Early life on Earth may have developed more quickly than thought

The Earth’s climate was far cooler – perhaps more than 50 degrees – billions of years ago, which could mean conditions for life all over the planet were more conducive than previously believed, according to a research team that includes a Texas A&M University expert who specializes in geobiology.

Mike Tice, a researcher in the Department of Geology and Geophysics at Texas A&M, says the findings could change current ideas about the earliest forms of life on Earth. The team includes scientists from Yale University and Stanford University, and their work is published in the current issue of Nature magazine.

Tice says the team examined rocks from the Buck Reef Chert in South Africa that are known to be about 3.4 billion years old, among the oldest ever discovered. They found features in them that are consistent with formation at water temperatures significantly lower than previous studies had suggested.

“Our research shows that the water temperature 3.4 billion years ago was at most 105 degrees, and while that’s potentially very warm, it’s far below the temperatures of 155 degrees or more that previous research has implied,” Tice explains.

The research found that conditions were considerably cooler, probably by 50 degrees or even more. That means that conditions for life were much easier, and that life that did exist at the time was not under as much stress as previously believed.

Tice says the situation could be compared to the geysers currently found in Yellowstone National Park.

The hundreds of hot spring pools in the park vary considerably in temperature, although all of them range from very warm to extremely hot. Water in the pools that is farthest from the center is cooler, and this is shown in the varied colors – from pink to light green, orange and dark green colors, he says.

When water temperatures fall to below 163 degrees or so, close to the high temperatures previously hypothesized for the early ocean, communities of green photosynthetic bacteria begin to grow on the pool floor. These communities become thicker as water temperature continues to drop off away from the pool centers.

“There is life even in the hottest water, and microbes there have evolved to grow in those harsh conditions. But there is even more life present in the cooler waters,” he notes. “We think this is similar to what conditions might have been like billions of years ago.”

Tice says the new findings could open doors for new ways to look at Earth’s early history, especially life forms that existed billions of years ago.

“We know life was around that long ago, but these findings show that the very stressful conditions for life to exist may not have been as stressful as we had thought,” he notes.

“It means more organisms may have been around that were not necessarily heat-loving ones. The findings could give us a better understanding of how life evolved and maybe give us some clues about the long-term history of Earth’s climate and atmosphere.”

How much water does the ocean have?

The calculation of variations in the sea level is relatively simple. It is by far more complicated to then determine the change in the water mass. A team of geodesists and oceanographers from the University of Bonn, as well as from the GFZ German Research Centre for Geosciences and the Alfred-Wegener Institute for Polar and Marine Sciences, two centres of the Helmholtz Association, have now, for the first time succeeded in doing this. The researchers were able to observe short-term fluctuations in the spatial distribution of the ocean water masses. Their results are, amongst others, important for improved climate models.

In order to determine the ocean volume in a certain region, one only needs to know, in addition to the topography of the seabed, the height of the sea level. For this purpose, researchers have long been resorting to gauging stations and satellite altimetric procedures. The ocean mass depends, however, not only on the volume, but also on the temperature and on the salt content. Water expands when heated. Warm water, thus, weighs less than the same quantity of cold water.

For the calculation of the ocean mass it is, therefore, necessary to know the temperature and salt content profiles. However, this is not easy to quantify. “For our study we, therefore, combined different procedures so as to be able to judge changes in mass”, explains Professor Dr. Juergen Kusche. The geodesist from Bonn is co-author of a scientific paper, which has just been published in the Journal of Geophysical Research.

On the one hand the researchers used data from the German-American satellite mission GRACE where the distance between two satellites (popularly known as Tom and Jerry as one chases the other in the same orbit ) are measured exactly to thousandths of millimetres. The larger the ocean mass at a certain point of the Earth, the stronger the gravitational strength. This influences the flight altitude of the satellites and thus the distance from each other. The gravitation and, hence, the mass distribution can be calculated from the change in distance between the two satellites.

The seabed bends under the weight of the water

In addition, the scientists put to use an effect which frequent book readers will have perceived. The ocean floor bends similarly to that of the shelves of an overfilled bookshelf. Thus, stationary GPS-gauging stations on land drop by up to one centimetre and move closer by a few millimetres. The heavier the water, the stronger is this movement.

