Danish research center to explore mysteries of Earth’s interior

The DanSeis Centre at the University of Copenhagen has just received a grant of more than ?3 million from the Danish Ministry of Science, Innovation and Higher Education to investigate and tackle one of geoscience’s great mysteries: do mantle plumes, hypothetically buoyant regions of heated mantle material rising towards the earth’s surface, actually exist?

“It is believed that there are roughly 30 mantle plumes scattered about the planet. From them, heated mantle material rises from the Earth’s liquid core, into the lithosphere and towards the crust. Some of the most impressive plumes are presumed to be located beneath Iceland, Hawaii and Yellowstone National Park in the US state of Wyoming – all areas with significant volcanic activity and hot spots. Until now, the sciences have been unable to prove their existence. With the DanSeis Centre and its research staff, we will be equipped to provide new data and settle the question,” says Professor Hans Thybo of the University of Copenhagen’s Department of Geography and Geology (ICG). The Department is behind the DanSeis national instrument centre.

Hundreds of kilometers within the Earth

To solve the mantle plume mystery, Hans Thybo and colleagues will lower advanced seismographic equipment onto the Atlantic seabed in a 1000 km radius surrounding Iceland – well into the zone of Greenland’s bedrock and around the Faroe Islands.

“Using new methods and instruments, we can take geologic measurements much deeper within the Earth than before. Now, down to 500 and 1000 kilometers! Methods in current use, by the oil industry among others, provide information for areas down to between 6 and 10 kilometers,” explains Professor Thybo.

The mantle plume mystery

Determining the existence of mantle plumes has been a fundamental question since the development of plate tectonics in the 1960’s and 70’s. Plate tectonics is a geophysics-geologic theory built upon the premise that Earth’s exterior is divided into plates which shift in relation to one another. Science, the world’s leading scientific journal, regards the mantle plume mystery as the today’s most important geoscientific question. Are mantle plumes a means of transporting heat from the Earth’s core to its surface? Or, is heat from the center of the Earth diffused more evenly throughout the planet’s oceans and continents?

Future oil exploration

Professor Hans Thybo has previously attracted international attention with his examination of Lake Baikal, the planet’s deepest lake, found in Siberia. At the time, tons of dynamite were bored underground and set off at a depth of 70 metres to investigate the unique Baikal Rift Zone, upon which the 1700 metre deep Lake Bailkal is saddled. Rift Zones are elongated geologic depressions, also known as crustal fractures. They can plunge up to ten kilometres into the Earth’s crust and contribute to the fracturing of tectonic plates upon which continents rest.

“The Baikal project allowed us to follow sound waves, produced by explosions, into the Earth’s interior. The same method will be deployed up in Iceland. Using the recordings of earthquake waves and so called ‘air canons’ loaded with compressed air, we will be able to examine the composition of rock deep within the Earth,” explains Thybo, who adds that the technique might also be adapted for oil exploration.

Terrestrial conditions below a depth of 50 kilometres will be investigated by recording the shock waves of distant earthquakes. This monitoring requires that the instruments be stationed on the Atlantic seabed for two years. Beyond their work shedding a vigorous and much anticipated new light upon the mantle plume mystery, DanSeis will also address other basic research challenges, such as investigating the origin of mountains found in the North Atlantic area – Norway and Greenland included.

DanSeis has been awarded ?3.35 million by the Danish Ministry of Science, Innovation and Higher Education. DanSeis is headquartered at the University of Copenhagen’s Department of Geography and Geology and will begin operations from Spring 2012.

Santorini: The ground is moving again in paradise

Georgia Tech associate professor Andrew Newman has positioned more than 20 GPS stations on Santorini. Some have moved as much as 9 cm since the caldera reawakened in January 2011. Should the volcano erupt underwater, it could produce local tsunamis, which could be dangerous for cruise ships that commonly visit the tourist attraction. -  Georgia Institute of Technology
Georgia Tech associate professor Andrew Newman has positioned more than 20 GPS stations on Santorini. Some have moved as much as 9 cm since the caldera reawakened in January 2011. Should the volcano erupt underwater, it could produce local tsunamis, which could be dangerous for cruise ships that commonly visit the tourist attraction. – Georgia Institute of Technology

Do a Google image search for “Greece.” Before you find pictures of the Parthenon or Acropolis, you’ll see several beautiful photos of Santorini, the picturesque island in the Aegean Sea. The British Broadcasting Company named it the world’s best island in 2011. Santorini is a tourist magnet, famous for its breathtaking, cliff side views and sunsets.

