Electron microprobe analyses of native silver and associated arsenides from the Great Bear Lake silver deposits, Northwest Territories, Canada

1986 ◽  
Vol 23 (10) ◽  
pp. 1470-1479 ◽  
Author(s):  
A. Changkakoti ◽  
R. D. Morton
Keyword(s):  
Northwest Territories ◽  
Electron Microprobe ◽  
Hydrothermal Fluids ◽  
Bear Lake ◽  
Wide Range ◽  
Silver Deposits ◽  
Native Silver ◽  
Host Rocks

The Great Bear Lake silver deposits in the Northwest Territories of Canada occur within two separate domains, namely the Echo Bay sector and the Camsell River sector. In these deposits, native silver occurs in veins, associated with a wide range of Ni-, Co-, and Fe-arsenides, sulphides, and pitchblende in gangues of quartz, calcite, dolomite, rhodochrosite, and fluorite. The host rocks of the veins are for the most part Aphebian volcano-sedimentary roof pendants within the Great Bear batholithic complex. Native silver, nickeline (niccolite), maucherite, safflorite, rammelsbergite, pararammelsbergite, loellingite, skutterudite, cobaltite, gersdorffite, and arsenopyrite were analyzed on the electron microprobe to determine any local or regional chemical variations. Mercury and antimony were found to occur in significant quantities in the majority of the native-silver samples. The silver samples from the Camsell River sector were found to be generally more enriched in mercury than those of the Echo Bay sector. Nickeline, cobaltite, and gersdorffite were found to be enriched in arsenic in the ores of the Camsell River sector, versus those of the Echo Bay sector. Such variations are probably related to differing magmatic sources for the hydrothermal fluids or even to precursor metallo-organic associations and are not due to different rocks hosting the silver-bearing veins.

Oxygen, hydrogen, and carbon isotopic studies of the Great Bear Lake silver deposits, Northwest Territories

1986 ◽  
Vol 23 (10) ◽  
pp. 1463-1469 ◽  
Author(s):  
A. Changkakoti ◽  
R. D. Morton ◽  
J. Gray ◽  
C. J. Yonge
Keyword(s):  
Meteoric Water ◽  
Carbon Isotopic ◽  
Bear Lake ◽  
Lake Region ◽  
Wide Range ◽  
Silver Deposits ◽  
Isotopic Studies ◽  
Native Silver ◽  
Host Rocks ◽  
Late Stages

The native-silver-bearing deposits of the Great Bear Lake region occur within two separate domains, namely the Echo Bay sector and the Camsell River sector. In all these deposits, native silver occurs in veins, associated with a wide range of Ni-, Co-, and Fe- arsenides, Cu-, Fe-, Ni-, and Co-sulfides, and pitchblende in gangues of quartz, calcite, dolomite, siderite, rhodochrosite, and fluorite. The host rocks of the veins are for the most part Aphebian volcano-sedimentary roof pendants within the Great Bear batholithic complex. The carbonates (calcite, dolomite, siderite, and rhodochrosite) show a wide range of δ18O (6.8 to 22.5‰, SMOW) and δ13C (−2.7 to −13.3‰, PDB) values. A single analysis of quartz gave a δ18O value of 16.54‰ (SMOW). The δD of water in fluid inclusions in quartz, dolomite, and calcite shows a range from −62.2 to −98.5‰ (SMOW). The δD of present-day meteoric waters from the region shows a range of −146.5 to −165.2‰ (SMOW). The δ18O of the hydrothermal fluids (0.47 to 9.12‰, SMOW) was calculated from the δ18O values of the quartz, calcite, and dolomite belonging to different paragenetic sequences. The δ13C of carbon (−2.8 to −8.6‰, PDB) in the hydrothermal fluid was calculated from the δ13C values of the calcites. The oxygen, carbon, and hydrogen isotopic values indicate that in the early stages of mineralization, magmatic water and carbon from a magmatic source were predominant. During the late stages of mineralization, the influence of meteoric water became more pronounced.

