Horan's planned retirement comes after 10 years in the role. He oversaw Marengo's ASX listing and the game-changing acquisition of its Yandera copper-molybdenum-gold project in Papua New Guinea, which is close to a successful feasibility study milestone after years of diligent exploration.
Marengo managing director and chief executive officer Les Emery said it was fitting that highly experienced Gignac would take over the chairmanship from Horan at the annual general meeting in November.
Gignac, the existing chairman of St Andrew Goldfields, was in this role for Andean Resources before it got taken over by Goldcorp for $3.6 billion. He was president and CEO for Cambior from its formation in 1986 until its acquisition by IAMGOLD Corporation in 2006.
As president of private-owned consultancy G Mining Services, he has managed feasibility studies and mine development for projects across North America, South America, West Africa and Eastern Europe.
Marengo also said Gignac was involved in the development and operation of some 14 mines throughout the Americas over his career so far.
"Louis' track record and career speaks for itself, and he brings to Marengo an extensive global contact network and remarkable depth of experience at the highest levels of the international mining industry," Emery said.
"We are delighted to have secured someone of Louis' calibre to take over the chairmanship of Marengo and we believe it is entirely fitting that our new chairman should be based in Canada, following the recent announcement of our plans to re-domicile the company to Canada."
Horan also had some parting words.
"After 10 years at the helm of Marengo, I believe the time is right to hand over the chairmanship and I am very pleased to be passing the baton to someone with an impressive depth of corporate and technical experience in the global mining industry.
"I am confident that Louis will make an invaluable contribution to the company as we move towards financing and development of Yandera, and I wish him and the rest of the board and company well for the future.
"This is a pivotal moment in Marengo's history as we embark on the next chapter of growth and prepare ourselves to become a leading international copper producer at Yandera."
Marengo is on track to complete the feasibility study this month. It has been delayed for several months due to some unexpectedly good and often shallow high-grade hits from infill drilling this year.
The Yandera project is 95km southwest of the provincial capital of Madang and is initially expected to produce 100,000 tonnes of contained copper plus 150,000t of contained molybdenum a year over a 20-year life, but there is plenty of scope for expansion or an extended mine life.