Few studies have focused on the application of the Tl isotopic system for geochemical exploration. We report ε 205 Tl values of rock samples from the TL Deposit, British Columbia, Canada – a sediment-hosted massive sulfide (SHMS) deposit with characteristics of a Broken Hill-type deposit – and investigate relationships with major and trace element geochemistry. Maps generated using Tl isotope and trace element data indicate that ε 205 Tl values can potentially be used to fingerprint ore mineralization at the TL Deposit. The sources of Tl and other metals (Ag, Pb, Zn) are assessed using Tl isotope data. Measured ε 205 Tl values exhibit positive correlations with Pb, sedimentary exhalative metal index (Zn + 100*Pb + 100*Tl), and the redox proxy, U/Th, and negative correlations with Be, Cd, Ce, La, Ni and Th. Individual lithologies have distinct Tl isotopic compositions. Metal-rich heavily altered samples have relatively high ε 205 Tl values (−5.0 to −2.5 ε -units) reflecting the euxinic conditions of the global Paleoproterozoic ocean and hydrothermal influence. Samples with lower ε 205 Tl values (−15 to −7.6 ε -units) reflect a combination of their mineralogy (phyllosilicate minerals such as biotite and clinochlore), Tl from sediments reflecting the Tl isotopic composition of modern seawater, and possible low-temperature alteration processes. Samples with high Pb and Ag contents have high ε 205 Tl values, indicating a hydrothermal origin of these metals, whereas Zn is highest in samples with low ε 205 Tl values, indicating a low-temperature or sedimentary origin. Thallium isotopes, paired with conventional geochemical data, show promise as a useful tool for exploration of SHMS deposits with Broken Hill-type characteristics. Supplementary material: Major, minor and trace element contents of samples and reference materials, blank values, correlation coefficient values, and XRD patterns are available at https://doi.org/10.6084/m9.figshare.c.6370671 Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits

Biogeochemical orientation surveys were undertaken at low sulphidation epithermal Au–Ag occurrences in the Hauraki Goldfield–Coromandel Volcanic Zone and the Taupo Volcanic Zone, and at the Waiotapu active geothermal area in the Taupo Volcanic Zone. Several plant species were sampled, including the foliage of tree ferns and tea trees. The ferns – silver fern ( ponga ), rough tree fern ( wheki ) and black tree fern ( mamaku ) – were ubiquitous and were the easiest species to sample, although tea tree was the dominant genus at Waiotapu. At the Waiotapu geothermal area, significantly higher concentrations of Ag, Au, Sb, As, Cs and Rb were present in samples close to Champagne Pool than elsewhere, confirming its location as the main outflow source of Au, Ag and their pathfinder elements. The fern survey areas at Luck at Last mine, Pine Sinter and Ohui in the Coromandel Volcanic Zone each exhibited biogeochemical anomalies, which successfully highlighted most of the known quartz veins and provided additional anomalies for further investigation. Rough tree fern was the most common species at Goldmine Hill, Puhipuhi (Taupo Volcanic Zone). Although this species absorbs lower concentrations of many elements than the silver fern, the spatial distribution of elements is of greater significance than their absolute concentrations. The highest Au, Ag, As and Al concentrations occurred in samples from a ridge extending WNW from Goldmine Hill. Sb and Bi were at anomalous levels in an area peripheral to the precious metal anomalies, indicating the potential zonation of elements distal from the Au and Ag deposits. Supplementary material: The full datasets on the fern and tea tree chemistry, including quality assurance/quality control and multi-element plots, are available free of charge through the GNS Science website (search for Dunn) at http://shop.gns.cri.nz/publications/science-reports/ .

