Archive for the ‘Geosciences’ Category

India was not completely isolated as it moved from Gondwanaland to Asia

January 15, 2017

India – from Gondwanaland to Asia (after Wikipedia)

About 135 million years ago India and Mandagascar broke away from Gondwanaland and started shifting North North East. Around 88 million years ago, India and Madagascar split and the movement of the Indian tectonic plate speeded up. It crashed into Asia from about 30 million years ago to around 10 million years ago (though the movement still continues today). It had been thought that India was biologically isolated from about 71 million years ago until about 30 million years ago when some species hopping occurred from Africa and Asia.

This period was also extraordinarily rich in the evolutionary history of the mammals. It was the time when snakes and ants first appeared. There was a mass extinction event about 66 million years ago. The dinosaurs disappeared and became birds. Birds proliferated and so did large flightless birds. The diversity of mammals exploded, perhaps just because of the space left by the disappearance of the large, unsuccessful dinosaurs. The first pigs and deer developed. The grasses arrived. Carnivorous mammals appeared as their prey increased. The first primates made an entrance. But whatever was evolving on the Indian land-mass was evolving largely in isolation from that taking place in the areas that were to become Africa and Eurasia. But there are tantalising indications that on its journey the Indian land-mass may have been connected for short periods by a land bridge to the Horn of Africa or to what is now Arabia.

However a new paper suggests that some biological movement – perhaps across island chains – was taking place as early as 54 million years ago.

Frauke Stebner, Ryszard Szadziewski, Hukam Singh, Simon Gunkel, Jes Rust. Biting Midges (Diptera: Ceratopogonidae) from Cambay Amber Indicate that the Eocene Fauna of the Indian Subcontinent Was Not Isolated. PLOS ONE, 2017; 12 (1): e0169144 DOI: 10.1371/journal.pone.0169144

Bonn University Press Release: 

India gradually drifted away from Africa and Madagascar towards the north and collided with the Eurasian plate. Scientists assumed for a long time that the subcontinent was largely isolated during its long journey through the ocean and unique species of plants and animals were therefore able to develop on it. However, paleontologists at the University of Bonn are now showing using tiny midges encased in amber that there must have been a connection between the apparently cut off India and Europe and Asia around 54 million years ago that enabled the creatures to move around. The surprising results are now presented in the journal PLOS ONE.

India harbours many unique species of flora and fauna that only occur in this form on the subcontinent. The prerequisite for such a unique development of species is that no exchange takes place with other regions. For a long time, scientists assumed that India was isolated in this way due to continental drift. The supercontinent Gondwana, which included South America, Africa, Antarctica, Australia, Madagascar and India, broke up over the course of geological history. What is now India also began moving towards the north east around 130 million years ago. It was common belief among researchers that, before it collided with the Eurasian plate, India was largely isolated for at least 30 million years during its migration.

However, according to current findings by paleontologists at the University of Bonn, the Indian subcontinent may not have been as isolated on its journey as we have thought. “Certain midges that occurred in India at this time display great similarity to examples of a similar age from Europe and Asia,” says lead author Frauke Stebner from the working group of Prof. Jes Rust at the Steinmann Institute at the University of Bonn. These findings are a strong indicator that an exchange did occur between the supposedly isolated India, Europe and Asia.

Mining for amber in the Indian coal seams

The scientist from the University of Bonn mined for amber in seams of coal near the Indian city of Surat. Small midges, among other things, were encased in tree resin 54 million years ago and preserved as fossils. The tiny insects, which are often not even a millimeter large, are “biting midges”. Their descendants can still be found today in Germany in meadows and forests – where the little beasts attack you in swarms and suck your blood.

The paleontologist investigated a total of 38 biting midges encased in amber and compared them with examples of a similar age from Europe and China. Scientists from the University of Gdańsk (Poland) and Lucknow (India) were also involved in this. It has been possible to assign a total of 34 of these insect fossils to genera that are already known. “There was significant conformity with biting midges in amber from the Baltic and Fushun in north-east China,” reports Stebner.

Chains of islands presumably created a link to India

How the insects were able to spread between drifting India and Eurasia has not yet been clarified fully. “Nevertheless, it also seems to have been possible for birds and various groups of mammals to cross the ocean between Europe and India at the time,” the paleontologist refers to studies by other scientists. However, it has now been possible for the first time, with the aid of biting midge fossils, to also demonstrate an exchange between India and Asia in this period.

Stebner assumes that a chain of islands that existed at that time between India, Europe and Asia could have helped the biting midges to spread. As if from stepping stone to stepping stone, the insects could have gradually moved forward along the islands. “Some of the biting midges found in Indian amber were presumably not especially good long-distance flyers,” smiles the paleontologist from the University of Bonn. It was therefore probably not so easy to reach the subcontinent or move from there during the migration of India.

