Researchers Find Giant Helium Gas Field in Tanzania

Researchers Find Giant Helium Gas Field in Tanzania

Helium is an odorless, tasteless and colorless gas that has unique properties.

It is the first of a group of elements often referred to as the noble gases.

Helium is a critical component in many fields of scientific research and is needed in a number of high-technology processes. However, known reserves are quickly running out.

Until now helium has never been found intentionally – being accidentally discovered in small quantities during oil and gas drilling.

Now, researchers from Norway and UK have developed a brand new exploration approach. The first use of this method has resulted in the discovery of a world-class helium gas field in Tanzania.

Their research, presented in Yokohama, Japan at the Goldschmidt Geochemistry Conference, shows that volcanic activity provides the intense heat necessary to release the gas from ancient, helium-bearing rocks.

“The high concentrations of helium in the region are likely related to the heating and fracturing of the Archean Tanzanian Craton and Proterozoic Mozambique Belt by the younger arms of the East African Rift System,” the scientists said.

“The distribution of high helium seeps along active faults shows increased communication between the shallow and deep crust. This combined with the presence of gas traps in the area suggests that there may be a significant helium resource.”

“We show that volcanoes in the Rift play an important role in the formation of viable helium reserves,” said lead author Dr. Diveena Danabalan, from Durham University.

“Volcanic activity likely provides the heat necessary to release the helium accumulated in ancient crustal rocks.”

“However, if gas traps are located too close to a given volcano, they run the risk of helium being heavily diluted by volcanic gases such as carbon dioxide, just as we see in thermal springs from the region.”

“We are now working to identify the goldilocks-zone between the ancient crust and the modern volcanoes where the balance between helium release and volcanic dilution is just right.”

“We sampled helium gas (and nitrogen) just bubbling out of the ground in the Tanzanian East African Rift Valley,” added co-author Prof. Chris Ballentine, from the University of Oxford.

“By combining our understanding of helium geochemistry with seismic images of gas trapping structures, independent experts have calculated a probable resource of 54 Billion Cubic Feet (BCf) in just one part of the Rift Valley.”

To put this discovery into perspective, global consumption of helium is about 8 BCf per year and the U.S. Federal Helium Reserve, which is the world’s largest supplier, has a current reserve of just 24.2 BCf.

“Total known reserves in the USA are around 153 BCf. This is a game changer for the future security of society’s helium needs and similar finds in the future may not be far away,” Prof. Ballentine said.

Distant earthquakes can cause underwater landslides

Distant earthquakes can cause underwater landslides

Researchers analyzing data from ocean bottom seismometers off the Washington-Oregon coast tied a series of underwater landslides on the Cascadia Subduction Zone, 80 to 161 kilometers (50 to 100 miles) off the Pacific Northwest coast, to a 2012 magnitude-8.6 earthquake in the Indian Ocean — more than 13,500 kilometers (8,390 miles) away. These underwater landslides occurred intermittently for nearly four months after the April earthquake.

Previous research has shown earthquakes can trigger additional earthquakes on other faults across the globe, but the new study shows earthquakes can also initiate submarine landslides far away from the quake.

“The basic assumption … is that these marine landslides are generated by the local earthquakes,” said Paul Johnson, an oceanographer at the University of Washington in Seattle and lead author of the new study published in the Journal of Geophysical Research: Solid Earth, a journal of the American Geophysical Union. “But what our paper said is, ‘No, you can generate them from earthquakes anywhere on the globe.'”

The new findings could complicate sediment records used to estimate earthquake risk. If underwater landslides could be triggered by earthquakes far away, not just ones close by, scientists may have to consider whether a local or a distant earthquake generated the deposits before using them to date local events and estimate earthquake risk, according to the study’s authors.

The submarine landslides observed in the study are smaller and more localized than widespread landslides generated by a great earthquake directly on the Cascadia margin itself, but these underwater landslides generated by distant earthquakes may still be capable of generating local tsunamis and damaging underwater communications cables, according to the study authors.

