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Scientists to Track the Reaction of Crystals to the Electric Field

Scientists to Track the Reaction of Crystals to the Electric Field

The international scientific team developed a new method for measuring the response of crystals on the electric field. Credit: Peter the ...

Dinosaur Eggs Came in Many Colors—just Like Birds’

dinosaur, evolution 6:54 PM

Dinosaur Eggs Came in Many Colors—just Like Birds’

A neosauropod egg, Western Argentina. Photo: Lucas Fiorelli A new study says the colors found in modern birds' eggs did not evolv...

Geoscientists Discover an Overlooked Source for Earth's Water

Geology, NASA, water 7:41 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-U0JGqMYRPq4/W-Rm2_fISuI/AAAAAAAAQjE/Bq9nkRJb5Xovtxb0TU-KEGb3UbKnIpg3wCLcBGAs/s1600/Scientists%2Btheorize%2Bnew%2Borigin%2Bstory%2Bfor%2BEarth%2527s%2Bwater%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Geoscientists Discover an Overlooked Source for Earth's Water" border="0" data-original-height="520" data-original-width="1170" height="284" src="https://1.bp.blogspot.com/-U0JGqMYRPq4/W-Rm2_fISuI/AAAAAAAAQjE/Bq9nkRJb5Xovtxb0TU-KEGb3UbKnIpg3wCLcBGAs/s640/Scientists%2Btheorize%2Bnew%2Borigin%2Bstory%2Bfor%2BEarth%2527s%2Bwater%2B%25281%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This view of Earth's horizon was taken by an Expedition 7 crew member onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean.</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">Earth's water may have originated from both asteroidal material and gas left over from the formation of the Sun, according to new research. The new finding could give scientists important insights about the development of other planets and their potential to support life.</span><br />
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In a new study in the Journal of Geophysical Research: Planets, a journal of the American Geophysical Union, researchers propose a new theory to address the long-standing mystery of where Earth's water came from and how it got here.<br />
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The new study challenges widely-accepted ideas about hydrogen in Earth's water by suggesting the element partially came from clouds of dust and gas remaining after the Sun's formation, called the solar nebula.<br />
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To identify sources of water on Earth, scientists have searched for sources of hydrogen rather than oxygen, because the latter component of water is much more abundant in the solar system.<br />
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Many scientists have historically supported a theory that all of Earth's water came from asteroids because of similarities between ocean water and water found on asteroids. The ratio of deuterium, a heavier hydrogen isotope, to normal hydrogen serves as a unique chemical signature of water sources. In the case of Earth's oceans, the deuterium-to-hydrogen ratio is close to what is found in asteroids.<br />
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But the ocean may not be telling the entire story of Earth's hydrogen, according to the study's authors.<br />
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"It's a bit of a blind spot in the community," said Steven Desch, a professor of astrophysics in the School of Earth and Space Exploration at Arizona State University in Tempe, Arizona and co-author of the new study, led by Peter Buseck, Regents' Professor in the School of Earth and Space Exploration and School of Molecular Sciences at Arizona State University. "When people measure the [deuterium-to-hydrogen] ratio in ocean water and they see that it is pretty close to what we see in asteroids, it was always easy to believe it all came from asteroids."<br />
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More recent research suggests hydrogen in Earth's oceans does not represent hydrogen throughout the entire planet, the study's authors said. Samples of hydrogen from deep inside the Earth, close to the boundary between the core and mantle, have notably less deuterium, indicating this hydrogen may not have come from asteroids. Noble gases helium and neon, with isotopic signatures inherited from the solar nebula, have also been found in the Earth's mantle.<br />
