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NZ scientists helping frame environmental code for marine mining

Friday 20 Mar 2009 12:00a.m.

NZ scientists helping frame environmental code for marine mining

Maritime scientists, including geologists and biologists, are drafting an environmental code for miners planning on exploiting seafloor minerals.

"We're pulling together a code of conduct that we would like members to adhere to," said Cornel de Ronde, the GNS Science geologist and geochemist who is president of the Honolulu-based International Marine Minerals Society.

The global body sponsors the Underwater Mining Institute and has just released a draft code for environmental management of seafloor mining.

Massive sulphide deposits (SMS) of gold, zinc and copper and other minerals at sites such as New Zealand's Kermadec Arc are attracting prospectors and miners.

British entrepreneur Neptune Minerals has lodged applications for mining licences with the NZ Government over discovered two mineral deposits on the Rumble II West seamount about 400km northeast of Tauranga.

It has described the target sites as "inactive SMS zones".

Dr de Ronde said some miners, such as Nautilus Minerals - which has been seeking gold, copper and zinc in seas off Papua New Guinea - avoided the potentially destructive use of dredging to gather geological samples in fragile sites.

"Nautilus would have a fit if you dredged a site that might have animals, so they use remote-operated vehicles and mini-subs," he said.

But using the alternative of gathering material by submersible to minimise damage was very expensive, Dr de Ronde said.

"For nations like New Zealand, and organisations like the National Institute of Water and Atmospheric research (Niwa), dredging is cheap," he said.

Though it could cause damage, the dredges used were not huge.

"It's easy to say it should not happen, and that it should only be by subs or ROVs - but then the Government needs to give you more money," he said.

The proposed code of conduct envisaged a biological survey of sites before any mining started, he said.

But there was a need for a systematic approach in a rapidly developing sector.

Dr de Ronde said the global recession might provide a breathing space for reviewing the environmental precautions needed in seafloor mining, as mining companies were "cooling their jets".

"In New Zealand, the Government has been sitting on and stalling its oceans policy ... so maybe we have some breathing room".

He was one of a team of New Zealand scientists who joined an American research voyage earlier this month to investigate three key submarine volcanoes along the Kermadec Arc, northeast of White Island, Bay of Plenty.

The seafloor hydrothermal systems and their vents were dynamic and ephemeral, he said.

At the Rumble II West volcano - for which there was not a detailed survey of vent fields in the public domain - no active or dead vents were seen, but the camera being used only covered a few metres of seafloor at a time.

"We just saw rocks and sediment," said Dr de Ronde.

Sensitive tracking of helium isotopes in plumes of mineral-enriched water from hydrothermal systems had previously shown activity at Rumble II West but Dr de Ronde said it was not highly active.

More information waited on detailed water column analysis from data recorded during the voyage.

Massive sulphide (SMS) deposits are left on the sea floor by hydrothermal vents over millions of years as minerals in the Earth's crust dissolve in super-heated fluids then drop to the seafloor when they emerge into cold seawater.

Neptune has claimed that deposits of gold, silver copper and zinc, worth up to $US2000/tonne ($NZ3700/tonne) along the Kermadec Arc can be mined for a combined capital and operating cost of less than $US162/tonne.

Metallurgical testing done for the company on a composite sample from its initial Kermadec exploration in 2006 showed an average of 11.2 parts per million of gold, 122ppm of silver, 8.1 percent copper, 0.5 percent lead and 5 percent zinc.
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