Major element records of variable plume involvement in the North Atlantic Province tertiary flood basalts

Scarrow, J. H., Curran, J. M. and Kerr, Andrew Craig ORCID: https://orcid.org/0000-0001-5569-4730 2000. Major element records of variable plume involvement in the North Atlantic Province tertiary flood basalts. Journal of Petrology 41 (7) , pp. 1155-1176. 10.1093/petrology/41.7.1155

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Abstract

Major element variations in North Atlantic Tertiary Province primitive, early erupted, alkaline-transitional-tholeiite basalts, recalculated to a restricted value of MgO, give insights into the process of plume-related magmatism. Basalts primitive enough to be crystallizing only olivine were recalculated to a proposed primary magma composition of 15 wt % MgO. The recalculated dataset shows clear inter-element correlations including a strong, significant, negative correlation between Fe and Si indicating polybaric melt segregation. Overlap between basalt compositions and experimental melts from a fertile, Fe-rich, low mg-number (85.5) peridotite suggests that, relative to normal peridotite with mg-number > 89, the North Atlantic basalt source was Fe rich. Linear regression of the experimental data gives apparent pressures of magma segregation of 17·5–37 kbar, with intra-region variability in the depth derivation from the melt column for each sample, thus suggesting that lithospheric thickness ‘lid-effect’ control on magma generation may have been overemphasized in recent studies. Comparable source composition, magma segregation depth and calculated mantle potential temperature (1440–1460°C) throughout the Province supports the previously suggested plume impact model, arriving below East Greenland, derived from a variably enriched and depleted lower-mantle source. Given the good agreement between conclusions drawn from major element data and previously published results we suggest that restricted-MgO recalculated datasets may be usefully applied to study other large igneous provinces.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Uncontrolled Keywords:	basalt; Fe-rich mantle; large igneous provinces; North Atlantic Tertiary Province; restricted-MgO major element datasets
Publisher:	OUP
ISSN:	1460-2415
Last Modified:	18 Oct 2022 12:22
URI:	https://orca.cardiff.ac.uk/id/eprint/9589

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