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Where Do Rubies Come From?

Where Do Rubies Come From

A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires. Ruby is considered one of the four precious stones, together with sapphire, emerald and diamond.

Prices of rubies are primarily determined by color. The brightest and most valuable “red” called blood-red or “pigeon blood”, commands a large premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. Cut and carat (weight) are also an important factor in determining the price. Ruby is the traditional birthstone for July and is usually more pink than garnet, although some rhodolite garnets have a similar pinkish hue to most rubies. The world’s most expensive ruby is the Sunrise Ruby.

Natural occurrence

The Mogok Valley in Upper Myanmar (Burma) was for centuries the world’s main source for rubies. That region has produced some of the finest rubies ever mined, but in recent years very few good rubies have been found there. The very best color in Myanmar rubies is sometimes described as “pigeon’s blood.” In central Myanmar, the area of Mong Hsu began producing rubies during the 1990s and rapidly became the world’s main ruby mining area. The most recently found ruby deposit in Myanmar is in Namya (Namyazeik) located in the northern state of Kachin.

Rubies have historically been mined in Thailand, the Pailin and Samlout District of Cambodia, Burma, India, Afghanistan, Australia, Namibia, Colombia, Japan, Scotland, Brazil and in Pakistan. In Sri Lanka, lighter shades of rubies (often “pink sapphires”) are more commonly found. After the Second World War ruby deposits were found in Tanzania, Madagascar, Vietnam, Nepal, Tajikistan, and Pakistan.

A few rubies have been found in the U.S. states of Montana, North Carolina, South Carolina and Wyoming. While searching for aluminous schists in Wyoming, geologist Dan Hausel noted an association of vermiculite with ruby and sapphire and located six previously undocumented deposits.

More recently, large ruby deposits have been found under the receding ice shelf of Greenland.

Republic of Macedonia is the only country in mainland Europe to have naturally occurring rubies. They can mainly be found around the city of Prilep. Macedonian ruby has a unique raspberry color. The ruby is also included on the Macedonian Coat of Arms.

In 2002 rubies were found in the Waseges River area of Kenya. There are reports of a large deposit of rubies found in 2009 in Mozambique, in Nanhumbir in the Cabo Delgado district of Montepuez.

Spinel, another red gemstone, is sometimes found along with rubies in the same gem gravel or marble. Red spinel may be mistaken for ruby by those lacking experience with gems. However, the finest red spinels can have a value approaching that of the average ruby.

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

Fingerprinting rare earth elements from the air

Fingerprinting rare earth-GeologyPage
Credit: University of Cambridge

Vital to many modern technologies yet mined in few places, the ‘rare earth elements’ are in fact not that rare – they are just difficult to find in concentrations that make them economic to mine. Researchers from Cambridge University and the British Antarctic Survey (BAS) are investigating whether the remarkable properties of these materials can be used to track them down from the air.

Next time you use your mobile phone, spare a moment for the tiny yet vital ingredients that make this and many other technologies possible – the rare earth elements (REEs).

Used in computers, fibre optic cables, aircraft components and even the anti-counterfeiting system in euro notes, these materials are crucial for an estimated 
£3 trillion worth of industries, with demand set to increase over the coming decades.

Currently, more than 95% of the global demand for the REEs is met by a single mine in China. The security of the future supply of these 17 critical metals, which include neodymium, europium, terbium, dysprosium and yttrium, is a major concern for European governments, and the identification of potential REE resources outside China is seen as a high priority.

Over the past year, Drs Sally Gibson, Teal Riley and David Neave have been working together through a University of Cambridge–BAS Joint Innovation Project (see panel) on a remote sensing technique that could aid the identification of REEs in rocks anywhere in the world. The project brings together expertise in remote sensing, geochemistry and mineralogy from both institutes to take advantage 
of the properties that make the metals so special.

“Despite their name, the rare earth elements are not particularly rare and are as abundant in the Earth’s crust as elements such as copper and tin,” explains Riley from BAS. “However, to be extractable in an economic way, they need to be concentrated into veins or sediments.” 
It’s the identification of these concentrations that is critical for the future security of supply. REEs all have an atomic structure that causes them to react to photons of light through a series of electronic transitions. This gives them the magnetic and electrical properties for which they are prized in plasma TVs, wind turbines and electric car batteries. And it also means that for every photon of light they absorb, they reflect other photons in a unique way – it is this property that the researchers have latched onto as a means of tracking them down.

“The light they reflect is so specific that it’s like a fingerprint, one that we can capture using sensors that pick up light emissions,” explains Gibson, from Cambridge’s Department of Earth Sciences. “The difficulty, however, is that in naturally occurring rocks and minerals, the rare earth element emission spectra are mixed up with those of other elements. It’s like looking at overlapping fingerprints – the challenge was to work out how to tease these spectral fingerprints apart.”

Gibson has over 20 years’ experience investigating how REEs are generated during the melting of the Earth’s mantle. “Collective understanding of the geological make-up of the world is now good enough that we know where to look for these rocks – at sites of a certain type of past tectonic activity – but even then it’s difficult to find them.”

Riley is the head of the Geological Mapping Group at BAS – his job is to “map the unmapped” areas of the polar region to understand the geological evolution of the continent. Much of his work depends on being able to develop new ways of interrogating satellite- and aircraft-based remote sensing data. “It became a frustration that we could collect data and say generally what was on the ground but that we couldn’t define individual fingerprints, and so we developed the analytical tools to do this.”

Gibson and Neave gathered rocks containing REE-bearing minerals from around the world – sourced from mining companies, museum collections and universities. One such source was the Harker Collection housed in the University’s Sedgwick Museum of Earth Sciences. This collection contains specimens of minerals and rocks rich in REEs that were collected decades previously by geologists who were unaware of their economic importance.

Neave analysed the emission spectrum of each rock and related this to its gross and microscopic composition. From this information he began to untangle the individual fingerprints, resulting in what the researchers believe is the most comprehensive ‘spectral database’ of REEs in their natural state – in rocks.

The next goal is to use this spectral database as a reference source to track down deposits from the air. “Although data from aircraft is now good enough to be analysed in this way, we are waiting for new satellite missions such as the German Environmental Mapping and Analysis Program (EnMAP) to be launched in the next few years,” explains Riley.The plan would then be to carry out reconnaissance sweeps of the most likely terrains and explore the possibility of mining these areas. “Our hope is that this research will help to create an internationally unique and competitive capability to map these surprisingly common – yet difficult to find – materials,” adds Gibson.

Aurora Cambridge

The search for rare earth elements is one of a host of ongoing projects between the University and BAS. Like these, a new centre – Aurora Cambridge – will reflect the ethos that innovation developed for the Antarctic is transferable to a global setting.

Aurora Cambridge aims to generate new research and entrepreneurial activity focused on climate change and challenging environments through academic, business and policy partnerships. It will be located at BAS in Cambridge and has been funded by the National Environment Research Council with support from the University.

The building is due to open in 2017; however, 27 University of Cambridge–BAS Joint Innovation Projects are already under way with funding from the Higher Education Funding Council for England – including the development of mapping technologies for rare earth elements led by Drs Sally Gibson and Teal Riley.

Other projects include research on cold-adapted enzymes with potential applications in the biotech industries, remote sensing for conservation of seabirds and marine mammals, and the measurement of coastal vulnerability through sea-level rise. Many involve external industrial partners and other research institutions as well as researchers from BAS and 12 University departments.

“The collaborative projects demonstrate not only the importance of research technology to the Antarctic but also their transferability beyond its shores to a global setting,” explains BAS Director of Innovation Dr Beatrix Schlarb-Ridley. “The SPECTRO-ICE project, for instance, has brought scientists at BAS who are concerned with monitoring the atmosphere above the ice cap together with physicists and mathematicians who are working hard to avoid seeing the atmosphere in their study of the stars – both use similar techniques and need to operate advanced instruments at difficult locations.”

“This is just the beginning,” says BAS Director Professor Jane Francis. “The new innovation centre will help us to extend the range of fruitful partnerships with academia, business, policy makers and the third sector to create tangible benefits for society.”

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

Chasing the volcano “A series of seismic shocks which preceded Iceland’s biggest volcanic eruption in 200 years”

Chasing the volcano-GeologyPage
Credit: University of Cambridge

In 2014, Cambridge researchers monitored a series of seismic shocks which preceded Iceland’s biggest volcanic eruption in 200 years. The dramatic story of their work, and its scientific value, is now part of this year’s Royal Society Summer Science Exhibition.

Faced with the prospect of an imminent volcanic eruption, most people would head for safety, but for one group of Cambridge research students, the aim is to get as close as they realistically can.

That opportunity suddenly presented itself when, on the night of August 28, 2014, members of the University’s Volcano Seismology group were shaken awake by a series of low-magnitude earthquakes. The tremors were being caused by the movement of an underground channel of molten rock which they had been tracking for 10 days as it forced its way north-east from the Barðarbunga volcano in central Iceland.

The group’s work involves measuring and studying such seismic events, which warn that a volcanic eruption may be about to take place. As it became clear that this was now imminent, the team hastily finished deploying field instruments around the tip of the area where they knew the channel was flowing. Just hours later, it ruptured the Earth’s surface, disgorging huge fountains of magma that reached up to 150 metres high, announcing the start of Iceland’s biggest volcanic event for 200 years.

The story of the group’s dramatic fieldwork – and why it matters – is now the subject of a display at this year’s Royal Society Summer Science Exhibition, which will be taking place in London from 4-10 July 2016.