“We combined these data with numerical models of the ocean” explains Kusche. “In this way we were able to prove, for the first time, that in particular in the higher latitudes, significant fluctuations of the water mass occur, and that this takes place within a time period of only one to two weeks”.

So far one only knew that the mass of the world-wide ocean water varies seasonally by on average approximately three quadrillion kilogrammes (a quadrillion equals to 1 followed by 15 zeroes) – that implies a sea level variation of approx. seven to eight millimetres. This effect is brought about, among others, by variations in precipitation and evaporation as well as by the storage of water as snow. But, also, the melting of the glaciers and the ice masses in Greenland and in the Antarctic play a role.


By comparing the variation in volume and in mass the researchers want to determine changes in the amount of heat stored in the ocean. Therefore, in the near future, the long term changes are to be examined. The results will contribute to improved climatic models.

An urgent wish of the scientists is the realisation of a punctual follow-up mission for the satellite tandem GRACE. Otherwise the valuable information, particular in the registration of trends in the Earth system, obtained through GRACE, cannot be used to its full potential for Earth System and climate research.

Underground mine ventilation subject of study

Kray Luxbacher of the Virginia Tech mining and minerals engineering department has received a $1.24 million, five-year contract to study the effects of roof falls, bumps, or explosions on underground mine ventilation systems. Phase 1 will consist of developing project tools, such as a computer program which will allow multiple users to employ computational fluid dynamics modeling, and an experimental apparatus for testing tracer gases. -  Virginia Tech Photo
Kray Luxbacher of the Virginia Tech mining and minerals engineering department has received a $1.24 million, five-year contract to study the effects of roof falls, bumps, or explosions on underground mine ventilation systems. Phase 1 will consist of developing project tools, such as a computer program which will allow multiple users to employ computational fluid dynamics modeling, and an experimental apparatus for testing tracer gases. – Virginia Tech Photo

The Virginia Tech mining and minerals engineering department has received a $1.24 million, five-year contract by the National Institute for Occupational Safety and Health (NIOSH) to study the effects of roof falls, bumps, or explosions on underground mine ventilation systems.

Kray Luxbacher, an assistant professor with the College of Engineering’s mining department (http://www.mining.vt.edu/), is serving as principal investigator of the study. She will be supported by fellow faculty members Saad Ragab, a professor in the department of engineering sciences and mechanics, and Robert Boggess, research associate, and Harold McNair, professor emeritus of chemistry in the College of Science‘s department of chemistry. They bring expertise in gas chromatography and computational fluid mechanics to this interdisciplinary project.

Titled “Development of a Method for the Remote Characterization of Underground Mine Ventilation Controls by Multiple Tracer Gases,” the project will use gas tracers as a means of remotely ascertaining information about ventilation control systems following a mine collapse or explosion.

“This project has the potential to provide insight into the status of a mine ventilation system following a serious incident, when information is limited and decisions impacting the safety of mine rescue personnel and miners must be made,” said Luxbacher.

Utilizing scaled models and real working mines, the study will allow for the rapid collection tracer gas profiles under normal operating conditions, as well as a simulated emergency, in an underground coal mine. It is hope that the new process, using computational fluid mechanics, can determine the state of ventilation controls, including the nature and general location of damage, by comparing collected and simulated tracer gas profiles.

The grant will allocate $250,000 each year for five years. Phase 1 will consist of developing project tools, such as a computer program which will allow multiple users to employ computational fluid dynamics modeling, and an experimental apparatus for testing tracer gases. Additionally, a tracer gas other than sulfur hexafluoride — the industry standard in such mine ventilation tests – will be identified and tested in both the laboratory and field. Additional gases allow complex mine ventilation systems to be evaluated more quickly, Luxbacher said.

This NIOSH grant is designed to increase mine ventilation expertise thorough graduate education and to develop technologies that improve mine safety and health. “The average age of people employed in the mining industry is fairly high, and the exodus of experienced personnel is affecting research and higher education,” Luxbacher said. “This grant is a proactive step by NIOSH to increase expertise in mine ventilation, which is key to maintaining safe mines and advancing mine safety and health.”