Right click to download: Gedanohelea gerdesorum in 54 million-year-old Cambay amber from India:

Gedanohelea gerdesorum in 54 million-year-old Cambay amber from India: (c) Photo: Working group Prof. Ryszard Szadziewski/University of Gdańsk (Poland)


 

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Nostradamus had nothing to say about 2016, but a VEI 5+ volcano eruption is very probable

December 31, 2015

Apart from for 1999, which is specifically mentioned in one of Nostradamus’ quatrains, there is nothing he had to say which can be specifically attributed to 2016. Moreover, not only did the King of Terror he foresaw for the seventh month of 1999 not appear, but there was no event at that time which came anywhere near to his prediction.

So the coming of WW III or of the next anti-Christ or a new invasion of Europe from the Asian steppes in 2016, as many of the Nostradamus brigade are now predicting, are not actually with any foundation. And even if they were, Nostradamus interpretations have a remarkably poor record in forecasts (but a very good record for hindcasts).

Quatrain X-72:

The year 1999, seventh month,

From the sky will come a great King of Terror:

To bring back to life the great King of the Mongols,

Before and after Mars to reign by good luck.

Depending upon calendar, the seventh month refers to July or September. During that period NATO was conducting a local air-war in Serbia and the Russians were battling rebels in Chechnya. But there was little else to match a King of Terror or a new King of the Mongols.

But I do see a high probability of a natural catastrophe during 2016.

The last 25 years have been a remarkably quiet time for major volcanic eruptions. But 2016 may well see a major VEI 5+ volcano eruption, which is now very long overdue. The Puyehue-Cordón Caulle eruption of 2012 is sometimes stated to be of strength VEI 5, but it seems more likely it was no more than a VEI 4. The last VEI 5+ eruptions were in 1991 (Mt. Pinatubo and Mt. Hudson) and that is 25 years ago. Through the 20th century, VEI 5+ eruptions occurred on an average every 7 years (max gap 23 years) and every 11 years during the 19th century. So for 2016, there is a high probability of a major volcanic eruption. Of course, the Ring of Fire is where this is most likely to occur. But my hunch is that the next major eruption could be in the Northern hemisphere. In which case the Mediterranean or Iceland come into the picture.

Ring of Fire image from http://volcanoespaster.weebly.com/

Ring of Fire image from volcanoespaster.weebly.com

I note in passing that the earth’s magnetic field continues to weaken and the poles continue to drift. It is not inconceivable that another rapid magnetic reversal event such as the Laschamp event is currently underway. Reversal of the geomagnetic field occur regularly, but slowly, over geologic time periods. The Laschamp event however occurred very rapidly with the magnetic North Pole drifting to the Antarctic and back again over some 500 years.

Phys.org: 41,000 years ago, a complete and rapid reversal of the geomagnetic field occured. ……. What is remarkable is the speed of the reversal: “The field geometry of reversed polarity, with field lines pointing into the opposite direction when compared to today’s configuration, lasted for only about 440 years, and it was associated with a field strength that was only one quarter of today’s field,” explains Norbert Nowaczyk. “The actual polarity changes lasted only 250 years. In terms of geological time scales, that is very fast.” During this period, the field was even weaker, with only 5% of today’s field strength. As a consequence, the Earth nearly completely lost its protection shield against hard cosmic rays, leading to a significantly increased radiation exposure.

Two other events of note occurred simultaneously – though that may just be coincidence. Forty thousand years ago is close to the time when the Neanderthals disappeared as a separate species and continued only as those absorbed within modern humans. It was also the time when the supervolcano (VEI 7+) erupted 39400 years ago in the area of today’s Phlegraean Fields (Campi Flegrei) near Naples. It was the largest volcanic eruption on the Northern hemisphere in the past 100 000 years.

The polarity reversal was a global event. © Dr. habil. Norbert R. Nowaczyk / GFZ

The magnetic poles are already a long way away from the geographic poles. The South magnetic pole in particular is already outside the polar circle.

NOAA: The most recent survey determined that the Pole is moving approximately north-northwest at 55 km per year.

Currently, in 2015 the location of the north magnetic pole is 86.27°N and 159.18°W and the south magnetic pole is 64.26°S and 136.59°E.

Pole reversal is not a catastrophic event in itself. Even with a weak magnetic field, the atmosphere provides good protection against radiation and the effects would probably not be catastrophic. But the indirect effects of changing flow patterns in the earth’s core (which might be the cause of geomagnetic reversal), on tectonics, volcanic activity and climate may be much more profound. My gut tells me that that the releases of energy which accompany major earthquakes and volcanic eruptions can only be explained by the flow patterns in the earth’s core which power the movement of the tectonic plates – and also control the earth’s magnetic field.

If last year the probability of a VEI 5+ eruption was said to be 95% over the next 5 years, then the chances of a major eruption in 2016 are now quite high.

