Abstract
A geochemical study of the low-grade Seve amphibolites from Mt. Sylarna indicates that they have an affinity to abyssal, tholeiitic magma. The spilitic character of the amphibolites is emphasized in the interpretation of their magma-tectonic implications. A proposed pre-orogenic relationship between, the underlying Särv tholeiitic dykes and the Seve amphibolites in the Sylarna-Helags area is discussed. It is concluded that a magma-genetic relation may exist, which, however, does not place constraints on the translation distance of the Seve Nappe. A hypothetical model for a comagmatic origin of the Särv dolerites and the Mt. Sylarna amphibolites is proposed, involving early basaltic volcanism in the Iapetus Ocean.