It’s also a volcanic island that has been relatively calm since its last eruption in 1950. Until now. The Santorini caldera is awake again and rapidly deforming at levels never seen before. Georgia Tech Associate Professor Andrew Newman has studied Santorini since setting up more than 20 GPS stations on the island in 2006.

“After decades of little activity, a series of earthquakes and deformation began within the Santorini caldera in January of 2011,” said Newman, whose research is published by Geophysical Research Letters. “Since then, our instruments on the northern part of the island have moved laterally between five and nine centimeters. The volcano’s magma chamber is filling, and we are keeping a close eye on its activity.”

Newman, a geophysicist in the School of Earth and Atmospheric Sciences, cannot be certain whether an eruption is imminent since observations of such activity on these types of volcanoes are limited. In fact, similar calderas around the globe have shown comparable activity without erupting. However, Newman says the chamber has expanded by 14 million cubic meters since last January. That means enough magma has been pumped into the chamber to fill a sphere three football fields across.

Should Santorini erupt, Newman says it will likely be comparable to what the island has seen in the last 450 years.

“That could be dangerous,” notes Newman. “If the caldera erupts underwater, it could cause local tsunamis and affect boat traffic, including cruise ships, in the caldera. Earthquakes could damage homes and produce landslides along the cliffs.”

More than 50,000 tourists a day flock to Santorini in the summer months (from May to October). It’s common to see as many as five cruise ships floating above the volcano.

Santorini is the site of one of the largest volcanic events in human history. The Minoan eruption, which occurred around 1650 B.C., buried the major port city of Akrotiri with more than 20 meters of ash and created Santorini’s famous, present-day cliffs. Newman says such history will likely not repeat itself any time soon. Such an eruption comes along once every 100,000 years, and the current inflation in the magma chamber is less than 1 percent of the Minoan blast.

To see an animation of Newman’s GPS stations and the angles of movement, click here.

A new theory on the formation of the oldest continents

The earth’s structure can be compared to an orange: its crust is the peel supported by the earth’s heavy mantle. That peel is made up of a continental crust 30 to 40 kilometers thick. It is much lighter than the thinner oceanic crust and protrudes from the earth’s mantle because of its lower density, like an iceberg in the sea. “According to the current theory, the first continental crusts were formed when tectonic plates would collide, submerging oceanic crusts into the earth’s mantle, where they would partially melt at a depth of approximately 100 kilometers. That molten rock then ascended to the earth’s surface and formed the first continents,” says adjunct professor Dr. Thorsten Nagel of the Steinmann Institute of Geosciences at the University of Bonn, lead author of the study. The theory has been supported by the oldest known continental rocks – approximately 3.8 billion years old – found in western Greenland.

Following trace elements

The composition of the continental crust corresponds to a semiliquid version of the oceanic crust melted by 10 to 30 percent of its original state. Unfortunately, the concentrations of the main chemical components in the re-solidified rock do not provide much information about what depth the fusion occurred at. “In order to find that out, you have to know what minerals the remaining 70 to 90 percent of the oceanic crust consisted of,” explains Prof. Dr. Carsten Münker of the Institute of Geology and Mineralogy at the University of Cologne. Researchers from Bonn and Cologne have now analyzed the Greenlandic rocks for different elements occurring at various high concentrations, also know as trace elements. “Trace elements provide geologists with a window to the origin of continental crust,” says Prof. Münker. “With their help, we can identify minerals in the residual rock that were deposited in the depths by the molten rock.”

Before the magma separated from the bedrock, the semifluid rock and the leftover solid minerals actively exchanged trace elements. “Different minerals have characteristic ways of separating when trace elements are smelted. In other words, the concentration of trace elements in the molten rock provide a fingerprint of the residual bedrock,” explains Dr. Elis Hoffmann from Bonn, coauthor of the study. The concentration of trace elements in the oldest continental rock allows geoscientists to reconstruct possible bedrock based on their minerals and thus determine at what depth the continental crust originated.

