Major Deep Carbon Sink Linked To Microbes Found Near Volcano Chains

Up to about 19 percent more carbon dioxide than previously believed is removed naturally and stored underground between coastal trenches and inland chains of volcanoes, keeping the greenhouse gas from entering the atmosphere, according to a study in the journal Nature.

Surprisingly, subsurface microbes play a role in storing vast amounts of carbon by incorporating it in their biomass and possibly by helping to form calcite, a mineral made of calcium carbonate, Rutgers and other scientists found. Greater knowledge of the long-term impact of volcanoes on carbon dioxide and how it may be buffered by chemical and biological processes is critical for evaluating natural and human impacts on the climate. Carbon dioxide is the major greenhouse gas linked to global warming.

“Our study revealed a new way that tiny microorganisms can have an outsized impact on a large-scale geological process and the Earth’s climate,” said co-author Donato Giovannelli, a visiting scientist and former post-doc in the Department of Marine and Coastal Sciences at Rutgers University-New Brunswick. He is now at the University of Naples in Italy.

Giovannelli is a principal investigator for the interdisciplinary study, which involves 27 institutions in six nations. Professor Costantino Vetriani in the Department of Marine and Coastal Sciences and Department of Biochemistry and Microbiology in the School of Environmental and Biological Sciences is one of the Rutgers co-authors. The study covers how microbes alter the flow of volatile substances that include carbon, which can change from a solid or liquid to a vapor, in subduction zones. Such zones are where two tectonic plates collide, with the denser plate sinking and moving material from the surface into Earth’s interior.

The subduction, or geological process, creates deep-sea trenches and volcanic arcs, or chains of volcanoes, at the boundary of tectonic plates. Examples are in Japan and South and Central America. Arc volcanoes are hot spots for carbon dioxide emissions that re-enter the atmosphere from subducted material, which consists of marine sediment, oceanic crust and mantle rocks, Giovannelli said. The approximately 1,800-mile-thick mantle of semi-solid hot rock lies beneath the Earth’s crust.

The Earth’s core, mantle and crust account for 90 percent of carbon. The other 10 percent is in the ocean, biosphere and atmosphere. The subduction zone connects the Earth’s surface with its interior, and knowing how carbon moves between them is important in understanding one of the key processes on Earth and regulating the climate over tens of millions of years.

The study focused on the Nicoya Peninsula area of Costa Rica. The scientists investigated the area between the trench and the volcanic arc – the so-called forearc. The research reveals that volcanic forearc are a previously unrecognized deep sink for carbon dioxide.

Data Mining Digs Up Hidden Clues To Major California Earthquake Triggers

A powerful computational study of southern California seismic records has revealed detailed information about a plethora of previously undetected small earthquakes, giving a more precise picture about stress in the earth’s crust. A new publicly available catalog of these findings will help seismologists better understand the stresses triggering the larger earthquakes that occasionally rock the region.

“It’s very difficult to unpack what triggers larger earthquakes because they are infrequent, but with this new information about a huge number of small earthquakes, we can see how stress evolves in fault systems,” said Daniel Trugman, a post-doctoral fellow at Los Alamos National Laboratory and coauthor of a paper published in the journal Science today. “This new information about triggering mechanisms and hidden foreshocks gives us a much better platform for explaining how big quakes get started,” Trugman said.

Crunching the Numbers

Trugman and coauthors from the California Institute of Technology and Scripps Institution of Oceanography performed a massive data mining operation of the Southern California Seismic Network for real quakes buried in the noise. The team was able to detect, understand, and locate quakes more precisely, and they created the most comprehensive earthquake catalog to date. The work identified 1.81 million quakes — 10 times more earthquakes occurring 10 times more frequently than quakes previously identified using traditional seismology methods.

The team developed a comprehensive, detailed earthquake library for the entire southern California region, called the Quake Template Matching (QTM) catalog. They are using it to create a more complete map of California earthquake faults and behavior. This catalog may help researchers detect and locate quakes more precisely.

