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Types of Volcanoes

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A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Earth’s volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. For example, a mid-oceanic ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates coming together. Volcanoes can also form where there is stretching and thinning of the crust’s interior plates, e.g., in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America. This type of volcanism falls under the umbrella of “plate hypothesis” volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called “hotspots”, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Volcanoes are usually not created where two tectonic plates slide past one another.

Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. One such hazard is that volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature; the melted particles then adhere to the turbine blades and alter their shape, disrupting the operation of the turbine. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth’s lower atmosphere (or troposphere); however, they also absorb heat radiated up from the Earth, thereby warming the upper atmosphere (or stratosphere). Historically, so-called volcanic winters have caused catastrophic famines.

Types of Volcanoes

  1. Shield volcanoes
  2. Cinder cones
  3. Composite volcanoes

1- Shield volcanoes

A shield volcano is a type of volcano usually built almost entirely of fluid magma flows. They are named for their large size and low profile, resembling a warrior’s shield lying on the ground. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from stratovolcanoes. This results in the steady accumulation of broad sheets of lava, building up the shield volcano’s distinctive form. The shape of shield volcanoes is due to the low-viscosity magma of their mafic lava.

2- Cinder cones

Cinder cones are the simplest type of volcano. A cinder cone or scoria cone is a steep conical hill of loose pyroclastic fragments, such as either volcanic clinkers, cinders, volcanic ash, or scoria that has been built around a volcanic vent. They consist of loose pyroclastic debris formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is beautifully symmetrical; with slopes between 30-40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit.

3- Composite volcanoes

A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic explosive eruptions and effusive eruptions, although some have collapsed craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).

Stratovolcanoes are sometimes called “composite volcanoes” because of their composite layered structure built up from sequential outpourings of eruptive materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. Two famous stratovolcanoes are Krakatoa, best known for its catastrophic eruption in 1883 and Vesuvius, famous for its destruction of the towns Pompeii and Herculaneum in 79 CE. Both eruptions claimed thousands of lives. In modern times, Mount Saint Helens and Mount Pinatubo have erupted catastrophically.

Existence of stratovolcanoes has not been proved on other terrestrial bodies of the solar system with one exception. Their existence was suggested for some isolated massifs on Mars, e.g., Zephyria Tholus.

Reference:
U.S. Geological Survey: Principal Types of Volcanoes
British Geological Survey: Types of volcano
Wikipedia: Shield volcano
Wikipedia: Cinder cone
Wikipedia: Stratovolcano

Giant Blobs of Rock, Deep Inside the Earth, Hold Important Clues About Our Planet

Giant Blobs of Rock, Deep Inside-GeologyPage
Cutaway of the Earth’s surface, down to the liquid core. A numerical convection experiment shows blobs in green, surrounding mantle rock in blue, and former oceanic crust from the surface that has subducted into the interior in yellow. Credit: Dr. Mingming Li/University of Colorado

Two massive blob-like structures lie deep within Earth, roughly on opposite sides of the planet. The two structures, each the size of a continent and 100 times taller than Mount Everest, sit on the core, 1,800 miles deep, and about halfway to the center of Earth.

Arizona State University scientists Edward Garnero, Allen McNamara and Sang-Heon (Dan) Shim, of the School of Earth and Space Exploration, suggest these blobs are made of something different from the rest of Earth’s mantle. The scientists’ work appears in the June issue of Nature Geoscience.

“While the origin and composition of the blobs are yet unknown,” said Garnero, “we suspect they hold important clues as to how Earth was formed and how it works today.”

The blobs, he says, may also help explain the plumbing that leads to some massive volcanic eruptions, as well as the mechanism of plate tectonics from the convection, or stirring, of the mantle. This is the geo-force that drives earthquakes.

Deep stirring

Earth is layered like an onion, with a thin outer crust, a thick viscous mantle, a fluid outer core and a solid inner core. The two blobs sit in the mantle on top of Earth’s core, under the Pacific Ocean on one side and beneath Africa and the Atlantic Ocean on the other.

Waves from earthquakes passing through Earth’s deep interior have revealed that these blobs are regions where seismic waves travel slowly. The mantle materials that surround these regions are thought to be composed of cooler rocks, associated with the downward movement of tectonic plates.

The blobs, also called thermochemical piles, have long been depicted as warmer-than-average mantle materials, pushed upward by a slow churning of hot mantle rock. The new paper argues they are also chemically different from the surrounding mantle rock, and may partly contain material pushed down by plate tectonics. They might even be material left over from Earth’s formation, 4.5 billion years ago.

Much is yet to be learned about these blobs. But the emerging view from seismic and geodynamic information is that they appear denser than the surrounding mantle materials, are dynamically stable and long-lived, and have been shaped by the mantle’s large-scale flow. The scientists expect that further work on the two deep-seated anomalies will help clarify the picture and tell of their origin.

“If a neuroscientist found an unknown structure in the human brain, the whole community of brain scientists, from psychologists to surgeons, would actively pursue understanding its role in the function of the whole system,” Garnero said.

“As the thermochemical piles come into sharper focus, we hope other Earth scientists will explore how these features fit into the big puzzle of planet Earth.”

Reference:
Edward J. Garnero, Allen K. McNamara, Sang-Heon Shim. Continent-sized anomalous zones with low seismic velocity at the base of Earth’s mantle. Nature Geoscience, 2016; DOI: 10.1038/NGEO2733

Note: The above post is reprinted from materials provided by Arizona State University (ASU).

Geologists Make Their Own Lava to Prep for Explosive Experiments

Geologists Make Their Own Lava-GeologyPage
Red-hot. Inside the furnace, rock has begun to melt to form lava. Credit: Ingo Sonder

How do you make your own lava?

Dump 10 gallons of basaltic rock into a high-powered induction furnace. Let it heat up for 3 or 4 hours. Stir occasionally with a steel rod. Once the mixture is red hot and bubbling at 2,500 degrees Fahrenheit, pour it out.

That’s the recipe, according to University at Buffalo geologists who are melting 10 gallons of rock at a time to prep for explosive experiments anticipated later this summer.

The work is taking place at a geohazards field station in Ashford, New York, about 40 miles south of Buffalo. The facility, run by UB’s Center for GeoHazards Studies, is equipped with microphones, thermal cameras, pressure sensors and other gear that the scientists will use to record what happens when they expose their molten rock to water.

Lava-water interactions are common in nature but poorly understood.

They drive the formation of volcanic maar craters, such as Hunt’s Hole in New Mexico or Lake Nyos in Cameroon. They can also enhance the explosive potential of ice-covered volcanoes, such as Iceland’s Eyjafjallajökull, whose 2010 eruption unleashed an ash cloud that grounded air traffic across much of Europe for nearly a week.

The UB lava-making operation — one of the largest in the world — will provide a rare, close-up view of the interplay between molten rock and water. The research will yield insight on why the two substances sometimes generate huge explosions when they come together, and sometimes cause no damage at all.

“The eruption at Eyjafjallajökull was more explosive due to the presence of water,” says project lead Ingo Sonder, a research scientist at UB’s Center for GeoHazards Studies. “Events like that don’t happen often, but there is a threat of a big impact when they do. As geologists, we want to understand the conditions that generate explosions — how much water do you need? How much time?”

The answers could help scientists better gauge the danger that volcanoes near ice, lakes, oceans and underground water sources pose to surrounding communities.

Scaling up lava science

Experiments on water and lava have been done on a smaller scale, with a lot less lava, at Universität Würzburg in Germany, where Sonder previously worked. His UB team will build on the Würzburg research by using larger quantities of both materials to better mimic natural volcanic settings.

“Previous studies have used a coffee cup-sized amount of lava,” says UB geology postdoctoral researcher Alison Graettinger. “They did it at a small-scale. We’re doing it bigger, because there are a lot of questions about whether we’ll see the same results when experiments are scaled up.”

