Potential methane reservoirs beneath Antarctica

The new study demonstrates that old organic matter in sedimentary basins located beneath the Antarctic Ice Sheet may have been converted to methane by micro-organisms living under oxygen-deprived conditions. The methane could be released to the atmosphere if the ice sheet shrinks and exposes these old sedimentary basins.

The researchers estimate that 50 per cent of the West Antarctic Ice Sheet (1 million km2) and 25 per cent of the East Antarctic Ice Sheet (2.5 million km2) overlies preglacial sedimentary basins, containing about 21,000 billion tonnes of organic carbon.

Team leader, Professor Wadham said: “This is an immense amount of organic carbon, more than ten times the size of carbon stocks in northern permafrost regions. Our laboratory experiments tell us that these sub-ice environments are also biologically active, meaning that this organic carbon is probably being metabolised to carbon dioxide and methane gas by microbes.”

The researchers then numerically simulated the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model. They found that sub-ice conditions favour the accumulation of methane hydrate (that is, methane trapped within a structure of water molecules, forming a solid similar to regular ice).

They also calculated that the potential amount of methane hydrate and free methane gas beneath the Antarctic Ice Sheet could be up to 400 billion tonnes (that is, 400 Pg of carbon), a similar order of magnitude to some estimates made for Arctic permafrost. The predicted shallow depth of these potential reserves also makes them more susceptible to climate forcing than other methane hydrate reserves on Earth.

Dr Sandra Arndt, a NERC fellow at the University of Bristol who conducted the numerical modelling, said: “It’s not surprising that you might expect to find significant amounts of methane hydrate trapped beneath the ice sheet. Just like in sub-seafloor sediments, it is cold and pressures are high which are important conditions for methane hydrate formation.”

If substantial methane hydrate and gas are present beneath the Antarctic Ice Sheet, methane release during episodes of ice-sheet collapse could act as a positive feedback on global climate change during past and future ice-sheet retreat.

Professor Slawek Tulaczyk, glaciologist from the University of California, Santa Cruz, said: “Our study highlights the need for continued scientific exploration of remote sub-ice environments in Antarctica, because they may have far greater impact on Earth’s climate system than we have appreciated in the past.”

Past tropical climate change linked to ocean circulation

A new record of past temperature change in the tropical Atlantic Ocean’s subsurface provides clues as to why the Earth’s climate is so sensitive to ocean circulation patterns, according to climate scientists at Texas A&M University.

Geological oceanographer Matthew Schmidt and two of his graduate students teamed up with Ping Chang, a physical oceanographer and climate modeler, to help uncover an important climate connection between the tropics and the high latitude North Atlantic. Their new findings are in the current issue of PNAS (Proceedings of the National Academy of Sciences).

The researchers used geochemical clues in fossils called foraminifera, tiny sea creatures with a hard shell, collected from a sediment core located off the northern coast of Venezuela, to generate a 22,000-year record of past ocean temperature and salinity changes in the upper 1,500 feet of water in the western tropical Atlantic. They also conducted global climate model simulations under the past climate condition to interpret this new observational record in the context of changes in the strength of the global ocean conveyor-belt circulation.

“What we found was that subsurface temperatures in the western tropical Atlantic rapidly warmed during cold periods in Earth’s past,” Schmidt explains.

“Together with our new modeling experiments, we think this is evidence that when the global conveyor slowed down during cold periods in the past, warm subsurface waters that are normally trapped in the subtropical North Atlantic flowed southward and rapidly warmed the deep tropics. When the tropics warmed, it altered climate patterns around the globe.”

He notes that as an example, if ocean temperatures were to warm along the west coast of Africa, the monsoon rainfall in that region would be dramatically reduced, affecting millions of people living in sub-Saharan Africa. The researchers also point out that the southward flow of ocean heat during cold periods in the North Atlantic also causes the band of rainfall in the tropics known as the Intertropical Convergence Zone to migrate southward, resulting in much drier conditions in northern South American countries and a wetter South Atlantic.

“Evidence is mounting that the Earth’s climate system has sensitive triggers that can cause abrupt and dramatic shifts in global climate,” Schmidt said.

