Experts Hope Rocks Unravel Earth’s Secrets
COLLEGE STATION, Texas — The small gray and black rocks stored in 3-foot-long clear plastic tubes at a Texas A&M University lab could be mistaken for the leftovers after a kitchen countertop installation.
But the surprisingly heavy pebbles are much more significant. They’re part of the only intact section of oceanic crust ever recovered, pulled from beneath the Pacific Ocean by geologists drilling more than a mile into the sea floor.
Scientists hope this latest effort in the generations-old attempt to get closer to the center of the planet – achieved as part of the world’s biggest earth science program – can help unlock some of earth’s longest-held secrets.
“I would say this is just like a voyage of discovery to the planet Mars, except this is inner space rather than outer space,” said Neil Banerjee, staff scientist for the Integrated Ocean Drilling Program at Texas A&M. “We’re learning about the fundamental dynamics of how our planet works.”
Banerjee said the oceanic work adds to the knowledge about climate, earthquakes and of how mountains are built.
The pebbles, known as gabbros, were found in the crust below the Pacific Ocean about 400 miles west of Costa Rica. They were once red-hot magma boiling from deep within the earth that formed the sea floor when it contacted water 15 million years ago.
“Consider 60 percent of the earth surface is made in this fashion,” said Jeff Fox, director of the Integrated Ocean Drilling Program. “What’s exciting to geologists is, although it’s frozen now, it’ll provide a record of this fundamental planetary process which is responsible for paving the floors of the oceans.”
The recovery is the culmination of a project that began in 2002, when an international team of scientists aboard a ship designed for the oil industry began drilling in 3,600 feet of water.
They went back in July 2005, deepened their hole, and returned again in November, wearing out 25 paint bucket-sized drill bits to get about a mile into the sea floor. That was when, for the first time, they cracked the magma chamber.
“Ten years ago, a lot of people would have said we couldn’t accomplish this,” Banerjee said. “They would have thought the technical challenges were overwhelming.”
Hundreds of feet of core from the hole was recovered and will be analyzed, but only 9 meters – less than 30 feet – is gabbros. Among the rocks is one piece marked by a distinct white stripe showing a boundary where liquids cooled at different times.
“We went from rocks cooled relatively quickly, days or weeks, to rocks that took months or years,” Banerjee said. “The piece is the holy grail. We just got incredibly lucky that we have a core that preserves that particular boundary. It’s the first time that boundary has even been intersected.”
Fox said the pebbles are priceless.
“It’s worth a lot of money only in the story it will tell after a lot of scientists squeeze out information,” he said.
More than a century ago, the thought of reaching deep inside the earth was the stuff of fantasy.
Jules Verne’s famous science fiction novel, “Journey to the Center of the Earth,” was the tale of a German scientist accompanied by his nephew and a guide who hike into a volcano to investigate the earth’s interior secrets.
In the late 1950s, an ambitious effort dubbed Project Mohole was an attempt to go inward at the same time the nation’s fledgling space program was moving outward. The goal was to retrieve a sample of the earth’s mantle, the level beneath the earth’s crust and above the core. After eight years, with only one of three phases of the project complete, Congress cut off the money. Mohole was a dry hole.
“We probably know more about the surface of Mars now than we know about the interior of our planet,” Banerjee said. “That’s why it’s important for people to understand that this may be expensive, but if you compare to how much space research is, it’s providing us with really fundamental information that’s helpful for everyday lives. It lets us know how the planet works.”
Unlike Verne’s scientists, whose volcano gateway in 1864 was in Iceland, the gabbros recovery team headed for the tropics and the ocean with scientists representing 20 countries.
“What drives that fundamentally is the record of the earth’s history is written in greater clarity in the sediments of rocks on the sea floor than anywhere else,” Fox said.
Doug Wilson, a geophysicist from the University of California at Santa Barbara and a co-chief scientist on an earlier expedition, studied the magnetic properties of the ocean crust to help determine a suitable drilling site.
“Finding the right place to drill was probably key to our success,” Wilson said of the 15 million-year-old region of the Pacific Ocean floor.
Researchers have determined areas of the ocean are the most attractive drilling sites because the tectonic plates that make up the crust are far narrower than on land.
“It’s also cheaper,” noted Banerjee.
Still, the ship costs A&M about $45 million a year, or some $130,000 a day, making the program the largest earth science program in the world both in size of international partners and annual budget.
The program is backed by two lead agencies, the U.S. National Science Foundation and Japan’s Ministry of Education, Culture, Sports, Science and Technology, plus a consortium of 17 European countries and China.
Scientists already are making proposals to return for deeper drilling, perhaps as early as 2009.
In the meantime, as staff scientist, Banerjee has the difficult task of helping determine who among the researchers gets a piece of the rocks.
“It takes a careful arbitrator,” Fox said, smiling at his colleague. “As you can imagine, this is like a dead water buffalo on the Serengeti surrounded by jackals.
“Scientists who have spent their career thinking about this in one fashion or the other, they all want their science, their piece.”