Evidence of mid-Proterozoic granite formation in the Isua area

F Kalsbeek, D Bridgwater, J.L Boak
1980 Rapport Grønlands Geologiske Undersøgelse  
A 1.5-2 m wide fine-grained undeformed acid dyke, cutting the Early Archaean Isua supracrustal succession, was found in 1978 (D.B., J.B.). Preliminary Rb-Sr isotope measurements (F.K.) of small hand samples suggested an unexpected mid-Proterozoic age. Additional material was collected in 1979 (J.B.). Owing to weight restrictions in the helicopter, some of the samples are smaller (100-500 g) than we would normally use, but we feel justified in presenting the results since they suggest
more » ... suggest Proterozoic granitic activity in the area, which has implications for the later history of the Archaean block.
doi:10.34194/rapggu.v100.7702 fatcat:uanskgg6p5gllmtoulvfjzooxu