Obsidian : What is obsidian? Why obsidian is black?

August 17, 2019

What is Obsidian?

Obsidian Rock

Color: Deep black or blackish green
Fracture: Conchoidal
Mohs scale hardness: 5 – 6
Luster: Vitreous
Specific gravity: c. 2.4
Optical properties: Translucent

Obsidian is a volcanic glass that occurs naturally as an extrusionary igneous rock.

Obsidian is a massive glass of volcanoes. This word is’ huge,’ but it does mean in geology that stone (obsidian is rocky, not a mineral) is homogeneous, though this is connected to geologies. Laying, slitting, leavening, phenocrysts, etc. is lacking. It is simply an unconditional piece of volcanic glass. Obsidian solidification (on earth) in most instances was subaerial. Underwater volcanic glass has alternative names such as tachyllite and hyaloclastic.

The volcanic glass and obsidian are therefore not synonymous, although you can often freely use both terms. You certainly do not use “volcanic glass” rather than “obsidian,” but be careful about it—volcanic glass isn’t always obsidian.

Volcano glass is an igneous rock made up of a magmatic content mainly uncrypted. Most of it is not crystallized because the crystals had two difficult problems which restricted their growth. It’s time the first. Large crystals have to develop for a long moment. When viscous magma is removed from a volcano and cools quickly, there’s very little. I gave a subtle indication of what might be the second issue. It is the viscosity of magma / lava. The crystals are very difficult to form if the magmatic body is thick and viscous, because they don’t have new material, when almost nothing can move inside the magma body.

So obsidian forms from viscous magma only? Often yes, but not always. The structure of most obsidians is rhyolitic. The thickest lava has the largest concentration of silica. Why does this matter? Since silica polymerizes magma. There are many bridges (chemical connections) between silica oxygen anions (SiO2), which is why it is so difficult to relocate this magma. If the water has many electrons (cations), it is less viscous, because the frame system of silica is broken by these cations.

How Obsidian is Formed?

Obsidian is created when the volcano’s felsic lava cools quickly with minimal crystal growth. The chemicals (hodium silica content) produce a elevated viscosity that shapes a natural glass from lava when rapidly drying. The chemical composition is often discovered on the edges of rhyolitic lava flows recognized as obsidian flows. The absence of crystal growth is explained by the inhibition of atomic diffusion by this high-viscous lava. Obsidian is difficult, fragile and amorphous and therefore has strong corners of fractures. The instruments for slicing and piercing were previously used and were used as operative scalpel blades experimentally.

The obsidian is the rock created by fast-cooled lava, the material father. Extensive obsidian formation can happen if felsic magma quickly recools on the corners of a volcanic dome or felsic lava stream, or if lava cools during abrupt water or wind touch. Obsidian can be intrusive when felsic lava cools on the edges of a deck.

Obsidian consists of approximately 70% or more of the silicone (silicone dioxide) that has been uncristallised. It is like granite and rhyolite, which were also initially frozen, chemically. As obsidian is not mineral crystals, it is not a real “stone” technically obsidian. It is actually a congealed fluid with small quantities of microscopic and impure microscopy. Obsidian with a typical hardness of 5 to 5.5 is comparatively gentle on the level of mineral hardness. In contrast, quartz (silicium dioxide crystallized) is of 7.0 hardness.

Why Obsidian is Black?

Pure obsidian is generally black, although the colour differs with the existence of impurity. The jade could be light gray to black with iron and other transformation components. The majority of black obsidians are magnetite-nanoinclusions, iron oxide. Very few obsidian specimens are almost colorless. In some rocks, the incorporation of the mineral cristobalitis in the black glass of tiny, yellow, radially grouped rocks produces a blotchy (snowflaking) image.

Obsidian can include patterns of gas bubbles from the lava flow that align with layers created during molten rock before cooling. These bubbles could generate exciting impacts like a golden blade (obsidian blade). The inclusion of magnetite nanoparticles, which create a thin-film interference, causes an iridescent, rainbow-like shine. Mexican colorful rainbow obsidian contains hedenbergite oriented nanorods which cause rainbow strewning effects via interference with thin films.

The various colors of obsidian are a result of several factors. There are very few clear obsidian types, or microscopic mineral crystals. Obsidian red or brown usually results in small crystals or hematite or limonite (iron oxide) inclusions. The jet-black types of obsidian are probable to generate abundant microscopic crystals of minerals such as magnet, hornblende, pyroxene, plagioclase, and biotites in combination with smaller pieces of rocken. The distinctive blue, green, violet or bronze colours of the rainbow obsidian may be obtained from a microscope of multiple feldspar kinds.

Where Obsidian is Found?

Obsidian can be discovered in places with rhyolitical temperatures. You can find it in Argentina, Australia, Chile, Azerbaijan, Armenia, Guatemala, Iceland, Mexico, New Zealand, Iceland, Peru, Greece, El Salvador, Turkey, Kenya, Mexico, Peru and New Zealand. In Cascade Range of the west of north America and in the south of California’s Sierra Nevada, Obsidian streams can be discovered within Newberry Volcano calderas and Medicine Lake Volcano. Yellowstone National Park is situated between Mammoth Hot Springs and the Norris Geyser Basin and has an obsidian mountain ranges and reservoirs in many other Western US States such as Arizona, Colorado, New Mexico, Texas, Utah, Washington, Oregon, and Idaho. The southern countries of Virginia, as well as Pennsylvania and North Carolina are also subject to obsidian.

In the main Mediterranean there are only four significant deposits: Lipari, Pantelleria, Palmarola and Monte Arci. Milos and Gyali were former suppliers in the Aegean.

The most significant springs in Central Anatolia, one of the main sources in the prehistorical Middle East, were the city Acıgöl and the Göllü Dağ volcano.

Superdeep diamonds confirm ancient reservoir deep under Earth’s surface

August 17, 2019

Diamonds from the Juina area: most of these are superdeep diamonds. Credit: Graham Pearson

Analyses show that gases found in microscopic inclusions in diamonds come from a stable subterranean reservoir at least as old as the Moon, hidden more than 410 km below sea level in the Earth’s mantle.

Scientists have long suspected that an area of the Earth’s mantle, somewhere between the crust and the core, contains a vast reservoir of rock, comparatively undisturbed since the planet’s formation. Until now, there has been no firm proof if or where it exists. Now an international group of scientists has measured helium isotopes contained in superdeep diamonds brought to the surface by violent volcanic eruptions, to detect the footprints of this ancient reservoir. This work will be presented to scientists for the first time on Friday 23rd August at the Goldschmidt conference in Barcelona, after publication today (15 August) in the journal Science.

After the formation of the Earth, violent geological activity and extra-terrestrial impacts disrupted the young planet, meaning that almost nothing of the Earth’s original structure remains. Then in the 1980’s geochemists noted that in some basalt lavas from particular locations the ratio of the helium 3 to helium 4 isotope was higher than expected, mirroring the isotope ratio found in extremely old meteorites which had fallen to Earth. This indicates that the lava had carried the material from some kind of reservoir deep in the Earth, with a composition which hasn’t changed significantly in the last 4 billion years. “This pattern has been observed in “Ocean Island Basalts,” which are lavas coming to the surface from deep in the Earth, and form islands such as Hawaii and Iceland” said research leader Dr. Suzette Timmerman, from the Australian National University. “The problem is that although these basalts are brought to the surface, we only see a glimpse of their history. We don’t know much about the mantle where their melts came from.”

To address this problem, Timmerman’s team looked at helium isotope ratios in superdeep diamonds. Most diamonds are formed between 150 to 230 km below the Earth’s crust, before being carried to the surface by melts. Very occasionally some ‘superdeep’ diamonds (created between 230 and 800 km below the Earth’s surface) are brought to the surface. These superdeep diamonds are recognizably different from normal diamonds.

Suzette Timmerman said, “Diamonds are the hardest, most indestructible natural substance known, so they form a perfect time capsule that provides us a window into the deep Earth. We were able to extract helium gas from twenty-three super-deep diamonds from the Juina area of Brazil. These showed the characteristic isotopic composition that we would expect from a very ancient reservoir, confirming that the gases are remnants of a time at or even before the Moon and Earth collided. From the geochemistry of the diamonds, we know that they formed in an area called the “transition zone,” which is between 410 and 660 km below the surface of the Earth. This means that this unseen reservoir, left over from the Earth’s beginnings, must be in this area or below it.

“Questions remain about the form of this reservoir; is it a large single reservoir, or are there multiple smaller ancient reservoirs? Where exactly is the reservoir? What is the complete chemical composition of this reservoir? But with this work, we are beginning to home in on what is probably the oldest remaining comparatively undisturbed material on Earth,” she says.

