Tourmaline from thirteen volcanogenic massive sulfide (VMS) deposits, three clastic-dominated (CD) Zn Pb deposits, and four barren sediment-hosted tourmalinites were analyzed for major, minor, and trace elements to identify chemical criteria that distinguish tourmaline in VMS and CD deposits from other barren and mineralized environments. Tourmaline from VMS is mainly dravitic, with some deposits showing schorlitic and uvitic compositions, whereas CD Zn Pb and barren tourmalinite tourmaline spans the schorl-dravite transition and dravitic compositions, with few exceptions showing uvitic and foititic compositions. Tourmaline major element composition from VMS and CD is governed by heterovalent coupled substitutions, reflecting local processes specific to each deposit. In barren tourmalinites, the compositions are mainly controlled by the chemical composition of the host metasedimentary units. The VMS tourmaline shows higher Al, Mg, and V, whereas CD has higher Ca, Co, K, Mn, Li, La, Ce, Eu, Zn, and Pb; tourmalinites show higher Fe, Na, Ti, Sr, Cr, Sc, Sn, Ga, and Cu. A partial least-squares discriminant analysis (PLS-DA) model is used to classify VMS deposits, CD Zn Pb deposits, and barren tourmalinites. The results show that VMS tourmaline correlates with Mg, Sn, Ga, and V; CD Zn Pb tourmaline correlates with Pb, Zn, K, Mn, and Eu; and tourmaline from barren tourmalinites correlates with Fe, Ti, and Sr. These elements were used to build bivariate classification plots using element ratios that enhance the geochemical distinction of VMS and CD Zn Pb tourmaline from tourmaline in granite-related Sn W, orogenic gold, porphyry Cu-Mo-Au, iron oxide‑copper‑gold, and barren geological environments. • Chemical data of tourmaline from VMS, CD Zn Pb, and tourmalinites are reported. • Tourmaline composition from VMS, CD Zn Pb, and tourmalinites is compared. • PLS-DA using tourmaline chemistry is used to classify the investigated deposits. • Element ratios are used to discriminate VMS and CD Zn Pb from other deposits types.

Geochemical prospecting serves as a fundamental approach for examining the influence of geological settings on stream sediment composition and identifying natural or anthropogenic geochemical anomalies within a river catchment. Various indices have been developed to assess sediment quality and environmental status, typically based on ratios between observed element concentrations and reference values representing undisturbed conditions. However, these reference values often fail to account for the influence of river dynamics on sediment variability, potentially compromising the reliability of contamination assessments. Since the chemical composition of stream sediments reflects the cumulative influence of their upstream catchment basins, the dilution correction method has been extensively employed in previous studies to mitigate the dilution effects caused by fluvial processes. To address this, the present study evaluates whether local geochemical baselines can improve the performance of contamination indices. The Sarno River basin, heavily impacted by urban and industrial activities, was selected as a case study. Ninety-six sediment samples were analysed using geomorphological and hydrological parameters to define each Sample Catchment Basin (SCB). Baseline concentrations of Cd, Cr, Cu, Hg, Ni, Pb, Sb, and Zn were then estimated by calculating the weighted average element content based on lithological unit proportions within each SCB. Then, contamination indices were computed using both uncorrected (raw) and SCB-corrected baselines and spatially mapped. The use of SCB-based reference values led to a 23 % increase in the detection of high-impact sites using the Enrichment Factor and a 366 % increase using the Contamination Factor, revealing a substantial underestimation of contamination in the raw approach. Comparative analysis also showed a more balanced distribution of element contributions in the corrected indices, indicating improved representativeness of multi-element contamination. These results highlight the advantages of incorporating local baseline variability into geochemical evaluations, providing a more accurate and spatially consistent framework for environmental risk assessment in fluvial systems. • The Sarno River basin was divided into Sample Catchment Basins to assess contamination. • SCBs calculate local baseline values using weighted averages of lithological units. • Local baselines improve the contamination index accuracy over traditional methods. • Local baselines identify better anthropogenic sources, especially in downstream areas. • Sensitivity analysis shows local baseline method reduces bias in contamination assessment.

The Rävliden North volcanogenic massive sulfide (VMS) deposit, in northern Sweden underwent polyphase deformation and greenschist to lower amphibolite facies metamorphism during the Svecokarelian orogeny. This caused remobilisation and recrystallisation of ore minerals, whose composition was analysed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA). Sphalerite, chalcopyrite, and pyrrhotite chemistry mirrors zonation of undeformed VMS deposits. Chalcopyrite-rich mineralisation contains higher Cu, Co, In, and lower Mn concentrations than sphalerite-rich mineralisation. Besides galena, Ag occurs in sulfosalts, tellurides, antimonides, and amalgams, which possibly formed through exsolutions from α-galena in syn - to post-tectonic structures. LA-ICP-MS imaging shows Ag-rich minerals in early syngenetic pyrite, in contrast to syn-metamorphic pyrite, indicating remobilisation during deformation. Despite sampling effects accounted for through linear mixed effects (LME) modelling, the results indicate that syn -metamorphic recrystallisation and remobilisation did not lead to substantial compositional changes in ore minerals. Instead, these processes partitioned Ga between sphalerite and chalcopyrite and enriched Ag, Cd, and Sb in minerals associated with younger parageneses. Zeolite-bearing veins in the hanging wall host sphalerite with the highest Ga, Ge, Cu, and Sb contents and galena with the lowest Bi, Te, and Tl contents. An origin potentially linked to far-field effects of the opening of the Iapetus Ocean or waning Timanian orogeny is discussed based on similarities to other vein- and breccia-hosted Zn Pb deposits in Northern Sweden. This study provides the first multiple-mineral in-situ trace element dataset for a VMS deposit in the Skellefte district, enhances understanding of element redistribution during metamorphism, and identifies remobilised elements potentially vectoring mineralisation at depth. Moreover, this study enables tracing of penalty and by-product elements in downstream beneficiation processes. • Redistribution of Ag, Cu, Co, Cd, Ga, Ge, In, Mn, Ni, Sb among co-existing sulfides • Recrystallisation enriched Ag, Sb, and Cd in syn-metamorphic minerals. • Post-Svecokarelian veins in the hanging wall host sphalerite with high Ga, Ge, Cu, and Sb. • Sulfide chemistry mirrors metal zonation seen in undeformed VMS deposits. • Mineralisation in hanging wall helps vector deposits at depth in the Skellefte district.