The application of rapid potential field methods for the targeting of IOCG mineralisation based on physical property data,Great Bear magmatic zone,Canada |
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| Institution: | 1. Geological Survey of Canada, 605 Robson Street, Vancouver, BC V6B 5J3, Canada;2. Geological Survey of Canada, P.O. Box 6000, Sidney, BC V8L 4B2, Canada;3. Geological Survey of Canada, 490 rue de la Couronne, Québec, QC G1K 9A9, Canada;4. INRS-ETE, 490 rue de la Couronne, Québec, QC G1K 9A9, Canada;5. Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada;1. Institut National de la Recherche Scientifique, Centre Eau, Terre et Environnement (INRS-ETE), 490 de la Couronne, Quebec City, QC, Canada, G1K 9A9;2. Université Laval, Département de Géographie, Faculté de foresterie, de géographie et de géomatique, Pavillon Abitibi-Price, 2405, rue de la Terrasse, Local 3137, Quebec City, QC, Canada, G1V 0A6;3. Defence Research and Development Canada – Valcartier, 2459 Pie-XI Blvd. North, Quebec City, QC, Canada, G3J 1X5;1. School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA 5005, Australia;2. BHP Olympic Dam, Adelaide, SA 5001, Australia;3. School of Mathematical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia;4. ARC Centre of Excellence in Ore Deposits, School of Natural Sciences, University of Tasmania, Hobart, TAS 7005, Australia |
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| Abstract: | New techniques for the integration of gravity and aeromagnetic data through rock physical property relationships are tested for the rapid location of potential iron oxide–copper–gold (IOCG) exploration targets across the Great Bear magmatic zone (GBMZ). These techniques are based on the recognition of coincident or near-offset magnetic and gravity anomalies associated with IOCG deposits, resulting from their intense and combined iron-oxide and alkali alteration. In the GBMZ, the NICO (Au–Co–Bi–Cu) deposit is an atypical magnetite-group IOCG hosted within an intensely hydrothermally-altered metasedimentary sequence. Prospectivity maps for the NICO area are derived from the integration of high-resolution aeromagnetic and surface gravity data with physical property measurements of magnetic susceptibility and density. Method 1 combines the pseudo-gravity (derived from the aeromagnetic data) and Bouguer gravity data to determine the locations of superimposed high anomalies. Method 2 estimates the apparent susceptibility and density subsurface distribution based on vertical prism models of the magnetic and gravity data. The apparent susceptibility data are transformed to apparent density using physical property relationships. The two apparent density datasets are then combined to determine the location of coincident magnetic and gravity derived anomalies. The results of these methods are supported by, and compared with, similar prospectivity maps generated through weights of evidence techniques. At NICO, the prospectivity maps accurately locate the deposit and nearby occurrences. Despite the lower resolution of the regional gravity data, application of the techniques across the GBMZ is successful at locating mineralised IOCG systems including the magnetite-group systems at Grouard, Fab, DeVries and Cole Lake, the magnetite to hematite-group systems of the Port Radium-Echo Bay district, and has highlighted possible targets for future exploration. |
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