D3 Article in a professional conference publication

Post-kinematic mafic dykes in southern part of Central Svecofennia, Finland




AuthorsJ. Kara, M. Väisänen, Y. Lahaye, H. O’Brien

EditorsAnnakaisa Korja, Ilmo Kukkonen, Suvi Heinonen, Kati Oinonen, Katriina Arhe, Olav Eklund, Fredrik Karell, Elena Kozlovskaya, Arto Luttinen, Raimo Lahtinen, Juha Lunkka, Vesa Nykänen, Markku Poutanen, Eija Tanskanen, Timo Tiira

Conference nameLithosphere

Publishing placeHelsinki

Publication year2016

JournalReport - Institute of seismology. University of helsinki

Book title Lithosphere 2016: Ninth symposium on the Structure, Composition and Evolution of the Lithosphere in Fennoscandia

Series titleReport - institute of seismology. university of helsinki. s

Number in series65

First page 47

Last page50

ISBN978-952-10-5081-7

eISBN978-952-10-9282-5

Web address http://www.seismo.helsinki.fi/pdf/Lito2016.pdf(external)


Abstract

The geochemical composition of seven post-kinematic mafic dykes in southern part of Central Svecofennia have been studied. Two dykes have been selected for in situ zircon U-Pb geochronology and one for in situ zircon Lu-Hf isotope analysis.These c. 1.86 Ga dykes can be divided into two subgroups by their geochemical characteristics: i) an enriched type with Nb contents up to 42 ppm, high contents of certain fluid mobile elements such as F, Ba, Sr, K2O and LREE and elevated contents of Fe2O3, Ti2O and P2O5, and ii) a primitive type with high MgO and Cr content. The primitive dyke exhibit positive, average c. +3, initial εHf values. The geochemical data combined with the petrological and the field observations suggest that the dykes are juvenile and derived from a subduction-enriched mantle source in a within-plate environment during the post-kinematic stage of the Svecofennian orogeny.


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