“What we found in our subsurface reconstruction was that the onset of warmer temperatures, thought to reflect the opening of this ‘gateway’ mechanism, occurred in less than a few centuries. It also tells us that it might be a good idea to monitor subsurface temperatures in the western tropical Atlantic to assess how the strength of the ocean conveyor might be changing over the next few decades as Earth’s climate continues to warm.”

“One way to prepare for future climate change is to increase our understanding of how it has operated in the recent past.

Antarctic ice sheet quakes shed light on ice movement and earthquakes

Analysis of small, repeating earthquakes in an Antarctic ice sheet may not only lead to an understanding of glacial movement, but may also shed light on stick slip earthquakes like those on the San Andreas fault or in Haiti, according to Penn State geoscientists.

“No one has ever seen anything with such regularity,” said Lucas K. Zoet, recent Penn State Ph. D. recipient, now a postdoctoral fellow at Iowa State University. “An earthquake every 25 minutes for a year.”

The researchers looked at seismic activity recorded during the Transantarctic Mountains Seismic Experiment from 2002 to 2003 on the David Glacier in Antarctica, coupled with data from the Global Seismic Network station Vanda. They found that the local earthquakes on the David Glacier, about 20,000 identified, were predominantly the same and occurred every 25 minutes give or take five minutes.

The researchers note in the current Nature Geoscience that, “The remarkable similarity of the waveforms ? indicates that they share the same source location and source mechanisms.” They suggest that “the same subglacial asperity repeatedly ruptures in response to steady loading from the overlying ice, which is modulated by stress from the tide at the glacier front.”

“Our leading idea is that part of the bedrock is poking through the ductile till layer beneath the glacier,” said Zoet.

The researchers have determined that the asperity — or hill — is about a half mile in diameter.

The glacier, passing over the hill, creates a stick slip situation much like that on the San Andreas fault. The ice sticks on the hill and stress gradually builds until the energy behind the obstruction is high enough to move the ice forward. The ice moves in a step-by-step manner rather than smoothly.

But motion toward the sea is not the only thing acting on the ice streaming from David glacier. Like most glaciers near oceans, the edge of the ice floats out over the water and the floating ice is subject to the action of tides.

“When the tide comes in it pushes back on the ice, making the time between slips slightly longer,” said Sridhar Anandakrishnan, professor of geoscience. “When the tide goes out, the time between slips decreases.”

However, the researchers note that the tides are acting at the ground line, a long way from the location of the asperity and therefore the effects that shorten or lengthen the stick slip cycle are delayed.

“This was something we didn’t expect to see,” said Richard B. Alley, Evan Pugh Professor of Geosciences. “Seeing it is making us reevaluate the basics.”

He also noted that these glacial earthquakes, besides helping glaciologists understand the way ice moves, can provide a simple model for the stick slip earthquakes that occur between landmasses.

“We have not completely explained how ice sheets flow unless we can reproduce this effect,” said Alley. “We can use this as a probe and look into the physics so we better understand how glaciers move.”

Before 2002, this area of the David glacier flowed smoothly, but then for nearly a year the 20-minute earthquake intervals occurred and then stopped. Something occurred at the base of the ice to start and then stop these earthquakes.

“The best idea we have is that during those 300 days, a dirty patch of ice was in contact with the mount, changing the way stress was transferred,” said Zoet. “The glacier is experiencing earthquakes again, although at a different rate. It would be nice to study that.”

Unfortunately, the seismographic instruments that were on the glacier in 2002 no longer exist, and information is coming from only one source at the moment.

Drastic desertification

The Dead Sea, a salt sea without an outlet, lies over 400 meters below sea level. Tourists like its high salt content because it increases their buoyancy. “For scientists, however, the Dead Sea is a popular archive that provides a diachronic view of its climate past,” says Prof. Dr. Thomas Litt from the Steinmann-Institute for Geology, Mineralogy and Paleontology at the University of Bonn.

Using drilling cores from riparian lake sediments, paleontologists and meteorologists from the University of Bonn deduced the climate conditions of the past 10,000 years. This became possible because the Dead Sea level has sunk drastically over the past years, mostly because of increasing water withdrawals lowering the water supply.

