| Title | Mineral markers of porphyry processes: regional and local signatures of porphyry prospectivity |
| Download | Downloads |
| |
| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Chapman, J B ;
Plouffe, A; Jackson, S E; Ryan, J J; Ferbey, T |
| Source | TGI 4 - Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation; by Rogers, N (ed.); Geological Survey of Canada, Open File 7843, 2015 p. 521-534, https://doi.org/10.4095/296487  Open Access |
| Links | Canadian Database of Geochemical Surveys, downloadable
files
|
| Links | Banque de données de levés géochimiques du Canada,
fichiers téléchargeables
|
| Image |  |
| Year | 2015 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This publication is contained in TGI 4 - Intrusion Related
Mineralisation Project: new vectors to buried porphyry-style mineralisation |
| File format | pdf |
| Province | Yukon |
| NTS | 105D; 105E; 105L; 115A; 115H; 115I |
| Area | Whitehorse; Carmacks |
| Lat/Long WENS | -138.0000 -134.5000 63.0000 60.5000 |
| Subjects | economic geology; tectonics; porphyry deposits; porphyry copper; mineral exploration; mineralization; tungsten; molybdenum; copper; gold; magmatic deposits; magmatic rocks; zircon; tourmaline; indium;
Sisson deposit; Nashwaak Granite; Mesozoic; Jurassic |
| Illustrations | location maps; photographs; plots; ternary diagrams; photomicrographs |
| Program | Targeted Geoscience Initiative (TGI-4) Intrusion/Porphyry Ore Systems |
| Released | 2015 06 11; 2023 03 17 |
| Abstract | Porphyry-style mineralisation occurs chiefly as a consequence of the release of large volumes of metal-bearing aqueous brine during the cooling and crystallization of plutonic and intrusive magmatic
systems. In addition to the metals of economic interest, many additional elements are preferentially incorporated into the aqueous fluid during its segregation from the parent magma, or are gained from interactions with proximal county rocks. During
its segregation, pooling and ascent, this magmatic-hydrothermal fluid also deposits many of its elemental components; either through direct precipitation of new minerals or by metasomatic interactions with existing minerals.
The elemental and
mineralogical signatures of each of these fluid generation, mineral precipitation and hydrothermal alteration processes may be recorded within the resultant mineral residues at each stage, and will likely reflect a complex and evolving suite of
physicochemical influences that operated during the formation of each ore deposit. Modern analytical methods are increasingly able to interrogate these signatures at smaller scales and lower cost, thus bringing effective and efficient mineral
analysis within the scope of even small scale mineral exploration programs. In this presentation we will discuss a suite of mineralogical and mineral chemistry studies performed in the last few years as part of the Government of Canada's Geomapping
for Energy and Minerals and Targeted Geoscience Initiative Programs. All are targeted toward increasing both the efficiency and effectiveness of porphyry mineral exploration within Canada.
Late Triassic to early Jurassic plutonic rocks of British
Columbia are genetically associated with the great majority of Canada's porphyry copper, molybdenum and gold resources and producing mines, forming the 'Copper Pine of the Cordillera'. Within Yukon they host the sole currently producing copper-gold
mine in the territory. However, additional exploration activity within Yukon has been largely unsuccessful and, away from Minto mine itself, the metal endowment of Triassic- Jurassic plutonic suites remains uncertain. In order to assess the
prospectivity of these rocks and to provide a tool whereby future exploration in the region could be focused, our study examined the Ce4+/Ce3+ composition of igneous zircon samples taken from across the district, as well as comparative samples from
the late Cretaceous Casino deposit. Our results indicate that physicochemical conditions which prevailed during formation of the Minto deposit occurred widely across the Yukon Triassic-Jurassic plutonic suites, but that mineralisation may have
occurred at much deeper crustal depths than expected for 'typical' porphyry deposits.
Within central and southern British Columbia, many known porphyry deposits are partly or entirely covered by Quaternary glacial sediments. However, a suite of
indicator minerals in till in areas around these deposits can detect diagnostic mineralogical signatures of porphyry mineralisation many kilometres down-ice of the deposit location. In addition to indicator minerals, chemical analysis of the till can
be used to fingerprint the type of mineralisation expected. A combination of till geochemistry and mineralogy might potentially be developed to provide preliminary information on the metal endowment of a buried mineralized body. At the Woodjam
porphyry Cu-Au±Mo deposits of central BC, we can demonstrate that mineralogical complexity in bedrock tourmaline minerals - associated with both ore-forming and distal hydrothermal alteration processes - can be detected in surficial materials,
providing context and refined detail to the broad exploration target produced.
Within porphyry and greisen-style tin-tungsten-base metal systems of the Canadian Appalachian district, zones of high indium content are significant exploration
targets. However, despite apparent bulk mineralogy and base metal grade similarities between indium-rich and -poor ore, these zones do not occur evenly throughout the region. As a part of a detailed inventory and mineralogical assessment of indium
distribution within southern New Brunswick and Nova Scotia we have identified distinct mineralogical fingerprints associated with indium enrichment. |
| Summary | (Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience
knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This volume summarises research activities completed under the TGI 4 Intrusion Related Mineralisation Project that
focused on porphyry-style ore systems related to the Cu- and Cu-Mo deposits of South-Central British Columbia and the Sn-W-Mo-In deposits in New Brunswick, Nova Scotia and Newfoundland. |
| GEOSCAN ID | 296487 |
|
|