Universität zu Köln

Suhr, Nils ORCID: 0000-0003-4380-4554, Hoffmann, J. Elis ORCID: 0000-0001-6670-1393, Kroener, Alfred and Schroeder, Sebastian (2015). Archaean granulite-facies paragneisses from central Swaziland: inferences on Palaeoarchaean crustal reworking and a complex metamorphic history. J. Geol. Soc., 172 (1). S. 139 - 153. BATH: GEOLOGICAL SOC PUBL HOUSE. ISSN 2041-479X

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Abstract

We present a petrographic, petrological, geochemical, and geochronological study (U-Pb/Lu-Hf) on granulite-facies paragneisses of the Mahamba Gneiss Complex in central Swaziland, eastern Kaapvaal Craton. Our data suggest that prograde metamorphism occurred at c. 3.07 Ga. Dating of detrital zircons of a metapelite in combination with geochronological and ambiguous structural relationships with granitoid gneisses suggests two possible scenarios: (1) the time of deposition of the sedimentary protoliths is prior to c. 3.58 Ga; (2) c. 3.58 Ga granitoid crust was the basement for the sedimentary protoliths. Furthermore, enrichment in Ni and Cr in the Mahamba metasediments may originate from erosion of a greenstone terrane similar in composition to the dominantly mafic and ultramafic lithologies of the Barberton Greenstone Belt or Dwalile supracrustal belt. Evidence for an older crustal basement is provided by the oldest detrital zircons, which yield ages up to c. 3.7 Ga. Because the metamorphic conditions of metapelitic rocks have no similarity to P-T paths of modern subduction-collision tectonic settings we conclude that the metamorphic history of the Mahamba Gneiss Complex cannot be explained by this model. We propose that deformation and metamorphism occurred through intracratonic contraction and a thermal event possibly related to Mpuluzi batholith emplacement.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Suhr, Nils UNSPECIFIED orcid.org/0000-0003-4380-4554 UNSPECIFIED Hoffmann, J. Elis UNSPECIFIED orcid.org/0000-0001-6670-1393 UNSPECIFIED Kroener, Alfred UNSPECIFIED UNSPECIFIED UNSPECIFIED Schroeder, Sebastian UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-416978
DOI:	10.1144/jgs2014-007
Journal or Publication Title:	J. Geol. Soc.
Volume:	172
Number:	1
Page Range:	S. 139 - 153
Date:	2015
Publisher:	GEOLOGICAL SOC PUBL HOUSE
Place of Publication:	BATH
ISSN:	2041-479X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ANCIENT GNEISS COMPLEX; TEMPERATURE-TIME PATHS; BARBERTON GREENSTONE-BELT; U-PB ISOTOPE; KAAPVAAL CRATON; SOUTH-AFRICA; CONTINENTAL-CRUST; REGIONAL METAMORPHISM; CENTRAL AUSTRALIA; ARUNTA INLIER Multiple languages Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/41697