Oldest pollen analysis

In collaboration with the GeoForschungsZentrum Potsdam (German Research Centre for Geosciences) and Israel’s Geological Service, the researchers took a 21 m long sediment sample in the oasis Ein Gedi at the west bank of the Dead Sea. They then matched the fossil pollen to indicator plants for different levels of precipitation and temperature. Radiocarbon-dating was used to determine the age of the layers. “This allowed us to reconstruct the climate of the entire postglacial era,” Prof. Litt reports. “This is the oldest pollen analysis that has been done on the Dead Sea to date.”

In total, there were three different formations of vegetation around this salt sea. In moist phases, a lush, sclerophyll vegetation thrived as can be found today around the Mediterranean Sea. When the climate turned drier, steppe vegetation took over. Drier episodes yet were characterized by desert plants. The researchers found some rapid changes between moist and dry phases.

Transforming pollen data into climate information

The pollen data allows inferring what kinds of plants were growing at the corresponding times. Meteorologists from the University of Bonn took this paleontological data and converted it into climate information. Using statistical methods, they matched plant species with statistical parameters regarding temperature and precipitation that determine whether a certain plant can occur. “This allows us to make statements on the probable climate that prevailed during a certain period of time within the catchment area of the Dead Sea,” reports Prof. Dr. Andreas Hense from the University of Bonn’s Meteorological Institute.

The resilience of the resulting climate information was tested using the data on Dead Sea level fluctuations collected by their Israeli colleagues around Prof. Dr. Mordechai Stein from the Geological Services in Jerusalem. “The two independent data records corresponded very closely,” explains Prof. Litt. “In the moist phases that were determined based on pollen analysis, our Israeli colleagues found that water levels were indeed rising in the Dead Sea, while they fell during dry episodes.” This is plausible since the water level of a terminal lake without an outlet is exclusively determined by precipitation and evaporation.

Droughts led to the biblical exodus

According to the Bonn researchers’ data, there were distinct dry phases particularly during the pottery Neolithic (about 7,500 to 6,500 years ago), as well as at the transition from the late Bronze Age to the early Iron Age (about 3,200 years ago). “Humans were also strongly affected by these climate changes,” Prof. Litt summarizes the effects. The dry phases might have resulted in the Canaanites’ urban culture collapsing while nomads invaded their area.
“At least, this is what the Old Testament refers to as the exodus of the Israelites to the Promised Land.”

Dramatic results

In addition, this look back allows developing scenarios for potential future trends. “Our results are dramatic; they indicate how vulnerable the Dead Sea ecosystems are,” says Prof. Litt. “They clearly show how surprisingly fast lush Mediterranean sclerophyll vegetation can morph into steppe or even desert vegetation within a few decades if it becomes drier.” Back then, the consequences in terms of agriculture and feeding the population were most likely devastating. The researchers want to probe even further back into the climate past of the region around the Dead Sea by drilling even deeper.

Why do the Caribbean Islands arc?

This shows USC geophysicists Meghan Miller and Thorsten Becker in Mexico. -  Courtesy of Meghan Miller and Thorsten Becker
This shows USC geophysicists Meghan Miller and Thorsten Becker in Mexico. – Courtesy of Meghan Miller and Thorsten Becker

The Caribbean islands have been pushed east over the last 50 million years, driven by the movement of the Earth’s viscous mantle against the more rooted South American continent, reveals new research by geophysicists from USC.

The results, published today in Nature Geoscience, give us a better understanding of how continents resist the constant movement of the Earth’s plates – and what effect the continental plates have on reshaping the surface of the Earth.

“Studying the deep earth interior provides insights into how the Earth has evolved into its present form,” said Meghan S. Miller, assistant professor of earth sciences in the USC Dornsife College of Letters, Arts and Sciences, and lead author of the paper. “We’re interested in plate tectonics, and the southeastern Caribbean is interesting because it’s right near a complex plate boundary.”

Miller and Thorsten W. Becker, associate professor of earth sciences at USC Dornsife College, studied the margin between the Caribbean plate and the South American plate, ringed by Haiti, the Dominican Republic, Puerto Rico and a crescent of smaller islands including Barbados and St. Lucia.

But just like the First Law of Ecology (and time travel), when it comes to the earth, everything really is connected. So to study the motion of the South American continent and Caribbean plate, the researchers had to first model the entire planet – 176 models to be exact, so large that they took several weeks to compute even at the USC High Performance Computing Center.

