Geological observations in the southern West Greenland basement from Ameralik to Frederikshåb Isblink in 2008

Abstract

began a project in collaboration with the Bureau of Minerals and Petroleum of Greenland with the aim to publish a webbased, seamless digital map of the Precambrian bedrock between 61°30 and 64°N in southern West Greenland. Such a map will be helpful for the mineral exploration industry and for basic research. Producing an updated digital map requires additional field work revisiting key localities to collect samples for geochemistry, geochronology and metamorphic petrology. The new data will help us to test and refine existing models and improve general understanding of the geological evolution of the area. Here we summarise some results from the 2008 field activities between Ame ralik in the north and Frederikshab Is blink in the south (Fig. 1). The area was mapped in the 1960s and 1970s, and although the 1:100 000-scale maps are of excellent quality, they do not include more recent developments in geochro nology, thermobarometry and geochemistry. A notable exception is the Fiske naesset complex (Fig. 1), which has re ceived considerable attention after it was first mapped (Ellitsgaard-Ras mus sen & Mouritzen 1954; Wind ley et al., 1973; Windley & Smith, 1974; Myers 1985). New tectonic models have been developed since the original 1:100 000 maps were produced, and the tectonic evolution has been com monly ex plained in terms of terrane accretion (Friend et al. 1996). Friend’s model de fines a number of boundaries that separate terranes of different age and origin and which might have contrasting tectono-metamorphic histories prior to terrane accretion. The current project area includes the northern part and proposed boundary of the Tasiusarsuaq terrane, which was amalgamated with the terranes to the north at 2.72 Ga, when regional metamorphism affected the region (Friend et al. 1996). In addition, Windley & Garde