Timing and origin of the host rocks to the Malmberget iron oxide-apatite deposit, Sweden

•The MalmbergetIOAdepositis hosted by volcanic rocks intruded by various dikes.•Thevolcanic rocks are dated at 1885 ± 6 Ma and 1881 ± 6 Ma respectively.•Granitic and aplitic dikes are dated at c. 1790 Ma.•Ametamorphicoverprint event in the Gällivare area is dated at 1775 ± 6 Ma.•Geochemical signatures indicate generation in a volcanic arc environment. The northern Norrbotten region in Sweden hosts abundant iron-oxide apatite (IOA) deposits including Kiirunavaara, the type locality for Kiruna-type deposits, and Malmberget. Felsic and intermediate metavolcanic rocks hosting the Malmberget IOA deposit contain oscillatory zoned zircon which yield magmatic U-Pb SIMS ages of 1885 ± 6 Ma and 1881 ± 6 Ma, respectively. Metamorphic rims on zircon from these rocks yield 1797 ± 7 Ma and 1775 ± 6 Ma, respectively, and record the age of the latest Svecofennian regional metamorphic event in the Gällivare area, tentatively interpreted as regional contact metamorphism. Two granite dikes that cut the ore yield U-Pb zircon emplacement ages of 1790 ± 6 Ma and 1791 ± 7 Ma, respectively, overlapping with the metamorphic overgrowths, and set a lower age limit for ore formation in the Malmberget IOA deposit. Rocks hosting the Malmberget IOA deposit have an alkalic to alkali-calcic affinity with a geochemical signature that favors a continental-arc, transitional to extensional setting. These rocks are suggested to have been generated in a back-arc region, in response to subduction beneath the craton margin retreating to the SW or W. The obtained ages and geochemical signatures of these rocks coincide well with the regionally defined Kiirunavaara group rocks, hosting several other IOA deposits in northern Sweden.