Diachronous burial and exhumation of a single tectonic unit during collisional orogenesis (Sulitjelma, Arctic Scandinavian Caledonides)

• Main Authors: Boyle, A.P., Burton, Kevin W., Westhead, R. Keith
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Geological Society of America 1994
• Subjects: Earth Sciences; Arctic; Sulitjelma
• Online Access: http://nora.nerc.ac.uk/id/eprint/9079/; http://geology.geoscienceworld.org/content/vol22/issue11/

The Sulitjelma fold nappe represents part of a Caledonian marginal basin obducted during the closure of the Iapetus Ocean and collision between Laurentia and Baltica. Metamorphic pressure-temperature (P-T) paths indicate that various parts of the Sulitjelma fold nappe followed characteristic clockwise P-T paths involving prograde burial followed by prograde exhumation and then near-isothermal exhumation prior to cooling. Geochronological results indicate that foreland rocks followed this general P-T path before more hinterlandward rocks, such that foreland rocks underwent exhumation while hinterlandward rocks were still being buried. This is consistent with the fold nappe passing through a collisional orogen; burial and ultimately prograde metamorphism were terminated sequentially by exhumation as a given part of the fold nappe came into contact with the lower plate, basement ramp (Baltica) and was driven upward. Burial, heating, exhumation, and cooling were thus diachronous within a single tectonic unit.