The team analyzed nearly two decades of data collected by the Southern California Seismic Network. The network, considered one of the world’s best seismic systems, amasses a catalog of quakes from 550 seismic monitoring stations in the region. The SCSN catalog is based entirely on the traditional approach: manual observation and visual analysis. But Trugman says this traditional approach misses many weak signals that are indicators of small earthquakes.

Matching Templates Is Key

The team improved on this catalog with data mining. Using parallel computing, they crunched nearly 100 terabytes of data across 200 graphics processing units. Zooming in at high resolution for a 10-year period, they performed template matching using seismograms (waveforms or signals) of previously identified quakes. To create templates, they cut out pieces of waveforms from previously recorded earthquakes and matched those waveforms to patterns of signals recorded simultaneously from multiple seismic stations. Template matching has been done before, but never at this scale.

“Now we can automate it and search exhaustively through the full waveform archive to find signals of very small earthquakes previously hidden in the noise,” Trugman explained.

Applying the templates found events quake precursors, foreshocks and small quakes that had been missed with manual methods. Those events often provide key physical and geographic details to help predict big quakes. The team also identified initiation sequences that reveal how quakes are triggered.

New details also revealed three-dimensional geometry and fault structures, which will support development of more realistic models.

Recently, Trugman and Los Alamos colleagues have applied machine learning to study earthquakes created in laboratory quake machines. That works has uncovered important details about earthquake behavior that may be used to predict quakes.

“In the laboratory, we see small events as precursors to big slip events, but we don’t see this consistently in the real world. This big data template-matching analysis bridges the gap,” he said. “And now we’ve discovered quakes previously discounted as noise and learned more about their behavior. If we can identify these sequences as foreshocks in real time, we can predict the big one.”

Tracking Records Of The Oldest Life Forms On Earth

The discovery provides a new characteristic ‘biosignature’ to track the remains of ancient life preserved in rocks which are significantly altered over billions of years and could help identify life elsewhere in the Solar System.

The research, published in two papers — one in the Journal of the Geological Society and another in Earth and Planetary Science Letters — solves the longstanding problem of how scientists can track records of life on Earth in highly metamorphosed rocks more than 3,700 million years old, with organic material often turning into the carbon-based mineral graphite.

In the first study, published in Earth and Planetary Science Letters, the team analysed ten rock samples of banded iron formations (BIF) from Canada, India, China, Finland, USA and Greenland spanning over 2,000 million years of history.

They argue that carbon preserved in graphite-like crystals -‘graphitic carbon’- located alongside minerals such as apatite, which our teeth and bones are made of, and carbonate, are the biosignatures of the oldest life forms on Earth.

“Life on Earth is all carbon-based and over time, it decomposes into different substances, such as carbonate, apatite and oil. These become trapped in layers of sedimentary rock and eventually the oil becomes graphite during subsequent metamorphism in the crust,” explained Dr Dominic Papineau (UCL Earth Sciences, Center for Planetary Sciences and the London Centre for Nanotechnology).

“Our discovery is important as it is hotly debated whether the association of graphite with apatite is indicative of a biological origin of the carbon found in ancient rocks. We now have multiple strands of evidence that these mineral associations are biological in banded iron formations. This has huge implications for how we determine the origin of carbon in samples of extra-terrestrial rocks returned from elsewhere in the Solar System.”

The team investigated the composition of BIF rocks as they are almost always of Precambrian age (4,600 million years old to 541 million years old) and record information about the oldest environments on Earth.

For this, they analysed the composition of rocks ranging from 1,800 million years old to more than 3,800 million years old using a range of methods involving photons, electrons, and ions to characterise the composition of graphite and other minerals of potential biogenic origin.