A glimpse at the Earth’s crust deep below the Atlantic

TOBI sidescan sonar imagery draped over multibeam bathymetry provides a unique 3-D view of an active oceanic core complex at 13°19'N, the Mid-Atlantic Ridge. The core complex is the smooth, striated dome forming the left-hand side of the image. To its right is the hummocky neovolcanic zone where recent volcanoes erupt lavas forming the the new oceanic crust. The field of view is around 30km wide. -  NOCS
TOBI sidescan sonar imagery draped over multibeam bathymetry provides a unique 3-D view of an active oceanic core complex at 13°19’N, the Mid-Atlantic Ridge. The core complex is the smooth, striated dome forming the left-hand side of the image. To its right is the hummocky neovolcanic zone where recent volcanoes erupt lavas forming the the new oceanic crust. The field of view is around 30km wide. – NOCS

Long-term variations in volcanism help explain the birth, evolution and death of striking geological features called oceanic core complexes on the ocean floor, says geologist Dr Bram Murton of the National Oceanography Centre, Southampton.

Oceanic core complexes are associated with faults along slow-spreading mid-ocean ridges. They are large elevated massifs with flat or gently curved upper surfaces and prominent corrugations called ‘megamullions’. Uplifting during their formation causes exposure of lower crust and mantle rocks on the seafloor.

Murton was member of a scientific team that in 2007 sailed to the mid Atlantic Ridge aboard the royal research ship RRS James Cook to study the Earth’s crust below the ocean.

“We wanted to know why some faults develop into core complexes, whereas others don’t,” he says: “It had been suggested that core complexes form during periods of reduced magma supply from volcanism, but exactly how this would interact with the tectonic forces that deform the Earth’s crust was unclear.”

Using the deep-towed vehicle TOBI equipped with sophisticated sonar equipment for profiling the deep seafloor, Murton and his colleagues discovered three domed and corrugated massifs, from which they dredged and drilled rock samples.

“These massifs turned out to be oceanic core complexes at different stages of a common life cycle,” says Murton: “By comparing them we are able to get a much better understanding of the birth, evolution and death of these fascinating geological features.”

It turns out that there is indeed a close link between core complex formation and long-term variations in magma supply. “Core complex development may take a million years or so and is associated with suppressed or absent volcanism,” says Murton.

Faults that initiate core complex formation start off pretty much like normal faults around them. But in the absence of sufficient magma, the two sides of the fault continue to slip, and this slippage is further lubricated by seawater penetration and talc formation along the fault zones, leading to deep and large off-set faulting.

However, renewed volcanism can increase the supply of magma, overwhelming the fault. “We believe that renewed or increased volcanism is what eventually terminates the process of core complex formation.” says Murton.

Controversial new climate change data

Like all studies of this kind, there are uncertainties in the data, so rather than relying on Nature to provide a free service, soaking up our waste carbon, we need to ascertain why the proportion being absorbed has not changed.
Like all studies of this kind, there are uncertainties in the data, so rather than relying on Nature to provide a free service, soaking up our waste carbon, we need to ascertain why the proportion being absorbed has not changed.

New data show that the balance between the airborne and the absorbed fraction of CO2 has stayed approximately constant since 1850, despite emissions of CO2 having risen from about 2 billion tons a year in 1850 to 35 billion tons a year now.

This suggests that terrestrial ecosystems and the oceans have a much greater capacity to absorb CO2 than had been previously expected.

The results run contrary to a significant body of recent research which expects that the capacity of terrestrial ecosystems and the oceans to absorb CO2 should start to diminish as CO2 emissions increase, letting greenhouse gas levels skyrocket. Dr Wolfgang Knorr at the University of Bristol, UK, found that in fact the trend in the airborne fraction since 1850 has only been 0.7 ± 1.4% per decade, which is essentially zero.

The strength of the new study, published online in Geophysical Research Letters, is that it rests solely on measurements and statistical data, including historical records extracted from Antarctic ice, and does not rely on computations with complex climate models.

This work is extremely important for climate change policy, because emission targets to be negotiated at the United Nations Climate Change Conference in Copenhagen early next month have been based on projections that have a carbon free sink of already factored in. Some researchers have cautioned against this approach, pointing at evidence that suggests the sink has already started to decrease.

So is this good news for climate negotiations in Copenhagen? “Not necessarily”, says Knorr. “Like all studies of this kind, there are uncertainties in the data, so rather than relying on Nature to provide a free service, soaking up our waste carbon, we need to ascertain why the proportion being absorbed has not changed”.

