Universität zu Köln

Hoffmann, J. Elis ORCID: 0000-0001-6670-1393, Nagel, Thorsten J., Muenker, Carsten, Naeraa, Tomas and Rosing, Minik T. (2014). Constraining the process of Eoarchean TTG formation in the Itsaq Gneiss Complex, southern West Greenland. Earth Planet. Sci. Lett., 388. S. 374 - 387. AMSTERDAM: ELSEVIER. ISSN 1385-013X

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Abstract

We present new major and trace element, high-precision high-field-strength-element, hafnium and neodymium isotope data for well preserved Eoarchean TTGs within the Itsaq Gneiss Complex (IGC) of southern West Greenland. These data are combined with thermodynamic model predictions of partial melting and fractional crystallization to gain new insights into continental crust formation in the Archean. Our results show that the observed compositional range of Eoarchean TTGs can be explained by a combination two processes: (1) 5-25% partial melting of amphibolite within thickened mafic crust and (2) subsequent fractional crystallization processes. The Eoarchean TTG suite of SW Greenland probably formed through mixing of melt batches that originally formed at different source depths between 10 and 14 kbar and ponded as plutons at mid-crustal levels. The trace element compositions of some TTGs point to subsequent fractional crystallization processes involving plagioclase, clinopyroxene, amphibole and garnet. Our model is consistent with recent studies proposing that the Eoarchean Itsaq Gneiss Complex TTGs from the IGC formed by re-working of mafic protocrust that stabilized as accreted juvenile crustal terranes in the Eoarchean. The model is also in good agreement with field observations from the area. (C) 2013 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hoffmann, J. Elis UNSPECIFIED orcid.org/0000-0001-6670-1393 UNSPECIFIED Nagel, Thorsten J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muenker, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Naeraa, Tomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Rosing, Minik T. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-445864
DOI:	10.1016/j.epsl.2013.11.050
Journal or Publication Title:	Earth Planet. Sci. Lett.
Volume:	388
Page Range:	S. 374 - 387
Date:	2014
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1385-013X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ISUA GREENSTONE-BELT; EARLY CONTINENTAL-CRUST; RARE-EARTH-ELEMENTS; LU-HF; U-PB; SUPRACRUSTAL BELT; ARCHEAN CRUST; 3.8 GA; ISOTOPIC COMPOSITIONS; GEOCHEMICAL PATTERNS Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/44586