Major and trace element analysis of common skarn minerals from Långban, Värmland, Sweden

Abstract

The area of Långban, Värmland, is well investigated in terms of the many exotic minerals occurring in the area. In contrast, less focus has been given to the trace element systematics of the commonly occurring skarn-forming minerals. The composition of major and trace elements in rock-forming phases can yield valuable information for understanding various geological events and mineralization processes. Therefore, this study has conducted geochemical analysis on commonly occurring skarn minerals from three different rock samples collected at Långban, Bergslagen. The analysis was performed using techniques such as a Scanning Electron Microscopy (SEM), Raman spectroscopy, and Laser Ablation – Inductively Coupled Plasma – Mass Spectrometer (LA-ICP-MS). Overgrowth zonings have been investigated in these phases to understand the paragenetic sequence of minerals, effects of fluid migration, and the substitution of elements. Results show textural and chemical variations between phases and across different zones. A variation in Eu2+ -anomaly between phases coupled with Mn and Zn concludes the relative age difference between magnesiohastingsite and tremolite in the paragenetic sequence. The enrichment of As, Sb, Bi, Ba, Pb, Zn, and Cu visible in the diopside, along with an Mn-enrichment, suggests a coupling of these. However, the concentration of Pb, Ba, As, Bi, Sb, and Cu in the rim of calcite do not show any coupling with Mn, suggesting several mobilization events of these commonly enriched elements in the Långban area.