Guldvikhaugen granite dykes

Coordinates: UTM33W 0364679 7228543, 65°9'8.8''N 12°6'47.3''E
Primary interests: Science

The outcrops along the shoreline below Guldvikhaugen are composed of two types of rocks: dark greyish calcareous schist displaying folding and ductile shearing, and white granite, partly tourmaline bearing. The latter has intruded as hot magmas into cracks in the schist, forming thin and thick “stripes” on the outcrops. Such plate-shaped bodies of igneous rocks are called dykes.

The granite dykes are the ofspring from a larger intrusion to the east and north. We may count several “generations” of dykes. The earliest have been strongly deformed, whilst the latest cut through all ductile structures, but are displaced by brittle faults. Late dykes can also be seen cutting through the older ones.

Being 100% exposed, the locality provides a unique insight in the mechanism of ductile and brittle deformation, the formation of intrusive dykes. It is a superb example of how relative timing of events seen on an outcrop scale can reveal a fragment of the geological history in the region.

This site is not in use today, is situated next to the road 17 and easy to access.