Commenting, Professor Matthew Jackson (University of California, Santa Barbara) said, “There has been a lot of work focused on identifying the location of primordial reservoirs in the deep Earth. So this is an interesting result, with a lot of potential to “map out” where elevated 3He/4He domains are located in the Earth’s deep interior. Helium can diffuse rapidly at mantle conditions, so it will be important to evaluate whether the ancient helium signature reflects compositions trapped at diamond-formation depths, or the composition of the host lava that transported to diamonds to the surface. This work is an important step towards understanding these reservoirs, and points the way to further research.”

Reference:
S. Timmerman el al., “Primordial and recycled helium isotope signatures in the mantle transition zone,” Science (2019). science.sciencemag.org/cgi/doi … 1126/science.aax5293

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

Dinosaur brains from baby to adult

August 17, 2019

Head posture if the lateral (horizontal) semi-circular canal is parallel to the ground, in hatching (A), juvenile (B) and adult (C) Psittacosaurus lutjiatunensis. Images not to scale. Credit: Claire Bullar and IVPP.

New research by a University of Bristol palaeontology post-graduate student has revealed fresh insights into how the braincase of the dinosaur Psittacosaurus developed and how this tells us about its posture.

Psittacosaurus was a very common dinosaur in the Early Cretaceous period — 125 million years ago — that lived in eastern Asia, especially north-east China.

Hundreds of samples have been collected which show it was a beaked plant-eater, an early representative of the Ceratopsia, which had later relatives with great neck frills and face horns, such as Triceratops.

The babies hatched out as tiny, hamster-sized beasts and grew to two metres long as adults.

As they grew, the brain changed in shape, from being crammed into the back of the head, behind the huge eyes in the hatchling, to being longer, and extending under the skull roof in the adults.

The braincase also shows evidence for a change in posture as the animals grew. There is good evidence from the relative lengths of the arms and legs, that baby Psittacosaurus scurried about on all fours, but by the age of two or three, they switched to a bipedal posture, standing up on their elongate hind legs and using their arms to grab plant food.

Claire Bullar from the University of Bristol’s School of Earth Sciences led the new research which has been published this week in PeerJ.

She said: “I was excited to see that the orientation of the semi-circular canals changes to show this posture switch.

“The semi-circular canals are the structures inside our ears that help us keep balance, and the so-called horizontal semi-circular canal should be just that — horizontal — when the animal is standing in its normal posture.

“This is just what we see, with the head of Psittacosaurus pointing down and forwards when it was a baby — just right for moving on all-fours. Then, in the teen or adult, we see the head points exactly forwards, and not downwards, just right for a biped.”

Co-supervisor Dr Qi Zhao from the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) in Beijing, where the specimens are housed, added: “It’s great to see our idea of posture shift confirmed, and in such a clear-cut way, from the orientation of the horizontal ear canal.

“It’s also amazing to see the results of high-quality CT scanning in Beijing and the technical work by Claire to get the best 3D models from these scan data.”

Professor Michael Ryan of Carleton University, Ottawa, Canada, another collaborator, said: “This posture shift during growth from quadruped to biped is unusual for dinosaurs, or indeed any animal. Among dinosaurs, it’s more usual to go the other way, to start out as a bipedal baby, and then go down on all fours as you get really huge.

“Of course, adult Psittacosaurus were not so huge, and the shift maybe reflects different modes of life: the babies were small and vulnerable and so probably hid in the undergrowth, whereas bipedalism allowed the adults to run faster and escape their predators.”

Professor Michael Benton, also from the University of Bristol’s School of Earth Sciences and another collaborator, added: “This is a great example of classic, thorough anatomical work, but also an excellent example of international collaboration.

“The Bristol Palaeobiology Research Group has a long-standing collaboration with IVPP, and this enables the mix of excellent specimens and excellent research.

“Who would have imagined we could reconstruct posture of dinosaurs from baby to adult, and with multiple lines of evidence to confirm we got it right.”

Reference:
Claire M. Bullar, Qi Zhao, Michael J. Benton, Michael J. Ryan. Ontogenetic braincase development in Psittacosaurus lujiatunensis (Dinosauria: Ceratopsia) using micro-computed tomography. PeerJ, 2019; 7: e7217 DOI: 10.7717/peerj.7217

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

Ancient feces reveal how ‘marsh diet’ left Bronze Age Fen folk infected with parasites

August 17, 2019

Microscopic eggs of fish tapeworm (left), giant kidney worm (centre), and Echinostoma worm (right) from the Must Farm excavation. Black scale bar represents 20 micrometres. Credit: Marissa Ledger

New research published today in the journal Parasitology shows how the prehistoric inhabitants of a settlement in the freshwater marshes of eastern England were infected by intestinal worms caught from foraging for food in the lakes and waterways around their homes.

The Bronze Age settlement at Must Farm, located near what is now the fenland city of Peterborough, consisted of wooden houses built on stilts above the water. Wooden causeways connected islands in the marsh, and dugout canoes were used to travel along water channels.

The village burnt down in a catastrophic fire around 3,000 years ago, with artefacts from the houses preserved in mud below the waterline, including food, cloth, and jewellery. The site has been called “Britain’s Pompeii.”

Also preserved in the surrounding mud were waterlogged “coprolites” — pieces of human faeces — that have now been collected and analysed by archaeologists at the University of Cambridge. They used microscopy techniques to detect ancient parasite eggs within the faeces and surrounding sediment.

Very little is known about the intestinal diseases of Bronze Age Britain. The one previous study, of a farming village in Somerset, found evidence of roundworm and whipworm: parasites spread through contamination of food by human faeces.

The ancient excrement of the Anglian marshes tells a different story. “We have found the earliest evidence for fish tapeworm, Echinostoma worm, and giant kidney worm in Britain,” said study lead author Dr Piers Mitchell of Cambridge’s Department of Archaeology.

“These parasites are spread by eating raw aquatic animals such as fish, amphibians and molluscs. Living over slow-moving water may have protected the inhabitants from some parasites, but put them at risk of others if they ate fish or frogs.”

Disposal of human and animal waste into the water around the settlement likely prevented direct faecal pollution of the fenlanders’ food, and so prevented infection from roundworm — the eggs of which have been found at Bronze Age sites across Europe.

However, water in the fens would have been quite stagnant, due in part to thick reed beds, leaving waste accumulating in the surrounding channels. Researchers say this likely provided fertile ground for other parasites to infect local wildlife, which — if eaten raw or poorly cooked — then spread to village residents.

“The dumping of excrement into the freshwater channel in which the settlement was built, and consumption of aquatic organisms from the surrounding area, created an ideal nexus for infection with various species of intestinal parasite,” said study first author Marissa Ledger, also from Cambridge’s Department of Archaeology.

Fish tapeworms can reach 10m in length, and live coiled up in the intestines. Heavy infection can lead to anemia. Giant kidney worms can reach up to a metre in length. They gradually destroy the organ as they become larger, leading to kidney failure. Echinostoma worms are much smaller, up to 1cm in length. Heavy infection can lead to inflammation of the intestinal lining.

“As writing was only introduced to Britain centuries later with the Romans, these people were unable to record what happened to them during their lives. This research enables us for the first time to clearly understand the infectious diseases experienced by prehistoric people living in the Fens,” said Ledger.

The Cambridge team worked with colleagues at the University of Bristol’s Organic Chemistry Unit to determine whether coprolites excavated from around the houses were human or animal. While some were human, others were from dogs.

“Both humans and dogs were infected by similar parasitic worms, which suggests the humans were sharing their food or leftovers with their dogs,” said Ledger.

Other parasites that infect animals were also found at the site, including pig whipworm and Capillaria worm. It is thought that they originated from the butchery and consumption of the intestines of farmed or hunted animals, but probably did not cause humans any harm.

The researchers compared their latest data with previous studies on ancient parasites from both the Bronze Age and Neolithic. Must Farm tallies with the trend of fewer parasite species found at Bronze Age compared with Neolithic sites.

“Our study fits with the broader pattern of a shrinking of the parasite ecosystem through time,” said Mitchell. “Changes in diet, sanitation and human-animal relationships over millennia have affected rates of parasitic infection.” Although he points out that infections from the fish tapeworm found at Must Farm have seen a recent resurgence due to the popularity of sushi, smoked salmon and ceviche.

“We now need to study other sites in prehistoric Britain where people lived different lifestyles, to help us understand how our ancestors’ way of life affected their risk of developing infectious diseases,” added Mitchell.

The Must Farm site is an exceptionally well-preserved settlement dating to 900-800 BC (the Late Bronze Age). The site was first discovered in 1999. The Cambridge Archaeological Unit carried out a major excavation between 2015 and 2016, funded by Historic England and Forterra Building Products Ltd.

