U-Pb Age, Setting and Tectonic Significance of the Anorthosite-Mangerite-Charnockite-Granite Suite, Lofoten-Vesteralen, Norway

Mangerites, charnockites, anorthosites, gabbros and granitesoccur within a high-grade metamorphic complex in the Lofoten–Vesterålenislands of northern Norway. U–Pb dating of zircon, titaniteand monazite indicates a three-stage magmatic history beginningat 1870–1860 Ma with the emplacement of the Lødingenand Hopen plutons, followed by a dominant stage at 1800–1790Ma that formed the bulk of the suite, and concluded by the emplacementof pegmatites, local rehydration and retrogression between 1790and 1770 Ma. On the scale of the Baltic Shield the 1870–1860Ma episode corresponds to contraction, amalgamation of arcs,and regional deformation. By contrast, the episode at 1800–1790Ma was characterized by major shifts in plate convergence, byintraplate deformation, and by a diversity of magmatic associationsincluding suites derived from the subcontinental mantle andwidespread granitoid rocks extracted from the continental crust.The diversity of concurrent magmatic events across the Svecofennianorogen, and the temporal coincidence with collisional eventsin coeval orogenic belts, suggests that the genesis of the suiteof magmatic rocks may have been related to tectonically drivenmechanisms of magma generation. KEY WORDS: anorthosite–mangerite–charnockite–granite; lithospheric processes; Lofoten–Vesterålen; Svecofennian orogen; U–Pb geochronology