Wikipedia
Arvidsjaur porphyry
Arvidsjaur porphyry (Swedish: Arvidsjaurporfyr) is a group of igneous rocks of intermediate to felsic composition found near Arvidsjaur in northern Sweden.[1] The Arvidsjaur Porphyry formed 1,870 to 1,880 million years ago during the Paleoproterozoic Era.[1]
Most of the porphyry have well-preserved primary structures and textures which have allowed to interpret much of Arvidsjaur porphyry to be ignimbrites.[2] While much of the porphyryry have rhyolite compositions some parts that are interpreted as lava flows are made up of andesite with plagioclase phenocrysts.[1]
References edit
- ^ a b c Lundqvist, Thomas (2009). Porfyr i Sverige: En geologisk översikt (in Swedish). pp. 26–27. ISBN 978-91-7158-960-6.
- ^ "arvidsjaurporfyr". Nationalencyklopedin (in Swedish). Retrieved 20 December 2019.