For most of us, earthquakes are something to be dreaded. But for Miller and Becker they are a necessary source of data, providing seismic waves that can be tracked all over the world to provide an image of the Earth’s deep interior like a CAT scan. The earthquake waves move slower or more quickly depending on the temperature and composition of the rock, and also depending on how the crystals within the rocks align after millions of years of being pushed around in mantle convection.

“If you can, you want to solve the whole system and then zoom in,” Becker said. “What’s cool about this paper is that we didn’t just run one or two models. We ran a lot, and it allowed us to explore different possibilities for how mantle flow might work.”

Miller and Becker reconstructed the movement of the Earth’s mantle to a depth of almost 3,000 kilometers, upending previous hypotheses of the seismic activity beneath the Caribbean Sea and providing an important new look at the unique tectonic interactions that are causing the Caribbean plate to tear away from South America.

In particular, Miller and Becker point to a part of the South American plate – known as a “cratonic keel” – that is roughly three times thicker than normal lithosphere and much stronger than typical mantle. The keel deflects and channels mantle flow, and provides an important snapshot of the strength of the continents compared to the rest of the Earth’s outer layers.

“Oceanic plates are relatively simple, but if we want to understand how the Earth works as a system – and how faults evolved and where the flow is going over millions of years – we also have to understand continental plates,” Becker said.

In the southeastern Caribbean, the interaction of the subducted plate beneath the Antilles island arc with the stronger continental keel has created the El Pilar-San Sebastian Fault, and the researchers believe a similar series of interactions may have formed the San Andreas Fault.

“We’re studying the Caribbean, but our models are run for the entire globe,” Miller said. “We can look at similar features in Japan, Southern California and the Mediterranean, anywhere we have instruments to record earthquakes.”

Tibetan Plateau may be older than previously thought

The growth of high topography on the Tibetan Plateau in Sichuan, China, began much earlier than previously thought, according to an international team of geologists who looked at mountain ranges along the eastern edge of the plateau.

The Indian tectonic plate began its collision with Asia between 55 and 50 million years ago, but “significant topographic relief existed adjacent to the Sichuan Basin prior to the Indo-Asian collision,” the researchers report online in Nature Geoscience.

“Most researchers have thought that high topography in eastern Tibet developed during the past 10 to 15 million years, as deep crust beneath the central Tibetan Plateau flowed to the plateau margin, thickening the Earth’s crust in this area and causing surface uplift,” said Eric Kirby, associate professor of geoscience, Penn State. “Our study suggests that high topography began to develop as early as 30 million years ago, and perhaps was present even earlier.”

Kirby, working with Erchie Wang, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, and Kevin Furlong, professor of geosciences, Penn State, and colleagues from Waikato University, New Zealand and Arizona State University, looked at samples taken from the hanging wall of the Yingxiu-Beichuan fault, the primary fault responsible for the 2008, Wenchuan earthquake. The researchers used a variety of methods including the decay rate of uranium and thorium to helium in the minerals apatite and zircon and fission track dating, an analysis of tracks or trails left by decaying uranium in minerals again in apatite and zircon.

“These methods allow us to investigate the thermal regime from about 250 degrees Celsius (482 degrees Fahrenheit) to about 60 degrees (140 degrees Fahrenheit),” said Kirby. “The results show that the rocks cooled relatively slowly during the early and mid-Cenozoic — from 30 to 50 million years ago — an indication that topography in the region was undergoing erosion.”

The results also suggest that gradual cooling during this time was followed by two episodes of rapid erosion, one beginning 30 to 25 million years ago and one beginning 15 to 10 million years ago that continues today.

“These results challenge the idea that the topographic relief along the margin of the plateau developed entirely in the Late Miocene, 5 to 10 million years ago,” said Kirby. “The period of rapid erosion between 25 to 30 million years ago could only be sustained if the mountains were not only present, but actively growing, at this time.”

The researchers also note that this implies that fault systems responsible for the 2008 earthquake were also probably active early in the history of the growth of the Tibetan Plateau.

“We are still a long way from completely understanding when and how high topography in Asia developed in response to India-Asia collision,” notes Kirby. “However, these results lend support to the idea that much of what we see today in the mountains of China may have developed earlier than we previously thought.”

