A Late Ordovician U?Pb age for the Troms? Nappe eclogites, Uppermost Allochthon of the Scandinavian Caledonides

U–Pb geochronology of two discrete Ordovician high-pressure metamorphic events in the Seve Nappe Complex, Scandinavian Caledonides

“…In contrast, 452 Ma eclogite formation in the Tromsø Nappe in the Uppermost Allochthon ( Fig. 1) took place on the margin of Laurentia, prior to its approach toward Baltica during closure of Iapetus (Corfu et al 2003). The Jaeren Nappe in SW Norway (Fig.…”

UHP metamorphism recorded by kyanite-bearing eclogite in the Seve Nappe Complex of northern Jämtland, Swedish Caledonides

“…Eclogites of similar age to the eclogites in the SNC of Jämtland occur also in the Jaeren Nappe of southwestern Norway (ca. 470-455 Ma; Smit et al, 2010) and in the Tromsø Nappe of northern Norway (452 Ma; Corfu et al, 2003). The Tromsø Nappe, which also includes UHP eclogites (Ravna and Roux, 2006;Janák et al, 2012), may be a northwestwards continuation of the high-grade units equivalent to the SNC in the Caledonides of northern Norway.…”

Magmatism and early-Variscan continental subduction in the northern Gondwana margin recorded in zircons from the basal units of Galicia, NW Spain

“…The U-Pb age of metamorphic zircons from eclogite is commonly interpreted as a good approximation of the age of the eclogitic metamorphism (e.g., Rubatto et al, 1999;Corfu et al, 2003b;Baldwin et al, 2004), which is probably true in most cases, but not necessarily always. The interpretation of U-Pb ages in eclogites as the time of peak of high-P metamorphism should be taken with caution, because in some cases (as demonstrated here) zircon may represent post-eclogitic growth, even in low-to on January 29, 2010 gsabulletin.gsapubs.org Downloaded from medium-temperature terranes.…”