The research, funded by the National Science Foundation, will be overseen by a core group that includes Sonder, Graettinger and UB geology professor Greg Valentine, who directs the Center for GeoHazards Studies in UB’s College of Arts and Sciences.

After the scientists perfect their rock-melting process, the explosive lava-water experiments will start.

The tests will involve pouring the lava — called “the melt” — into a slim, 4-foot-long metal box that simulates the narrow channels through which molten rock flows inside volcanoes. Then, the team will inject the lava with water to see what happens. Each experiment will use a nearly 10-gallon batch of melt, and the scientists expect to go through hundreds of gallons of lava by the time they are done with their project.

Safety will be a priority: Those working closely with the molten rock will follow strict safety procedures, with the scientist who pours the lava donning space suit-like protective gear that includes a reflective suit, gloves and green face shielding to protect against infrared radiation.

“It’s exciting to be doing this science,” Graettinger says. “No one has done it before on this scale, and these lava-water interactions aren’t well understood. Sometimes when water and lava meet, the lava will appear to completely ignore the water. Sometimes, the lava will cool and form distinctive cracking patterns, or form interesting shapes like pillow lavas. And sometimes, the reaction is violent. Why?”

An international user facility for testing hazards

The Geohazards Field Station where the research is occurring began operations in 2012 at a 700-acre experimental site in Western New York.

UB’s Center for GeoHazards Studies is working to develop portions of the site as an international user facility — a place where scientists worldwide can come and run large-scale experiments simulating geological hazards. The first project done on-site, led by Valentine and Graettinger, involved detonating dynamite under gravel, ping pong and tennis balls to model how debris flies during a volcanic eruption.

The field station’s buildout is guided by feedback from the scientific community, including about 50 geohazards experts who met at UB in 2010 to discuss field research needs. The lava furnace provides unique experimental capabilities at the site and, eventually, could be available for use by other researchers, Valentine says.

Video

Note: The above post is reprinted from materials provided by University at Buffalo.

Remains of mammoth uncovered in Mexico

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Mexican experts are carefully digging up fossils of a Pleistocene-era mammoth believed to have been cut to pieces by ancient humans.

Remains of the giant wooly mammal, believed to be some 14,000 years old, were discovered by chance in December near Mexico City while drainage pipes were being installed in the village of Tultepec.

Archaeologists have been working at the site since April, and they hope to complete their work in the next few days.

Luis Cordoba, an archaeologist with the National Institute of Anthropology and History, said the remains of more than fifty mammoths have been discovered in the area around the capital, where in pre-historic times there was a shallow saltwater lake where the heavy creatures often got stuck.

The lake was also very good for preserving the remains.

Other mammoth remains have been found in the Tultepec area, “but this is the first time that they can be studied because in general people do not report the finds in time,” Cordoba said.

When alive, the mammoth was 3.5 meters high, five meters long, weighed around five tonnes, and was between the ages of 20 and 25.

The Tultepec mammoth, which is about three-quarters complete and well preserved, still has tusks attached to its skull.

However the remaining fossils “do not maintain an anatomical order,” Cordoba said, suggesting the mammoth was cut up by humans for its meat or pelt.

Scientists hope to eventually assemble the fossils and put them on display.

Note: The above post is reprinted from materials provided by AFP.

Congo volcano brings farmers rich soil but eruption threat

Congo volcano brings farmers-GeologyPage
In this March 29, 2010 file photo, a resident walks past banana trees near the base of Mount Nyiragongo, one of Africa’s most active volcanos, in Goma, Congo. Traumatized farmers are slowly returning to fields decimated by the 2002 eruption of Mount Nyiragongo in eastern Congo. Flowing lava flattened more than 30 percent of the city of Goma, 20 kilometers away. Credit: AP Photo/Rebecca Blackwell,File

Hacking away in the midday sun, 49-year-old farmer Daniel Lazuba remembers vividly his life before one of Africa’s most active volcanos erupted 14 years ago.

“All of this was corn before,” he said as he pointed to rows of new banana trees pushing up between black stones. “My cabbage seems to be growing better than ever these days, but in this area, I still have to start from zero.”

Traumatized farmers like Lazuba are slowly returning to fields decimated by the 2002 eruption of Mount Nyiragongo in eastern Congo. Flowing lava flattened more than 30 percent of the city of Goma, 20 kilometers away. Nearly 150 people died, and 400,000 fled into neighboring Rwanda.

Now farmers returning to their fields find increased harvests from the rich volcanic soil, but there are signs that Nyiragongo will erupt again.

One farmer, Patrick Tamoini, said his harvests have risen over the past two harvests since he returned to his patch of land a short walk from the volcano’s base. The 41-year-old pockets more than $100 a month after taking care of family expenses, more than double his earnings before the eruption, he said. The average per capita monthly income in Congo is nearly $32 a month, according to the World Bank.

But returning to the fields wasn’t easy.

“The pain of what I lost kept me from coming back for such a long time,” Tamoini said. “With this level of production, I’m glad I finally did.”

The chemical makeup of volcanic soil makes for lucrative farming conditions, say researchers at the Goma Volcano Observatory.

“Lava actually enriches the soil that it initially burned,” said Mathieu Yalira, the chair of observatory’s geochemistry and environment department. Volcanic soil includes fertilizing elements such as iron, phosphorus and potassium, he said. In the years after an eruption, a process known as chemical weathering slowly makes lava soil more fertile than ordinary earth.

Local farmers didn’t seize on those benefits right away, observers say.

“Initially, no one was coming back because they were too devastated to see their burned fields,” said the chair of the observatory’s seismology department, Georges Mavonga. “But within the past year, visits toward the volcano have shown new villages in areas that were uninhabited before.”

He said the increase in lava soil farming may be a result of initial farmers seeing the benefits and spreading information to friends and family.

But the farmers should not get too attached to the newly fertile fields, warns the Rwanda Red Cross, which cared for many fleeing the 2002 eruption.

In February, an earthquake far beneath the surface caused rumbling noises near Virunga National Park, where the volcano is located. Since then, a new vent has appeared on the northeastern edge of the crater floor that shoots lava into the air every 30 seconds.

The Rwanda Red Cross has increased surveillance of the volcano in conjunction with the observatory.

“There are only presumptions about the next eruption, but people who study the daily life of this volcano tell us it could happen any day,” said Yves Riupi, a Red Cross crisis manager who works with seismologists at the Rwanda Natural Resources Authority.

The risk of another eruption is one that some farmers, whose lives depend on their crops, are now willing to take.

With vegetation growing more than six feet tall in some places with the rich volcanic soil, farmers say they want to keep working their fields, until the volcano erupts.

“If another one comes, who am I to stop it?” Lazuba asked. “There is nothing I can do.”

Note: The above post is reprinted from materials provided by The Associated Press.

New technique settles old debate on highest peaks in US Arctic

New technique settles old-GeologyPage
Mt Isto, the tallest peak in the US Arctic, shown as a 3-D visualization of fodar data. Yellow dots indicate position of some of the ground control GPS data collected during the climbing expedition. Closely spaced points are on the climb up, widely spaced points are on the ski down. Credit: Nolan & DesLauriers, The Cryosphere, 2016/Fairbanks Fodar

Finding out which is the highest mountain in the US Arctic may be the last thing on your mind, unless you are an explorer who skis from the tallest peaks around the globe. Ski mountaineer Kit DesLauriers joined forces with glaciologist Matt Nolan to settle a debate of more than 50 years, while testing a new, affordable mapping technique in a steep mountainous region. Their research is published in The Cryosphere, an open access journal of the European Geosciences Union (EGU).

At 6190m, Denali is the uncontested highest peak in North America, but beyond the Arctic Circle, a debate remains as to which US mountain can be crowned the tallest. Depending on the scale of the map you look at, the 1950s US Geological Survey’s topographic maps of the eastern Alaska Arctic show either Mt Chamberlin or Mt Isto as the highest mountain in the region.