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In the new study, researchers developed a new theoretical model of Earth's formation to explain these differences between hydrogen in Earth's oceans and at the core-mantle boundary as well as the presence of noble gases deep inside the planet.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Modeling Earth's beginning</span></h4>
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According to their new model, several billion years ago, large waterlogged asteroids began developing into planets while the solar nebula still swirled around the Sun. These asteroids, known as planetary embryos, collided and grew rapidly. Eventually, a collision introduced enough energy to melt the surface of the largest embryo into an ocean of magma. This largest embryo would eventually become Earth.<br />
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Gases from the solar nebula, including hydrogen and noble gases, were drawn in by the large, magma-covered embryo to form an early atmosphere. Nebular hydrogen, which contains less deuterium and is lighter than asteroidal hydrogen, dissolved into the molten iron of the magma ocean.<br />
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Through a process called isotopic fractionation, hydrogen was pulled towards the young Earth's center. Hydrogen, which is attracted to iron, was delivered to the core by the metal, while much of the heavier isotope, deuterium, remained in the magma which eventually cooled and became the mantle, according to the study's authors. Impacts from smaller embryos and other objects then continued to add water and overall mass until Earth reached its final size.<br />
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This new model would leave Earth with noble gases deep inside its mantle and a lower deuterium-to-hydrogen ratio in its core than in its mantle and oceans.<br />
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The authors used the model to estimate how much hydrogen came from each source. They concluded most was asteroidal in origin, but some of Earth's water did come from the solar nebula.<br />
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"For every 100 molecules of Earth's water, there are one or two coming from solar nebula," said Jun Wu, assistant research professor in the School of Molecular Sciences and School of Earth and Space Exploration at Arizona State University and lead author of the study.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">An insightful model</span></h4>
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The study also offers scientists new perspectives about the development of other planets and their potential to support life, the authors said. Earth-like planets in other solar systems may not all have access to asteroids loaded with water. The new study suggests these exoplanets could have obtained water through their system's own solar nebula.<br />
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"This model suggests that the inevitable formation of water would likely occur on any sufficiently large rocky exoplanets in extrasolar systems," Wu said. "I think this is very exciting."<br />
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Anat Shahar, a geochemist at the Carnegie Institution for Science, who was not involved with the study, noted the hydrogen fractionation factor, which describes how the deuterium-to-hydrogen ratio changes when the element dissolves in iron, is currently unknown and difficult to measure. For the new study, this property of hydrogen had to be estimated.<br />
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The new model, which fits in well with current research, could be tested once experiments reveal the hydrogen fractionation factor, Shahar said.<br />
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"This paper is a very creative alternative to what is an old problem," Shahar said. "The authors have done a good job of estimating what these different fractionation factors would be without having the experiments."</div>
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://news.agu.org/press-release/scientists-theorize-new-origin-story-for-earths-water/" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.agu.org/" rel="nofollow" target="_blank">American Geophysical Union</a>.</span></i></u></div>

Geoscientists Discover an Overlooked Source for Earth's Water

This view of Earth's horizon was taken by an Expedition 7 crew member onboard the International Space Station, using a wide-angle len...

The Lithosphere: Revolutionising Earth Tectonics

earth, Tectonic 8:34 PM

The Lithosphere: Revolutionising Earth Tectonics

Global shape index derived from GOCE satellite gravity data. Dome-ridge features characterise Earth’s oceans while valley to bowl feature...

New 12-Ton Jurassic dinosaur Was the Largest to Walk the Earth

dinosaur, Fossils 7:56 PM

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<tr><td style="text-align: center;"><a href="https://2.bp.blogspot.com/-1-W_WqlLR6k/W-B1NH07_sI/AAAAAAAAQiw/2bSLEYaZrTQll8m3heaDzn8ecIYrIROGACLcBGAs/s1600/dinosaur%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="New 12-Ton Jurassic dinosaur Was the Largest to Walk the Earth" border="0" data-original-height="789" data-original-width="1183" height="426" src="https://2.bp.blogspot.com/-1-W_WqlLR6k/W-B1NH07_sI/AAAAAAAAQiw/2bSLEYaZrTQll8m3heaDzn8ecIYrIROGACLcBGAs/s640/dinosaur%2B%25281%2529.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Jurassic dinosaur fossils seen at the Dinosaur National Monument. The newly-discovered dinosaur is believed to be from the Jurassic period, approximately 200 million years ago. (MIKE LYVERS/GETTY IMAGES)<br /></td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">The newly discovered species was massive but walked with a cat-like crouch.</span></h4>
A new species of a giant dinosaur has been found in South Africa's Free State Province. The plant-eating dinosaur, named Ledumahadi mafube, weighed 12 tonnes and stood about four metres high at the hips. Ledumahadi mafube was the largest land animal alive on Earth when it lived, nearly 200 million years ago. It was roughly double the size of a large African elephant.<br />
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A team of international scientists, led by University of the Witwatersrand (Wits) palaeontologist Professor Jonah Choiniere, described the new species in the journal Current Biology.<br />
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The dinosaur's name is Sesotho for "a giant thunderclap at dawn" (Sesotho is one of South Africa's 11 official languages and an indigenous language in the area where the dinosaur was found).<br />
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"The name reflects the great size of the animal as well as the fact that its lineage appeared at the origins of sauropod dinosaurs," said Choiniere. "It honours both the recent and ancient heritage of southern Africa."<br />
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Ledumahadi mafube is one of the closest relatives of sauropod dinosaurs. Sauropods, weighing up to 60 tonnes, include well-known species like Brontosaurus. All sauropods ate plants and stood on four legs, with a posture like modern elephants. Ledumahadi evolved its giant size independently from sauropods, and although it stood on four legs, its forelimbs would have been more crouched. This caused the scientific team to consider Ledumahadi an evolutionary "experiment" with giant body size.<br />
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Ledumahadi's fossil tells a fascinating story not only of its individual life history, but also the geographic history of where it lived, and of the evolutionary history of sauropod dinosaurs.<br />
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"The first thing that struck me about this animal is the incredible robustness of the limb bones," says lead author, Dr Blair McPhee. "It was of similar size to the gigantic sauropod dinosaurs, but whereas the arms and legs of those animals are typically quite slender, Ledumahadi's are incredibly thick. To me this indicated that the path towards gigantism in sauropodomorphs was far from straightforward, and that the way that these animals solved the usual problems of life, such as eating and moving, was much more dynamic within the group than previously thought."<br />
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The research team developed a new method, using measurements from the "arms" and "legs" to show that Ledumahadi walked on all fours, like the later sauropod dinosaurs, but unlike many other members of its own group alive at its time such as Massospondylus. The team also showed that many earlier relatives of sauropods stood on all fours, that this body posture evolved more than once, and that it appeared earlier than scientists previously thought.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-DzZLOGdCbQ0/W-B18Z0Jm1I/AAAAAAAAQi4/sML_ugosKEgUJWoEOYIU5su7su_TOT7pgCLcBGAs/s1600/Jurassic%2Bdinosaur%2Bfossils%2Bseen%2Bat%2Bthe%2BDinosaur%2BNational%2BMonument.%2BThe%2Bnewly-discovered%2Bdinosaur%2Bis%2Bbelieved%2Bto%2Bbe%2Bfrom%2Bthe%2BJurassic%2Bperiod%252C%2Bapproximately%2B200%2Bmillion%2Byears%2Bago.%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Ledumahadi mafube is the first of the giant sauropodomorphs of the Jurassic." border="0" data-original-height="878" data-original-width="878" height="400" src="https://1.bp.blogspot.com/-DzZLOGdCbQ0/W-B18Z0Jm1I/AAAAAAAAQi4/sML_ugosKEgUJWoEOYIU5su7su_TOT7pgCLcBGAs/s400/Jurassic%2Bdinosaur%2Bfossils%2Bseen%2Bat%2Bthe%2BDinosaur%2BNational%2BMonument.%2BThe%2Bnewly-discovered%2Bdinosaur%2Bis%2Bbelieved%2Bto%2Bbe%2Bfrom%2Bthe%2BJurassic%2Bperiod%252C%2Bapproximately%2B200%2Bmillion%2Byears%2Bago.%2B%25281%2529.jpg" title="" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ledumahadi mafube is the first of the giant sauropodomorphs of the Jurassic.</td></tr>
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"Many giant dinosaurs walked on four legs but had ancestors that walked on two legs. Scientists want to know about this evolutionary change, but amazingly, no-one came up with a simple method to tell how each dinosaur walked, until now," says Dr Roger Benson.<br />
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By analysing the fossil's bone tissue through osteohistological analysis, Dr Jennifer Botha-Brink from the South African National Museum in Bloemfontein established the animal's age.<br />
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"We can tell by looking at the fossilised bone microstructure that the animal grew rapidly to adulthood. Closely-spaced, annually deposited growth rings at the periphery show that the growth rate had decreased substantially by the time it died," says Botha-Brink. This indicates that the animal had reached adulthood.<br />
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"It was also interesting to see that the bone tissues display aspects of both basal sauropodomorphs and the more derived sauropods, showing that Ledumahadi represents a transitional stage between these two major groups of dinosaurs."<br />
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Ledumahadi lived in the area around Clarens in South Africa's Free State Province. This is currently a scenic mountainous area, but looked much different at that time, with a flat, semi-arid landscape and shallow, intermittently dry streambeds.<br />
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"We can tell from the properties of the sedimentary rock layers in which the bone fossils are preserved that 200 million years ago most of South Africa looked a lot more like the current region around Musina in the Limpopo Province of South Africa, or South Africa's central Karoo," says Dr Emese Bordy.<br />
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Ledumahadi is closely related to other gigantic dinosaurs from Argentina that lived at a similar time, which reinforces that the supercontinent of Pangaea was still assembled in the Early Jurassic. "It shows how easily dinosaurs could have walked from Johannesburg to Buenos Aires at that time," says Choiniere.<br />
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South Africa's Minister of Science and Technology Mmamoloko Kubayi-Ngubane says the discovery of this dinosaur underscores just how important South African palaeontology is to the world.<br />
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"Not only does our country hold the Cradle of Humankind, but we also have fossils that help us understand the rise of the gigantic dinosaurs. This is another example of South Africa taking the high road and making scientific breakthroughs of international significance on the basis of its geographic advantage, as it does in astronomy, marine and polar research, indigenous knowledge, and biodiversity," says Kubayi-Ngubane.<br />
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The research team behind Ledumahadi includes South African-based palaeoscientists, Dr Emese Bordy and Dr Jennifer Botha-Brink, from the University of Cape Town and the South African National Museum in Bloemfontein, respectively.<br />
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The project also had a strong international component with the collaboration of Professor Roger BJ Benson of Oxford University and Dr Blair McPhee, currently residing in Brazil.<br />
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"South Africa employs some of the world's top palaeontologists and it was a privilege to be able to build a working group with them and leading researchers in the UK," says Choiniere, who recently emigrated from the USA to South Africa. "Dinosaurs didn't observe international boundaries and it's important that our research groups don't either."<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(18)30993-X" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.wits.ac.za/" rel="nofollow" target="_blank">University of the Witwatersrand.</a></span></i></u></div>

New 12-Ton Jurassic dinosaur Was the Largest to Walk the Earth

Jurassic dinosaur fossils seen at the Dinosaur National Monument. The newly-discovered dinosaur is believed to be from the Jurassic perio...

First Fossil Lungs Found in Dinosaur-Era Bird

dinosaur, Fossils 5:12 PM

First Fossil Lungs Found in Dinosaur-Era Bird

Archaeorhynchus spathula was a beaked, feathered bird that lived 120 million years ago. A new fossil discovery suggests it had a respirat...

Deepest High-temperature Hydrothermal Vents Discovered in Pacific Ocean

earth, ocean 8:17 PM

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<tr><td class="tr-caption" style="text-align: center;">Hydrothermal Vent Chimeny. Photo: NOAA Ship Okeanos Explorer</td></tr>
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In spring 2015, MBARI researchers discovered a large, previously unknown field of hydrothermal vents in the Gulf of California, about 150 kilometers (100 miles) east of La Paz, Mexico. Lying more than 3,800 meters (12,500 feet) below the surface, the Pescadero Basin vents are the deepest high-temperature hydrothermal vents ever observed in or around the Pacific Ocean.<br />
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They are also the only vents in the Pacific known to emit superheated fluids rich in both carbonate minerals and hydrocarbons. The vents have been colonized by dense communities of tubeworms and other animals unlike any other known vent communities in the in the eastern Pacific.<br />
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Like another vent field in the Gulf that MBARI discovered in 2012, the Pescadero Basin vents were initially identified in high-resolution sonar data collected by an autonomous underwater vehicle (AUV). MBARI's yellow, torpedo-shaped seafloor-mapping AUV spent two days flying about 50 meters above the bottom of the Basin, using sound beams to map the depth and shape of the seafloor.<br />
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The AUV team, led by MBARI engineer David Caress, pored over the detailed bathymetric map they created from the AUV data and saw a number of mounds and spires rising up from the seafloor. Data from the AUV also showed slightly warmer water over some of the spires, which implied that they might be active hydrothermal-vent chimneys.<br />
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A team of geologists led by David Clague then used a tethered underwater robot, the remotely operated vehicle (ROV) Doc Ricketts, to dive down to the seafloor, fly around the vents, and collect video and samples of rocks and hot water spewing from the chimneys.<br />
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Reflecting on the discovery, Clague commented, 'Before the AUV survey of Pescadero Basin, all we knew was that this area was really deep and filled with sediment. I was hoping to find a few outcrops of lava on the seafloor. But we got lucky. The vent field was right on the edge of our survey area, along a fault at the western edge of the basin.'<br />
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The AUV and ROV dives showed that the new field extends for at least 400 meters (one quarter mile) along this fault. Within this area the researchers found at least three active hydrothermal chimneys up to 12 meters (40 feet) tall, as well as dozens of low mounds that are most likely collapsed chimneys.<br />
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After his ROV dive, Clague noted, 'This site was not at all what I was expecting.' For one thing, the fragments of chimneys that the ROV brought back to the surface were quite different from those collected at other vents in the area. The Pescadero chimneys consisted entirely of light-colored carbonate minerals instead of the dark sulfide minerals that are abundant in hydrothermal chimneys elsewhere in the Gulf.<br />
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The Pescadero Basin is only the second place in the world where carbonate chimneys (instead of ones made primarily of sulfides) have been found in the deep sea. The other known location is the 'Lost City' vent field in the middle of the Atlantic Ocean, at a spot on the Mid-Atlantic Ridge.<br />
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The geologists also noticed that their rock samples smelled like diesel. They hypothesize that hot hydrothermal fluids migrating upward through the thick sediments of the Pescadero Basin 'cook' organic matter in the sediment, converting it into petroleum-like hydrocarbons -- a process that has been observed at several other vents in the Pacific. Hydrocarbons may provide nutrition for the unusual microbes that thrive at these vents.<br />
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After Clague's initial ROV dive, MBARI biologist Robert Vrijenhoek made three follow-up dives in the Pescadero Basin. His goal was to determine how and why animal communities at the Pescadero vents differed from those at other vent fields in the Gulf. Clague's and Vrijenhoek's dives revealed at least three different types of hydrothermal vents in the southern Gulf of California -- black smokers, carbonate chimneys, and hydrothermal seeps. Each environment supports its own unique animal community.<br />
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Black smokers form in active volcanic areas. One such area is on the Alarcón Rise, about 160 kilometers (100 miles) south of the Pescadero Basin, where MBARI researchers discovered several hydrothermal fields in 2012. On the Alarcón Rise, massive, dark-colored sulfide chimneys rise more than 37 meters (120 feet) above the lava-covered seafloor.<br />
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These chimneys gush extremely hot fluids (over 350 degrees Celsius, 660 degrees Fahrenheit) rich in heavy metals and sulfides. When the superheated fluids come in contact with near-freezing seawater, these minerals precipitate, forming dark, smoke-like plumes of particles. The 'black smoker' chimneys are often colonized by giant tubeworms in the genus Riftia, which grow over two meters (six feet) long, as well as limpets, crabs, squat lobsters, and Alvinella palmworms.<br />
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In contrast, the carbonate chimneys in the Pescadero Basin emerge from a flat, muddy seafloor, and are smaller and more delicate than black smokers. They emit fluids that are slightly cooler (250-290 degrees Celsius) and do not form dark, smoke-like plumes. The Pescadero Basin fluids are, however, rich in oil-like hydrocarbons that form dark, oily crusts on the light colored carbonate chimneys. They also support a very different group of animals, including dense colonies of tubeworms in the genus Oasisia.<br />
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In the third type of vent environment, 'hydrothermal seeps,' much cooler (less than 30-60 degrees Celsius) water trickles out of lava flows interleaved with seafloor mud. These seeps support an entirely different community of animals, including anemones, tubeworms in the genera Lamellibrachia and Escarpia, and broad, white mats of bacteria. In contrast to the Pescadero and Alarcón vents, each of which hosted a single species of deep-sea clams, the seeps support at least four different types of clams.<br />
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One thing that all of these communities have in common is that the dominant tubeworms and clams host specialized intracellular bacteria (symbionts) that allow these animals to exploit potentially toxic chemicals in the vent fluids as sources of nutrition. Vrijenhoek and his collaborators are trying to figure out if the different vent communities in the Gulf are controlled by differences in water depth, geochemistry, symbiotic bacteria, or perhaps other unanticipated factors.<br />
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The discovery of the Pescadero Basin hydrothermal field is just the latest example of how MBARI's extensive use of underwater robotics has accelerated the pace of scientific discovery in the deep sea. As Vrijenhoek noted, 'In the 1990s, following the discovery of plumes of warm water over the Mid-Atlantic Ridge, researchers from four countries searched for seven years to find what eventually became known as the 'rainbow vent field.' They were limited by inaccurate and imprecise bathymetric maps. This spring it took us only two days to do the same thing in the Pescadero Basin, using MBARI's high-precision seafloor-mapping AUV.'<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://www.mbari.org/news/news_releases/2015/pescadero/pescadero-release.html" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.mbari.org/" rel="nofollow" target="_blank">Monterey Bay Aquarium Research Institute</a>.</span></i></u></div>