“Previously, it was assumed that finding apatite and graphite together in ancient rocks was a rare occurrence but this study shows that it is commonplace in BIF across a range of rock metamorphic grades,” said team member Dr Matthew Dodd (UCL Earth Sciences and the London Centre for Nanotechnology).

The apatite and graphite minerals are thought to have two possible origins: mineralised products of decayed biological organic matter, which includes the breakdown of molecules in oil at high temperatures, or formation through non-biological reactions which are relevant to the chemistry of how life arose from non-living matter.

By showing evidence for the widespread occurrence of graphitic carbon in apatite and carbonate in BIF along with its carbon-isotope composition, the researchers conclude that the minerals are most consistent with a biological origin from the remains of Earth’s oldest life forms.

To investigate the extent to which high-temperature metamorphism causes a loss in molecular, elemental and isotope signatures from biological matter in rocks, they analysed the same minerals from a 1,850 million year old BIF rock in Michigan which had metamorphosed in 550 degree Celsius heat.

In this second study, published today in Journal of the Geological Society, the team show that several biosignatures are found in the graphitic carbon and the associated apatite, carbonate and clays.

They used a variety of high-tech instruments to detect traces of key molecules, elements, and carbon isotopes of graphite and combined this with several microscopy techniques to study tiny objects trapped in rocks which are invisible to the naked eye.

Together, all of their observations of the composition are consistent with an origin from decayed biomass, such as that of ancient animal fossils in museums, but which has been strongly altered by high temperatures.

“Our new data provide additional lines of evidence that graphite associated with apatite in BIF is most likely biological in origin. Moreover, by taking a range of observations from throughout the geological record, we resolve a long-standing controversy regarding the origin of isotopically light graphitic carbon with apatite in the oldest BIF,” said Dr Papineau.

“We’ve shown that biosignatures exist in highly metamorphosed iron formations from Greenland and northeastern Canada which are more than 3,850 million years old and date from the beginning of the sedimentary rock record.”

The work was kindly funded in part by NASA.

Large Antarctic Ice Shelf, Home To A UK Research Station, Is About To Break Apart

Glaciology experts have issued evidence that a large section of the Brunt Ice Shelf in Antarctica, which is home to the British Antarctic Survey’s Halley Research Station, is about break off.

The rifting started several years ago and is now approaching its final phase. In anticipation of the iceberg breaking away, the research station, which is currently unmanned, has been relocated to a safer location on the ice shelf, meaning there is no danger posed to personnel.

The iceberg, measuring over 1,500 square kilometres — which is twice the size of New York City — is expected to break away from the Brunt Ice Shelf in as little as a few months, when two large cracks which have been growing over the past seven years meet.

Now academics from Northumbria University, in Newcastle upon Tyne, UK, in collaboration with scientists from ENVEO, a remote sensing company in Austria, have submitted new research to the journal The Cryosphere, which shows that the break-off is part of the ice shelf’s natural lifecycle, and that similar events may have occurred in the past.

As Professor Hilmar Gudmundsson of Northumbria explains: “I have been carrying out research in this area for more than 15 years and have been monitoring the growth of the cracks since they first emerged in 2012.

“Satellite images of the changes in the ice shelf have been shared online and there has been much speculation about the cause of this movement and the impact the iceberg will have when it breaks away.

“However, what many people do not realise is that this is a natural process and something which has happened time and again. We recognise that climate change is a serious problem which is having an impact around the world, and particularly in the Antarctic. However, there is no indication from our research that this particular event is related to climate change.

“We have been tracking the movement of the ice shelf for many years and our modelling indicates that this breakaway is entirely expected. That is why in 2014 we recommended that the Halley Research Station was moved to a new and safe location on the ice shelf.

“Our field observations and modelling has meant that the station was safely relocated with no danger to the scientists using it and minimal disruption to the research taking place.”

The Brunt Ice Shelf is a large floating area of ice, around 150m to 250m thick, and is made up of freshwater ice which originally fell as snow further inland. The ice shelf rests on top of the Weddell Sea and flows off the mainland, moving outwards from the centre of Antarctica.

