Automated Gold Grain Counting. Part 2: What a Gold Grain Size and Shape Can Tell!
| Autor: | Jonathan Tremblay, Sheida Makvandi, Hugues Longuépée, Alexandre Néron, Réjean Girard |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
lcsh:QE351-399.2
Scanning electron microscope gold grain size Sorting (sediment) Mineralogy 010501 environmental sciences Elutriation 010502 geochemistry & geophysics 01 natural sciences glacial sediments 0105 earth and related environmental sciences automated SEM lcsh:Mineralogy Sediment food and beverages Geology gold Geotechnical Engineering and Engineering Geology Grain size gold exploration drift prospecting Particle-size distribution till Sediment transport gold grain morphology Shape analysis (digital geometry) |
| Zdroj: | Minerals, Vol 11, Iss 379, p 379 (2021) Minerals Volume 11 Issue 4 |
| Popis: | Glacial drift exploration methods are well established and widely used by mineral industry exploring for blind deposit in northern territories, and rely on the dispersion of mineral or chemical signal in sediments derived from an eroded mineralized source. Gold grains themselves are the prime indicator minerals to be used for the detection of blind gold deposits. Surprisingly, very little attention has been dedicated to the information that size and shape of gold grain can provide, other than a simple shape classification based on modification affecting the grains that are induced in the course of sediment transport. With the advent of automated scanning electron microscope (SEM)-based gold grain detection, high magnification backscattered electron images of each grain are routinely acquired, which can be used for accurate size measurement and shape analysis. A library with 88,613 gold grain images has been accumulated from various glacial sediment surveys on the Canadian Shield and used to detect trends in grains size and shape. A series of conclusions are drawn: (1) grain size distribution is consistent among various surveys and areas, (2) there is no measurable fine-grained gold loss due to natural elutriation in ablation or reworked till, or during the course of reverse circulation drilling, (3) there is no grain size sorting during glacial transport, severing small grains from large ones, (4) shape modification induced by transport is highly dependent on grain size and original shapes, and (5) the use of grain shape inherited from neighboring minerals in the source rocks is a useful feature when assessing deposit types and developing exploration strategies. |
| Databáze: | OpenAIRE |
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