Deepest High-temperature Hydrothermal Vents Discovered in Pacific Ocean

Hydrothermal Vent Chimeny. Photo: NOAA Ship Okeanos Explorer In spring 2015, MBARI researchers discovered a large, previously unknown...

Ancient Crystals Shed Light on Earth’s Earliest History

Earth History, Geochemistry 8:03 PM

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<tr><td style="text-align: center;"><a href="https://3.bp.blogspot.com/-6ktd5Ye1tq8/W9ndUVKiHiI/AAAAAAAAQhY/26nXL-3jidIjZQNqu1kdLKgzYxktsS2qgCLcBGAs/s1600/Zonal%2Bcrystal%2Bof%2Bzircon.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Ancient Crystals Shed Light on Earth’s Earliest History" border="0" data-original-height="905" data-original-width="1248" height="464" src="https://3.bp.blogspot.com/-6ktd5Ye1tq8/W9ndUVKiHiI/AAAAAAAAQhY/26nXL-3jidIjZQNqu1kdLKgzYxktsS2qgCLcBGAs/s640/Zonal%2Bcrystal%2Bof%2Bzircon.jpg" title="" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Zonal crystal of zircon. Photo: Petr Hykš</td></tr>
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To geologists, Earth’s early history is somewhat of a black box. Volcanoes, magma seas, and meteorite impacts defined our planet’s surface from its formation, 4.6 billion years ago, until the earliest rock record appeared roughly 600 million years later.<br />
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Hardly any original material survived this dynamic period, known as the Hadean Eon, so scientists have little recourse to test their theories.<br />
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Preston Cloud initially proposed the Hadean eon in 1972. He suggested that the first 600 million years of Earth’s history would have been a time of hellish conditions with abundant volcanism. Surface conditions were unlikely to have allowed for the preservation of a rock record, much less the rise of life.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Near Sole Survivors</span></h4>
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Zircon crystals, which are dense and relatively robust against all sorts of weathering processes, are among the few fragments that survived this violent period.<br />
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“That’s why, throughout the world, the oldest minerals that have ever been found are almost exclusively zircons,” explains Ben Byerly, a geochemist and postdoctoral researcher at UC Santa Barbara, and lead author of a paper on the discovery, which appears in Geology.<br />
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Byerly has spent over a decade studying the geology of the Barberton greenstone belt deposit in the Barberton Mountains. Not only is this deposit incredibly old, but its rocks are relatively unaltered compared to many other rocks of similar age, which means many of their characteristics are really well preserved, Byerly says.<br />
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Researchers collected samples from sedimentary layers and separated small grains of zircon from the rest of the rock. Zircons naturally contain uranium impurities, which scientists can use to date a crystal’s formation.<br />
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Since uranium decays into lead at a well-known rate, the researchers simply needed to determine the concentration of lead built up within the crystal to determine how long ago it formed.<br />
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What’s more, the scientists can be sure that all the lead in the crystal came from radioactive decay because zircons naturally reject lead during their formation.<br />
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While running routine analyses on one sedimentary layer, Byerly and colleagues realized that several of the zircons in the sample dated to the Hadean eon. After redoubling their efforts, the team found 11 zircon grains that formed more than 4 billion years ago.<br />
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“This is only the second place on Earth where so many ancient crystals have been found,” Byerly says.<br />
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Most of the zircons, though, formed 3.4 billion years ago, and not just in the South African deposit. Hadean material in Australia also contains a preponderance of zircons of this age. “So this 3.4 billion-year-old event is potentially something global,” Byerly says.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Volcanoes and Meteorites</span></h4>
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Earth’s early history is replete with active volcanism and heavy bombardment by meteorites. Both of these processes could have contributed to the formation of zircons, and increased activity may be responsible for the high number of crystals that formed 3.4 billion years ago.<br />
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Researchers have already found evidence of about 10 enormous meteorite impacts associated with other sedimentary layers in the Barberton greenstone belt, from 3.5 to 3.2 billion years ago.<br />
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Models suggest each impact could have boiled away dozens to hundreds of meters of ocean water and vaporized vast swaths of the planet’s surface. Several of these meteorites would have outclassed the rock that killed off the non-avian dinosaurs.<br />
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“Potentially, the very largest ones could have completely sterilized the Earth,” Byerly says.</div>
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<span style="font-family: "georgia" , "times new roman" , serif;">Lava Flows</span></h4>
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Understanding the conditions of early Earth revolves around deciphering in what kind of rocks these zircons formed. Analyzing the isotopes and trace elements in the zircons, as well as other mineral grains in the formation, will provide scientists with more insights in this regard.<br />
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Byerly and his mentor Matt Jackson, a professor of earth science at UC Santa Barbara, are developing methods to measure minute quantities of strontium, neodymium and lead for isotopic analyses. They are currently focused on minerals from the Earth’s crust and mantle, including 3.3 billion-year-old lava flows from the Barberton greenstone belt.<br />
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“By studying these really old rocks, and especially by studying these really old zircons, we can help to answer questions like when did plate tectonics start? And when did the first continents form?” Byerly says.</div>
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<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://news.vanderbilt.edu/2018/10/11/volcano-researcher-learns-how-earth-builds-supereruption-feeding-magma-systems/" rel="nofollow" target="_blank">materials </a>provided by<a href="https://www.vanderbilt.edu/" rel="nofollow" target="_blank"> Vanderbilt University.</a></span></u></i></div>
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Ancient Crystals Shed Light on Earth’s Earliest History

Zonal crystal of zircon. Photo: Petr Hykš To geologists, Earth’s early history is somewhat of a black box. Volcanoes, magma seas, ...

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5,655-carat Emerald With 'Golden Green Hue' Discovered

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