Ultramafic lamprophyres of the Ferrar large igneous province:Evidence for a HIMU mantle component

Ultramafic lamprophyre (UML) dykes from the Ferrar Province (Pensacola Mountains) of Antarctica preserve trace element and isotope signatures similar to Bouvet volcanic rocks, which are considered to reflect the palaeo composition of the Bouvet mantle plume. We report Sr, Nd, Pb, and Os isotope comp...

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Bibliographic Details
Published in:Lithos
Main Authors: Riley, Teal R., Leat, Philip T., Storey, Bryan C., Parkinson, Ian J., Millar, Ian L.
Format: Article in Journal/Newspaper
Language:English
Published: 2003
Subjects:
Bouvet
Ferrar
Karoo
Mantle plume
Ultramafic lamprophyne
Antarc*
Antarctica
Ocean Island
Online Access:https://hdl.handle.net/1983/5b5ddba4-6336-4834-a6e7-a5a6f69fec20
https://research-information.bris.ac.uk/en/publications/5b5ddba4-6336-4834-a6e7-a5a6f69fec20
https://doi.org/10.1016/S0024-4937(02)00213-X
http://www.scopus.com/inward/record.url?scp=0037213233&partnerID=8YFLogxK
Description
Summary:Ultramafic lamprophyre (UML) dykes from the Ferrar Province (Pensacola Mountains) of Antarctica preserve trace element and isotope signatures similar to Bouvet volcanic rocks, which are considered to reflect the palaeo composition of the Bouvet mantle plume. We report Sr, Nd, Pb, and Os isotope compositions for three ultramafic lamprophyre dykes emplaced at 183.2±2.2 Ma, coincident with the main Karoo-Ferrar magmatic event. The ultramafic lamprophyre dykes are characterized by high Ti, Cr, Ni, Nb/La, La N /Yb N , and Mg# values, and are the most primitive rocks of the Ferrar Province. The dykes have initial (183 Ma) 87 Sr/ 86 Sr ratios of 0.7044-0.7055, εNd of 4.6-4.8, 208 Pb/ 204 Pb of 39.6-40.3, and 187 Os/ 188 Os of 0.120-0.146 and contrast markedly with even the most primitive rocks of the Ferrar and Karoo provinces. The trace element and isotope characteristics have affinities to ocean island basalt (OIB) and the highly radiogenic character of 208 Pb/ 204 Pb and 206 Pb/ 204 Pb bear closest resemblance to Bouvet, which has previously been postulated as the plume responsible for the Ferrar Province. The ultramafic lamprophyres are believed to be the result of melting enriched Bouvet mantle plume material and represent one of the mantle end members in the Karoo-Ferrar province.

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