Reference:
Marissa L. Ledger, Elisabeth Grimshaw, Madison Fairey, Helen L. Whelton, Ian D. Bull, Rachel Ballantyne, Mark Knight, Piers D. Mitchell. Intestinal parasites at the Late Bronze Age settlement of Must Farm, in the fens of East Anglia, UK (9th century B.C.E.). Parasitology, 2019; 1 DOI: 10.1017/S0031182019001021

Note: The above post is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons License.

Magnified Sand : Magnified Photos Shows How Sand Looks like

August 14, 2019

Magnified-sand grains Sand that is magnified up to 300 times

Magnified Sand

Comparing something to a grain of sand is generally meant to imply it’s tiny or meaningless, but the amazing images of Dr. Gary Greenberg produced using a microlens are aimed at turning this stereotype on his head. His pictures of tiny grains of up to 300-fold magnified colourful rocks show it under a microscope can be a hypocrisy.

Depending on where it comes from, Sand structure can differ dramatically. The Hawaiian coastal beach sands, where Dr. Greenberg is situated, are the topics of his incredible microphotography. The tiny rocks in his pictures are full of vestiges of different big and small tropical ocean species. The sand on other shores may include a completely distinct collection of stones, minerals and organic matter based on the temperature, surfing circumstances and marine environment.

The grains originate from various coasts all over the globe, from Okinawa, from Japan to Maui, from Hawaii to Smith Mountain Lake, from Va. Each fragment is distinctive and extremely lovely in personality.

Greenberg’s website explains that he spent his life “revealing the secret beauty of nature.” Using high-quality microscopes, he creates “spectacular worldscapes beyond our daily perception— worlds where reality is seen as abstract form and colour, motion and texture.”

I am fascinated by the complexity and individuality produced by a mixture of nature and the frequent crashing of surfing on a beach every moment I look through my microscope.’

Professor Greenberg, who searches through thousands of small stones with acupuncture instruments to discover and organize the most ideal samples, then utilizes a painful method to produce his pictures.

He’s been looking for notable sand grains like these to photograph the globe for five years.

He said:’ Extreme close-up photography usually provides a very small field depth so I had to create a fresh method for making the photos I wished.

I take dozens of pictures at separate focal points and then add them to create my images using software.

Even though the images look easy, it may take hours to photograph each grain of it in a manner I am pleased with.

Magnified sand grains Sand that is magnified up to 300 times

1 of 11

Credit: Sand Grains

Jurassic world of volcanoes found in central Australia

August 14, 2019

Volatile elements in magma, primarily water, drive explosive volcanic eruptions, like this eruption of Anak Krakatau in Lampung, Indonesia, in 2018. Experimental geochemists from Washington University in St. Louis have discovered compelling evidence that magmas may be wetter than once thought. Credit: Shutterstock

An international team of subsurface explorers from the University of Adelaide in Australia and the University of Aberdeen in Scotland have uncovered a previously undescribed ‘Jurassic World’ of around 100 ancient volcanoes buried deep within the Cooper-Eromanga Basins of central Australia.

The Cooper-Eromanga Basins in the north-eastern corner of South Australia and south-western corner of Queensland is Australia’s largest onshore oil and gas producing region of Australia. But, despite about 60 years of petroleum exploration and production, this ancient Jurassic volcanic underground landscape has gone largely unnoticed.

Published in the journal Gondwana Research, the researchers used advanced subsurface imaging techniques, analogous to medical CT scanning, to identify the plethora of volcanic craters and lava flows, and the deeper magma chambers that fed them. They’ve called the volcanic region the Warnie Volcanic Province, with a nod to Australian cricket legend Shane Warne.

The volcanoes developed in the Jurassic period, between 180 and 160 million years ago, and have been subsequently buried beneath hundreds of meters of sedimentary — or layered — rocks.

The Cooper-Eromanga Basins are now a dry and barren landscape but in Jurassic times, the researchers say, would have been a landscape of craters and fissures, spewing hot ash and lava into the air, and surrounded by networks of river channels, evolving into large lakes and coal-swamps.

“While the majority of Earth’s volcanic activity occurs at the boundaries of tectonic plates, or under the Earth’s oceans, this ancient Jurassic world developed deep within the interior of the Australian continent,” says co-author Associate Professor Simon Holford, from the University of Adelaide’s Australian School of Petroleum.

“Its discovery raises the prospect that more undiscovered volcanic worlds reside beneath the poorly explored surface of Australia.”

The research was carried out by Jonathon Hardman, then a PhD student at the University of Aberdeen, as part of the Natural Environment Research Council Centre for Doctoral Training in Oil and Gas.

The researchers say that Jurassic-aged sedimentary rocks bearing oil, gas and water have been economically important for Australia, but this latest discovery suggests a lot more volcanic activity in the Jurassic period than previously supposed.

“The Cooper-Eromanga Basins have been substantially explored since the first gas discovery in 1963,” says co-author Associate Professor Nick Schofield, from the University of Aberdeen’s Department of Geology and Petroleum Geology.

“This has led to a massive amount of available data from underneath the ground but, despite this, the volcanics have never been properly understood in this region until now. It changes how we understand processes that have operated in Earth’s past.”

The researchers have named their discovery the Warnie Volcanic Province after one of the drill holes that penetrated Jurassic volcanic rocks (Warnie East-1), itself named after a nearby waterhole), but also in recognition of the explosive talent of former Australian cricketer Shane Warne.

“We wrote much of the paper during a visit to Adelaide by the Aberdeen researchers, when a fair chunk was discussed and written at Adelaide Oval during an England vs Cricket Australia XI match in November 2017. Inspired by the cricket, we thought Warnie a good name for this once fiery region,” says Associate Professor Holford.

Reference:
Jonathon P.A. Hardman, Simon P. Holford, Nick Schofield, Mark Bunch, Daniel Gibbins. The Warnie volcanic province: Jurassic intraplate volcanism in Central Australia. Gondwana Research, 2019; 76: 322 DOI: 10.1016/j.gr.2019.06.012

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

Researchers study largest impact crater in the US, buried for 35 million years

August 14, 2019

The 21 shocked and unshocked zircon crystals dated in this study were separated from this ~30 cubic centimeters of unconsolidated late Eocene sediment obtained from Ocean Drilling Project site 1073, hole A. Credit: Biren/ASU

About 35 million years ago, an asteroid hit the ocean off the East Coast of North America. Its impact formed a 25-mile diameter crater that now lies buried beneath the Chesapeake Bay, an estuary in Virginia and Maryland. From this impact, the nearby area experienced fires, earthquakes, falling molten glass droplets, an air blast and a devastating tsunami.

While the resulting “Chesapeake Bay impact crater” is now completely buried, it was discovered in the early 1990s by scientific drilling. It now ranks as the largest known impact crater in the U.S., and the 15th largest on Earth.

When the asteroid hit, it also produced an impact ejecta layer, which includes tektites (natural glass formed from debris during meteorite impacts) and shocked zircon crystals which were thrown out of the impact area. Scientists refer to this layer as the “North American tektite strewn field,” which covers a region of roughly 4 million square miles, about 10 times the size of Texas. Some ejecta landed on land while the rest immediately cooled on contact with seawater and then sank to the ocean floor.

A team of researchers, including Arizona State University School of Earth and Space Exploration scientist and lead author Marc Biren, along with co-authors Jo-Anne Wartho, Matthijs Van Soest and Kip Hodges, has obtained drilling samples from the Ocean Drilling Project site 1073 and dated them with the “uranium-thorium-helium technique” for the first time.

Their research was recently published in the international journal Meteoritics & Planetary Science.

“Determining accurate and precise ages of impact events is vital in our understanding of the Earth’s history,” Biren said. “In recent years, for example, the scientific community has realized the importance of impact events on Earth’s geological and biological history, including the 65 million years old dinosaur mass extinction event that is linked to the large Chicxulub impact crater.”

The team studied zircon crystals in particular because they preserve evidence of shock metamorphism, which is caused by shock pressures and high temperatures associated with impact events. The dated crystals were tiny, about the thickness of a human hair.

“Key to our investigation were zircon — or to be more precise: zirconium silicate — crystals that we found in the oceanic sediments of a borehole, which is located almost 400 kilometers (250 miles) northeast of the impact site, in the Atlantic Ocean,” says co-author Wartho, who began the study when she was a lab manager at the Mass Spectrometry Lab at ASU.

For this study, Biren worked with co-authors Wartho (now working at GEOMAR Helmholtz Centre for Ocean Research Kiel), Van Soest and Hodges to prepare samples for analysis and to date zircon crystals with the uranium-thorium-helium dating method. Biren then identified and processed shocked zircon fragments for imaging and chemical analysis with an electron microprobe.