Biogeochemical orientation surveys were undertaken at epithermal Au-Ag deposits in the Coromandel Volcanic Zone - Hauraki Goldfield (CVZ) and Taupo Volcanic Zone (TVZ), and at the Waiotapu geothermal area in the TVZ. Several plant types were sampled including pine tree bark and needles, tree fern fronds and tea tree foliage. The ferns had the most consistent occurrence and were easiest to sample, although tea tree was the main sample medium at Waiotapu. Sampling at the three CVZ Au-Ag prospects, Luck at Last, Pine Sinter and Ohui, was on previous soil geochemistry grids. The biogeochemical element anomalies successfully highlighted most known quartz veins and provided additional anomalies for further investigation. The latter were in many cases not spatially coincident with similar soil geochemical anomalies and these spatial differences are attributed to deeper penetration by the plants or soil creep downslope. At the Goldmine Hill Au-Ag prospect in the TVZ, highest Au, Ag, As and Al in ferns correlated well with the elevated Hg reported previously in soils from this area and with anomalies of pathfinder elements in reconnaissance rock chip geochemistry. At the Waiotapu geothermal area, significantly higher concentrations of Ag, Au, Sb, As, Cs and Rb were present in samples close to Champagne Pool than elsewhere confirming its location as the main outflow source of precious metals and their pathfinder elements.

Recommended citation: Bluemel, B., Dunn, C., Hart, C., and Leijd, M., 2015. Biogeochemical expressions of buried REE mineralization at Norra Kärr, southern Sweden. In: Simandl, G.J. and Neetz, M., (Eds.), Symposium on Strategic and Critical Materials Proceedings, November 13-14, 2015, Victoria, British Columbia. British Columbia Ministry of Energy and Mines, British Columbia Geological Survey Paper 2015-3, pp. 231-239.

Glacial deposits, dense vegetation and rugged terrain pose challenges to conventional mineral exploration in the Mabel Lake area of southern British Columbia, where metamorphosed schists, quartzites and calcareous rocks of the Monashee sequence are known to host significant Pb-Zn deposits such as Kingfisher and Ruddock Creek. In 2006, the Geological Survey of Canada conducted a reconnaissance tree-top sampling programme to provide a biogeochemical dataset for c . 700 km 2 of this region. Douglas-fir tree-top samples from 562 sample stations were collected from a helicopter, and analysis of the tissues indicated several Tl and Cd anomalies. Detailed follow-up sampling east of Mabel Lake using western hemlock bark confirmed a Tl anomaly extending c . 600 × 600 m. Data from these surveys were published but received little attention for several years until the area surrounding the main Tl anomaly was staked and detailed exploration commenced. Ah soil horizon sampling within the Tl anomaly identified multi-element anomalies including high concentrations of Mo and Zn. Indicator minerals from a few stream sediments included gahnite and goldmanite providing further evidence for the presence of base metal mineralization. Follow-up work that involved 391 m of excavations along 3 parallel trenches revealed a gossan-rich zone, 10–35 m wide and >50 m long with best concentrations of 8.98% Zn (over 3 m); 580 ppb Re; 1339 ppm Mo, and anomalous concentrations of Cd, Cu, Bi, Ni, Pb, Sn, Tl, V and W. Subsequently, a HeliTEM® electromagnetic survey was flown over c . 12 km 2 of the contiguous claims and a small drilling programme has intersected Zn-rich massive sulphide. This grassroots study demonstrates the evolution of an exploration programme that started with a chronological order of: (a) reconnaissance biogeochemical survey; (b) detailed biogeochemistry; (c) Ah soil horizon geochemistry; (d) indicator mineral stream sediment survey; (e) trenching; (f) airborne geophysics; and (g) drilling that has identified significant base metal mineralization.

The Palaeoproterozoic Granites–Tanami Province in Western Australia and the Northern Territory contains numerous significant gold deposits, but recent exploration for additional deposits has been hampered by deep weathering of the basement and extensive Tertiary and Quaternary cover. Biogeochemical exploration has rarely been attempted in this environment, with soil sampling and drilling being the principal exploration methods. This paper outlines the methodology and results of a biogeochemical exploration programme utilizing Triodia pungens (soft spinifex), a perennial, hummock-forming grass, widely found throughout much of arid and semi-arid Australia. The species possesses several attributes which make it suitable for biogeochemical exploration, being ubiquitous in the area, readily harvested and capable of the uptake of trace elements useful in geochemistry. Systematic sampling has been undertaken at 50 m intervals on widely spaced lines over several prospect areas. Collection of large samples from several plants at each sample station is desirable to try to obtain a representative sample. Initial multi-element analytical work utilizing small samples ( c . 2.5 g) of dried and shredded vegetation did not allow sufficient resolution of anomalies, with most results for Au and Pt being below detection levels. However, preconcentration by ashing of substantially larger samples ( c . 30 g) has allowed anomaly thresholds for those elements to be more readily defined. The species displays extensive geochemical variability for precious metals, pathfinders, base metals and major cations suggesting it offers much promise as a sampling medium. Test sampling traverses across known gold occurrences confirm the effectiveness of the technique in areas of thick cover sequences.