The oceanic crust did not have to descend

Using computers, the scientists simulated the composition of bedrock and molten rock that would emerge from partially melting the oceanic crust at various depths and temperatures. They then compared the data calculated for the molten rock with the actual concentration of trace elements in the oldest continental rocks. “Our results paint a surprising picture,” Dr. Nagel reports. “The oceanic crust did not have to descend to a depth of 100 kilometers to create the molten rock that makes up the rocks of the first continents.” According to the calculations, a depth of 30 to 40 kilometers is much more probable.

The primeval oceanic crust could have ‘oozed’ continents

…it could definitely have had the power to do so in the Archean eon. Four billion years ago, the gradually cooling earth was still significantly warmer than it is today. The oceanic crust could have simply ‘oozed’ continents at the same time that other geological processes were occurring, like volcanism, orogeny, and the influx of water. “We think it is unlikely that the contents were formed into subduction zones. Whether or not tectonic plates of the primordial earth had such zones of subsidence is still a matter of debate,” says the geologist from Bonn.

Mapping the Moho with GOCE

The first global high-resolution map of the boundary between Earth’s crust and mantle – the Moho – has been produced based on data from ESA’s GOCE gravity satellite. Understanding the Moho will offer new clues into the dynamics of Earth’s interior.

Earth’s crust is the outermost solid shell of our planet. Even though it makes up less than 1% of the volume of the planet, the crust is exceptionally important not just because we live on it, but because is the place where all our geological resources like natural gas, oil and minerals come from.
The crust and upper mantle is also the place where most geological processes of great importance occur, such as earthquakes, volcanism and orogeny.

Until just a century ago, we didn’t know Earth has a crust. In 1909, Croatian seismologist Andrija Mohorovičić found that at about 50 km underground there is a sudden change in seismic speed.

Ever since, that boundary between Earth’s crust and underlying mantle has been known as the Mohorovičić discontinuity, or Moho.

Even today, almost all we know about Earth’s deep layers comes from two methods: seismic and gravimetric.

Seismic methods are based on observing changes in the propagation velocity of seismic waves between the crust and mantle.

Gravimetry looks at the gravitational effect due to the density difference caused by the changing composition of crust and mantle.

But the Moho models based on seismic or gravity data are usually limited by poor data coverage or data being only available along single profiles.

The GOCE Exploitation for Moho Modelling and Applications project – or GEMMA – has now generated the first global high-resolution map of the boundary between Earth’s crust and mantle based on data from the GOCE satellite.

GOCE measures the gravity field and models the geoid with unprecedented accuracy to advance our knowledge of ocean circulation, which plays a crucial role in energy exchanges around the globe, sea-level change and Earth interior processes.

GEMMA’s Moho map is based on the inversion of homogenous well-distributed gravimetric data.

For the first time, it is possible to estimate the Moho depth worldwide with unprecedented resolution, as well as in areas where ground data are not available. This will offer new clues for understanding the dynamics of Earth’s interior, unmasking the gravitational signal produced by unknown and irregular subsurface density distribution.

GEMMA is being carried out by Italian scientist Daniele Sampietro, and is funded by the Politecnico di Milano and ESA’s Support To Science Element under the Changing Earth Science Network initiative.

This initiative supports young scientists at post-doctoral level in ESA Member States to advance our knowledge in Earth system science by exploiting the observational capacity of ESA missions.

New research helps to identify ancient droughts in China

Drought events are largely unknown in Earth’s history, because reconstruction of ancient hydrological conditions remains difficult due to lack of proxy. New GEOLOGY research supported by China’s NNSF and MS&T uses a microbial lipid proxy of highly alkaline conditions to identify enhanced aridity in Miocene sediments on the Tibetan Plateau. This enhanced aridity is associated with significant uplift of the Tibetan Plateau nine million years ago.