“These mountain peaks just happened to be located in the same area as the glaciers we were studying and several of the peaks ended up in our maps,” says Nolan, a professor at the University of Alaska Fairbanks and the lead-author of the study. He had been mapping glacier volume change in the Brooks Range using a technique called fodar, which he invented. “Because we were interested in understanding the performance limitations of fodar in steep mountain terrain, it seemed a natural fit to combine this validation testing with settling the debate on which peak was the tallest.”

Fodar is used to survey and map terrain using airborne photography. It’s similar to airborne lidar, which relies on laser equipment mounted on an aircraft to scan the landscape and create 3D maps of the terrain, but is much more affordable. “The core equipment is a modern, professional DSLR camera, a high-quality lens, a survey-grade GPS unit, and some custom electronics to link the camera to the GPS,” Nolan explains.

“A modern airborne lidar unit that can map steep mountain terrain like the one we studied costs over 500,000 USD and typically requires a twin engine plane and a separate equipment operator. In contrast, the fodar hardware costs under 30,000 USD if bought new (much cheaper if you buy used) and can be operated by the pilot flying in a small single-engine plane.”

Taking to the skies, Nolan flew his Cessna 170B to map the Brooks Range peaks. Meanwhile, DesLauriers, a professional athlete and the first person to ski down the highest peaks of the 7 continents, was on the ground climbing up and then skiing down Mt Isto and Mt Chamberlin. During the trek, she tracked her position using the same type of GPS unit Nolan used in his plane.

“The GPS antenna, mounted to a steel post in my backpack, required a constant unobstructed view of the sky which forced me to find creative ways to adapt my usual ski carrying system while climbing,” DesLauriers says. “Instead of a normal rest stop to eat and hydrate, I used the rare moments standing still to note my location and time in a field journal so that Matt could have as much data as possible to compare our measurements. The process made climbing the peaks, which took on average a 10 hr summit push after a multi-day approach, more difficult but also more rewarding.”

Nolan explains why this challenging expedition was needed: “The general idea is to measure elevations from the air at about the same time someone is measuring them on the ground. These ground control points then get compared to the airborne measurements and the difference between them is a measure of accuracy.”

With an accuracy of better than 20cm, Nolan and DesLauriers found that Mt Isto is, at 2735.6m, the tallest peak in the US Arctic while Mt Chamberlin (2712.3m) is only the third highest peak. Fodar measurements also showed a third peak, Mt Hubley, surpasses Mt Chamberlin by about 5m, taking up second place in the list of highest US Arctic mountains. Nolan and DesLauriers believe it is plausible that the ranking has changed over time, and may continue to change as summit glaciers dwindle, though not enough to remove Mt Isto from the top.

Fodar has helped settled this debate, but the applications of the technique extend far beyond measuring mountain heights. “Though determining peak heights was a fun and useful study, our primary use for fodar is in change detection in the cryosphere [the planet’s frozen regions].” In addition to measuring peak heights, they are using the same maps to study how snow and glacier melt will affect the region.

Nolan has also used fodar to measure coastal erosion, permafrost melt, landslides, ice jams, and infrastructure degradation, mostly in Alaska. Elsewhere, he has been discussing fodar projects to study landscape and ecological change in the Galapagos, flooding dynamics in desert regions of Botswana, and even earthquake relief in Nepal. “The possibilities are truly unlimited.”

Reference:
Matt Nolan, Kit DesLauriers. Which are the highest peaks in the US Arctic? Fodar settles the debate. The Cryosphere, 2016; 10 (3): 1245 DOI: 10.5194/tc-10-1245-2016

Note: The above post is reprinted from materials provided by European Geosciences Union.

Volcanoes get quiet before they erupt

Volcanoes get quiet-GeologyPage
Photo of Tilca volcano in Nicaragua erupting. Credit: Diana Roman

When dormant volcanoes are about to erupt, they show some predictive characteristics–seismic activity beneath the volcano starts to increase, gas escapes through the vent, or the surrounding ground starts to deform. However, until now, there has not been a way to forecast eruptions of more restless volcanoes because of the constant seismic activity and gas and steam emissions.

Carnegie volcanologist Diana Roman, working with a team of scientists from Penn State, Oxford University, the University of Iceland, and INETER has shown that periods of seismic quiet occur immediately before eruptions and can thus be used to forecast an impending eruption for restless volcanoes. The duration of the silence can indicate the level of energy that will be released when eruption occurs. Longer quiet periods mean a bigger bang.

The research is published in Earth and Planetary Science Letters.

The team monitored a sequence of eruptions at the Telica Volcano in Nicaragua in 2011. It is a so-called stratovolcano, with a classic-looking cone built up by many layers of lava and ash. They started monitoring Telica in 2009 with various instruments and by 2011 they had a comprehensive network within 2.5 miles (4 kilometers) of the volcano’s summit.

The 2011 eruptive event was a month-long series of small to moderate ash explosions. Prior to the eruption, there was a lack of deep seismicity or deformation, and small changes in sulfur dioxide gas emissions, indicating that the eruption was not driven by fresh magma. Instead, the eruption likely resulted from the vents being sealed off so that gas could not escape. This resulted in an increase in the pressure that eventually caused the explosions.

Of the 50 explosions that occurred, 35 had preceding quiet periods lasting 30 minutes or longer. Thirteen explosions were preceded by quiet intervals of at least five minutes. Only two of the 50 did not have any quiet period preceding the explosion.

“It is the proverbial calm before the storm,” remarked Roman. “The icing on the cake is that we could also use these quiet periods to forecast the amount of energy released.”

The researchers did a “hindsight” analysis of the energy released. They found that the longer the quiet phase preceding an explosion, the more energy was released in the ensuing explosion. The quiet periods ranged from 6 minutes before an explosion to over 10 hours (619 minutes) for the largest explosion.

The researchers were also able to forecast a minimum energy for impending explosions based on the data from the previous quiet/explosion pairs and the duration of the particular quiet period being analyzed. The correlation between duration of quiet periods and amount of energy released is tied to the duration of the gas pathways being blocked. The longer the blockage, the more pressure builds up resulting in more energy released. Sealing might be occurring due to mineral precipitation in cracks that previously acted as gas pathways, or due to the settling of the rock near the volcano’s surface.

“What is clear is that this method of careful monitoring of Telica or other similar volcanoes in real time could be used for short-term forecasts of eruptions,” Roman said. “Similar observations of this phenomenon have been noted anecdotally elsewhere. Our work has now quantified that quiet periods can be used for eruption forecasts and that longer quiet periods at recently active volcanoes could indicate a higher risk of energetic eruptions.”

The paper’s other authors are Mel Rodgers of Oxford University, Peter LaFemina of Penn State University, Halldor Geirsson of the University of Iceland, and Virginia Tenorio of the Instituto Nicaraguense de Estudios Territoriales.

This work was supported by the National Science Foundation and the Nicaraguan Institute of Earth Sciences (INETER).

Reference:
Diana C. Roman, Mel Rodgers, Halldor Geirsson, Peter C. LaFemina, Virginia Tenorio. Assessing the likelihood and magnitude of volcanic explosions based on seismic quiescence. Earth and Planetary Science Letters, 2016; DOI: 10.1016/j.epsl.2016.06.020

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

How the mouse outlived ‘the giant’

How the mouse outlived-GeologyPage
The maxillary canal for the trigeminal nerve (in green, right) and the corresponding pits on the snout (left) in a Therapsida Thrinaxodon. Credit: Wits University

T. rex may have been the most ferocious creature in the jungle, but something as simple as growing hair may have helped mammal-like reptiles to outlive this scary beast.

By scanning the fossil remains of mammal-like reptiles from the Karoo of South Africa, Dr Julien Benoit and his colleagues from the University of the Witwatersrand, Professors Paul Manger and Bruce Rubidge, found that these reptiles, called therapsids, may have evolved hair, and the use of whiskers as a sensory tool in order to operate at night well before the Mesozoic age and dinosaurs became the dominant terrestrial animals.

