The age and origin of the Vaasa migmatite complex revisited

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http://hdl.handle.net/10138/166753

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Suikkanen , E , Huhma , H , Kurhila , M & Lahaye , Y 2014 , ' The age and origin of the Vaasa migmatite complex revisited ' Bulletin of the Geological Society of Finland , vol. 86 , pp. 41-55 .

Title: The age and origin of the Vaasa migmatite complex revisited
Author: Suikkanen, Einari; Huhma, Hannu; Kurhila, Matti; Lahaye, Yann
Contributor: University of Helsinki, Department of Geology (-2009)
Date: 2014
Language: eng
Number of pages: 15
Belongs to series: Bulletin of the Geological Society of Finland
ISSN: 0367-5211
URI: http://hdl.handle.net/10138/166753
Abstract: The origin of the Vaasa migmatite complex was studied by using whole-rock Sm-Nd and zircon Lu-Hf and U-Pb data in conjunction with whole-rock major and trace element geochemistry. The concordia ages of five Vaasa area granitoid samples are 1.88-1.86 Ga, constraining the age of peak migmatization. The ages of inherited zircon cores in the samples show two clear age populations at 2.02-1.92 Ga and c. 2.7 Ga, which correspond to ages yielded by a mica schist sample from the adjacent Evijarvi belt, as well as with published values for the Evijarvi belt zircon. The initial epsilon(Nd) values of the Vaasa complex samples are relatively unradiogenic (from -3.0 to -2.0). Such values are comparable to a value (-3.6) calculated for the Evijarvi mica schist, as well as to literature values (from 3.0 to -0.5) for the Evijarvi belt. The average initial zircon epsilon(Hf) values of four of the granitoids range from -10 to -5 and are in agreement with the Nd-isotopic results, whereas the northmost sample has a significantly higher value (+1). The deviation is suggested to result from disequilibrium melting of zircon. The isotopic and geochronological data indicate that the Vaasa complex granitoids formed by partial melting of the Evijarvi belt metasedimentary rocks.
Subject: migmatites
granites
diatexite
metatexite
Svecofennian Orogeny
partial melting
geochronology
absolute age
zircon
U/Pb
Lu/Hf
Sm/Nd
Proterozoic
Paleoproterozoic
South Ostrobothnia
Finland
ND ISOTOPIC EVOLUTION
SM-ND
U-PB
SVECOFENNIAN OROGEN
CRUSTAL ANATEXIS
DETRITAL ZIRCONS
SIERRA-NEVADA
BALTIC SHIELD
LU-HF
CONSTRAINTS
1171 Geosciences
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