Among the concentration of Gardar dykes in the Isortoq area are five giant dykes, four of which are multiple and consist of alkali gabbro, augite syenite and granite whilst one is essentially larvikite (Bridgwater and Coe, 1970). Individual dykes are silica-undersaturated in the east and oversaturated in the west (D. Bridgwater, quoted by Emeleus and Upton, 1976, p. 164). Both syenites and granites are peralkaline but petrographic details are not available.
BRIDGWATER, D. and COE, K. 1970. The role of stoping in the emplacemnt of the giant dykes of Isortoq, South Greenland. In G. Newall and R. Rast (Eds). Mechanism of Igneous Intrusion. Special Issue, Geological Journal, 2: 67-78.
EMELEUS, C.H. and UPTON, B.G.J. 1976. The Gardar period in southern Greenland. In A. Escher and W.S. Watt (Eds). Geology of Greenland. Gronlands Geologiske Undersogelse: 153-81.