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The Central Domain of the Ketilidian Orogen in South Greenland preserves two magmatic events that provide insight into crustal architecture and represent a major contribution to continental crustal growth in connection with the assembly of the late Paleoproterozoic-Mesoproterozoic supercontinent Columbia/Nuna. This study provides zircon U-Pb geochronology for the western parts of the Central Domain and, combined with previous published age data, documents crustal evolution in the orogeny. The geochronological data indicate an initial volumetrically-minor magmatic event at ca. 1850 Ma, referred to here as the Older Julianehåb Igneous Suite, followed by a pause in magmatic activity. This is followed by the Younger Julianehåb Igneous Suite, a major pulse of magmatism (comparable to magmatic flare-ups in Phanerozoic arcs) between ca. 1814 and 1795 Ma. The adjacent arcs in the Makkovik Province, Canada, and the Transscandinavian Igneous Belt, Scandinavia, preserve similarly-aged magmatic events and appear to young from west to east. Exposure levels in the Makkovik Province are shallower than in the Ketilidian Orogen, and shallower supracrustal deposits are significantly more abundant in the Makkovik Province, indicating significant differences in modern erosion levels.
Vestergaard et al. (Fri,) studied this question.