According to the study’s lead author, Xie Shucheng of the China University of Geosciences at Wuhan, the identification of ancient droughts and associated alkaline soils is particularly challenging at the regional or local level, and is beyond the predictive capabilities of available general circulation models (GCMs). GCMs, which are used to understand physical processes in the Earth surface system, are advanced tools for simulation of long-term temperature changes.

This new research proposes a microbial lipid proxy of highly alkaline conditions and enhanced aridity on the basis of investigation of modern Chinese soils. In modern Chinese soils, more abundant archaeal lipids known as iGDGTs (isoprenoid glycerol dialkyl glycerol tetraethers) relative to bacterial branched GDGTs were found to be associated with alkaline conditions and enhanced aridity. As a consequence, the ratio of archaeal GDGTs to bacterial GDGTs is indicative of the occurrence of ancient alkalinity and enhanced aridity.

Xie and colleagues also used the microbial lipid proxy to identify the enhanced aridity and alkalinity of Late Miocene sediments from the Zhada basin, which is located in the southwestern Tibetan Plateau, ~1000 km west of Lhasa. They find that the highly alkaline conditions and enhanced aridity identified in these sediments are associated with the most significant uplift of the Tibetan Plateau nine million years ago. The study’s findings suggest that abrupt uplifts in the Tibetan Plateau can cause enhanced aridity in central Asia and a consequential development of alkaline soils.

Northeastern geology: Careers, hazards, human impacts, and (of course) fossils

Geoscientists from across the northeastern U.S. and beyond will convene in Hartford, Connecticut, on 18-20 March to discuss new science, expand on existing science, and explore the geologic, historic, and scenic wonders of the region. Sessions and field trips cover geoscience careers, Appalachian tectonics, the evolution of northeastern rivers, human impacts on estuaries and urban watersheds, mercury contamination, mineralogy and medicine, K-16 education, the “dinosaur renaissance,” and the geology of Walden Pond.

Selected Highlights of the Scientific Program

The scientific program is comprised of oral and poster presentations organized into 26 themed sessions plus an array of research in general discipline areas. Go to www.geosociety.org/Sections/ne/2012mtg/techprog.htm to learn more.

Sunday, 18 March


Historical Perspectives: 250 Years of Geology in the Northeast. William R. Brice of the University of Pittsburgh at Johnstown and Sally Newcomb, presiding. Geological studies of northeastern North America have had a profound influence on the understanding of local geological history and on clarifying Earth’s history. This session includes a variety of presentations on the evolution of geological understanding in this region over the past 250 years.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_29747.htm, 8 to 10 a.m. (session 4).

Paper 4-3: Stratigraphy and Structure of the Rocks Underlying Boston Harbor: New Insights on the Cambridge Argillite and Associated Diamictites and Diabase Sills. Peter J. Thompson, University of New Hampshire; Joseph P. Kopera, Office of the Massachusetts State Geologist; and Daniel R. Solway, Northern Arizona University: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_199957.htm.

Women in the Geosciences: Past, Present, and Future. Kristine Larsen of Central Connecticut State University and Heidi Hoffower of Chevron Corp., presiding. Historically, women faced numerous challenges as they attempted to gain a foothold in the geoscience community. Today, women have still not achieved parity with their male colleagues. This session will explore issues of gender and the geosciences, applying the lessons of the past and present in order to promote success for women in the future geoscience workforce.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_29748.htm, 10:20 a.m. to noon (session 5.).

Paper 5-1: Delia Woodruff Godding, Jane Kilby Welsh, and the Religion of Geology in New England. Author: Kristine Larsen, Central Connecticut State University: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_199730.htm.


Geologic Hazards and Climate Change in the Northeast: Impacts and Opportunities. Nicholas K. Coch of CUNY Queens College and Laurence R. Becker of the Vermont Geological Survey, presiding. This session covers geologic hazards such as earthquakes, landslides, flooding, ground subsidence, and fluvial and coastal erosion and the impacts of hurricanes and nor’easters, as well as possible future impacts of climate change (including sea-level rise).

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_29752.htm, 1:30 to 5:30 p.m. (session 15).

Paper 15-9: Hurricane Irene — Lessons for the Northeast. Author: Nicholas K. Coch, CUNY Queens College: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_199121.htm.

