U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden

Energy Drive for the Kiruna Mining District Mineral System(s): Insights from U-Pb Zircon Geochronology

“…1.88-1.86 Ga [28,93], Figure 3). This age, together with a recent age determination by Andersson et al [22] on a volcanic intercalation in the Kurravaara conglomerate (1887 ± 3 Ma), mark the earliest Orosirian volcanic activity determined in the Kiruna district.…”

“…1.90 Ga, early NE-directed subduction and back-arc extension in northern Norrbotten commenced, followed by the accretion of the Skellefte volcanic arc in the south onto the Archean craton to the north (termed D 1 in Norrbotten, but D 2 in the Skellefte district and Överkalix lithotectonic unit; Figure 1, [31,46,51,52]). Recent geochronologicalstructural investigations have shown that the timing of early back-arc extension, volcanism, and associated synvolcanic faulting can be bracketed within 1887 ± 3 Ma (syn-basin deposition volcanic, U-Pb zircon; [22]) to a least ca. 1874 ± 9 Ma in the Kiruna area (age of the hanging wall of the Rektor deposit, U-Pb zircon; [28]).…”

“…However, a direct geochronological constraint on deformation has recently been obtained on syntectonic titanite (U-Pb LA-ICP-MS) approximately 5 km east of the Kiruna district, which indicates the hosting shear zone was active around 1812 Ma during an event lasting up to 20 m.y. [22].…”

“…However, K-bearing alteration is also observed related to early Svecokarelian ore-forming events (e.g., Rakkurijärvi, Per Geijer iron ores; [5,26]). In addition, radiometric dating suggests that a late sodic-calcic alteration style also developed during D 2 [22], implying that the hydrothermal alteration associated to the early-and late-cycle tectonomagmatic events in Norrbotten was of similar character, complicating the usage of mineral parageneses as vectors toward specific ore deposits.…”

“…An added element of complexity to the mineral systems approach occurs in regions with long and complicated tectonic histories, such as the Norrbotten province, which has experienced several phases of extension and deformation resulting in compound structural patterns and overprinting magmatic and metamorphic events (cf. [2,5,[18][19][20][21][22]). Furthermore, the landscape has been shaped by Quaternary glaciation leaving extensive till coverage and poor outcrop exposure.…”