Great Himalayan earthquake is still waiting to happen

April 27, 2015

This earthquake in Nepal – devastating as it was – has not released enough of the pent-up strain under the Himalayas. The death toll now exceeds 3,500 and most are due to collapsing buildings.

It would need about 50 such quakes with magnitude 7.9  or one super quake of magnitude 9 to release all the slip built up over centuries. The Indian tectonic plate is being subducted under the Eurasian tectonic plate with the Indian Plate moving North East at about 6 -7 cm per year while the Eurasian Plate is moving Northwards at about 2 cm per year. There is a net 2 – 3 cm of slip to be accumulated – or to be relieved by some form of energy release – every year.

The Great Himalayan Earthquake has still to come. The scale of loss of life and devastation will be magnified greatly if the Great quake is located in the central Himalayas such that the tremors extend into the densely populated Gangetic Plain. The central Himalayas have not seen any large quakes for about 700 years and the pent-up energy is ominous. It is highly unlikely that either in Nepal or in the vulnerable regions of India, that buildings will be sufficiently “earthquake-proofed” to minimise the loss of life (and over 90% of the loss of life is due to the collapse of buildings).

Down to Earth: … It has been hypothesised for long that a large earthquake, called the “great Himalayan earthquake”, can strike anytime, but its time and place cannot be predicted. In many locations in the Himalayan belt there is enough energy stored currently to lead to one.

At a magnitude of 7.9 on the Richter scale, the April 25 earthquake has caused devastation but it is not the anticipated “great Himalayan earthquake”.  This does not qualify as a great earthquake which needs to be of magnitude 8, says Roger Bilham, geologist with the University of Colorado Boulder who studies the seismicity of the Himalayan area. “The earthquake is in a region that is being compressed by18 mm each year,” he says. The amount today’s earthquake slip would have been exactly right to release all this accumulated stress, he adds. His team has identified some areas where the great Himalayan earthquake is anticipated (see image). The question mark shows the area where an earthquake is potentially possible but the magnitude is not known.

himakayan

Anticipated Himalayan Earthquakes

 “This (Nepal earthquake) has unfortunately not come as a surprise. We expected an earthquake of high magnitude in the region between Kathmandu and Pokhara,” says Paul Tapponnier from Nanyang Technological University’s Earth Observatory of Singapore who also studies earthquakes in the area. Tapponnier’s earlier work showed that the quakes in 1255 and 1934 were ground-breaking quakes or when ruptures develop in the earth’s crust and the pent up energy in the earth is released. As the areas west or east of the 1934 Nepal ground rupture do not have records of earthquakes, they are at a greater risk of a major earthquake.

In a paper published just two months ago scientists from the Jawaharlal Nehru Centre for Advanced Scientific Research conclude that “the frontal thrust in central Himalaya may have remained seismically inactive during the last ~700 years. Considering this long elapsed time, a great earthquake may be due in the region”.

The Himalaya has experienced three great earthquakes during the last century—1934 Nepal-Bihar, 1950 Upper Assam, and arguably the 1905 Kangra. Focus here is on the central Himalayan segment between the 1905 and the 1934 ruptures, where previous studies have identified a great earthquake between thirteenth and sixteenth centuries. Historical data suggest damaging earthquakes in A.D. 1255, 1344, 1505, 1803, and 1833, although their sources and magnitudes remain debated. ….. Age data suggest that the last great earthquake in the central Himalaya most likely occurred between A.D. 1259 and 1433. While evidence for this rupture is unmistakable, the stratigraphic clues imply an earlier event, which can most tentatively be placed between A.D. 1050 and 1250. …. Rupture(s) identified in the trench closely correlate with two damaging earthquakes of 1255 and 1344 reported from Nepal. The present study suggests that the frontal thrust in central Himalaya may have remained seismically inactive during the last ~700 years. Considering this long elapsed time, a great earthquake may be due in the region.

Other scientists also estimate that this current quake has dissipated only a very small part of the energy stored under the Himalayas and waiting to be released:

Indian Express:

“We know there is a huge amount of accumulated strain in this area. It is due for a major earthquake, perhaps a series of earthquakes, bigger than 8 on the Richter scale. That is the kind of energy that is estimated to be accumulated there. This was certainly not one of those earthquakes that is probably imminent. In terms of energy release, I would say this would not have released even four or five per cent of the energy that is estimated to be stored there,” said Harsh K Gupta, former director of the Hyderabad-based National Geophysical Research Institute and a former member of the National Disaster Management Authority.

Prof Sankar Kumar Nath of IIT Kharagpur, who has studied seismic activity in the Himalayan region, said the energy released from Saturday’s earthquake “was equivalent to the explosion of about 100mn tonnes of TNT, comparable to the energy in detonation of small nuclear bombs”.

