PETROGRAPHIC EVIDENCE FOR DIACHRONOUS METAMORPHISM OF THE SKAITI SUPERGROUP, KOLI-NAPPE COMPLEX, ARCTIC SCANDINAVIAN CALEDONIDES

The Skaiti Supergroup is the upper most major tectono-stratigraphic un it of the Koli Nappe Complex, which comprises Precambrian to Lower Pal aeozoic rocks immediately north of the Arctic Circle in Scandinavia. T his complex was derived from within the Iapetus Ocean and emplaced dur ing the Scandian phase of the Caledonian Orogeny. Petrographic evidenc e along a hinterland to foreland transverse of the Skaiti Supergroup d emonstrates that garnet, staurolite, and kyanite porphyroblastesis was diachronous with respect to fabric development, becoming later toward s the hinterland. The hinterland rocks experienced two discrete phases of heating, whereas the foreland rocks only experienced one. These ob servations are consistent with a recent tectonic model for diachronous burial and exhumation of the Koli Nappe Complex during emplacement.