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The decision, made by the OceanaGold board of directors, was announced over the weekend.
The company said Mr Holmes was a mining engineer with more than 30 years of experience working all over the world, including New Zealand, Australia, Asia, North and South America.
He joined OceanaGold as chief operating officer in 2012.
"Michael is a very experienced industry veteran with a deep knowledge of the OceanaGold business," OceanaGold chairman Ian Reid said.
"He has a proven track record as a skilled and capable leader and has the full confidence and support of the board, as well as the commitment and alignment of the executive team."