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TitleGold deposits of the world-class Timmins-Porcupine Camp, Abitibi Greenstone Belt, Canada
 
AuthorDubé, B; Mercier-Langevin, P; Ayer, J; Pilote, J -L; Monecke, T
SourceGeology of the world's major gold deposits and provinces; by Sillitoe, R H (ed.); Goldfarb, R J (ed.); Robert, F (ed.); Simmons, S F (ed.); Society of Economic Geologists, Special Publication no. 23, 2020 p. 53-80, https://doi.org/10.5382/SP.23.03
Year2020
Alt SeriesNatural Resources Canada, Contribution Series 20190292
PublisherSociety of Economic Geologists
Editionfirst edition
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceOntario
NTS42A/06; 42A/11
AreaTimmins
Lat/Long WENS -81.5000 -81.0000 48.7500 48.2500
Subjectseconomic geology; tectonics; stratigraphy; Science and Technology; Nature and Environment; mineral deposits; gold; greenstone belts; ore mineral genesis; mineralization; ore controls; unconformities; quartz; carbonate; tourmaline; pyrite; veins; ankerite; geological history; sedimentation; tectonic history; metamorphism; deformation; hydrothermal systems; metasomatism; alteration; intrusions; fluid dynamics; host rocks; bedrock geology; structural features; faults; folds; lithology; igneous rocks; volcanic rocks; basalts; komatiites; intrusive rocks; Archean; Timmins-Porcupine Camp; Abitibi Greenstone Belt; Destor-Porcupine Fault Zone; Hollinger-McIntyre Deposit; Dome Deposit; Timiskaming Assemblage; Three Nations Formation; Timmins West Mine; Thunder Creek Deposit; 144 GAP Deposit; Precambrian
Illustrationsgeoscientific sketch maps; tables; geochronological charts; schematic sections; photographs; photomicrographs
ProgramTargeted Geoscience Initiative (TGI-5) Gold ore systems
Released2020 12 11
AbstractThe 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.
Summary(Plain Language Summary, not published)
The TGI-5 Gold is a collaborative federal geoscience program that provides industry with the next generation of knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. The Timmins-Porcupine gold camp of NW Ontario is the largest Archean orogenic gold camp. A multitude of events were involved in the formation of the district including: 1) a first order major compressional fault zone; 2) a regional unconformity and associated extensional, syn-orogenic basins that provided favorable crustal conditions to ore-forming fluids circulation; 3) presence of pre-main phase of deformation competent intrusions; 4) presence of dilational jog along the fault zone that helped focus ore-forming fluids circulation; and 5) a geological setting characterized by complex structural and rheological discontinuities. Finally, the unique gold endowment of the Southern Abitibi in addition to ore-forming process may be a major factor.
GEOSCAN ID315421

 
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