Παρασκευή 21 Μαρτίου 2014
Τρίτη 18 Μαρτίου 2014
When tectonics killed everything
When tectonics killed everything
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| Geostationary Operational Environmental Satellite-11 (GEOS-11) image of the Earth acquired on June 14, 2000. Credit: NOAA |
It's often known as "The Great Dying."
About 252 million years ago, all life nearly vanished. More than 90 percent of ocean species and 70 percent of land species died. Trees, plants, reptiles, fish, insects, microbes—all nearly wiped out.
Scientists have unearthed many clues over the last decades, but they've yet to reach a final verdict. So far the evidence has pointed toward drastic changes on Earth and in the oceans. Oxygen levels were low in the oceans, making it difficult for many animals to survive. Carbon dioxide and methane levels were unusually high, contributing to major warming of the planet. Acid rain fell, and made sea water so acidic that all coral reefs disappeared. The inland turned into an dry desert, hot and arid, and devastated by major wild fires. The climate also varied between periods of sudden warming and cooling, making it impossible for many species to adjust.
Many of these changes have been tied to the eruption of two major volcanoes—one in southern China 260 million years ago, and one in northern Russia 251 million years ago. These would have released the large amounts of carbon dioxide, leading to greenhouse effects and global warming. The carbon dioxide also made the seawater acidic, killing off many marine organisms. The eruptions would also have led to the catastrophic release of methane, another potent greenhouse gas, stored as methane "ice" nearby under the seabed.
But the drama may have already started earlier, some scientists think. Drastic drops in sea levels had already perturbed ocean currents and wind patterns, inducing climate change.
And yet, all these clues could in fact be related.
When All the World Was One
In a paper published this month in Science China, Earth Sciences, two scientists attempt to pull the curtain further back, to give a fuller picture. According to Dr. Yin Hongfu and Dr. Song Haijun of China University of Geosciences (Wuhan), all the events described above may have been set in motion 50 million years before the climax of the catastrophe.
According to the paper, here's how the story may have begun.
According to the paper, here's how the story may have begun.
Some 300 million years ago, at the beginning of the Permian period, all the world's lands had joined into a single supercontinent, Pangea, and all the world's sea water had formed a global ocean, Panthalassa.
The formation of Pangea led to higher mountains and deeper oceans. According to an equilibrium principle, a giant continent should have a thicker crust than each scattered continent, and the oceans should become deeper. This recession of water away from the land would have eliminated a lot of the biodiversity that thrives in shallow water near the coasts. This recession would have also led to changes in ocean currents and wind patterns, initiating global climate changes.
What's more, the inland region of one giant continent would become dry and arid, leading to the disappearance of much vegetation.
But something else also went on, deep within the Earth.
When the lands joined, some tectonic plates moved under others and sunk deep into the Earth's mantle. That cooler material then may have reached all the way to the Earth's core layer. Evidence for that includes the reversal of Earth's magnetic field that occurred around that time, an event called the Illawarra magnetic reversal.
The accumulation of cool material near Earth's core then could have led to the formation of a large mantle plume (by a process called thermo-convection), other researchers had suggested. That "super-plume" would eventually reach the Earth's surface in two separate bursts—first with an eruption in China 260 million years ago, and then with the other in Russia 251 million years ago.
By that point, all life had nearly vanished.
In short, the paper argues that the Great Dying may have been an ongoing process tied to the formation of Pangea, which led to sea level change and climate change, but also and ultimately to what went on inside the Earth.
The formation of Pangea led to higher mountains and deeper oceans. According to an equilibrium principle, a giant continent should have a thicker crust than each scattered continent, and the oceans should become deeper. This recession of water away from the land would have eliminated a lot of the biodiversity that thrives in shallow water near the coasts. This recession would have also led to changes in ocean currents and wind patterns, initiating global climate changes.
What's more, the inland region of one giant continent would become dry and arid, leading to the disappearance of much vegetation.
But something else also went on, deep within the Earth.
When the lands joined, some tectonic plates moved under others and sunk deep into the Earth's mantle. That cooler material then may have reached all the way to the Earth's core layer. Evidence for that includes the reversal of Earth's magnetic field that occurred around that time, an event called the Illawarra magnetic reversal.