Nearly 1,000 earthquakes recorded in Arizona over 3 years

Nearly 60 USArray stations were installed in Arizona from 2006 to 2009 as part of the EarthScope project. Station 118A, seen in this photo, recorded ground motion north of Wilcox in southeastern Arizona from April 6, 2007 to Jan. 21, 2009. -  Incorporated Research Institutions for Seismology (funded by NSF EarthScope)
Nearly 60 USArray stations were installed in Arizona from 2006 to 2009 as part of the EarthScope project. Station 118A, seen in this photo, recorded ground motion north of Wilcox in southeastern Arizona from April 6, 2007 to Jan. 21, 2009. – Incorporated Research Institutions for Seismology (funded by NSF EarthScope)

Earthquakes are among the most destructive and common of geologic phenomena. Several million earthquakes are estimated to occur worldwide each year (the vast majority are too small to feel, but their motions can be measured by arrays of seismometers). Historically, most of Arizona has experienced low levels of recorded seismicity, with infrequent moderate and large earthquakes in the state. Comprehensive analyses of seismicity within Arizona have not been previously possible due to a lack of seismic stations in most regions, contributing to the perception that widespread earthquakes in Arizona are rare. Debunking that myth, a new study published by Arizona State University researchers found nearly 1,000 earthquakes rattling the state over a three-year period.

Jeffrey Lockridge, a graduate student in ASU’s School of Earth and Space Exploration and the project’s lead researcher, used new seismic data collected as part of the EarthScope project to develop methods to detect and locate small-magnitude earthquakes across the entire state of Arizona. EarthScope’s USArray Transportable Array was deployed within Arizona from April 2006 to March 2009 and provided the first opportunity to examine seismicity on a statewide scale. Its increased sensitivity allowed Lockridge to find almost 1,000 earthquakes during the three-year period, including many in regions of Arizona that were previously thought to be seismically inactive.

“It is significant that we found events in areas where none had been detected before, but not necessarily surprising given the fact that many parts of the state had never been sampled by seismometers prior to the deployment of the EarthScope USArray,” says Lockridge. “I expected to find some earthquakes outside of north-central Arizona, where the most and largest events had previously been recorded, just not quite so many in other areas of the state.”

One-thousand earthquakes over three years may sound alarmingly high, but the large number of earthquakes detected in the study is a direct result of the improved volume and quality of seismic data provided by EarthScope. Ninety-one percent of the earthquakes Lockridge detected in Arizona were “microquakes” with a magnitude of 2.0 or smaller, which are not usually felt by humans. Detecting small-magnitude earthquakes is not only important because some regions experiencing small earthquakes may produce larger earthquakes, but also because geologists use small magnitude earthquakes to map otherwise hidden faults beneath the surface.

Historically, the largest earthquakes and the majority of seismicity recorded within Arizona have been located in an area of north-central Arizona. More recently, a pair of magnitude 4.9 and 5.3 earthquakes occurred in the Cataract Creek area outside of Flagstaff. Earthquakes of magnitude 4.0 or larger also have occurred in other areas of the state, including a magnitude 4.2 earthquake in December 2003 in eastern Arizona and a magnitude 4.9 earthquake near Chino Valley in 1976.

“The wealth of data provided by the EarthScope project is an unprecedented opportunity to detect and locate small-magnitude earthquakes in regions where seismic monitoring (i.e. seismic stations) has historically been sparse,” explains Lockridge. “Our study is the first to use EarthScope data to build a regional catalog that detects all earthquakes magnitude 1.2 or larger.”

His results appear in a paper titled, “Seismicity within Arizona during the Deployment of the EarthScope USArray Transportable Array,” published in the August 2012 issue of the Bulletin of the Seismological Society of America. Ramon Arrowsmith and Matt Fouch, professors in ASU’s School of Earth and Space Exploration, are Lockridge’s dissertation advisors and coauthors on the paper. Fouch is also a geophysicist at the Carnegie Institution’s Department of Terrestrial Magnetism in Washington, DC.

