Elsevier

Ore Geology Reviews

Volume 135, August 2021, 104223
Ore Geology Reviews

Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden

https://doi.org/10.1016/j.oregeorev.2021.104223Get rights and content
Under a Creative Commons license
open access

Highlights

  • Three sphalerite types characterized by distinct Mn/Fe ratio and trace element trends.

  • Different pyrite generations defined by varying Co concentration and morphology.

  • Re-distribution of fluid mobile elements (e.g., As, Cu, Zn, Pb, Ag, and Au).

  • Silver-rich veins formed through remobilization during ductile–brittle deformation.

  • Trace elements in sulfides similar with other metamorphosed syn-volcanic sulfide ores.

Abstract

Qualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of ‘ball ore’ or ‘durchbewegung’ textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district.

Keywords

Bergslagen
Remobilization
Sphalerite
Pyrite
Silver
LA-ICP-MS

Cited by (0)