Scientists discover Amazon river is 11 million years old

Researchers at the University of Liverpool have discovered that the Amazon river, and its transcontinental drainage, is around 11 million years old and took its present shape about 2.4 million years ago.

University of Liverpool researchers, in collaboration with the University of Amsterdam and Petrobras, the national oil company of Brazil, analysed sedimentary material taken from two boreholes near the mouth of the river to calculate the age of the Amazon river and the Amazon deep sea fan.

Prior to this study the exact age of the Amazon, one of the two largest rivers in the world, was not known. Until recently the Amazon Fan, a submarine sediment column around 10km thick, had proven difficult to penetrate. New exploration efforts by Petrobas, however, have lea to two new boreholes being drilled near the mouth of the Amazon – one 2.5miles (4.5km) below sea level – which resulted in new sedimentological and paleontological analysis of samples from the river sediment.

“River sediment records provide a unique insight into the palaeoclimate and geography of the hinterland,” said Jorge Figueiredo from the University’s Department of Earth and Ocean Sciences

“This new research has large implications for our understanding of South American paleogeography and the evolution of aquatic organisms in Amazonia and on the Atlantic coast. The origin of the Amazon river is a defining moment: a new ecosystem came into being at the same time as the uplifting Andes formed a geographic divide.”

The study was published in the scientific journal, Geology, in July 2009.

Study sheds light on earthquake hazard along San Andreas Fault

Scripps researchers deploy the CHIRP image profiler. -  Scripps Institution of Oceanography, UC San Diego
Scripps researchers deploy the CHIRP image profiler. – Scripps Institution of Oceanography, UC San Diego

New research by a team of scientists from Scripps Institution of Oceanography at UC San Diego and the U.S. Geological Survey (USGS) offers new insight into the San Andreas Fault as it extends beneath Southern California’s Salton Sea. The team discovered a series of prominent faults beneath the sea, which transfer motion away from the San Andreas Fault as it disappears beneath the Salton Sea. The study provides new understanding of the intricate earthquake faults system beneath the sea and what role it may play in the earthquake cycle along the southern San Andreas Fault.

“The stretch of the San Andreas Fault that extends into the Salton Sea is an important part of the overall fault system but it remains poorly understood,” said Danny Brothers, a Scripps graduate student and lead author on the study. “Our results provide crucial information on how deformation is transferred from the San Andreas Fault to the Imperial Fault and how young basins along strike-slip faults, such as the Salton Sea, evolve through time.”

In a study published in the July 26 early online edition of the journal Nature Geoscience, the Scripps-led research team including Brothers, Neal Driscoll, Graham Kent, Alistair Harding, Jeff Babcock and Rob Baskin, from the USGS, used geophysical methods to image the faults beneath the Salton Sea. This study offers new information on the location of faults and how they communicate tectonic deformation with neighboring faults located onshore.

The Salton Sea is flanked by two major faults – the San Andreas and San Jacinto – and recent studies have revealed that the region has experienced magnitude-7 earthquakes roughly every 200 years for the last thousand years. Previous studies conducted by researchers at San Diego State University and Cal Tech indicate that it has been approximately 300 years since the last rupture.

“We discovered a series of prominent faults near Bombay Beach during pilot studies in 2006 and 2007, and went on to survey the area more comprehensively in 2008 and 2009,” researchers stated in the journal’s “backstory” commentary section. The highlight of the expedition was when the team discovered the first previously unknown fault in the Salton Sea, just miles offshore from Bombay Beach, Calif.

The research team used a high-resolution seismic imaging technique, known as CHIRP, to image the layers of sediments beneath the lake that have been offset by the motion of faults. Scripps’ Neal Driscoll developed the digital CHIRP profiler to provide high-quality imagery of the sediments below oceans and lakes to offer a comprehensive view of underwater faults.

Mines could provide geothermal energy

Village that could benefit from geotermic energy. -  Rodríguez et al. / SINC
Village that could benefit from geotermic energy. – Rodríguez et al. / SINC

Mine shafts on the point of being closed down could be used to provide geothermal energy to local towns. This is the conclusion of two engineers from the University of Oviedo, whose research is being published this month in the journal Renewable Energy. The method they have developed makes it possible to estimate the amount of heat that a tunnel could potentially provide.

