Textural and chemical characterization of sulphide minerals for improved beneficiation and exploration at the Rävliden Norra VMS deposit, Skelleftedistrict, Sweden

The 34th Nordic Geological Winter Meeting

Document identifier: oai:DiVA.org:ltu-77301
Keyword: Natural Sciences, Earth and Related Environmental Sciences, Geology, Naturvetenskap, Geovetenskap och miljövetenskap, Geologi, Ore Geology, Malmgeologi
Publication year: 2020
Abstract:

The Rävliden Norra VMS deposit, represents one of the most important new discoveries in the Skellefte district (SD) in this decade. The mineralization is hosted at the transition between Skellefte group rocks (SG), dominated by coherent rhyolitic and dacitic meta-volcanic rocks, and the Vargfors group (VG), composed of metasedimentary graphitic shale interbedded with crystal-rich, monomictic to polymictic, clast-supported mass flow deposits. The ore lenses contain massive sphalerite + galena + pyrite + pyrrhotite + chalcopyrite ± Ag-Sb-Pbsulphosalts, structurally and stratigraphically above chalcopyrite + pyrrhotite stringer mineralization. The hanging wall rocks (VG) host pyrite + pyrrhotite ± arsenopyrite mineralization. Alteration in the footwall rocks, consists of sericite, chlorite, quartz, pyrite, tremolite, actinolite, carbonate and talc. The hanging wall is less altered with limited sericite or chlorite associated with minor carbonate alteration. Post ore modifications occur as, e.g. sulphides in pressure shadows, infilling of syntectonic tension gashes, “durchbewegung” texture, and sulphide-rich veins that crosscut hanging wall rocks. Significant changes in the distribution and deportment of trace and precious elements within the deposit are evident, however the implications of these on mineral processing performance and exploration vectoring has not previously been assessed in other VMS deposits in the SD. To this end, the presence of pyrite and remobilised sulphides in both hanging wall and footwall of the Rävliden Norra mineralizations, provides an opportunity to evaluate enrichment or depletion of elements hosted in the sulphide lattices or as inclusions using LA-ICP-MS. In-situ SIMS analyses in sulphide phases will allow discrimination between sedimentary and hydrothermal sulphur in the system. An investigation into the deportment of In, Ga and Ge in sphalerite and galena, will be the first assessment of these critical elements in a VMS deposit in the SD. Ultimately, integration of elemental distribution and mineral features, such as modal mineralogy, liberation degree, and grain size, with processing variables, e.g. mineral recovery, grade or flotation kinetics; will provide a better understanding of the ore performance during concentration and beneficiation.

Authors

Jonathan Rincon

Luleå tekniska universitet; Geovetenskap och miljöteknik
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Nils Jansson

Luleå tekniska universitet; Geovetenskap och miljöteknik
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C. Kaiser

Boliden Mineral AB, Exploration department, Boliden, Sweden
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Helen Thomas

Luleå tekniska universitet; Geovetenskap och miljöteknik
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Christina Wanhainen

Luleå tekniska universitet; Geovetenskap och miljöteknik
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M. Persson

Boliden Mineral AB, Exploration department, Boliden, Sweden
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