“Whiskers are an amazing sensory tool to have when you are nocturnal and the evolution of whiskers possibly assisted in the survival of the therapsids — and more specifically the probainognathians — which eventually evolved into mammals as we know them today,” says Benoit.

The rocks of the Karoo, deposited over a very long period from 300-180 million years ago, are internationally renowned for their wealth of fossils, particularly of therapsid reptiles which are the distant ancestors of mammals. Therapsids roamed the Earth and dominated terrestrial ecosystems well before dinosaurs and are known from all continents in the world, but South Africa has by far the most diverse and long-ranging record of this important group of animals. Thousands of therapsid fossils are curated in South African palaeontological research institutions.

However, despite their rich fossil record, to date no therapsid fossils have been found with evidence of hair and the fossil record of hair remains limited to mammals. Instead of looking for fossilised hair in therapsids Benoit and his colleagues used scanning technology to search for the neural structures which innervated hairs in therapsids.

By using new techniques based on computerised X-ray micro-tomography (CT scan) and digital three-dimensional modelling, Benoit found that the maxillary canal of therapsids, a bony tube in the snout of the animal that houses the trigeminal nerve, is shorter in therapsids than in reptiles.

The trigeminal nerve is the nerve that gives sensitivity to the snout of the animal, and as the maxillary canal is shortened, it allows for movement of the nerve as it branches into the soft tissue of the lip and nose where it innervates the whiskers.

“This leaves the trigeminal nerve free to follow the movements of a flexible snout. In reptiles this canal is long and the nerve is enclosed in the maxilla all along its length, which prevents any movement of the nose and lips,” says Benoit.

The multidisciplinary team’s research suggests that a mammal-like mobile snout evolved around 240-246 million years ago with the appearance of a group of therapsids called Prozostrodontia, which are direct ancestors of mammals.

The prozonstrodontians form part of the larger group of therapsids, probainognathians, a group of cynodont (dog-like) therapsids that evolved a large cerebellum and lost the parietal foramen for the third eye (an organ on the skull roof that detects light for monitoring thermoregulation and daily rhythms such as sleep).

Research in mutant mice has shown that these two mammalian features are controlled by the same gene, MSX2, which also controls the development of the mammary glands and the maintenance of body hairs. “This is the gene that makes us mammals” Benoit says.

Based on the CT based anatomical observations in probainognathians, it appears that the MSX2 gene underwent a significant change in its expression 240-246 million years ago and triggered the evolution of many typical mammalian traits including hair and whiskers, an enlarged cerebellum, complete ossification of the skull roof, and more importantly, the mammary glands, that define mammals today.

“Our research has shown that these features of mammals were already present in advanced therapsids, prior to the appearance of mammals,” says Benoit. “It also has implications for understanding how mammals survived the domination of dinosaurs during the Mesozoic period and the subsequent evolutionary success of mammals.”

Video

Reference:
J. Benoit, P. R. Manger, B. S. Rubidge. Palaeoneurological clues to the evolution of defining mammalian soft tissue traits. Scientific Reports, 2016; 6: 25604 DOI: 10.1038/srep25604

Note: The above post is reprinted from materials provided by University of the Witwatersrand.

Pterosaur flies safely home after 95 million years

Pterosaur flies safely home-GeologyPage
Michael Caldwell (L) and Philip Currie (R) pictured with the pterosaur before its return to Lebanon Credit: U of Alberta

With the help of University of Alberta scientists, a newly described pterosaur has finally flown home. This spectacular fossil material was discovered in a private Lebanese limestone quarry more than a decade ago and has led to what UAlberta paleontologist Michael Caldwell calls “priceless scientific findings.”

“This is the first complete pterosaur from Lebanon and the very first pterosaur from this age of marine-deposited rocks,” says Caldwell of the new genus and species, whose name is yet to be revealed. The animal lived in the Cenomanian era — 95 million years ago during the lowest part of the Upper Cretaceous — in the middle of what is now called the Tethys Seaway, a vast expanse of shallow seaway filled with reefs and lagoons, separating Europe from Africa and stretching all the way to southeast Asia. “That chunk of ocean was huge — think 10 or 20 times the size of the Great Barrier Reef and chock-full of living things. I’m sure our little pterosaur was living on one of the reef islands.”

The extremely fragile yet nearly perfectly preserved fossil was split into two pieces when it was discovered in its slab of limestone rock. Though the limestone quarries leftover from the ancient oceans are famously filled with fossil fish, this is the first ever complete pterosaur discovered in that region. Besides a fracture to the skull from the pick axe of a quarry worker, the skull is intact, as are the wings, legs, and body. “It is in immaculate condition as a result of a lot of delicate preparation work,” says Caldwell. “We can really see how this animal was built. It’s a nice little piece of science and a great story about rescuing this specimen from certain doom.”

The University of Alberta has long dominated the field of vertebrate paleontology, and the quarry owner allowed a team of experts to prepare and describe the specimen with the intent that it would one day be sold — an activity that is legal in Lebanon. Caldwell teamed up with his University of Alberta colleague, dinosaur paleobiologist Philip Currie along with lead authors Alexander Kellner from the National Museum in Brazil and Fabio Dalla Vecchia in Italy. The group has described the new species and genus, and scientific results are forthcoming in a prestigious journal.

From one university to another

Following a decade of stewardship at the University of Alberta, the quarry owner recently sold the pterosaur. The buyer subsequently donated the specimen to the Mineralogy Museum at Saint Joseph’s University in Beirut — the oldest university in Lebanon — to become the centrepiece of their Lebanese vertebrate fossil exhibition.

For his part, Caldwell is pleased to see that the specimen will not only continue to be used for teaching and research but also that it will be publicly exhibited back in its home country of Lebanon. A cast of the specimen now resides at the University of Alberta.

Note: The above post is reprinted from materials provided by University of Alberta.

Siberian larch forests are still linked to the ice age

Siberian larch forests are-GeologyPage
Open Northern Forest, Siberia. Credit: Alfred Wegener Institute

The Siberian permafrost regions include those areas of Earth, which heat up very quickly in the course of climate change. Nevertheless, biologists are currently observing only a minimal response in forest composition. In the places where, when considering the air temperature, pine and spruce forests should be growing, Siberian larch trees are still thriving. The cause of this paradox has been tracked using million-year-old bee pollen by scientists at the Alfred Wegener Institute, the University of Cologne, and international partner institutions.

The results suggest that the intensity of the ice ages determined how quick the vegetation adapted to warmer climate periods. In our case, that means: Because the last ice age was very cold, the vegetation of the Taiga lags behind the climate by many thousands of years. A surprisingly long period, as the researchers in the open access journal Nature Communications report.

The Potsdam scientist Ulrike Herzschuh knows the Siberian larch woods almost as well as the park on Telegrafenberg where her institute is located. Almost every summer the permafrost expert from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) spends time in the endless forests of Siberia, collecting plant samples, determining growth boundaries and collecting sediment cores from lakes.

“Based on the temperature increase in the last century the larch forests should have displaced in the tundra in the Northern Siberia and should have been invaded by pines and spruces from the south. But studies so far have shown only very small changes in the vegetation — and we were wondering why,” the AWI researcher says.

Searching for the cause, Ulrike Herzschuh and her international team travelled back 2.1 to 3.5 million years — to the Pliocene and Pleistocene periods. The scientists examined pollen that were preserved in sediments of Lake El’gygytgyn (region of Chukotka, in the Russian Far East). The scientists compared these traces of vegetation with reconstructed climate values of the warm and cold periods of that time.

The statistical analysis of the pollen data revealed a distinct pattern. Ulrike Herzschuh: “Our data shows that the vegetation in the past took up to several thousand years to adapt to climate change when there was a change from a cold period to a warm period. This is really new. Up until now, us climate researchers considered that there was a lag of decades or few hundreds of years, but not thousands.”