During the build-up to the eruption, a total of 30,000 mini earthquakes occurred as the molten rock forged a crack through the earth, several kilometres beneath the surface. By analysing these earthquakes, the team were able to understand more about the physical process that was happening under their feet. This knowledge helps to inform both early warning tools that can be used to anticipate a volcanic eruption, and scenario-planning around its potential consequences.

Robert Green, a Seismology PhD student from St John’s College, University of Cambridge, was one of the Cambridge researchers responsible for assessing the tremors around Barðarbunga. “Most people think of a volcano as being a large mountain where molten rock comes straight up from under the ground and erupts directly from the summit, either explosively creating a huge ash cloud, or producing lava which flows down the sides,” he said.

“Those are certainly options, but this one was different. Instead the molten rock moved 46 kilometres underground away from the volcano before it emerged in a completely different place. When it did, the eruption formed a curtain of fire the height of Big Ben.”

Earthquakes such as those measured by Green and his colleagues are caused by the molten flow cracking through rock in the Earth’s crust. As the rocks slide past one another, they cause the ground to shake. In August 2014, it was this seismic activity that indicated that one of these so-called “dyke intrusions” had developed from the Barðarbunga volcano.

The scientific community was quick to respond, deploying researchers from 26 different institutions, including the Cambridge team. This group effectively chased the volcano, travelling in helicopters, snow scooters and offroad vehicles to install seismometers and track its subterranean progress.

They also worked closely with civil and aviation authorities to keep them up to date about potential impact. Airlines feared a repeat of the 2010 Eyjafjallajökull eruption, when a plume of volcanic ash infamously led to the cancellation of 100,000 flights during the Easter holidays.

When the fissure eruption finally happened, it was at the Holuhraun lava field, the site of a 19th Century volcanic event north of Barðarbunga itself. Some of the Cambridge group’s seismometers had been positioned so close that they had to be hastily retrieved in the face of the advancing lava flow.

The eruption was on a huge scale, lasting from August 2014 until February 2015. During its early stages, about 500 tonnes of rock were flung out of the Earth every second at temperatures of about 1,300 degrees C. The thermal energy was calculated to be equivalent to one Hiroshima atomic bomb being detonated every two minutes for almost six months.

For the researchers, it was an unprecedented opportunity to gather data about the effects of the movement of magma under the ground during such events. “Earthquakes accompanying the movement of magma underground are the best volcano monitoring tool we have, but we don’t yet understand the mechanics of it – precisely why, when and where the earthquakes occur, and why, when and where they don’t,” said Jenny Woods, another member of the team, based at Cambridge’s Department of Earth Sciences. “These are important things to learn if we want to understand the behaviour of volcanoes and improve eruption prediction.”

In the case of the 2014 eruption, scientists and government teams had to consider the possibility that lava might erupt beneath a local ice cap, causing an ash cloud which could disrupt flights, and a major flood. Even more frightening was the possibility was that it might continue moving until it met another reservoir of molten rock beneath the Askja volcano, triggering a major eruption that would have had devastating consequences for much of northern Iceland.

“There is no certainty during these events that it will even erupt at all,” Green added. “The whole time we were looking at several possible scenarios, one of which was that the lava would just stay in the ground.”

“Tracking the Bárdarbunga intrusion and witnessing the eruption was an utterly surreal experience: arriving in Iceland, deploying instruments in an evacuation zone, being shaken awake by an earthquake, and then being the first group on the scene at the eruption in the middle of the night under the northern lights,” said Woods. “It was a real reminder of the raw power trapped in the earth beneath our feet!”

The study also involved an assessment of the stress changes that occurred within the Earth’s crust as a result of the tremors. These findings could, among other things, help with the assessment of human activities that have a similar effect, not least the highly sensitive question of where and when it is safe to undertake “fracking” for shale gas.

The group’s display at the Royal Society Summer Exhibition, which is aptly entitled “Explosive Earth”, will feature several hands-on activities enabling visitors to discover how researchers monitor the movement of molten rock under the ground, how they triangulate the point of origin from tremors to track the magma’s course, and how an earthquake itself is measured.

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

Sand Ripples on Mars are a type not seen on Earth

sand ripples on Mars-GeologyPage
Two sizes of ripples are evident in this Dec. 13, 2015, view of a top of a Martian sand dune, from NASA’s Curiosity Mars rover. Sand dunes and the smaller type of ripples also exist on Earth. Credit: NASA

Some of the wind-sculpted sand ripples on Mars are a type not seen on Earth, and their relationship to the thin Martian atmosphere today provides new clues about the atmosphere’s history.

The determination that these mid-size ripples are a distinct type resulted from observations by NASA’s Curiosity Mars rover. Six months ago, Curiosity made the first up-close study of active sand dunes anywhere other than Earth, at the “Bagnold Dunes” on the northwestern flank of Mars’ Mount Sharp.

“Earth and Mars both have big sand dunes and small sand ripples, but on Mars, there’s something in between that we don’t have on Earth,” said Mathieu Lapotre, a graduate student at Caltech in Pasadena, California, and science team collaborator for the Curiosity mission. He is the lead author of a report about these mid-size ripples published in the July 1 issue of the journal Science.

Both planets have true dunes — typically larger than a football field — with downwind faces shaped by sand avalanches, making them steeper than the upwind faces.

Earth also has smaller ripples — appearing in rows typically less than a foot (less than 30 centimeters) apart — that are formed by wind-carried sand grains colliding with other sand grains along the ground. Some of these “impact ripples” corrugate the surfaces of sand dunes and beaches.

Images of Martian sand dunes taken from orbit have, for years, shown ripples about 10 feet (3 meters) apart on dunes’ surfaces. Until Curiosity studied the Bagnold Dunes, the interpretation was that impact ripples on Mars could be several times larger than impact ripples on Earth. Features the scale of Earth’s impact ripples would go unseen at the resolution of images taken from orbit imaging and would not be expected to be present if the meter-scale ripples were impact ripples.

“As Curiosity was approaching the Bagnold Dunes, we started seeing that the crest lines of the meter-scale ripples are sinuous,” Lapotre said. “That is not like impact ripples, but it is just like sand ripples that form under moving water on Earth. And we saw that superimposed on the surfaces of these larger ripples were ripples the same size and shape as impact ripples on Earth.”

Besides the sinuous crests, another similarity between the mid-size ripples on Mars and underwater ripples on Earth is that, in each case, one face of each ripple is steeper than the face on the other side and has sand flows, as in a dune. Researchers conclude that the meter-scale ripples are built by Martian wind dragging sand particles the way flowing water drags sand particles on Earth — a different mechanism than how either dunes or impact ripples form. Lapotre and co-authors call them “wind-drag ripples.”

“The size of these ripples is related to the density of the fluid moving the grains, and that fluid is the Martian atmosphere,” he said. “We think Mars had a thicker atmosphere in the past that might have formed smaller wind-drag ripples or even have prevented their formation altogether. Thus, the size of preserved wind-drag ripples, where found in Martian sandstones, may have recorded the thinning of the atmosphere.”

The researchers checked ripple textures preserved in sandstone more than 3 billion years old at sites investigated by Curiosity and by NASA’s Opportunity Mars rover. They found wind-drag ripples about the same size as modern ones on active dunes. That fits with other lines of evidence that Mars lost most of its original atmosphere early in the planet’s history.

Other findings from Curiosity’s work at the Bagnold Dunes point to similarities between how dunes behave on Mars and Earth.

“During our visit to the active Bagnold Dunes, you might almost forget you’re on Mars, given how similar the sand behaves in spite of the different gravity and atmosphere. But these mid-sized ripples are a reminder that those differences can surprise us,” said Curiosity Project Scientist Ashwin Vasavada, of NASA’s Jet Propulsion Laboratory in Pasadena.

After examining the dune field, Curiosity resumed climbing the lower portion of Mount Sharp. The mission is investigating evidence about how and when ancient environmental conditions in the area evolved from freshwater settings favorable for microbial life, if Mars has ever hosted life, into conditions drier and less habitable.

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

Plate tectonics without jerking

Plate tectonics without-GeologyPage

The earthquake distribution on ultraslow mid-ocean ridges differs fundamentally from other spreading zones. Water circulating at a depth of up to 15 kilometres leads to the formation of rock that resembles soft soap. This is how the continental plates on ultraslow mid-ocean ridges may move without jerking, while the same process in other regions leads to many minor earthquakes, according to geophysicists of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Their study is going to be published advanced online in the journal Nature on Wednesday, June 29, 2016.

Mountain ranges like the Himalayas rise up where continental plates collide. Mid-ocean ridges, where the continents drift apart, are just as spectacular mountain ranges, but they are hidden in the depths of the oceans. On the seabed, like on a conveyor belt, new ocean floor (oceanic lithosphere) is formed as magma rises from greater depths to the top, thus filling the resulting gap between the lithospheric plates. This spreading process creates jerks, and small earthquakes continuously occur along the conveyor belt. The earthquakes reveal a great deal about the origin and structure of the new oceanic lithosphere. On the so-called ultraslow ridges, the lithospheric plates drift apart so slowly that the conveyor belt jerks and stutters and, because of the low temperature, there is insufficient melt to fill the gap between the plates. This way, the earth’s mantle is conveyed to the seabed in many places without earth crust developing. In other locations along this ridge, on the other hand, you find giant volcanoes.

Ultraslow ridges can be found under the sea ice in the Arctic and south of Africa along the Southwest Indian Ridge in the notorious sea areas of the Roaring Forties and Furious Fifties. Because these areas are so difficult to access, earthquakes have not been measured there. And so until now, little was known about the structure and development of around 20 percent of the global seabed.