“One way of making use of low-intensity geothermal energy is to convert mine shafts into geothermal boilers, which could provide heating and hot water for people living nearby”, Rafael Rodríguez, from the Oviedo Higher Technical School of Mining Engineering, tells SINC. This type of energy, which is hardly used in Spain, is obtained from the internal heat of the Earth.

The engineer and his colleague María Belarmina Díaz have developed a “semi-empirical” method (part mathematical and part experimental) to calculate the amount of heat that could be produced by a mine tunnel that is due to be abandoned, based on studies carried out while it is still in use.

“When the mine is still active one can access the tunnels easily in order to gather data about ventilation and the properties of the rocks, as well as to take samples and design better circuits, and even programme the closure of some sections in order to use them for geothermal energy production”, says the engineer, who stresses that, although geothermal energy can be made use of once the mine is closed, “it is no longer possible by that stage to make any modifications, or to gather any useful data to evaluate and improve the system”.

The study looks into geothermal exploitation of a two-kilometre-long mine shaft, in which the temperature of the rocks 500m below the surface is around 30º C. This is typical of many of the mining areas in Asturias, although it could also be applied to other parts of the world. Water could be forced in through tubes at 7º C and return at 12º C, a big enough heat gain to be of benefit to towns located above the mines.

Advantages of geothermal energy from mines

Rodríguez and Díaz highlight the benefits of building geothermal boilers in mine shafts in that, aside from their predictable energy production levels, they also function practically as an open tube system “but without any risk of heat contamination of aquifers”.

Using geothermal energy also helps to reduce CO2 emissions, and is not dependent upon climatic conditions (unlike other renewable energies such as solar or wind power). Other advantages are that these facilities make use of a country’s own resources, do not require new developments on large sites, do not pollute the immediate environment, and are believed to be profitable over the long term.

Geothermal energy can be used directly in family homes, housing developments, swimming pools, fish farms, industrial units and other buildings.

Hydrocarbons in the deep Earth?

This artistic view of the Earth's interior shows hydrocarbons forming in the upper mantle and transported through deep faults to shallower depths in the Earth's crust. The inset shows a snapshot of the methane dissociation reaction studied in this work. -  Image courtesy A. Kolesnikov and V. Kutcherov
This artistic view of the Earth’s interior shows hydrocarbons forming in the upper mantle and transported through deep faults to shallower depths in the Earth’s crust. The inset shows a snapshot of the methane dissociation reaction studied in this work. – Image courtesy A. Kolesnikov and V. Kutcherov

The oil and gas that fuels our homes and cars started out as living organisms that died, were compressed, and heated under heavy layers of sediments in the Earth’s crust. Scientists have debated for years whether some of these hydrocarbons could also have been created deeper in the Earth and formed without organic matter. Now for the first time, scientists have found that ethane and heavier hydrocarbons can be synthesized under the pressure-temperature conditions of the upper mantle -the layer of Earth under the crust and on top of the core. The research was conducted by scientists at the Carnegie Institution’s Geophysical Laboratory, with colleagues from Russia and Sweden, and is published in the July 26, advanced on-line issue of Nature Geoscience.

Methane (CH4) is the main constituent of natural gas, while ethane (C2H6) is used as a petrochemical feedstock. Both of these hydrocarbons, and others associated with fuel, are called saturated hydrocarbons because they have simple, single bonds and are saturated with hydrogen. Using a diamond anvil cell and a laser heat source, the scientists first subjected methane to pressures exceeding 20 thousand times the atmospheric pressure at sea level and temperatures ranging from 1,300 F° to over 2,240 F°. These conditions mimic those found 40 to 95 miles deep inside the Earth. The methane reacted and formed ethane, propane, butane, molecular hydrogen, and graphite. The scientists then subjected ethane to the same conditions and it produced methane. The transformations suggest heavier hydrocarbons could exist deep down. The reversibility implies that the synthesis of saturated hydrocarbons is thermodynamically controlled and does not require organic matter.

The scientists ruled out the possibility that catalysts used as part of the experimental apparatus were at work, but they acknowledge that catalysts could be involved in the deep Earth with its mix of compounds.

