Mafic magmatism in the Bakhuis Granulite Belt

M. Klaver, E.W.F. de Roever, A.C.D. Thijssen, W. Bleeker, U. Söderlund, K. Chamberlain, R. Ernst, J. Berndt, A. Zeh

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The Bakhuis Granulite Belt (BGB) is a metamorphic terrain within the Guiana Shield that experienced ultrahigh-temperature (UHT) metamorphism at 2.07–2.05Ga. In the southwest of the BGB, the Kabalebo charnockites were emplaced at ca. 1.99Ga and thus postdate UHT metamorphism by at least 60Myr. Two generations of gabbroic intrusions have been recognized within the BGB, which could act as a heat source for the two UHT events. A younger generation of tholeiitic “Charlie” gabbros yields a baddeleyite U/Pb age of 1971±15Ma. The presence of a metamorphic overprint indicates that the hornblende-bearing “Moi–Moi” metagabbros predate the Charlie gabbros. Large zircons with complex zoning patterns are found in a Moi–Moi metagabbro sample. The main growth domains of these zircons give an age of 1984±4Ma, which is indistinguishable from the surrounding charnockites. Matching trace element and Hf isotope characteristics indicate that the complex zircons are derived from the charnockites. We argue that the emplacement of the metagabbros and charnockite magmatism were contemporaneous and that zircon grains from the charnockitic melt were mechanically transferred to the gabbroic bodies during magma mingling. The new ages for the gabbroic bodies in the BGB confirm that they are contemporaneous with, and the likely heat source for, charnockite magmatism, but that they are not associated with the 2.07–2.05Ga UHT event. Furthermore, the new ages and recognition of the Moi–Moi metagabbros as an Alaskan-type complex provide the first direct evidence for late Transamazonian subduction zone magmatism in the Guiana Shield.
Original languageEnglish
JournalGFF
DOIs
Publication statusPublished - 2015

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granulite
magmatism
zircon
ultrahigh temperature metamorphism
charnockite
heat source
shield
baddeleyite
metagabbro
hornblende
zoning
subduction zone
emplacement
temperature
magma
trace element
melt
isotope

Cite this

Klaver, M., de Roever, E. W. F., Thijssen, A. C. D., Bleeker, W., Söderlund, U., Chamberlain, K., ... Zeh, A. (2015). Mafic magmatism in the Bakhuis Granulite Belt. GFF. https://doi.org/10.1080/11035897.2015.1061591
Klaver, M. ; de Roever, E.W.F. ; Thijssen, A.C.D. ; Bleeker, W. ; Söderlund, U. ; Chamberlain, K. ; Ernst, R. ; Berndt, J. ; Zeh, A. / Mafic magmatism in the Bakhuis Granulite Belt. In: GFF. 2015.
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abstract = "The Bakhuis Granulite Belt (BGB) is a metamorphic terrain within the Guiana Shield that experienced ultrahigh-temperature (UHT) metamorphism at 2.07–2.05Ga. In the southwest of the BGB, the Kabalebo charnockites were emplaced at ca. 1.99Ga and thus postdate UHT metamorphism by at least 60Myr. Two generations of gabbroic intrusions have been recognized within the BGB, which could act as a heat source for the two UHT events. A younger generation of tholeiitic “Charlie” gabbros yields a baddeleyite U/Pb age of 1971±15Ma. The presence of a metamorphic overprint indicates that the hornblende-bearing “Moi–Moi” metagabbros predate the Charlie gabbros. Large zircons with complex zoning patterns are found in a Moi–Moi metagabbro sample. The main growth domains of these zircons give an age of 1984±4Ma, which is indistinguishable from the surrounding charnockites. Matching trace element and Hf isotope characteristics indicate that the complex zircons are derived from the charnockites. We argue that the emplacement of the metagabbros and charnockite magmatism were contemporaneous and that zircon grains from the charnockitic melt were mechanically transferred to the gabbroic bodies during magma mingling. The new ages for the gabbroic bodies in the BGB confirm that they are contemporaneous with, and the likely heat source for, charnockite magmatism, but that they are not associated with the 2.07–2.05Ga UHT event. Furthermore, the new ages and recognition of the Moi–Moi metagabbros as an Alaskan-type complex provide the first direct evidence for late Transamazonian subduction zone magmatism in the Guiana Shield.",
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Klaver, M, de Roever, EWF, Thijssen, ACD, Bleeker, W, Söderlund, U, Chamberlain, K, Ernst, R, Berndt, J & Zeh, A 2015, 'Mafic magmatism in the Bakhuis Granulite Belt' GFF. https://doi.org/10.1080/11035897.2015.1061591

Mafic magmatism in the Bakhuis Granulite Belt. / Klaver, M.; de Roever, E.W.F.; Thijssen, A.C.D.; Bleeker, W.; Söderlund, U.; Chamberlain, K.; Ernst, R.; Berndt, J.; Zeh, A.

In: GFF, 2015.

Research output: Contribution to JournalArticleAcademicpeer-review

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T1 - Mafic magmatism in the Bakhuis Granulite Belt

AU - Klaver, M.

AU - de Roever, E.W.F.

AU - Thijssen, A.C.D.

AU - Bleeker, W.

AU - Söderlund, U.

AU - Chamberlain, K.

AU - Ernst, R.

AU - Berndt, J.

AU - Zeh, A.

PY - 2015

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N2 - The Bakhuis Granulite Belt (BGB) is a metamorphic terrain within the Guiana Shield that experienced ultrahigh-temperature (UHT) metamorphism at 2.07–2.05Ga. In the southwest of the BGB, the Kabalebo charnockites were emplaced at ca. 1.99Ga and thus postdate UHT metamorphism by at least 60Myr. Two generations of gabbroic intrusions have been recognized within the BGB, which could act as a heat source for the two UHT events. A younger generation of tholeiitic “Charlie” gabbros yields a baddeleyite U/Pb age of 1971±15Ma. The presence of a metamorphic overprint indicates that the hornblende-bearing “Moi–Moi” metagabbros predate the Charlie gabbros. Large zircons with complex zoning patterns are found in a Moi–Moi metagabbro sample. The main growth domains of these zircons give an age of 1984±4Ma, which is indistinguishable from the surrounding charnockites. Matching trace element and Hf isotope characteristics indicate that the complex zircons are derived from the charnockites. We argue that the emplacement of the metagabbros and charnockite magmatism were contemporaneous and that zircon grains from the charnockitic melt were mechanically transferred to the gabbroic bodies during magma mingling. The new ages for the gabbroic bodies in the BGB confirm that they are contemporaneous with, and the likely heat source for, charnockite magmatism, but that they are not associated with the 2.07–2.05Ga UHT event. Furthermore, the new ages and recognition of the Moi–Moi metagabbros as an Alaskan-type complex provide the first direct evidence for late Transamazonian subduction zone magmatism in the Guiana Shield.

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DO - 10.1080/11035897.2015.1061591

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Klaver M, de Roever EWF, Thijssen ACD, Bleeker W, Söderlund U, Chamberlain K et al. Mafic magmatism in the Bakhuis Granulite Belt. GFF. 2015. https://doi.org/10.1080/11035897.2015.1061591