The accumulation of cool material near Earth's core then could have led to the formation of a large mantle plume (by a process called thermo-convection), other researchers had suggested. That "super-plume" would eventually reach the Earth's surface in two separate bursts—first with an eruption in China 260 million years ago, and then with the other in Russia 251 million years ago.
By that point, all life had nearly vanished.
In short, the paper argues that the Great Dying may have been an ongoing process tied to the formation of Pangea, which led to sea level change and climate change, but also and ultimately to what went on inside the Earth.
Problems with Pangea
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| Late Permian (260 million years ago) -- All the world's lands had joined into a single supercontinent, Pangea, and all the world's sea water had formed a global ocean, Panthalassa. Credit: Ron Blakey, NAU Geology |
However, many scientists disagree with the theory that the formation of Pangea played any role in the extinction. Some argue that the formation of Pangaea happened too early, and that the dying happened too rapidly, for the two events to be linked.
Others don't think that sea level changes played a role in the extinction. "I don't agree with all the links they propose," says Paul Wignall, a Professor of Palaeoenvironments at the University of Leeds. "The peak regression [low sea levels] in the late Permian is significantly before the mass extinction and so unlikely to be a factor."
As for the other factors, most scientists seem to have reached a consensus. "The paper is not really saying anything new but giving an overview of the key factors responsible," Wignall adds. "Nearly all, including me, blame volcanism."
But the paper's real point, it seems, is that both the formation of Pangea and the volcanic eruptions were caused by processes deep inside the Earth—which could have been related, even if one occurred before the other.
The links between inner Earth, Earth's surface, and the evolution of life is "an important theme of the earth system science that is worthy of further investigation," wrote the authors.
But they also concede that their hypothesis is just that, an hypothesis, and that more research is needed. They end the paper, perhaps fittingly, with a quote by an ancient Chinese poet named Qu Yuan, who wrote:
"Long as might be the road, keep searching above and below I would."
Others don't think that sea level changes played a role in the extinction. "I don't agree with all the links they propose," says Paul Wignall, a Professor of Palaeoenvironments at the University of Leeds. "The peak regression [low sea levels] in the late Permian is significantly before the mass extinction and so unlikely to be a factor."
As for the other factors, most scientists seem to have reached a consensus. "The paper is not really saying anything new but giving an overview of the key factors responsible," Wignall adds. "Nearly all, including me, blame volcanism."
But the paper's real point, it seems, is that both the formation of Pangea and the volcanic eruptions were caused by processes deep inside the Earth—which could have been related, even if one occurred before the other.
The links between inner Earth, Earth's surface, and the evolution of life is "an important theme of the earth system science that is worthy of further investigation," wrote the authors.
But they also concede that their hypothesis is just that, an hypothesis, and that more research is needed. They end the paper, perhaps fittingly, with a quote by an ancient Chinese poet named Qu Yuan, who wrote:
"Long as might be the road, keep searching above and below I would."
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| The iron in Earth's inner core weakens dramatically before it melts, explaining the unusual properties that exist in the moon-sized solid center of our planet that have, up until now, been difficult to understand. (Credit: iStockphoto) |
Scientists use seismic waves -- pulses of energy generated during earthquakes -- to measure what is happening in the Earth's inner core, which at 6000 km beneath our feet is completely inaccessible.
Problematically for researchers, the results of seismic measurements consistently show that these waves move through the Earth's solid inner core at much slower speeds than predicted by experiments and simulations.
Now, in a paper published in Science, scientists from UCL have proposed a possible explanation. They suggest that the iron in the Earth's core may weaken dramatically just before melting, becoming much less stiff. The team used quantum mechanical calculations to evaluate the wave velocities of solid iron at inner-core pressure up to melting.
They calculated that at temperatures up to 95% of what is needed to melt iron in the Earth's inner core, the speed of the seismic waves moving through the inner core decreases linearly but, after 95%, it drops dramatically.
