Geological Magazine · 1991 · 67 citations · 32 references
Natural SciencesEarth SciencesGeologyGeoarchaeologyPaleoclimatologyStratigraphyBasin EvolutionGeoarchaeological DatingSeafloor SpreadingVolcanic DepositsVolcanic PetrologyVolcanic RocksBack-arc BasinsBack-arc ExtensionBack-arc SpreadingContinental Margin SedimentationMagmatic Trace Element GeochemistryMarginal Basin EvolutionOphiolite GeochemistryPillow Lava Formation
Abstract The Sulitjelma Gabbro in the central Norwegian Caledonides has been dated with the U/Pb zircon/sphene method to 437±2 Ma. Geological relationships as well as trace-element geochemistry and Nd and Sr isotopic compositions suggest that the gabbro and associated dyke swarms and pillow lava formed during the initial stages of back-arc spreading. The age constrains the timing of juxtaposition of an older island-arc terrane and continental-margin lithologies exposed within the Caledonian nappes. The age of the gabbro is similar to that of the Solund–Stavfjord Ophiolite in west Norway, and confirms that spreading-related magmatism and marginal-basin development took place along the margin of Iapetus in late Ordovician–early Silurian times.
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