Another result of the study is that emissions from deforestation might have been overestimated by between 18 and 75 per cent. This would agree with results published last week in Nature Geoscience by a team led by Guido van der Werf from VU University Amsterdam. They re-visited deforestation data and concluded that emissions have been overestimated by at least a factor of two.

Scientist develops lab machine to study glacial sliding related to rising sea levels

Neal Iverson, an Iowa State professor of geological and atmospheric sciences, worked with a team of Ames Laboratory engineers to develop a machine that can simulate how glaciers slide across their beds. At the bottom of the machine is a hydraulic press that can create pressures equal to those beneath a glacier 1,300 feet thick. -  Photo by Bob Elbert/Iowa State University.
Neal Iverson, an Iowa State professor of geological and atmospheric sciences, worked with a team of Ames Laboratory engineers to develop a machine that can simulate how glaciers slide across their beds. At the bottom of the machine is a hydraulic press that can create pressures equal to those beneath a glacier 1,300 feet thick. – Photo by Bob Elbert/Iowa State University.

Iowa State scientist develops lab machine to study glacial sliding related to rising sea levels


AMES, Iowa – Neal Iverson opened his laboratory’s walk-in freezer and said the one-of-a-kind machine inside could help scientists understand how glaciers slide across their beds. And that could help researchers predict how glaciers will react to climate change and contribute to rising sea levels.

Iverson is an Iowa State University professor of geological and atmospheric sciences. He’s worked for three years on his big new machine, which is over nine feet tall, that he calls a glacier sliding simulator.

At the center of the machine is a ring of ice about eight inches thick and about three feet across. Below the ice is a hydraulic press that can put as much as 170 tons of force on the ice, creating pressures equal to those beneath a glacier 1,300 feet thick. Above are motors that can rotate the ice ring at its centerline at speeds of 100 to 7,000 feet per year. Either the speed of the ice or the stress dragging it forward can be controlled. Around the ice is circulating fluid – its temperature controlled to 1/100th of a degree Celsius – that keeps the ice at its melting point so it slides on a thin film of water.

As Iverson starts running experiments with the simulator this month, he’ll be looking for data that help explain glacier movement.

“For a particular stress, which depends on a glacier’s size and shape, we’d like to know how fast a glacier will slide,” Iverson said.

Glacier sliding is something that matters far from the ice fields. As the climate warms, Iverson said glaciers slide faster. When they hit coasts, they dump ice into the ocean. And when those icebergs melt they contribute to rising sea levels.

But there’s a lot about the process researchers still don’t know.

“We can’t predict how fast glaciers slide – even to a factor of 10,” Iverson said. “We don’t know enough about how they slide to do that.”

And so Iverson came up with the idea of a glacier in a freezer that allows him to isolate effects of stress, temperature and melt-water on speeds of glacier sliding.

The project is supported by a $529,922 grant from the National Science Foundation. While Iverson had a rough design for the simulator, he said a team of three engineers from the U.S. Department of Energy’s Ames Laboratory – Terry Herrman, Dan Jones and Jerry Musselman – improved the design and turned it into a working machine.

Iverson said the machine won’t simulate everything about glacier sliding.

“The fact is we can’t simulate the real process,” he said. “We can only simulate key elements of the process. The purpose of these experiments will be to idealize how the system works and thereby learn fundamentals of the sliding process that can’t be learned in the field because of the complexity there.”

Iverson, who also does field studies at glaciers in Sweden and Norway, said glaciology needs work on the ground and in the lab. But it’s been decades since anybody has attempted the kind of laboratory simulations he’ll be doing.

“There hasn’t been a device to do this,” Iverson said. “And so there haven’t been any experiments.”

To change that, Iverson is pulling on a coat, hat and gloves and working in his lab’s freezer. He has ice rings to build. Equipment to calibrate. And experiments to run.

Cave study links climate change to California droughts

California experienced centuries-long droughts in the past 20,000 years that coincided with the thawing of ice caps in the Arctic, according to a new study by UC Davis doctoral student Jessica Oster and geology professor Isabel Montañez.

The finding, which comes from analyzing stalagmites from Moaning Cavern in the central Sierra Nevada, was published online Nov. 5 in the journal Earth and Planetary Science Letters.

