New carbonatite complex discovered in southern West Greenland


PhotoDuring field work carried out by GEUS in the Nuuk region of southern West Greenland this summer (2005), a new and interesting geological occurrence was found. It is a carbonatite complex consisting of a core of massive carbonatite surrounded by a zone of intensive fracturing, carbonatite veining and fenitisation. The carbonatite has been intruded into Archaean gneisses, and is believed to be much younger than those, although its age is presently unknown. Three in situ lamprophyre dykes were encountered in the vicinity of the carbonatite complex, in addition to several boulders of lamprophyre.

The field work in the area was carried out by GEUS geologists Agnete Steenfelt and Julie Hollis and lasted from 20 to 30 July, 2005. It wasdocumented that the carbonatite magma during its intrusion affected a 10 x 8 km² large area situated close to the margin of the Inland Ice, at 64ºN, 49º45'W. The locality was visited because analyses of available geochemical, mineralogical and aeromagnetic data prior to the field work had suggested the presence of rocks of carbonatitic and/or alkaline composition.

Carbonatites are volcanic rocks of carbonate chemical composition that are known elsewhere to contain high concentrations of economically interesting minerals. Three other complexes of similar size are known from West Greenland. Lamprophyres are interesting in connection with diamond exploration. Though the mineral potential of this particular carbonatite is as yet unknown, its presence will give rise to investigations that may reveal possibilities for future exploitation. GEUS has initiated investigations expected to throw further light on the formation and age of this until now unknown geological feature. The new occurrence is named the Tikiusaaq carbonatite complex and further field work is anticipated for next year.