A look into the past indicates: The colder the ice age was, the longer the vegetation needed to adapt afterwards to the new climate of the warmer period. “In analogy to these results, this means: Due to the fact that the most recent ice age, about 20,000 years ago, was extremely cold, the permafrost spread over a large area, and forced deep rooted trees such as pines and spruces far to the south. The shallow-rooted Siberian larch trees — which only require a summer thawing of the permafrost soils of 20 to 30 centimetres — were able to survive in protected areas in the region,” explained Ulrike Herzschuh.

The larch forest however, with its dense carpet of roots protects the ice underneath from thawing. “We have observed many times in regions where the larch forest was cut down, that the permafrost melted faster than in other forested areas,” according to the AWI researcher.

The insulating effect of the larch forest could therefore be one of the reasons why it always took several thousands of years in the past, after a particularly cold ice age that the permafrost vanished and pine and spruce trees displaced the larch.

The scientific community now faces a major challenge due to the new findings about the time-delayed adaptation of vegetation: “In the wake of sustained warming of the Arctic, pines and spruces are now slowly coming to the Siberian Taiga. This means that the forests will become denser and thus also darker so they will save more heat than before. This fact in turn implies that the temperature in Siberia will rise in the distant future. Even if humankind manages to stabilise the carbon dioxide levels in the atmosphere in the near future,” says Ulrike Herzschuh. The implementation of these long-term vegetation processes is therefore urgently needed in climate models.

Reference:
Ulrike Herzschuh, H. John B. Birks, Thomas Laepple, Andrei Andreev, Martin Melles, Julie Brigham-Grette. Glacial legacies on interglacial vegetation at the Pliocene-Pleistocene transition in NE Asia. Nature Communications, 2016; 7: 11967 DOI: 10.1038/NCOMMS11967

Note: The above post is reprinted from materials provided by Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.

What did Earth’s ancient magnetic field look like?

What did Earth's ancient-GeologyPage
This is an illustration of ancient Earth’s magnetic field compared to the modern magnetic field courtesy of Peter Driscoll. Credit: Peter Driscoll

New work from Carnegie’s Peter Driscoll suggests Earth’s ancient magnetic field was significantly different than the present day field, originating from several poles rather than the familiar two. It is published in Geophysical Research Letters.

Earth generates a strong magnetic field extending from the core out into space that shields the atmosphere and deflects harmful high-energy particles from the Sun and the cosmos. Without it, our planet would be bombarded by cosmic radiation, and life on Earth’s surface might not exist. The motion of liquid iron in Earth’s outer core drives a phenomenon called the geodynamo, which creates Earth’s magnetic field. This motion is driven by the loss of heat from the core and the solidification of the inner core.

But the planet’s inner core was not always solid. What effect did the initial solidification of the inner core have on the magnetic field? Figuring out when it happened and how the field responded has created a particularly vexing and elusive problem for those trying to understand our planet’s geologic evolution, a problem that Driscoll set out to resolve.

Here’s the issue: Scientists are able to reconstruct the planet’s magnetic record through analysis of ancient rocks that still bear a signature of the magnetic polarity of the era in which they were formed. This record suggests that the field has been active and dipolar–having two poles–through much of our planet’s history. The geological record also doesn’t show much evidence for major changes in the intensity of the ancient magnetic field over the past 4 billion years. A critical exception is in the Neoproterozoic Era, 0.5 to 1 billion years ago, where gaps in the intensity record and anomalous directions exist. Could this exception be explained by a major event like the solidification of the planet’s inner core?

In order to address this question, Driscoll modeled the planet’s thermal history going back 4.5 billion years. His models indicate that the inner core should have begun to solidify around 650 million years ago. Using further 3-D dynamo simulations, which model the generation of magnetic field by turbulent fluid motions, Driscoll looked more carefully at the expected changes in the magnetic field over this period.

“What I found was a surprising amount of variability,” Driscoll said. “These new models do not support the assumption of a stable dipole field at all times, contrary to what we’d previously believed.”

His results showed that around 1 billion years ago, Earth could have transitioned from a modern-looking field, having a “strong” magnetic field with two opposite poles in the north and south of the planet, to having a “weak” magnetic field that fluctuated wildly in terms of intensity and direction and originated from several poles. Then, shortly after the predicted timing of the core solidification event, Driscoll’s dynamo simulations predict that Earth’s magnetic field transitioned back to a “strong,” two-pole one.

“These findings could offer an explanation for the bizarre fluctuations in magnetic field direction seen in the geologic record around 600 to 700 million years ago,” Driscoll added. “And there are widespread implications for such dramatic field changes.”

Overall, the findings have major implications for Earth’s thermal and magnetic history, particularly when it comes to how magnetic measurements are used to reconstruct continental motions and ancient climates. Driscoll’s modeling and simulations will have to be compared with future data gleaned from high quality magnetized rocks to assess the viability of the new hypothesis.

Reference:
Peter E. Driscoll. Simulating Two Billion Years of Geodynamo History. Geophysical Research Letters, 2016; DOI: 10.1002/2016GL068858

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

94 million-year-old climate change event holds clues for future

94 million-year-old climate-GeologyPage

A major climate event millions of years ago that caused substantial change to the ocean’s ecological systems may hold clues as to how the Earth will respond to future climate change, a Florida State University researcher said.

In a new study published in Earth and Planetary Science Letters, Assistant Professor of Geology Jeremy Owens explains that parts of the ocean became inhospitable for some organisms as the Earth’s climate warmed 94 million years ago. As the Earth warmed, several natural elements — what we think of as vitamins — depleted, causing some organisms to die off or greatly decrease in numbers.

The elements that faded away were vanadium and molybdenum, important trace metals that serve as nutrients for ocean life. Molybdenum in particular is used by bacteria to help promote nitrogen fixation, which is essential for all forms of life. “These trace metals were drawn down to levels below where primary producing organisms, the base of the ocean food chain, can survive,” Owens said. “This change inhibited biology.”

The warming of the Earth during this time period took place over millions of years. At the time, the world was a drastically different place. Palms were found in Canada and lily pads dotted the Arctic Circle, while dinosaurs existed on land.

But as the world continued to warm, it caused “a natural feedback that had a dramatic effect on the world’s ocean chemistry, which is recorded in the rock record,” Owens said.

Owens and a team of researchers examined samples of sediment provided through the Ocean Drilling Program, a National Science Foundation-supported program that uses the scientific drill ship JOIDES Resolution to recover samples beneath the ocean floor off the coast of Venezuela. They examined a 10-meter portion that they pinned to the climate turnover event by analyzing microfossils or tiny shell organisms in the layer.

Owens found that ecological communities experienced a substantial shift 94 million years ago because many types of bacteria and algae were affected by the changes in ocean nutrients.

“Some of these species didn’t totally die, but they didn’t flourish the way they used to,” Owens said.

The decrease of these trace metals also suggests a global expansion of oxygen deficiency, which could lead to larger dead zones in bodies of water around the world, meaning little to no life could exist in those areas.

That is of concern to scientists as they try to understand what will happen to the world around us as the Earth continues to warm. For scientists, the events of 94 million years ago provide a possible glimpse into future climate change scenarios.

“This is the best window to understanding future climate change,” Owens said. “It gives us insight into the cascade of events that can affect the entire ocean.” The research was funded by the National Science Foundation, NASA and the Agouron Institute.

Owens’ co-authors are Christopher Reinhard at Georgia Institute of Technology, Megan Rohrssen at Central Michigan University, and Gordon Love and Timothy Lyons of the University of California, Riverside.

Reference:
Jeremy D. Owens et al. Empirical links between trace metal cycling and marine microbial ecology during a large perturbation to Earth’s carbon cycle. Earth and Planetary Science Letters, 2016 DOI: 10.1016/j.epsl.2016.05.046

Note: The above post is reprinted from materials provided by Florida State University.