The sometimes spectacular mineral formations in caves such as Moaning Cavern and Black Chasm build up over centuries as water drips from the cave roof. Those drops of water pick up trace chemicals in their path through air, soil and rocks, and deposit the chemicals in the stalagmite.

“They’re like tree rings made out of rock,” Montañez said. “These are the only climate records of this type for California for this period when past global warming was occurring.”

At the end of the last ice age about 15,000 years ago, climate records from Greenland show a warm period called the Bolling-Allerod period. Oster and Montanez’s results show that at the same time, California became much drier. Episodes of relative cooling in the Arctic records, including the Younger Dryas period 13,000 years ago, were accompanied by wetter periods in California.

The researchers don’t know exactly what connects Arctic temperatures to precipitation over California. However, climate models developed by others suggest that when Arctic sea ice disappears, the jet stream — high-altitude winds with a profound influence on climate — shifts north, moving precipitation away from California.

“If there is a connection to Arctic sea ice then there are big implications for us in California,” Montañez said. Arctic sea ice has declined by about 3 percent a year over the past three decades, and some forecasts predict an ice-free Arctic ocean as soon as 2020.

Oster’s analysis of the past is rooted in a thorough understanding of the cave in the present. Working with the cave owners, she has measured drip rates, collected air, water, soil and vegetation samples, and studied what happens to the cave through wet and dry seasons to determine how stalagmites are affected by changing conditions.

Oster collected stalagmites and cut tiny samples from them for analysis. The ratio of uranium to its breakdown product, thorium, allowed her to date the layers within the stalagmite. Isotopes of oxygen, carbon and strontium and levels of metals in the cave minerals all vary as the climate gets wetter or drier.

“Most respond to precipitation in some way,” Oster said. For example, carbon isotopes reflect the amount of vegetation on the ground over the cave. Other minerals tend to decrease when rainfall is high and water moves through the aquifer more rapidly.

Oxygen-18 isotopes vary with both temperature and rainfall. Measuring the other mineral compositions provides more certainty that the changes primarily track relative rainfall.

The stalagmite records allowed Oster and Montañez to follow relative changes in precipitation in the western Sierra Nevada with a resolution of less than a century.

“We can’t quantify precipitation, but we can see a relative shift from wetter to drier conditions with each episode of warming in the northern polar region,” Montañez said.

Earth’s early ocean cooled more than a billion years earlier than thought

Green and orange photosynthetic microbial mats line an outflow channel from a hot spring in Yellowstone National Park. These thin mats grow only where the downstream water temperature falls below 73 C. The mats become thicker and more complex as the temperature drops. Stanford researchers found evidence for cooler waters in the ancient global ocean that would have allowed photosynthetic life to spread far beyond such narrow confines. -  Michael Tice, Texas A&M University
Green and orange photosynthetic microbial mats line an outflow channel from a hot spring in Yellowstone National Park. These thin mats grow only where the downstream water temperature falls below 73 C. The mats become thicker and more complex as the temperature drops. Stanford researchers found evidence for cooler waters in the ancient global ocean that would have allowed photosynthetic life to spread far beyond such narrow confines. – Michael Tice, Texas A&M University

The scalding-hot sea that supposedly covered the early Earth may in fact never have existed, according to a new study by Stanford University researchers who analyzed isotope ratios in 3.4 billion-year-old ocean floor rocks. Their findings suggest that the early ocean was much more temperate and that, as a result, life likely diversified and spread across the globe much sooner in Earth’s history than has been generally theorized.

It also means that the chemical composition of the ancient ocean was significantly different from today’s ocean, which in turn may change interpretations of how the early atmosphere evolved, said Page Chamberlain, professor of environmental earth system science.

When rocks form on the ocean floor, they form in chemical equilibrium with the ocean water, incorporating similar proportions of different isotopes into the rock as are in the water. Isotopes are atoms of the same element that have different numbers of neutrons in the nucleus, giving them different masses. However, because the exact proportion of different isotopes that go into the rock is partly temperature dependent, the ratios in the rock provide critical clues into how warm the ocean was when the rock formed.