With the research vessel Polarstern, a reliable workhorse even in heavy seas, the researchers around Dr Vera Schlindwein of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have now for the first time risked deploying a network of ocean bottom seismometers (OBS) at the Southwest Indian Ridge in the Furious Fifties and recovered them a year later. At the same time, a second network was placed on a volcano in the more temperate latitudes of the Southwest Indian Ridge. “Our effort and our risk were rewarded with a unique set of earthquake data, which for the first time provides deep insights into the formation of the ocean floor when spreading rates are very slow,” explains AWI geophysicist Vera Schlindwein.

Her results turn current scientific findings on the functioning of ultra-slow mid-ocean ridges upside down: Schlindwein and her PhD student Florian Schmid found that water may circulate up to 15 kilometres deep in the young oceanic lithosphere, i.e. the earth crust and the outer part of the earth mantle. If this water comes into contact with rock from the earth mantle, a greenish rock called serpentinite forms. Even small quantities of ten percent serpentinite are enough for the rock to move without any earthquakes as if on a soapy track. The researchers discovered such aseismic areas, clearly confined by many small earthquakes, in their data.

Until now, scientists thought that serpentinite only forms near fault zones and near the surface. “Our data now suggest that water circulates through extensive areas of the young oceanic lithosphere and is bound in the rock. This releases heat and methane, for example, to a degree not previously foreseen,” says Vera Schlindwein.

The AWI geophysicists were now able to directly observe the active spreading processes using the ocean floor seismometers, comparing volcanic and non-volcanic ridge sections. “Based on the distribution of earthquakes, we are for the first time able to watch, so to speak, as new lithosphere forms with very slow spreading rates. We have not had such a data set from ultra-slow ridges before,” says Vera Schlindwein.

“Initially, we were very surprised that areas without earth crust show no earthquakes at all down to 15 kilometres depth, even though OBS were positioned directly above. At greater depths and in the adjacent volcanic areas, on the other hand, where you can find basalt on the sea floor and a thin earth crust is present, there were flurries of quakes in all depth ranges,” says Vera Schlindwein about her first glance at the data after retrieving the OBS with RV Polarstern in 2014.

The results also have an influence on other marine research disciplines: geologists think about other deformation mechanisms of the young oceanic lithosphere. Because rock that behaves like soft soap permits a completely different deformation, which could be the basis of the so-called “smooth seafloor” that is only known from ultra-slow ridges. Oceanographers are interested in heat influx and trace gases in the water column in such areas, which were previously thought to be non-volcanic and “cold.” Biologists are interested in the increased outflow of methane and sulphide on the sea floor that is to be expected in many areas and that represents an important basis of life for deep-sea organisms.

Reference:
Vera Schlindwein, Florian Schmid. Mid-ocean-ridge seismicity reveals extreme types of ocean lithosphere. Nature, 2016; DOI: 10.1038/nature18277

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

Crystal movement under Mount St. Helens may have indicated 1980 eruption was likely

Crystal movement under Mount St. Helens-GeologyPage
Mount St Helens volcano (Washington State, USA) in 2003 Credit: Jon Blundy

A study of how crystals moved in magma under the Mount Saint Helens volcano before the 1980 eruption may have signalled that an eruption was probable. Scientists say that similar measurements may indicate the possibility of eruption in some other, well-studied volcanoes, but caution that this is not a technique which could be applied to every volcano.

The eruption of Mount St Helens in Washington State, on 18th May 1989, was the most significant volcanic eruption in the contiguous United States in the last 100 years. The eruption column rose to 80,000 feet (24km) and deposited ash in 11 states. 57 people were killed as a direct result of the eruption. Since then, Mount Saint Helens has become one of the most studied volcanoes in the world, as scientists have tried to understand what caused the eruption.

Now a group of international researchers studying the movement of crystals in magma believes that they may have found signs that could indicate a risk of future eruptions at Mount St Helens, and possibly some other volcanoes. The work is presented at the Goldschmidt geochemistry conference in Yokohama, Japan.

According to lead researcher, Jon Blundy (University of Bristol):

“We looked for signs in the way zoned feldspar crystals grew and moved beneath Mount St Helens in the build-up to the 1980 eruption. Crystals in erupted volcanic rocks are made up of concentric layers, like rings of a tree. The crystal layers, just a few hair’s breadths across, have a distinct chemical composition that reflects the conditions under which they grew in the underground magma system prior to eruption. In other words, they can show where they were formed and the pressure and temperature conditions at the time of formation.

If you can read the record preserved in the zoned crystals, you can learn where and when molten magma has moved under the volcano. Rapid upwards movement of magma at depths of several km is a pretty good indication that something significant is happening. We have found a way of correlating the crystal composition to where they came from”.

The researchers found that in the 3 years immediately before the eruption, there was a significant movement of magma under Mount St Helens, which carried the crystals from 12km below the volcano to around 4 km below the volcano.

“This indicates that the magma system beneath the volcano had become destabilised, probably in the months to years before the eruption”, said Professor Blundy. “What we are doing is not a real-time monitoring, but a retrospective study of what happened prior to the last eruption. Now we have found this movement, it’s reasonable to assume that similar movement will precede any further eruptions from this and perhaps many other volcanoes”.

The researchers will continue to monitor Mount St Helens, but they hope to be able to begin to monitor the record of zoned feldspar crystals in the magma of other well-studied volcanoes, such as Uturuncu in Bolivia, Mt Pinatubo (Philippines), and Bezymianny (Russia). As Jon Blundy said: “There is probably no single factor which can predict when a volcano erupts. What we have found, namely destabilisation of deeply-stored magma and its ascent to shallow levels in the crust, may be one key factor, which may be especially useful in circumstances where we can monitor a volcano closely over a period of years”.

Commenting, Associate Professor Georg Zellmer (Massey University, New Zealand), said: “The study of chemical variations in crystals has become a key indicator of magmatic processes under active and dormant volcanoes. Refining the pressure-temperature-time resolution of this record is at the forefront of ongoing research in this field. The critical next step towards real-time volcanic hazard mitigation will be to link such data with geophysical volcano monitoring efforts”.

Reference:
‘The testimony of zoned crystals from volcanic rocks’ by Jon Blundy, Oleg Melnik, Natalia Gorokhova, Ralf Dohmen, presented at the Goldschmidt geochemistry conference “PDF”

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

Asteroid day will draw eyes to the stars, but the more urgent threat may be under our feet

Asteroid day will draw eyes-GeologyPage

June 30 is Asteroid Day, a global awareness effort to promote asteroids and discussion around what can be done to protect our planet from impacts, but there may be a more likely natural threat.

While an asteroid impact with Earth may make for great drama in the movies, no human in the past 1,000 years is known to have been killed by a meteorite or by the effects of one impacting our planet, according to NASA. That is just one reason Robert Mohr, Ph.D., instructor in the University of Alabama at Birmingham’s College of Arts & Sciences, says energies might be better spent on the super volcano under Yellowstone.

“If the Yellowstone super volcano erupts, it will take out anywhere from 20-30 percent of the continent,” Mohr said. “And the effects will be felt basically everywhere in the United States and in places beyond, potentially for years.”

Aside from giant asteroid strikes, super volcanoes are considered to be the most devastating of all natural disasters. Super volcanoes have been known to cause mass extinctions and long-term climate changes.

The last known super volcano eruption, believed to have occurred around 70,000 years ago on the site of today’s Lake Toba in Sumatra, Indonesia, caused a “volcanic winter” that blocked out the sun for six to eight years.

The super volcano that erupted in Wyoming 600,000 years ago, in what is now Yellowstone National Park, ejected more than 1,000 cubic meters of lava and ash into the atmosphere — enough to bury a large city several kilometers deep. By comparison, the 1991 eruption of Mount Pinatubo in the Philippines, which caused a 0.4 degree drop in average global temperature for the following year, was 100 times less forceful than the Yellowstone eruption.

“A Yellowstone eruption would alter life as we know it for a long time,” Mohr said. “Sunlight would be blocked for long periods of time, which would affect crop growth and food supply. Preparing for something like that, which is a lot closer to a likelihood than an asteroid’s hitting Earth, would seem to me to be more prudent.”

NASA knows of no asteroid or comet currently on a collision course with Earth. In fact, as far as the agency can tell, no large object is likely to strike the Earth any time in the next several hundred years. To be able to better calculate the statistics and narrow down concrete possibilities, astronomers need to detect as many of the near-Earth objects as possible — an exercise that is quite hard to achieve with asteroids.

Mohr knows some will disagree with the notion that a super volcano is a more worrisome threat, and he admits it would be “nice to know” if an asteroid were heading straight for us. But he says the likelihood of discovering any asteroid far ahead of impact is quite small.

“There is no easy way to find an asteroid,” he said. “It’s not like looking for Easter eggs in a defined yard. There’s a whole bunch of sky, and you’re looking for something extremely small and that doesn’t really give off a whole lot of light, so it doesn’t show itself well. Where the asteroid is going to be in the sky and the odds of your actually being able to take a telescope, point it at the asteroid and pick it out with all the other stuff you’re going to see in the telescope are very, very low — even if it’s right there.”

Note: The above post is reprinted from materials provided by University of Alabama at Birmingham. The original item was written by Tyler Greer.