A happy accident

The discovery that the Cascadia landslides were caused by a distant earthquake was an accident, Johnson said.

Scientists had placed ocean bottom seismometers off the Washington-Oregon coast to detect tiny earthquakes, and also to measure ocean temperature and pressure at the same locations. When Johnson found out about the seismometers at a scientific meeting, he decided to analyze the data the instruments had collected to see if he could detect evidence of thermal processes affecting seafloor temperatures, such as methane hydrate formation.

Johnson and his team combined the seafloor temperature data with pressure and seismometer data and video stills of sediment-covered instruments from 2011-2015. Small variations in temperature occurred for several months, followed by large spikes in temperature over a period of two to 10 days. They concluded these changes in temperature could only be signs of multiple underwater landslides that shed sediments into the water. These landslides caused warm, shallow water to become denser and flow downhill along the Cascadia margin following the 8.6-magnitude Indian Ocean earthquake on April 11, 2012, causing the temperature spikes.

The Cascadia margin runs for more than 1,100 kilometers (684 miles) off the Pacific Northwest coastline from north to south, encompassing the area above the underlying subduction zone, where one tectonic plate slides beneath another.

Steep underwater slopes hundreds of feet high line the margin. Sediment accumulates on top of these steep slopes. When the seismic waves from the Indian Ocean earthquake reached these steep underwater slopes, they jostled the thick sediments piled on top of the slopes. This shaking caused areas of sediment to break off and slide down the slope, creating a cascade of landslides all along the slope. The sediment did not fall all at once so the landslides occurred for up to four months after the earthquake, according to the authors.

The steeper-than-average slopes off the Washington-Oregon coast, such as those of Quinault Canyon, which descends 1,420 meters (4,660 feet) at up to 40-degree angles, make the area particularly susceptible to submarine landslides. The thick sediment deposits also amplify seismic waves from distant earthquakes. Small sediment particles move like ripples suspended in fluid, amplifying the waves.

“So these things are all primed, ready to collapse, if there is an earthquake somewhere,” Johnson said.

Disrupting the sediment record

The new finding could have implications for tsunamis in the region and may complicate estimations of earthquake risk, according to the study’s authors.

Subduction zones like the Cascadia margin are at risk for tsunamis. As one tectonic plate slides under the other, they become locked together, storing energy. When the plates finally slip, they release that energy and cause an earthquake. Not only does this sudden motion give any water above the fault a huge shove upward, it also lowers the coastal land next to it as the overlying plate flattens out, making the shoreline more vulnerable to the waves of displaced water.

Submarine landslides increase this risk. They also push ocean water out of the way when they occur, which could spark a tsunami on the local coast, Johnson said.

Scientists also use underwater sediment records to estimate earthquake risk. By drilling sediment cores offshore and calculating the age between landslide deposits, scientists can create a timeline of past earthquakes used to predict how often an earthquake might occur in the region in the future and how intense it could be.

An earthquake off the Pacific Northwest would create submarine landslides all along the coast from British Columbia to California. But the new study found that a distant earthquake might only result in landslides up to 20 or 30 kilometers (12 to 19 miles) wide. That means when scientists take sediment cores to determine how frequent local earthquakes occur, they may not be able to tell if the sediment layers arrived on the seafloor as a result of a distant or local earthquake.

Johnson says more core sampling over a wider range of the margin would be needed to determine a more accurate reading of the geologic record and to update estimates of earthquake risk.

Putnisite: New Mineral Discovered in Australia

Putnisite: New Mineral Discovered in Australia

The new mineral is named putnisite after Drs Christine and Andrew Putnis from the University of Münster, Germany, for their outstanding contributions to mineralogy.

Putnisite occurs as isolated pseudocubic crystals, up to 0.5 mm in diameter, and is associated with quartz and a near amorphous Cr silicate.

