New geochronological and Sm–Nd constraints across the Pajala shear zone of northern Fennoscandia: Reactivation of a Paleoproterozoic suture

Geochronology of Hydrothermal Processes Leading to the Formation of the Au–U Mineralization at the Rompas Prospect, Peräpohja Belt, Northern Finland: Application of Paired U–Pb Dating of Uraninite and Re–Os Dating of Molybdenite to the Identification of Multiple Hydrothermal Events in a Metamorphic Terrane

“…In the present setting, the Peräpohja belt is bound by the Archaean Pudasjärvi Complex on the Southeast, the Central Lapland Granitoid Complex on the north, and the Pajala shear zone on the west. The latter structure is considered as the multiply re-activated manifestation of the boundary zone between the Karelian and Norrbotten Archean basement domains [12].…”

“…The 1-2 km thick Paakkola group consists of pillow basalts and felsic dikes (2.05 Ga) [22], mafic and felsic tuffs, graphitic-sulphidic mica schist and black shales. The formations included in the Martimo and Rovaniemi suites/supersuites are part of the Paakkola group and their distinction on Figure 1 is according to [12] who considered these units as lithodemic in nature. Results of U-Pb dating of detrital zircons suggests that the maximum age of the youngest mica schist rocks in the Martimo suite is 1.91 Ga (sample A2167 on Figure 2) [11].…”

“…The formations of the Mellajoki Suite are intruded by thẽ 2.0 Ga Kierovaara granite ( Figure 1). The Svecofennian tectonic evolution of the Peräpohja belt has recently been summarized in [12,13], based on detailed structural mapping in selected areas and revision of available geochronological data for rock-forming minerals. Accordingly, the onset of the first collision stages (e.g., collision between Karelia and Kola, as well as between Norrbotten and Karelia; Figure 1) is probably reflected by a weakly constrained metamorphic event in the Rovaniemi Supersuite between ca.…”

“…Re-Os dating of molybdenite is a particularly robust tool for dating hydrothermal processes because (1) compared to other sulphide minerals, molybdenite is unusually rich in Re, (2) the Os content of molybdenite on crystallization is extremely low, and (3) the Re-Os clock in molybdenite remains intact, even when the mineral is deformed or subjected to granulite facies metamorphic conditions [7][8][9][10]. For the geological interpretation of our U-Pb and Re-Os age data, we also used U-Pb ages for rock forming zircon and Nd-Sm ages for rock forming garnet published in [11], and considered the recently established model for the tectonic evolution of the Peräpohja belt [12,13].…”

Geochronology of the Palaeoproterozoic Kautokeino Greenstone Belt, Finnmark, Norway: Tectonic implications in a Fennoscandia context

“…1; Huhma et al, 1990;Lehtonen et al, 1998;Koistinen et al, 2001;Perttunen & Vaasjoki, 2001;Rastas et al, 2001;Hanski & Huhma, 2005;Ranta et al, 2015). Structurally, the NNW-SSE-trending structures in the Kautokeino Greenstone Belt may link to the N-S-trending Pajala shear zone on the western side of the Central Lapland Greenstone Belt and Peräpohja Schist Belt (Lahtinen et al, 2015a;Ranta et al, 2015). Westwards, the Ráiseatnu Complex is separated from the Norrbotten Craton by discontinuous greenstone belts ( Fig.…”