Trace element geochemistry of apatite from the Per Geijer ores in the Kiruna area, northern Norrbotten, Sweden
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Due to the many iron and/or copper-gold deposits in northern Sweden the geology has been well documented and also studied from several academic angles, mostly with focus on mineral extraction of those three main commodities. The four investigated apatite iron oxide (AIO) deposits, Rektorn, Henry, Nukutusvaara and the deep part of Rektorn (“Lappmalmen”), are located north of Kiruna town and the original Kiirunavaara AIO-ore, and previous detailed research on these “Per Geijer ores” is limited despite extraction having taken place on most of them.This study seeks to investigate the trace element composition of the apatite occurring as a gangue mineral to the iron oxides in the four mentioned deposits, with particular focus on comparison to other AIO-deposits in the world via the discrimination plots produced by Belousova et al. (2002) as well as the rare-earth element (REE) contents and trends. The main goal is to provide a small pilot study of the REE distributions and whether the REE’s might be worth investigating for by- or co-product extraction to iron and/or phosphorus in the future.Apatite grains were separated using standardized methods, electron probe microanalysis was used to measure the main elements while laser ablation inductively coupled plasma mass spectrometry was used to measure the trace elements. Monazite inclusions were avoided in order to find the apatite-bound contents.The apatites are all very clearly flourapatites, and most major and minor element concentrations in all four deposits are within the expected values of iron-oxide related apatite. Vanadium, nickel, copper, zinc, thorium and uranium values from all studied locations are lower than in other AIO deposits. Zirconium in Rektorn and Nukutusvaara samples are higher than worldwide, and Si values are also slightly elevated.There are potentially four different populations of REE enrichment mixed up in the sampled locations that could possibly be traced to separate tectonic events in an in depth study. The REE’s are LREE-enriched in all sampled locations, most strongly in the Nukutusvaara and Henry ores and the Nukutusvaara footwall. The total REE content is also the highest in these three locations, approaching 1wt% in the apatite itself (i.e. not including REE’s held in monazite inclusions), which could be of use in economic evaluations of the deposits.
Place, publisher, year, edition, pages
2016. , 54 p.
Teknik, Apatit, Per Geijer, REE, sällsynta jordartsmetaller, apatitjärnmalm
IdentifiersURN: urn:nbn:se:ltu:diva-48244Local ID: 5b6e7fb1-dbac-4abb-8caa-6996f6c9dc77OAI: oai:DiVA.org:ltu-48244DiVA: diva2:1021584
Subject / course
Student thesis, at least 30 credits
Natural Resources Engineering, master's
Validerat; 20160527 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved