Geoscientists meet to discuss cordilleran geology

Geoscientists are gathering for the 105th Annual Meeting of the Cordilleran Section of the Geological Society of America, being held 7-9 May 2009 in Kelowna, British Columbia, Canada. The Earth and Environmental Sciences Program at the University of British Columbia-Okanagan is hosting the meeting.

The technical program, presented by academic and industry scientists, and graduate and undergraduate students, will highlight cutting-edge scientific research in themed and general discipline sessions.

TECHNICAL SESSION HIGHLIGHTS


Other Themed Sessions include:

  • Paleozoic Paleogeography of Cordilleran Terranes
  • Geoscience Framework for Metallogeny in the Southern Cordillera
  • Pulling Apart the Cordilleran Orogen: Tectonic and Magmatic Processes Revealed within Extensional Terranes

View the complete technical program at http://gsa.confex.com/gsa/2009CD/finalprogram/.

FIELD TRIP HIGHLIGHTS


Best known for its lakes, ski hills, and vineyards, Kelowna is also in the middle of a geologic paradise. Field trips will include destinations to regions exhibiting extension, compressional, and volcanic processes. The accessible geology includes Proterozoic basement complexes, Eocene and Miocene volcanic-plutonic complexes, and Quaternary glacial and deglacial landforms and sediments. Kelowna is also within a few hours’ drive of the Burgess Shales area.

MEETING, REGISTRATION, AND HOUSING INFORMATION


Complete meeting information is available at http://www.geosociety.org/sectdiv/cord/09mtg/index.htm

Information on registration is available at http://www.geosociety.org/sectdiv/cord/09mtg/registration.htm. Information on lodging is available at http://www.geosociety.org/sectdiv/cord/09mtg/lodging.htm.

MEDIA REGISTRATION INFORMATION


Eligibility for media registration is as follows:

  • Working press representing bona fide, recognized news media with a press card, letter or business card from the publication.
  • Freelance science writers, presenting a current membership card from NASW, ISWA, regional affiliates of NASW, ISWA, CSWA, ACS, ABSW, EUSJA, or evidence of work pertaining to science published in 2008 or 2009.
  • PIOs of scientific societies, educational institutions, and government agencies.

Complimentary meeting registration covers attendance at all technical sessions and access to the exhibit hall. Journalists and PIOs must pay regular fees for paid luncheons and any short courses or field trips in which they participate. Representatives of the business side of news media, publishing houses, and for-profit corporations must register at the main registration desk and pay the appropriate fees.

Marine scientists return from expedition to erupting undersea volcano

Scientists who have just returned from an expedition to an erupting undersea volcano near the Island of Guam report that the volcano appears to be continuously active, has grown considerably in size during the past three years, and its activity supports a unique biological community thriving despite the eruptions.

An international science team on the expedition, funded by the National Science Foundation (NSF), captured dramatic new information about the eruptive activity of NW Rota-1.

“This research allows us, for the first time, to study undersea volcanoes in detail and close up,” said Barbara Ransom, program director in NSF’s Division of Ocean Sciences, which funded the research. “NW Rota-1 remains the only place on Earth where a deep submarine volcano has ever been directly observed while erupting.”

Scientists first observed eruptions at NW Rota-1 in 2004 and again in 2006, said Bill Chadwick, an Oregon State University (OSU) volcanologist and chief investigator on the expedition. This time, however, they discovered that the volcano had built a new cone 40 meters high and 300 meters wide.

“That’s as tall as a 12-story building and as wide as a full city block,” Chadwick said. “As the cone has grown, we’ve seen a significant increase in the population of animals that lives atop the volcano. We’re trying to determine if there is a direct connection between the increase in the volcanic activity and that population increase.”

Animals in this unusual ecosystem include shrimp, crab, limpets and barnacles, some of which are new species.

“They’re specially adapted to their environment,” said Chadwick, “and are thriving in harsh chemical conditions that would be toxic to normal marine life.

“Life here is actually nourished by the erupting volcano.”

Verena Tunnicliffe, a biologist from the University of Victoria, said that most of the animals are dependent on diffuse hydrothermal venting that provides basic food in the form of bacterial filaments coating the rocks.

“It appears that since 2006 the diffuse venting has spread and, with it, the vent animals,” Tunnicliffe said. “There is now a very large biomass of shrimp on the volcano, and two species are able to cope with the volcanic conditions.”

The shrimp reveal intriguing adaptations to volcano living.

“The ‘Loihi’ shrimp has adapted to grazing the bacterial filaments with tiny claws like garden shears,” said Tunnicliffe. “The second shrimp is a new species–they also graze as juveniles, but as they grow to adult stage, their front claws enlarge and they become predators.”

The Loihi shrimp was previously known only from a small active volcano near Hawaii–a long distance away. It survives on the fast-growing bacteria and tries to avoid the hazards of the volcanic eruptions. Clouds of these shrimp were seen fleeing volcanic bursts.

The other species attacks the Loihi shrimp and preys on marine life that wanders too close to the volcanic plumes and dies. “We saw dying fish, squid, etc., raining down onto the seamount, where they were jumped on by the volcano shrimp–a lovely adaptation to exploiting the noxious effects of the volcano,” Tunnicliffe said.

The new studies are important because NW Rota-1 provides a one-of-a-kind natural laboratory for the investigation of undersea volcanic activity and its relation to chemical-based ecosystems at hydrothermal vents, where life on Earth may have originated.

“It is unusual for a volcano to be continuously active, even on land,” Chadwick pointed out.

“This presents us with a fantastic opportunity to learn about processes we’ve never been able to directly observe before,” he said. “When volcanoes erupt in shallow water they can be extremely hazardous, creating huge explosions and even tsunamis. But here, we can safely observe an eruption in the deep ocean and learn valuable lessons about how lot lava and seawater interact.”

Chadwick said that volcanic plumes behave completely differently underwater than on land, where the eruption cloud is filled with steam and ash, and other gases are invisible.

“In the ocean, any steam immediately condenses and disappears and what is visible are clear bubbles of carbon dioxide and a dense cloud made of tiny droplets of molten sulfur, formed when sulfur dioxide mixes with seawater,” Chadwick said. “These volcanic gases make the eruption cloud extremely acidic–worse than stomach acid–which is another challenge for biological communities living nearby.”

Ocean acidification is a serious concern because of human-induced carbon dioxide accumulating in the atmosphere. “Submarine volcanoes are places where we can study how animals have adapted to very acidic conditions,” Chadwick said.

During the April 2009 expedition, aboard the University of Washington’s R/V Thompson, the scientists made dives with Jason, a remotely operated vehicle (ROV) operated by the Woods Hole Oceanographic Institution.

Chadwick said that “it was amazing how close Jason can get to the eruptive vent because the pressure at a depth of 520 meters [about 1,700 feet] in the ocean keeps the energy released from the volcano from becoming too explosive.” Some of the most intriguing observations came when the volcano slowly pushed lava up and out of the erupting vent.

“As this was happening, the ground in front of us shuddered and quaked, and huge blocks were bulldozed out of the way to make room for new lava emerging from the vent,” Chadwick said.

Part of the evidence that the volcano is in a constant state of eruption comes from an underwater microphone–or hydrophone–that was deployed a year ago at NW Rota-1 by OSU geologist Bob Dziak.

The hydrophone “listened” for the sounds of volcanic activity. The data it recorded clearly show that the volcano was active the entire year before the latest expedition. Another hydrophone and other instruments will monitor the volcano in the coming year.

The international team included scientists from OSU, the University of Washington, University of Victoria, University of Oregon, NOAA’s Pacific Marine Environmental Laboratory, New Zealand and Japan.

Sea-floor sediments illuminate 53 million years of climate history

Two back-to-back ocean drilling expeditions will study sea-floor sediments and climate change. -  Consortium for Ocean Leadership/IODP
Two back-to-back ocean drilling expeditions will study sea-floor sediments and climate change. – Consortium for Ocean Leadership/IODP

The Integrated Ocean Drilling Program (IODP) drillship JOIDES Resolution is returning to port in Honolulu this week after a two-month voyage to chart detailed climate history in the equatorial Pacific Ocean. The expedition was the first of two back-to-back voyages of a scientific project called Pacific Equatorial Age Transect (PEAT). It was the first international scientific drilling expedition after the JOIDES Resolution underwent a multi-year transformation into a 21st-century floating science laboratory.

The PEAT expeditions are recovering a series of continuous historical records in sediments at a number of different geographic locations beneath the equatorial Pacific Ocean. The first research effort, called Expedition 320, took place March 5 through May 4, 2009; Expedition 321 will take place from May 5 through July 5, 2009.

Co-chief scientists of Expedition 320 were Heiko Palike of the University of Southampton, U.K., and Hiroshi Nishi of Hokkaido University in Japan. On Expedition 320, scientists obtained records from the present back in time to the warmest sustained “greenhouse” period on Earth, which took place around 53 million years ago.

Shipboard studies have revealed that changes in ocean acidification linked to climate change have a large and global impact on marine organisms.

“The sediments collected during this expedition offer an unprecedented window to the evolution of the tropical Pacific, one of the largest and most climatically important ocean regions on Earth,” said Julie Morris, director of NSF’s Division of Ocean Sciences.

“In focusing on a time period that includes some of the best analogs for abrupt climate change, extreme climate events, ocean acidification, and ‘greenhouse’ worlds, the results will give us insights into the potential impacts of future climate change.”

Environmental changes are recorded by shells of tiny microfossils that make up the deep-sea sediments.

“We can use the microfossils and layers of this sediment ‘archive’ as a yardstick for measuring geologic time,” said Expedition 320 co-chief scientist Hiroshi Nishi.

“This will allow us to determine the rates of environmental change, such as the rapid first expansion of large ice-sheets in the Antarctic 33.8 million years ago. This polar process had a profound impact on phytoplankton even at the equator.

“We managed to retrieve several records of this important climate transition.”

Expedition 320 co-chief scientist Heiko Pälike said that “it’s truly remarkable to see 53 million years of Earth’s history pulled up onto the drillship’s deck, then pass through our hands, and move past our eyes. We saw first-hand the effects of Earth’s climate machine in action.”

For the upcoming Expedition 321, co-chief scientists will be Mitch Lyle of Texas A&M University in the U.S., and Isabella Raffi of the Universita “G. D’Annunzio” Campus Universitario in Italy.

Comparing Mars to Earth: Catastrophe and history

GSA Special Paper 453: Preservation of Random Megascale Events on Mars and Earth: Influence on Geologic History, edited by Mary G. Chapman and Laszlo P. Keszthelyi. -  Geological Society of America
GSA Special Paper 453: Preservation of Random Megascale Events on Mars and Earth: Influence on Geologic History, edited by Mary G. Chapman and Laszlo P. Keszthelyi. – Geological Society of America

This GSA Special Paper focuses on the catastrophic events that have influenced both Mars and Earth and is part of the ongoing search for the correct balance between catastrophic and uniformitarian processes. The book aims to “expand the geoscience horizons” of a wide range of readers by examining evidence for various geologic catastrophes on both Earth and Mars, their preservation on Earth as compared to Mars, and how these events may have influenced Earth’s evolution.

Catastrophic events discussed in this volume include impact cratering, megafloods, megascale eruptions, sub-ice volcanism on Earth, and natural disasters and human behavior.

Volume editors Mary G. Chapman and Lazlo P. Keszthelyi of the U.S. Geological Survey’s astrogeology team want to know why such large, catastrophic, and unusual events are readily apparent on the surface of Mars but are relatively poorly recorded on Earth. They ask whether the differences are solely the result of the poor preservation on Earth due to gradualistic processes such as tectonics and erosion, or whether they are due to inherent differences in the gravity, atmosphere, climate, and materials of the two planets.

The six chapters in this volume also address the questions, “What is the relative importance of non-uniform, catastrophic, and unusual processes as compared to gradualistic, uniformitarian processes in shaping the geomorphic, climatic, and biotic history of the Earth? What can we learn about these processes on Mars that we can extend to our knowledge of the Earth?”

Southern glaciers grow out of step with North

Scientist Joerg Schaefer rests on a glacial moraine in New Zealand's Southern Alps. -  Joerg Schaefer
Scientist Joerg Schaefer rests on a glacial moraine in New Zealand’s Southern Alps. – Joerg Schaefer

The vast majority of the world’s glaciers are retreating as the planet gets warmer. But a few, including ones south of the equator, in South America and New Zealand, are inching forward.

A new study in the journal Science puts this enigma in perspective; for the last 7,000 years New Zealand’s largest glaciers have often moved out of step with glaciers in the northern hemisphere, pointing to strong regional variations in climate.

Conventional wisdom holds that climate during the era of human civilization has been relatively stable, but the new study is the latest to challenge this view, by showing that New Zealand’s glaciers have gone through rapid periods of growth and decline during the current interglacial period known as the Holocene.

“New Zealand’s mountain glaciers have fluctuated frequently over the last 7,000 years and glacial advances have become slightly smaller through time,” said lead author Joerg Schaefer, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory. “This pattern differs in important ways from the northern hemisphere glaciers. The door is open now towards a global map of Holocene glacier fluctuations and how climate variations during this period impacted human civilizations.”

Glaciers are extremely sensitive to changes in temperature and snowfall, which makes them well suited for studying past climate. This archive has been largely untapped, however, because of the difficulty in assigning precise ages to glacier fluctuations.

One way to measure glacial fluxes is by studying the moraines, or rock deposits that glaciers often leave behind at their maximum points of advance. However, until now the methods of dating such moraines, including radiocarbon dating of organic matter, could be off by hundreds of years. By refining the analysis of a method called cosmogenic dating, Schaefer and his colleagues were able for the first time to assign precise ages to young Holocene moraines. They did this by measuring minute levels of the chemical isotope beryllium 10 in the rocks, which is produced when cosmic rays strike rock surfaces, and builds up over time. The researchers were thus able to pinpoint exactly when glaciers in New Zealand’s Southern Alps began to recede, exposing the rocks to the cosmic rays.

From the results, they constructed a glacial timeline for the past 7,000 years and compared it against historic records from the Swiss Alps and other places north of the equator.

They found that the glaciers around Mount Cook, New Zealand’s highest peak, reached their largest extent in the past 7,000 years about 6,500 years ago, when the Swiss Alps and Scandinavia were relatively warm. That’s about 6,000 years before northern glaciers hit their Holocene peak during the Little Ice Age, between 1300 and 1860 AD.

That finding was a surprise to some scientists who assumed that the northern cold phase happened globally. The record in New Zealand shows other disparities that point to regional climate variations in both hemispheres, including glacial peaks during classic northern warm intervals such as the Medieval Warm Period and the Roman Age Optimum.

The new chemical and analytical protocols developed in Schaefer’s cosmogenic dating lab is expected to allow scientists to accurately date glacier fluctuations throughout the Holocene, rounding out the climate picture on the continents.

“With this measure we can go to almost any mountain range on earth and date the moraines in front of the glaciers and produce a similar chronology,” said coauthor George Denton, a glaciologist who is a senior professor at the University of Maine and an adjunct scientist at Lamont-Doherty.

Overall, glaciers around the world have been declining since about 1860, with the exception of a brief advance in Switzerland in the 1980s, New Zealand in the late 1970s through today, and a few other places. Changes in wind and sea surface temperatures are thought to be causing these regional fluctuations. Currently in a wet phase, New Zealand is expected to swing back to a warmer, drier phase in the next few years, causing the glaciers to retreat once again.

“The application of this technique should allow for much more accurate
reconstructions of glacial advances worldwide,” says Paul Filmer, program director for the National Science Foundation (NSF)’s Division of Earth Sciences, which helped fund the study. “This would provide more constraints to allow us to make our climate models more accurate.”

