Plate tectonic model based on greenstone geochemistry in the late precambrian - lower palaeozoic sequence in the Solund-Stavfjorden areas, West Norway

A plate tectonic model for the Caledonian eugeosynclinal sequence in the Solund and Stavfjorden districts of west Norway has been based on greenstone geochemistry, sediment deposition, and structural pattems. The thick metabasalts at the base of the sequence are geochemically similar to modem ocean floor tholeiitic basalts, and relate to the late Precambrian - Cambrian opening of the lapetus ocean. Contemporaneously with the formation of oceanic crust, thick piles of sediments accumulated on an Atlantic-type margin to the Baltic continent. During the closing of lapetus an ensimatic island are was formed upon the wedge of earlier sediments, and basic Javas of tholeiitic, calc-alkali, and alkaline affinities were successively erupted. Steepening of an easterly dipping Benioff zone with time, and associated back-are spreading, is the interpretation of the spatiallcompositional relationships of the plate-margin Javas and the Upper Ordovician tectonic evolution including uplift, thrusting, and subsequent redeposition of the pre-existing sequence.