Rare Dinosaur-Era Bird Wings Trapped in Amber

Rare Dinosaur-Era Bird Wings-GeologyPage
One of two fossil specimens showing the pale underside of the wing and the dark brown feathers on the leading edge. Credit: Royal Saskatchewan Museum/R.C. McKellar

Two tiny wings locked in amber 99 million years ago suggest that in the middle of the Cretaceous period — when dinosaurs still walked the planet — bird feathers already looked a lot like they do today.

A team of researchers led by Lida Xing, a palaeontologist at the China University of Geosciences in Beijing, recovered a first for the time period: a few cubic centimetres of amber from northeastern Myanmar that contained the partial remains of two bird wings. The specimens include bone, feathers and skin, according to a study published on 28 June in Nature Communications.

Prior evidence of bird plumage from the Cretaceous, which stretched from 145 million to 66 million years ago, came from 2D impressions left in sedimentary rocks and feathers that had been preserved in amber but that gave no skeletal clues to their species of origin.

“For the first time, we’re seeing the feathers associated with the skeletal materials,” says co-author Ryan McKellar, who studies fossils in amber as curator of invertebrate palaeontology at the Royal Saskatchewan Museum in Regina, Canada.

Minute details

The amber even preserved claw marks, signs that before it died, one of the birds had struggled against the sticky resin that had engulfed its wing.

The feathers retained their original colouring from pale dots and undersides to darker browns elsewhere, and on both wing fragments, the structures and arrangements of the feathers were similar to those seen in modern birds. The bones were smaller than a hummingbird’s and incompletely developed. This suggests that the wings belonged to hatchlings, probably of enantiornithine birds — a primitive group that had teeth and clawed wings, and that went extinct at the same time as the dinosaurs, 66 million years ago.

However, the feathers themselves were more like those of adults and showed no signs that they had moulted — suggesting they had developed quickly and skipped the downy juvenile stage of modern birds entirely. “They’re basically hatching, and ready to go,” says McKellar.

Peter Makovicky, a curator at the Field Museum in Chicago, Illinois, who studies dinosaurs, says that these finds will help to reduce some of the detective work needed to infer a 3D structure from 2D fossils.

“The colour patterns are preserved; the exact arrangement of feathers in three dimensions relative to the bone are preserved,” he says. “It’s fantastic because you get so much more detail.”

Reference:
Lida Xing, Ryan C. McKellar, Min Wang, Ming Bai, Jingmai K. O’Connor, Michael J. Benton, Jianping Zhang, Yan Wang, Kuowei Tseng, Martin G. Lockley, Gang Li, Weiwei Zhang & Xing Xu. Mummified precocial bird wings in mid-Cretaceous Burmese amber. DOI:10.1038/ncomms12089

Note: The above post is reprinted from materials provided by Nature. The original article was written by Rachel Becker.

Previously unknown global ecological disaster discovered

Previously unknown global-GeologyPage
Approximately 500,000 years after the major natural disaster at the boundary between the Permian and the Triassic another event altered the vegetation fundamentally and for longer. Credit: Graphic UZH

There have been several mass extinctions in the history of Earth with adverse consequences for the environment. Researchers from the University of Zurich have now uncovered another disaster that took place around 250 million years ago and completely changed the prevalent vegetation during the Lower Triassic.

There have been several mass extinctions in the history of Earth. One of the largest known disasters occurred around 252 million years ago at the boundary between the Permian and the Triassic. Almost all sea-dwelling species and two thirds of all reptiles and amphibians died out. Although there were also brief declines in diversity in the plant world, they recovered in the space of a few thousand years, which meant that similar conditions to before prevailed again.

Change in flora within a millennia

Researchers from the Institute and Museum of Paleontology at the University of Zurich have now discovered another previously unknown ecological crisis on a similar scale in the Lower Triassic. The team headed by Peter A. Hochuli and Hugo Bucher revealed that another event altered the vegetation fundamentally and for longer approximately 500,000 years after the major natural disaster at the boundary between the Permian and the Triassic.

The scientists studied sediments towering over 400 meters high from North-Eastern Greenland. Carbon isotope curves suggest that the prevalent seed ferns and conifers were replaced by spore plants in the space of a few millennia. To this day, certain spore plants like ferns are still famous for their ability to survive hostile conditions better than more highly developed plants.

Catastrophic ecological upheaval changes plant world

Until now, it was assumed that the environment gradually recovered during the Lower Triassic 252.4 to 247.8 million years ago. “The drastic, simultaneous changes in flora and the composition of the carbon isotopes indicate that the actual upheaval in the vegetation didn’t take place until the Lower Triassic, i.e. around 500,000 years later than previously assumed,” explains Hochuli.

The researchers didn’t just observe the mass death of vegetation in Greenland; they already discovered the first indications of this floral shift a few years ago in sediment samples from Pakistan. Moreover, the latest datings of volcanic ash by Australian scientists show that the most significant change in the plant world did not happen until a few millennia after the Permian/Triassic boundary. During this period, the indigenous glossopteris seed plant group died out, an event that had previously been dated back to the Permian. Thanks to these findings, the sediment sequences of the supercontinent Gondwana in the southern hemisphere now need to be reinterpreted.

Crisis probably triggered by volcanic eruptions

What caused this newly described natural disaster remains unclear. “However, we see a link between this previously unknown global event and the enormous volcanic eruptions we know from the Lower Triassic in what’s now Siberia,” explains Bucher, Director of UZH’s Institute and Museum of Paleontology.

Reference:
Peter A. Hochuli, Anna Sanson-Barrera, Elke Schneebeli-Hermann, Hugo Bucher. Severest crisis overlooked—Worst disruption of terrestrial environments postdates the Permian–Triassic mass extinction. Scientific Reports, 2016; 6: 28372 DOI: 10.1038/srep28372

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

Our ancestors evolved faster after dinosaur extinction

Our ancestors evolved faster-GeologyPage

Our ancestors evolved three times faster in the 10 million years after the extinction of the dinosaurs than in the previous 80 million years, according to UCL researchers.

The team found the speed of evolution of placental mammals—a group that today includes nearly 5000 species including humans—was constant before the extinction event but exploded after, resulting in the varied groups of mammals we see today.

Lead researcher, Dr Thomas Halliday (UCL Genetics, Evolution & Environment), said: “Our ancestors—the early placental mammals – benefitted from the extinction of non-avian dinosaurs and dwindling numbers of competing groups of mammals. Once the pressure was off, placental mammals suddenly evolved rapidly into new forms.

“In particular, we found a group called Laurasiatheria quickly increased their body size and ecological diversity, setting them on a path that would result in a modern group containing mammals as diverse as bats, cats, rhinos, whales, cows, pangolins, shrews and hedgehogs.”

The team found that the last common ancestor for all placental mammals lived in the late Cretaceous period, about three million years before the non-avian dinosaurs became extinct 66 million years ago. This date is 20 million years younger than suggestions from previous studies which used molecular data from living mammals and assumed a near-constant rate of evolution.

In this study, funded by the Natural Environment Research Council and published today in Proceedings B of the Royal Society, the researchers analysed fossils from the Cretaceous to the present day, and used the dates of their occurrence in the fossil record to estimate the timing of divergences based on an updated tree of life. The new tree was released by the same team in 2015 and has the largest representation of Paleocene mammals to date.

The scientists measured all the small changes in the bones and teeth of 904 placental fossils and mapped the anatomical differences between species on the tree of life. From measuring the number of character changes over time for each branch, they found the average rate of evolution for early placental mammals both before and after the dinosaur extinction event. They compared the average rate of evolution over the geological stages before the extinction and the geological stages after to see what impact it had.

Senior author, Professor Anjali Goswami (UCL Genetics, Evolution & Environment and UCL Earth Sciences), said: “Our findings refute those of other studies which overlooked the fossils of placental mammals present around the last mass extinction. Using rigorous methods, we’ve successfully tracked the evolution of early placental mammals and reconstructed how it changed over time. While the rate differed between species, we see a clear and massive spike in the rates of evolution straight after the dinosaurs become extinct, suggesting our ancestors greatly benefitted from the demise of the dinosaurs. The huge impact of the dinosaur extinction on the evolution of our ancestors really shows how important this event was in shaping the modern world.”

Professor Paul Upchurch (UCL Earth Sciences), co-author of the study, added: “Our large and refined data set allows us to build a clearer picture of evolutionary history. We plan on using it to study other large-scale evolutionary patterns such as how early placental mammals dispersed across the continents via land bridges that no longer exist today.”

Reference:
Eutherians experienced elevated evolutionary rates in the immediate aftermath of the K-Pg mass extinction, Proceedings of the Royal Society B, DOI: 10.1098/rspb.2015.3026

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

What happens when you steam a planet?

What happens when-GeologyPage
Washington University in St. Louis cosmochemists show that hot, rocky exoplanets with steam atmospheres may vaporize some of their rocky elements and then lose them to space, changing the bulk composition of the planet. Credit: NASA

The media often imply that the goal of the hunt for extrasolar planets is to find a rocky planet about the size of Earth orbiting a star like the sun at a distance that would allow liquid water to persist on its surface. In other words, the goal is to find Earth 2.0.

But there are reasons to be interested in the other worlds even if they couldn’t possibly harbor life. The hot, rocky planets, for example, offer rare and precious clues to the character and evolution of the early Earth.

The Kepler satellite has detected more than 100 hot, rocky planets orbiting close to their stars. If these planets formed from interstellar clouds with Earth-like abundances of volatile elements, like hydrogen, water and carbon dioxide, these planets might have steam atmospheres.

Steaming a rocky planet wouldn’t just press out the wrinkles. Because the rock-forming elements dissolve in steam to different extents, steaming could, in principle, alter the planet’s bulk composition, density and internal structure, especially if all or part of the rock-bearing steam atmosphere was then lost to space.