It is translucent, with a pink streak and vitreous lustre. It is brittle and shows one excellent and two good cleavages parallel to {100}, {010} and {001}.

“What defines a mineral is its chemistry and crystallography. By x-raying a single crystal of mineral you are able to determine its crystal structure and this, in conjunction with chemical analysis, tells you everything you need to know about the mineral,” explained Dr Elliott, who, along with colleagues, described putnisite in the Mineralogical Magazine.

“Most minerals belong to a family or small group of related minerals, or if they aren’t related to other minerals they often are to a synthetic compound – but putnisite is completely unique and unrelated to anything.”

Putnisite combines the elements strontium, calcium, chromium, sulfur, carbon, oxygen and hydrogen:

SrCa4Cr83+(CO3)8SO4(OH)16•25H2O

The mineral has a Mohs hardness of 1.5–2, a measured density of 2.20 g/cm3 and a calculated density of 2.23 g/cm3. It was discovered during prospecting by a mining company in Western Australia.

“Nature seems to be far cleverer at dreaming up new chemicals than any researcher in a laboratory,” Dr Elliott concluded.

New map highlights sinking Louisiana coast

New map highlights sinking Louisiana coast

The map, published in GSA Today, has long been considered the “holy grail” by researchers and policy makers as they look for solutions to the coastal wetland loss crisis, the researchers said.

“The novel aspect of this study is that it provides a map that shows subsidence rates as observed at the land surface,” said Torbjörn Törnqvist, professor of geology and chair of the Department of Earth and Environmental Sciences at Tulane University.

“This sets it apart from previous attempts to map subsidence rates.”

Jaap Nienhuis, a postdoctoral fellow in earth and environmental sciences, is the lead author of the study. He said that while the present-day subsidence rate averages about nine millimeters, or just over a third of an inch each year, there is plenty of variability among specific sites along the coast.

“This information will be valuable for policy decisions about coastal restoration, such as planning of large sediment diversions that are intended to make portions of Louisiana’s coast more sustainable,” Nienhuis said.

The researchers used data obtained by a network of hundreds of instruments known as surface-elevation tables, scattered along the Louisiana coast. These instruments enabled the Tulane team to calculate subsidence rates in the shallow subsurface (up to about 10 meters or 30 feet depth) where most of the subsidence happens. This large network of surface-elevation tables was installed during the post-Katrina period, so determining subsidence rates with this method has only recently become possible.

20 Ancient Supervolcanoes Discovered in Utah and Nevada

20 Ancient Supervolcanoes Discovered in Utah and Nevada

Supervolcanoes are giant volcanoes that blast out more than 1,000 cubic km of volcanic material when they erupt. They are different from the more familiar stratovolcanoes because they aren’t as obvious to the naked eye and affect enormous areas.

“Supervolcanoes as we’ve seen are some of Earth’s largest volcanic edifices, and yet they don’t stand as high cones. At the heart of a supervolcano instead, is a large collapse. Those collapses in supervolcanoes occur with the eruption and form enormous holes in the ground in plateaus, known as calderas,” said Dr Eric Christiansen of Brigham Young University, who is a co-author of two papers published in the journal Geosphere (paper 1 & paper 2).

The newly discovered supervolcanoes aren’t active today, but 30 million years ago more than 5,500 cubic km of magma erupted during a one-week period near a place called Wah Wah Springs.

“In southern Utah, deposits from this single eruption are 4 km thick. Imagine the devastation – it would have been catastrophic to anything living within hundreds of miles,” Dr Christiansen said.

Dinosaurs were already extinct during this time period, but what many people don’t know is that 25-30 million years ago, North America was home to rhinos, camels, tortoises and even palm trees.

Dr Christiansen with colleagues measured the thickness of the pyroclastic flow deposits. They used radiometric dating, X-ray fluorescence spectrometry, and chemical analysis of the minerals to verify that the volcanic ash was all from the same ancient super-eruption.

