Crustal reactivation in northern Sweden : the Vettasjärvi granite

• The 1.8 Ga old Vettasjärvi granite belongs to a widespread granite type in northern Sweden and northern Finland. It is a leucocratic, generally massive, pink granite covering a large area but possesses a small vertical extent. Foliated varieties occur and gneissic ghost structures are common. Gradual transitions from biotite-rich gneiss to granite have also been observed. Mineralogy and major and trace element geochemistry demonstrate the minimum-melt character of the Vettasjärvi granite. The low contents of elements such as Nb, Y, Sn and F indicate that it is also undifferentiated. Initial εNd values between −6.2 and −8.2 suggest that the Vettasjärvi granite was generated by crustal anatexis with a major Archaean component as source material. REE contents support this conclusion. Molar proportion ratios Al2O3/Na2O+K2O+CaO lower than 1.1, combined with δ18O values between 8 and 5 suggest that little or no pelitic sedimentary material was involved in the genesis. The Vettasjärvi granite is not a single intrusion, but more likely a zone of remobilisation where granite was generated and gently and irregularly emplaced.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)

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Applied Geology

Tillämpad geologi

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