Bruce Fegley and Katharina Lodders-Fegley, respectively professor and research professor in earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, published models of the chemistry of a steam atmosphere in equilibrium with a magma ocean at various temperatures and pressures in the June 20, 2016 issue of the Astrophysical Journal.

Based on their findings, they have some suggestions for planet hunters — things they might see when they train their telescopes on the hot rocks.

Getting some steam up

The fact that planet hunters have discovered many hot rocks roughly the size of Earth is one of three lines of evidence that come together in this research, Fegley said. The other two are the solubility of silica and other rock-forming elements in steam, and the idea that the early Earth had a steam atmosphere.

The notion that rocks will dissolve in steam may seem outlandish, but it is common knowledge among geologists. “Geologists are mainly concerned with very hot water or water and steam mixtures, whereas we’re looking at pure steam and temperatures hundreds of degrees hotter. But it’s the same kind of idea,” Fegley said.

The suspicion that the early Earth had a steam atmosphere goes back to 1974, when Gustave Arrhenius of the Scripps Institute of Oceanography argued that planetesimals that smacked into the forming Earth got hot enough to melt and release all their volatiles into the atmosphere.

The first to model the steam atmosphere of the early Earth were Yutaka Abe and Takafumi Matsui of the University of Tokyo in 1985. “They were mainly interested in the physics of the problem,” Fegley said, “and whether greenhouse gases acting as a thermal blanket would keep the surface molten. I think we’re the first ones to do a detailed chemistry on it.”

Escaping steam

Fegley and Lodders looked particularly at magnesium, silicon and iron, the three most abundant elements in material that combine with oxygen to form rock — both on Earth and the other terrestrial planets and probably on exoplanets orbiting stars with a composition like our sun’s.

The rocky elements enter the atmosphere as hydroxides (Si(OH)4, Fe(OH)2, and Mg (OH)2). Because these oxides have different solubilities in steam, cooking a planet in steam can change its major-element chemistry.

“Potassium, for example, easily goes into steam and if it’s lost, you’ll lose its radioactive isotope and so change the heat production on the planet,” Fegley said.

“If you dissolve more silicon than magnesium, and some of the atmosphere is lost, you can change the ratio of these elements in the planets. This might explain why the ratio of silicon to magnesium in the Earth is about 15 percent smaller than the ratio in the sun, even though the two formed from the same interstellar cloud,” he said.

“If you boil off a lot of the silicon, you might end up with a much denser planet than you’d expect. We’ve found some pretty dense exoplanets,” Fegley said. “Sometimes it’s crazy high. Earth is about 5.51 g/cm3, but Corot-7b is closer to 10 g/cm3 . . . high enough that it’s kind of hard to explain.

“And if you don’t lose the atmosphere, when the atmosphere cools down, the rock-forming elements would precipitate out. Since silicon is the rocky element most soluble in steam, it will be the most abundant, and you’ll get a silicate-rich-crust ready-made,” he said.

What to look for

Although the scientists are experimenting with numerical models, they remark that their conclusions are testable by observation.

“We’re hoping astrophysicists doing mass/radius diagrams to figure out the internal composition of planets will consider compositions other than Earth’s,” Fegley said.

“We’re also hoping space-based spectrometers will be trained on the hot, rocky planets. Astrophysicists see silicon, magnesium and sodium coming off the atmospheres of hot Jupiters and hot Neptunes but not yet off of hot rocks, which are dimmer and harder to observe,” Fegley said.

Intense ultraviolet light from nearby stars is likely to break up hydroxide molecules at the top of atmospheres, the scientists said. The “photoproducts” of these reactions, such as monatomic gases of aluminum, calcium, iron, magnesium and silicon, might be easier to see both because of their abundances and because their spectral lines are less likely be masked by other emissions.

Reference:
Bruce Fegley Jr., Nathan S. Jacobson, K. B. Williams, J. M. C. Plane, L. Schaefer, and Katharina Lodders. SOLUBILITY OF ROCK IN STEAM ATMOSPHERES OF PLANETS. DOI: 10.3847/0004-637X/824/2/103

Note: The above post is reprinted from materials provided by Washington University in St. Louis.

Caryodaphnopsis Originates in Late Cretaceous Laurasia

Caryodaphnopsis Originates-GeologyPage
Caryodaphnopsis burgeri Leaf Credit: Rolando Pérez/Smithsonian Institution

Caryodaphnopsis is a small genus of the Lauraceae. It contains 16 known species with a disjunct tropical amphi-Pacific distribution; 8 species in tropical Asia and 8 species in tropical America. Prof. LI Jie and his team of Xishuangbanna Tropical Botanical Garden (XTBG) previously investigated the phylogeny of the Persea group (Lauraceae) and its amphi-Pacific disjunction using the LEAFY gene. Their study indicated that the second intron of LEAFY was an excellent molecular marker for resolving phylogenetic relationships at lower taxonomic levels in Lauraceae due to its relatively high level of variation.

In a recent study, they chose RPB2 and LEAFY along with the universal ITS as molecular markers for phylogenetic reconstruction of the genus Caryodaphnopsis. They aimed to explore the phylogenetic utility of RPB2 and LEAFY in Caryodaphnopsis and related Lauraceae; and to place Caryodaphnopsis phylogenetically within the family. They further wanted to investigate the biogeographic history of Caryodaphnopsis focusing on its tropical amphi-Pacific distribution.

The researchers analyzed RPB2, LEAFY and ITS sequences of 9 Caryodaphnopsis species and 22 other Lauraceae species with maximum parsimony and Bayesian inference. They employed the Bayesian Markov chain Monte Carlo method to estimate the divergence time under a relaxed clock. By using both the statistical dispersal-vicariance analysis and likelihood approach under the dispersal-extinction-cladogenesis model, they conducted ancestral area reconstructions.

The phylogenetic analysis showed that the monophyly of Caryodaphnopsis was strongly supported. Within the Caryodaphnopsis clade, the Asian and American species each formed well-supported clades. The divergence of Caryodaphnopsis from the rest of Lauraceae was estimated as about 96.8 million years. The estimated divergence time between Asian and American Caryodaphnopsis was about 48 million years.

Based on the results, the researchers suggested that Caryodaphnopsis originated in Late Cretaceous Laurasia and its amphi-Pacific disjunction resulted from the disruption of ancestral boreotropical lineages between Eurasia and North America during the first cooling period of the Eocene.

The study entitled “Phylogeny and biogeography of Caryodaphnopsis (Lauraceae) inferred from low-copy nuclear gene and ITS sequences” has been published online in Taxon.

Reference:
Li, Lang; Madriñán, Santiago; Li, Jie, Phylogeny and biogeography of Caryodaphnopsis (Lauraceae) inferred from low-copy nuclear gene and ITS sequences. DOI: 10.12705/653.1

Note: The above post is reprinted from materials provided by Chinese Academy of Sciences.

Opal discovered in Antarctic meteorite

Opal discovered in-GeologyPage

Planetary scientists have discovered pieces of opal in a meteorite found in Antarctica, a result that demonstrates that meteorites delivered water ice to asteroids early in the history of the solar system. Led by Professor Hilary Downes of Birkbeck College London, the team announce their results at the National Astronomy Meeting in Nottingham on Monday 27 June.

Opal, familiar on Earth as a precious stone used in jewellery, is made up of silica (the major component of sand) with up to 30% water in its structure, and has not yet been identified on the surface of any asteroid. Before the new work, opal had only once been found in a meteorite, as a handful of tiny crystals in a meteorite from Mars.

Downes and her team studied the meteorite, named EET 83309, an object made up of thousands and broken pieces of rock and minerals, meaning that it originally came from the broken up surface, or regolith, of an asteroid. Results from other teams show that while the meteorite was still part of the asteroid, it was exposed to radiation from the Sun, the so-called solar wind, and from other cosmic sources. Asteroids lack the protection of an atmosphere, so radiation hits their surfaces all the time.

EET 83309 has fragments of many other kinds of meteorite embedded in it, showing that there were many impacts on the surface of the parent asteroid, bringing pieces of rock from elsewhere in the solar system. Downes believes one of these impacts brought water ice to the surface of the asteroid, allowing the opal to form.

She comments: “The pieces of opal we have found are either broken fragments or they are replacing other minerals. Our evidence shows that the opal formed before the meteorite was blasted off from the surface of the parent asteroid and sent into space, eventually to land on Earth in Antarctica.”

“This is more evidence that meteorites and asteroids can carry large amounts of water ice. Although we rightly worry about the consequences of the impact of large asteroid, billions of years ago they may have brought the water to the Earth and helped it become the world teeming with life that we live in today.”

The team used different techniques to analyse the opal and check its composition. They see convincing evidence that it is extra-terrestrial in origin, and did not form while the meteorite was sitting in the Antarctic ice. For example, using the NanoSims instrument at the Open University, they can see that although the opal has interacted to some extent with water in the Antarctic, the isotopes (different forms of the same element) match the other minerals in the original meteorite.

Note: The above post is reprinted from materials provided by Royal Astronomical Society (RAS).

Mercury’s origins traced to rare meteorite

Mercury's origins traced-GeologyPage
An image, taken by MESSENGER during its Mercury flyby on Jan. 14, 2008, of Mercury’s full crescent. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Around 4.6 billion years ago, the universe was a chaos of collapsing gas and spinning debris. Small particles of gas and dust clumped together into larger and more massive meteoroids that in turn smashed together to form planets. Scientists believe that shortly after their formation, these planets — and particularly Mercury — were fiery spheres of molten material, which cooled over millions of years.

