Preliminary Rb-Sr isotope evidence on the age and metamorphic history of the North Greenland crystalline basement

Abstract

No outcrops of crystalline basement rocks are known in the eastem part of North Greenland, mapped in 1978 and 1979 by the Geological Survey of Greenland. The oldest rocks are sandstones of the Proterozoic Independence Fjord Group (Collinson, this report). However, ice-transported boulders of gneisses, amphibolites and granitic rocks indicate the presence of crystalline rocks under the Inland Ice, perhaps not far south of the ice margin (fig. 46). The nearest outcrops of crystalline basement in North Greenland occur at the head of Victoria Fjord, c. 250 km west of Independence Fjord (Hurst & Peel, 1979). These rocks have as yet not been mapped or studied.