“This research adds a tool for investigators dating terrestrial impact structures,” Biren said. “Our results demonstrate the uranium-thorium-helium dating method’s viability for use in similar cases, where shocked materials were ejected away from the crater and then allowed to cool quickly, especially in cases where the sample size is small.”

Reference:
M. B. Biren, J.-A. Wartho, M. C. VAN Soest, K. V. Hodges, H. Cathey, B. P. Glass, C. Koeberl, J. W. Horton, W. Hale. (U-Th)/He zircon dating of Chesapeake Bay distal impact ejecta from ODP site 1073. Meteoritics & Planetary Science, 2019; 54 (8): 1840 DOI: 10.1111/maps.13316

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

Meteorite strikes made life on Earth possible

August 14, 2019

Representative Image: An example of a Pallasite meteorite (from the Esquel fall) on display in the Vale Inco Limited Gallery of Minerals at the Royal Ontario Museum. Credit: Captmondo/Wikimedia

Meteorites from the far reaches of the solar system delivered large amounts of water, carbon and volatile substances to the Earth. Only then could the Earth host life. Dr. María Isabel Varas-Reus, Dr. Stephan König, Aierken Yierpan and Professor Dr. Ronny Schönberg from Tübingen University’s Isotope Geochemistry Group, and Dr. Jean-Pierre Lorand from the Université de Nantes, provide evidence for this scenario in a new study. Using a method recently developed at the University of Tübingen, the researchers measured selenium isotopes in rocks derived from the Earth’s mantle. Identical isotope signatures in these rocks and in certain types of meteorites revealed the origin of the selenium as well as large amounts of water and other vital substances. The study has been published in the latest Nature Geoscience.

Strictly speaking, there shouldn’t be any selenium in the Earth’s mantle. “It is attracted to iron. That is why, in the early history of our planet, it went down into the iron-rich core,” Dr. María Isabel Varas-Reus explains. There was no more selenium in the Earth’s outer layer. “The previous selenium signatures were completely erased there. The selenium found in the Earth’s mantle today must therefore have been added after the formation of the Earth’s core. Geologically speaking, “at the last moment of the formation of the Earth, after our moon had also formed,” Varas-Reus adds. It’s hard to say exactly when—it could have been between 4.5 and 3.9 billion years ago.

Complex measurements

In various places, the research team took samples of mantle rocks, which have been brought to the surface by plate tectonic processes and had remained unchanged with regard to its selenium isotope composition since the formation of the Earth. The researchers determined the isotope signature of the selenium in these rocks. Isotopes are atoms of the same chemical element with different weights. “It has been possible for some time now to measure selenium isotopes in high concentrations—for example in samples from rivers,” says Varas-Reus. “However, the selenium concentration in high-temperature rocks is very low. Samples must be dissolved out at high temperatures, and selenium is volatile. This makes the measurements difficult.” But recently it became possible to measure selenium isotopes in high-temperature rocks. Dr. Stephan König and his group of researchers developed a complex method as part of his ERC grant, the O2RIGIN project funded by the European Research Council.

It has long been suspected that meteorites added substances to the Earth’s mantle. “But we thought they were meteorites from the inner solar system,” Varas-Reus says. “So we were very surprised that the selenium isotope signature of the Earth’s mantle closely matched a certain type of meteorite from the outer solar system. These are carbonaceous chondrites from the solar system beyond the asteroid belt, from the area of the planets Jupiter, Saturn, Uranus and Neptune. The selenium isotope signatures of various meteorites were collected by the geologist Dr. Jabrane Labidi, a former O2RIGIN collaborator, in a previous study.

The research team was also able to quantify what else—apart from selenium—these meteorites brought with them when they hit the early Earth. “According to our calculations, around 60 percent of the water on Earth today comes from this source. That is the only way oceans could eventually form,” says Varas-Reus. Volatile substances from the meteorites contributed to the formation of the earth’s protective atmosphere. “This created the conditions for life on Earth to develop in its present form.”

Reference:
María Isabel Varas-Reus et al. Selenium isotopes as tracers of a late volatile contribution to Earth from the outer Solar System, Nature Geoscience (2019). DOI: 10.1038/s41561-019-0414-7

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

Giant penguin fossil found in New Zealand

August 14, 2019

Canterbury Museum researcher Vanesa De Pietri (L) said the discovery reinforces the theory that penguins attained great size early in their evolution

The fossilised remains of a huge penguin almost the size of an adult human have been found in New Zealand’s South Island, scientists announced Wednesday.

The giant waddling sea bird stood 1.6 metres (63 inches) high and weighed 80 kilograms, about four times heavier and 40cm taller than the modern Emperor penguin, researchers said.

Named “crossvallia waiparensis”, it hunted off New Zealand’s coast in the Paleocene era, 66-56 million years ago.

An amateur fossil hunter found leg bones belonging to the bird last year and it was confirmed as a new species in research published this week in Alcheringa: An Australasian Journal of Palaeontology.

Canterbury Museum researcher Vanesa De Pietri said it was the second giant penguin from the Paleocene era found in the area.

“It further reinforces our theory that penguins attained great size early in their evolution,” she said.

Scientists have previously speculated that the mega-penguins eventually died out due to the emergence of other large marine predators such as seals and toothed whales.

New Zealand is well known for its extinct giant birds, including the flightless moa, which was up to 3.6-metres tall, and Haast’s eagle, which had a wingspan of three metres.

Just last week, Canterbury Museum announced the discovery of a prodigious parrot that was one metre tall and lived about 19 million years ago.

Reference:
Gerald Mayr et al. Leg bones of a new penguin species from the Waipara Greensand add to the diversity of very large-sized Sphenisciformes in the Paleocene of New Zealand, Alcheringa: An Australasian Journal of Palaeontology (2019). DOI: 10.1080/03115518.2019.1641619

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

Aquamarine : The World’s Largest Aquamarine Gem – Dom Pedro Aquamarine

August 13, 2019

The Dom Pedro aquamarine obelisk by gem sculptor Bernd Munsteiner

What is Aquamarine?

Aquamarine is a blue or cyan variety of beryl. It happens in most locations where normal beryl is produced. Sri Lanka’s deposits of gem-gravel placer contain aquamarine. Green-yellow beryl is sometimes referred to as chrysolite aquamarine, as happening in Brazil. Aquamarine’s deep blue version is called maxixe. Maxixe is frequently discovered in the Madagascar nation. When exposed to sunlight or undergoing heat treatment, its color fades to white, although the color returns with irradiation.

Aquamarine’s pale blue colour is ascribed to Fe2 +. Fe3 + electrons generate golden-yellow colour, and when both Fe2 + and Fe3 + are present, the colour is as dark as maxixe. Light or heat decoloration of the maxix may therefore be due to the transfer of charges between Fe3 + and Fe2 +. By irradiating it with high-energy particles (gamma rays, neutrons or even X-rays), dark-blue maxix color can be produced in green, pink or yellow beryl.

Aquamarines can be discovered at the Mt. Antero peak in the Sawatch Range in central Colorado in the United States. Aquamarine was found in Wyoming, close Powder River Pass, in the Big Horn Mountains. Another U.S. place is the Sawtooth Range close Stanley, Idaho, although the minerals are within a wilderness area that prohibits collection. In Brazil, in the countries of Minas Gerais, Espírito Santo, and Bahia, and in Rio Grande do Norte, there are mines. Aquamarine is also produced by Colombia, Zambia, Madagascar, Malawi, Tanzania and Kenya mines.

The biggest Cut aquamarine gem in the world

The aquamarine Dom Pedro is the biggest cut aquamarine gem in the world. It was trimmed from a crystal with an original weight of about 100 pounds (45 kg) and a span of over 3 feet (0.91 m). The rock was mined around 1980 in Pedra Azul, Brazil’s Minas Gerais state, named after the Brazilian emperors Pedro I and Pedro II.

Bernd Munsteiner cuted the blue-green gemstone into an obelisk shape weighing 10,363 carats. The completed size is 14 inches (36 cm) high by 4 inches (10 cm) broad. Jane Mitchell and Jeffery Bland donated the gem to the Smithsonian Institution. It is located in the Janet Annenberg Hooker Hall of Geology of the National Museum of Natural History.

Dom Pedro Aquamarine

The Dom Pedro Aquamarine, the biggest single piece of cut-gem aquamarine in the globe, will be permanently displayed at the National Museum of Natural History starting Dec. 6. In the Janet Annenberg Hooker Hall of Geology, Gems and Minerals such as the Hope Diamond and the Marie Antoinette necklace, it connects an illustrious set of renowned gemstones already on display. The piece was given by Jane M. Mitchell and Jeffery S. Bland. It is an extremely rare gem due to the quality of the initial crystal and its size, magnificent blue-green colour and unique shape.

