An international science team has witnessed the dramatic birth of a new volcanic island in the Pacific.
The rare event was witnessed by scientists during a research expedition to the Solomon Islands on the CSIRO research vessel Franklin.
The Franklin is returning to Darwin after two successful cruises looking at volcanic activity and associated mineral formation in the Bismarck Sea and the Pacific. From the first leg of the expedition, scientists are bringing back a world record size "black smoker" chimney from the bottom of the Bismarck Sea.
On the second leg of the cruise, scientists found the Kavachi seamount had entered a new phase of island-building eruptive activity after 9 years of apparent dormancy.
"We arrived at the seamount site to find waves breaking on the volcanic peak. Violent eruptions were taking place every five minutes", recounts expedition Chief Scientist Brent McInnes of CSIRO Exploration and Mining. The eruptions ejected molten lava up to 70 m above sea level, and sulfurous steam plumes mushroomed to 500 m. At night, the red glow of the explosive eruptions produced a spectacular fireworks display.
"We were able to approach to within 750 m of the erupting centre. We found that the volcano had grown dramatically since it was last surveyed in 1984," says Neil Cheshire, Master of the Franklin.
"Using Franklin to systematically sample freshly formed volcanic rocks from the flanks of an erupting submarine volcano is an unprecedented opportunity in the field of geology," says Professor Richard Arculus of the Australian National University Department of Geology.
The scientists were surprised by the discovery of sulfide-rich volcanic samples similar to gold ores from other volcanic centres like the Lihir mining operation in Papua New Guinea, another site investigated by the CSIRO-led team.
The effect of the eruptions on the chemistry and turbidity of the ocean surrounding the Kavachi volcano was monitored by a team led by the New Zealand Institute of Geological and Nuclear Sciences.
"We detected numerous chemical and particle plumes in the water column that extend at least 5 km from the centre of the volcano. This has been a great opportunity for us to obtain fundamental data on dynamic volcanic inputs to the ocean environment," says IGNS researcher Gary Massoth.
The RV Franklin returns to Darwin from the Coral Sea today (24 May, 2000), with scientists from Australia, New Zealand, Papua New Guinea, Solomon Islands and the USA on board.
Dr Ray Binns of CSIRO Exploration and Mining and his team recovered the huge submarine chimney from the bottom of the Bismarck Sea, north of Papua New Guinea. (See CSIRO media release 00/125, 9 May, 2000, http://www.csiro.au)
The world-record size "black smoker" is a one tonne, 2.7 metre high, mineral chimney prised from an active volcanic hotspring at a depth of 1700 metres.
"The chimney, swarming with remarkable microbes when collected, was formed by deep submarine volcanic activity. We expect it to prove rich in zinc, silver and gold," says Dr Binns.
The RAAF will be transporting this valuable and fragile specimen from Darwin to Sydney for further study later in the week.
More information: [email protected]
Digital film of Kavachi erupting available. Still photos available from http://www.csiro.au
The above story is based on materials provided by CSIRO Australia. Note: Materials may be edited for content and length.
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