New Zealand, American, and Japanese scientists have found new submarine hot springs northeast of New Zealand.
Using new equipment deployed from the research ship Tangaroa, they spent the past fortnight investigating 13 newly
mapped submarine volcanoes and six smaller cones for seabed thermal activity.
The survey area, within New Zealand's Exclusive Economic Zone, extended from Brothers Volcano, 400km northeast of White
Island, to Curtis and Macauley Islands at the southern end of the Kermadec group of islands - a distance of 500km.
The scientists returned to Wellington today with hot volcanic rocks from the seafloor and a range of marine animals and
organisms that thrive in scalding volcanic plumes that would be toxic, even fatal, to most life forms on the planet.
A large stretch of the area they surveyed showed no sign of volcanic or hydrothermal activity. But at the northern end
they found three of the undersea volcanoes venting hot fluids and gases.
The first was about 20km south of Curtis Island, the second adjacent to Macauley Island, and the third 16km northwest of
Macauley Island. The most vigorous hydrothermal venting was recorded at the two volcanoes near Macauley Island.
" We found large plumes coming from both volcano summits as well as from their flanks," said project leader and marine
geologist Cornel de Ronde, of the Institute of Geological and Nuclear Sciences Limited (GNS).
The plumes are typically very rich in iron, manganese and copper along with lesser concentrations of zinc, lead and
gold. Dissolved metallic compounds in the plumes precipitate out and settle on the seabed forming large mineral
deposits.
The scientists recovered rocks from the two volcanoes and found deposits of metallic minerals at both sites.
" We broke open steaming hot rocks from these sites on the deck of the Tangaroa. They were measured at 57 degrees
Celsius," Dr de Ronde said.
" However, overall we found less hydrothermal and volcanic activity in the northern section of the Kermac Arc than in
the 400km section closer to New Zealand that we surveyed in 1999.
" It's as if parts of the Arc are switched on and other parts are switched off. It would seem that magma and heat from
the boundary between the Australian and Pacific plates reaches the Earth's crust in some places and not in others."
With this voyage and the initial one in 1999, the scientists have surveyed about 800km of the Kermadec Arc and found 11
active vent sites - all within New Zealand's EEZ. Most of the vent sites feature metallic mineral deposits that are
actively forming.
They also recovered a number of vent-related animals from the two sites near Macauley Island. They included two species
of mussel, clams, crabs, flat fish, eels, and other shellfish.
" Microbilogists on the ship recovered microbes from seawater in the black smoker plumes. They were able to grow them in
lab conditions up to 70 degress Celsius showing that they are thermophiles and almost certainly derived from the
hydrothermal vents themselves."
The scientists also re-surveyed a number of the active vent sites they found in 1999. At Healy volcano, about 200km
northeast of White Island, they found two new "very active" vents.
" The voyage confirms that the Kermadec Arc is a particularly important feature on the Earth's surface with its
hydrothermal vents expelling large volumes of hydrothermal elements into the ocean.
" However, these latest findings suggest the occurrence of venting along this Arc is more complex than previously
thought."
Dr de Ronde said the 2000km-long chain of undersea volcanoes between New Zealand and Tonga had been only partly mapped
and was not well understood.
The voyage was a collaborative project involving GNS, the National Oceanic and Atmospheric Administration (NOAA), the
University of Kyushu, HortResearch, and NIWA. It was led by GNS.
ENDS