Giant Black Smoker Retrieved From Abyss

The find is part of a voyage of discovery by the RV Franklin to probe the mysteries of vast hydrothermal systems on the ocean floor, spewing out plumes of superheated mineral-rich fluids like those which formed giant ore bodies like Mt Isa and Broken Hill over a billion years ago.

As well as studying ore-forming processes, the researchers are hunting for "extremophile" microbes endowed with the natural ability to process minerals at high temperature. Their aim is to help make Australia's $37 billion mineral export industry cleaner, greener, safer and more competitive.

Their search is being conducted in an eerie landscape nearly two kilometres below the surface of the ocean. Smoking undersea chimneys pump mineral fluids from deep in the earth's crust into the surrounding seawater, shattered mineral columns resemble ancient ruins, and undersea hills are mantled in snow-white carpets of bacteria and organic hydrates - compounds which can only exist at the extreme pressures of the deep ocean.

During the search, Franklin's dredge snagged the huge chimney of a black smoker, a tubular encrustation of minerals that would make a prized museum display, according to expedition leader Dr Ray Binns, of CSIRO Exploration & Mining.

"Our dredge must have fallen right over its top. This anchored the ship for over an hour but it finally broke off at the base," he says.

"Luckily for us it got wedged into the dredge frame on its point of balance, so it stayed there while we winched it all the way up to the ship. It proved to be 2.7 metres long, 80 cm in diameter at the base, and weighed some 800 kg in water at least, closer to a tonne in air.

"It must have been an actively venting chimney, for live snails dropped into the dredge bag, and fluid dripping from it was quite acidic, although there was no characteristic smell of rotten eggs (from hydrogen sulfide gas) often found with smaller chimneys.

"Our first examination indicated it was teeming with bacteria and archaea (very ancient and primitive life forms). The microbiologists aboard were delighted," Dr Binns says

A major goal of the expedition is to identify particular microbes that can be used to process minerals on dry land, and so develop more efficient and cleaner ways to win metals, explains project designer Dr Dave Dekker of CSIRO Exploration & Mining.

"We believe that microbes such as these deep sea bugs may enable Australia's miners to exploit lower grade ore deposits, extract metals more cheaply, clean up waste streams and may even improve mine safety."

Microbiologist Dr Peter Franzmann of CSIRO Land & Water says that the mineral-mining bugs are possibly relatives of some of the earliest forms of life to emerge on the planet, more than three billion years ago.

"Back then, conditions were similar to what we now see in these seafloor hydrothermal vents - high temperatures, lots of volcanic activity, darkness, with the nutrients to sustain life pouring out of the earth itself."

Dr Binns says the recovered chimney is "a particularly handsome specimen, but rather fragile, consisting mainly of the mineral known as sphalerite (zinc sulfide)".

"The Franklin's crew managed to slide it out of the yoke without breaking it using the ship's crane. For the time being we've got it swathed in cheesecloth provided by the ship's cook, kept damp with seawater and wrapped with plastic".

The RV Franklin berthed in Rabaul last Thursday (4 May) and is now moving from the Bismarck Sea into the Pacific with another research team. Led by Dr Brent McInnes of CSIRO Exploration & Mining, scientists from Australia, Papua New Guinea, New Zealand and USA are visiting submarine volcanoes in the Tabar-Lihir-Tanga-Feni and Solomon Island chains.

Besides studying the volcanoes themselves, this team is also searching for undersea hot-springs that might be depositing gold and other minerals. The chances of finding such springs are good, for the nearby Ladolam deposit on the island of Lihir is the largest and youngest epithermal gold deposit in the world.

The geological setting of the volcanoes targeted by the second cruise is different from those of the Bismarck Sea, so any further discoveries will expand the range of modern ore-forming environments that scientists can use to understand how ore bodies formed in the past. The outcomes will include better strategies for future mineral exploration on land, which is becoming harder all the time, now that prospectors have found most of the ore bodies that crop out at the surface.