Previous studies of similarly aged rocks had looked only at oxygen isotope ratios, which suggested that in the Archean era (about 3.5 billion years ago), the ocean temperature was at least 55 degrees Celsius and may have been as high as 85 C, or 185 F. At a water temperature so perilously close to the boiling point, the only organisms that could have thrived would have been extremophiles – life forms adapted to extreme environments – such as the microbes that live in the intense heat of deep-sea hydrothermal vents or in hot springs such as at Yellowstone National Park.

But isotope ratios recorded in rocks on the ocean floor are also dependent on the chemical composition of the seawater in which those rocks formed, and the past studies assumed the composition of the ancient ocean was essentially what it is today, which the Stanford study did not.

Using a relatively new approach, Michael Hren and Mike Tice, both Stanford graduate students at the time, analyzed hydrogen isotopes as well as oxygen isotopes in chert, a type of fine-grained sedimentary rock consisting primarily of quartz. The chert they studied was from an ancient deposit, formerly underwater but now on dry land in South Africa.

From a cauldron to a nice warm bath

“By looking at both oxygen and hydrogen in these ancient rocks we were able to put some constraints on how different the ancient ocean composition may have been from today, and then use that composition to try to determine how hot the ancient ocean was,” said Hren, who is the lead author of a paper describing the work being published online Nov. 12 by Nature. Tice and Chamberlain are coauthors.

Having data from isotope ratios of two elements allowed the researchers to calculate upper and lower bounds for the range of temperature and composition that could have given rise to the observed ratios. They determined that the ocean temperature could not have been more than 40 C (104 F) – the temperature of a hot tub – and may have been lower in some parts.

“This means that by 3.4 billion years ago, there were at least some places on the surface of the Earth where organisms that could not survive in these hot hydrothermal conditions could exist and thrive,” Hren said. “It also suggests that the chemical composition of the ancient ocean was probably not identical to today, as previous studies assumed. It may have been quite different.”

The researchers found that the ratio of the two stable isotopes of hydrogen in the chert was tilted away from the heavier of the isotopes – called deuterium.

“The ancient ocean had a lot more hydrogen in it, relative to deuterium, than modern oceans,” Chamberlain said.

If the composition of the Archean ocean was significantly different from today, then the atmosphere must have been markedly different, too, owing to the ease with which gases move across the air-water boundary as the ocean and lower atmosphere strive to stay in a rough equilibrium.

That means that sometime during the past 3.4 billion years, the ocean had to lose a lot of hydrogen to the atmosphere to bring the hydrogen isotope ratio in seawater to where it is today. And since oxygen, not hydrogen, has built up in Earth’s atmosphere over that same period of time, the atmosphere must have discharged a lot of hydrogen to the only other place it could go: space.

Hren said that some recent models of the early Earth atmosphere suggest that there may have been a prolonged period of hydrogen escaping to space, which would be consistent with the Stanford team’s findings.

Little land, but happy lives on the early Earth

The chemical composition of air and water weren’t the only things different about Earth during the Archean era.

“We are talking about a time when, if you were looking at the Earth from space, you would hardly see any land mass at all,” Tice said. “It would have almost been an ocean world.”

The chert samples came from a formation called the Buck Reef Chert, which covered a broad area from shallow to deep marine environments. Some of the chert was probably deposited on the slopes of a volcanic island, similar to those in the Hawaiian Islands, that had gone extinct, cooled, eroded and slowly subsided under the sea, he said.

Tice collected the chert samples from South Africa several years ago while he was a graduate student with Don Lowe, professor of geological and environmental sciences. In 2004, Lowe and Tice described a fossil microbial ecosystem preserved in some of the chert that was deposited on a shallow submerged platform, which they deduced was photosynthetic. Tice said the temperature setting was probably somewhat comparable to a modern day tidal flat, where similar photosynthetic microbial mats flourish today, although the depth of the Archean setting was similar to continental shelves of today.

“At the higher temperatures that were hypothesized earlier, those organisms could have survived but they would have had a harder time,” he said. “At the temperatures we are suggesting, they would have been completely comfortable. They would have been happy.

“And that is significant because photosynthetic organisms, even bacteria, form the base of essentially every modern food chain,” Tice added.

Checking the chert

With major ramifications for the ocean, atmosphere and nature of life on the early Earth coming out of their study, the researchers know their work is likely to receive some scrutiny.