News from the Newark Supergroup (Posters). Advocate: Elizabeth Gierlowski-Kordesch, Ohio University. This session follows a morning of oral presentations on the newest research on East Coast Triassic-Jurassic Newark Supergroup basins.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_30423.htm; 1:30 to 5:30 p.m.; authors will be present at their poster 2 to 4 p.m. (session 22).

Paper 22-1: Uncovering the Main Trackway at Dinosaur State Park (Rocky Hill, CT) in Preparation for the 50th Anniversary Rededication. Author: Hugo Thomas, Emeritus State Geologist, Connecticut and six others: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_200384.htm.

In 1966, dinosaur footprints were discovered at what is now Dinosaur State Park in Rocky Hill, Connecticut, USA. Only about a third of the tracks were covered by a roof, and the more than 1,500 unsheltered tracks were reburied in 1976 after they started to show signs of deterioration. Recently, a small area of the buried tracks was uncovered to assess their condition in order to help revive plans for constructing a permanent structure over the trackways.

Monday, 19 March


The Legacy of Humans and Glaciation in Northeastern Rivers (Posters). Advocates: Will Ouimet and Denise Burchsted of the University of Connecticut and Jon Woodruff of the University of Massachusetts. This session covers the evolution of northeastern rivers affected by glaciation, post-glacial evolution, and human activity and will include case studies and lessons in mitigation.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_30416.htm; authors will be present at their poster 9 to 11 a.m. (session 30

Paper 30-6: A River Runs through It — The Geomorphic Impacts of the Vermont Interstate Highway System. Authors: Analeisha M. Vang, University of Vermont; Paul R. Bierman, University of Vermont: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_200388.htm.


Mercury Dynamics in Northeastern North America. Johan (Joop) C. Varekamp of Wesleyan University and Robert Mason of the University of Connecticut, presiding. Mercury is a pervasive contaminant in almost every lake, wetland, and estuary. Fish advisories have been issued for most lakes in New England. Contributions to this session will include presentations on contamination geochemistry and fate and transport of mercury in air, water, and sediment of lacustrine, coastal, and riverine environments, especially from northeastern North America.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_29741.htm, 1:30?:30 p.m. (session 36).

Paper 36-7: Historic Mercury Sources in Connecticut: From Fashion to Factories. Author: Johan (Joop) C. Varekamp, Wesleyan University: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_200195.htm.

Tuesday, 20 March


State and Fate of Urban Watersheds in the Northeast. Jonathan R. Gourley of Trinity College and Suzanne O’Connell of Wesleyan University, presiding. Urbanization, increased impervious surfaces, and storm-water runoff have had, and will continue to have, serious impacts on many watersheds throughout the northeastern U.S. and adjoining parts of Canada. This session features research that focuses on the environmental issues that currently face urban watersheds.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_29738.htm, 8 a.m.-noon (session 47)

Paper 47-2: Geomorphological approach to toxic trace metal distribution across channel bar deposits in the park river watershed, Hartford, CT. Kelsey Semrod and Jonathan Gourley, Trinity College: http://gsa.confex.com/gsa/2012NE/finalprogram/abstract_199419.htm

Mineralogy, Igneous, Metamorphic Petrology, Volcanology. LeeAnn Srogi of West Chester University, presiding. This discipline session covers the mineralogy, petrology, and volcanology of the northeastern U.S., Askja volcano, Iceland; Bou Dahar mining district, Morocco; Prydz Bay, Antarctica; and Bulqiza Ultramafic Massif, Albania; and also includes a look at minerals and medicine.

Abstracts: http://gsa.confex.com/gsa/2012NE/finalprogram/session_30408.htm, 8 a.m. to noon (session 44).

View the complete session schedule by day or search the program by keywords at http://gsa.confex.com/gsa/2012NE/finalprogram/. Click on session titles for a list of presentations, and click on presentations for the individual abstracts.

Find complete meeting information at www.geosociety.org/Sections/ne/2012mtg/.

Find local contact information at www.geosociety.org/Sections/ne/2012mtg/contact.htm.


