Modelling mineral potential for the Greater Nahanni Ecosystem using GIS-based analytical methods

Abstract

Mineral potential within the Greater Nahanni Ecosystem was modelled in a Geographic Information System (GIS) for four different deposit models: 1) SEDEX -stratiform shale-hosted sedimentary-exhalative Zn-Pb-Ag, 2) 'carbonate-fault' - carbonate-hosted zinc-lead-silver associated with major faults, 3) 'intrusion-related' - includes skarn, rare metals and gemstones), and 4) Carlin-type gold as lode and/or derived placer deposits. This mineral-potential modelling study integrates data collected during two Mineral and Energy Resource Assessment (MERA) projects. The results have contributed to the process of determining the geographic boundaries of the proposed expansion of the Nahanni National Park Reserve. Four mineral potential maps were produced (one for each model) using a data-modified knowledgedriven approach. A weighting scheme, based on integrated mineral deposit and regional geological knowledge, was derived for the various evidence maps for each deposit model. The four potential maps, plus a fifth map of hydrocarbon potential based on the Nahanni MERA 1 assessment, were then combined into a final mineral-potential map using two algorithms: an additive operator and a maximum operator. Prediction plots of the four deposit models show that partial data sets provide reasonable predictions of the remaining known data. Several areas within the study area were identified as having very high mineral potential. For SEDEX zinc-lead-silver type deposits, five areas were identified: A) Howards Pass at the northwest end of the 'zinc corridor'; B) another strand of this corridor northwest of the Cantung mine; C) the Meilleur River Embayment; D) Selena Creek; and E) east of Prairie Creek. For carbonate-fault zinc-lead-silver deposits, five areas are highlighted: F) Prairie Creek; G) Broken Skull Fault; H) Selena Creek; I) Howards Pass; and J) southeast of the Cantung mine. For intrusion-related deposits, three areas stand out: K) Selena Creek; L, M, N) a broad zone intruded by the Tay River plutonic suite including Cantung; and O) O'Grady Batholith. Finally, for the Carlin-type lode and/or placer gold deposits, six areas have high ratings: P) Selena Creek; Q, R, S) a broad linear zone of intrusions dividing and overlapping the 'zinc corridor'; T) surrounding the Mount Hamilton pluton; and U) in and around the O'Grady batholith. High natural gas potential was assessed under the MERA 1 project in the southeast corner of the study area, over the untested Etanda Dome and Twisted Mountain Anticline, as well as over the partially explored Mattson Anticline.