Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component?

Journal article
(Original article)


Publication Details

Author(s): Günther T, Haase K, Junge M, Oberthür T, Wölki D, Krumm S
Journal: Lithos
Publisher: ELSEVIER SCIENCE BV
Publication year: 2018
Volume: 310
Pages range: 332-341
ISSN: 0024-4937
Language: English


Abstract

Platiniferous dunite pipes occur in the lower mafic/ultramafic portion of the Rustenburg layered Suite of the Bushveld large igneous province (LIP). Olivine compositions in these pipes range from forsterite (Fo) 80 to 35 mol% and suggest crystallization from variably evolved magmas at high temperatures (similar to 1200 degrees C). The most primitive olivines are from a stock unit and have the highest contents of Ni (>0.15 wt%) and lowest contents of Mn (<0.3 wt%). Fractional crystallization and partial melting of pyroxenite host rock play a significant role in the formation of the fayalitic olivines with its high Mn contents (>0.3 wt%). High delta O-18 values of olivine (5.7-7.0 parts per thousand) and pyroxene (6.7-7.4 parts per thousand) are akin to those of the Lower and Critical Zone of the Bushveld intrusion suggesting a common origin. The constant high O isotope ratios with variable Fo contents in the olivines are unlike trends observed in olivine phenocrysts in magmas forming by assimilation-fractional crystallization. We suggest that the high delta O-18 in the most primitive dunites reflect that of the primary melt of the Bushveld pipes, indicating either a bulk assimilation of crust prior to pipe formation or a contribution from recycled oceanic crust in the subcontinental lithospheric mantle (SCLM). The latter scenario is supported by the high Ni/Mn ratios in primitive pipe olivine that might be inherited from melting of a pyroxene-rich mantle source. (C) 2018 Elsevier B.V. All rights reserved.


FAU Authors / FAU Editors

Günther-Fellner, Thomas
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik
Krumm, Stefan Dr.
Lehrstuhl für Endogene Geodynamik
Wölki, Dominic
Lehrstuhl für Endogene Geodynamik


External institutions with authors

Albert-Ludwigs-Universität Freiburg
Bundesanstalt für Geowissenschaften und Rohstoffe (BGR)


How to cite

APA:
Günther, T., Haase, K., Junge, M., Oberthür, T., Wölki, D., & Krumm, S. (2018). Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component? Lithos, 310, 332-341. https://dx.doi.org/10.1016/j.lithos.2018.04.017

MLA:
Günther, Thomas, et al. "Oxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component?" Lithos 310 (2018): 332-341.

BibTeX: 

Last updated on 2019-07-02 at 22:10

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