At about 99% of the melting temperature of iron, the team's calculated velocities agree with seismic data for the Earth's inner core. Since independent geophysical results suggest that the inner core is likely to be at 99-100% of its melting temperature, the results presented in this paper give a compelling explanation as to why the seismic wave velocities are lower than those predicted previously.
Professor Lidunka Vočadlo, from the UCL department of Earth Sciences and an author of the paper said: "The Earth's deep interior still holds many mysteries that scientists are trying to unravel.
"The proposed mineral models for the inner core have always shown a faster wave speed than that observed in seismic data. This mismatch has given rise to several complex theories about the state and evolution of the Earth's core."
The authors stress that this is not the end of the story as other factors need to be taken into account before a definitive core model can be made. As well as iron, the core contains nickel and light elements, such as silicon and sulphur.
Professor Vočadlo said: "The strong pre-melting effects in iron shown in our paper are an exciting new development in understanding the Earth's inner core. We are currently working on how this result is affected by the presence of other elements, and we may soon be in a position to produce a simple model for the inner core that is consistent with seismic and other geophysical measurements. "
Παρασκευή 14 Μαρτίου 2014
Raw: Baby Gorilla Born in Rare C-section
An infant gorilla was been delivered by a rare animal Caesarean-section at the San Diego Zoo Safari Park on Wednesday. (March 14)
Πέμπτη 13 Μαρτίου 2014
Rare Diamond Reveals Earth's Interior is All Wet
Rare Diamond Reveals Earth's Interior is All Wet
By Becky Oskin, Senior Writer | March 13, 2014 01:52am ET
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 A diamond from Juína, Brazil, containing a water-rich inclusion of the olivine mineral ringwoodite.Credit: Richard Siemens/University of Alberta
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"It's actually the confirmation that there is a very, very large amount of water that's trapped in a really distinct layer in the deep Earth," said Graham Pearson, lead study author and a geochemist at the University of Alberta in Canada. The findings were published today (March 12) in the journal Nature.
The worthless-looking diamond encloses a tiny piece of an olivine mineral called ringwoodite, and it's the first time the mineral has been found on Earth's surface in anything other than meteorites or laboratories. Ringwoodite only forms under extreme pressure, such as the crushing load about 320 miles (515 kilometers) deep in the mantle.
What's in the mantle?
Most of Earth's volume is mantle, the hot rock layer between the crust and the core. Too deep to drill, the mantle's composition is a mystery leavened by two clues: meteorites, and hunks of rock heaved up by volcanoes. First, scientists think the composition of the Earth's mantle is similar to that ofmeteorites called chondrites, which are chiefly made of olivine. Second, lava belched by volcanoes sometimes taps the mantle, bringing up chunks of odd minerals that hint at the intense heat and pressure olivine endures in the bowels of the Earth.
In recent decades, researchers have also recreated mantle settings in laboratories, zapping olivine with lasers, shooting minerals with massive guns and squeezing rocks between diamond anvils to mimic the Earth's interior.
These laboratory studies suggest that olivine morphs into a variety of forms corresponding to the depth at which it is found. The new forms of crystal accommodate the increasing pressures. Changes in the speed of earthquake waves also support this model. Seismic waves suddenly speed up or slow down at certain depths in the mantle. Researcher think these speed zones arise from olivine's changing configurations. For example, 323 to 410 miles (520 to 660 km) deep, between two sharp speed breaks, olivine is thought to become ringwoodite. But until now, no one had direct evidence that olivine was actually ringwoodite at this depth. [Infographic: What is Earth Made Of?]
"Most people (including me) never expected to see such a sample. Samples from the transition zone and lower mantle are exceedingly rare and are only found in a few, unusual diamonds," Hans Keppler, a geochemist at the University of Bayreuth in Germany, wrote in a commentary also published in Nature today.
Earth's deepest ocean
The diamond from Brazil confirms that the models are correct: Olivine is ringwoodite at this depth, a layer called the mantle transition zone. And it resolves a long-running debate about water in the mantle transition zone. The ringwoodite is 1.5 percent water, present not as a liquid but as hydroxide ions (oxygen and hydrogen molecules bound together). The results suggest there could be a vast store of water in the mantle transition zone, which stretches from 254 to 410 miles (410 to 660 km) deep.