The scientists found that the Wah Wah Springs eruption buried a vast region extending from central Utah to central Nevada and from Fillmore on the north to Cedar City on the south. They even found traces of ash as far away as Nebraska.

The team also found evidence of 15 super-eruptions and 20 large calderas – the so-called Indian Peak-Caliente caldera complex.

These supervolcanoes have diameters up to 60 km and are filled with intracaldera tuff and breccias. They have been hidden in plain sight for millions of years despite their enormous size.

“The ravages of erosion and later deformation have largely erased them from the landscape, but our careful work has revealed their details. The sheer magnitude of this required years of work and involvement of dozens of students in putting this story together,” Dr Christiansen said.

‘Bulges’ in volcanoes could be used to predict eruptions

‘Bulges’ in volcanoes could be used to predict eruptions

Using a technique called ‘seismic noise interferometry’ combined with geophysical measurements, the researchers measured the energy moving through a volcano. They found that there is a good correlation between the speed at which the energy travelled and the amount of bulging and shrinking observed in the rock. The technique could be used to predict more accurately when a volcano will erupt. Their results are reported in the journal Science Advances.

Data was collected by the US Geological Survey across Kīlauea in Hawaii, a very active volcano with a lake of bubbling lava just beneath its summit. During a four-year period, the researchers used sensors to measure relative changes in the velocity of seismic waves moving through the volcano over time. They then compared their results with a second set of data which measured tiny changes in the angle of the volcano over the same time period.

As Kīlauea is such an active volcano, it is constantly bulging and shrinking as pressure in the magma chamber beneath the summit increases and decreases. Kīlauea’s current eruption started in 1983, and it spews and sputters lava almost constantly. Earlier this year, a large part of the volcano fell away and it opened up a huge ‘waterfall’ of lava into the ocean below. Due to this high volume of activity, Kīlauea is also one of the most-studied volcanoes on Earth.

The Cambridge researchers used seismic noise to detect what was controlling Kīlauea’s movement. Seismic noise is a persistent low-level vibration in the Earth, caused by everything from earthquakes to waves in the ocean, and can often be read on a single sensor as random noise. But by pairing sensors together, the researchers were able to observe energy passing between the two, therefore allowing them to isolate the seismic noise that was coming from the volcano.

“We were interested in how the energy travelling between the sensors changes, whether it’s getting faster or slower,” said Clare Donaldson, a PhD student in Cambridge’s Department of Earth Sciences, and the paper’s first author. “We want to know whether the seismic velocity changes reflect increasing pressure in the volcano, as volcanoes bulge out before an eruption. This is crucial for eruption forecasting.”

One to two kilometres below Kīlauea’s lava lake, there is a reservoir of magma. As the amount of magma changes in this underground reservoir, the whole summit of the volcano bulges and shrinks. At the same time, the seismic velocity changes. As the magma chamber fills up, it causes an increase in pressure, which leads to cracks closing in the surrounding rock and producing faster seismic waves — and vice versa.

“This is the first time that we’ve been able to compare seismic noise with deformation over such a long period, and the strong correlation between the two shows that this could be a new way of predicting volcanic eruptions,” said Donaldson.

Volcano seismology has traditionally measured small earthquakes at volcanoes. When magma moves underground, it often sets off tiny earthquakes, as it cracks its way through solid rock. Detecting these earthquakes is therefore very useful for eruption prediction. But sometimes magma can flow silently, through pre-existing pathways, and no earthquakes may occur. This new technique will still detect the changes caused by the magma flow.

Seismic noise occurs continuously, and is sensitive to changes that would otherwise have been missed. The researchers anticipate that this new research will allow the method to be used at the hundreds of active volcanoes around the world.