“There’s so much noteworthy about the Dom Pedro, but what excites me most is that we can maintain the tale that comes with it,” said Kirk Johnson, National Museum of Natural History’s Sant Director. “The Dom Pedro is enhanced by all the people and places in the National Gem Collection that were component of his intriguing trip from the Earth’s crust to his home here. We are thankful for their fantastic donation to Jane Mitchell and Jeffery Bland.

Mined from a Brazilian pegmatite in the early 1980s, for the first two presidents of Brazil, Dom Pedro Primeiro and his brother, Dom Pedro Segundo, the splendid aquamarine was appointed. The portion of the beryl crystal from which the obelisk-shaped gem was fashioned was 23.25 inches long and weighed almost 60 pounds before cutting. The obelisk, built by Bernd Munsteiner, a world-renowned gem artist, lies 14 inches high, measures 4 inches across the foundation and averages 10,363 carats or 4.6 pounds. These amazing sizes make the Dom Pedro recognized as the biggest aquamarine cut-and-polished gem. A model of tapering “adverse splits” facing the sea-blue obelisk’s opposite sides helps to represent the light within the gem, giving the piece startling brightness and brightness. This notable sculpture appears to be illuminated from the inside with the correct lighting.

Munsteiner is considered one of the 20th century’s greatest gem artists, the “Father of the Fantasy Cut.” In order to produce gem carvings, he mixes traditional techniques with vibrant contemporary types. Born to a family of jewel carvers, Munsteiner’s job is the expression of an art practice that has gone from generation to generation.

At the era of 14, he became a family business apprentice and subsequently became a teacher at the School of Design in Phorzheim, Germany, where he graduated as a manufacturer of precious stones and jewelry. It was at college that Munsteiner was invited to bring the traditional cameo into a fresh shape for the first time, and he has since stretched borders and questioned traditional techniques. His faceting method recognized as “Fantasy Cuts” has influenced a modernization of the development of gem art, and the Dom Pedro Aquamarine exemplifies his creative style. Munsteiner spent four months researching the crystal carefully and another six months cutting, polishing and faceting to produce this unparalleled art job.

Apart from 350,000 mineral specimens, the Dom Pedro Aquamarine joins the Smithsonian’s famous gem and mineral collection of over 10,000 gems. The Smithsonian’s collection of gems and minerals is one of its biggest.

Researchers discover oldest fossil forest in Asia

August 13, 2019

Reconstructions of lycopsid trees (Guangdedendron micrum). Left: juvenile plant. Right: adult plant. Credit: Zhenzhen Deng

The Devonian period, which was 419 million to 359 million years ago, is best known for Tiktaalik, the lobe-finned fish that is often portrayed pulling itself onto land. However, the “age of the fishes,” as the period is called, also saw evolutionary progress in plants. Researchers reporting August 8 in the journal Current Biology describe the largest example of a Devonian forest, made up of 250,000 square meters of fossilized lycopsid trees, which was recently discovered near Xinhang in China’s Anhui province. The fossil forest, which is larger than Grand Central Station, is the earliest example of a forest in Asia.

Lycopsids found in the Xinhang forest resembled palm trees, with branchless trunks and leafy crowns, and grew in a coastal environment prone to flooding. These lycopsid trees were normally less than 3.2 meters tall, but the tallest was estimated at 7.7 meters, taller than the average giraffe. Giant lycopsids would later define the Carboniferous period, which followed the Devonian, and become much of the coal that is mined today. The Xinhang forest depicts the early root systems that made their height possible. Two other Devonian fossil forests have been found: one in the United States, and one in Norway.

“The large density as well as the small size of the trees could make Xinhang forest very similar to a sugarcane field, although the plants in Xinhang forest are distributed in patches,” says Deming Wang, a professor in the School of Earth and Space Sciences at Peking University, co-first author on the paper along with Min Qin of Linyi University. “It might also be that the Xinhang lycopsid forest was much like the mangroves along the coast, since they occur in a similar environment and play comparable ecologic roles.”

The fossilized trees are visible in the walls of the Jianchuan and Yongchuan clay quarries, below and above a four-meter thick sandstone bed. Some fossils included pinecone-like structures with megaspores, and the diameters of fossilized trunks were used to estimate the trees’ heights. The authors remarked that it was difficult to mark and count all the trees without missing anything.

“Jianchuan quarry has been mined for several years and there were always some excavators working at the section. The excavations in quarries benefit our finding and research. When the excavators stop or left, we come close to the highwalls and look for exposed erect lycopsid trunks,” says Wang, who, with Qin, found the first collection of fossil trunks in the mine in 2016. “The continuous finding of new in-situ tree fossils is fantastic. As an old saying goes: the best one is always the next one.”

This work was supported by The National Natural Science Foundation of China.

Reference:
Deming Wang, Min Qin, Le Liu, Lu Liu, Yi Zhou, Yingying Zhang, Pu Huang, Jinzhuang Xue, Shihui Zhang, Meicen Meng. The Most Extensive Devonian Fossil Forest with Small Lycopsid Trees Bearing the Earliest Stigmarian Roots. Current Biology, 2019; DOI: 10.1016/j.cub.2019.06.053

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

A new timeline of Earth’s cataclysmic past

August 13, 2019

Depictions of large asteroids striking Earth, which, during parts of its early history, would have had a much thicker atmosphere than it does today. Credits: NASA with modifications by Stephen Mojzsis

Welcome to the early solar system. Just after the planets formed more than 4.5 billion years ago, our cosmic neighborhood was a chaotic place. Waves of comets, asteroids and even proto-planets streamed toward the inner solar system, with some crashing into Earth on their way.

Now, a team led by University of Colorado Boulder geologist Stephen Mojzsis has laid out a new timeline for this violent period in our planet’s history.

In a study published today, the researchers homed in on a phenomenon called “giant planet migration.” That’s the name for a stage in the evolution of the solar system in which the largest planets, for reasons that are still unclear, began to move away from the sun.

Drawing on records from asteroids and other sources, the group estimated that this solar system-altering event occurred 4.48 billion years ago — much earlier than some scientists had previously proposed.

The findings, Mojzsis said, could provide scientists with valuable clues around when life might have first emerged on Earth.

“We know that giant planet migration must have taken place in order to explain the current orbital structure of the outer solar system,” said Mojzsis, a professor in the Department of Geological Sciences. “But until this study, nobody knew when it happened.”

It’s a debate that, at least in part, comes down to moon rocks collected by Apollo astronauts — many of which seemed to be only 3.9 billion years old, hundreds of millions of years younger than the moon itself.

To explain those ages, some researchers suggested that our moon, and Earth, were slammed by a surge of comets and asteroids around that time. But not everyone agreed with the theory, Mojzsis said.

“It turns out that the part of the moon we landed on is very unusual,” he said. “It is strongly affected by one big impact, the Imbrium Basin, that is about 3.9 billion years old and affects nearly everything we sampled.”

To get around that bias, the researchers decided to compile the ages from an exhaustive database of meteorites that had crash landed on Earth.

“The surfaces of the inner planets have been extensively reworked both by impacts and indigenous events until about 4 billion years ago,” said study coauthor Ramon Brasser of the Earth-Life Science Institute in Tokyo. “The same is not true for the asteroids. Their record goes back much further.”

But those records, the team discovered, only went back to about 4.5 billion years ago.

For the researchers, that presented only one possibility: The solar system must have experienced a major bombardment just before that cut-off date. Very large impacts, Mojzsis said, can melt rocks and variably reset their radioactive ages, a bit like shaking an etch-a-sketch.

Mojzsis explained that this carnage was likely kicked off by the solar system’s giant planets, which researchers believe formed much closer together than they are today. Using computer simulations, however, his group demonstrated that those bodies started to creep toward their present locations about 4.48 billion years ago.

In the process, they scattered the debris in their wake, sending some of it hurtling toward Earth and its then-young moon.

The findings, Mojzsis added, open up a new window for when life may have evolved on Earth. Based on the team’s results, our planet may have been calm enough to support living organisms as early as 4.4 billion years ago.

Other co-authors on the study include Nigel Kelly, formerly of CU Boulder, Oleg Abramov at the Planetary Science Institute and Stephanie Werner at the University of Oslo.

Reference:
Stephen J. Mojzsis, Ramon Brasser, Nigel M. Kelly, Oleg Abramov, Stephanie C. Werner. Onset of Giant Planet Migration before 4480 Million Years Ago. The Astrophysical Journal, 2019; 881 (1): 44 DOI: 10.3847/1538-4357/ab2c03

Note: The above post is reprinted from materials provided by University of Colorado at Boulder. Original written by Daniel Strain.

