| Title | Exploring the link between organic matter and Carlin-type gold mineralization: new insights from Yukon deposits |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Pinet, N; Ardakani, O H ; Cesar, J; Petts, D C; Debuhr, C; Sack, P J |
| Source | Geological Survey of Canada, Open File 8895, 2022, 22 pages, https://doi.org/10.4095/330086  Open Access |
| Image |  |
| Year | 2022 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Yukon |
| NTS | 106C/01 |
| Lat/Long WENS | -132.3175 -132.3172 64.1131 64.1128 |
| Subjects | economic geology; geochemistry; fossil fuels; Science and Technology; Nature and Environment; mineral exploration; mineral deposits; sedimentary ore deposits; gold; ore mineral genesis; mineralization;
boreholes; petrographic analyses; pyrobitumen; macerals; hydrocarbons; transport mechanisms; hydrocarbon maturation; bedrock geology; lithology; sedimentary rocks; limestones; mudstones; shales; igneous rocks; intrusive rocks; mafic intrusive rocks;
dykes; core samples; organic geochemistry; Conrad Deposit; Nadaleen Fault; Conrad Anticline; Gametrail Formation; Nadaleen Formation; Ice Brook Formation |
| Illustrations | location maps; cross-sections; lithologic sections; profiles; photographs; plots; photomicrographs; spectra |
| Program | Targeted Geoscience Initiative (TGI-5) Gold ore systems |
| Released | 2022 05 25 |
| Abstract | The link between organic matter and gold in sediment-hosted Carlin-type deposits is controversial. This study aims to tackle this potential link by documenting the occurrence of organic matter in a
single borehole from a Carlin-type gold deposit in Yukon and by considering, in a preliminary way, the spatial and/or temporal relationship between organic matter and gold mineralization. The sedimentary succession hosting the Conrad deposit was
relatively rich in organic matter, possibly related to Archea. Despite the high maturation of samples, the total organic carbon (TOC) content of the limestone unit averages 1.31 wt. % (maximum = 3.18 wt. %). Petrographic observations indicate that
pore and fracture filling pyrobitumen is the dominant organic matter maceral in the studied samples. This type of pyrobitumen was matured after its emplacement, indicating that hydrocarbon fluids cannot have served as an agent for gold transport.
Pyrobitumen disseminated in the rock or associated with stylolites are also documented. The correlation between TOC and Tl (the best proxy for Au) for selected samples and the high As content of pyrobitumen filling pores may suggest a link between
organic matter content and gold deposition, but this was not demonstrated by LA-ICP-MS micro-scale mapping. This study also highlights the challenges of establishing a direct spatial relationship between 'invisible' gold and very small (< 10 µm)
pyrobitumen particles. |
| Summary | (Plain Language Summary, not published)
The link between organic matter and gold in sediment-hosted Carlin-type deposits is controversial. This study aims to tackle this potential link by
documenting the occurrence of organic matter in a single borehole in Yukon. The total organic carbon (TOC) content of the limestone unit averages 1.31 wt. % which demonstrates that the hosting sedimentary unit was relatively rich in organic matter,
possibly related to prokaryote organisms (Archea). Pore and fracture filling pyrobitumen is the dominant type of organic matter. This pyrobitumen was matured after its emplacement, indicating that hydrocarbon fluids cannot have served as an agent for
gold transport. Pyrobitumen disseminated in the rock or associated with stylolites are also documented. The correlation between TOC and Tl for selected samples and the high As content of pyrobitumen filling pores may suggest a link between organic
matter content and gold deposition, but this was not demonstrated by micro-scale mapping. |
| GEOSCAN ID | 330086 |
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