Alkaline Rocks and Carbonatites of the World

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Occurrence number: 
Longitude: -22.5, Latitude: 72.25

The 120 km2 Forchhammer complex occupies the greater part of the Cape Simpson peninsular at the southern end of Traill 0. It comprises principally peralkaline syenites which domed and metamorphosed Jurassic and Cretaceous sediments containing basalt sills. The principal rocks of the complex are alkali amphibole-and pyroxene-bearing quartz syenites with minor granite and quartz-free syenite. Dyke rocks include rockallite porphyry, aegirine granophyre and spherulitic quartz syenite porphyry. Extensive areas of 'tuff-breccias' are also shown on the large scale coloured geological map of Schaub (1942).

K-Ar gave 38±2 Ma (D. C. Rex, quoted in Gleadow and Brooks, 1979, Table 4).
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. REINHARD, M. 1942. Petrographische Beschreibung der Gesteine der Traill Insel. Eclogae Geologicae Helvetiae, 35: 49-54. SCHAUB, H.P. 1942. Zur Geologie der Traill Insel (Nordest-Gronland). Eclogae Geologicae Helvetiae, 35: 1-49
Fig. 86 Kap Parry and Forchhammer (Kap Simpson) (after Schaub, 1942).
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