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TitleDelineation of fluid pathways and resulting alteration and breccia signatures of IOCG systems, Great Bear Magmatic Zone, Northwest Territories
AuthorCorriveau, L; Montreuil, J -F; Hayward, N; Enkin, R; Craven, J; Roberts, B; Kerswill, J; Lauzière, K; Brouillette, P; Boulanger-Martel, V; Simard, S
Source38th Annual Yellowknife Geoscience Forum, abstracts of talks and posters; by Palmer, E; Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume vol. 2010, 2010 p. 8-9 (Open Access)
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20110330
MeetingYellowknife Geoscience Forum; Yellowknife; CA; November 16-18, 2010
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS85N; 86C; 86D; 86E; 86F; 86K; 86L
AreaGreat Bear Lake; Lac la Martre; Hottah Lake
Lat/Long WENS-119.0000 -116.0000 67.0000 63.0000
Subjectseconomic geology; fluid migration; mineral deposits; mineral occurrences; iron oxides; copper; gold; alteration; hydrothermal alteration; hydrothermal deposits
ProgramGEM: Geo-mapping for Energy and Minerals, Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)
AbstractThe Geomapping for Energy and Minerals Program and its partners are developing a tectono-hydrothermal-magmatic framework of the Great Bear magmatic zone (NWT) and new vectors, methods and technologies to aid mineral exploration for iron oxide copper-gold (IOCG) deposits in this and other glaciated terrain (Lee et al.; McMartin et al.; Potter et al.). During summer 2010, predictive IOCG alteration to mineralization model and alteration mapping protocol were first tested at the NICO deposit. This magnetite-group IOCG deposit records a cyclic and repeated build-up of high-temperature calcic-iron-potassic alteration and associated mineralization without exposing significant extent of early sodic alteration and subsequent low temperature potassic-iron (hematite) alteration as would predict the model. Delineation of fossil pathways (fault zone, unconformity and/or breccia) for the inferred early and remaining fluids, metals and elements was undertaken across volcanic and metasedimentary rocks, their unconformity, and hypabyssal intrusions using alteration mapping assisted by gamma-ray spectrometry and measurements of magnetic susceptibility. This approach led to the discovery of a 2 by 0.5 km structural breccia corridor with syn- to post-tectonic hydrothermal iron oxide (magnetite to hematite) breccias and U-Th-arsenopyrite±molybdenite anomalies within either silica-, sodic- or potassic-altered metasedimentary rocks. This new system is spatially distinct from the NICO ore zone (which does not contain uranium) and may represent a pathway for both incoming and outcoming fluids involved in the formation of the NICO deposit. The tardi-tectonic tourmaline breccias and the syn- to post-tectonic character of the porphyry dykes in this magnetite-to-hematite group IOCG system, combined with new data from two other IOCG systems studied this summer - the Fab Lake system (studied in collaboration with the Community Government of Gamèti; Potter et al.) and the Cole Lake breccia - provide further constraints on the structural, magmatic and hydrothermal events that led to the IOCG-porphyry continuum documented in the Great Bear magmatic zone. As part of this project and the South Wopmay Bedrock Mapping project (Jackson et al.), two large targets derived from RPM modelling of recent magnetic and radiometric surveys were examined and led to the discovery of hydrothermal systems with iron oxide breccias. The hematite breccias east of Hottah Lake (Montreuil et al.) provide linkages between unconformity uranium prospects in the Hottah terrane (Ootes et al.) and IOCG systems in the Great Bear magmatic zone. The Grouard Lake system is hosted within the Labine Group and display large breccias with amphibole-magnetite alteration, local chalcopyrite occurrences and skarn alteration of stromatolite-bearing carbonate rocks. It bears affinities with magnetite-group IOCG systems. In contrast, the overlying Sloan volcanic rocks, studied both at Grouard lake and across the northern Great Bear magmatic zone, appear to represent an impermeable cap for the development of IOCG environments but a common host for epithermal-type propylitic, argillic and siliceous alteration and mineralization. Beyond the scientific progress reported herein, this talk will also provide an overview of synthesis geological map, IOCG alteration database and revised GIS to come as well as preliminary results of the deep-Earth-probing geophysical surveys, rock physical properties and paleomagnetic method development to study IOCG deposits.