The world’s oldest farmers were insects

The world's oldest farmers -GeologyPage
Credit: H. Hilbert-Worf, James Cook University

The team, led by James Cook University’s Associate Professor Eric Roberts, discovered the oldest known example of fungus gardens within fossil termite nests from the Great Rift Valley of Africa in 25 million year old sediments.

Fungus farming termite colonies cultivate fungi in gardens in subterranean nests or chambers, helping to convert plant material into a more easily digestible food source for the termites.

Assoc Prof Roberts said that scientists had previously used DNA from modern termites to estimate the origin of termite ‘fungus farming’ behavior back to at least 25 to 30 million years ago.

This has now been confirmed using the new trace fossil evidence from Tanzania, allowing researchers to more accurately characterise the timing and evolution of this behaviour, something thought to have significantly modified the environment and landscape.

Patrick O’Connor, professor of anatomy at Ohio University, added “This type of study emphasizes the need for integrating perspectives from the fossil record with modern approaches in comparative biology–it is a holistic approach to evolutionary biology and significantly informs our understanding of environmental change in deep time.”

Study co-author Associate Professor Duur Aanen from Wageningen University said that the transition to agriculture dramatically increased the range of possible habitats for both the fungus-growing termites and their domesticated fungi, very much like humans and their domesticated crops and livestock, tens of millions of years later.

While the cradle of termite agriculture presumably was in an African rainforest, the transition to fungiculture helped the termites to disperse to less favorable dry savannas and also out-of-Africa migrations into Asia.

Assoc Prof Roberts added, “The phenomenon might have been triggered by the initial development of the Great Rift Valley in this part of eastern Africa, and the dramatic transformation of the landscape around this time.”

“This discovery pushes back the beginning of the termite-fungus symbiotic relationship to at least 31 million years ago,” said Paul Filmer, program director in the National Science Foundation (NSF)’s Directorate for Geosciences, which funded the research.

“Since some 90 percent of the wood in the dry environment studied is digested by termites, understanding the development of this symbiotic relationship is important to our knowledge of the history of carbon cycling in these forests,” he said.

The research is part of an ongoing study focused on the evolution of a poorly known portion of the Great Rift Valley known as the Rukwa Rift, which has produced an array of unexpected geologic and palaeontologic discoveries in the past few years.

Reference:
Eric M. Roberts, Christopher N. Todd, Duur K. Aanen, Tânia Nobre, Hannah L. Hilbert-Wolf, Patrick M. O’Connor, Leif Tapanila, Cassy Mtelela, Nancy J. Stevens. Oligocene Termite Nests with In Situ Fungus Gardens from the Rukwa Rift Basin, Tanzania, Support a Paleogene African Origin for Insect Agriculture. PLOS ONE, 22 Jun 2016 DOI: 10.1371/journal.pone.0156847

Note: The above post is reprinted from materials provided by James Cook University.

Ultra-thin slices of diamonds reveal geological processes

Ultra-thin slices of diamonds-GeologyPage
Diamonds in a new study reveal geological processes. Credit: R. Wirth, GFZ

Diamonds are not only beautiful and valuable gems, they also contain information of the geological history. By using ultra-thin slices of diamonds, Dorrit E. Jacob and her colleagues from the Macquarie University in Australia and the University of Sydney found the first direct evidence for the formation of diamonds by a process known as redox freezing. In this process, carbonate melts crystallize to form diamond. The slices were prepared by Anja Schreiber of the GFZ German Research Centre for Geosciences in Potsdam, Germany. The work is published in Nature Communications. The study shows that the reduction of carbonate to diamond is balanced by the oxidation of iron sulphide to iron oxides.

The researchers used the new nano-scale technique of Transmission Kikuchi Diffraction to discover rims of the iron oxide mineral magnetite just a few ten thousandths of a millimetre thick around sulphide minerals inside the diamonds. The GFZ’s Anja Schreiber prepared these slices using a focussed beam of charged atoms (ions) to ablate the surface. The already ultra-thin slices were re-thinned after being mounted on a carbon-coated copper grid. This process was carried out for the first time successfully on a grid and yielded the data set used for the study.

The results also solve a puzzle that has occupied diamond researchers for decades, namely the over-abundance of sulphide occurring as inclusions in diamond. Iron sulphides are the most common inclusions in diamond even though there is only about 0.02% of sulphur in the mantle: it now appears that the oxidation of the iron sulphides directly causes the formation of the diamonds that include them.

Reference:
D.E. Jacob, S. Piazolo, A. Schreiber & P. Trimby. Redox-freezing and nucleation of diamond via magnetite formation in the Earth’s mantle. Nature Communications, June 2016 DOI: 10.1038/NCOMMS11891

Note: The above post is reprinted from materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.

Why do intracontinental basins subside longer?

Why do intracontinental-GeologyPage
Why do intracontinental basins subside longer? 3D model of an intracontinental basin Credit: GFZ

Intracontinental basins like the North German Basin, the West Siberian Basin, the Barents Sea or the Congo Basin are large depressions of the Earth’s surface. How these basins initially start to form and why they subside over hundreds of millions of years at very slow rates – far longer than continental margins or foreland basins next to mountain chains – has so far not been explained with a general concept. Scientists from the GFZ section Basin Modelling have reevaluated the nature of the subsidence history of intracontinental basins and propose a new overall mechanism to explain the subsidence of these basins.

Intracontinental basins form in the interior of continents, far away from active plate boundaries. Initial significant extensional spreading events caused by plate tectonic activities can thereby be ruled out as an explanation. Why the basins form and subside continuously on a long term base remained enigmatic for a long time. These basins all share an enormous preservation potential and are therefore regarded by geoscientists as important archives to explore both the geodynamic history of the Earth and the geo-resources the basins contain. Dr. Mauro Cacace and Prof. Magdalena Scheck-Wenderoth, Head of the GFZ section Basin Modelling, now showed, based on 3-D thermomechanical numerical simulations, how the basins evolve in response to small to moderate extension caused by a thermal anomaly.

In a study published in the Journal of Geophysical Research Solid Earth they show that re-equilibration processes take place within the basins over geological time spans, between surface processes caused by sedimentation and thermal tension, caused by slow cooling of the deep lithosphere plate. The interplay of these equilibration processes causes variations in the strength of the plate that can explain for the subsidence. Dr. Cacace: “Intracontinental basins are dynamic systems that do not attain a state of isostatic equilibrium. The continuous subsidence can be explained by the striving for a thermal and mechanical equilibrium that is never reached”. The formation of intercontinental basins can only be explained by considering all these processes and their interdependence under proper temporal and spatial scales.

Reference:
Cacace, M., and M. Scheck-Wenderoth (2016), Why intracontinental basins subside longer: 3-D feedback effects of lithospheric cooling and sedimentation on the flexural strength of the lithosphere, Journal of Geophysical Research – Solid Earth, 121, DOI: 10.1002/2015JB012682.

Note: The above post is reprinted from materials provided by GFZ German Research Centre for Geosciences.

Is there life on Mars?

Is there life on Mars-GeologyPage
Methanosarcina soligelidi SMA-21, isolated from a Siberian permafrost soil is a survival specialist. Due to its specific metabolism and high resistance to hostile conditions this organism is considered as a model for possible life on Mars. Credit: Dirk Wagner, GFZ

A year and a half on the outer wall of the International Space Station ISS in altitude of 400 kilometers is a real challenge. Whether a primordial bacterium survives this procedure, is a scientifically interesting question. Today, the space experiment BIOMEX (Biology and Mars experiment) was brought from the International Space Station (ISS) back to Earth by the cosmonauts Tim Peake, Yury Malenchenko and Tim Kopra within their Soyuz-Capsule. In the framework of the BIOMEX project, which is coordinated by Dr. Jean-Pierre de Vera from the German Aerospace Center (DLR), microorganisms isolated from Siberian permafrost were among others exposed to Mars-like conditions in space for 18 months.

