FISSION-TRACK AND K-AR DATING OF TECTONIC ACTIVITY IN A TRANSECT ACROSS THE MORE-TRONDELAG FAULT ZONE, CENTRAL NORWAY

Fission-track dating of apatite, zircon and sphene, and K-Ar dating of K-feldspars in samples taken from a transect across the More-Trondela g Fault Zone in Trondelag confirm the long-lived nature claimed for th is complex fault zone. Apatite, zircon and sphene, which have blocking temperatures of 125-degrees +/- 25-degrees-C, 200-degrees +/- 50-degr ees-C and 250-degrees +/- 50-degrees-C, respectively, together indicat e a complex history of post-Caledonian tectonism. Uplift and cooling a re indicated in Early Palaeozoic (Late Ordovician-Early Carboniferous) and Triassic-Jurassic times, with erosion of at least 3 km of Early a nd possibly Late Palaeozoic supracrustal cover since the Late Palaeozo ic. Late Jurassic activity is indicated along the Verran Fault.