The Kiruna mining district, Sweden, known for the type locality of Kiruna-type iron oxide-apatite (IOA) deposits, also hosts several Cu-mineralized deposits including iron oxide-copper-gold (IOCG), exhalative stratiform Cu-(Fe-Zn), and structurally controlled to stratabound Cu +/- Au. However the relationship between the IOA and Cu-systems has not been contextualized within the regional tectonic evolution. A broader mineral systems approach is taken to assess the timing of energy drive(s) within a regional tectonic framework by conducting U-Pb zircon geochronology on intrusions from areas where Cu-mineralization is spatially proximal. Results unanimously yield U-Pb ages from the early Svecokarelian orogeny (ca. 1923-1867 Ma including age uncertainties), except one sample from the Archean basement (2698 +/- 3 Ma), indicating that a distinct thermal drive from magmatic activity was prominent for the early orogenic phase. A weighted average Pb-207/Pb-206 age of 1877 +/- 10 Ma of an iron-oxide-enriched gabbroic pluton overlaps in age with the Kiirunavaara IOA deposit and is suggested as a candidate for contributing mafic signatures to the IOA ore. The results leave the role of a late energy drive (and subsequent late Cu-mineralization and/or remobilization) ambiguous, despite evidence showing a late regional magmatic-style hydrothermal alteration is present in the district.

As part of the larger mineral systems approach to Cu-bearing mineralization in northern Norrbotten, this study utilizes structural geology to set the classic Pahtohavare Cu ± Au deposits into an up-to-date tectonic framework. The Pahtohavare Cu ± Au deposits, situated only 5 km southwest of the Kiirunavaara world-class iron oxide–apatite (IOA) deposit, have a dubious timing, and their link to IOA formation is not constrained. The study area contains both epigenic Cu ± Au (Pahtohavare) and iron oxide–copper–gold (IOCG; Rakkurijärvi) mineral occurrences which are hosted in bedrock that has been folded and bound by two shear zones trending northeast to southwest and northwest to southeast to the east and southwest, respectively. Structural mapping and petrographic investigation of the area reveal a noncylindrical, SE-plunging anticline. The cleavage measurements mirror the fold geometry, which characterizes the fold as F₂ associated with the late phase of the Svecokarelian orogeny. Porphyroclasts with pressure shadows, mylonitic fabrics, and foliation trails in porphyroblasts indicate S₀/S₁  is a tectonic fabric. The epigenetic Pahtohavare Cu ± Au mineralization sits in brittle–ductile structures that cross-cut an earlier foliation and the F₂ fold, indicating that the timing of the deposits occurred syn- to post-F₂ folding, at least ca. 80 Myr after the Kiirunavaara IOA formation. A 3D model and cross-sections of the Pahtohavare–Rakkurijärvi area and a new structural framework of the district are presented and used to suggest that the shear zones bounding the area are likely reactivated early structures that have played a critical role in ore formation in the Kiruna mining district.

The Kiruna mining district, Sweden, is well known for its many iron oxide-apatite (IOA) deposits (Kiruna-type), but also hosts several Cu-bearing ore bodies of different ages. This includes the Pahtohavare area which hosts both a pre-orogenic stratiform Cu (Fe ± Zn) ore body as well as three late-orogenic epigenetic Cu ± Au deposits. The region has undergone multiple phases of deformation, metasomatism, and mineralization during the Svecokarelian orogeny and the effect of each overprinting event on the sulfur and metal budget of later mineralization events remains unclear. Utilizing the structural framework of the Svecokarelian orogeny, Cu- and Fe-sulfides from the Pahtohavare area are classified based on microstructures into early and late generations, which are subsequently analyzed for in situ δ34S and trace element contents and assessed with Linear Mixed Effects (LME) modelling to test for statistical significance. Results indicate that δ34S values from both the early and late mineralization exhibit a wide range from ca. -26‰ to +6‰. Early sulfur fractionation occurred during biogenic sulfate reduction in a system with excess sulfate forming syn-depositional pyrrhotite with δ34S signatures from ca. -22‰ to -21‰. LME modelling indicates a slightly higher δ34S range (ca. -20‰ to +6‰) is associated with the epigenetic mineralization compared to the pre-orogenic mineralization (ca. -26‰ to -5‰) but overlapping signatures suggest mixing occurred between pre-existing sulfur reservoirs leading to inherited signatures for the late mineralizing event. Similarly, at the pre-orogenic deposit, Co/Ni ratios of pyrrhotite in remobilized textures show a strong overlap with pyrrhotite in syn-depositional textures, indicating a local metal source for remobilized sulfides. Pyrite Co/Ni ratios for the pre-orogenic mineralization are lower (c. 0.1-10) in comparison to the epigenetic mineralization (c. 0.1-100) but a mixing trend is interpreted between the deposits. The late mineralization event is therefore characterized by higher Co contents and δ34S values but mixing trends suggest metals and sulfur were also inherited from pre-existing sulfides.