As ice shelves are afloat, any icebergs that form as a result of fractures in the ice do not contribute to sea level rise. “Once the iceberg breaks away from the Brunt Ice Shelf it is likely to drift towards the west and slowly break up into smaller icebergs,” explains Dr Jan De Rydt, also of Northumbria University.

This isn’t the first time a large piece of ice shelf has broken away in Antarctica. The Pine Island Ice Shelf in West Antarctica has seen several large sections break off in recent years, and the Larsen C Ice Shelf to the West of the Brunt Ice Shelf has lost a section more than 3,600 square miles due to calving — when ice chunks break from the edge of a glacier — in 2017.

And there is historic evidence to show the Brunt Ice Shelf has seen similar large calving events in the past. As Professor Gudmundsson explains: “Maps drawn by Shackleton and Wordie during their expedition to the Brunt Ice Shelf in 1915 show that, at that time, the ice shelf was quite extended. However, by the time the Halley Research Station was established in the 1950s the reach of the ice shelf was much shorter, indicating that a large iceberg must have broken away at some point after 1915. This further backs up our research that this type of event is historically consistent and part of the natural cycle and movement of the ice shelf.”

Dr De Rydt and Professor Gudmundsson’s paper, Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice-shelf geometry, is currently undergoing peer review in the European Geosciences Union journal The Cryosphere.

The paper is co-authored by Thomas Nagler and Jan Wuite of ENVEO (Environmental Earth Observation), in Innsbruck, Austria, who have worked closely with Professor Gudmundsson and Dr De Rydt during the research. ENVEO is a world-leader in processing satellite data for monitoring changes in the global snow and ice cover. The two teams have been collaborating together for several years on a number of projects, with scientists from ENVEO using satellite imagery to extract data about the changing speed of the ice shelf, which is then shared with researchers at Northumbria University for modelling and interpretation.

Dr Jan Wuite of ENVEO said: “Thanks to the Copernicus Sentinel-1 and Sentinel-2 satellites we can now continuously monitor the movement of the ice shelf and the propagation of the cracks in great detail and in near real-time. These observational data are very useful for improving existing ice flow models.”

Dr Thomas Nagler of ENVEO added: “This work is the result of the long-lasting partnership between the glaciologists from Northumbria University and remote sensing experts from ENVEO, that has already led to several previous publications on Brunt Ice Shelf.”

Earth’s Deep Mantle Flows Dynamically

As ancient ocean floors plunge over 1,000 km into the Earth’s deep interior, they cause hot rock in the lower mantle to flow much more dynamically than previously thought, finds a new UCL-led study.

The discovery answers long-standing questions on the nature and mechanisms of mantle flow in the inaccessible part of deep Earth. This is key to understanding how quickly Earth is cooling, and the dynamic evolution of our planet and others in the solar system.

“We often picture the Earth’s mantle as a liquid that flows but it isn’t — it’s a solid that moves very slowly over time. Traditionally, it’s been thought that the flow of rock in Earth’s lower mantle is sluggish until you hit the planet’s core, with most dynamic action happening in the upper mantle which only goes to a depth of 660 km. We’ve shown this isn’t the case after all in large regions deep beneath the South Pacific Rim and South America,” explained lead author, Dr Ana Ferreira (UCL Earth Sciences and Universidade de Lisboa).

“Here, the same mechanism we see causing movement and deformation in the hot, pressurised rock in the upper mantle is also occurring in the lower mantle. If this increased activity is happening uniformly over the globe, Earth could be cooling more rapidly than we previously thought,” added Dr Manuele Faccenda, Universita di Padova.

The study, published today in Nature Geoscience by researchers from UCL, Universidade de Lisboa, Universita di Padova, Kangwon National University and Tel Aviv University, provides evidence of dynamic movement in the Earth’s lower mantle where ancient ocean floors are plunging towards the planet’s core, crossing from the upper mantle (up to ~660 km below the crust) to the lower mantle (~660 — 1,200 km deep).