“The most surprising result was the degree to which the EarthScope data were able to improve upon existing catalogs generated by regional and national networks. From April 2007 through November 2008, other networks detected only 80 earthquakes within the state, yet over that same time we found 884 earthquakes, or 11 times as many, which is really quite staggering,” says Lockridge. “It’s one of countless examples of how powerful the EarthScope project is and how much it is improving our ability to study Earth.”

Lockridge is also lead author on a study that focuses on a cluster of earthquakes located east of Phoenix, near Theodore Roosevelt Lake. The results from this study will be published in Seismological Research Letters later this year. In his current studies as doctoral student, Lockridge is using the same methods used for Arizona to develop a comprehensive earthquake catalog for the Great Basin region in Nevada and western Utah.

Climate and drought lessons from ancient Egypt

Ancient pollen and charcoal preserved in deeply buried sediments in Egypt’s Nile Delta document the region’s ancient droughts and fires, including a huge drought 4,200 years ago associated with the demise of Egypt’s Old Kingdom, the era known as the pyramid-building time.

“Humans have a long history of having to deal with climate change,” said Christopher Bernhardt, a researcher with the U.S. Geological Survey. “Along with other research, this study geologically reveals that the evolution of societies is sometimes tied to climate variability at all scales – whether decadal or millennial.”

Bernhardt conducted this research as part of his Ph.D. at the University of Pennsylvania, along with Benjamin Horton, an associate professor in Penn’s Department of Earth and Environmental Science. Jean-Daniel Stanley at the Smithsonian Institution also participated in the study, published in July’s edition of Geology.

“Even the mighty builders of the ancient pyramids more than 4,000 years ago fell victim when they were unable to respond to a changing climate,” said USGS Director Marcia McNutt. “This study illustrates that water availability was the climate-change Achilles Heel then for Egypt, as it may well be now, for a planet topping seven billion thirsty people.”

The researchers used pollen and charcoal preserved in a Nile Delta sediment core dating from 7,000 years ago to the present to help resolve the physical mechanisms underlying critical events in ancient Egyptian history.

They wanted to see if changes in pollen assemblages would reflect ancient Egyptian and Middle East droughts recorded in archaeological and historical records. The researchers also examined the presence and amount of charcoal because fire frequency often increases during times of drought, and fires are recorded as charcoal in the geological record. The scientists suspected that the proportion of wetland pollen would decline during times of drought and the amount of charcoal would increase.

And their suspicions were right.

Large decreases in the proportion of wetland pollen and increases in microscopic charcoal occurred in the core during four different times between 3,000 and 6,000 years ago. One of those events was the abrupt and global mega-drought of around 4,200 years ago, a drought that had serious societal repercussions, including famines, and which probably played a role in the end of Egypt’s Old Kingdom and affected other Mediterranean cultures as well.

“Our pollen record appears very sensitive to the decrease in precipitation that occurred in the mega-drought of 4,200 years ago,” Bernhardt said. “The vegetation response lasted much longer compared with other geologic proxy records of this drought, possibly indicating a sustained effect on delta and Nile basin vegetation.”

Similarly, pollen and charcoal evidence recorded two other large droughts: one that occurred some 5,000 to 5,500 years ago and another that occurred around 3,000 years ago.

These events are also recorded in human history – the first one started some 5,000 years ago when the unification of Upper and Lower Egypt occurred and the Uruk Kingdom in modern Iraq collapsed. The second event, some 3,000 years ago, took place in the eastern Mediterranean and is associated with the fall of the Ugarit Kingdom and famines in the Babylonian and Syrian Kingdoms.

“The study geologically demonstrates that when deciphering past climates, pollen and other micro-organisms, such as charcoal, can augment or verify written or archaeological records – or they can serve as the record itself if other information doesn’t exist or is not continuous,” said Horton.

Australia creates world’s first continental-scale mineral maps

The world-first suite of mineral maps details the mineral composition of the surface of the continent. -  CSIRO
The world-first suite of mineral maps details the mineral composition of the surface of the continent. – CSIRO

The world-first maps were generated from a ten-year archive of raw Advanced Spaceborne Thermal Emission and Reflection (ASTER) data collected by NASA and the Japanese Government’s Japan Space Systems.