Contrary to recent hypothesis, ‘chevrons’ are not evidence of megatsunamis

The black arrows indicate the orientation of chevrons along the southern coast of Madagascar, but the white arrows indicate what computer models say should have been the orientation if they were caused by the impact of a space body in the Indian Ocean. -  Robert Weiss
The black arrows indicate the orientation of chevrons along the southern coast of Madagascar, but the white arrows indicate what computer models say should have been the orientation if they were caused by the impact of a space body in the Indian Ocean. – Robert Weiss

A persistent school of thought in recent years has held that so-called “chevrons,” large U- or V-shaped formations found in some of the world’s coastal areas, are evidence of megatsunamis caused by asteroids or comets slamming into the ocean.

University of Washington geologist and tsunami expert Jody Bourgeois has a simple response: Nonsense.

The term “chevron” was introduced to describe large dunes shaped something like the stripes you might see on a soldier’s uniform that are hundreds of meters to a kilometer in size and were originally found in Egypt and the Bahamas.

But the discovery of similar forms in Australia and Madagascar led some scientists to theorize that they were, in fact, deposits left by huge tsunami waves, perhaps 10 times larger than the devastating Indian Ocean tsunami of December 2005.

Such huge waves, they suggest, would result from the giant splash of an asteroid or comet hitting the ocean. They also suggest one such impact occurred 4,800 to 5,000 years ago, and that chevrons in Australia and Madagascar point to its location in the Indian Ocean.

But Bourgeois said the theory just doesn’t hold water.

For example, she said, there are numerous chevrons on Madagascar, but many are parallel to the coastline. Models created by Bourgeois’ colleague Robert Weiss show that if they were created by tsunamis they should point in the direction the waves were travelling, mostly perpendicular to the shore.

“And if it really was from an impact, you should find evidence on the coast of Africa too, since it is so near,” said Bourgeois, a UW professor of Earth and space sciences who has studied earthquakes and tsunamis in various parts of the world.

In a paper in the May issue of Geology, Bourgeois and Weiss, an assistant professor of geology at Texas A&M University, conclude that “the extraordinary claim of ‘chevron’ genesis by megatsunamis cannot withstand simple but rigorous testing.”

The scientists used an online program called Google Earth, made up of satellite images of the Earth’s surface, to get close-up looks at chevrons in different locations. Chevrons often are found in coastal areas, but they also are common in semiarid areas inland.

“There are the same forms in the Palouse in eastern Washington state, and those are clearly not from a tsunami,” Bourgeois said.

For the research, Weiss created a computer model that generated actual conditions that would occur during a tsunami. The scientists then used the model to examine what would happen if an asteroid or comet hit in the area theorized by the megatsunami proponents. The model showed the wave approach would be at a 90-degree orientation to the chevron deposits. But if the megatsunami interpretation is correct, the chevrons should be parallel to wave approach.

“That’s just not the case here. The model shows such a tsunami could not have created these chevrons, unless you have some unimaginable process at work,” Bourgeois said.

Asteroids and comets bombarded Earth in the distant past, at times with devastating consequences, such as the impact 65 million years ago that is believed to have sent dinosaurs to their extinction. There have been large impacts since but probably nothing comparable.

Proponents of the megatsunami theory have suggested that the dunes could not have been created by other forces, but Bourgeois believes their interpretation is faulty.

“They claim these are not consistent with the patterns of prevailing winds, but in fact they are consistent with the wind. They are not consistent with what a tsunami would do,” she said.

The discovery of marine fossils in some chevron formations seems to support the idea that a wave created the deposit, but Bourgeois discounts that evidence also.

“Marine fossils can get into non-marine deposits. It’s not uncommon. You only have to change sea level a little bit or have them wash up on a beach in a storm,” she said. “And some marine organisms can be carried by the wind. I am convinced these are largely wind-blown deposits.”

She noted that similar deposits have been seen on the Kamchatka Peninsula on Russia’s east coast, where she has conducted research for more than a decade.

“Those are made of volcanic ash, and they are not near the coast at all, yet they look very similar to these coastal chevrons,” Bourgeois said.