“We were intrigued by previous experiments and theoretical predictions,” remarked Carnegie’s Alexander Goncharov a coauthor. “Experiments reported some years ago subjected methane to high pressures and temperatures and found that heavier hydrocarbons formed from methane under very similar pressure and temperature conditions. However, the molecules could not be identified and a distribution was likely. We overcame this problem with our improved laser-heating technique where we could cook larger volumes more uniformly. And we found that methane can be produced from ethane.”

The hydrocarbon products did not change for many hours, but the tell-tale chemical signatures began to fade after a few days.

Professor Kutcherov, a coauthor, put the finding into context: “The notion that hydrocarbons generated in the mantle migrate into the Earth’s crust and contribute to oil-and-gas reservoirs was promoted in Russia and Ukraine many years ago. The synthesis and stability of the compounds studied here as well as heavier hydrocarbons over the full range of conditions within the Earth’s mantle now need to be explored. In addition, the extent to which this ‘reduced’ carbon survives migration into the crust needs to be established (e.g., without being oxidized to CO2). These and related questions demonstrate the need for a new experimental and theoretical program to study the fate of carbon in the deep Earth.”

Rainfall to decrease over Iberian Peninsula

This chart maps changes in annual and seasonal climate in the Mediterranean between 1950 and 2002. -  Juan Ignacio López-Moreno et al./ SINC
This chart maps changes in annual and seasonal climate in the Mediterranean between 1950 and 2002. – Juan Ignacio López-Moreno et al./ SINC

Scientists have recorded a decline in winter precipitation over the past 60 years in Spain, and they now forecast that precipitation will also decrease in spring and summer. A team from the Pyrenean Institute of Ecology (CSIC) has studied rainfall data from 1950 to 2006 and the climate projections for coming decades, showing that less rain will fall in future over the Iberian Peninsula. However, precipitation will continue to be more frequent in winter than in spring-summer.

Have there been any changes to the monthly contributions to total annual precipitation within the Mediterranean basin? Researchers from the Pyrenean Institute of Ecology (CSIC) have assessed the changes observed in rainfall patterns since 1950, and are predicting contributions to be lower by the middle of the 21st Century, against a backdrop of increasing greenhouse gas emissions.

“We have used the data reported (1950-2006) and simulated various climate models (2040-2060) to look at whether the monthly contribution to the annual total has changed over recent decades, and whether such changes are likely to happen over the medium term”, Juan Ignacio López-Moreno, lead author of the study, tells SINC.

The research, published recently in the journal Geophysical Research Letters, studied variability and climate change in the Mediterranean region. According to the scientists, significant changes have taken place over this area, with disparate effects being noted over the course of the year, and “uniform patterns” identified in the evolution of rain over time. In addition to the changes in the amounts of precipitation falling, López-Moreno says “the climate models suggest new changes will take place over the coming decades”.

Rainy December?

One of the most significant patterns revealed by the study is that precipitation in March in the western part of the Mediterranean basin, specifically the Iberian Peninsula, fell by 8% from 1950 to 2002, and increased by 3% in April and May over the same period. The researchers also point to a slight increase in rainfall between August and December.

Scientists are predicting a significant decline in rainfall throughout the entire Mediterranean basin, above all in spring and summer. However, observations from the past 50 years and predictions for coming decades do not show up any changes in seasonal rain distribution patterns. The research team says “while the changes observed have now been identified, they are not great enough to alter the general pattern of rainfall distribution throughout the year”.

López-Moreno says the uncertainties associated with climate models and the way in which hydrological systems will respond to climate changes make it hard to draw any immediate conclusions.

Geoengineering: The promise and its limits

Four expert speakers attended an event organised by the Institute of Physics, the Royal Society of Chemistry and the Royal Academy of Engineering on 15 July, at the House of Commons, to address an audience curious about geo-engineering the planet to combat the effects of global warming; the solutions it offers and the concerns it raises.

Introduced by Dr Brian Iddon MP, Dr Alan Gadian from the University of Leeds opened the seminar with a description of cloud albedo modification, explaining how a “cloud whitening scheme”, involving ships spraying small droplets of seawater up into the atmosphere, could help in the fight against climate change.