CSIRO scientists have developed software that transformed the data into a continent-wide suite of mineral maps that show information about rock and soil mineral components and provide a Google-like zoom to view images from thousands of kilometres wide to just a few kilometres. They are already changing the way that geoscientists look for mineral deposits by providing more accurate and detailed information than ever before.

The ASTER maps represent a successful collaboration involving scientists from Japan, USA and Australia. Data access and software development has been coordinated by CSIRO through the Western Australian Centre of Excellence for 3D Mineral Mapping and involves Geoscience Australia, state and territory Geological Surveys, AuScope, iVEC, NCI, JSS, NASA and the USGS.

The maps were officially launched at a short ceremony featuring CSIRO Chief Executive, Dr Megan Clark and Geoscience Australia CEO, Dr Chris Pigram at the 34th International Geological Congress in Brisbane last night.

Following the launch, Professor Yasushi Yamaguchi, head of the Japanese ASTER science team said, “Congratulations on your successful launch of the ASTER geoscience maps of Australia. It is a very good example of the ASTER contribution to the geoscience community and I am very proud of being an ASTER science team member”.

Dr Mike Abrams from NASA and head of the US ASTER science team added, “Congratulations on an impressive project. I do like your idea of producing global geoscience maps, similar to what you have created for Australia”.

The Australian ASTER geoscience maps can be obtained from the AuScope Discovery Portal, the Western Australian Centre of Excellence for 3D Mineral Mapping and Geoscience Australia. State and territory coverage can also be acquired from the respective government geological surveys.

Are methane hydrates dissolving?

The average temperatures of the atmosphere are rising; the average temperatures of the oceans, too. Not only living organisms react sensititvely to these changes. The transitional zones between shallow shelf seas and the deep sea at continental slopes store a huge amount of methane hydrates in the sea bed. These specific, ice-like compounds only forms at low temperatures and under high pressure. When the water temperature directly above the sea bed rises, some of the methane hydrates could dissolve and release the previously bound methane. “This scenario incorporates two fears: Firstly that enormous amounts of this very powerful greenhouse gas will be released into the atmosphere, and secondly that the continental slopes may become unstable” explains the geophysicist Professor Christian Berndt from GEOMAR | Helmholtz Centre for Ocean Research Kiel. He is leading an expedition starting today on the German research vessel MARIA S. MERIAN which will analyse the sea off the western shore of Spitsbergen in order to find out whether the first methane hydrates in the sea bed are dissolving and what the consequences might be.

The expedition builds on research conducted by marine scientists from Kiel who worked in this area of the sea in 2008. Back then they found over 250 places where gas was escaping the sea bed. “These spots lie directly on the border of the area of stable hydrates” explains Professor Berndt. “Therefore we presume that the hydrates are dissolving from the rim inwards.”

During the upcoming expedition, the scientists from Kiel will be working together with colleagues from Bremen, Switzerland, Great Britain and Norway to discover whether the gas emanation shows signs of dissolved hydrates and whether this is due to warmer sea beds.

With the help of echo sounders, researchers will seek out new gas sources in order to determine the total amount of escaping gas. With Germany’s only submersible JAGO, they will closely investigate the gas outlets in up to 400 metres depth. “It is interesting for us, for example, to find out whether special microorganisms that can break down the methane before it is released in the atmosphere have settled around the outlets” explains Professor Tina Treude from GEOMAR, who will be running the microbiological work during the expedition.

Parallel to this, geophysicists, lead by Professor Sebastian Krastel from GEOMAR, will investigate the slopes under the gas outlet spots for signs of instability using acoustic and seismic methods. “The methane hydrates act like binding cement on these slopes. If they dissolve, chances are that parts of the slopes will slide”, explains Professor Krastel, who focuses on marine hazards at GEOMAR.

“Overall the program on this trip is very extensive. Now let us hope that the weather will play along so that we can conduct all planned tests”, says the head of the expedition Christian Berndt shortly before the departure to Iceland.

The expedition at a glance:

FS MARIA S. MERIAN journey: MSM21/4

Chief Scientist: Prof. Dr. Christian Berndt (GEOMAR)

Length of Expedition: 13.08.2012-11.09.2012

Place of Departure: Reykjavik

Research Area: West of Spitsbergen

Place of Arrival: Emden

Further Information on the GEOMAR expedition page under
www.geomar.de/forschen/expeditionen