| Titre | Gold deposits of the world-class Timmins-Porcupine Camp, Abitibi Greenstone Belt, Canada |
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| Auteur | Dubé, B; Mercier-Langevin, P; Ayer, J; Pilote, J -L; Monecke, T |
| Source | Geology of the world's major gold deposits and provinces; par Sillitoe, R H (éd.); Goldfarb, R J (éd.); Robert, F (éd.); Simmons, S F (éd.); Society of Economic Geologists, Special Publication no. 23,
2020 p. 53-80, https://doi.org/10.5382/SP.23.03 |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190292 |
| Éditeur | Society of Economic Geologists |
| Édition | 1 |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.5382/SP.23.03 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Ontario |
| SNRC | 42A/06; 42A/11 |
| Région | Timmins |
| Lat/Long OENS | -81.5000 -81.0000 48.7500 48.2500 |
| Sujets | gisements minéraux; or; ceintures de roche verte; genèse des minerais; minéralisation; contrôles des minerais; discordances; quartz; carbonate; tourmaline; pyrite; filons; ankérite; antécédents
géologiques; sédimentation; antécédents tectoniques; métamorphisme; déformation; système hydrothermal; métasomatose; altération; intrusions; dynamique des fluides; roches hôtes; géologie du substratum rocheux; caractéristiques structurales; failles;
plis; lithologie; roches ignées; roches volcaniques; basaltes; komatiites; roches intrusives; Archéen; Ceinture d'Abitibi Greenstone ; Zone de faille de Destor-Porcupine ; Assemblage de Timiskaming ; géologie économique; tectonique; stratigraphie;
Sciences et technologie; Nature et environnement; Précambrien |
| Illustrations | cartes géolscientiques généralisées; tableaux; cartes géochronologiques; coupes schématiques; photographies; photomicrographies |
| Programme | Initiative géoscientifique ciblée (IGC-5) Systèmes minéralisés aurifères |
| Diffusé | 2020 12 11 |
| Résumé | (disponible en anglais seulement)
The Timmins-Porcupine camp, with >2,190 metric tons Au (70.5 Moz) produced between 1906 and 2019, is the world's largest Archean orogenic gold camp. The gold
deposits of the camp are distributed over ~50 km of strike length along the Destor-Porcupine fault zone. This includes the world-class Hollinger-McIntyre and Dome deposits, which represent archetypal examples of large orogenic quartz-carbonate gold
systems. The Dome deposit, where the ore is centered on a folded unconformity between Tisdale volcanic rocks and Timiskaming sedimentary units, also illustrates the spatial relationship between large gold deposits and a regional unconformity.
Ore-forming hydrothermal activity in the camp spanned a prolonged period of time, as illustrated by early-stage, low-grade ankerite veins formed between ca. 2690 and 2674 Ma. This was prior to or very early relative to the development of the regional
unconformity and sedimentation of the Timiskaming assemblage, and subsequent main-stage gold deposition. The bulk of the gold in the district is younger than the Three Nations Formation of the upper part of the Timiskaming assemblage (i.e., less than
or equal to 2669 ± 1 Ma) and was deposited syn- to late-main phase of shortening (D3) in the Timmins-Porcupine camp from about 2660 to 2640 ± 10 Ma. The early carbonatization represents a significant early-stage hydrothermal event in the formation of
large structurally controlled gold deposits such as Dome and illustrates the protracted nature of the large-scale CO2-rich metasomatism occurring before and during gold deposition.
Ores in the Timmins-Porcupine camp mainly consist of networks of
steeply to moderately dipping fault-fill quartz-carbonate ± tourmaline ± pyrite veins and associated extensional, variably deformed, shallowly to moderately dipping arrays of sigmoidal veins hosted in highly carbonatized and sericitized rocks and
formed during main regional shortening (D3). In contrast, at the Timmins West mine, the Thunder Creek and 144 GAP deposits are early- to syn-Timiskaming intrusion-associated deposits that slightly predate to overlap the main phase of D3 horizontal
shortening in which the associated intrusions mainly played a passive role as an older mechanical and chemical trap rock.
The formation of the gold deposits of the Timmins-Porcupine camp is due to several key factors. The Destor-Porcupine fault
zone represents a deeply rooted first-order structure and tapped auriferous metamorphic fluids and melts from the upper mantle-lower crust. The fault zone has channeled large volumes of auriferous H2O-CO2-rich fluids to the upper crust late in the
evolution of the belt. Several of the gold deposits of the camp are spatially associated with the regional Timiskaming unconformity. The current level of erosion is deep enough to expose the unconformity and to maximize the chance of discovering the
quartz-carbonate style of orogenic deposits or the associated hydrothermal footprint, but also allowed for preservation of at least part of the gold deposits that are mainly hosted in the highly reactive Fe-rich basalt of the Tisdale assemblage.
Additional key factors include the presence of komatiitic and/or basaltic komatiite flows, competent pre- and syn-Timiskaming subalkaline and alkaline intrusions that predate the main phase of shortening, and the occurrence of a flexure in the trace
of the Destor-Porcupine fault zone that may have further facilitated and focused the ore-forming fluid upflow in the most endowed part of the camp. The complex structural and rheological discontinuities, competency contrasts, and early-stage folds
with associated fracture and fault networks in the camp provided highly favorable ground-preparation conditions. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'IGC-5 Or est un programme fédéral de collaboration qui fournit à l'industrie les connaissances géoscientifiques et les techniques novatrices
de prochaine génération pour mieux détecter les gîtes minéraux enfouis, réduisant ainsi certains risques liés à l'exploration. Le camp minier d'or de Timmins-Porcupine de la partie nord-ouest de l'Ontario est le plus grand camp minier d'or orogénique
de l'Archéen. Plusieurs événements ont contribué à sa formation, incluant: 1) une zone de faille majeure de compressions de premier ordre; 2) une discordance régionale et des bassins d'extension connexes dont les conditions de la croûte terrestre ont
favorisé la circulation des fluides minéralisateurs; 3) la présence de masses intrusives compétentes avant la phase principale de déformation; 4) la présence d'une structure de dilatation le long de la zone de la faille qui a concentré la circulation
des fluides minéralisateurs; et 5) un cadre géologique caractérisé par des discontinuités structurales et rhéologiques complexes. Enfin, un héritage en or unique de la partie sud de l'Abitibi, combinée au processus minéralisateur, peut constituer un
facteur important. |
| GEOSCAN ID | 315421 |
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