Diamonds and Chocolate: New Volcanic Process Discovered

Diamonds and Chocolate: New Volcanic Process Discovered

The team studied how a process called ‘fluidized spray granulation’ can occur during kimberlite eruptions to produce well-rounded particles containing fragments from the Earth’s mantle, most notably diamonds. This physical process is similar to the gas injection and spraying process used to form smooth coatings on confectionary, and layered and delayed-release coatings in the manufacture of pharmaceuticals and fertilizers.

Kimberlite volcanoes are the primary source of diamonds on Earth, and are formed by gas-rich magmas from mantle depths of over 150 km. Kimberlite volcanism involves high-intensity explosive eruptions, forming diverging pipes or ‘diatremes’, which can be several hundred meters wide and several kilometers deep. A conspicuous and previously mysterious feature of these pipes are ‘pelletal lapilli ’ – well-rounded magma coated fragments of rock consisting of an inner ‘seed’ particle with a complex rim, thought to represent quenched magma.

These pelletal lapilli form by spray granulation when kimberlite magma intrudes into earlier volcaniclastic infill close to the diatreme root zone. Intensive degassing produces a gas jet in which the seed particles are simultaneously fluidized and coated by a spray of low-viscosity melt.

In kimberlites, the occurrence of pelletal lapilli is linked to diamond grade (carats per tonne), size and quality, and therefore has economic as well as academic significance.

“The origin of pelletal lapilli is important for understanding how magmatic pyroclasts are transported to the surface during explosive eruptions, offering fundamental new insights into eruption dynamics and constraints on vent conditions, notably gas velocity,” said Dr. Thomas Gernon, a lecturer in earth science at the University of Southampton and a lead author of the study published in the journal Nature Communications.

“The ability to tightly constrain gas velocities is significant, as it enables estimation of the maximum diamond size transported in the flow. Gas fluidisation and magma-coating processes are also likely to affect the diamond surface properties.”

The scientists studied two of the world’s largest diamond mines in South Africa and Lesotho. In the Letseng pipe in Lesotho, pelletal lapilli have been found in association with concentrations of large diamonds (up to 215 carat), which individually can fetch up to tens of millions of pounds. Knowledge of flow dynamics will inform models of mineral transport, and ultimately could improve resource assessments.

“This multidisciplinary research, incorporating Earth sciences, chemical and mechanical engineering, provides evidence for fluidized granulation in natural systems which will be of considerable interest to engineers and chemical, pharmaceutical and food scientists who use this process routinely. The scale and complexity of this granulation process is unique, as it has not previously been recognized in natural systems,” Dr. Gernon concluded.

Early Earth’s Atmosphere was Similar to Present-Day One

Early Earth’s Atmosphere was Similar to Present-Day One

Scientists have used the oldest minerals on Earth to reconstruct the atmospheric conditions. The findings, published in the journal Nature, prove that the atmosphere of early Earth was dominated by the  oxygen-rich compounds found within our current atmosphere – including water, carbon dioxide, and sulfur dioxide.

“We can now say with some certainty that many scientists studying the origins of life on Earth simply picked the wrong atmosphere,” said Bruce Watson, Professor of Science at Rensselaer Polytechnic Institute. The findings rest on the widely held theory that Earth’s atmosphere was formed by gases released from volcanic activity on its surface. Today, as during the earliest days of the Earth, magma flowing from deep in the Earth contains dissolved gases. When that magma nears the surface, those gases are released into the surrounding air.

“Most scientists would argue that this outgassing from magma was the main input to the atmosphere,” Watson said. “To understand the nature of the atmosphere ‘in the beginning,’ we needed to determine what gas species were in the magmas supplying the atmosphere.”

As magma approaches the Earth’s surface, it either erupts or stalls in the crust, where it interacts with surrounding rocks, cools, and crystallizes into solid rock. These frozen magmas and the elements they contain can be literal milestones in the history of Earth. One important milestone is zircon. The scientists sought to determine the oxidation levels of the magmas that formed ancient zircons to quantify, for the first time ever, how oxidized were the gases being released early in Earth’s history. “By determining the oxidation state of the magmas that created zircon, we could then determine the types of gases that would eventually make their way into the atmosphere,” said Dustin Trail, lead author of the study .