Rock scratches hint at future quakes

August 13, 2019

Jesse leaning against the fresh fault scarp of the Kekerengu fault, next to some of the curved slickenlines. Credit: Professor Tim Little

Curved scratches in rock faces may give clues to where big quakes could strike next, a study led by Victoria University of Wellington Master’s student Jesse Kearse has shown.

These scratches—or ‘slickenlines’—have been observed on fault lines for decades. Through his Master’s research—published last month in the journal Geology—Jesse was able to link the direction of the slickenlines with the direction a fault line ruptures during an earthquake, providing a record of how past earthquakes have moved on New Zealand’s fault lines and hints as to where future earthquake damage could occur.

Jesse’s research began when he was analysing the Kekerengu fault line as part of the Kaikōura Earthquake Surface Rupture Response Team immediately following the Kaikōura earthquake.

“We were mapping the ground ruptures that occurred around the Kekerengu fault as a result of the Kaikōura earthquake, and we found these intriguing curved marks,” Jesse says. “We wanted to uncover the process behind their formation, because we knew this was a field of research that wasn’t well understood.”

Alongside his supervisors Professor Tim Little of Victoria University of Wellington and Russ van Dissen from GNS Science, Jesse spent many weeks in the field, walking the ground ruptures from end to end—a total distance of 30 kilometres—documenting the ground deformation, and recording the slickenlines.

“After completing these observations, we took our data back to the lab for analysis,” Jesse says. “We knew that the rupturing of the Kekerengu fault had caused the ground to shift sideways by up to 12 m during the Kaikoura earthquake. Our analysis of the slickenlines not only confirmed this movement, but also provided further detailed information about how the fault moved—not in a straight line, but along a complicated, curved route.”

With help from seismologist Yoshi Kaneko from GNS, who uses computer programs to model the dynamics of earthquake ruptures, they were able to confirm that curved slickenlines like the ones they observed on the Kekerengu fault are related to the direction an earthquake moves along the fault.

It has long been known that the direction a fault ruptures can strongly affects the distribution of ground shaking and damage resulting from an earthquake, Jesse says.

“In the Kaikōura earthquake, for example, Wellington experienced much stronger shaking than Christchurch, even though the epicentre of the quake was much closer to Christchurch,” Jesse says. “This is because the Kekerengu fault ruptured towards the north, and so the earthquake energy was focused in that direction.”

Now Jesse and his colleagues can analyse the slickenlines in other faults to see how they have ruptured in the past, including prehistoric earthquakes that took place thousands of years ago.

“We might be able to better predict how they will rupture in the future and where the ground shaking and damage from earthquakes on these faults will occur,” Jesse says. “This will help plan for future quakes, including designing more resilient buildings and architecture in areas that could suffer more quake damage.”

Jesse hopes to see this research tested further across the world to confirm their findings and provide a new way for scientists to discover information about earthquakes.

“This research is very new, so while it’s very exciting it still needs to be tested and verified by the global earth science community,” Jesse says. “Hopefully this analysis will prove that these findings are of real benefit to the lives of people living in earthquake prone regions around the world.”

Reference:
Jesse Kearse et al. Curved slickenlines preserve direction of rupture propagation, Geology (2019). DOI: 10.1130/G46563.1

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

Hidden mysteries lie in wait inside Kenya’s fossil treasury

August 13, 2019

The 23-million-year-old bones of the newly-discovered giant, Simbakubwa kutokaafrika, had been left for nearly 40 years in a drawer

The only hint that something extraordinary lay inside the plain wooden drawer in an unassuming office behind Nairobi National Museum was a handwritten note stuck to the front: “Pull Carefully”.

Inside, a monstrous jawbone with colossal fangs grinned from a bed of tattered foam—the only known remains of a prehistoric mega-carnivore, larger than a polar bear, that researchers only this year declared a new species.

“This is one-of-a-kind,” said Kenyan paleontologist Job Kibii, holding up the 23-million-year-old bones of the newly-discovered giant, Simbakubwa kutokaafrika, whose unveiling made headlines around the world.

But the remarkable fossils were not unearthed this year, or even this decade. They weren’t even found this century.

For nearly 40 years, the specimens—proof of the existence of Africa’s largest-ever predator, a 1,500 kilogram (3,300-pound) meat eater that dwarfed later hunters like lions—lived in a nondescript drawer in downtown Nairobi.

Museum staff knew the bones were something special—they just didn’t know what exactly. A source of intrigue, dusted off on occasion for guests, Simbakubwa lay in wait, largely forgotten.

How did these fossils, first excavated on a dig in western Kenya in the early 1980s, go unrecognised for so long?

Kibii—who presides over the National Museums of Kenya’s paleontology department, a collection unrivalled in East Africa and one of the world’s great fossil treasuries—has a pretty good idea.

“We have tonnes and tonnes of specimens… that haven’t been analysed,” he told AFP.

“Definitely there are things waiting to be discovered.”

Out of space

The main wing has changed little since legendary paleoanthropologist Louis Leakey first started stockpiling his finds there in the early 1960s.

A card-based filing system is still used to find a specific fossil among the trove, the entries written by hand.

But the collection has grown exponentially, faster than Kibii and his team can keep up.

“We’ve run out of space,” said Kibii, pausing between dusty archival shelves crammed floor to ceiling with finds, dating back more than half a century.

“In this section alone, we have more than a million specimens.”

Gigantic skulls of ancient crocodiles compete for space with a bygone species of horned giraffe.

Nearby, the behemoth tusks of an early African elephant take up valuable real estate.

Even the windowsills are littered with the petrified remains of all manner of weird and wonderful creatures.

Between 7,000 and 10,000 new fossils arrive at the lab every year, Kibii says, overwhelming his 15 staff who must painstakingly clean and log each specimen.

By law, fossils uncovered in Kenya must go to the museum for “accessioning”—the process of labelling, recording and storing for future generations.

The backlog is enormous.

Chipping away

In a dark room, a lone staffer in a protective mask blasts away rock from fossil using an air-powered brush, as Kenyan pop tunes crackle through an old radio.

Outside the door, metal chests sent from dig sites filled to the brim await his magic touch—literally years of work stretching before him.

If a specific expert is not on hand to identify a specimen, things can get wrongly categorised or waylaid.

In some cases, they’re sent to the dreaded “waiting area”, where faded cardboard boxes, sagging with unknown and abandoned fossils, gather dust.

“We have fossils from the 1980s that have not been accessioned,” said collections manager Francis Muchemi, chipping away at a giant elephant molar.

‘Cradle of humanity’

Simbakubwa met a similar fate.

Thought to be a type of hyena, it was filed away in a backroom and unstudied for decades, until stumbled upon by American researchers.

Specific finds unearthed at one of Kenya’s many digs by researchers writing academic papers are given priority and fast-tracked for assessment by the museum.

Even today though, the museum lacks specialists and resources.

Kibii is one of just seven paleontologists in Kenya. He trained in South Africa because there was no course available at home.

“It’s important because Kenya is the cradle of human evolution,” said Muchemi, who learned his skills on the job.

“We have very few Kenyans doing this job. Ninety-nine percent of the people who work here are foreign.”

Kibii said paleontology was considered a lower priority than conserving Africa’s endangered wildlife.

“This one has been in the ground for millions of years. What are you saving it from?” he said, of the prevailing attitude to the science.

He hopes to acquire collapsable shelves to create space in the collection.

Even better, a micro-CT scanner—a powerful tool driving breakthroughs in the world of paleontology—would allow a fresh look at the museum’s most-forgotten corners.

“I always wonder what lies in there on some of these shelves,” Kibii said.

“Simbakubwa is telling a new story. What if, among these thousands, we have 10, 20, new stories that are lying, waiting to be told? That’s always the mystery.”

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

Ancient drop of water rewrites Earth’s history

August 8, 2019

A diagrammatic representation of the Earth in the Archaean showing subducted ocean floor carrying its chemical signature into the deep mantle. The signature which includes water and chlorine is preserved in melt inclusions contained within olivine and carried back up to surface within komatiite lava flows.

The remains of a microscopic drop of ancient seawater has assisted in rewriting the history of Earth’s evolution when it was used to re-establish the time that plate tectonics started on the planet.

Plate tectonics is Earth’s vital — and unique — continuous recycling process that directly or indirectly controls almost every function of the planet, including atmospheric conditions, mountain building (forming of continents), natural hazards such as volcanoes and earthquakes, formation of mineral deposits and the maintenance of our oceans. It is the process where the large continental plates of the planet continuously move, and the top layers of the Earth (crust) are recycled into the mantle and replaced by new layers through processes such as volcanic activity.

Where it was previously thought that plate tectonics started about 2.7 billion years ago, a team of international scientists used the microscopic leftovers of a drop of water that was transported into the Earth’s deep mantle — through plate tectonics — to show that this process started 600 million years before that. An article on their research that proves plate tectonics started on Earth 3.3 billion years ago was published in the high impact academic journal, Nature, on 16 July.

