Disequilibrium in historic volcanic rocks from Fogo, Cape Verde traces carbonatite metasomatism of recycled ocean crust

Barker, AbigailUppsala universitet,Mineralogi, petrologi och tektonik,Centre of Natural Hazards and Disaster Sciences (CNDS), Uppsala, Sweden (författare)

Fogo, Cape Verde, located upon thick oceanic lithosphere, provides a window into processes occurring in the mantle where recycled ocean crust in an upwelling mantle plume interacts with ambient mantle. Our objective is to investigate the nature of the lithologies of the mantle sources involved in the petrogenesis of historic volcanic rocks from Fogo. We observe enclaves and mingling textures in the lavas combined with oxygen isotope disequilibrium between olivine and clinopyroxene phenocrysts. Olivine δ18O values display positive correlations with Zr/Hf and Zr/Y and a negative correlation with U/Th, whereas clinopyroxene δ 18O values correlate positively with Ba/Nb. Heterogeneity between crystal populations and within the groundmass indicates that multiple magma batches are mixed beneath Fogo. In terms of mantle endmembers and source lithologies, a HIMU endmember was generated by melting of carbonated eclogite as indicated by low δ 18O values, Zr/Hf, Ba/Nb and high U/Th ratios. In contrast, we show the EM1 endmember has high δ 18O, Zr/Hf, Ba/Nb and low U/Th ratios, derived from melting of variably carbonated peridotite. Additionally, Ba/Th ratio are high, indicating that carbonatite melts have contributed to alkaline magma compositions at Fogo.

Magnusson, E.Uppsala universitet,Institutionen för geovetenskaper (författare)
Troll, Valentin R.Uppsala universitet,Naturresurser och hållbar utveckling,Centre of Natural Hazards and Disaster Sciences (CNDS), Uppsala, Sweden;Instituto de Estudios Ambientales y Recursos Naturales (iUNAT), Universidad de Las Palmas de Gran Canaria (ULPGC), Las Palmas de Gran Canaria 35017, Spain(Swepub:uu)valtr808 (författare)
Harris, C. (författare)
Mattsson, Hannes B.Uppsala universitet,Mineralogi, petrologi och tektonik,Institute for Mineralogy and Petrology, ETH Zürich, Switzerland(Swepub:uu)hanma332 (författare)
Holm, P.M. (författare)
Perez-Torrado, F.J. (författare)
Carracedo, J.C. (författare)
Deegan, FrancesUppsala universitet,Naturresurser och hållbar utveckling,Centre of Natural Hazards and Disaster Sciences (CNDS), Uppsala, Sweden(Swepub:uu)frade877 (författare)
Uppsala universitetMineralogi, petrologi och tektonik (creator_code:org_t)

Av författaren/redakt...: Barker, Abigail; Magnusson, E.; Troll, Valentin ...; Harris, C.; Mattsson, Hannes ...; Holm, P.M.; visa fler...; Perez-Torrado, F ...; Carracedo, J.C.; Deegan, Frances; visa färre...

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