To do this researchers recreated the formation of zircons in the laboratory at different oxidation levels. They literally created lava in the lab. This procedure led to the creation of an oxidation gauge that could then be compared with the natural zircons.

During this process they looked for concentrations of a rare Earth metal called cerium in the zircons. Cerium is an important oxidation gauge because it can be found in two oxidation states, with one more oxidized than the other. The higher the concentrations of the more oxidized type cerium in zircon, the more oxidized the atmosphere likely was after their formation.

The calibrations reveal an atmosphere with an oxidation state closer to present-day conditions.

Why the Sumatra earthquake was so severe

Why the Sumatra earthquake was so severe

The earthquake, measuring magnitude 9.2, and the subsequent tsunami, devastated coastal communities of the Indian Ocean, killing over 250,000 people.

Research into the earthquake was conducted during a scientific ocean drilling expedition to the region in 2016, as part of the International Ocean Discovery Program (IODP), led by scientists from the University of Southampton and Colorado School of Mines.

During the expedition on board the research vessel JOIDES Resolution, the researchers sampled, for the first time, sediments and rocks from the oceanic tectonic plate which feeds the Sumatra subduction zone. A subduction zone is an area where two of the Earth’s tectonic plates converge, one sliding beneath the other, generating the largest earthquakes on Earth, many with destructive tsunamis.

Findings of a study on sediment samples found far below the seabed are now detailed in a new paper led by Dr Andre Hüpers of the MARUM-Center for Marine Environmental Sciences at University of Bremen – published in the journal Science.

Expedition co-leader Professor Lisa McNeill, of the University of Southampton, says: “The 2004 Indian Ocean tsunami was triggered by an unusually strong earthquake with an extensive rupture area. We wanted to find out what caused such a large earthquake and tsunami and what this might mean for other regions with similar geological properties.”

The scientists concentrated their research on a process of dehydration of sedimentary minerals deep below the ground, which usually occurs within the subduction zone. It is believed this dehydration process, which is influenced by the temperature and composition of the sediments, normally controls the location and extent of slip between the plates, and therefore the severity of an earthquake.

In Sumatra, the team used the latest advances in ocean drilling to extract samples from 1.5 km below the seabed. They then took measurements of sediment composition and chemical, thermal, and physical properties and ran simulations to calculate how the sediments and rock would behave once they had travelled 250 km to the east towards the subduction zone, and been buried significantly deeper, reaching higher temperatures.

The researchers found that the sediments on the ocean floor, eroded from the Himalayan mountain range and Tibetan Plateau and transported thousands of kilometres by rivers on land and in the ocean, are thick enough to reach high temperatures and to drive the dehydration process to completion before the sediments reach the subduction zone. This creates unusually strong material, allowing earthquake slip at the subduction fault surface to shallower depths and over a larger fault area – causing the exceptionally strong earthquake seen in 2004.

Dr Andre Hüpers of the University of Bremen says: “Our findings explain the extent of the large rupture area, which was a feature of the 2004 earthquake, and suggest that other subduction zones with thick and hotter sediment and rocks, could also experience this phenomenon.

“This will be particularly important for subduction zones with limited or no historic subduction earthquakes, where the hazard potential is not well known. Subduction zone earthquakes typically have a return time of a few hundred to a thousand years. Therefore our knowledge of previous earthquakes in some subduction zones can be very limited.”

Similar subduction zones exist in the Caribbean (Lesser Antilles), off Iran and Pakistan (Makran), and off western USA and Canada (Cascadia). The team will continue research on the samples and data obtained from the Sumatra drilling expedition over the next few years, including laboratory experiments and further numerical simulations, and they will use their results to assess the potential future hazards both in Sumatra and at these comparable subduction zones.