Aarhus Universitets segl

Masters thesis: Petrology of the 2.7 Ga Vend Om Intrusion, Skjoldungen Alkaline Province, SE Greenland

Bjørn Peder Maarupgaard

Congratulations to Bjørn on finishing his Masters.

Bjørn was supervised by Christian Tegner (ESP) and Thomas F. Kokfelt (GEUS).



The Vend Om Intrusion is part of the Skjoldungen Alkaline Province that forms a belt of Archean (2720-2665 Ma) intrusions in South-East Greenland ranging from pyroxenites and hornblendeites over hornblende-rich norites and monzonites, to granite, syenite and carbonatite.

The Vend Om Intrusion is a small 325 x 450 m oval outcrop of a hornblende-gabbronorite layered intrusion. The contact to the host gneiss is steep, near vertical, and is often intruded by felsic sheets up to 3 m wide extending up to 40 meters into the intrusion. The outermost, up to 50 m thick, Marginal Zone dips steeply and consists of hornblene-mela-gabbronorite. The inner Layered Series in the centre of the intrusion consists of Fe-Ti oxide-bearing hornblende-gabbronorite and shows prominent cm- to m-scale modal layering, including up to 1.5 m thick layers and irregular bodies with up to 75% magnetite and 5% ilmenite (with hercynite). Overall, the modal layering defines a concentric structure that is steeply inward-dipping.

In order to examine the magma chamber processes and subsolidus modifications for the Vend Om Intrusion, the following data are presented: Petrography and mineral chemistry of 51 samples along with whole rock geochemistry data of 93 samples, and a SW-NE transect of samples through the intrusion.