The team found that the deformation and increased flow in the lower mantle is likely due to the movement of defects in the crystal lattice of rocks in the deep Earth, a deformation mechanism called “dislocation creep,” whose presence in the deep mantle has been the subject of debate.

The researchers used big data sets collected from seismic waves formed during earthquakes to probe what’s happening deep in Earth’s interior. The technique is well established and comparable to how radiation is used in CAT scans to see what’s happening in the body.

“In a CAT scan, narrow beams of X-rays pass through the body to detectors opposite the source, building an image. Seismic waves pass through the Earth in much the same way and are detected by seismic stations on the opposite side of the planet to the earthquake epicentre, allowing us to build a picture of the structure of Earth’s interior,” explained Dr Sung-Joon Chang, Kangwon National University.

By combining 43 million seismic data measurements with dynamic computer simulations using the UK’s supercomputing facilities HECToR, Archer and the Italian Galileo Computing Cluster, CINECA the researchers generated images to map how the Earth’s mantle flows at depths of ~1,200 km beneath our feet.

They revealed increased mantle flow beneath the Western Pacific and South America where ancient ocean floors are plunging towards Earth’s core over millions of years.

This approach of combining seismic data with geodynamic computer modelling can now be used to build detailed maps of how the whole mantle flows globally to see if dislocation creep is uniform at extreme depths.

The researchers also want to model how material moves up from the Earth’s core to the surface, which together with this latest study, will help scientists better understand how our planet evolved into its present state.

“How mantle flows on Earth might control why there is life on our planet but not on other planets, such as Venus, which has a similar size and location in the solar system to Earth, but likely has a very different style of mantle flow. We can understand a lot about other planets from revealing the secrets of our own,” concluded Dr Ferreira.

Earth’s Magnetic Pole Shifting at Unexpected Speed

Rapid shifts in the Earth’s north magnetic pole are forcing researchers to make an unprecedented early update to a model that helps navigation by ships, planes and submarines in the Arctic, scientists said.

Compass needles point towards the north magnetic pole, a point which has crept unpredictably from the coast of northern Canada a century ago to the middle of the Arctic Ocean, moving towards Russia.

Arnaud Chulliat is a scientist at the University of Colorado in Boulder, Colorado. He is also the lead researcher for the newly updated World Magnetic Model. Chulliat told the Associated Press the continuous movement of magnetic north is a problem for compasses in smartphones and other electronic devices.

“It is moving at about 50 km (30 miles) a year. It did not move much between 1900 and 1980 but it is really accelerated in the past 40 years,” reports Ciaran Beggan, of the British Geological Survey in Edinburgh.

A five-year update of a World Magnetic Model was due in 2020 but the U.S. military requested an unprecedented early review, he said. The BGS runs the model with the U.S. National Oceanic and Atmospheric Administration.

Beggan said the moving pole affected navigation, mainly in the Arctic Ocean north of Canada. NATO and the U.S. and British militaries are among those using the magnetic model, as well as civilian navigation.

The wandering pole is driven by unpredictable changes in liquid iron deep inside the Earth. An update will be released on January 30, the journal Nature said, delayed from January 15 because of the U.S. government shutdown.

“The fact that the pole is going fast makes this region more prone to large errors,” Arnaud Chulliat, a geomagnetist at the University of Colorado Boulder and NOAA’s National Centers for Environmental Information, told Nature.

Beggan said the recent shifts in the north magnetic pole would be unnoticed by most people outside the Arctic, for instance using smartphones in New York, Beijing or London.

Many smartphones have inbuilt compasses to help to orientate maps or games such as Pokemon Go. In most places, however, the compass would be pointing only fractionally wrong, within errors allowed in the five-year models, Beggan said.