Is there life on Mars?“ This question raised by the pop artist David Bowie and addressing life on our neighboring planet remains unanswered until today. It is no doubt that the molecular building blocks of life are available in the universe and that early Mars, as a planet with moderate climate conditions, offered the potential that life developed also on our neighboring planet. To learn more about the possible life on Mars, Prof. Dirk Wagner and his team from the German Research Centre for Geosciences GFZ (Section Geomicrobiology), have done numerous experiments with the microorganism Methanosarcina soligelidi SMA-21 – a methane producing archaeon isolated from Siberian permafrost. The survivability of this microorganism was tested under extreme environmental conditions such as extremely low temperatures, high salinity, dehydration and radiation. This primordial bacterium has been found to be extremely resistant to the conditions tested. Due to the specific metabolism of Methanosarcina soligelidi and its high resistance to hostile conditions, this organism is considered as a model for possible life on Mars.

In order to test the survivability under Mars-like conditions, microorganisms along with other “candidates” were kept in the experimental module EXPOSE-R2 being exposed to the outside of the ISS for 18 months. GFZ scientist Dirk Wagner: “During this experiment, the microorganisms were kept on Mars-like minerals and exposed to a Martian atmosphere and the radiation conditions that prevail on Mars. The aim of the experiment is to test the long-term survival of Methanosarcina soligelidi under these conditions.”

Today the test-organisms returned from the ISS to their home planet, and will be thoroughly analyzed in the coming weeks at the GFZ German Research Centre for Geosciences in Potsdam, Germany. Even if the organisms should not have survived the exposure to a Mars-like environment, the remaining cell components will be examined in detail. These data will then be integrated into a biosignature database that is created in the framework of the BIOMEX project. The obtained information can be used in future missions to search for traces of life on Mars or elsewhere in the universe.

Note: The above post is reprinted from materials provided by GFZ German Research Centre for Geosciences.

A clean way to extract rare earth metals

A clean way to extract-GeologyPage
These rare-earth oxides are used as tracers to determine which parts of a watershed are eroding. Clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium. Credit: Peggy Greb, US department of agriculture

Rare earth metals — those 17 chemically similar elements at the bottom of the periodic table — are in almost every piece of technology we use from cell phones to wind turbines to electric cars. Because these elements are so similar to each other, the process of separating them is time consuming, expensive, and dangerous. Processing one ton of rare earths can produce 2,000 tons of toxic waste.

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) may have found a clean alternative.

As part of their research at SEAS, from 2009 to 2015, David Clarke, the Extended Tarr Family Professor of Materials, and his then graduate student, William Bonificio, have developed a method to separate rare earths using bacteria filters and solutions with pH no lower than hydrochloric acid.

The method was recently described in the journal Environmental Science and Technology Letters.

Harvard’s Office of Technology Development has filed patents and is actively pursuing commercial opportunities.

“Rare earths are very desirable but only if you can separate them,” said Clarke. “It’s a big ‘if’ because how can you separate ions that are almost the same size and the same charge?”

Current separation methods involve hundreds of steps and lots of hazardous chemicals.

Clarke and Bonifico found inspiration in the living world of bacteria. Bacteria filters have long been used to bioabsorb toxic elements from wastewater or filter metals from mine drainage systems. Recent research showed that some rare earths can bioabsorb, but Clarke and Bonifico wondered if all rare earths could be filtered through bacteria.

They immobilized a bacteria from marine algae on an assay filter and passed a solution of mixed rare earths (known as lanthanides) through it. The bacteria bioabsorbed all the elements as they passed — plucking them out of the solution and fixing them to their surface.

Then the team pumped solutions of various pH balances through the filter. With each successive pH wash, different rare earths detached. The researchers found that lighter lanthanides, such as Europium and Praseodymium, desorbed with higher-pH washes while heavier lanthanides, such as Thulium, Lutetium, and Ytterbium, desorbed with lower pH.

The team also found that if they wanted to separate only the heaviest metals, such as Thulium, which is commonly used in lasers and portable X-rays, they could block the bacteria’s receptors that absorb the lighter rare earths and only use a low-pH solution.

“We found that it is possible to concentrate a solution of equal concentrations of each lanthanide to nearly 50 percent of the three heaviest lanthanides in just two passes,” said Bonificio. “This surpasses existing industrial practice.”

“This is a radically different way of doing separation,” said Clarke. “We have an opportunity to harness the diversity of bacterial surface chemistry to separate and recover these valuable metals in a way that is environmentally benign.”

This research was supported by the Harvard University Center for the Environment and the Office of Naval Research.

Video

Reference:
William D. Bonificio and David R. Clarke, Rare-Earth Separation Using Bacteria. DOI: 10.1021/acs.estlett.6b00064

Note: The above post is reprinted from materials provided by Harvard John A. Paulson School of Engineering and Applied Sciences.

Cosmopolitan snow algae accelerate melting of Arctic glaciers

Cosmopolitan snow algae-GeologyPage
Red pigmented snow algae darken the surface of snow and ice in the Arctic. Credit: Liane G. Benning/GFZ

The role of red pigmented snow algae in melting Arctic glaciers has been strongly underestimated, suggests a study to be published in Nature Communications on June 22. White areas covered with snow and ice reflect sunlight; the effect is called albedo. It has been known for quite some time that red pigmented snow algae blooming on icy surfaces darken the surface which in turn leads to less albedo and a higher uptake of heat. The new study by Stefanie Lutz, postdoc at the German Research Centre for Geosciences GFZ and at the University of Leeds, shows a 13 per cent reduction of the albedo over the course of one melting season caused by red-pigmented snow algal blooms.

“Our results point out that the “bio-albedo” effect is important and has to be considered in future climate models”, says lead author Stefanie Lutz.

The red snow phenomenon occurs mainly in warm months. During late spring and summer, thin layers of meltwater form on ice and snow in the Arctic and on mountains. Liquid water and sunlight are crucial for the growth of snow algae; over the winter season they fall into a dormant state.

In their study, the team led by Stefanie Lutz and Liane G. Benning investigated the biodiversity of snow algae and other microbial communities using high-throughput genetic sequencing. They took about forty samples from 21 glaciers in the Pan-European Arctic. The sampling sites ranged from Greenland over Iceland and Svalbard to the north of Sweden.

Together with UK colleagues they found a high biodiversity within the bacteria, depending on the locations they lived, whereas the biodiversity of the snow algal communities was rather uniform. In other words: Throughout the Arctic regions, it is most probably the same algal species that cause red snow and thus accelerate melting. The blooming leads to a runaway effect: The more glaciers and snow fields thaw the more algae bloom which in turn results in a darkening of the surface which again accelerates melting. Liane G. Benning, head of the GFZ’s section “Interface Geochemistry”, says: “Our work paves the way for a universal model of algal-albedo interaction and a quantification of additional melting caused by algal blooms.”

For years, “bio-albedo has been a niche topic”, says Daniel Remias, biologist at the Fachhochschule Wels, Austria. The snow algae specialist comments on the study: “For the first time ever, researchers have investigated the large-scale effect of microorganisms on the melting of snow and ice the Arctic.” Remias visited the GFZ for an international snow algae meeting organized by Liane G. Benning.

He stresses the interdisciplinary approach of the project: “Steffi Lutz’ and Liane G. Benning’s study for the first time combines microbiological and genetic analyses of red snow algae with geochemical and mineralogical properties as well as with the albedo of their habitat.” An international, UK led team, including the GFZ’s researchers will work this summer on the Greenland Ice Sheet where currently a record-breaking melting rate due to high temperatures is observed. Steffi Lutz, Liane G. Benning and UK colleagues will investigate whether and to what extent pigmented algae contribute to the record melting.

Note: The above post is reprinted from materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.

Types of Opal

Types of Opal

Opal is a hydrated amorphous form of silica; its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Because of its amorphous character, it is classed as a mineraloid, unlike the other crystalline forms of silica, which are classed as minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt.