Now, geologists at MIT have traced part of Mercury’s cooling history and found that between 4.2 and 3.7 billion years ago, soon after the planet formed, its interior temperatures plummeted by 240 degrees Celsius, or 464 degrees Fahrenheit.

They also determined, based on this rapid cooling rate and the composition of lava deposits on Mercury’s surface, that the planet likely has the composition of an enstatite chondrite — a type of meteorite that is extremely rare here on Earth.

Timothy Grove, the Cecil and Ida Green Professor of Geology in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, says new information on Mercury’s past is of interest for tracing Earth’s early formation.

“Here we are today, with 4.5 billion years of planetary evolution, and because the Earth has such a dynamic interior, because of the water we’ve preserved on the planet, [volcanism] just wipes out its past,” Grove says. “On planets like Mercury, early volcanism is much more dramatic, and [once] they cooled down there were no later volcanic processes to wipe out the early history. This is the first place where we actually have an estimate of how fast the interior cooled during an early part of a planet’s history.”

Grove and his colleagues, including researchers from the University of Hanover, in Germany; the University of Liége, in Belgium; and the University of Bayreuth, in Germany, have published their results in Earth and Planetary Science Letters.

Compositions in craters

For their analysis, the team utilized data collected by NASA’s MESSENGER spacecraft. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) probe orbited Mercury between 2011 and 2015, collecting measurements of the planet’s chemical composition with each flyby. During its mission, MESSENGER produced images that revealed kilometer-thick lava deposits covering the entire planet’s surface.

An X-ray spectrometer onboard the spacecraft measured the X-ray radiation from the planet’s surface, produced by solar flares on the sun, to determine the chemical composition of more than 5,800 lava deposits on Mercury’s surface.

Grove’s co-author, Olivier Namur of the University of Hanover, recalculated the surface compositions of all 5,800 locations, and correlated each composition with the type of terrain in which it was found, from heavily cratered regions to those that were less impacted. The density of a region’s craters can tell something about that region’s age: The more craters there are, the older the surface is, and vice versa. The researchers were able to correlate Mercury’s lava composition with age and found that older deposits, around 4.2 billion years old, contained elements that were very different from younger deposits that were estimated to be 3.7 billion years old.

“It’s true of all planets that different age terrains have different chemical compositions because things are changing inside the planet,” Grove says. “Why are they so different? That’s what we’re trying to figure out.”

A rare rock, 10 standard deviations away

To answer that question, Grove attempted to retrace a lava deposit’s path, from the time it melted inside the planet to the time it ultimately erupted onto Mercury’s surface.

To do this, he started by recreating Mercury’s lava deposits in the lab. From MESSENGER’s 5,800 compositional data points, Grove selected two extremes: one representing the older lava deposits and one from the younger deposits. He and his team converted the lava deposits’ element ratios into the chemical building blocks that make up rock, then followed this recipe to create synthetic rocks representing each lava deposit.

The team melted the synthetic rocks in a furnace to simulate the point in time when the deposits were lava, and not yet solidified as rock. Then, the researchers dialed the temperature and pressure of the furnace up and down to effectively turn back the clock, simulating the lava’s eruption from deep within the planet to the surface, in reverse.

Throughout these experiments, the team looked for tiny crystals forming in each molten sample, representing the point at which the sample turns from lava to rock. This represents the stage at which the planet’s solid rocky core begins to melt, creating a molten material that sloshes around in Mercury’s mantle before erupting onto the surface.

The team found a surprising disparity in the two samples: The older rock melted deeper in the planet, at 360 kilometers, and at higher temperatures of 1,650 C, while the younger rock melted at shallower depths, at 160 kilometers, and 1,410 C. The experiments indicate that the planet’s interior cooled dramatically, over 240 degrees Celsius between 4.2 and 3.7 billion years ago — a geologically short span of 500 million years.

“Mercury has had a huge variation in temperature over a fairly short period of time, that records a really amazing melting process,” Grove says.

The researchers determined the chemical compositions of the tiny crystals that formed in each sample, in order to identify the original material that may have made up Mercury’s interior before it melted and erupted onto the surface. They found the closest match to be an enstatite chondrite, an extremely rare form of meteorite that is thought to make up only about 2 percent of the meteorites that fall to Earth.

“We now know something like an enstatite chondrite was the starting material for Mercury, which is surprising, because they are about 10 standard deviations away from all other chondrites,” Grove says.

Grove cautions that the group’s results are not set in stone and that Mercury may have been an accumulation of other types of starting materials. To know this would require an actual sample from the planet’s surface.

“The next thing that would really help us move our understanding of Mercury way forward is to actually have a meteorite from Mercury that we could study,” Grove says. “That would be lovely.”

Note: The above post is reprinted from materials provided by Massachusetts Institute of Technology. The original item was written by Jennifer Chu.

ChemCam findings hint at oxygen-rich past on Mars

ChemCam findings-GeologyPage
The Curiosity rover examines the Kimberley formation in Gale crater, Mars. In front of the rover are two holes from the rover’s sample-collection drill and several dark-toned features that have been cleared of dust (see inset images). These flat features are erosion-resistant fracture fills that are composed of manganese oxides, which require abundant liquid water and strongly oxidizing conditions to form. The discovery of these materials suggests that the Martian atmosphere might once have contained higher abundances of free oxygen than in the present day. Credit: MSSS/JPL/NASA (PIA18390)

The discovery of manganese oxides in Martian rocks might tell us that the Red Planet was once more Earth-like than previously believed. A new paper in Geophysical Research Letters reveals that NASA’s Curiosity rover observed high levels of manganese oxides in Martian rocks, which could indicate that higher levels of atmospheric oxygen once existed on our neighboring planet. This hint of more oxygen in Mars’ early atmosphere adds to other Curiosity findings–such as evidence of ancient lakes–revealing how Earth-like our neighboring planet once was.

“The only ways on Earth that we know how to make these manganese materials involve atmospheric oxygen or microbes,” said Nina Lanza, a planetary scientist at Los Alamos National Laboratory and lead author on the study published in the American Geophysical Union’s journal. “Now we’re seeing manganese-oxides on Mars and wondering how the heck these could have formed.”

Lanza uses the Los Alamos-developed ChemCam instrument that sits atop Curiosity to “zap” rocks on Mars and analyze their chemical make-up. This work stems from Los Alamos National Laboratory’s experience building and operating more than 500 spacecraft instruments for national defense, giving the Laboratory the expertise needed to develop discovery-driven instruments like ChemCam. In less than four years since landing on Mars, ChemCam has analyzed roughly 1,500 rock and soil samples.

Microbes seem a far-fetched explanation for the manganese oxides at this point, said Lanza, but the idea that the Martian atmosphere contained more oxygen in the past than it does now seems possible. “These high-manganese materials can’t form without lots of liquid water and strongly oxidizing conditions,” said Lanza “Here on Earth, we had lots of water but no widespread deposits of manganese oxides until after the oxygen levels in our atmosphere rose due to photosynthesizing microbes.”

In the Earth’s geological record, the appearance of high concentrations of manganese is an important marker of a major shift in our atmosphere’s composition, from relatively low oxygen abundances to the oxygen-rich atmosphere we see today. The presence of the same types of materials on Mars suggests that something similar happened there. If that’s the case, how was that oxygen-rich environment formed?

“One potential way that oxygen could have gotten into the Martian atmosphere is from the breakdown of water when Mars was losing its magnetic field,” said Lanza. “It’s thought that at this time in Mars’ history, water was much more abundant.” Yet without a protective magnetic field to shield the surface from ionizing radiation, that radiation started splitting water molecules into hydrogen and oxygen. Because of Mars’ relatively low gravity, it wasn’t able to hold onto the very light hydrogen atoms, but the heavier oxygen atoms remained behind. Much of this oxygen went into the rocks, leading to the rusty red dust that covers the surface today. While Mars’ famous red iron oxides require only a mildly oxidizing environment to form, manganese oxides require a strongly oxidizing environment. These results suggest that past conditions were far more oxidizing (oxygen-rich) than previously thought.

“It’s hard to confirm whether this scenario for Martian atmospheric oxygen actually occurred,” Lanza added. “But it’s important to note that this idea represents a departure in our understanding for how planetary atmospheres might become oxygenated.” So far, abundant atmospheric oxygen has been treated as a so-called biosignature, or a sign of existing life.

The next step in this work is for scientists to better understand the signatures of non-biogenic versus biogenic manganese, which is directly produced by microbes. If it’s possible to distinguish between manganese oxides produced by life and those produced in a non-biological setting, that knowledge can be directly applied to Martian manganese observations to better understand their origin.

The high-manganese materials were found in mineral-filled cracks in sandstones in the Kimberley region of Gale crater, which the Curiosity rover has been exploring for the last four years. But that’s not the only place on Mars that abundant manganese has been found. The Opportunity rover, which has been exploring Mars since 2004, also recently discovered high-manganese deposits in its landing site thousands of miles from Curiosity, which supports the idea that the conditions needed to form these materials were present well beyond Gale crater.

Reference:
Oxidation of manganese in an ancient aquifer, Kimberley formation, Gale crater, Mars. DOI: 10.1002/2016GL069109

Note: The above post is reprinted from materials provided by DOE/Los Alamos National Laboratory.

Natural Diamond Colors

Natural Diamond Colors

Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells.

Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth’s mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth’s surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites. Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earth’s mantle. An alternative, and completely different growth technique is chemical vapor deposition (CVD). Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have been developed to distinguish natural diamonds, synthetic diamonds, and diamond simulants.

A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond’s coloration, a diamond’s color can either detract from or enhance its value. For example, most white diamonds are discounted in price when more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. Of all colored diamonds, red diamonds are the rarest. The Aurora Pyramid of Hope displays a spectacular array of naturally colored diamonds, including red diamonds.

Diamond Colors

Diamonds occur in a variety of colors; steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Colored diamonds contain interstitial impurities or structural defects that cause the coloration, whilst pure diamonds are perfectly transparent and colorless.

Brown Diamonds

Brown diamonds are the most common color variety of natural diamonds. The brown color makes them less attractive as gemstones because of the reduced glimmer, and most are used for industrial purposes. However, improved marketing programs, especially in Australia and the United States, have resulted in brown diamonds becoming valued as gemstones in recent years and even referred to as chocolate diamonds.

A significant portion of the output of Australian diamond mines is brown stones. A large amount of scientific research has gone into understanding the origin of the brown color. Several causes have been identified, including irradiation treatment, nickel impurities and lattice defects associated with plastic deformation; the latter is considered as the predominant cause, especially in pure diamonds. A high-pressure high-temperature treatment has been developed that heals lattice defects and converts brown diamonds into yellow or even colorless stones.

Orange Diamonds

The vast majority of all diamonds contain some nitrogen. In orange diamonds the nitrogen atoms have grouped themselves in a very specific way. This happens during and right after the diamond is formed. These nitrogen arrangements absorb light in the blue and yellow region of the spectrum producing an orange color. Orange Diamonds may contain a brown, yellow or pinkish modifying color.

The majority of orange diamonds come from Africa. The interest in this color surged in 1997 with the auction of the Pumpkin Diamond, so named by the buyer Ronald Winston as it was purchased the day before Halloween. The 5.54 carat vivid orange diamond, was at the time the largest vivid orange diamond ever found.

Yellow Diamonds

Yellow diamonds the nitrogen atoms have grouped themselves in very specific ways. This happens during and right after the diamond is formed. These nitrogen arrangements absorb light in the blue region of the spectrum producing a yellow color. Yellow diamonds can contain an orange, green or brown modifying color.

The most notably large and intense yellow diamonds have been discovered primarily in South Africa. The Allnatt, a 101ct cushion shape fancy vivid yellow diamond is perhaps the most signifi cant yellow diamond in history, named after its original owner Major Allnatt in the 1950s. One of the largest polished diamonds in the world is the Incomparable, a 407ct internally flawless brownish yellow diamond.

Green Diamonds

Green diamonds acquire their color after their trip to the earths surface when they rest in the ground near naturally occurring radiation. This radiation pushes into the diamond causing absorption in the red and yellow regions of the spectrum producing a green color. Green Diamonds can contain a yellowish, bluish or grayish modifying color.

Green diamonds are found predominately in regions of Africa and South America. The Dresden Green is the most famous green diamond. Weighing approximately 41 carats, it is often referred to as the cousin of the Hope Diamond for its historical importance. predominately in regions of Africa and South America. The Dresden diamond. Weighing approximately 41 carats, it is often referred to as the cousin of the Hope Diamond.

Blue Diamonds

The bonding of boron to carbon causes absorption in the red, yellow and green parts of the spectrum producing a blue color. Blue Diamonds may contain a gray, violet or greenish modifying color.

The Cullinan mine and Golconda region are the most notable areas where blue diamonds have come from. The most famous blue diamond in history is the 45 carat Hope Diamond. In 2008 The Wittelsbach Diamond, a 35.56 carat ushion-shaped fancy deep blue, was purchased at auction for $24 million. Experts compare this stones color and characteristics to the famed Hope Diamond.

Pink Diamonds

Diamonds become pink when heat and pressure deep within the earth cause the crystal lattice to distort. These distortions cause Pink Diamonds to absorb green light and hence impart a pink color. This can often be seen as in parallel bands within the diamond. Pink Diamonds may be modifi ed by an orange, brown or purplish color.

Pink diamonds can be graded faint, very light, light, fancy light, fancy intense, fancy deep and fancy vivid. And like other hues, the stronger the color, the higher the price tag.

Pink diamonds often feature secondary hues – an additional modifying color. The most common modifying colors are orange, brown and purple.

Natural pink diamonds can be found in Brazil, Russia, Siberia, South Africa, Tanzania and Canada. However, the majority of these breathtaking stones hail from the Argyle Mine in Australia, which is owned by Rio Tinto. The firm’s headquarters is also in Perth, Western Australia.

Here, the finest quality pink diamonds from the Argyle mine are cut and polished before they are sold via an exclusive tender. For proportions and to understand the rarity of pink diamonds, out of every 1 million carats of rough diamonds that the mine produces, just 1 carat is suitable to sell.

Red Diamonds

Red diamonds are extremely rare. Basically they are very strongly and deeply colored pink diamonds, with the same cause of color, crystal distortion. This combination is so rare that most jeweler and diamond dealers have never even seen a natural red diamond. They do not get large with the 5.11 carat Moussiaf Red shield being the largest known red.

Purple Diamonds

Purple diamonds are very rare. It is believed that they have a similar cause of color as pink diamonds; crystal distortion. They are most often found in Siberia and are generally small in size. There are no historical or famous purple diamonds. This may be due to their inhospitable location. Purple diamonds larger than 5 carats are extremely rare, and their color rarely reaches the intense and vivid color grades.

Violet Diamonds

Violet diamonds are very rare. The vast majority come from the Argyle mine, the same mine that most strongly colored pink diamonds are found. Their color is related to Hydrogen, but the exact mechanism is as yet unknown. They are often very small and diamonds greater than 1 carat are extremely rare. Their color usually has a gray component, diamonds of a pure violet color represent less than 10% of all violets. The number of intense and vivid violet diamonds mined each year could be counted on one hand.

Olive Diamonds

Olive diamonds are often confused with green diamonds, but they populate a different and discrete area of color space. Their color is a combination of yellow and green sometimes also a bit of brown or gray. They often come with three colors to describe them such as brownish greenish Yellow, and while this does accurately describe the color olive is a simpler, more concise term. They can range is size from small to large (some are 10+ carats). Occasionally they exhibit a color change when heated or left in the dark, these are known as chameleon diamonds.

Black Diamonds

Natural color black diamonds are rare. Their color is due to dark inclusions within the diamond, usually made up of graphite. It is rare that they are large, but the most famous black diamond, the Black Orloff, is 67.50 carats. Usually they are opaque and much of their beauty is the bright, adamantine luster that reflects light off the surface. Often used as melee in fashion jewelry in combination with colorless diamonds black diamonds are becoming very popular.

White Diamonds

Natural color white diamonds are not colorless, but are actually white. This can often cause confusion as the term is used loosely. A pure white diamond has a translucency or even opacity that makes the diamond white. This is often caused by sub-microscopic inclusions. They occasionally exhibit a weak play of color (similar to opals) called opalescence. These are highly prized among conniseurs.

Gray Diamonds

Gray diamonds are often steely in appearance and to an untrained eye may be hard to distinguish from colorless diamonds. When viewed side-by-side the difference is obvious, a gray diamond is darker than a colorless one. Pure gray diamonds are rare and are frequently described as a masculine color diamond.

Reference:
Wikipedia: Diamond
Wikipedia: Diamond color
Natural Color Diamond Industry Association

Probing giant planets’ dark hydrogen

Probing giant planets-GeologyPage
An illustration of the layer of dark hydrogen the team’s lab mimicry indicates would be found beneath the surface of gas giant planets like Jupiter, courtesy of Stewart McWilliams. Credit: University of Edinburgh (graphics) and NASA (photos)

Hydrogen is the most-abundant element in the universe. It’s also the simplest–sporting only a single electron in each atom. But that simplicity is deceptive, because there is still so much we have to learn about hydrogen.

One of the biggest unknowns is its transformation under the extreme pressures and temperatures found in the interiors of giant planets, where it is squeezed until it becomes liquid metal, capable of conducting electricity. New work published in Physical Review Letters by Carnegie’s Alexander Goncharov and University of Edinburgh’s Stewart McWilliams measures the conditions under which hydrogen undergoes this transition in the lab and finds an intermediate state between gas and metal, which they’re calling “dark hydrogen.”

On the surface of giant planets like Jupiter, hydrogen is a gas. But between this gaseous surface and the liquid metal hydrogen in the planet’s core lies a layer of dark hydrogen, according to findings gleaned from the team’s lab mimicry.

Using a laser-heated diamond anvil cell to create the conditions likely to be found in gas giant planetary interiors, the team probed the physics of hydrogen under a range of pressures from 10,000 to 1.5 million times normal atmospheric pressure and up to 10,000 degrees Fahrenheit.

They discovered this unexpected intermediate phase, which does not reflect or transmit visible light, but does transmit infrared radiation, or heat.

“This observation would explain how heat can easily escape from gas giant planets like Saturn,” explained Goncharov.

They also found that this intermediate dark hydrogen is somewhat metallic, meaning it can conduct an electric current, albeit poorly. This means that it could play a role in the process by which churning metallic hydrogen in gas giant planetary cores produces a magnetic field around these bodies, in the same way that the motion of liquid iron in Earth’s core created and sustains our own magnetic field.

“This dark hydrogen layer was unexpected and inconsistent with what modeling research had led us to believe about the change from hydrogen gas to metallic hydrogen inside of celestial objects,” Goncharov added.

