![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
Abstract
A Rb-Sr whole rock isochron for late tectonic granitic dykes intruding the high-grade Rödingsfjället Nappe in the Scandinavian Caledonides gives an age of 447±7 Ma and an initial 87Sr/86Sr ratio of 0.7060±0.0004 (87Rb decay constant λ = 1.42 × 10−11a−1). The dykes cut the regional schistosity in the country rocks and are themselves only locally deformed by later movements. It is suggested that the Ordovician age gives a lower limit for the timing of regional metamorphism in the area. The initial Sr-ratio implies that the magma was probably derived by anatexis of greywackes.