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 2011 or 2012.
  • PIOs of scientific societies, educational institutions, and government agencies.

Present media credentials to William Cox onsite at the GSA registration desk to obtain a badge for media access. 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.

For additional information and assistance, contact Christa Stratton, GSA Director of Communications, at the address above.

Mechanism for Burgess Shale-type preservation

The Burgess Shale of British Columbia is arguably the most important fossil deposit in the world, providing an astounding record of the Cambrian “Explosion,” the rapid flowering of complex life from single-celled ancestors. While most of the fossil record is comprised of shells, teeth and bones, the Burgess Shale preserves the softer bits-the eyes, guts, gills and other delicate structures-of animals belonging to Earth’s earliest complex ecosystems a half a billion years ago. The process for this extraordinary preservation remained a mystery since the initial discovery of the Burgess Shale in 1909 until now.

A team of researchers led by Robert Gaines, of Pomona College (USA), and Emma Hammarlund, of the Nordic Center for Earth Evolution (Denmark), claims to have unlocked the mystery of the Burgess Shale in their study, “Mechanism for Burgess Shale-type preservation,” published in Monday the 5th of March in the Proceedings of the National Academy of Sciences. In addition to Gaines and Hammarlund, the team includes researchers from t Yunnan University (China), the University of Leicester (UK) and Guizhou University(China).

The team collected evidence from the Burgess Shale, two new drill cores from the Chengjiang deposit in Yunnan Province, China, and from five other principal Burgess Shale-type deposits in Utah and China. Using geochemical analysis involving the sulfur isotypes from pyrite (fool’s gold), they found a striking global pattern that unlocks the key to the unusual preservation process.

The process begins with the very rapid burial of organisms in mud layers with little to no oxygen. The critical discovery by the research team was a layer of calcium carbonate cement, in all of the sites, laid on the sea floor soon after burial of the fossils in mud. This mineral carpet acted as a barrier to the microbial communities that would normally consume soft tissue organisms in two-three weeks. Because the microbes were prevented from degrading the soft tissues completely, the organic remains of animals were conserved, leading to the preservation of the extraordinary fossils found today.

“What turned out to be the important key for this type of preservation is the chemistry of the global sea water,” explains Gaines. “The preservation was greatly aided by enhanced calcium carbonate concentrations in the Cambrian oceans and by depletion of oxygen and sulfate. Importantly, low oxygen concentrations in the global oceans during this interval of time limited the amount of sulfate, an important microbial nutrient.”

In the past, researchers have focused on the fossils themselves, rather than the details of the sediments and their chemistry. Gaines and Hammarlund found it was necessary to unlock the mystery of the strange preservation-a sign that the environment was not normal.

The drill cores from the Chengjiang site were important because the heavy rains from the Himalayan monsoons in the area leach minerals, including pyrite and calcium carbonate, from the rocks that are exposed on the surface. With these cores, the team’s unique collection of samples led to the recognition that unique aspects of early Paleozoic seawater chemistry that were key to the unusual Burgess-type soft-bodied fossil preservation-the low sulfate concentration, low-oxygen bottom water conditions, and the mineral carpet that aided in choking the hungry microbes-was a striking global pattern.

“I had little idea of what to expect from the geochemical data, which rarely can provide a ‘silver bullet,’ says Gaines. “I was literally floored. I have rarely seen geochemical data so convincing. My initial hypothesis was validated by a consistent and worldwide pattern.”

The Blue Planet’s new water budget

Investigating the history of water on Earth is critical to understanding the planet’s climate. One central question is whether Earth has always had the same amount of water on and surrounding it, the same so-called “water budget”. Has Earth gained or lost water from comets and meteorites? Has water been lost into space? New research into the Earth’s primordial oceans conducted by researchers at the Natural History Museum of Denmark at the University of Copenhagen and Stanford University revisits Earth’s historical water budget. The results have just been published in the Proceedings of the National Academy of Sciences (PNAS) journal.

Water accounts for about ½ of a thousandth of the Earth’s total mass, despite the fact that roughly 70% of the planet’s surface is covered by this substance so vital to survival. Indeed, water is a relatively “rare substance” on our “Blue Planet”.

