Discovery

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Posts Tagged ‘geology’

Plate tectonics key to life on Earth?

Tectonic plates. Courtesy US Geological Survey

Tectonic plates. Courtesy US Geological Survey

Is our vital blue planet the last of its kind?  Or has it always been one of a kind?  From the perspective of post-modern geologists, planet Earth is like no other solar body yet discovered.

“I think when you live on the Earth, you take it for granted,” says Katie Cooper, who thoughtfully considers such esoteric questions for a living. As one of a relatively new group of geologists who use computer simulations to study the thermal and tectonic evolution of our planet, her viewpoint is decidedly celestial.

Cooper, assistant professor in the School of Earth and Environmental Sciences, studies the broad area of geodynamics—particularly the evolution of Earth as a planetary system. Specifically, she models how the three main layers of our planet—core, mantle, and crust (lithosphere)—interact and change over time.

“I look at the Earth as a giant heat engine which drives all of the geologic activity we see at the surface,” she says. “In the past, the core was hotter than it is today. The planet is slowly cooling and that affects everything on the lithosphere.”

That cooling takes place in large part through thermal convection. Like boiling water or the slow movement of oil blobs in a lava lamp, hot plastic rock from the Earth’s mantle is constantly rising toward the surface, where heat and energy are released in hot springs, earthquakes, or volcanic eruptions. At the same time, cooler rock is sinking toward the interior core.

This steady interplay leads to the phenomenon of plate tectonics where vast puzzle-like sections of Earth’s crust “float” on top of hot rock in the mantle—and imperceptibly migrate across the globe.

Earth stands alone

Although plate tectonics is often taken for granted as standard planetary modus operandi, it turns out that Earth is a world apart from other planets.

“Plate tectonics is unique to Earth as far as we know right now,” says Cooper. “The big question is if this is unique to our solar system? Our galaxy?  The universe?”

Not only unique, but possibly essential to life itself. Through its part in cooling the planet’s interior, plate tectonics allows Earth to maintain a magnetic field that shields our world from dangerous solar radiation and, in effect, creates a safe haven for life to flourish. Which presents Cooper with another question—did plate tectonics create optimal conditions for the initial occurrence of life?  No one knows for sure.

Plate tectonics—the next generation

For the first half of the twentieth century, geologists suspected that Earth’s continents had once formed a single land mass before breaking up and drifting aimlessly apart. The continental drift hypothesis was backed up by fossil evidence but no one could explain the actual physical processes driving it.

That changed in 1963, however, when Princeton professor, Harry Hess, used WWII submarine-hunting technology to discover unusual magnetic polarity in the ocean floor. It was concluded that hot rock from the mantle was rising up through the lithosphere and pushing the sea floor—and the continents on either side—apart.

This finding provided the mechanism to explain the purposeful movement of Earth’s plates and led to the development of the first theory of plate tectonics.

Today Cooper is among a new generation of geologists who study what could be called “post” plate tectonics. Taking the field up a notch, she investigates similar processes on other planets and asks why Earth has plate tectonics in the first place.

“Is it the preferred mode of operation?” she asks. “Does it help the planet lose heat most efficiently? Is it a coincidence?”

Using a computer cluster of 600 processors working together as a single unit, Cooper attempts to unlock these mysteries by crunching enormous calculations that often run days or weeks to generate results.

Doing these “paper and pencil calculations” as she refers to them, Cooper builds computer models of planets and applies basic laws of physics to see if the theories are applicable.

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More News of Life on Mars and Saturn’s Titan

For several years now, WSU astrobiologist Dirk Schulze-Makuch has been building a case for extraterrestrial life. Just this spring, he and several colleagues reported finding microbial life in an incredibly inhospitable lake of asphalt in the Caribbean, suggesting life might similarly be found in the liquid hydrocarbon environments of Saturn’s moon, Titan.

Now comes word that ancient Mars seems to have had a wet, non-acidic environment favorable to life. Researchers led by NASA’s Richard Morris and writing in the journal Science say the evidence lies in an outcrop of rock with high amounts of carbonate, which forms in wet conditions and dissolves in acid.

Carbonate-Containing Martian Rocks (color added)/Image courtesy of NASA, JPL-Caltech, and Cornell University

The finding, says Schulze-Makuch, “supports the notion of a warmer and wetter early Mars with substantial amounts of liquid water on its surface, probably in the form of oceans. Thus, early Mars was certainly a habitable planet and the origin of single-cellular life on Mars or transfer of that type of life from Earth to Mars or vice versa is certainly plausible.”

No sooner does Schulze-Makuch say this when we read of the Cassini spacecraft finding no sign of acetylene on Titan. A separate study found evidence that hydrogen is disappearing near the moon’s surface. The discoveries support a theory that Titanic microbes could survive by breathing hydrogen gas and eating acetylene, producing methane as a result.

Schulze-Makuch calls the discoveries “extremely intriguing.”

