Monday, February 16, 2009

Hawaiian volcanoes are way older than thought, and there's life down 1.6 miles

Hawaiian volcanoes are dramatically more complex—and far older—than scientists have been teaching—and there are traces of life more than a mile deep in the rock.

Those are just a few of the remarkable findings of a truly quirky idea: Let's drill miles down into the lava on the Big Island and see what we find.

The Hawaii Scientific Drilling Project was launched in theory in the 1980s, with drilling started in the 1990s, a joint research project of the University of Hawai'i, University of California, Berkeley, and California Institute of Technology. It involves a core of rock collected by drilling nearly three miles into the rock near Hilo.

The goal was to collect a continuous sample of of a million years of volcanic activity, reaching rock dating from a time when Mauna Kea was younger than the nascent volcano Lo'ihi is now.

The core was started in an abandoned quarry near Hilo Airport. It was selected because it was midway between active rift zones of Mauna Kea and Mauna Loa, so there would be less likelihood of hitting molten rock.

The first pilot hole was put down in 1993, and a 3-kilometer deep core was taken in 1999. The drilling went on for several years, and the coring stopped when the site reached 11,500 feet—more than two miles down.

“There are problems with age-dating Hawaiian lavas,” but research suggests the lavas at the bottom of the hole are 700,000 years old said geochemist Donald M. Thomas, director of Center for the Study of Active Volcanoes at the University of Hawai'i's Hawai‘i Institute of Geophysics and Planetology, a part of the School of Ocean and Earth Science and Technology.

The coring project has spawned dozens of scientific papers. In one of the most recent, published yesterday (Feb. 15, 2009), researchers from Germany, Japan and the United States reported that they could calculate the rate at which volcanic glass cooled—and could tell, for instance, whether lava was erupted above or below the surface of the ocean.

In a 2006 meeting, researchers reported on some of the many findings of the project. Thomas, with lead author Donald DePaolo of the University of California at Berkeley and Edward Stolper of the California Institute of Technology, said the coring project produced all kinds of results.

Researchers found that Mauna Kea lavas were twice as old as surface studies suggested. The rough estimate until now has been that the first volcano to be part of the Big Island started up off the ocean floor a million years ago (that might have been the volcano that formed the Kohala Mountains. Based on the coring project, the new Big Island age estimate is as much as 2.5 million years.

“The accepted model is that it takes about a half a million years to get from the ocean floor to the height of Mauna Kea.,” but the new work suggests it could take two to three times that, Thomas said.

Even a mile deep under the volcano, where you'd expect it to be hot, it's pretty cool—only about 54 degrees—because cold ocean water circulates through the rock.

There are both freshwater and saltwater aquifers existing under pressure as much as a mile and a half down, “which was unexpected and has implications for water resources,” the trio reported. They bored down through Mauna Loa lavas, passing through a fresh water aquifer as they went, then hit salt water, and later, deep in Mauna Kea lavas, they hit another pressurized aquifer of fresh water.

“The hydrology of the island is much more complex than we anticipated...Mauna Kea is discharging fresh water 1000 feet below sea level,” Thomas said.

And there are signs of life, albeit microbiotic life, as much as 1.6 miles down. Researchers found evidence of microscopic boring by rock-loving microbes inside rocks deep in the volcano. Reports on this are here.

Thomas said scientists have found DNA in the bottoms of some of the microborings, suggesting that there is still active life there, in rock hundreds of thousands of years old, and thousands of feet below the surface.

©2009 Jan TenBruggencate

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