Mixed pyroxenite–peridotite sources for mafic and ultramafic dikes from the Antarctic segment of the Karoo continental flood basalt province

Heinonen, Jussi S.; Luttinen, Arto V.; Riley, Teal R.; Michallik, Radoslaw M.

doi:10.1016/j.lithos.2013.05.015

Cited by 46 publications

(37 citation statements)

References 75 publications

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“…The overall compositional characteristics of the phases are similar to previous analytical studies Heinonen et al, 2013) with the exception that MnO was not previously measured from the depleted ferropicrite suite spinels . In addition, our new data does not include the rare Fo 89-90 olivine phenocrysts identified in Group 3 sample Z1816.3 (Heinonen et al, 2013).…”

Section: Resultssupporting

confidence: 81%

“…In addition, our new data does not include the rare Fo 89-90 olivine phenocrysts identified in Group 3 sample Z1816.3 (Heinonen et al, 2013).…”

Section: Resultsmentioning

confidence: 99%

“…Four intrusive magma types from western Dronning Maud Land show evidence of limited lithospheric interaction and derivation of the parental magmas from sublithospheric sources: 1) The Vestfjella depleted ferropicrite suite, 2) Vestfjella Low-Nb dykes, 3) The Vestfjella enriched ferropicrite suite, and 4) Ahlmannryggen Group 3 dykes (Riley et al, 2005;Heinonen and Luttinen, 2008;Luttinen et al, 2015). The first two originated from a common depleted (upper mantle) source Luttinen et al, 2015) and the latter two derive from distinct pyroxene-rich (recycled) mantle sources (Heinonen et al, , 2013(Heinonen et al, , 2014. In this study, we will concentrate on the depleted ferropicrite suite and Group 3 dykes.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…1; Riley et al, 2005). In addition to fresh olivine and clinopyroxene phenocrysts, many of the Group 3 dykes also contain orthopyroxene phenocrysts, which indicate high pressures of crystallisation and pyroxene-rich mantle sources (Heinonen et al, 2013). Picritic samples Z1813.1, Z1817.2, and Z1816.3, with fresh euhedral olivine and euhedral/subhedral spinel inclusions (Fig.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…3 samples show evidence of a variable degree of olivine and orthopyroxene accumulation (Heinonen et al, 2013).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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

2015

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Calculating reliable temperatures of Mg-rich magmas is problematic because melt composition and K D (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 reevaluate 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 ) and from 1253±64 °C to 1303±40 °C for the Group 3 dykes ). 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.

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Section: Resultssupporting

confidence: 81%

“…In addition, our new data does not include the rare Fo 89-90 olivine phenocrysts identified in Group 3 sample Z1816.3 (Heinonen et al, 2013).…”

Section: Resultsmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…3 samples show evidence of a variable degree of olivine and orthopyroxene accumulation (Heinonen et al, 2013).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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

2015

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Enrichment of 18O in the mantle sources of the Antarctic portion of the Karoo large igneous province

Heinonen

Luttinen

Whitehouse

2018

Contrib Mineral Petrol

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Karoo continental flood basalt (CFB) province is known for its highly variable trace element and isotopic composition, often attributed to the involvement of continental lithospheric sources. Here we report oxygen isotopic compositions measured with secondary ion mass spectrometry for handpicked olivine phenocrysts from ~190-180 Ma CFBs and intrusive rocks from Vestfjella, western Dronning Maud Land, that forms an Antarctic extension of the Karoo province. The Vestfjella lavas exhibit heterogeneous trace element and radiogenic isotope compositions (e.g., εNd from-16 to +2 at 180 Ma) and the involvement of continental lithospheric mantle and/or crust in their petrogenesis has previously been suggested. Importantly, our sample set also includes rare primitive dikes that have been derived from depleted asthenospheric mantle sources (εNd up to +8 at 180 Ma). The majority of the oxygen isotopic compositions of the olivines from these dike rocks (δ 18 O = 4.4-5.2 ‰; Fo = 78-92 mol. %) are also compatible with such sources. The olivine phenocrysts in the lavas, however, are characterized by notably higher δ 18 O (6.2-7.5 ‰; Fo = 70-88 mol. %) and one of the dike samples gives intermediate compositions (5.2-6.1 ‰, Fo = 83-87 mol. %) between the other dikes and the CFBs. The oxygen isotopic compositions do not correlate with radiogenic isotope compositions susceptible to crustal assimilation (Sr, Nd, and Pb) or with geochemical indicators of pyroxene-rich mantle sources. Instead, δ 18 O correlates positively with enrichments in large-ion lithophile elements (especially K) and 187 Os. We suggest that the oxygen isotopic compositions of the Vestfjella CFB olivines primarily record large-scale subduction-related metasomatism of the sub-Gondwanan mantle (base of the lithosphere or deeper) prior to Karoo magmatism. The overall influence of such sources to Karoo magmatism is not known, but, in addition to continental lithosphere, they may be responsible for some of the geochemical heterogeneity observed in the CFBs.

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Windowing petrogenesis of continental flood basalts through mineralogical investigations: a case study from the Eastern Deccan Volcanic Province

Dey

Ray

Sheikh

et al. 2021

Int J Earth Sci (Geol Rundsch)

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Mixed pyroxenite–peridotite sources for mafic and ultramafic dikes from the Antarctic segment of the Karoo continental flood basalt province

Cited by 46 publications

References 75 publications

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

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

Enrichment of 18O in the mantle sources of the Antarctic portion of the Karoo large igneous province

Windowing petrogenesis of continental flood basalts through mineralogical investigations: a case study from the Eastern Deccan Volcanic Province

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