Dr Gadian was followed by Dr Dan Lunt from the University of Bristol, who in his presentation about sunshade engineering, described the most up-to-date range of CO2 forecasts currently being used by environmental scientists, the implications of those forecasts and how much benefit the positioning of sunshades in space, placed directly between the Earth and the Sun, held in place by gravitational forces, could have.

Following Dr Lunt, Professor Andrew Watson from the University of East Anglia discussed ocean fertilisation; dropping iron, nitrates and phosphorous in the sea to encourage the growth of plankton colonies which can sequester oceanic CO2.

Akin to the previous speakers, Professor Watson explained the boundaries and limits to this anthropogenic effort to adapt the atmosphere, “All of these ideas need further research before they can be implemented and they, at best, will only provide part of the solution.”

The three scientific talks were followed by a presentation from Professor Steve Rayner, a social scientist from the University of Oxford, who discussed the social and ethical implications of undertaking projects to alter the Earth’s natural atmosphere.

Raising the issue of moral hazard, Professor Rayner suggested that, after 50 years of telling people it is bad to put things in, or tamper with, the Earth’s atmosphere, making geo-engineering projects acceptable to the general public is going to be a hard sell.

The four talks were followed by questions from the audience on a wide range of topics: From the likely prominence of geo-engineering issues at the upcoming international climate conference, COP 15 in Copenhagen; to the level of urgency and the imminence of the climate threat we face; the money available for research projects such as those described in the talks; and, quite controversially, the issue of population control.

Tiny diamonds on Santa Rosa Island give evidence of cosmic impact

This is James Kennett (left) and Douglas J. Kennett. -  UCSB
This is James Kennett (left) and Douglas J. Kennett. – UCSB

Nanosized diamonds found just a few meters below the surface of Santa Rosa Island off the coast of Santa Barbara provide strong evidence of a cosmic impact event in North America approximately 12,900 years ago, according to a new study by scientists. Their hypothesis holds that fragments of a comet struck across North America at that time.

The research, published this week in the Proceedings of the National Academy of Sciences (PNAS), was led by James Kennett, professor emeritus at UC Santa Barbara, and Douglas J. Kennett, first author, of the University of Oregon. The two are a father-son team. They were joined by 15 other researchers.

“The pygmy mammoth, the tiny island version of the North American mammoth, died off at this time,” said James Kennett. “Since it coincides with this event, we suggest it is related.” He explained that this site, with its layer containing hexagonal diamonds, is also associated with other types of diamonds and with dramatic environmental changes and wildfires. They are part of a sedimentary layer known as the Younger Dryas Boundary.

“There was a major event 12,900 years ago,” said James Kennett. “It is hard to explain this assemblage of materials without a cosmic impact event and associated extensive wildfires. This hypothesis fits with the abrupt climatic cooling as recorded in ocean-drilled sediments beneath the Santa Barbara Channel. The cooling resulted when dust from the high-pressure, high-temperature, multiple impacts was lofted into the atmosphere, causing a dramatic drop in solar radiation.”

The tiny diamonds were buried below four meters of sediment and they correspond with the disappearance of the Clovis culture — the first well-established and distributed North American peoples. An estimated 35 types of mammals and 19 types of birds also became extinct in North America about this time.

“The type of diamond we have found — lonsdaleite — is a shock-synthesized mineral defined by its hexagonal crystalline structure,” said Douglas Kennett, associate professor of anthropology at the University of Oregon. “It forms under very high temperatures and pressures consistent with a cosmic impact. These diamonds have only been found thus far in meteorites and impact craters on earth, and appear to be the strongest indicator yet of a significant cosmic impact [during Clovis].”

The diamonds were found in association with soot, which forms in extremely hot fires, and they suggest associated regional wildfires, based on nearby environmental records. Such soot and diamonds are rare in the geological record. They were found in sediment dating to massive asteroid impacts 65 million years ago in a layer widely known as the K-T Boundary, known to be associated with the extinction of dinosaurs and many other types of organisms.

Geoscientists back from an expedition to Labrador Sea

Members of the geophysical working group deploy the streamer, the 3,000-meter-long hydrophone cable used to receive the seismic signals. -  Ronald Freibothe, Alfred Wegener Institute
Members of the geophysical working group deploy the streamer, the 3,000-meter-long hydrophone cable used to receive the seismic signals. – Ronald Freibothe, Alfred Wegener Institute

Scientists from the Alfred Wegener Institute have researched the geology of the seabed in the Labrador Sea on board of the research vessel Maria S. Merian. They have studied the so-called Eirik Drift at the southern tip of Greenland, a structure of several hundred kilometres length formed like a ridge. They discovered a submarine mountain (seamount) at the south-western fringe of their area of investigation that indicates volcanic eruptions during the past few million years.

The Eirik Drift rises 2,500 m above the surrounding seabed at the southern tip of Greenland. Sediments have been depositing there for the last ten million years, forming a ridge-like structure. These sediments are ablated by ocean currents in the Greenland Sea and deposited in the Labrador Sea. This is also known to be the case with sand displacements caused by ocean currents, for example on Sylt. Caused by changing climate – the transition from warmer times to our current climate – the current drifted and changed its strength. Additionally, icebergs transport rock material from Greenland onto the seabed. Glaciers planed it off the island, and on breaking apart into icebergs, deposited it all over the ocean. Caused by the constantly expanding and melting ice surface during the geological cycles of glacials and interglacials, this material finds its way into the Eirik Drift, too.

Therefore, the Eirik Drift is an archive for the activity of Greenland’s western boundary current and the dynamics of Greenland ice cover. Climate changes and current shifts of the last ten million years can be examined here. First results show that the drift shifted strongly to the North and the West. This event took place about 5.6 million years ago. A sediment drift can be observed for the period prior to that, but velocity and path of the current changed strongly. Researchers will be able to further analyse these data by means of computer models in order to describe these changes in more detail.

The researchers discovered something unexpected during the seismic investigation using a recording cable of 3.000 m length: “Surprisingly, an unknown elevation appeared on the images of the subsurface in the western area of the Eirik Drift, which almost breaks through the sediments to the top of the seabed at two places”, reports chief scientist Dr. Gabriele Uenzelmann-Neben from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. “The sedimentary layers are disturbed”, the geophysicist continues. This elevation at the seabed, called Mount Maria S. Merian by the researchers, is about 1.500 m high – approximately as high as the Feldberg in the Black Forest. The seamount was formed by volcanism which pushed sediments upwards. Even the youngest sediment packages are affected by this movement.

It can therefore be concluded that this is a young event have occurred during the last few million years. This result changes the picture of the geological development of the outer part of the Labrador Sea. So far it was assumed that the formation of the seafloor in the Labrador Sea (tectonic activity) ended about 45 million years ago. The discovery of the seamount indicates that the seabed at the exit of the Labrador Sea changed in more recent times. A distinct changing seabed has an enormous impact on the circulation paths of deepwater, which maintains ocean currents like the Gulf Stream.

The expedition of RV Maria S. Merian, operated by the Leitstelle Merian/Meteor of the University of Hamburg, began June 17th 2009 in Reykjavik where it also ended July 13th.

New geothermal heat extraction process to deliver clean power generation

A new method for capturing significantly more heat from low-temperature geothermal resources holds promise for generating virtually pollution-free electrical energy. Scientists at the Department of Energy’s Pacific Northwest National Laboratory will determine if their innovative approach can safely and economically extract and convert heat from vast untapped geothermal resources.

The goal is to enable power generation from low-temperature geothermal resources at an economical cost. In addition to being a clean energy source without any greenhouse gas emissions, geothermal is also a steady and dependable source of power.

“By the end of the calendar year, we plan to have a functioning bench-top prototype generating electricity,” predicts PNNL Laboratory Fellow Pete McGrail. “If successful, enhanced geothermal systems like this could become an important energy source.” A technical and economic analysis conducted by the Massachusetts Institute of Technology estimates that enhanced geothermal systems could provide 10 percent of the nation’s overall electrical generating capacity by 2050.

Click to watch PNNL’s Pete McGrail describe the process.

PNNL’s conversion system will take advantage of the rapid expansion and contraction capabilities of a new liquid developed by PNNL researchers called biphasic fluid. When exposed to heat brought to the surface from water circulating in moderately hot, underground rock, the thermal-cycling of the biphasic fluid will power a turbine to generate electricity.

To aid in efficiency, scientists have added nanostructured metal-organic heat carriers, or MOHCs, which boost the power generation capacity to near that of a conventional steam cycle. McGrail cited PNNL’s nanotechnology and molecular engineering expertise as an important factor in the development, noting that the advancement was an outgrowth of research already underway at the lab.

“Some novel research on nanomaterials used to capture carbon dioxide from burning fossil fuels actually led us to this discovery,” said McGrail. “Scientific breakthroughs can come from some very unintuitive connections.”

Ancient global warming episode holds clues to future climate

The sediment archives obtained during ocean drilling programs give scientists a glimpse into Earth's climatic history.  Inset: Deep sea sediment cores across the Paleocene-Eocene boundary. The sections of light brown color consist mainly of calcium carbonate, whereas the dark red/brown section is a clay layer, representing the onset of the interval of intense global warming and ocean acidification 55 million years ago. -  Integrated Ocean Drilling Program and J.C. Zachos
The sediment archives obtained during ocean drilling programs give scientists a glimpse into Earth’s climatic history. Inset: Deep sea sediment cores across the Paleocene-Eocene boundary. The sections of light brown color consist mainly of calcium carbonate, whereas the dark red/brown section is a clay layer, representing the onset of the interval of intense global warming and ocean acidification 55 million years ago. – Integrated Ocean Drilling Program and J.C. Zachos

When scientists take Earth’s temperature, they usually use thermometers. But when scientists want to figure out Earth’s temperature in the past, they have to rely on other tools. One of these is deep-sea sediment cores (see Figure). Deep-sea sediments contain fossil remains of tiny marine creatures and other materials that sink to the ocean floor. Over millions of years, these materials pile up and build climate archives that tell stories about Earth’s history. Today, scientists recover those archives during ocean drilling expeditions aboard research vessels such as the JOIDES Resolution (see Figure).

Now a team of scientists, led by Richard Zeebe of the University of Hawai’i at Manoa’s School of Ocean and Earth Science and Technology, has examined data from sediment cores from around the world to study an ancient global warming episode, known as the Paleocene-Eocene Thermal Maximum. This warming event occurred about 55 million years ago and provides important clues about what the future may hold. By studying the past, the researchers contribute to better forecasting the future – a principle once expressed by the English historian Edward Gibbon: “I know no way of judging of the future but by the past.”

There is little doubt among scientists that the Earth is warming because of carbon dioxide emissions from human activities. But exactly how much the Earth will warm – say until the end of the 21st century – is still uncertain. In their study published in the journal Nature Geoscience, Zeebe and his team help to resolve the question by studying a possible analog in the past. Using sediment archives and theoretical tools, they provide estimates of the amount of carbon dioxide in the atmosphere during the warming episode 55 million years ago.

The team had to go back that far in time because this event may be the only one during the past 55 million years of similar scale and pace as the current human disruption. At that time, global surface temperatures rose by 5𔃇°C within a few thousand years. At nearly the same time, a large amount of carbon was released, probably from the dissociation of oceanic methane hydrates. By comparing the change in ancient temperature and carbon dioxide levels, Zeebe and his team provide clues about the magnitude of global warming during large and rapid increases of greenhouse gases.

What the team found was quite unexpected. Based on current knowledge about Earth’s climate system, they expected a three- to eightfold increase in atmospheric carbon dioxide levels to explain the 5𔃇°C warming. Yet, they found only a less-than-twofold increase.

Zeebe, an oceanographer at UH Manoa, says: “We were pretty surprised that the increase in atmospheric carbon dioxide turned out to be so small. To explain the entire warming, you would need a whole lot more carbon.”

The consequence is that other mechanisms must have considerably contributed to the warming 55 million years ago. Unfortunately, these mechanisms are unknown at present.

“There are a few ideas what may have contributed to the additional warming. But I don’t think we fully understand these events of intense and rapid global warming,” says Zeebe.

If the additional warming in the past was a response to rising carbon dioxide, then also future warming could be much stronger than anticipated. Undoubtedly, the Earth was a different place 55 million years ago and comparison with today’s situation is imperfect. Nevertheless, the work of Zeebe and his co-workers suggests that the future climate could hold some surprises.

“By continuing to put these huge amounts of carbon dioxide in the atmosphere, we’re gambling with climate and the outcome is still uncertain,” Zeebe says.