Opal is the national gemstone of Australia. Australian opal has often been cited as accounting for 95-97% of the world’s supply of precious opal, with the state of South Australia accounting for 80% of the world’s supply. Recent data suggests that the world supply of precious opal may have changed. In 2012, Ethiopian opal production was estimated to be 14,000 kg (31,000 lb) by the United States Geological Survey. USGS data from the same period (2012), reveals that Australian opal production to be $41 million. Because of the units of measurement, it is not possible to directly compare Australian and Ethiopian opal production, but these data and others suggest that the traditional percentages given for Australian opal production may be overstated. Yet, the validity of data in the USGS report appears to conflict with that of Laurs and others and Mesfin, who estimated the 2012 Ethiopian opal output (from Wegal Tena) to be only 750 kg (1,650 lb).

The internal structure of precious opal makes it diffract light; depending on the conditions in which it formed, it can take on many colors. Precious opal ranges from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black. Of these hues, the reds against black are the most rare, whereas white and greens are the most common. It varies in optical density from opaque to semitransparent.

Common opal, called “potch” by miners, does not show the display of color exhibited in precious opal.

Types of Opal

Black Opal

Locality: Grawin & Glengarry Opal Fields,Lightning Ridge, Finch Co.,New South Wales, Australia Dimensions: 23 mm x 10 mm x 3.8 mm Copyright © Miklos Brezanszky

Black opal is characterised by a dark body tone causing brightness of colour which is unmatched by lighter opals. Black Opals are usually mined in Lightning Ridge, New South Wales, and are the most famous, and sought-after type of opal. The term ‘black opal’ does not mean that the stone is completely black (a common mistake), it simply means the stone has a dark body tone in comparison to a white opal.

Australian black opals are the most valuable and widely known type of opal. Black opal is characterised by a dark body tone which can range from dark grey to jet black. (See the following chart). However this refers only to the general body tone of the stone, and is not related to the rainbow or spectral colours present in the opal. Some people expect a black opal to be completely black (in which case it would be completely worthless).

White Opal

11.0 x 7.0 x 2.5 mm

Also known as ‘milky opal’, white opal features light white body tones, and is mined in South Australia. White opal is more common and because of its body tone, generally does not show the colour as well as black opal. Nevertheless, white opals can still be absolutely magnificent in colour if a good quality stone is found.

Boulder Opal

Locality: Queensland, Australia Dimensions: 123 mm x 65 mm x 45 mm Copyright © Lopatkin Oleg

Boulder opal forms on ironstone boulders in Queensland. This type of opal is often cut with the ironstone left on the back, as the opal seam is usually quite thin. Leaving the ironstone on the back means that boulder opal can be very dark and beautiful in colour. The opal forms within the cavities of the boulders in both vertical and horizontal cracks. Boulders vary in shape and size, from as small as a pea, to as big as a family car. Boulder Opal has a tendency to cleave; when cleaved the “split” leaves two faces of opal, with a naturally polished face.

Crystal Opal

7.75 ct. Lightning Ridge Crystal Opal Credit: Mardon Jewelers

Crystal opal is any of the above kind of opal which has a transparent or semi-transparent body tone – i.e. you can see through the stone. Crystal opal can have a dark or light body tone, leading to the terms “black crystal opal” and “white crystal opal”.

Fire Opal

Locality: Opal Butte, Morrow Co., Oregon, USA 3 cm wide specimen Copyright © Peter Cristofono

Is a transparent to translucent opal, with warm body colors of yellow to orange to red. Although it does not usually show any play of color, occasionally a stone will exhibit bright green flashes. The most famous source of fire opals is the state of Querétaro in Mexico; these opals are commonly called Mexican fire opals. Fire opals that do not show play of color are sometimes referred to as jelly opals. Mexican opals are sometimes cut in their ryholitic host material if it is hard enough to allow cutting and polishing. This type of Mexican opal is referred to as a Cantera opal. Also, a type of opal from Mexico, referred to as Mexican water opal, is a colorless opal which exhibits either a bluish or golden internal sheen.

Girasol Opal

Is a term sometimes mistakenly and improperly used to refer to fire opals, as well as a type of transparent to semitransparent type milky quartz from Madagascar which displays an asterism, or star effect, when cut properly. However, the true girasol opal is a type of hyalite opal that exhibits a bluish glow or sheen that follows the light source around. It is not a play of color as seen in precious opal, but rather an effect from microscopic inclusions. It is also sometimes referred to as water opal, too, when it is from Mexico. The two most notable locations of this type of opal are Oregon and Mexico.

Peruvian Opal  (also called Blue Opal)

Is a semiopaque to opaque blue-green stone found in Peru, which is often cut to include the matrix in the more opaque stones. It does not display pleochroism. Blue opal also comes from Oregon in the Owhyee region, as well as from Nevada around Virgin Valley.

More Info about Opal : What Is Opal?

New analysis reveals large-scale motion around San Andreas Fault System

Aerial photo of the San Andreas Fault in the Carrizo Plain, northwest of Los Angeles. Credit: Wikipedia.
Aerial photo of the San Andreas Fault in the Carrizo Plain, northwest of Los Angeles.
Credit: Wikipedia.

An array of GPS instruments near the San Andreas Fault System in Southern California detects constant motion of Earth’s crust—sometimes large, sudden motion during an earthquake and often subtle, creeping motion. By carefully analyzing the data recorded by the EarthScope Plate Boundary Observatory’s GPS array researchers from the University of Hawai’i at Mānoa (UHM), University of Washington and Scripps Institution of Oceanography (SIO) discovered nearly 125 mile-wide “lobes” of uplift and subsidence—a few millimeters of motion each year—straddling the fault system. This large scale motion was previously predicted in models but until now had not been documented.

The GPS array records vertical and horizontal motion of Earth’s surface. Vertical motion is affected by many factors including tectonic motion of the crust, pumping of groundwater, local surface geology, and precipitation. The challenge faced by Samuel Howell, doctoral candidate at the UHM School of Ocean and Earth Science and Technology (SOEST) and lead author of the study, and co-authors was to discern the broad, regional tectonic motion from the shorter-scale, local motion.

To tease out such motions, the team used a comprehensive statistical technique to extract from the GPS data a pattern of large-scale, smoothly varying vertical motions of the local crust.

“While the San Andreas GPS data has been publicly available for more than a decade, the vertical component of the measurements had largely been ignored in tectonic investigations because of difficulties in interpreting the noisy data. Using this technique, we were able to break down the noisy signals to isolate a simple vertical motion pattern that curiously straddled the San Andreas fault,” said Howell.

The pattern resulting from their data analysis was similar in magnitude and direction to motions predicted by previously published earthquake cycle model results led by co-authors Bridget Smith-Konter, associate professor at UHM SOEST, and David Sandwell, professor at SIO.

“We were surprised and thrilled when this statistical method produced a coherent velocity field similar to the one predicted by our physical earthquake cycle models,” said Smith-Konter. “The powerful combination of a priori model predictions and a unique analysis of vertical GPS data led us to confirm that the buildup of century-long earthquake cycle forces within the crust are a dominant source of the observed vertical motion signal.”

The new findings, published today in Nature Geoscience, indicate that researchers can use GPS vertical motion measurements to better understand the structure and behavior of faults, even in times of earthquake quiescence, when no major ruptures have occurred for several decades to centuries. As scientists patiently monitor the San Andreas Fault System for indications of the next big earthquake, these results will help constrain seismic hazard estimates and may allow for a more prudent mapping of the large-scale motion resulting from the next significant rupture of the San Andreas.

Uplift (red) and subsidence (blue) around the San Andreas Fault System based on GPS data (top) confirms motion predicted by previous models (bottom). Credit: Howell et al., 2016.


Reference:
The vertical fingerprint of earthquake cycle loading in Southern California, Nature Geoscience, DOI: 10.1038/ngeo2741

Note: The above post is reprinted from materials provided by University of Hawaii at Manoa.

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