1 CSEG RECORDER FEBRUARY 2020 SPECIAL COORDINATORS: JEAN LEGAULT & OLIVER KUHN, TECHNICAL EDITOR: RUTH PEACH Applied geophysics in a very deep mine context: Example of the >3 km deep, LaRonde Penna mine, Abitibi Greenstone Belt, Quebec LIZHEN CHENG 1 , XUEPING DAI 1 , MAMADOU-CHERIF DIALLO 1 , CHONG LIU 1 , NACIM FOUDIL-BEY 1 , JONATHAN COLLINS 2 , PIERRE BÉRUBÉ 2 , RICHARD DUBUC 3 , DAVID FORTIN 3 , MARC LEGAULT 4 , PATRICK MERCIER-LANGEVIN 5 , BAHMAN ABBASSI 1 1 UNIVERSITÉ DU QUÉBEC EN ABITIBI-TÉMISCAMINGUE, 445 BOUL. DE L’UNIVERSITÉ, ROUYN- NORANDA, QUEBEC, CANADA, J9X 5E4. 2 ABITIBI GEOPHYSIQUE,1740 CHEMIN SULLIVAN, SUITE 1400, VAL-D’OR, QUEBEC, CANADA J9P 7H1. 3 LARONDE DIVISION, AGNICO EAGLE MINES LIMITED., 10200 ROUTE DE PREISSAC, ROUYN- NORANDA, QUEBEC, CANADA, J0Y 1C0. 4 CÉGEP DE L'ABITIBI-TÉMISCAMINGUE. 425, BOULEVARD DU COLLÈGE, ROUYN-NORANDA, QUEBEC, CANADA, J9X 5E5. 5 GEOLOGICAL SURVEY OF CANADA, 490 RUES DE LA COURONNE, QUEBEC, QC G1K 9A9, CANADA. Abstract As mines are operating at ever-greater depths, cutting-edge, economically viable technologies must be developed to help explore for, and accurately locate, potentially mineralized bodies. A promising way to meet the challenges of exploring for mineral resources at great depth, and reduce the environmental impact of exploitation, is to take advantage of existing mining installations and tailings facilities to conduct underground-based geophysical surveys. The University of Quebec in Abitibi-Témiscamingue, the Cégep de l’Abitibi-Témiscamingue, and their industry partners Abitibi Géophysique Inc. and Agnico Eagle Mines Ltd., have designed and performed a series of innovative geophysical exploration experiments at a depth of 3 km below surface. Results of 3D modeling, field-testing, and an underground survey at the LaRonde Penna mine indicate that this technique greatly improves the chances of detecting mineralized zones that would probably not be detected from surface surveys. The knowledge gained from this unique experiment has proven invaluable for furthering deep geophysical exploration and development.