"It translates into a very, very large mass of water, approaching the sort of mass of water that's present in all the world's ocean," Pearson told Live Science's Our Amazing Planet.
Partial cross-section of the Earth showing the location of ringwoodite in the mantle.Credit: Kathy Mather
Keppler noted that it's possible the volcanic eruption that brought the deep diamond to Earth's surface may have sampled an unusually water-rich part of the mantle, and that not all of the transition-zone layer may be as wet as indicated by the ringwoodite.
"If the source of the magma is an unusual mantle reservoir, there is the possibility that, at other places in the transition zone, ringwoodite contains less water than the sample found by Pearson and colleagues," Keppler wrote. "However, in light of this sample, models with anhydrous, or water-poor, transition zones seem rather unlikely."
Ride on a rocket
A violent volcanic eruption called a kimberlite quickly carried this particular diamond from deep in the mantle. "The eruption of a kimberlite is analogous to dropping a Mentos mint into a bottle of soda," Pearson said. "It's a very energetic, gas-charged reaction that blasts its way to Earth's surface."
Graham Pearson holds a diamond that yields new clues about the presence of large amounts of water deep beneath the Earth.Credit: Richard Siemens/University of Alberta
The ringwoodite discovery was accidental, as Pearson and his co-authors were actually searching for a means of dating the diamonds. The researchers think careful sample preparation is the key to finding more ringwoodite, because heating ultradeep diamonds, as happens when scientists polish crystals for analysis, causes the olivine to change shape.
"We think it's possible ringwoodite may have been found by other researchers before, but the way they prepared their samples caused it to change back to a lower-pressure form," Pearson said.
RED BEARD: MERCEDES-BENZ FASHION WEEK ISTANBUL PRESENTED BY AMERICAN EXP...
Runway looks from the RED BEARD Fall/Winter 2014 Collection at Mercedes-Benz Fashion Week Istanbul presented by American Express. The Official Mercedes-Benz Fashion Week Istanbul presented by American Express YouTube channel provides extensive coverage of runway shows including ARZU KAPROL, ECE GÖZEN, DB BERDAN, JANUCHA BY JALE HÜRDOĞAN, BURÇE BEKREK, ZEYNEP TOSUN, NİAN. RED BEARD Sonbahar/Kış 2014 Koleksiyonu defilesinden görüntüler. Mercedes-Benz Fashion Week Istanbul presented by American Express YouTube kanalında ARZU KAPROL, ECE GÖZEN, DB BERDAN, JANUCHA BY JALE HÜRDOĞAN, BURÇE BEKREK, ZEYNEP TOSUN, NİAN ve daha birçok defileyi izleyebilirsiniz.
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Τετάρτη 19 Φεβρουαρίου 2014
Talks between Ukrainian govt, opposition fail as 25 killed in Kiev unrest
US, EU are ‘neck deep’ in plan to see pro-Western regime change in Ukraine
"The United States and NATO and the EU are together using their combined forces to signal to these demonstrators that 'We are with you,'" he said. The EU, NATO leadership and the Obama administration "are neck deep now in a plan to carry out regime change in this extremely important part of Europe, trying to integrate a former Soviet republic into the EU and, of course, into NATO ultimately."Though the Ukrainian conflict is complex, with "its own dynamic," protesters are certainly emboldened by support from Western powers, Brian Becker, director of the anti-war ANSWER Coalition, told RT in an interview.
In the cheerleading for protesters coming from Washington, Becker believes the US is fomenting discontent to further its reach into Russia's backyard.
"I think the United States government is playing another dirty game. They're trying to do what they have tried to do for the last 20 years, which is to incorporate all of the former socialist countries in the eastern and central European bloc - those that were aligned with the Soviet Union - into an American-Western-NATO sphere of influence," he said.
RT: Some are saying that extremists among the demonstrators are now emboldened to be violent after such strong support from abroad. Are the EU and the US really to blame for this?
