Universität zu Köln

Scott, J. M., Waight, T. E., van der Meer, Q. H. A., Palin, J. M., Cooper, A. F. and Muenker, C. (2014). Metasomatized ancient lithospheric mantle beneath the young Zealandia microcontinent and its role in HIMU-like intraplate magmatism. Geochem. Geophys. Geosyst., 15 (9). S. 3477 - 3502. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 1525-2027

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Abstract

There has been long debate on the asthenospheric versus lithospheric source for numerous intraplate basalts with ocean island basalt (OIB) and high time-integrated U/Pb (HIMU)-like source signatures that have erupted through the Zealandia continental crust. Analysis of 157 spinel facies peridotitic mantle xenoliths from 25 localities across Zealandia permits the first comprehensive regional description of the subcontinental lithospheric mantle (SCLM) and insights into whether it could be a source to the intraplate basalts. Contrary to previous assumptions, the Oligocene-Miocene Zealandia SCLM is highly heterogeneous. It is composed of a refractory craton-like domain (West Otago) adjacent to several moderately fertile domains (East Otago, North Otago, Auckland Islands). Each domain has an early history decoupled from the overlying Carboniferous and younger continental crust, and each domain has undergone varying degrees of depletion followed by enrichment. Clinopyroxene grains reveal trace element characteristics (low Ti/Eu, high Th/U) consistent with enrichment through reaction with carbonatite. This metasomatic overprint has a composition that closely matches HIMU in Sr, PbNd isotopes. However, clinopyroxene Hf isotopes are in part highly radiogenic and decoupled from the other isotope systems, and also mostly more radiogenic than the intraplate basalts. If the studied spinel facies xenoliths are representative of the thin Zealandia SCLM, the melting of garnet facies lithosphere could only be the intraplate basalt source if it had a less radiogenic Hf-Nd isotope composition than the investigated spinel facies, or was mixed with asthenosphere-derived melts containing less radiogenic Hf.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Scott, J. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Waight, T. E. UNSPECIFIED UNSPECIFIED UNSPECIFIED van der Meer, Q. H. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Palin, J. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cooper, A. F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muenker, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-429387
DOI:	10.1002/2014GC005300
Journal or Publication Title:	Geochem. Geophys. Geosyst.
Volume:	15
Number:	9
Page Range:	S. 3477 - 3502
Date:	2014
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	1525-2027
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SOUTHERN NEW-ZEALAND; METAMORPHIC CORE COMPLEX; AUCKLAND VOLCANIC FIELD; LATE CENOZOIC BASALTS; OCEANIC UPPER-MANTLE; CARBONATITE METASOMATISM; TRACE-ELEMENT; GEOCHEMICAL EVOLUTION; PERIDOTITE XENOLITHS; DYKE-SWARM Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/42938