“A biological explanation would be quite plausible as hydrogen is the most basic ingredient for metabolism on Earth and acetylene is an energy-rich molecule that could be harvested as part of a methanogenic metabolism on Titan,” he says.

In fact, he predicted as much in 2005, writing with David Grinspoon in the journal Astrobiology.

“Obviously, inorganic explanations have to be eliminated as a possibility before we conclude that biology is the cause,” he says. “However, an inorganic explanation is difficult to invoke since a strong catalyst would be needed to remove the hydrogen and acetylene falling from Titan’s atmosphere under the very cold surface temperatures on Titan. Indeed, what is observed is exactly what we would expect if life on Titan is present that uses hydrogen and acetylene in its metabolic pathway and produces methane as a result.”

Very cool video of how the Spirit Mars Rover operates on rock can be seen here. You can also read a lot more about Schulze-Makuch’s thinking on extraterrestrial life in his recent and eminently readable book, We Are Not Alone.

Happy Anniversary, Mount St. Helens

Thirty years ago today, Mount St. Helens blew in one of the great natural spectacles of our time. The anniversary has launched several hundred retrospectives, many of which are highlighting work by Washington State University scientists.

In a piece for Voice of America news, Tom Banse visits with botanist John Bishop, who has spent decades studying the transition from sterile blast zone to habitat-rich ecosystem.

“What we’ve realized as we’ve spent a lot of time here and we’ve quantified the plants and the animals is that we actually have extraordinary levels of diversity here, of biological diversity,” he says.

Early morning sun on Mount St. Helens/Robert Hubner photo

In a Vancouver Columbian piece about preserving the mountain, Bishop encourages people to visit.

“There ought to be more people hiking out there, not less,” the newpaper quotes him as saying. “I think people ought to see the place. It’s wonderful. The recovery process is amazing, the vegetation is quite remarkable. It’s a very interesting place to visit.”

In a separate Columbian piece, reporter Erik Robinson explains how the blast created landscape patterns around the Toutle River similar to other, unexplained forms elsewhere.

Says John Wolff, WSU volcanologist and geochemist: “Almost as soon as that landslide had settled down, people said, ‘Whoa, this looks exactly like the corridor by Mount Shasta.’”

The coverage has a powerful alumni angle as well. The Daily News of Longview recounts how Trixie Anders, a WSU geology masters student, was riding up the mountain with Barry Johnston, her husband of the time, when at 8:32 a.m., “the event of a lifetime burst into our lives.” Turning around, the two outraced the plume of ash back down the mountain, barely.

For more on John Bishop’s work, see the Washington State Magazine piece, “Mount St. Helens: The perfect laboratory.”

The Northwest: One Happening Hotbed of Planetary Change

As metaphors go, the tree-shaped air freshener of the 1984 movie “Repo Men” is a standard for describing something that is ubiquitous, as in, “Find one in every car. You’ll see.” 

Columnar basalts outside Washtucna, Wash. WSU photo by Robert Hubner

Columnar basalts outside Washtucna, Wash. WSU photo by Robert Hubner

Which fairly describes the basalts of the Columbia Plateau that stretch from Idaho to Portland, often in massive brown columns hundreds of feet high and, as it turns out, thousands of feet deep.  Find one outside every car driving across S.R. 26 or down the Columbia Gorge. You’ll see. 

It turns out that rock originally burst on to the scene with enough volume, heat, gas and regularity to change the earth’s climate and knock off critters. Similar events have been found in Siberia, India and the eastern Americas. These basalt flows are the youngest in geologic time, the newest in terms of research, and the most local. 

To crib from my own news release: 

New research suggests the volcanic birth of the Northwest’s Columbia Plateau happened much more quickly than previously thought and with an intensity that may have changed the earth’s climate and caused some plants and animals to go extinct. 

“What you’re looking at are lava flows that repeat fairly quickly,” said Steve Reidel, research professor of geology at Washington State University Tri-Cities. “Not decades or centuries, but months or years.” 

Reidel is a co-author of a paper in the recent issue of the journal “Lithos” refining the time frame of the Grande Ronde lava flows, which produced enough molten basalt to sink the earth’s crust and created the vast Columbia River Plateau of Washington, Oregon and Idaho. 

Just one of the 100 or so lava flows would have blanketed much of Washington State in 10,000 cubic kilometers of lava—10,000 times the volume of ash produced by the 1980 eruption of Mount St. Helens. 

The flows moved at walking speed, enough time for the horses and other animals of the region to get out of their path. But a single flow could reach as far as Portland, be more than 2,000 degrees Fahrenheit and take half a century to cool. In the process, it would have generated monsoons across the Northwest and emitted enough heat and sulfur to alter the earth’s climate, said Reidel. 

Read more here. 

Reidel, by the way, is author of “Big Black Boring Rock: Essays on Northwest Geology” (Battelle Press). Is that a great title or what?