Australian-based Neptune Resources is seeking permission from the New Zealand government to explore for high-grade massive sulphides in the Pacific Ocean.
The massive sulphides are associated with hydrothermal vents on underwater volcanoes north of the country. The vents, or “black smokers,” spout out clouds of mineral-rich fluids at temperatures of 350C or higher. When this hot fluid hits the cold water, minerals are precipitated out to form mineral-rich “chimneys.”
Grab sampling near the Brothers volcano, several hundred kilometres north of East Cape, uncovered a massive sulphide outcrop grading 18% zinc, 15% copper, and 6 grams gold per tonne. This and another submarine volcano, Healy, just to the south, are 200-to-300-metre-deep calderas. Their intact rims act as traps for the mineralized fluid emissions.
Thirteen submarine volcanoes have been discovered in the southern Kermadec arc, which runs for hundreds of kilometres north of North Island.
Six of the volcanoes are active, and it’s thought that the entire Kermadec-Tonga arc may contain another 60 volcanoes.
Initial findings indicate that minerals are deposited in various proportions along the volcanic chain.
Droplets of native mercury have been observed for the first time underwater at a sea-floor hotspring in the Whatakane graben, just off White Island. Whatakane is the only active volcano in the region and is above sea level.
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