“Anytime you are dealing with something that has been on Earth for 3.4 billion years, it is always going to be a question of whether these are pristine or not,” Chamberlain said.

But the cherts the Stanford team worked with “are particularly good rocks,” he said, “because they have not been stuck deep in the Earth, crushed and heated, and so they preserve something of what the original oceans were like.”

Still, to rule out any alteration of the rocks, Hren said they did calculations to see what would happen if the chert had been subjected to later hydrothermal water flowing through it, or other post-depositional processes that could potentially alter the chemistry of the samples.

“We can show some of the data has been altered by later fluids, but some of it is recording this original ocean composition and temperature data,” he said. “So by looking at these two separate trends, we can see which data reflects this original formation.

“I think it is really giving us a better idea of these conditions at a very early time in the Earth’s history,” Hren said.


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Stanford researchers blasted ancient ocean floor rocks with lasers to boil out the isotopes that provided critical clues about the temperature of the ancient ocean.

The early global sea turns out to have been tepid, not a hot primordial soup as had been thought. – Jack Hubbard, Stanford University News Service

Central Africa’s tropical Congo Basin was arid, treeless in Late Jurassic

The Congo Basin – with its massive, lush tropical rain forest – was far different 150 million to 200 million years ago. At that time Africa and South America were part of the single continent Gondwana. The Congo Basin was arid, with a small amount of seasonal rainfall, and few bushes or trees populated the landscape, according to a new geochemical analysis of rare ancient soils.

The geochemical analysis provides new data for the Jurassic period, when very little is known about Central Africa’s paleoclimate, says Timothy S. Myers, a paleontology doctoral student in the Roy M. Huffington Department of Earth Sciences at Southern Methodist University in Dallas.

“There aren’t a whole lot of terrestrial deposits from that time period preserved in Central Africa,” Myers says. “Scientists have been looking at Africa’s paleoclimate for some time, but data from this time period is unique.”

There are several reasons for the scarcity of deposits: Ongoing armed conflict makes it difficult and challenging to retrieve them; and the thick vegetation, a humid climate and continual erosion prevent the preservation of ancient deposits, which would safeguard clues to Africa’s paleoclimate.

Myers’ research is based on a core sample drilled by a syndicate interested in the oil and mineral deposits in the Congo Basin. Myers accessed the sample – drilled from a depth of more than 2 kilometers – from the Royal Museum for Central Africa in Tervuren, Belgium, where it is housed. With the permission of the museum, he analyzed pieces of the core at the SMU Huffington Department of Earth Sciences Isotope Laboratory.

“I would love to look at an outcrop in the Congo,” Myers says, “but I was happy to be able to do this.”

The Samba borehole, as it’s known, was drilled near the center of the Congo Basin. The Congo Basin today is a closed canopy tropical forest – the world’s second largest after the Amazon. It’s home to elephants, great apes, many species of birds and mammals, as well as the Congo River. Myers’ results are consistent with data from other low paleolatitude, continental, Upper Jurassic deposits in Africa and with regional projections of paleoclimate generated by general circulation models, he says.

“It provides a good context for the vertebrate fossils found in Central Africa,” Myers says. “At times, any indications of the paleoclimate are listed as an afterthought, because climate is more abstract. But it’s important because it yields data about the ecological conditions. Climate determines the plant communities, and not just how many, but also the diversity of plants.”

While there was no evidence of terrestrial vertebrates in the deposits that Myers studied, dinosaurs were present in Africa at the same time. Their fossils appear in places that were once closer to the coast, he says, and probably wetter and more hospitable.

The Belgium samples yielded good evidence of the paleoclimate. Myers found minerals indicative of an extremely arid climate typical of a marshy, saline environment. With the Congo Basin at the center of Gondwana, humid marine air from the coasts would have lost much of its moisture content by the time it reached the interior of the massive continent.

“There probably wouldn’t have been a whole lot of trees; more scrubby kinds of plants,” Myers says.

The clay minerals that form in soils have an isotopic composition related to that of the local rainfall and shallow groundwater. The difference in isotopic composition between these waters and the clay minerals is a function of surface temperature, he says. By measuring the oxygen and hydrogen isotopic values of the clays in the soils, researchers can estimate the temperature at which the clays formed. For more information see www.smuresearch.com.

