Universität zu Köln

Kroener, A., Nagel, T. J., Hoffmann, J. E., Liu, X., Wong, J., Hegner, E., Xie, H., Kasper, U., Hofmann, A. and Liu, D. (2018). High-temperature metamorphism and crustal melting at ca. 3.2 Ga in the eastern Kaapvaal craton, southern Africa. Precambrian Res., 317. S. 101 - 117. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1872-7433

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Abstract

The question of whether high-grade metamorphism and crustal melting in the early Archaean were associated with modern-style plate tectonics is a major issue in unravelling early Earth crustal evolution, and the eastern Kaapvaal craton has featured prominently in this debate. We discuss a major ca. 3.2 Ga tectono-magmatic-metamorphic event in the Ancient Gneiss Complex (AGC) of Swaziland, a multiply deformed medium- to high-grade terrane in the eastern Kaapvaal craton consisting of 3.66-3.20 Ga granitoid gneisses and infolded greenstone remnants, metasedimentary assemblages and mafic dykes. We report on a 3.2 Ga granulite-facies assemblage in a metagabbro of the AGC of central Swaziland and relate this to a major thermo-magmatic event that not only affected the AGC but also the neighbouring Barberton granitoid-greenstone terrane. Some previous models have related the 3.2 Ga event in the eastern Kaapvaal craton to subduction processes, but we see no evidence for long, narrow belts and metamorphic facies changes reflecting lithospheric suture zones, and there is no unidirectional asymmetry in the thermal structure across the entire region from Swaziland to the southern Barberton granite-greenstone terrane as is typical of Phanerozoic and Proterozoic belts. Instead, we consider an underplating event at ca. 3.2 Ga, giving rise to melting in the lower crust and mixing with mantle derived under- and intraplated mafic magma to generate the voluminous granitoid assemblages now observed in the AGC and the southern Barberton terrane. This is compatible with large-scale crustal reworking during a major thermo-magmatic event and the apparent lack of a mafic lower crust in the Kaapvaal craton as shown by seismic data.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Kroener, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nagel, T. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoffmann, J. E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Liu, X. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wong, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hegner, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Xie, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kasper, U. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hofmann, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Liu, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-170835
DOI:	10.1016/j.precamres.2018.08.007
Journal or Publication Title:	Precambrian Res.
Volume:	317
Page Range:	S. 101 - 117
Date:	2018
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1872-7433
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ANCIENT GNEISS COMPLEX; BARBERTON GREENSTONE-BELT; ARCHEAN CONTINENTAL-CRUST; WEST GREENLAND; MOUNTAIN LAND; NORTHWESTERN CANADA; LITHOSPHERIC MANTLE; PLATE-TECTONICS; TERRANE SOUTH; HF ISOTOPES Multiple languages Geosciences, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17083