Brian Becker: I think there's an inter-tangling here, of course. The internal struggle within Ukraine is complex, it is complicated, it has its own dynamic. And there is a very far-right fascist and semi-fascist force that is opting for violence and really armed struggle to overthrow the government, as a tactic to integrate Ukraine into the EU and into the Western powers. But behind that, the wind in their sails right now - and we can see it from the upsurge of violence - does come from the most important military powers in the Western world: the United States and NATO and the EU together are using their combined forces to signal to these demonstrators that 'We are with you.' And of course that emboldens them. [US Secretary of State] John Kerry and the EU, NATO leadership, and the Obama administration are neck deep now in a plan to carry out regime change in this extremely important part of Europe, trying to integrate a former Soviet republic into the EU and, of course, into NATO ultimately.
RT: But Brussels and Washington don't want to see people dying over this, do they?
BB: I think the United States government is involved in invasion after invasion, occupation of countries, bombing of countries. I don't know if the loss of human life is really the ultimate criteria. I really don't believe so. I think the United States government is playing another dirty game. They're trying to do what they've been doing for the last 20 years, which is to incorporate all of the former socialist countries in the eastern and central European bloc - those that were aligned with the Soviet Union - into an American-Western-NATO sphere of influence. And Ukraine is a big prize, with a very big military and it is right on Russia's border. It's part of a new Cold War against Russia, as well.
RT: There's even been talk of sanctions against Kiev. Why do Western officials insist on blaming the government for the violence?
BB: Can you imagine in the United States - where police forces arrested 7,000 people in the Occupy movement, which was a completely peaceful movement that [the US] broke because they feared any rising discontent against inequality - they're now telling this sovereign government of Ukraine, confronted with armed mobs and people carrying Molotov cocktails and guns, that if they use police force, that it is a violation of [protesters'] right of dissent. The hypocrisy here is dripping. I mean, the United States government has no right - when they foment opposition, arm opposition groups from Syria to Libya, and now in Ukraine - and then say when a government responds to it, 'See, you're violating people's constitutional rights or free speech rights.' That's just a propaganda game.
RT: Is there really a serious riff forming between Russia and the EU about this?
BB: The EU triggered this whole protest movement. They signaled their pro-European forces inside Ukraine when they gave an ultimatum to the Ukrainian government back in November. 'Which side are you on? Are you going to maintain your economic and political and diplomatic ties with Russia, or are you going to come into the EU?' And under the condition of that ultimatum, these protests began and great pressure was brought to bear on the Ukrainian government. This is a destabilization campaign. It's a coordinated economic, political, and ultimately military destabilization campaign against an important country, a country that's historically linked first to the Soviet Union and to Russia. They want to bring it over into the camp of the American government, which has expansionist designs. They want to encircle Russia in order to conquer what was formally an independent part of the world. And subjugate it, dominate it, and of course the Russians perceive it as a threat. This was an EU-provoked crisis, not a Russian-provoked crisis.
RT: What about people in Ukraine who do want to see a change in the government? They're fed up with corruption and a poor standard of living.
BB: Indeed, there are many different forces that are struggling against the Yanukovich government. There are some to the right, some to the left. It's very complex. Many have legitimate grievances. There's high unemployment. The breakup of the Soviet Union led to an evisceration of the people in Ukraine. That's not the issue, though, for the United States and the EU countries, which are using valid grievances against the Ukrainian government for a larger, geostrategic purpose, which is to integrate Ukraine into the Western bloc.
RT: Ukraine is divided by east and west, loyalties to Russia and the EU. Are we seeing a country split in half?
BB: Yes, there's eastern Ukraine with historic ties to Russia, and the west is more oriented towards the EU. But there's also a class divide; there's rich and poor. And of course the upper classes, those who have been courted by Western powers, are being told, 'Look, if you come with us, you will become very, very rich.' They have nothing in common with the Ukrainians, who are poor and who have been suffering for the last 20 years. There's a class divide in addition to a geographic divide.
RT: There's talk of a civil war. If so, should there be a neutral moderator? Who would it be?
