Effective mineral exploration for gold using geology, Quaternary geology and exploration geochemistry in areas of shallow till

Gleeson, C F; Rampton, V N; Thomas, R D; Paradis, Suzanne

doi:10.4095/127365

Cited by 6 publications

(3 citation statements)

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“…Consequently, element concentrations in B-horizon soils can be highly variable even though they are relatively uniform in the underlying bedrock. In contrast, samples collected from within the C-horizon are comparatively unaffected by the pedogenic processes operative in the A-and B-soil horizons (Agriculture Canada Expert Committee on Soil Survey 1987; Gleeson et al 1989) and element concentrations commonly reflect mechanical rather than hydromorphic dispersal processes. The utility of sampling C-horizon soil developed on basal tills for outlining areas of mineralization has long been known (e.g.…”

Section: Evaluating Soil Geochemical Anomaliesmentioning

confidence: 99%

Regional till geochemical surveys in the Canadian Cordillera: sample media, methods and anomaly evaluation

Levson

2001

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Basal tills have become a widely used regional geochemical sampling medium in recent years in the Canadian Cordillera. They reflect the primary composition of the source bedrock and contrast with B-horizon soil that can be developed on a variety of glacial and non-glacial surficial sediment types. Detailed sedimentological data are critical to collect and they are used to differentiate basal tills from other visually similar sediments including englacial and supraglacial tills, colluvial debris flow deposits, and very poorly sorted, glaciofluvial or glaciolacustrine sediments (e.g. diamictons or gravelly muds). The variable transport and depositional processes that form these different sediments make interpretation of geochemical data difficult. Deep (usually > 0.75m) C-horizon sampling of basal till minimizes the complicating effects of pedogenesis, weathering, surface washing and gravity remobilization of the tills. The latter processes, particularly pronounced in the wet, steep terrain, typical of much of the Canadian Cordillera, lead to depleted concentrations of heavy minerals (notably Au) and hydromorphic dispersion of mobile elements in the near surface sediments. Also, elements that are preferentially concentrated in the fine fraction can be selectively removed by surface waters.Offset sampling lines, oriented perpendicular to the dominant ice-flow direction, are most effective for detecting regional geochemical anomalies which are typically narrow and elongated parallel to ice-flow. Erratics trains and till anomalies are usually a few to several kilometres long and up to one or more kilometres wide. For some metals such as Au, anomalies are generally larger and more readily detected in till than in B-horizon soil. Surface till anomalies reflect up-ice sources and not the immediately underlying bedrock; down-ice displacements of > 500 m often occur in areas of thick till. Basal till anomalies usually can be traced to source along linear transport paths reflecting topographically controlled valley-glacier flow in mountainous areas and unidirectional ice-sheet flow in many plateau areas, chiefly representative of the last glacial event. Interpretations of till geochemical data are enhanced with a clear understanding of the surficial and bedrock geology, Quaternary stratigraphy, ice-flow history and down-ice dispersal characteristics around known mineral deposits.

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Section: Evaluating Soil Geochemical Anomaliesmentioning

confidence: 99%

Regional till geochemical surveys in the Canadian Cordillera: sample media, methods and anomaly evaluation

Levson

2001

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“…Different sampling densities, fractions and soil horizons have been used in Au exploration e.g. by Shilts (1984), Bloom and Steel (1989), Gleeson et al (1989), McClenaghan (1992), Nichol et al (1992), Hartikainen and Nurmi (1993), and Sibbick and Fletcher (1993). The importance of knowledge on glacial history and till stratigraphy in prospecting has been stressed by Campbell and Schreiner (1989), Hirvas (1989), Hirvas and Nenonen (1990), Aario and Peuraniemi (1992), and McClenaghan et al (1992).…”

Section: Introductionmentioning

confidence: 99%

Glacial geology and till geochemistry in ore exploration in the Tervola area, southern Finnish Lapland

Sarala¹,

Peuraniemi²,

Aario³

1998

Bull Geol Soc Finland

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“…Till geochemical surveys have long been used as a conventional mineral exploration method in glaciated terrains globally and there are numerous examples of successful studies (e.g. Peuraniemi 1982, Gleeson et al 1989Hirvas & Nenonen 1990;Aario & Peuraniemi 1992;Nichol et al 1992;McClenaghan et al 2000). The key to interpretation of till geochemical results is to recognise the glaciogenic processes that have affected the till.…”

mentioning

confidence: 97%

Gold exploration using heavy minerals in till and weathered bedrock in Petäjäselkä, northern Finland

Taivalkoski

Sarala

Hulkki

2015

GEEA

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As a part of a gold exploration project in Petäjäselkä, northern Finland, carried out by the Geological Survey of Finland, heavy mineral studies and detailed till geochemical and stratigraphical studies were used for mineral exploration. These studies covered c. 22 km 2 in the Petäjäselkä area. The objective of this research was to find out how heavy minerals and till geochemistry can be used in gold exploration, and how they reflect the glacial dispersion in shallow till areas in Petäjäselkä. Furthermore, an automated mineralogical identification method (SEM-EDS) was tested in the indicator mineral research.Samples from till and underlying, pre-glacially weathered bedrock were collected from the test pits and trenches. A total of 381 heavy mineral and 713 geochemical samples were collected. The heavy mineral samples were concentrated with a spiral concentrator and a Knelson concentrator. The geochemical samples were analysed by ICP-AES and GF-AAS following aqua regia decomposition. The elevated gold contents and distinct anomalies found in till and weathered bedrock indicate the whole study area to have potential for gold mineralization. Based on microscopic and automated mineralogical studies, native gold was the only useful indicator mineral present in the heavy mineral samples for gold exploration in Petäjäselkä. The detailed till geochemical results show that the glacial transport distance in Petäjäselkä is short, only some tens of meters. Differences in the Au-Ag contents of the gold grains were noted between the three gold mineralized targets in Kerolaki, Selkä-Mäntypää and Ranta-Mäntypää. Arsenic, bismuth and tellurium proved to be pathfinder elements for gold mineralization both in till and weathered bedrock. The results of this study show that the heavy mineral studies, together with till geochemical studies, provide a useful method for identifying exploration targets in glaciated terrain. However, different methods of heavy mineral concentration affect the recovery of gold grains and thereby the final results of this study.

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Effective mineral exploration for gold using geology, Quaternary geology and exploration geochemistry in areas of shallow till

Cited by 6 publications

References 0 publications

Regional till geochemical surveys in the Canadian Cordillera: sample media, methods and anomaly evaluation

Regional till geochemical surveys in the Canadian Cordillera: sample media, methods and anomaly evaluation

Glacial geology and till geochemistry in ore exploration in the Tervola area, southern Finnish Lapland

Gold exploration using heavy minerals in till and weathered bedrock in Petäjäselkä, northern Finland

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