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Kermadec Ridge mineral prospecting: Deepsea exploitation without review

10 May 2005

With the discovery of mineral deposits around hydrothermal vents on the Kermadec Ridge in New Zealand's Exclusive Economic Zone, mining is eagerly being pursued.

After decades of extensive commercial fishing, further exploitation of the natural resources of the New Zealand deepsea is being embraced with little consideration of conservation.

A licence issued by the Minister of Energy to the Australian mining company Neptune Resources Limited, provides exclusive rights to prospect for metallic and non-metallic minerals on the seafloor of the Kermadec Ridge.

The extensive Neptune prospecting area is equal to 12 percent of the New Zealand land area, and covers a distance roughly the same as a crow flies between Tauranga and downtown Wellington.
See map top right

Left: A "black smoker" on the Brothers seamount, emitting a hot hydrothermal plume of mineral rich fluid. Liquified metals such as zinc, iron, lead, copper and gold in the 350°C solution mix with 2°C seawater, then precipitate as fine mineral floccuants, and settle on the seafloor as solid metals.

Image courtesy of JAMSTEC

View larger

The Neptune licence, organised by the Crown Minerals division of the Ministry of Economic Development and issued pursuant to the Continental Shelf Act 1964, has not been subjected to the scrutiny of an environmental impact review that would normally be required for similar activity on land.

The deepsea is in a "frontier" situation, lacking regulatory control like that provided by the Resource Management Act which reviews all alterations of the terrestrial environment, and allows submissions from other agencies and the public.

Neptune became interested in prospecting on the Kermadec Ridge following a research expedition in 1999 by government-owned crown research labs, the National Institute of Water and Atmospheric Research (NIWA), and Geological and Nuclear Sciences Ltd (GNS).

The 1999 expedition revealed 13 submarine volcanoes along a 360km stretch of the Kermadec Ridge northeast of White Island.

Grab samples taken from black smoker vents on the Brothers seamount, showed a massive sulphide outcrop containing 18 percent zinc, 15 percent copper, and 6 grammes/tonne of gold.

Deep ocean mining is something new, without proven practices.  The brief 9-page Neptune prospecting licence does not define any method of extraction, and gives the mining company rights over any other person to apply for a subsequent mining licence.

If minerals are dredged, the easiest mining will be on peaks of seamounts with vents, that are the closest to the surface 200m below sea level.

A giant vacuum system has been developed in the United States that will suck mineral ore from a depth of more than 2000m, however, it remains questionable whether this method would be economically feasible because of the high installation and operating cost of the equipment.

Whatever method of extraction is used, it will be 'blind', and indiscriminately destructive.

Lagging conservation in the EEZ .....

After a quarter century of exploitation since the EEZ was formed, there is still no legislation that allows conservation to occur.  The Marine Reserves Bill introduced in Parliament in 2002, which is geared to provide the process for the designation of marine reserves in the EEZ, has not yet been passed.

Ongoing government laboratory research .....

While Neptune Resources carry on prospecting, government funded research is discovering new life forms that exist in the extreme environment of hydrothermal vents.

It is thought that these types of organisms emerged as the earliest form of life on earth.

Hydrothermal vent environments have opened up a field of microbiology that defines new relationships between biological and geological processes.

Organisms so different from anything previously known to science, have taken incredibly diverse forms from one seamount to another.

It is not clear whether the prime motivation of government research is the discovery of new life forms, and protection of them, or the pursuit of exploitable resources.

According to GNS, submarine hot springs within New Zealand's EEZ represent a relatively new branch of science with numerous implications and benefits.

In a joint New Zealand-Japanese expedition in October 2004 on the Brothers seamount, which is within the Neptune Resources licence area, GNS and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) conducted the first probe of a deepsea volcano in New Zealand controlled waters using a manned submersible.

Project leader Cornel de Ronde of GNS said "We saw scores of chimneys, some six metres tall, each containing thousands of tonnes of metal ... fluids were pumping out of the chimneys at 300°C forming dense plumes of black smoke".

During April 2005, the Ring of Fire '05 Expedition, including scientists from GNS, NIWA, and the United States National Oceanic and Atmospheric Administration (NOAA) explored eight Kermadec Ridge volcanoes, at depths of up to 1800m.

Starfish, crabs and 30cm-long mussels live around volcanic seafloor producing hot, mineral-rich water and gases, but key targets of research are the huge mats of bacteria that lie on the ocean floor.

"That's what we're after, the microbiology that is the base of all life," said Dr Alex Malahoff who is the chief executive of GNS and the lead scientist on the expedition.

The seafloor being prospected by Neptune Resources (shaded area above) covers an area of 33,160 sq. km (3,316,000 ha).  The area starts 70 km off the Bay of Plenty coast, about 20 km north of White Island, and extends 423 km to the northeast along the Kermadec Ridge and Havre Trough.  Base map courtesy of NIWA

View larger scale map


New Zealand's massive undersea mountains .....

There are numerous seamounts within the prospecting licence area, including the chain that includes the Rumble and Brothers seamounts.  Scientists have mapped 77 submarine volcanoes in the 2500 km stretch of seafloor between the Bay of Plenty and Tonga.

Terrain model of the 1,300 metre high Brothers seamount, covering 35 sq.km with the peak 1,197 metres below sea level. Image courtesy of NIWA

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Six of the southern Kermadec seamounts are about 2,500 metres (8,260 feet) in height, roughly the same height as Mt Taranaki.

The topographical relief of Rumble III is much greater than Mt Ruapehu, the North Island's highest terrestrial mountain and New Zealand's highest volcanic peak.  Rumble III rises 3,200 metres from it's base 3,400m below sea level, to its' peak 200 metres down.

Mt Ruapehu rises about 2,000m from the Central Plateau 600-900m above sea level, to the peak at 2,797 metres.  Photo: Gary Randorf

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The magnitude of Rumble III rivals the largest New Zealand mountains.  The seven highest peaks, all in the Southern Alps, range from 3,027 to 3,754 metres (Mt Cook) above sea level.

Rumble III covers 300 sq kilometres of seafloor. It is the most active of the southern Kermadec volcanoes, with four hydrophonically detected eruptions between 1958 and 1973. In 1986, steam was seen rising from the ocean with a 500 square metre sulphur slick.  Acoustical recordings found activity again in 1992 when gas bubbles were detected.

Hydrothermal plumes .....

Plumes of hydrothermal fluids containing hot water and gas are continuously expelled from active undersea volcanoes (diagram above).  During the rise of magma from the earth's mantle, water and gases in the magma exsolve with the release of pressure.

View larger diagram

Water and gases rise to cause hydrothermal alteration of the volcanic rock (shown as white) because the fluid is acidic.  The 350°C magmatic fluids which are usually rich in metals, mix with heated seawater, before being forced from the seafloor vent into the cold 2-5°C seawater.

A chemical reaction occurs with metals such as copper, zinc, and gold which are in the 100°C to 350 °C solution, precipitating out as fine mineral floccuants, forming what are referred to as "black smoker" plumes.

They rise, becoming neutrally buoyant, and drift with the ocean current, with particle fallout forming metalliferous sediment on the seafloor.

Below: Hydrothermal plume, Brothers seamount, by permission of JAMSTEC

New Zealand seamounts are regarded as the highest productive area of the southwest Pacific, and a center of global ecosystem production.

Iron and manganese discharged from hydrothermal vents is carried by seafloor currents, to provide nutrients for microscopic organisms on which ocean food chains and fisheries are based.

Copyright © 2005-2010 TerraNature Trust. All rights reserved.

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