Deep creep means milder, more frequent earthquakes along Southern California’s San Jacinto fault

<IMG SRC="/Images/983893990.jpg" WIDTH="350" HEIGHT="293" BORDER="0" ALT="A University of Miami study by Dr. Shimon Wdowinski in Nature Geosciences demonstrates that deep creep means milder, more frequent earthquakes along SoCal’s San Jacinto fault make it a less likely candidate for a major earthquake than its neighbor to the east, the Southern San Andreas fault. – UM/RSMAS”>
A University of Miami study by Dr. Shimon Wdowinski in Nature Geosciences demonstrates that deep creep means milder, more frequent earthquakes along SoCal’s San Jacinto fault make it a less likely candidate for a major earthquake than its neighbor to the east, the Southern San Andreas fault. – UM/RSMAS

With an average of four mini-earthquakes per day, Southern California’s San Jacinto fault constantly adjusts to make it a less likely candidate for a major earthquake than its quiet neighbor to the east, the Southern San Andreas fault, according to an article in the journal Nature Geoscience.

“Those minor to moderate events along the San Jacinto fault relieve some of the stress built by the constantly moving tectonic plates,” said Shimon Wdowinski, research associate professor at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.

Previous estimates may have overstated the likelihood of a major event on the 140-mile long San Jacinto fault, which begins between Palm Springs and Los Angeles and runs south toward the Salton Sea east of San Diego. The US Geological Survey (USGS) is forecasting a 31 percent chance that an earthquake with a magnitude of 6.7 or higher on the Richter Scale will occur on the San Jacinto fault in the next 30 years. Only the San Andreas fault, with a 59 percent chance, is more likely to have a major event during the same period.

“Thirty-one percent is a high probability, when it comes to earthquake forecasting-the second highest in Southern California,” said Wdowinski. “Our data show that the next significant event for the San Jacinto fault would probably be between 6.0 and 6.7. It doesn’t sound like much, but in earthquake terms it is the difference between a major earthquake and a moderate event.”

A magnitude 6.0 earthquake may be felt for dozens of miles from the epicenter, but building damage especially in California, due to strict building codes, would be minimal. As the magnitude approaches and passes 7.0, which is ten times stronger than an earthquake with a magnitude of 6.0, more serious property damage and loss of life may occur.

Wdowinski feels that the San Jacinto fault is not as dangerous as predicted, because “deep creep” releases elastic strain of the moving plates approximately six to ten miles beneath the surface. As a result, the accumulation of strain along the fault occurs in the upper six miles of crust, which may be released by more frequent, moderate earthquakes. However a major event can still occur on the San Jacinto fault, but with lower probability, if two segments of the fault rupture simultaneously.

By contrast, the more famous Southern San Andreas fault to the east is locked some 10 miles down, throughout the entire seizmogenic crust. It has had very few earthquakes to release that strain but promises to release much more energy-a major earthquake-when a rupture occurs.

“It’s like bending a stick,” said Wdowinski. “You can bend it until it breaks and releases the energy. The San Jacinto fault [on the left in the figure below] is like a stick that has a cut in it. When you begin bending it and it breaks, less energy is released. Deep creep-evidenced by those small, more frequent earthquakes-in effect forms that small cut that reduces the release of energy when the rupture finally occurs. We are less likely to have the big energy release of a major earthquake because the energy is not allowed to build up.”

The Southern San Andreas fault to the east is like a thicker stick without any stress-relieving cuts, which will snap with much greater force. USGS predicts that the San Andreas fault has a 59 percent chance of a major earthquake (greater than a magnitude of 6.7) in the next 30 years.

Aside from earthquakes, Wdowinski’s primary research interest at the University of Miami is hydrology and water flow in wetlands and the Florida Everglades, in particular. The link between desert earthquakes and swamps is geodesy, the study of the earth’s size, shape, orientation, gravitational field, and their variations over time. He uses satellite imaging and the Global Positioning System (GPS) to measure those slight changes.

“These are the new tools of geodesy,” said Wdowinski, who co-authored a May 2009 paper in the journal Eos, Transactions, a publication of the American Geophysical Union. The article highlighted “Geodesy in the 21st Century”, a look at how technological advances are benefiting the field and are applicable to many important societal issues, such as climate change, natural hazards, and water resources.