Original paper

Generation, transportation and emplacement of postand anorogenic magmas in the Fennoscandian shield

Eklund, Olav

Abstract

To receive detailed information about the history coarse porphyritic ganites from different tectonic setting (post- and anorogenic), mineral inclusions in quartz and K-feldsparmegacrysts were studied. The result of the project was that the megacrysts were formed in mid-crustal magmachambers some 30 Ma before the emplacement of the granites in the upper crust. Anorogenic granites are known to represent crystallization in reduced environments (low Mg# of the mafic silicates). However, the mineral chemistry of mafic silicates in K-feldspar megacrysts is in contrast to this. The minerals have high Mg# and are enriched in Ba and Sr - typical features for post-orogenic granites. We thus don't rule out the possibility that there may be a petrogenetic connection between post- and anorogenic granites.