Compositional variation in the chevkinite group: new data from igneous and metamorphic rocks

2009 ◽  
Vol 73 (5) ◽  
pp. 777-796 ◽  
Author(s):  
R. Macdonald ◽  
H. E. Belkin ◽  
F. Wall ◽  
B. Baginski
Keyword(s):  
Electron Microprobe ◽  
Host Rock ◽  
Metamorphic Rocks ◽  
Compositional Variation ◽  
Temperature Range ◽  
Wide Range ◽  
Host Rocks ◽  
Cation Sites ◽  
Dominant Cation

AbstractElectron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most MgO-rich phases yet recorded, and we report two further examples where La is the dominant cation in the A site. Patchily- zoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions. The new and published analyses are used to review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host rock compositions and over a substantial pressure- temperature range. The dominant substitutions in the various cation sites and a generalized substitution scheme are described.

Chapter 4: Hemlo Gold System, Superior Province, Canada

2020 ◽  
pp. 81-100
Author(s):  
K. Howard Poulsen ◽  
Rodney Barber ◽  
François Robert
Keyword(s):  
Gold Deposits ◽  
Hydrothermal Fluids ◽  
Superior Province ◽  
Exact Nature ◽  
Silicate Mineral ◽  
Clastic Rocks ◽  
Wide Range ◽  
Alteration Minerals ◽  
Felsic Volcanic ◽  
Host Rocks

Abstract Hemlo combines several rare to unique features in the spectrum of Archean greenstone gold deposits. It is an isolated, approximately 800-metric ton (t) gold system in a region of otherwise limited known gold endowment. The geology of Hemlo is dominated by deformed and metamorphosed sedimentary, felsic volcanic, and volcaniclastic units, a premineral coherent felsic porphyry, and a swarm of mainly postmineral, intermediate, feldspar-phyric dikes. Ore is dominantly in the form of gold-bearing lenses of pyritic, feldspathic schist derived from deformation of both the clastic rocks and the felsic porphyry. The deposit and its host rocks were metamorphosed at moderate pressures to assemblages diagnostic of the mid-amphibolite facies, followed by progressive retrogression to those of the greenschist facies. The result is a wide range of silicate mineral species in ambiguous textural relationships. The gold system itself is known for ore and related alteration minerals with significant concentrations of Mo-As-Sb-Hg-Tl-V-Ba-K-Na. The inferences derived from lithologic mapping, structural chronology, U-Pb geochronology, and mineral paragenesis favors an interpretation of Hemlo as a deformed and metamorphosed gold system formed from oxidized hydrothermal fluids in an upper crustal setting. Uncertainty remains as to the exact nature and geometry of that ore-forming hydrothermal system, however, and the role subsequent metamorphism and deformation have played in the local remobilization of ore constituents into their present paragenetically late structural sites.

Silver deposits associated with the Proterozoic rocks of the Thunder Bay District, Ontario

1986 ◽  
Vol 23 (10) ◽  
pp. 1576-1591 ◽  
Author(s):  
J. M. Franklin ◽  
S. A. Kissin ◽  
M. C. Smyk ◽  
S. D. Scott
Keyword(s):  
Lake Superior ◽  
Normal Faults ◽  
Western Margin ◽  
Metasedimentary Rocks ◽  
Mafic Intrusions ◽  
Thunder Bay ◽  
Silver Deposits ◽  
Base Metal Sulphides ◽  
Native Silver ◽  
Host Rocks

