New hydrothermal vents discovered as 'South Pacific Odyssey' research begins

09/23/04



R/V Kilo Moana, one of the research vessels used on the Lau expeditions.
Credit: Charlotte Goddard, Oregon State University

Full size image available here

A team of 27 U.S. marine scientists beginning an intensive program of exploration at the Lau Basin in the South Pacific has discovered a new cluster of hydrothermal vents along a volcanically active crack in the seafloor. About a mile and a half down, the basin could hold answers to questions about the origin of life on Earth, say the scientists, whose plans for their "South Pacific Odyssey" include an unprecedented number of research expeditions to this geologically unique "back-arc basin" during the next two years.

"This major undertaking will require the coordinated efforts of dozens of large research groups, numerous research expeditions, and the deployment of a wide array of specialized deep-sea research tools," said Penn State Professor of Biology Chuck Fisher, chair of the NSF-funded Ridge 2000 research initiative, which is behind this effort. "Because of the unusual properties of the ocean crust in the Lau Basin, we can expect to discover new species there--species that perhaps will hold new and unique secrets to share with us," Fisher said. "The microbes at sites like these--thriving in super-hot temperatures--likely have their own remarkable biochemical pathways and capabilities that we are only beginning to appreciate."

"The Lau Basin is a candy store of scientific problems, and this is the first time there's been a regional-scale perspective of hydrothermal activity in an entire back-arc basin," said Charlie Langmuir of Harvard University, a marine geologist who is the chief scientist of the current cruise and a veteran of over 20 deep-sea expeditions in the last two decades. "If we're successful, it will also be the first time that a systematic exploration and discovery of hydrothermal vents over hundreds of kilometers has been achieved."

Continuous updates about this series of expeditions and its discoveries are being posted on the web at www.southpacificodyssey.org, including reports by on-scene science writers and intriguing information about south Pacific life and culture.

MORE ABOUT THE LAU BASIN



Snails (Alviniconcha hessleri) found at Vai Lili vent site in the Lau Basin.
Credit: Daniel Desbruyeres, IFREMER (French Research Institute for Exploitation of the Sea

Full size image available here

The Lau Basin, a 390-kilometer stretch of the ocean basement about the length of Taiwan, has captured the interest of scientists since the late 1960s. Lined with active deep-sea volcanoes and hydrothermal vents--along with massive sulfide deposits enriched in gold and other minerals--it is home to gigantic snails and other strange animals that live in total darkness off of the hot, acidic vent water. Many scientists have dubbed the basin "the perfect geologic experiment," an ideal place to study the processes that connect Earth's deep interior to ocean ridge volcanoes and the biological communities they support in the complete absence of sunlight.

The Lau Basin is flanked by two underwater mountain ridges that sit roughly between Fiji in the west and the Kingdom of Tonga in the east; the ridges run south toward New Zealand. "We are fortunate to have the full support of the Kingdom of Tonga, as our research area is in its territorial waters," said Fisher. The Kingdom of Tonga is dubbed "the land where time begins" because of its location immediately west of the International Dateline. Tongans are the first in the world to greet the dawn of a new day.

"The Lau Basin was chosen by the U.S. research community as the best place in the world to study the links between the geology, chemistry, and biology of a back-arc spreading center and to understand the large-scale cycling of materials from the seafloor to the Earth's interior and back again," Fisher said.

The Lau Basin site is unique by virtue of its being a back-arc basin, where spreading splits the ocean floor apart very close to a volcanic arc. The way the geology works in a back-arc basin is different from the way it works in a mid-ocean spreading center. In back-arc basins, which are widespread in the western Pacific Ocean, a spreading center is located right next to a subduction zone (the Tonga Trench) where one plate of Earth's crust dips beneath another one. The Lau Basin opens up a "window" into the deep Earth below, revealing the process involved as plates recycle. The subducting plate also contributes many chemicals to the overlying volcanoes of the Lau Basin, creating ocean crust of unique composition.

MORE ABOUT THE 2-YEAR EXPLORATION OF THE LAU BASIN



Hydrothermal venting though sulfide chimneys in the Lau Basin.
Credit: Daniel Desbruyeres, IFREMER (French Research Institute for Exploitation of the Sea)

Full size image available here

The "South Pacific Odyssey" expedition of the Ridge 2000 program is a series of five cruises scheduled through June 2005 like the passing of a baton in a relay race: what scientists learn on the early cruises is essential for the success of subsequent cruises. The ambitious research goals include high-resolution mapping, sampling of deep-sea volcanism, photography of the ocean floor, ananlysis of water chemistry analysis, and up-close-and-personal observations of the microbes making a living in such a bizarre environment.

All told, about 100 scientists from nearly 20 science institutions are involved in the quest to unravel the mysteries of the Lau Basin. Lanmuir said the project is the most complex cruise that he has been involved with because of the large number of different programs that have to be coordinated and the large number of high-tech and low-tech instruments that will be deployed. The team will use tools ranging from the most sophisticated submersibles and sensors to basic rock grabbers. Also working on behalf of the research team will be the newest addition to the U.S. research fleet, a super-stable, twin-hull research vessel called the R/V Kilo Moana, a name that literally means "one who wants to learn more about the ocean" in Hawaiian. Home base for the R/V Kilo Moana is the University of Hawaii.

One of the primary goals of the scientific team is to identify a 'bull's eye' site, a localized site that will become their research focus for years to come. The bull's eye can be visualized as a series of expanding bands around a volcanically active region.

The National Science Foundation is funding the Lau Basin research in 2004 and 2005, Fisher said. As the Lau Basin also is being studied by such countries as Japan, Australia, and France, Fisher said he hopes more scientists will hop onboard and get into the Lau Basin action. "We are committed to following up with additional research expeditions in following years. Sharing the research costs internationally will enable us to better understand this complex system and will help us to achieve our goals sooner rather than later," he said.

Source: Eurekalert & others

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