“Plate tectonics constantly recycles the planet’s matter, and without it the planet would look like Mars,” says Professor Allan Wilson from the Wits School of Geosciences, who was part of the research team.

“Our research showing that plate tectonics started 3.3 billion years ago now coincides with the period that life started on Earth. It tells us where the planet came from and how it evolved.”

Earth is the only planet in our solar system that is shaped by plate tectonics and without it the planet would be uninhabitable.

For their research, the team analysed a piece of rock melt, called komatiite — named after the type occurrence in the Komati river near Barberton in Mpumalanga — that are the leftovers from the hottest magma ever produced in the first quarter of Earth’s existence (the Archaean). While most of the komatiites were obscured by later alteration and exposure to the atmosphere, small droplets of the molten rock were preserved in a mineral called olivine. This allowed the team to study a perfectly preserved piece of ancient lava.

“We examined a piece of melt that was 10 microns (0.01mm) in diameter, and analysed its chemical indicators such as H2O content, chlorine and deuterium/hydrogen ratio, and found that Earth’s recycling process started about 600 million years earlier than originally thought,” says Wilson. “We found that seawater was transported deep into the mantle and then re-emerged through volcanic plumes from the core-mantle boundary.”

The research allows insight into the first stages of plate tectonics and the start of stable continental crust.

“What is exciting is that this discovery comes at the 50th anniversary of the discovery of komatiites in the Barberton Mountain Land by Wits Professors, the brothers Morris and Richard Viljoen,” says Wilson.

Reference:
Alexander V. Sobolev, Evgeny V. Asafov, Andrey A. Gurenko, Nicholas T. Arndt, Valentina G. Batanova, Maxim V. Portnyagin, Dieter Garbe-Schönberg, Allan H. Wilson, Gary R. Byerly. Deep hydrous mantle reservoir provides evidence for crustal recycling before 3.3 billion years ago. Nature, 2019; 571 (7766): 555 DOI: 10.1038/s41586-019-1399-5

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

Synchronization of ice cores using volcanic ash layers

August 8, 2019

An electron scanning microscope picture of an ash sample from a 55,500 years old ash layer in the NGRIP ice core. The ash shards are the larger pieces that look like broken glass. The colours are not true. The white bar at the bottom left represents 1/10 mm. Credit: University of Copenhagen

Thin, brownish layers of a thickness of about a millimeter or two are sometimes observed in the whitish/transparent ice cores. These brown layers consist of material originating from volcanic eruptions.

During a volcanic eruption, gases, lava, rocks, and tiny ash particles are being ejected into the atmosphere. The smallest particles are carried by the wind and transported with the air masses, until the particles drop out and cover the land or ice surface with a thin blanket of volcanic material. Ash that landed on the ice sheet of Greenland thousands of years ago are buried under huge amounts of ice today and can only be retrieved by drilling long ice cores.

Many of the ash particles in the ice cores are too small to be visible to the naked eye. Most often the particles are only one tenth or one hundredth of a millimeter. Only when a huge amount of ash particles is present in a layer, the layer will be visible in the ice core as a thin brown band, but most of the volcanic layers in ice cores are invisible because of the small amount of ash shards. Searching for these ash layers in a three kilometer long ice core may seem like an impossible task. Nevertheless, this is what researchers at the Centre for Ice and Climate do.

The volcanic ash layers can be used as important reference horizons that can link different ice cores and other archives of past climate. The volcanic ash also contains a chemical fingerprint which makes it possible to trace which volcano the ash originates from, and sometimes also which eruption of a particular volcano was the source. It is this property that encourages the researchers to look for the tiny ash particles that are hidden in the long ice cores.

Identification and analysis of volcanic ash

It may seem like an impossible task to find the invisible ash layers in a three kilometer long ice core, consisting of about 20 tonnes of ice. Luckily, some help is at hand. Following a volcanic eruption, the precipitation is often slightly acidic due to the presence of sulphuric acid that comes from conversion of the volcanic sulphuric gases in the atmosphere. The relatively high acid concentrations lead to high electrical conductivity of the ice. It is fast and relatively easy to measure the electrical conductivity of the ice, and the acid peaks in the measured profile can be used as guides for where the tiny ash particles are hiding. Ice samples will usually be cut around where acid peaks are found, but unfortunately there is no guarantee that ash is present, so the samples have to be analyzed very carefully.

The ice samples are melted and centrifuged in order to pour off the water and keep the small amount of impurity particles from the ice. Most of the material is wind-blown dust or fine-grained sand, often coming all the way from deserts in Asia. If ash shards are present, these can be identified visually in a normal light microscope or in an electron scanning microscope.

An ash shard can often be identified by its glassy and shiny look, its particular shape and its transparency. The particles are normally either colorless or light pinkish or brownish, depending on the chemical composition.

After identification of an ash layer, the chemical analysis can start using an electron microprobe. This instrument works by shooting an electron beam at the ash particle investigated. The chemical composition of the shards can be inferred from the wavelengths of the X-rays that are emitted from the sample. Chemical results of good quality require that the samples are prepared well before analysis. This process is very laborious. All the shards to be analyzed need to have a flat and smooth surface and should be at the same level relative to the electron gun in the microprobe. One way to do this is to mount the shards in a resin (epoxy) on a glass slide and then polish the sample with fine-grained diamond dust. The surface of the sample is slowly being removed and polished by the hard diamond dust. Care is taken not to polish away all the precious shards. During the polishing, a microscope is used to check if the surface of the shard is flat and smooth.

When the chemical composition of the shards has been determined, the results are compared with results from analysis of similar shards in other ice or sediment cores or with the composition of ashes found in situ at the volcano responsible for the eruption.

Reference:
Brad S. Singer et al. Synchronizing volcanic, sedimentary, and ice core records of Earth’s last magnetic polarity reversal, Science Advances (2019). DOI: 10.1126/sciadv.aaw4621

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

Sex appeal helped dinosaurs take flight

August 8, 2019

A flightless dinosaur called Similicaudipteryx uses its feathers in a mating display. U of A researchers looked at how such displays may have helped dinosaurs evolve feathers that eventually allowed them to fly. Credit: Sydney Mohr

Attracting mates with showy displays may have helped dinosaurs develop feathers that let them take flight, according to new research by University of Alberta paleontologists.

“The first complex wing feathers show up in tiny raptor dinosaurs that could parachute and glide flying-squirrel-style through the prehistoric treetops,” said Scott Persons, who led the study while he was a post-doctoral researcher at the U of A.

“In this study, we explored how dinosaurs went from staying warm with simple hairy feathers to gliding on complicated wing feathers.”

The study makes the case that larger, stiffer, flatter feathers gradually evolved as showy fans on the arms and tails of dinosaurs to be waved and waggled in courtship displays, leading eventually to the evolution of birds—an interpretation supported by a growing fossil record of early feathers.

“Sexual display remains an important function of complex feathers in some birds to this day,” said Persons, who is now at the College of Charleston. “Think of the feather fans of turkeys and peacocks or the head crest of a cockatoo.”

A missing link

Persons said the feathers on a bird’s wing each have a central hollow shaft called a rachis whereas fossil feathers on many dinosaurs were covered only in simple hair-like feathers that nothing to do with flight. They served as insulation to keep dinosaurs warm.

“Going from simple hairy feathers to sophisticated flight feathers is a big jump. Evolution doesn’t normally work in big jumps. It’s gradual,” explained Persons. “Recognizing the intermediate function of sexual display explains a gradual way for simple feathers to have grown in complexity.”

Though the study offers clues about the evolutionary steps leading from dinosaurs to birds, there are still rich paleontological mysteries to explore concerning fossil feathers, Persons noted.

“We are still missing clear examples of sexually dimorphic feathers in dinosaurs. Today, it’s easy to tell the sexes of many birds apart based on their feathers,” he said. “Male birds tend to have larger, gaudier and brighter feathers because they are the ones doing the displaying.

“This was very likely true of feathered dinosaurs, but we haven’t found a definitive example … yet.”

The study, “Feather Evolution Exemplifies Sexually Selected Bridges Across the Adaptive Landscape,” was published in Evolution.

Reference:
W. Scott Persons et al. Feather evolution exemplifies sexually selected bridges across the adaptive landscape, Evolution (2019). DOI: 10.1111/evo.13795

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

New species of early dinosaur described from South Africa

August 8, 2019

Ngwevu intloko skull. Credit: Kimberley Chapelle

A new dinosaur species has been discovered after laying misidentified in a museum collection for 30 years.