The silver deposits to the immediate north and west of Lake Superior are divided into three groups. The Mainland veins, the largest group, occur along a zone of normal faults near the western margin of the Proterozoic rocks of the Southern Province. The most economically productive deposits, the Island group, arc in or very near a northeast-trending swarm of gabbro dykes lying immediately offshore the northwestern shore of Lake Superior. The third group occurs near the western margin of the Port Coldwell alkalic complex; these veins are in a shear zone that cuts both Archean metasedimentary rocks and a Proterozoic diabase dyke. The Mainland deposits occur in the Rove shale, immediately below the contact with Logan diabase sills. The veins locally extend upwards into the sills, but the silver-bearing portions, consisting of acanthite and native silver associated with base-metal sulphides, fluorite, barite, quartz, and calcite, are largely bounded by locally silicified shale. The Island veins, typified by the Silver Islet mine, are in fractures perpendicular to the gabbro-dyke host rocks. These veins contain both native silver and acanthite, associated with a Ni–Co sulpharsenide suite and the same mineral assemblage as the Mainland deposits. The veins near Coldwell are rich in sphalerite and galena.Lead-isotope data indicate that the Mainland and Island veins are genetically related and that the Mainland veins formed from an inhomogeneous fluid. Two-stage calculations indicate an early Proterozoic source rock, possibly the Rove shale. The Island veins are more isotopically homogeneous, and their metals may have been derived partially from the gabbro. The Coldwell veins contain lead that is less radiogenic than that of the other two groups and is possibly derived from the adjacent Archean rocks. All three groups of deposits have isotopic compositions that are much less uranogenic and more thorogenic than the nearby Pb–Zn–Ba veins of the Dorion area. Preliminary fluid-inclusion data from the Mainland veins indicate that deposition occurred from a fluid whose temperature varied from approximately 200 °C to more than 400 °C; deposition occurred during boiling induced by adiabatic expansion of the fluid at relatively shallow crustal depths. The Mainland veins developed in the shale (rather than the diabase), as its high fissility, and hence permeability, made it susceptible to intense fracturing by the expanding fluid. Both the Mainland and Island groups were deposited in structures formed dominantly by listric normal faulting during late stages of intracontinental rifting. Heat was supplied by abundant mafic intrusions that formed coincident with rifting. The ore fluid was probably formed as a result of metamorphic dewatering, with metals released to the fluid because of silicate and sulphide recrystallization.

scholarly journals Clinical and Forensic Aspects of the Different Subtypes of Argyria

2021 ◽  
Vol 10 (10) ◽  
pp. 2086
Author(s):  
Luís Mota ◽  
Ricardo Jorge Dinis-Oliveira
Keyword(s):  
Systemic Absorption ◽  
Histopathological Analysis ◽  
Wide Range ◽  
Silver Deposits ◽  
Specific Tissue ◽  
Eye Lesions ◽  
Dark Blue ◽  
Typical Skin ◽  
Viable Treatment

Argyria encompasses the different cosmetic alterations that can develop if enough silver particles deposit in a specific tissue, typically in the skin, ranging from localized dark-blue macules to a generalized slate-gray/bluish tinge following systemic absorption. This work aims to fully review the state of the art regarding pathophysiology, diagnosis, treatment, and relevant clinical and forensic features of argyria. Argyria has been diagnosed in a wide range of ages, both sexes and varied ethnicities, with no known individual predisposing factors. Ultraviolet radiation with subsequence increases of melanin production aggravates the discoloration due to a reduction in the silver deposits. Physical examination and silver exposure in the anamnesis can be highly suggestive of the diagnosis, but a histopathological analysis with Energy-Dispersive X-ray Spectroscopy is required to unequivocally determine the discoloration etiology. Safe and effective treatment has only been accomplished with laser techniques, though only a few cases have been reported and with limited follow-up time. In conclusion, argyria typically has an occupational or iatrogenic etiology. It should be suspected when a patient presents with typical skin or eye lesions. A seemingly viable treatment modality, with laser technology, is finally within the horizon.

scholarly journals Geology of the orogenic Cheminis gold deposit along the Larder Lake – Cadillac deformation zone, Ontario