Where does water come from?

“One of the absolutely most intriguing things about Earth is that there are oceans of water and that the presence of liquid water has enabled the existence of life on Earth. Therefore, questions concerning how Earth got its oceans, where the water came from and – whether we are losing or gaining water from space – are fundamental questions in the understanding of the Earth’s history,” says Emily Pope of the Nordic Center for Earth Evolution at the Natural History Museum of Denmark, University of Copenhagen.

Earth’s “little bit” of water is divided among a variety of reservoirs. Therefore, a fairly accurate assessment of how much water currently exists on Earth can be made. But now, Emily Pope and her colleagues at the Natural History Museum of Denmark and Stanford University have also been able to determine that liquid water was also in existence upon the young Earth, billions of years ago. And, more consequentially, they have been able to approximate the ancient water budget.

The researchers have done this by examining 3.8 billion year old minerals from Greenland which are derived from the Earth’s primordial oceans.

A “minor” loss

“We have managed to reconstruct the isotopic composition of 3.8 billion-year-old seawater using mineral samples from the Isua-rocks in Greenland. The results demonstrate that the young planet’s oceans, in relation to those of today, had proportionately more “normal water” than “heavy water” in them. We can explain this difference by the fact that Earth has lost less than ¼ of its water budget over the last roughly 4 billion years,” says Pope.

It may sound like a lot of liquid, but it’s a surprise for researchers that the Earth’s water budget has been so relatively stable for so many years. The new findings concerning the historical development of oceans also support new theories and suggested solutions to “the faint young Sun paradox”. Theories challenging the paradox were propounded by a number of researchers from the Natural History Museum of Denmark and Stanford in 2010.

About the faint early Sun paradox

In 1972, the late, world renowned astronomer and his colleague, George Mullen, formulated “the faint early Sun paradox.” The paradox addressed the relative stability of the earth’s climate over the 4.5 billion years of its existence in relation to the fact that during the same period, solar radiation has increased by 25-30 percent.

The paradoxical question that arose from the scientists was why the earth’s surface, during the planet’s infancy, was not covered by ice, when the sun’s rays were much weaker than they are today. One possible solution to the paradox, among others, was proposed by the American atmospheric researcher Jim Kasting in 1993. He performed theoretical calculations which showed that 4 billion-years-ago, 30 percent of the Earths atmosphere was composed of CO2. The theory was that the impact of this large amount of greenhouse gas insulated the planet and prevented the oceans from freezing over.

An abundance of atmospheric CO2 however, was not the ice-limiting factor. Instead, a much thinner layer of cloud played a major role in keeping ice at bay. Furthermore, the Earth was covered by ocean. This meant that the Sun’s relatively unimpeded rays could warm the massive ocean which in turn could store heat and prevent the freezing of its surface, according to the research group from University of Copenhagen and Stanford. This is their current answer to the long-standing riddle.

Listening to the 9.0-magnitude Japanese earthquake

Last year’s 9.0-magnitude Tohoku-Oki, Japan, earthquake was the fourth largest since 1900. However, because of thousands of seismometers in the region and Japan’s willingness to share their measurements with the rest of the world, the Tohoku-Oki quake is the best-recorded earthquake of all-time.

This plethora of information is allowing scientists to share their findings in unique ways. Zhigang Peng, associate professor in Georgia Tech’s School of Earth and Atmospheric Sciences, has converted the earthquake’s seismic waves into audio files. The results allow experts and general audiences to “hear” what the quake sounded like as it moved through the earth and around the globe.

“We’re able to bring earthquake data to life by combining seismic auditory and visual information,” said Peng, whose research appears in the March/April edition of Seismological Research Letters. “People are able to hear pitch and amplitude changes while watching seismic frequency changes. Audiences can relate the earthquake signals to familiar sounds such as thunder, popcorn popping and fireworks.”

The different sounds can help explain various aspects of the earthquake sequence, including the mainshock and nearby aftershocks. For example, this measurement was taken near the coastline of Japan between Fukushima (the nuclear reactor site) and Tokyo. The initial blast of sound is the 9.0 mainshock. As the earth’s plates slipped dozens of meters into new positions, aftershocks occured. They are indicated by “pop” noises immediately following the mainshock sound. These plate adjustments will likely continue for years.

