The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada
The existing stratigraphic and structural subdivisions are refined, and temporal constraints indicate two prograde metamorphic events at Yellowknife. Four generations of structures are identified: (1) brittle syn-volcanic, (2) brittle-ductile, late first metamorphism, (3) brittle, post-first metamor...
Main Author: | |
---|---|
Format: | Text |
Language: | unknown |
Published: |
Scholarship@Western
1992
|
Subjects: | |
Online Access: | https://ir.lib.uwo.ca/digitizedtheses/2165 https://ir.lib.uwo.ca/context/digitizedtheses/article/3164/viewcontent/NN75342.PDF |
id |
ftunivwestonta:oai:ir.lib.uwo.ca:digitizedtheses-3164 |
---|---|
record_format |
openpolar |
spelling |
ftunivwestonta:oai:ir.lib.uwo.ca:digitizedtheses-3164 2023-10-01T03:58:24+02:00 The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada Webb, David R 1992-01-01T08:00:00Z application/pdf https://ir.lib.uwo.ca/digitizedtheses/2165 https://ir.lib.uwo.ca/context/digitizedtheses/article/3164/viewcontent/NN75342.PDF unknown Scholarship@Western https://ir.lib.uwo.ca/digitizedtheses/2165 https://ir.lib.uwo.ca/context/digitizedtheses/article/3164/viewcontent/NN75342.PDF Digitized Theses Geochemistry --Mineralogy text 1992 ftunivwestonta 2023-09-03T07:20:34Z The existing stratigraphic and structural subdivisions are refined, and temporal constraints indicate two prograde metamorphic events at Yellowknife. Four generations of structures are identified: (1) brittle syn-volcanic, (2) brittle-ductile, late first metamorphism, (3) brittle, post-first metamorphism, pre second metamorphism, and (4) brittle, post second metamorphism, Proterozoic faults. Gold mineralization occurs in P-shears which became dilatant during seismic-aseismic events after a passive ductile state had been achieved, and is reflected at all scales, from hand sample, stope, orebody, ore zone, to mining camp-scales.;Structural studies at Yellowknife, and geochemical analyses of the igneous rocks are consistent with greenstone belt development in a back-arc basin that accreted obliquely onto an older crustal terrain, with emplacement of shoshonitic lamprophyres during late convergence, post-granite. Geochronological work places this framework into; (1) synvolcanic, at 2,683 Ma, (2) syn-I-type batholith, syn first metamorphism at 2,620 Ma, (3) mineralization between 2,620-2,585 Ma, (4) second metamorphism at 2,585 Ma, and (5) Proterozoic dykes.;Ore-related metasomatic alteration is imparted upon structurally and chemically modified volcanic rocks of the Yellowknife Bay Formation. The chemical composition of these rocks, now chlorite schists reveals a fluid history consistent with metasomatic alteration by large volumes of weakly saline, near neutral, CO{dollar}\sb2{dollar}/CH{dollar}\sb4{dollar}-rich fluids at temperatures near 390{dollar}\sp\circ{dollar} {dollar}\pm{dollar} 15{dollar}\sp\circ{dollar}C, and log f{dollar}\sb{lcub}02{rcub}{dollar} near the pyrite-pyrrhotite transition. Gold mineralization was enhanced by fluid-gas unmixing induced by pressure fluctuations, causing periodic excursions in the Eh of the remaining aqueous fluids, resulting in destabilization of soluble gold complexes, changes in mineral phase relationships and chemistries, and shifts in the ... Text Northwest Territories Yellowknife The University of Western Ontario: Scholarship@Western Canada Northwest Territories Yellowknife Yellowknife Bay ENVELOPE(-114.336,-114.336,62.367,62.367) |
institution |
Open Polar |
collection |
The University of Western Ontario: Scholarship@Western |
op_collection_id |
ftunivwestonta |
language |
unknown |
topic |
Geochemistry --Mineralogy |
spellingShingle |
Geochemistry --Mineralogy Webb, David R The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada |
topic_facet |
Geochemistry --Mineralogy |
description |
The existing stratigraphic and structural subdivisions are refined, and temporal constraints indicate two prograde metamorphic events at Yellowknife. Four generations of structures are identified: (1) brittle syn-volcanic, (2) brittle-ductile, late first metamorphism, (3) brittle, post-first metamorphism, pre second metamorphism, and (4) brittle, post second metamorphism, Proterozoic faults. Gold mineralization occurs in P-shears which became dilatant during seismic-aseismic events after a passive ductile state had been achieved, and is reflected at all scales, from hand sample, stope, orebody, ore zone, to mining camp-scales.;Structural studies at Yellowknife, and geochemical analyses of the igneous rocks are consistent with greenstone belt development in a back-arc basin that accreted obliquely onto an older crustal terrain, with emplacement of shoshonitic lamprophyres during late convergence, post-granite. Geochronological work places this framework into; (1) synvolcanic, at 2,683 Ma, (2) syn-I-type batholith, syn first metamorphism at 2,620 Ma, (3) mineralization between 2,620-2,585 Ma, (4) second metamorphism at 2,585 Ma, and (5) Proterozoic dykes.;Ore-related metasomatic alteration is imparted upon structurally and chemically modified volcanic rocks of the Yellowknife Bay Formation. The chemical composition of these rocks, now chlorite schists reveals a fluid history consistent with metasomatic alteration by large volumes of weakly saline, near neutral, CO{dollar}\sb2{dollar}/CH{dollar}\sb4{dollar}-rich fluids at temperatures near 390{dollar}\sp\circ{dollar} {dollar}\pm{dollar} 15{dollar}\sp\circ{dollar}C, and log f{dollar}\sb{lcub}02{rcub}{dollar} near the pyrite-pyrrhotite transition. Gold mineralization was enhanced by fluid-gas unmixing induced by pressure fluctuations, causing periodic excursions in the Eh of the remaining aqueous fluids, resulting in destabilization of soluble gold complexes, changes in mineral phase relationships and chemistries, and shifts in the ... |
format |
Text |
author |
Webb, David R |
author_facet |
Webb, David R |
author_sort |
Webb, David R |
title |
The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada |
title_short |
The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada |
title_full |
The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada |
title_fullStr |
The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada |
title_full_unstemmed |
The Geochemistry And Structural Controls Of Auriferous Shear Zones At Yellowknife, Mackenzie District, Northwest Territories, Canada |
title_sort |
geochemistry and structural controls of auriferous shear zones at yellowknife, mackenzie district, northwest territories, canada |
publisher |
Scholarship@Western |
publishDate |
1992 |
url |
https://ir.lib.uwo.ca/digitizedtheses/2165 https://ir.lib.uwo.ca/context/digitizedtheses/article/3164/viewcontent/NN75342.PDF |
long_lat |
ENVELOPE(-114.336,-114.336,62.367,62.367) |
geographic |
Canada Northwest Territories Yellowknife Yellowknife Bay |
geographic_facet |
Canada Northwest Territories Yellowknife Yellowknife Bay |
genre |
Northwest Territories Yellowknife |
genre_facet |
Northwest Territories Yellowknife |
op_source |
Digitized Theses |
op_relation |
https://ir.lib.uwo.ca/digitizedtheses/2165 https://ir.lib.uwo.ca/context/digitizedtheses/article/3164/viewcontent/NN75342.PDF |
_version_ |
1778531144135868416 |