2015 ◽  
Vol 52 (12) ◽  
pp. 1093-1108 ◽  
Author(s):  
Bruno Lafrance
Keyword(s):  
Deformation Zone ◽  
Volcanic Rocks ◽  
Tholeiitic Basalt ◽  
Hydrothermal Fluids ◽  
South Side ◽  
Shear Sense ◽  
Abitibi Subprovince ◽  
Deformation Features ◽  
Shear Sense Indicators ◽  
Host Rocks

The Larder Lake – Cadillac deformation zone (LLCDZ) is one of two major, auriferous, deformation zones in the southern Abitibi subprovince of the Archean Superior Province. It hosts the Cheminis and the giant Kerr Addison – Chesterville deposits within a strongly deformed band of Fe-rich tholeiitic basalt and komatiite of the Larder Lake Group (ca. 2705 Ma). The latter is bounded on both sides by younger, less deformed, Timiskaming turbidites (2674–2670 Ma). The earliest deformation features are F1 folds affecting the Timiskaming rocks, which formed either during D1 extensional faulting or during early D2 north–south shortening related to the opening and closure, respectively, of the Timiskaming basin. Continued shortening during D2 imbricated the older volcanic rocks and turbidites and produced regional F2 folds with an axial planar S2 cleavage. D2 deformation was partitioned into the weaker band of volcanic rocks, producing the strong S2 foliation, L2 stretching lineation, and south-side-up shear sense indicators, which characterize the LLCDZ. Gold is present in quartz–carbonate veins in deformed fuchsitic komatiites (carbonate ore) and turbiditic sandstone (sandstone-hosted ore), and in association with disseminated pyrite in altered Fe-rich tholeiitic basalts (flow ore). All host rocks underwent strong mass gains in CO2, S, K2O, Ba, As, and W, during sericitization, carbonatization, and sulphidation of the host rocks, suggesting that they interacted with the same hydrothermal fluids. Textural relationships between alteration minerals and S2 cleavage indicate that mineralization is syn-cleavage. Thus, gold was deposited as hydrothermal fluids migrated upward along the LLCDZ during contractional, D2 south-side-up shearing. The gold zones were subsequently modified during D3 reactivation of the LLCDZ as a dextral transcurrent fault zone.

Pseudoditrichum mirabile gen. et sp. nov. (Musci: Pseudoditrichaceae fam. nov.), a unique moss from Great Bear Lake, Northwest Territories

1974 ◽  
Vol 52 (4) ◽  
pp. 701-705 ◽  
Author(s):  
William Campbell Steere ◽  
Zennoske Iwatsuki
Keyword(s):  
Northwest Territories ◽  
New Genus ◽  
The Arctic ◽  
Phylogenetic Position ◽  
New Genus And Species ◽  
Arctic Circle ◽  
New Family ◽  
Bear Lake ◽  
Evolutionary Level

The name Pseudoditrichum mirabile Steere et Iwatsuki is proposed for a minute moss with leafy stem 1-3 mm high and seta 6 mm long; it was collected on calcareous silt near the Sloan River, Great Bear Lake, Northwest Territories, only a few miles south of the Arctic Circle. The gametophytic characters agree well with those of the Ditrichaceae, a relatively primitive family, but the peristome is clearly double, with the inner and outer teeth opposite, which thereby indicates a much more advanced phylogenetic position, perhaps at the evolutionary level of the Funariaceae. As the combination of gametophytic and sporophytic characteristics exhibited by this moss does not occur in any existing family of mosses, it is therefore deemed necessary to create the new family Pseudoditrichaceae for the new genus and species described here.

Variability in ice phenology on Great Bear Lake and Great Slave Lake, Northwest Territories, Canada, from SeaWinds/QuikSCAT: 2000–2006

2009 ◽  
Vol 113 (4) ◽  
pp. 816-834 ◽  
Author(s):  
Stephen E.L. Howell ◽  
Laura C. Brown ◽  
Kyung-Kuk Kang ◽  
Claude R. Duguay
Keyword(s):  
Northwest Territories ◽  
Bear Lake ◽  
Great Slave Lake ◽  
Ice Phenology
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