The response in elemental concentrations and Pb isotopes in various surface media from the Cigar West unconformity-type uranium deposit located at a depth of 450m were measured to ascertain if element migration from the deposit can be detected at the surface. The media included clay-size fractions separated from the A2, B and C soil horizons, and tree cores and twigs from black spruce (Picea mariana) and jack pine (Pinus banksiana) trees. Lead isotopes were used to trace any effect on the surface media from the deposit at depth because the 207Pb/206Pb ratios in the ore are<0.1, whereas the background values in the basin are>0.7 and modern anthropogenic Pb from aerosols are near 0.9. The tree cores record their lowest and therefore most radiogenic 207Pb/206Pb ratios of<0.7 near the surface projection of the deposit and associated structures, particularly in tree rings that predate any exploration and drilling activity in the area. The median 207Pb/206Pb ratios increase in the order C, B soil horizon clays, tree cores, A2 soil clays and twigs because of the increasing contribution of common Pb with high ratios from anthropogenic sources that affect the shallowest media the most. Although this anthropogenic Pb as well as that from the background dominates the composition of all media at the surface and the contribution from the deposit at depth is diminished toward the surface, ore-related Pb is still present as a few percent of the composition of pathfinder elements and Pb isotopes.

Interactions of macrofungi with U, Th, Pb and Ag were investigated in the former ore mining district of Příbram, Czech Republic. Samples of saprotrophic (34 samples, 24 species) and ectomycorrhizal (38 samples, 26 species) macrofungi were collected from a U-polluted Norway spruce plantation and tailings and analyzed for metal content. In contrast to Ag, which was highly accumulated in fruit-bodies, concentrations of U generally did not exceed 3mg/kg which indicates a very low uptake rate and efficient exclusion of U from macrofungi. In ectomycorrhizal tips (mostly determined to species level by DNA sequencing), U contents were practically identical with those of the non-mycorrhizal fine spruce roots. These findings suggest a very limited role of macrofungi in uptake and biotransformation of U in polluted forest soils. Furthermore, accumulation of U, Th, Pb and Ag in macrofungal fruit-bodies apparently does not depend on total content and chemical fractionation of these metals in soils (tested by the BCR sequential extraction in this study).

Biogeochemical samples were collected from the Norra Karr Alkaline Complex, a rare earth element (REE) and zirconium enriched deposit in Southern Sweden, to determine which sample medium is the most effective grassroots exploration tool for delineating concealed REE mineralization. The fern species Diyopteris filix-mas and Athyrium filix-femina were found to be widespread in the study area and surrounding countryside, and particularly efficient at concentrating high levels of REEs in their leaf tissue.There was distinct elemental fractionation in all three fern species. Each species showed enrichment in the LREEs (light rare earth elements), especially A. filix-femina. D. filix-mas showed the most enrichment in HREEs (heavy rare earth elements); Pteridium aquilinum had lower levels of REEs than the other two species.The best contrast was observed in D. filix-mas samples from areas over mineralization compared to samples taken over barren Vaxjii granites, which suggests that D. filix-mas is the preferred biogeochemical sample medium for REE exploration in this environment. (C) 2012 Elsevier B.V. All rights reserved.

Concentrations of uranium, thorium and rare earth elements (REE) in 36 species of ectomycorrhizal (26 samples) and saprobic (25 samples) macrofungi from unpolluted sites with differing bedrock geochemistry were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Analytical results are supported by use of certified reference materials (BCR-670, BCR-667, NIST-1575a) and the reliability of the determination of uranium was verified by epithermal neutron activation analysis (ENAA). It appears that data recently published on these elements are erroneous, in part because of use of an inappropriate analytical method; and in part because of apparent contamination by soil particles resulting in elevated levels of thorium and REE. Macrofungi from unpolluted areas, in general, did not accumulate high levels of the investigated metals. Concentrations of uranium and thorium were generally below 30 and 125 μg kg−1 (dry weight), respectively. Concentrations of REE in macrofungi did not exceed 360 μg kg−1 (dry weight) and their distribution more or less followed the trend observed in post-Archean shales and loess.

