Pillow lavas as protoliths for eclogites: evidence from a late Precambrian-Cambrian continental margin, Seve Nappes, Scandinavian Caledonides

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

“…There is widespread evidence for a substantially cooler metamorphic history here than in the Vaimok Lens. Paragonite is part of the prograde paragenesis, and preservation of growth zoning in garnet is the norm (this study ;Nicholson 1984;Kullerud et al 1990;Stephens and van Roermund 1984). Additionally, one Upper Tsäkkok eclogite contains low-T glaucophane and crossite, interpreted by Stephens and van Roermund (1984) as having crystallized during uplift from peak eclogite-facies conditions.…”

“…The Upper Tsäkkok is mainly marble, quartzite, and garnet-phengite schist, with abundant eclogite and amphibolite. Locally, within the Upper Tsäkkok, eclogite protoliths are demonstrably pillow lavas preserving primary contacts with the host schists (Kullerud et al 1990). There is widespread evidence for a substantially cooler metamorphic history here than in the Vaimok Lens.…”

“…A sample of eclogitized pillow basalt was taken from the Upper Tsäkkok Lens in the outcrop described by Kullerud et al (1990) (Fig. 2).…”

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

“…In contrast to the Western Gneiss Complex, it has been demonstrated that the SNC has been emplaced far eastwards over the Baltoscandian margin, including the foreland basin and platform sediments that now occur in the lower nappes and underlying autochthon (Gee, 1975). These "foreland" eclogites were subsequently found to be relatively widespread in the SNC (Van Roermund, 1982;Van Roermund and Bakker, 1983;Andréasson et al, 1985;Van Roermund, 1985;Kullerud et al, 1990). It has been inferred that they were generated during Ordovician subduction of the Baltoscandian continental margin (Dallmeyer and Gee, 1986;Mørk et al, 1988;Andréasson, 1994;Brueckner andVan Roermund, 2004, 2007), i.e.…”

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

“…Whereas some of the Seve Nappes have been subducted and educted, others were not. And one particular unit, including pillow basalts, provides evidence of LT/HP metamorphism, with glaucophane in association with eclogites (Kullerud et al, 1990).…”