
dc.title Crystallisation temperatures of the most Mg-rich magmas of the Karoo LIP on the basis of Al-in-olivine thermometry en
dc.title.alternative Karoon suuren magmaprovinssin Mg-rikkaimpien magmojen kiteytymislämpötilat Al-oliviini termometrin perusteella fi
dc.type Article
dc.contributor.organization Finnish Museum of Natural History
dc.contributor.organization Natural Sciences Unit
dc.description.reviewstatus Peer reviewed
dc.relation.doi https://doi.org/10.1016/j.chemgeo.2015.06.015
dc.relation.issn 0009-2541
dc.rights.accesslevel openAccess
dc.type.version acceptedVersion
dc.identifier.url http://www.sciencedirect.com/science/article/pii/S0009254115003034

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