En strukturgeologisk modell för berggrunden i Sarvesvagge-Luottolako-området, Sareks Nationalpark, Lappland

Sammanfattning: The high plateau of Luottolako constitutes a topographical area strongly contrasting from the rugged Sarek Mountains. Older geological maps show that not only the topography, but also the bedrock is different compared to the surrounding massifs. However, the boundaries in the previously publis-hed maps indicate impossible structural models. This work presents a new structural model for the Caledonian allochton of the Sarvesvagge-Luottolako area, and a discussion of its significance for the geological development of the area. Four ectonostratigraphical units constitute the bedrock of the area; the Akkajaure Nappe Complex (ANC), belonging to the shortened margin of continent Baltica (TSMB); the Skarja Nappe, Mikka Nappe, and Sarektjåkkå Nappe, all belonging to the Seve-Kalak Superterrane (SKS). The lowermost unit is the ANC, consisting of Precambrian magmatic rocks dominated by syenite, gabbro, and anorthosite. The Skarja Nappe is composed of garnet mica-schist with rare metabasite-boudins. Strongly deformed quartzite with subordinate amphibolite- and retroeclogite boudins constitute the Mikka Nappe. The voluminous Sarektjåkkå Nappe is the uppermost unit, dominated by mafic dykes (70-80%) intruded into riftrelated sediments. The Luottolako Duplex (LD), 20x20 km large, where the units often are small (a few 10´s of m. thick) characterize the study area. The LD is a double duplex structure where all the tectonostratigraphical levels are imbricated. SKS imbricated together with ANC is not recorded from other localities. The imbrication probably developed during the final phase of the Caledonian overthrusting since no metamorphic overprint is recognizable. The syenite-gabbro-anorthosite association of the Luottolako Plateau is the same as the Ruoutevare anorthosite, which can now confidently be correlated with ANC north of Sarek.