Macrofungi are effective accumulators of Ag. This study provides a comprehensive review of this phenomenon supported by original data on the Ag concentrations of macrofungi from pristine and Ag-polluted areas. In pristine areas, the median Ag concentrations of ectomycorrhizal (ECM) and saprobic (SAP) macrofungi were 0.79 and 2.94 mg kg− 1, respectively. In these areas, hyperaccumulation thresholds for Ag in ECM and SAP macrofungi are proposed as 100 and 300 mg kg− 1, respectively. In a Ag-polluted area, the Ag concentrations in macrofungi (ECM and SAP) were significantly elevated with the median value of 24.7 mg kg− 1 and the highest concentrations in Amanita spp. of the section Vaginatae (304–692 mg kg− 1). The intracellular speciation of Ag in fruit-bodies of the Ag-accumulator Amanita submembranacea was inspected by size exclusion chromatography followed by sulfhydryl-specific fluorimetric assays of ligands using reverse phase high-performance liquid chromatography and improved polyacrylamide gel electrophoresis. Virtually all Ag was found to be intracellular and sequestered in the major 7 kDa and minor 3.3 kDa complexes. The lack of glutathione and phytochelatins and the presence of a single 3 kDa sulfhydryl-containing peptide in the isolated Ag-complexes suggest that detoxification of Ag in A. submembranacea may rely on metallothionein. Vertical distribution of Ag in a polluted forest soil profile has shown substantial enrichment in organic horizons; in polluted technosol, the highest Ag concentrations were found in surface layers. Standardized EDTA extraction of Ag in both the investigated soil profiles showed relatively low Ag extractibility, generally within the range of 2.2–7.7% of total Ag content.

Samples of macrofungi collected in the vicinity of the Mokrsko gold deposit were analyzed for Au by INAA and ICP-MS. Ectomycorrhizal fungi yielded from 0.88 to 564 mu g kg(-1) Au (dry weight) in 79 samples. Saprobic fungi (75 samples) from the same locations yielded significantly higher concentrations: 3-7739 mu g kg(-1) Au (dry weight), with the highest contents in Lycoperdon perlatum. These are the highest recorded concentrations of Au in naturally-occurring fungi/vascular plants. Concentrations of Au in ectomycorrhizae were approximately 4-10 times higher than those in fine roots. It appears that saprobic fungi, namely several terrestrial saprobes of the genera Agaricus and Lycoperdon, are more efficient than ectomycorrhizal fungi at taking up Au, probably assisted by other microbiota and/or by a range of naturally-occurring compounds that have yet to be identified. The present data demonstrate that macrofungi are involved in the biogeochemical cycling of Au. (C) 2009 Elsevier Ltd. All rights reserved.

Two ectomycorrhizal macrofungal Amanita species of the section Lepidella, A. strobiliformis and A. solitaria, were found to hyperaccumulate silver (Ag). All samples were collected from non-argentiferous areas with background Ag content in soils (0.07–1.01mgkg−1 Ag). The Ag contents of both Amanita species were mostly in the range of 200–700mgkg−1 d.w. with the highest Ag content of 1253mgkg−1 in one sample of A. strobiliformis. Silver concentrations in macrofungal fruit bodies were commonly 800–2500 times higher than in underlying soils. A. strobiliformis and A. solitaria are the first eukaryotic organisms known to hyperaccumulate Ag.

