Growth of subcontinental lithospheric mantle beneath Zimbabwe started at or before 3.8 Ga: Re-Os study on chromites

Th F. Nägler; J. D. Kramers; B. S. Kamber; R. Frei; M. D.A. Prendergast

doi:10.1130/0091-7613(1997)025<0983:GOSLMB>2.3.CO;2

Growth of subcontinental lithospheric mantle beneath Zimbabwe started at or before 3.8 Ga: Re-Os study on chromites

Th F. Nägler^*, J. D. Kramers, B. S. Kamber, R. Frei, M. D.A. Prendergast

^*Corresponding author for this work

Geology

59 Citations (Scopus)

Abstract

Re-Os isotope results on chromites separated from age-constrained Archean (2.7 to 3.5 Ga) ultramafic intrusions in the Zimbabwe craton show that chromites average a present-day ¹⁸⁷ Os/ ¹⁸⁸ Os ratio of 0.1066, significantly below the bulk silicate Earth value. The source reservoir is interpreted to reflect the Zimbabwean subcontinental lithospheric mantle (SCLM). Archean Re depletion of the SCLM has previously been postulated on the basis of xenolith studies from southern Africa, Siberia, and the Wyoming craton. Because our samples are age constrained, however, the Re-Os data also shed light on the evolution of the Archean SCLM through time. They indicate that the Zimbabwean SCLM began to be separated from asthenospheric mantle before 3.8 Ga and grew quasi-continuously throughout the Archean. This result is reconciled with present-day SCLM data in forward modeling.

Original language	English
Journal	Geology
Volume	25
Issue number	11
Pages (from-to)	983-986
Number of pages	4
ISSN	0091-7613
DOIs	https://doi.org/10.1130/0091-7613(1997)025<0983:GOSLMB>2.3.CO;2
Publication status	Published - 1 Jan 1997

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10.1130/0091-7613(1997)025<0983:GOSLMB>2.3.CO;2

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title = "Growth of subcontinental lithospheric mantle beneath Zimbabwe started at or before 3.8 Ga: Re-Os study on chromites",

abstract = " Re-Os isotope results on chromites separated from age-constrained Archean (2.7 to 3.5 Ga) ultramafic intrusions in the Zimbabwe craton show that chromites average a present-day 187 Os/ 188 Os ratio of 0.1066, significantly below the bulk silicate Earth value. The source reservoir is interpreted to reflect the Zimbabwean subcontinental lithospheric mantle (SCLM). Archean Re depletion of the SCLM has previously been postulated on the basis of xenolith studies from southern Africa, Siberia, and the Wyoming craton. Because our samples are age constrained, however, the Re-Os data also shed light on the evolution of the Archean SCLM through time. They indicate that the Zimbabwean SCLM began to be separated from asthenospheric mantle before 3.8 Ga and grew quasi-continuously throughout the Archean. This result is reconciled with present-day SCLM data in forward modeling. ",

author = "N{\"a}gler, {Th F.} and Kramers, {J. D.} and Kamber, {B. S.} and R. Frei and Prendergast, {M. D.A.}",

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T1 - Growth of subcontinental lithospheric mantle beneath Zimbabwe started at or before 3.8 Ga

T2 - Re-Os study on chromites

AU - Nägler, Th F.

AU - Kramers, J. D.

AU - Kamber, B. S.

AU - Frei, R.

AU - Prendergast, M. D.A.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - Re-Os isotope results on chromites separated from age-constrained Archean (2.7 to 3.5 Ga) ultramafic intrusions in the Zimbabwe craton show that chromites average a present-day 187 Os/ 188 Os ratio of 0.1066, significantly below the bulk silicate Earth value. The source reservoir is interpreted to reflect the Zimbabwean subcontinental lithospheric mantle (SCLM). Archean Re depletion of the SCLM has previously been postulated on the basis of xenolith studies from southern Africa, Siberia, and the Wyoming craton. Because our samples are age constrained, however, the Re-Os data also shed light on the evolution of the Archean SCLM through time. They indicate that the Zimbabwean SCLM began to be separated from asthenospheric mantle before 3.8 Ga and grew quasi-continuously throughout the Archean. This result is reconciled with present-day SCLM data in forward modeling.

AB - Re-Os isotope results on chromites separated from age-constrained Archean (2.7 to 3.5 Ga) ultramafic intrusions in the Zimbabwe craton show that chromites average a present-day 187 Os/ 188 Os ratio of 0.1066, significantly below the bulk silicate Earth value. The source reservoir is interpreted to reflect the Zimbabwean subcontinental lithospheric mantle (SCLM). Archean Re depletion of the SCLM has previously been postulated on the basis of xenolith studies from southern Africa, Siberia, and the Wyoming craton. Because our samples are age constrained, however, the Re-Os data also shed light on the evolution of the Archean SCLM through time. They indicate that the Zimbabwean SCLM began to be separated from asthenospheric mantle before 3.8 Ga and grew quasi-continuously throughout the Archean. This result is reconciled with present-day SCLM data in forward modeling.

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Growth of subcontinental lithospheric mantle beneath Zimbabwe started at or before 3.8 Ga: Re-Os study on chromites

Abstract

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