Review of till geochemistry and indicator mineral methods for mineral exploration in glaciated terrain

McClenaghan, M. B.; Paulen, R. C.; Smith, I. R.; Rice, J. M.; Plouffe, A.; McMartin, I.; Campbell, J. E.; Lehtonen, M.; Parsasadr, M.; Beckett-Brown, C. E.

doi:10.1144/geochem2023-013

Cited by 4 publications

(1 citation statement)

References 280 publications

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“…Till geochemistry is widely used for mineral exploration in glaciated terrain where till is widespread, has a relatively simple transport history, and a distinct composition that reflects its source material (e.g., [1][2][3][4][5][6][7][8]). Anomalous concentrations of ore and pathfinder elements in till can therefore be used to assess and trace back sources of potential mineralized bedrock.…”

Section: Introductionmentioning

confidence: 99%

Till Geochemistry as a Vector to Metasomatic Iron and Alkali-Calcic Systems and Associated Deposits in the Great Bear Magmatic Zone, Northwest Territories, Canada

Normandeau,

McMartin,

Corriveau

2024

Minerals

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Recent advances in the characterization of metasomatic iron and alkali-calcic (MIAC) systems with associated iron-oxide apatite (IOA) prospects and iron-oxide–copper–gold (IOCG) and metasomatic cobalt deposits of the Great Bear magmatic zone were used to determine if the geochemistry of glacial sediments can unveil pathfinder elements indicative of mineralization and associated alteration. Analysis of variance within bedrock lithogeochemical (n = 707 samples) and till geochemical datasets (n = 92 samples) are compared. Results show that Fe, Co, Ni, Cu, As, Mo, Bi, La, Th, U, and W were identified as potential vectoring elements in different fractions of till due to their anomalous concentrations down-ice of various mineralized outcrops within the study area. For instance, Fe, Co, Cu, and Mo were established as the most useful vectoring elements in the locally derived till (<2 km down-ice) near the Sue Dianne IOCG deposit, and Fe, Co, Ni, Cu, Mo, W, Bi, and U near the Fab IOCG prospect. At the Sue Dianne deposit, the ratios of near-total (4-acid digestion) versus partial (modified aqua regia digestion) concentrations in the silt + clay-sized till fraction (<0.063 mm) for both La and Th reflect the mineralization alteration signature and define a more consistent dispersal train from mineralization compared to element concentrations mapped alone. Additional testing in an area of continuous till cover near an isolated point source is recommended to further develop the elemental ratio method for exploration of MIAC systems.

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Section: Introductionmentioning

confidence: 99%

Till Geochemistry as a Vector to Metasomatic Iron and Alkali-Calcic Systems and Associated Deposits in the Great Bear Magmatic Zone, Northwest Territories, Canada

Normandeau,

McMartin,

Corriveau

2024

Minerals

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Gold in eskers and gyttja overlying auriferous till, Regnault deposit, Quebec

Cummings,

Orr,

MacDonald

2024

GEEA

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The Regnault gold deposit in Quebec, Canada, was discovered by Kenorland in 2020 following identification of a gold-in-till dispersal train. In 2022, two non-traditional media—eskers and organic lake-bottom mud (gyttja)—were sampled to determine if they likewise contained gold anomalies that vectored the mineral deposit. Striking, coherent (mappable) anomalies exist in both media. The gold-in-esker dispersal train has a similar pathfinder element association as the gold-in-till dispersal train (e.g., Te, W) but contains approximately twice the gold (average 73 ppb Au) in the <63 um fraction. It is hypothesized to be a meltwater-sorted version of the gold-in-till train, sourced from the erosional esker corridor some 3 km upflow. By contrast, the gold-in-gyttja dispersal train is substantially different than both the gold-in-esker and gold-in-till dispersal trains. It has lost significant association with pathfinder elements, contains an order of magnitude less gold (average 4.2 ppb Au), and is tentatively hypothesized to have a hydromorphic origin, sourced primarily from the gold-in-till dispersal train. The main takeaway from the study is that the sampling of any of these three media—eskers, gyttja or till—could have conceivably led to the discovery. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7235784

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Derivation of Predictive Layers Using Regional Till Geochemistry Data for Mineral Potential Mapping of the REE Line of Bergslagen, Central Sweden

Casey,

Morris,

Sadeghi

2024

Minerals

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With the increasing need for rare-earth elements (REEs) to reach the goals of the ongoing green energy transition, new and innovative methods are needed to identify new primary resources of these critical metals. This study explores the potential to use a non-biased, uniform till dataset to generate evidentiary layers that describe these critical factors and geochemical anomalies to aid mineral potential mapping (MPM) for REEs using machine-assisted methods. The till samples used in this study were collected from the “REE Line”, a sub-region within the Bergslagen lithotectonic province, Sweden, where numerous REE mineralizations occur. Multiple approaches were used in this study to isolate geochemical anomalies using multivariate methods, namely principal component analysis (PCA) and K-means clustering. Additional factors for classifying till samples were also tested, including alteration indices. Using known REE occurrences in Bergslagen as validation points, the results demonstrated the usefulness of multivariate methods applied to till geochemistry for predictive bedrock mapping, and to identify potential areas of REE mineralization within the REE line. The results of the alteration indices showed that the till geochemistry demonstrated similar levels of alteration when compared to the underlying bedrock, allowing for a regional alteration map to be generated. These results show that regional-scale till sampling can provide low-cost data for mineral exploration at the regional scale and generate usable evidentiary layers for GIS-based MPM.

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Review of till geochemistry and indicator mineral methods for mineral exploration in glaciated terrain

Cited by 4 publications

References 280 publications

Till Geochemistry as a Vector to Metasomatic Iron and Alkali-Calcic Systems and Associated Deposits in the Great Bear Magmatic Zone, Northwest Territories, Canada

Till Geochemistry as a Vector to Metasomatic Iron and Alkali-Calcic Systems and Associated Deposits in the Great Bear Magmatic Zone, Northwest Territories, Canada

Gold in eskers and gyttja overlying auriferous till, Regnault deposit, Quebec

Derivation of Predictive Layers Using Regional Till Geochemistry Data for Mineral Potential Mapping of the REE Line of Bergslagen, Central Sweden

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