On hearing of this new book, I was intrigued to see what the approach would be in comparison to the classic compendium with the similar title Trace Elements in Soils and Plants (Kabata-Pendias & Pendias 19XX). The approach in this new book is, indeed, very different and considerably more restricted in scope, covering only a few elements. Irina Shtangeeva has assembled a miscellany of articles written by 17 professionals from ten countries, but the only seven elements that are discussed in any detail are As, Au, Cd, Cu, Pb, Sc and Th, plus a chapter on rare earth elements (REE). The prospective purchaser should be aware, therefore, that the intention of this book is not to provide a comprehensive overview of a wide range of elements, but to focus on specific topics using these few elements as examples. Furthermore, there is a strong focus in most chapters on procedures relevant to the environmental sciences rather than exploration geochemistry. The topic of the first chapter, ‘Multi-element analysis of plant and soil samples’ by S. Ayrault, is large in scope and therefore challenging to summarize in just a paragraph. The author very briefly outlines procedures involved in sampling, sample preparation, analysis by non-destructive techniques (INAA, Synchrotron XRF, and proton-induced X-ray emission [PIXE]) and by destructive methods (AAS, ICP-AES and ICP-MS). As the writer declares ‘the aim [is] to give a clear idea of their potential use in environmental studies’. There are lists of some common reference materials (SRMs) and some brief comments on quality control. Useful tables are provided that compare the pros and cons of ICP-MS and INAA, and a summary is given on the recommended analytical method for selected elements. However, only 48 elements are listed, with Ag …

Ef fec tive min eral ex plo ra tion in the Nechako Pla teau and ad join ing re gions of cen tral Brit ish Co lum bia has for many years been hin dered by thick for est cover, an ex ten sive blan ket of till and other gla cial de pos its and, lo cally, wide spread Ter tiary ba salt cover. Where un der taken, re gional till and lake sed i ment geo chem i cal sur veys have been ef fec tive as re con nais sance ex plo ra tion tech niques. How ever, few pub licly avail able stud ies have been con ducted here into the use of surficial geo chem is try to aid in prioritizing re gional geo chem i cal anom a lies, or in car ry ing out the most ef fec tive geo chem i cal sur veys at a prop erty scale in ar eas of ex otic cover. In this re spect, BC has lagged far be hind other pro vin cial and in ter na tional ju ris dic tions in un der tak ing ap plied geo chem i cal ex plo ra tion re search.

⇓Fig. 113 February 2001 Fig. 1. On 23 January the world lost another legendary figure in geochemistry. Born in Bristol to an English father and French mother, Robert Brooks spent the first 30 years of his life in England. During that period he served in the British army in the Middle East and East Africa, then attended Bristol University from which he received his BSc (Hons) in Chemistry in 1952. After working for a while as an analytical chemist, he moved to South Africa in 1956 and, under the tutorship of Louis Ahrens, received a PhD in Geochemistry from the University of Cape Town in 1960. That same year he took an academic staff position in New Zealand at Massey University in Palmerston North, where he remained based for the rest of his life. During his 40 years at Massey University, he travelled widely and developed an increasingly broad range of interests and expertise on a wide range of subjects. Among his distinctions, Professor …

The surface geochemical response to bedrock containing elevated levels of the platinum group elements (PGE) is commonly so subtle that standard geochemical methods are insufficiently sensitive to assist the exploration geologist. At the Geological Survey of Canada, recent research on analytical methods by one of us (GEMH) has been directed toward the development of a selective leach of soils and sediments that will provide improved methodology for the detection of precious metals.

Biogeochemical methods have been widely used for mineral exploration, particularly in boreal forests and semi-arid regions, but there have been fewer applications in tropical areas. This paper describes a biogeochemical method of exploration for Au in equatorial regions. After investigation of several plant species, Astronidium palauense, a small- to moderate-size tree, was found to have many suitable attributes. (1) It is widely distributed in the southwest Pacific, although its occurrence may be limited at elevations greater than 1000 m. (2) The tree is easy to identify and is sufficiently common (e.g., one tree per 100 m2 on Simberi and Lihir Islands, Papua New Guinea) for detailed sampling. (3) The outer bark is easy to obtain and the ashed bark reliably indicates Au concentrations in the substrate. (4) The root system reaches at least 4 m depth, allowing greater penetration than surface soil samples, which is important in volcanic terrains where geochemical targets may be buried by post-mineralization volcanic eruption or debris flows. (5) The areal distribution of the root system samples a large volume of soil (ca. 100 m3), which reduces the nugget effect for Au. (6) The ease of sampling and low weight of bark reduces the time and cost over soil surveys, for example 6 minutes per site compared with 15 minutes per 1 m deep soil. Bark can be ashed in the field, 200–500 samples in 2 to 4 days, then shipped for multi-element (Au, As + 32 elements) instrumental neutron activation analysis (INAA). Field tests on Simberi and Lihir Islands, PNG, show that biogeochemical surveys have a high level of reliability for identification of prospects.