Prof Paul Barrett, a dinosaur researcher at the Natural History Museum, is part of a team that reassessed the specimen, which is held at the University of Witwatersrand, Johannesburg. Along with his colleagues in South Africa, and led by Paul’s Ph.D. student Kimberley Chapelle, they recognised it not only as a new species of sauropodomorph, but an entirely new genus. The specimen has now been named Ngwevu intloko which means “grey skull” in the Xhosa language, chosen to honour South Africa’s heritage.

Prof Barrett explains, “This is a new dinosaur that has been hiding in plain sight. “The specimen has been in the collections in Johannesburg for about 30 years, and lots of other scientists have already looked at it. But they all thought that it was simply an odd example of Massospondylus.”

Massospondylus was one of the first dinosaurs to reign at the start of the Jurassic period. Regularly found throughout southern Africa, these animals belonged to a group called the sauropodomorphs and eventually gave rise to the sauropods, a group containing the Natural History Museum’s iconic dinosaur cast Dippy. Researchers are now starting to look closer at many of the supposed Massospondylus specimens, believing there to be much more variation than first thought.

Kimberley Chapelle explains why the team were able to confirm that this specimen was a new species, “In order to be certain that a fossil belongs to a new species, it is crucial to rule out the possibility that it is a younger or older version of an already existing species. This is a difficult task to accomplish with fossils because it is rare to have a complete age series of fossils from a single species. Luckily, the most common South African dinosaur Massospondylus has specimens ranging from embryo to adult! Based on this, we were able to rule out age as a possible explanation for the differences we observed in the specimen now named Ngwevu intloko.”

The new dinosaur has been described from a single fairly complete specimen with a remarkably well-preserved skull. The new dinosaur was bipedal with a fairly chunky body, a long slender neck and a small, boxy head. It would have measured three metres from the tip of its snout to the end of its tail and was likely an omnivore, feeding on both plants and small animals.

The findings will help scientists better understand the transition between the Triassic and Jurassic period, around 200 million years ago. Known as a time of mass extinction it now seems that more complex ecosystems were flourishing in the earliest Jurassic than previously thought.

“This new species is interesting,” says Prof Barrett, ‘because we thought previously that there was really only one type of sauropodomorph living in South Africa at this time. We now know there were actually six or seven of these dinosaurs in this area, as well as variety of other dinosaurs from less common groups. It means that their ecology was much more complex than we used to think. Some of these other sauropodomorphs were like Massospondylus, but a few were close to the origins of true sauropods, if not true sauropods themselves.”

This work shows the value of revisiting specimens in museum collections, as many news species are probably sitting unnoticed in cabinets around the world.

The new paper “Ngwevu intloko: a new early sauropodomorph dinosaur from the Lower Jurassic Elliot Formation of South Africa and comments on cranial ontogeny in Massospondylus carinatus” is published in the journal PeerJ.

Reference:
Kimberley E.J. Chapelle et al. Ngwevu intloko: a new early sauropodomorph dinosaur from the Lower Jurassic Elliot Formation of South Africa and comments on cranial ontogeny in Massospondylus carinatus, PeerJ (2019). DOI: 10.7717/peerj.7240

Note: The above post is reprinted from materials provided by Natural History Museum.

Newly discovered Labrador fossils give clues about ancient climate

August 8, 2019

This fossilized tree leaf, is the first of their kind to have been found in the area. Alexandre Demers-Potvin, used the samples he collected to establish that Eastern Canada would have had a warm temperate and fully humid climate during the middle of Cretaceous period. Credit: Alexandre Demers-Potvin

The discovery of fossilized plants in Labrador, Canada, by a team of McGill directed paleontologists provides the first quantitative estimate of the area’s climate during the Cretaceous period, a time when the earth was dominated by dinosaurs.

The specimens were found in the Redmond no.1 mine, in a remote area of Labrador near Schefferville, in August 2018. Together with specimens collected in previous expeditions, they are now at the core of a recent study published in Palaeontology.

Some of the specimens, are the first of their kind to have been found in the area. Alexandre Demers-Potvin, a graduate student under the supervision of Professor Hans Larsson, Canada Research Chair in Vertebrate Palaeontology at McGill University, used the samples he collected to establish that Eastern Canada would have had a warm temperate and fully humid climate during the middle of Cretaceous period.

Fossilized leaves and insects, known to be very similar to communities that today live further south, had been found at the Redmond No. 1 mine in the late 1950s had led paleontologists to hypothesize that the cretaceous climate of Quebec and Labrador was far warmer than it is today.

With the new samples they found, Demers-Potvin and his colleagues were able to confirm this using the Climate Leaf Analysis Multivariate Program. This tool is used to predict a variety of climate statistics for a given fossil flora, such as temperature and precipitation variables, based on the shape and size of its tree leaves. Their findings put the area’s mean annual temperature around 15°C. Summers were hot — with temperatures of over 20 degrees Celsius — and year-round precipitations relatively high.

Alexandre Demers-Potvin, who is also the study’s first author, said the new work provides insight into how the climate of Eastern Canada evolved over time, useful information to study today’s changing climate.

“The fossils from the Redmond mine show that an area that is now covered by boreal forest and tundra used to be covered in warm temperate forests in the middle of the Cretaceous, one of our planet’s ‘hothouse’ episodes, Demers-Potvin said. These are new pieces of evidence that can help improve projections of the global average temperature against global CO2 levels throughout the Earth’s history.”

Alexandre Demers-Potvin and his collaborators are now undertaking a description of the new fossilized insects discovered at the Redmond site. Demers-Potvin will return to Schefferville in the hopes of finding more insect specimens and fossilized vertebrates that could be hiding in the rubble of the abandoned mine.

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

Predicting the strength of earthquakes

August 8, 2019

Marine Denolle (right) and her team, including Jiuxun Yin (left) and Brad Lipovsky, created numerical models to predict an earthquake’s final magnitude 10 to 15 seconds faster than today’s best algorithms. Credit: Stephanie Mitchell/Harvard Staff Photographer

Scientists will be able to predict earthquake magnitudes earlier than ever before thanks to new research by Marine Denolle, assistant professor in the Department of Earth and Planetary Sciences (EPS).

“For large-strike slip earthquakes like those that occur on the San Andreas Fault, which are likely to rupture for about 50 seconds, we would be able to predict the final magnitudes 2 to 5 seconds after getting the first seismic wave,” said Denolle, senior author of the study that appeared recently in Geophysical Research Letters.

Denolle shares authorship with Philippe Danré, the first author and former EPS visiting master’s student; Jiuxun Yin, a Ph.D. candidate in the Graduate School of Arts and Sciences; and Brad Lipovsky, an EPS researcher. The team also proved that the activity of earthquakes is actually organized, not chaotic as scientists had previously believed.

“Our research, which is technically rather simple, provides answers relevant not only to earthquake dynamics, but to prediction of earthquake behavior before the earthquake ends,” said Denolle. While there is still no way to predict quakes before they begin, current detection systems consist of a series of sensors that transmit signals to determine the location and magnitude once rapid shaking occurs.

Denolle and her team used data products and created numerical models to predict an earthquake’s final magnitude 10 to 15 seconds faster than today’s best algorithms—seconds that could provide enough time for people to exit a building or for officials to stop traffic before shaking starts.

The team began by examining patterns of seismic signals—transient waveforms that radiate from the first rupture in a fault, a thin seam of crushed rock separating two blocks of the earth’s crust. An earthquake occurs when the blocks break free. Scientists read these waves using an underground instrument called a seismometer that translates motions into a graph called a seismogram. “Seismograms give us information about what happened on the fault at the place where the earthquake occurred,” said Denolle.

Denolle and her team combined previous seismograms, which recorded changes in the waves over time as they traveled between the seismometer and the fault. This data product, known as “source time function,” provides a more accurate read on the waves from the source over long distances.

Denolle and her team examined a catalog of source time functions from earthquakes around the globe between 1990 and 2017. They discovered that large earthquakes are actually composed of a series of subevents, smaller events whose size is nearly proportional to the size of the main one. The team concluded that they could predict the final size of an earthquake based on the size of the first few subevents.

“The self-organization of earthquake ruptures is well-explained by heterogeneity on the fault, and our current knowledge of earthquake physics can explain our observations,” said Denolle.

The researchers hope their work will continue to evolve and can one day help improve the algorithms for early warnings of earthquake. To do this, they will work on extracting more accurate high-frequency signals from earthquakes to understand more about their dynamics.

“Eventually, we would hope that the study can provide some guidelines for proper modeling of large earthquakes, and serve as a tool for earthquake early warning, especially for regions expecting large earthquakes, like the Pacific Coast and Japan,” said Denolle.

Reference:
Philippe Danré et al. Earthquakes Within Earthquakes: Patterns in Rupture Complexity, Geophysical Research Letters (2019). DOI: 10.1029/2019GL083093

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

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