BB: What needs to happen is the EU countries and, I would say as an American, we have to tell our government, 'stop trying to foment civil disruption Ukraine,’ maybe possibly fomenting civil war as they did in the case of Syria, for instance, or Libya. 'Stop doing that.' The Ukrainian people, and only they, should be the determiners of their destiny. They should have real self-determination, which means the Western powers need to get out and leave them alone.
Making public appeals to arm the opposition has crossed the line, declared Ukrainian President Viktor Yanukovich in address to the nation published on his website.
“This is a glaring violation of the law. The offenders must appear before a tribunal which will determine the measure of punishment for them. This is not my caprice, it is my duty as a guarantor of the Constitution - to ensure peace in the country, the peace of the citizens and justice for everyone,”the statement says.
The leaders of the opposition should immediately dissociate from the radicals provoking bloodshed and clashes with law enforcement, demanded Yanukovich.
“If they do not wish to abide, they ought to declare that they support the radicals. In that case they would be treated respectively,” the president declared.
Viktor Yanukovich said that opposition leaders demanded full power without elections, which is unconstitutional.
“I told the [opposition leaders] many times – elections are close. If people trust you, you will be in power. If they do not, you won’t. But both must occur legally, according to the Constitution of Ukraine,” Yanukovich stated.
During a phone call to Viktor Yanukovich, US Vice-President Joe Biden expressed “grave concern”at the surge of violence in the Ukrainian capital. Biden urged Yanukovich to exercise maximum restraint and pull back law enforcement confronting the rioters in downtown Kiev.
With the White House condemning violence in Ukraine, Biden maintained it is the special responsibility of Ukraine's government to defuse tension.
The Ukrainian Interior Ministry reported that seven police officers died of gunshot wounds during the clashes. Two additional officers were later killed and another was critically injured as a traffic police unit was attacked in Kiev. The police officers died while in pursuit of the offenders.
The ministry added that 135 law enforcers have been taken to nearby hospitals, 35 of whom are in critical condition.
Kiev’s hospitals are unable to handle the large amount of injured people coming in from the streets, TSN reported. There is a wait for operation rooms and people are being carried in with various types of injuries. There have been reports of two amputations, punched out eyes, and injured extremities.
Thousands continue to occupy Kiev's Independence Square as state security forces move in to disperse the crowds.
Fighting in the Independence Square (Maidan) area has intensified, according to Twitter reports. Riot police are reportedly on the offensive, throwing stun grenades and spraying tear gas. Rioters are responding with Molotov cocktails. Gunshots can be heard.
Another group of around 1,000 rioters attempted to storm a district police headquarters building in Kiev, using an explosive device in the process. The rioters seized two trolley buses in order to block streets and a truck which they used to ram police cordons. They also smashed an ambulance and broke into several offices in central Kiev.
As the situation in Kiev intensifies, violence has been spreading to the west of the country. Hundreds of young rioters in the western city of Lvov seized the regional administration building and stormed the Lvov Central Internal Affairs Directorate, Interfax reported.
Rioters have also seized a military base, Ukrainian news website UA-RU.info reported. The protesters agreed with the military that troops would leave the base without weapons, and weapons warehouses have been sealed. A fire has engulfed the barracks. Thirty soldiers have been injured, five of whom were hospitalized, following the attack on the military unit, according to local police.
Around 300 rioters have also surrounded the local administration building and police department in the western city of Ternopol, Unian reported. Protesters threw bricks at the police department's windows and demanded that officers evacuate the building. As policemen began making their way out through the back exit, rioters continued to throw rocks and chased them down the street. There are reports that three smoke bombs and grenades were used.
Meanwhile, the southern Ukrainian Autonomous Republic of Crimea has urged President Viktor Yanukovich to come up with “decisive action and emergency measures” to end riots and restore constitutional order.
“The peaceful Crimea is extremely concerned with the latest surge of violence in central Kiev. The carnage on the capital’s streets proves that the opposition has taken manifold concessions on part of the government for a show of its weakness, and has used the amnesty law as a break before a new attempt of a forceful power grab,” Crimea’s Supreme Council said in a Tuesday statement.
According to the statement, the general mobilization – called by “extremist” groups like the Right Sector and the Svoboda Party – is nothing but the start of a civil war in Ukraine.
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