Lode and placer gold composition in the Klondike District, Yukon Territory, Canada; implications for the nature and genesis of Klondike placer and lode gold deposits

Knight, J.; Mortensen, J. K.; Morison, S R

doi:10.2113/gsecongeo.94.5.649

Cited by 77 publications

(43 citation statements)

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“…This geographical correlation implies that gold in the Klondyke valleys is generally close to source. Knight et al (7) reported that the vein mineralogy of lodes throughout the region is dominated by base metal sulphides and arsenopyrite and during this study inclusions of galena, pyrite, chalcopyrite and arsenopyrite were observed in alluvial gold with silver contents of over 20% which suggests that this type of gold is derived from a number of related sources of mineralization. An inclusion of hessite ((Ag,Au)2Te) was recorded in the population of low-silver (15% Ag) gold from Bonanza Creek which raises the possibility of an additional unrecorded bedrock source to that from the Lone Star lode.…”

Section: Platesupporting

confidence: 58%

“…Knight et al (7,26) undertook an extensive study of the chemical composition of both alluvial and lode gold from the Klondike district in an attempt to clarify the discrepancy between the amount of alluvial gold won from the region with the potential of known lode gold occurrences. They determined the chemical composition of the cores of 2,700 gold grains in terms of silver, mercury and copper content and were able to characterize the populations of alluvial gold in the various valleys according to the characteristics of different types of known lode gold.…”

Section: Figurementioning

confidence: 99%

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Microchemical Characterization of Alluvial Gold Grains as an Exploration Tool

2002

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There is considerable variation in the composition of native gold and the nature of minerals co-existing with it, and this reflects differences in the geological environment and chemistry of ore-forming processes. In areas where gold-bearing mineralization is subject to active fluvial erosion, especially in temperate climatic regimes, any discrete grains of native gold pass into alluvial sediment with little modification. The chemical characteristics of alluvial grains and the nature of preserved mineral inclusions provide a signature which points back to the type of source mineralization. This signature may be established using electron probe microanalysis and scanning electron microscopy and can be interpreted to provide information about the original bedrock mineralization. Identification of the type of source mineralization using the technique at an early stage in regional exploration can help focus attention on targets with the most potential economic importance.

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Section: Platesupporting

confidence: 58%

Section: Figurementioning

confidence: 99%

Microchemical Characterization of Alluvial Gold Grains as an Exploration Tool

2002

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“…Natural gold may be characterized according to the other elements present in the alloy (e.g., Knight et al 1999) and the suite of mineral inclusions which are revealed in polished sections, (e.g., Chapman et al 2000). Morrison et al (1991) identified some broad differences in the compositional range of gold from different styles of mineralization; for example, epithermal mineralization may yield gold with a wide range of Au/Ag ratios, and gold from porphyry environments typically exhibits a slightly higher Cu content.…”

Section: Introductionmentioning

confidence: 99%

A new indicator mineral methodology based on a generic Bi-Pb-Te-S mineral inclusion signature in detrital gold from porphyry and low/intermediate sulfidation epithermal environments in Yukon Territory, Canada

et al. 2017

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Porphyry-epithermal and orogenic gold are two of the most important styles of gold-bearing mineralization within orogenic belts. Populations of detrital gold resulting from bulk erosion of such regions may exhibit a compositional continuum wherein Ag, Cu, and Hg in the gold alloy may vary across the full range exhibited by natural gold. This paper describes a new methodology whereby orogenic and porphyry-epithermal gold may be distinguished according to the mineralogy of microscopic inclusions observed within detrital gold particles. A total of 1459 gold grains from hypogene, eluvial, and placer environments around calcalkaline porphyry deposits in Yukon (Nucleus-Revenue, Casino, Sonora Gulch, and Cyprus-Klaza) have been characterized in terms of their alloy compositions (Au, Ag, Cu, and Hg) and their inclusion mineralogy. Despite differences in the evolution of the different magmatic hydrothermal systems, the gold exhibits a clear Bi-Pb-Te-S mineralogy in the inclusion suite, a signature which is either extremely weak or (most commonly) absent in both Yukon orogenic gold and gold from orogenic settings worldwide. Generic systematic compositional changes in ore mineralogy previously identified across the porphyry-epithermal transition have been identified in the corresponding inclusion suites observed in samples from Yukon. However, the Bi-Te association repeatedly observed in gold from the porphyry mineralization persists into the epithermal environment. Ranges of P-T-X conditions are replicated in the geological environments which define generic styles of mineralization. These parameters influence both gold alloy composition and ore mineralogy, of which inclusion suites are a manifestation. Consequently, we propose that this methodology approach can underpin a widely applicable indicator methodology based on detrital gold.

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“…There are many examples of placer gold occurrences for which the source mineralization has not been identified (e.g., the Klondike District placers, Yukon Territory, Canada (e.g., Knight et al, 1999a); Ninemile Valley, central Western Montana, USA (Lange and Gignoux, 1999)). Several workers have applied the chemical characteristics of the placer gold to aid the exploration process.…”

Section: Introductionmentioning

confidence: 99%

“…According to the nature of the placer gold studied the various elements of the microchemical signature assume different importance. Thus alloy composition alone is capable of discriminating between placer gold from multiple sources in the Klondike District (Knight et al, 1999a) but the study of mineral inclusions has proved to be more revealing in some cases; for example, in detecting subtle differences between metasediment hosted gold on a local and regional scale in Great Britain and Ireland (Chapman et al, 2000a,b). The most useful data derives from correlating different opaque inclusion assemblages with variations in alloy composition to identify multiple populations of gold represented in a single placer.…”

Section: Introductionmentioning

confidence: 99%