Geochemical evidence for a rift-related origin of metadolerites within the Senja Nappe, Troms, North Norwegian Caledonides

Metadolerites transecting platform-related to miogeoclinal metasedimentary rocks of the Senja Nappe in Troms, North Norwegian Caledonides, are little altered and reftect primary magmatic characteristics. They show the geochemical signature of a tholeiitic spreading ridge (MORB) basalt, which is transitional between 'within plate' and 'plate margin' basalt, based on major and trace element concentrations. The geochemistry, nature of the host rocks, and structural position in the nappe pile suggest a correlation of the Senja Nappe metadolerites with metadolerites of the late Ordovician/Silurian Balsfjord Group of the Lyngen Nappe (Upper Allochthon), generated during an episode of post-Finnmarkian crustal extension.