Alkaline Rocks and Carbonatites of the World

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Kialineq

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Occurrence number: 
063-00-020
Country: 
Greenland
Location: 
Longitude: -33.08, Latitude: 66.08

The Kialineq centre extends over about 30x10 km and comprises a number of quartz syenite and granite plutons, emplacement of which was by cauldron subsidence with the formation of ring dykes (Brown and Becker, 1986). To the south of these intrusions lies the earlier Imilik gabbro which is layered throughout (Deer, 1976, Fig. 1_359). Associated with the felsic intrusions is an extensive complex of mixed acid and basic rocks with apparent chilling of basic against acid, basic pillow structures and net-veining. The main quartz syenites are generally variable in composition but typically comprise perthite, a little interstitial quartz, ferrohedenbergitic to ferroaugitic pyroxenes partly replaced by amphibole, fayalite and biotite; ferrohornblende is the principal mafic mineral in some areas and rare chevkinite is found. Less abundant but more alkaline varieties of syenite contain pyroxene zoned to aegirine-augite rims and surrounded by alkali amphibole; aenigmatite may be present. The principal granite has biotite as the sole mafic mineral. A small area of volcanic rocks has been preserved by down faulting in one area, and includes peralkaline rhyolites. Analyses of rocks and a range of minerals will be found in Brown and Becker (1986), Brown et al. (1877) and Deer (1976).

Age: 
A Rb-Sr isochron on whole rocks gave 35±2 Ma and K-Ar on biotites gave a mean of 35.9 Ma and for hornblendes 35.4 Ma. A weighted mean of eight zircon and apatite fission-track ages is 36.2±0.4 Ma (Gleadow and Brooks, 1979, p. 51).
References: 
BROWN, P.E. and BECKER, S.M. 1986. Fractionation, hybridisation and magma-mixing in the Kialineq centre East Greenland. Contributions to Mineralogy and Petrology, 92: 57-70. BROWN, P.E., BREEMEN, O.van, NOBLE, R.H. and MACINTYRE, R.M. 1977. Mid-Tertiary igneous activity in East Greenland - the Kialineq complex. Contributions to Mineralogy and Petrology, 64: 109-22. DEER, W.A. 1976. Tertiary igneous rocks between Scoresby Sund and Kap Gustav Holm, East Greenland. In A. Escher and W.S. Watt (Eds). Geology of Greenland. Gronlands Geologiske Undersogelse: 404-29. GLEADOW, A.J.W. and BROOKS, C.K. 1979. Fission track dating, thermal histories and tectonics of igneous intrusions in East Greenland. Contributions to Mineralogy and Petrology, 71: 45-60
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