none 10.1144/geochem2025-023 Geological Society of London Geological Society of London 1881 187791718 42938 2026071920013600069 10.1144 2026-08-28T14:58:30Z 2025-12-29T11:36:38Z 0 Geochemistry: Exploration, Environment, Analysis GEEA 1467-7873 2041-4943 01 09 2026 02 2026 26 1 Richard D. Dyer Sediment, Soil and Water Geochemical Services, 1268 Martindale Road, Sudbury, Ontario P3E4J5, Canada https://orcid.org/0009-0004-0222-227X A biogeochemistry ( Picea mariana bark) orientation case study consisting of three transects over two known gold zones was completed in the McFaulds Lake region (‘Ring of Fire') located in the far north of Ontario, Canada. The well-known proprietary weak/selective Mobile Metal Ion (MMI TM ) leach with inductively coupled plasma mass spectrometry (ICP-MS) finish was utilized, rather than a conventional technique such as acid digestion and ICP-MS on macerated bark tissue. This approach is based on the need to generate biogeochemical data that more accurately represent the labile phases of elements that may be released from hidden mineral deposits. Extensive peatlands characterize the study area, below which an ∼8 m thick sequence of till covers the underlying Archean bedrock that hosts the Triple J gold zones. The MMI TM results include relevant patterns with respect to the gold zones, in particular for the metals In and Mo. Horizons of massive chromite of the Blackbird deposit also appear to be influencing tree bark biogeochemistry, in particular for Bi, U and rare earth elements. These biogeochemical signals are possible evidence for the presence of a metal accretion zone in the soil substrate, perhaps due to a redox column developed above the mineralized zones. Peat thickness appears to affect metals concentrations in bark tissue; I infer that mineral soil substrates provide more metal signal for uptake to the spruce trees compared to thicker peat areas, where significant portions of the root systems are within organic peat. Comparison to a nearby aqua-regia digest bark geochemistry dataset helps illustrate that landscape drainage and soil/substrate moisture content present additional variables, which can have significant control on the uptake and translocation of some metals to the outer tissues of spruce trees. Using a weak or selective leach technique on black spruce outer bark may improve the signal-to-noise ratio compared to conventional digestion methods by targeting any weakly bound labile phases. 02 24 2026 02 2026 geochem2025-023 10.1144/geochem2025-023 1 10.1144/crossmark-policy www.lyellcollection.org true 2025-04-22 2025-10-20 2025-11-02 2026-02-24 https://www.geolsoc.org.uk/publications/lyell-collection/user-license-1-1 https://www.geolsoc.org.uk/publications/lyell-collection/user-license-1-2 10.1144/geochem2025-023 https://www.lyellcollection.org/doi/10.1144/geochem2025-023 https://www.lyellcollection.org/doi/pdf/10.1144/geochem2025-023 https://pubs.geoscienceworld.org/geea/article/26/1/geochem2025-023/723854/black-spruce-picea-mariana-mobile-metal-ion-mmitm Barnett P.J. Yeung K.H. and McCallum J.D. 2013a. Surficial geology of the Lansdowne House area northwest northern Ontario. Ontario Geological Survey Preliminary Map P.3696 scale 1:100 000. Barnett P.J. 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Manitoba Industry Trade and Mines Geological Survey Open File Report OF2000-4. 10.1144/1467-7873/03-044 10.1144/1467-787302-040 10.1144/1467-7873/07-133 10.1111/gcb.14903 10.34133/remotesensing.0093 Geological Survey of Canada, Bulletin Thorleifson L.H. 442 1993 Quaternary stratigraphy of the Severn and Winisk drainage basins, northern Ontario Thorleifson, L.H., Wyatt, P.H. and Warman, T.A. 1993. Quaternary stratigraphy of the Severn and Winisk drainage basins, northern Ontario. Geological Survey of Canada, Bulletin, 442. van Geffen P.W.G. 2011. Geochemical Indicators of Buried Sulphide Mineralisation Under Sedimentary Cover Near Talbot Lake Manitoba. PhD thesis submitted to the Department of Geological Sciences and Geological Engineering Queen's University. 10.1144/1467-7873/11-RA-066