Innovative Method Enables New View Into Earth’s Interior

An innovative X-ray method enables new high-pressure investigations of samples under deep mantle conditions. The technique, which was developed by a team led by Georg Spiekermann from DESY, the German Research Centre for Geosciences GFZ and the University of Potsdam, extends the range of instruments available to high-pressure researchers. Successful tests of the new method at DESY’s X-ray light source PETRA III support the idea that heavy elements have to accumulate in magmas so that they could be stable at depths of Earth’s lower mantle. The scientists present their work in the journal Physical Review X.

The so-called standard conditions of chemistry, i.e. a temperature of 25 degrees Celsius and a pressure of 1013 millibar, are actually rare in nature. Most of the matter in the universe exists under completely different conditions. In Earth’s interior, for example, pressure and temperature rise rapidly to many times the standard conditions. “However, even with the most elaborate deep drilling, only the uppermost part of the Earth’s crust is accessible,” Spiekermann emphasises. Researchers therefore simulate the conditions of Earth’s interior in the laboratory in order to investigate the behaviour of matter under these conditions.

Such experiments often involve determining the inner structure of the samples, which in many materials changes with increasing pressure. This inner structure can be explored with X-rays that are energetic enough to penetrate the sample and short enough in wavelength to resolve the tiny details of atomic distances. For this purpose, usually two X-ray based methods exist in high-pressure research: absorption and diffraction of X-rays through the sample.

Based on X-ray emission, Spiekermann and his team have now developed a third method that can be used to determine both the bonding distances in compressed amorphous (disordered) matter and the so-called coordination number, which indicates how many direct neighbours an atom has. These parameters can be read from the energy and intensity of the radiation of a certain emission line of the sample, called Kβ” (“K-beta-doubleprime”). The Kβ” radiation is generated when the sample is excited with X-rays. The energy of the emission line depends on the coordination number, the intensity on the bonding distance.

Experiments at the experimental station P01 at DESY’s X-ray source PETRA III have confirmed the new method. “We have shown this, using the spectrum of germanium in compressed amorphous germanium dioxide, but this procedure can also be applied to other chemical systems,” says Spiekermann.

The method will provide scientists with an additional technique for investigating the structure of high-pressure samples. “The insight provided by a new measuring method is particularly welcome when different methods have so far produced significantly different results so far, as in the case of compressed amorphous germanium dioxide,” explains DESY researcher Hans-Christian Wille, head of the measuring station P01 at which the experiments took place.

For their experiments, the researchers exposed samples of germanium dioxide (GeO2) to a pressure of up to 100 gigapascals, about one million times as much as the atmospheric pressure at sea level. This pressure corresponds to a depth of 2200 kilometres in the lower mantle of Earth. The measurements show that the coordination number of germanium dioxide does not rise higher than six even under this extreme pressure. This means that even in the high-pressure phase, the germanium atoms each still have six neighbouring atoms as already at 15 gigapascals.

This result is of great interest for the exploration of Earth’s interior, because germanium dioxide has the same structure and behaves like silicon dioxide (SiO2), which is the main component of natural magmas in general. Since melts such as magma generally have a lower density than the solid form of the same material, it has long been a mystery why magmas at great depth do not rise towards the surface over geological periods.

“There are two possible explanations for this, one chemical, the other structural,” Spiekermann explains. “Either heavy elements such as iron accumulate in the melt, or there is a special compacting mechanism in melts that makes melts denser than crystalline forms of the same composition.” The latter would be noticeable, among other things, by an increase in the coordination number under high pressure.

“Our investigations show that up to 100 gigapascals the coordination number in non-crystalline germanium dioxide is not higher than in the corresponding crystalline form,” reports the researcher. Applied to silicon dioxide, this means that magma with a higher density can only be produced by enriching relatively heavy elements such as iron. The composition and structure of the lower mantle have far-reaching consequences for the global transport of heat and the propagation of Earth’s magnetic field.