Reference:
R. Stewart McWilliams, D. Allen Dalton, Mohammad F. Mahmood, Alexander F. Goncharov. Optical Properties of Fluid Hydrogen at the Transition to a Conducting State. Physical Review Letters, 2016; 116 (25) DOI: 10.1103/PhysRevLett.116.255501

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

Oldest rocks in Australia unlock secrets of the atmosphere

Oldest rocks in Australia-GeologyPage
The micrometeorites we extracted travelled through the atmosphere about 2.7 billion years ago ago. Credit: iStock

Research into micro-meteorites, meteorites smaller than 2 millimeters, found in Western Australia have shed new light on the make-up of the ancient Earth’s atmosphere.

The Pilbara region in the north of Western Australia has the oldest rocks in Australia, and some of the oldest in the world. Most have barely changed since they were deposited as sediments billions of years ago which allows researchers to unlock secrets of the atmosphere.

“The micrometeorites we extracted travelled through the atmosphere about 2.7 billion years ago. That period is called the Archean Era,” says Monash University’s Dr Andrew Tomkins.

“Imagine an impact between two asteroids in space. Most meteorites have metal particles in them, so when two asteroids collide, lots of fragments come off, and you end up with cosmic dust.

When that dust enters the Earth’s atmosphere, researchers estimate it is moving at more than 12 kilometers a second. Because it’s moving so fast, the fragments can also reach temperatures of more than 1500 degrees.

“As the micrometeorite is traveling at great speed and high temperature, it comes into contact with the Earth’s atmosphere which causes it to slow down and cool off.” Prof Tomkins says.

“When these micrometeorites land on Earth, that information is stored. If that micrometeorite lands in a lake, it can get buried in sediments and becomes preserved in rock”.

Dr Tomkins says his research investigated the interactions between the micrometeorites and the upper atmosphere to reveal how the ancient atmosphere differed from today.

“We targeted a type of sedimentary rock, called limestone, because it is easily dissolved to reveal the micrometeorites,” he says.

“Those particular micrometeorites had been bits of metal floating around in space.”

As the micrometeorites reacted with the oxygen and iron in the atmosphere, it turned from iron mostly, to iron-oxide.

“That told us that there had to be a certain level of oxygen available to do that,” Prof Tompkin says.

Imperial College researcher Dr Matthew Genge performed calculations that showed oxygen concentrations in the upper atmosphere would need to be close to modern day levels to explain the observations.

“What we had done was found a way to show that there was more oxygen than previously expected, and less carbon monoxide,” Dr Tomkins says.

“The findings show the upper atmosphere was oxygen-rich, whilst still allowing the possibility that the lower atmosphere was oxygen-poor. It is basically the first time anybody has been able to figure out a way to look at the chemistry of the upper atmosphere billions of years ago.”

Note: The above post is reprinted from materials provided by Science Network WA.

Super-slow circulation allowed world’s oceans to store huge amounts of carbon during last ice age

Super-slow circulation allowed-GeologyPage
Foraminifera “Star sand” Hatoma Island – Japan Credit: Psammophile

The way the ocean transported heat, nutrients and carbon dioxide at the peak of the last ice age, about 20,000 years ago, is significantly different than what has previously been suggested, according to two new studies. The findings suggest that the colder ocean circulated at a very slow rate, which enabled it to store much more carbon for much longer than the modern ocean.

Using the information contained within the shells of tiny animals known as foraminifera, the researchers, led by the University of Cambridge, looked at the characteristics of the seawater in the Atlantic Ocean during the last ice age, including its ability to store carbon. Since atmospheric CO2 levels during the period were about a third lower than those of the pre-industrial atmosphere, the researchers were attempting to find if the extra carbon not present in the atmosphere was stored in the deep ocean instead.

They found that the deep ocean circulated at a much slower rate at the peak of the last ice age than had previously been suggested, which is one of the reasons why it was able to store much more carbon for much longer periods. That carbon was accumulated as organisms from the surface ocean died and sank into the deep ocean where their bodies dissolved, releasing carbon that was in effect ‘trapped’ there for thousands of years. Their results are reported in two separate papers in Nature Communications.

The ability to reconstruct past climate change is an important part of understanding why the climate of today behaves the way it does. It also helps to predict how the planet might respond to changes made by humans, such as the continuing emission of large quantities of CO2 into the atmosphere.

The world’s oceans work like a giant conveyer belt, transporting heat, nutrients and gases around the globe. In today’s oceans, warmer waters travel northwards along currents such as the Gulf Stream from the equatorial regions towards the pole, becoming saltier, colder and denser as they go, causing them to sink to the bottom. These deep waters flow into the ocean basins, eventually ending up in the Southern Ocean or the North Pacific Ocean. A complete loop can take as long as 1000 years.

“During the period we’re looking at, large amounts of carbon were likely transported from the surface ocean to the deep ocean by organisms as they died, sunk and dissolved,” said Emma Freeman, the lead author of one of the papers. “This process released the carbon the organisms contained into the deep ocean waters, where it was trapped for thousands of years, due to the very slow circulation.”

Freeman and her co-authors used radiocarbon dating, a technique that is more commonly used by archaeologists, in order to determine how old the water was in different parts of the ocean. Using the radiocarbon information from tiny shells of foraminifera, they found that carbon was stored in the slowly-circulating deep ocean.

In a separate study led by Jake Howe, also from Cambridge’s Department of Earth Sciences, researchers studied the neodymium isotopes contained in the foraminifera shells, a method which works like a dye tracer, and came to a similar conclusion about the amount of carbon the ocean was able to store.

“We found that during the peak of the last ice age, the deep Atlantic Ocean was filled not just with southern-sourced waters as previously thought, but with northern-sourced waters as well,” said Howe.

What was previously interpreted to be a layer of southern-sourced water in the deep Atlantic during the last ice age was in fact shown to be a mixture of slowly circulating northern- and southern-sourced waters with a large amount of carbon stored in it.

“Our research looks at a time when the world was much colder than it is now, but it’s still important for understanding the effects of changing ocean circulation,” said Freeman. “We need to understand the dynamics of the ocean in order to know how it can be affected by a changing climate.”

Reference:

  1. Jacob Howe et al. ‘North Atlantic Deep Water Production during the Last Glacial Maximum.’ Nature Communications (2016): DOI: 10.1038/ncomms11765
  2. Emma Freeman et al. ‘Radiocarbon evidence for enhanced respired carbon storage in the Atlantic at the Last Glacial Maximum.’ Nature Communications (2016). DOI: 10.1038/ncomms11998

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

Ancient ‘Deep Skull’ from Borneo full of surprises

Ancient Deep Skull-GeologyPage
Bones from the 37,000 year old Deep Skull from Niah Cave in Sarawak. Credit: Curnoe

A new study of the 37,000-year old remains of the “Deep Skull” – the oldest modern human discovered in island South-East Asia – has revealed this ancient person was not related to Indigenous Australians, as had been originally thought.

The Deep Skull was also likely to have been an older woman, rather than a teenage boy.

The research, led by UNSW Australia Associate Professor Darren Curnoe, represents the most detailed investigation of the ancient cranium specimen since it was found in Niah Cave in Sarawak in 1958.

“Our analysis overturns long-held views about the early history of this region,” says Associate Professor Curnoe, Director of the UNSW Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA).

“We’ve found that these very ancient remains most closely resemble some of the Indigenous people of Borneo today, with their delicately built features and small body size, rather than Indigenous people from Australia.”

The study, by Curnoe and researchers from the Sarawak Museum Department and Griffith University, is published in the journal Frontiers in Ecology and Evolution.

The Deep Skull was discovered by Tom Harrisson of the Sarawak Museum during excavations at the West Mouth of the great Niah Cave complex and was analysed by prominent British anthropologist Don Brothwell.

In 1960, Brothwell concluded the Deep Skull belonged to an adolescent male and represented a population of early modern humans closely related, or even ancestral, to Indigenous Australians, particularly Tasmanians.

“Brothwell’s ideas have been highly influential and stood largely untested, so we wanted to see whether they might be correct after almost six decades,” says Curnoe.

“Our study challenges many of these old ideas. It shows the Deep Skull is from a middle-aged female rather than a teenage boy, and has few similarities to Indigenous Australians. Instead, it more closely resembles people today from more northerly parts of South-East Asia.”

Ipoi Datan, Director of the Sarawak Museum Department says: “It is exciting to think that after almost 60 years there’s still a lot to learn from the Deep Skull – so many secrets still to be revealed.

“Our discovery that the remains might well be the ancestors of Indigenous Bornean people is a game changer for the prehistory of South-East Asia.”

The Deep Skull has also been a key fossil in the development of the so-called “two-layer” hypothesis in which South-East Asia is thought to have been initially settled by people related to Indigenous Australians and New Guineans, who were then replaced by farmers from southern China a few thousand years ago.

The new study challenges this view by showing that – in Borneo at least – the earliest people to inhabit the island were much more like Indigenous people living there today rather than Indigenous Australians, and suggests long continuity through time.

It also suggests that at least some of the Indigenous people of Borneo were not replaced by migrating farmers, but instead adopted the new farming culture when it arrived around 3,000 years ago.

“Our work, coupled with recent genetic studies of people across South-East Asia, presents a serious challenge to the two-layer scenario for Borneo and islands further to the north,” says Curnoe.

“We need to rethink our ideas about the region’s prehistory, which was far more complicated than we’ve appreciated until now.”

Note: The above post is reprinted from materials provided by University of New South Wales.

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