Evolution of the Archaean Karelian Province in the Fennoscandian Shield in the light of U–Pb zircon ages and Sm–Nd and Lu–Hf
isotope systematics
Laura S. Lauri
Tom Andersen
Pentti Hölttä
Hannu Huhma
Stuart Graham
10.6084/m9.figshare.3454901.v1
https://geolsoc.figshare.com/articles/dataset/Evolution_of_the_Archaean_Karelian_Province_in_the_Fennoscandian_Shield_in_the_light_of_U_Pb_zircon_ages_and_Sm_Nd_and_Lu_Hf___isotope_systematics/3454901
<p><em>In situ</em> Lu–Hf (laser ablation microprobe–inductively coupled plasma mass spectrometry (LAM-ICPMS)) and U–Pb (LAM-ICPMS, secondary
ionization mass spectrometry (SIMS)) analyses of zircon, and whole-rock Sm–Nd isotope analyses were performed on rocks formed
during magmatic events in three Archaean complexes in the Karelian Province of Fennoscandia (Pudasjärvi, Koillismaa and Iisalmi).
These complexes have U–Pb ages ranging from 3.5 to 2.6 Ga. In Pudasjärvi, sparse xenocrystic cores give ages of 3.6–3.7 Ga
and initial <sup>176</sup>Hf/<sup>177</sup>Hf suggesting influence of a crustal component T ≥ 4.0 Ga (assuming a CHUR-like mantle source). Ages and Nd and Hf isotope
patterns indicate magmatic events at 3.6–3.7 Ga (Siurua, Pudasjärvi with ≥4.0 Ga precursor), 3.2 Ga (Iisalmi, Koillismaa),
2.8 Ga (Pudasjärvi) and 2.7 Ga (Pudasjärvi, Iisalmi). In the Meso- and Palaeoarchaean events, there is no evidence of sources
equivalent to present-day depleted mantle; such sources were, however, involved in the 2.8–2.7 Ga events. ε<sub>Hf</sub> and ε<sub>Nd</sub> are strongly correlated. Contrasts between the Archaean complexes indicate that they evolved separately until <em>c</em>. 2.7 Ga. The age and ε<sub>Hf</sub> pattern of ≤2.8 Ga rocks in the Karelian Province is compatible with a scenario in which the Karelia, Superior, Yilgarn and
Slave cratons were part of a late Archaean supercontinent, but does not constitute proof of the existence of such a supercontinent.
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2016-06-21 12:25:39
Pudasj ärvi Iisalmi
plasma mass spectrometry
Pudasj ärvi
Archaean Karelian Province
magmatic events
Hf isotope patterns
ionization mass spectrometry
SIMS
2.7 Ga
Archaean complexes
Karelian Province
Geology