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Ulf Söderlund

Ulf Söderlund

Professor

Ulf Söderlund

Mafic magmatism in the Bakhuis Granulite Belt (western Suriname) : relationship with charnockite magmatism and UHT metamorphism

Författare

  • Martijn Klaver
  • Emond W F de Roever
  • Antonia C D Thijssen
  • Wouter Bleeker
  • Ulf Söderlund
  • Kevin Chamberlain
  • Richard Ernst
  • Jasper Berndt
  • Armin Zeh

Summary, in English

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.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2016-01-02

Språk

Engelska

Sidor

203-218

Publikation/Tidskrift/Serie

GFF

Volym

138

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Taylor & Francis

Ämne

  • Geology

Nyckelord

  • Bakhuis Granulite Belt
  • geochronology
  • Guiana Shield
  • metagabbro
  • zircon geochemistry

Aktiv

Published

ISBN/ISSN/Övrigt

  • ISSN: 1103-5897