Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon

Epithermal veins of the southern Dawson Range, Yukon, are hosted by a wide range of lithologies, ranging from Proterozoic metasedimentary rocks to Late Cretaceous volcanic rocks. Both the 105 Ma calc-alkaline Mount Nansen volcanic group and the 70 Ma shoshonitic Carmacks volcanic group also host sma...

Full description

Bibliographic Details
Main Author: Smuk, Katherine A.
Other Authors: Williams-Jones, A. E. (advisor), Francis, D. (advisor)
Format: Thesis
Language:English
Published: McGill University 1998
Subjects:
Online Access:http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21643
id ftcanadathes:oai:collectionscanada.gc.ca:QMM.21643
record_format openpolar
spelling ftcanadathes:oai:collectionscanada.gc.ca:QMM.21643 2023-05-15T15:53:36+02:00 Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon Smuk, Katherine A. Williams-Jones, A. E. (advisor) Francis, D. (advisor) Master of Science (Department of Earth and Planetary Sciences.) 1998 application/pdf http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21643 en eng McGill University alephsysno: 001656230 proquestno: MQ50883 Theses scanned by UMI/ProQuest. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21643 All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. Geology Electronic Thesis or Dissertation 1998 ftcanadathes 2014-02-16T01:06:18Z Epithermal veins of the southern Dawson Range, Yukon, are hosted by a wide range of lithologies, ranging from Proterozoic metasedimentary rocks to Late Cretaceous volcanic rocks. Both the 105 Ma calc-alkaline Mount Nansen volcanic group and the 70 Ma shoshonitic Carmacks volcanic group also host small Au-Cu(+/-Mo) porphyry deposits. Although the structurally-controlled mineralized veins are spatially associated with Mount Nansen felsic dykes, K/Ar dates for sericitically and argillically altered dykes proximal to mineralization are --70 Ma, indicating thermal resetting by a Carmacks-age hydrothermal event. These altered dykes are depleted in Na, Pb, Zn, and Cu, but enriched in As and Sb, relative to unaltered dykes. The base metal-rich epithermal veins are transitional between classic low and high sulphidation deposit types. They were deposited by a Na +-dominated fluid with an average salinity of ~6 wt.% NaCl equiv., a temperature of --300°C, a high S2-- (0.20 m) concentration, and significant CO2 (~1 mol.%). The isotopic composition of inclusion fluids (delta18O = ~--10‰; deltaD = ~--95‰) indicate that the hydrothermal fluid was dominantly meteoric, but a magmatic fluid contribution is suggested by the heavy delta18O, delta34S values close to zero, and the high temperatures, salinities, SigmaS, and CO2. The isotopic compositions of Pb in galena correlate well with initial whole rock values for Carmacks volcanic rocks, suggesting that much of the Pb, and other base metals, were leached from the Carmacks volcanics. As and Sb, and by inference Au, are not locally derived. The log fO2 and pH conditions of mineralization were between --34 and --36, and 3--5, respectively. The deposition of base metal sulphides appears to have been caused by an increase in pH due to the consumption of H+ during the alteration of the host rocks. The decrease in SigmaS caused by sulphide precipitation destabilized Au(HS)2-- complexes, precipitating native gold. The mineralization was caused by the hydrothermal circulation of acidic, meteoric water, probably driven by Carmacks magmatism. Thesis Carmacks Dawson Yukon Theses Canada/Thèses Canada (Library and Archives Canada) Carmacks ENVELOPE(-136.293,-136.293,62.088,62.088) Dawson Range ENVELOPE(-138.337,-138.337,62.583,62.583) Mount Nansen ENVELOPE(163.167,163.167,-74.883,-74.883) Yukon
institution Open Polar
collection Theses Canada/Thèses Canada (Library and Archives Canada)
op_collection_id ftcanadathes
language English
topic Geology
spellingShingle Geology
Smuk, Katherine A.
Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon
topic_facet Geology
description Epithermal veins of the southern Dawson Range, Yukon, are hosted by a wide range of lithologies, ranging from Proterozoic metasedimentary rocks to Late Cretaceous volcanic rocks. Both the 105 Ma calc-alkaline Mount Nansen volcanic group and the 70 Ma shoshonitic Carmacks volcanic group also host small Au-Cu(+/-Mo) porphyry deposits. Although the structurally-controlled mineralized veins are spatially associated with Mount Nansen felsic dykes, K/Ar dates for sericitically and argillically altered dykes proximal to mineralization are --70 Ma, indicating thermal resetting by a Carmacks-age hydrothermal event. These altered dykes are depleted in Na, Pb, Zn, and Cu, but enriched in As and Sb, relative to unaltered dykes. The base metal-rich epithermal veins are transitional between classic low and high sulphidation deposit types. They were deposited by a Na +-dominated fluid with an average salinity of ~6 wt.% NaCl equiv., a temperature of --300°C, a high S2-- (0.20 m) concentration, and significant CO2 (~1 mol.%). The isotopic composition of inclusion fluids (delta18O = ~--10‰; deltaD = ~--95‰) indicate that the hydrothermal fluid was dominantly meteoric, but a magmatic fluid contribution is suggested by the heavy delta18O, delta34S values close to zero, and the high temperatures, salinities, SigmaS, and CO2. The isotopic compositions of Pb in galena correlate well with initial whole rock values for Carmacks volcanic rocks, suggesting that much of the Pb, and other base metals, were leached from the Carmacks volcanics. As and Sb, and by inference Au, are not locally derived. The log fO2 and pH conditions of mineralization were between --34 and --36, and 3--5, respectively. The deposition of base metal sulphides appears to have been caused by an increase in pH due to the consumption of H+ during the alteration of the host rocks. The decrease in SigmaS caused by sulphide precipitation destabilized Au(HS)2-- complexes, precipitating native gold. The mineralization was caused by the hydrothermal circulation of acidic, meteoric water, probably driven by Carmacks magmatism.
author2 Williams-Jones, A. E. (advisor)
Francis, D. (advisor)
format Thesis
author Smuk, Katherine A.
author_facet Smuk, Katherine A.
author_sort Smuk, Katherine A.
title Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon
title_short Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon
title_full Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon
title_fullStr Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon
title_full_unstemmed Metallogeny of epithermal gold and base metal veins of the southern Dawson Range, Yukon
title_sort metallogeny of epithermal gold and base metal veins of the southern dawson range, yukon
publisher McGill University
publishDate 1998
url http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21643
op_coverage Master of Science (Department of Earth and Planetary Sciences.)
long_lat ENVELOPE(-136.293,-136.293,62.088,62.088)
ENVELOPE(-138.337,-138.337,62.583,62.583)
ENVELOPE(163.167,163.167,-74.883,-74.883)
geographic Carmacks
Dawson Range
Mount Nansen
Yukon
geographic_facet Carmacks
Dawson Range
Mount Nansen
Yukon
genre Carmacks
Dawson
Yukon
genre_facet Carmacks
Dawson
Yukon
op_relation alephsysno: 001656230
proquestno: MQ50883
Theses scanned by UMI/ProQuest.
http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21643
op_rights All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
_version_ 1766388716349161472