As the waves from the earthquake moved through the earth, they also triggered new earthquakes thousands of miles away. In this example, taken from measurements in California, the quake created subtle movements deep in the San Andreas Fault. The initial noise, which sounds like distant thunder, corresponds with the Japanese mainshock. Afterwards, a continuous high-pitch sound, similar to rainfall that turns on and off, represents induced tremor activity at the fault. This animation not only help scientists explain the concept of distant triggering to general audiences, but also provides a useful tool for researchers to better identify and understand such seismic signals in other regions.

The human ear is able to hear sounds for frequencies between 20 Hz and 20 kHz, a range on the high end for earthquake signals recorded by seismometers. Peng, graduate student Chastity Aiken and other collaborators in the U.S. and Japan simply played the data faster than true speed to increase the frequency to audible levels. The process also allows audiences to hear data recorded over minutes or hours in a matter of seconds.

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This recording was taken about 90 miles from the Japanese earthquake’s epicenter. There are two distinct sound waves. Both are caused by the mainshock. A ‘pop’ is heard 90 seconds (in actual time) after the main event. This pop wasn’t recorded at any other nearby stations, leading Georgia Tech Associate Professor Zhigang Peng to believe that either the ground shifted immediately under the measuring station, or the hill slope where the station sits in helps to amplify the shaking. It was the strongest reading he found — a ground acceleration of nearly three g. – Georgia Institute of Technology

Study supports theory of extraterrestrial impact

This is James Kennett. -  	University of California - Santa Barbara
This is James Kennett. – University of California – Santa Barbara

A 16-member international team of researchers that includes James Kennett, professor of earth science at UC Santa Barbara, has identified a nearly 13,000-year-old layer of thin, dark sediment buried in the floor of Lake Cuitzeo in central Mexico. The sediment layer contains an exotic assemblage of materials, including nanodiamonds, impact spherules, and more, which, according to the researchers, are the result of a cosmic body impacting Earth.

These new data are the latest to strongly support of a controversial hypothesis proposing that a major cosmic impact with Earth occurred 12,900 years ago at the onset of an unusual cold climatic period called the Younger Dryas. The researchers’ findings appear today in the Proceedings of the National Academy of Sciences.

Conducting a wide range of exhaustive tests, the researchers conclusively identified a family of nanodiamonds, including the impact form of nanodiamonds called lonsdaleite, which is unique to cosmic impact. The researchers also found spherules that had collided at high velocities with other spherules during the chaos of impact. Such features, Kennett noted, could not have formed through anthropogenic, volcanic, or other natural terrestrial processes. “These materials form only through cosmic impact,” he said.

The data suggest that a comet or asteroid — likely a large, previously fragmented body, greater than several hundred meters in diameter — entered the atmosphere at a relatively shallow angle. The heat at impact burned biomass, melted surface rocks, and caused major environmental disruption. “These results are consistent with earlier reported discoveries throughout North America of abrupt ecosystem change, megafaunal extinction, and human cultural change and population reduction,” Kennett explained.

The sediment layer identified by the researchers is of the same age as that previously reported at numerous locations throughout North America, Greenland, and Western Europe. The current discovery extends the known range of the nanodiamond-rich layer into Mexico and the tropics. In addition, it is the first reported for true lake deposits.

In the entire geologic record, there are only two known continent-wide layers with abundance peaks in nanodiamonds, impact spherules, and aciniform soot. These are in the 65-million-year-old Cretaceous-Paleogene boundary layer that coincided with major extinctions, including the dinosaurs and ammonites; and the Younger Dryas boundary event at 12,900 years ago, closely associated with the extinctions of many large North American animals, including mammoths, mastodons, saber-tooth cats, and dire wolves.

“The timing of the impact event coincided with the most extraordinary biotic and environmental changes over Mexico and Central America during the last approximately 20,000 years, as recorded by others in several regional lake deposits,” said Kennett. “These changes were large, abrupt, and unprecedented, and had been recorded and identified by earlier investigators as a ‘time of crisis.’ “