“This earthquake would only be classified as medium in terms of energy released. That area, the 2500-km stretch from the Hindukush region to the end of Arunachal Pradesh, is capable of generating much bigger earthquakes, even nine on Richter scale,” he said.

“If you look at it differently, we are actually lucky that only a 7.9-magnitude earthquake has come. I would be very happy to have a few 7.9-magnitude earthquakes than a 9-magnitude earthquake which would be absolute disaster. The trouble is that in terms of energy release, which is what causes the damage, it would take 40 to 50 earthquakes of magnitude 7.9 to avoid an earthquake of magnitude 9,” he said.

Nepal earthquake toll near 1500 with casualties also in India and Tibet

April 25, 2015

The Indian Tectonic Plate is being subducted under the Eurasian Plate. The collision is still going on with the Indian Plate moving North East at about 6 -7 cm per year while the Eurasian Plate is moving Northwards at about 2 cm per year. The subduction occurs in fits and starts and relies on earthquakes to release the slip pressure. The likelihood of a single Himalayan earthquake of magnitude 8 or a series of magnitude 7 quakes was discussed a few years ago

If a great earthquake has not occurred on a specific segment in the Himalaya for 200 years, that segment will slip 4m because the convergence rate between India and Tibet is roughly 2cm each year. If it has not occurred for 500 years the segment would slip 10m, enough for an event that would measure 8, or Magnitude Eight on the Richter Scale. The time interval between great earthquakes thus determines the amount of slip that will occur in the next one.

…. A large segment of the Himalaya between Kathmandu and Dehradun has a record of several earthquakes but only two large ones: an event in 1803 and another in 1833. If these were great earthquakes then there is now roughly 3m of slip ready to go. However, if they were magnitude 7 earthquakes, then there may be more than 20m of slips availabIe for a future great earthquake.

Nepal earthquake map

graphic: BBC

It would seem that this earthquake near Kathmandu was a large one (7.8 magnitude) and may have released around 5 – 8 m of slip but as has been pointed out there may be a total of around 20m of slip waiting to occur. The current quake has so far seen some 16 aftershocks of magnitude 4.5 or greater. Deaths in India are over 40 and the Indian government is mounting a large rescue effort in support of the Nepali government, “Fifty doctors have arrived from India to provide emergency services. India dispatched as many as four aircraft including a C-130 plane carrying three tonnes of relief supplies and a 40-member rescue team to Nepal.” Three more planes are to follow carrying a mobile hospital and medical supplies.

FirstPost: The quake measuring 7.9 on Richter scale, which was followed by 16 aftershocks of magnitude 4.5 or greater, striking heavy casualties in Kathmandu and injuring thousand others. Hundreds were feared missing across the country. “Army estimates death toll as much as 1457 so far,” Nepal’s Finance Minister Ram Sharan Mahat tweeted. …….

The earthquake around 11:56 am with epicentre at Lamjung, around 80 kilometers northwest of Kathmandu, had its impact in several cities in Bihar, West Bengal and Uttar Pradesh and tremors were felt across vast stretches of east and North East India. It was also felt in Southern and Western parts of India, China, Bhutan and as far as Pakistan and Bangladesh.

The US Geological Survey reports:

The April 25, 2015 M 7.8 Nepal earthquake occurred as the result of thrust faulting on or near the main frontal thrust between the subducting India plate and the overriding Eurasia plate to the north. At the location of this earthquake, approximately 80 km to the northwest of the Nepalese capital of Kathmandu, the India plate is converging with Eurasia at a rate of 45 mm/yr towards the north-northeast, driving the uplift of the Himalayan mountain range. The preliminary location, size and focal mechanism of the April 25 earthquake are consistent with its occurrence on the main subduction thrust interface between the India and Eurasia plates.

Although a major plate boundary with a history of large-to-great sized earthquakes, large earthquakes on the Himalayan thrust are rare in the documented historical era. Just four events of M6 or larger have occurred within 250 km of the April 25, 2015 earthquake over the past century. One, a M 6.9 earthquake in August 1988, 240 km to the southeast of the April 25 event, caused close to 1500 fatalities. The largest, an M 8.0 event known as the 1934 Nepal-Bihar earthquake, occurred in a similar location to the 1988 event. It severely damaged Kathmandu, and is thought to have caused around 10,600 fatalities.

Was this the big earthquake that was predicted in the Himalayas?

In an interview to The Hindu in May 2013, Vinod Kumar Gaur, seismologist with the Centre for Mathematical Modelling and Computer Simulation, had said: “Calculations show that there is sufficient accumulated energy [in the MFT], now to produce an 8 magnitude earthquake. I cannot say when. It may not happen tomorrow, but it could possibly happen sometime this century, or wait longer to produce a much larger one.”

In a study published in the journal Nature Geoscience in December 2012, a research team led by Nanyang Technological University (NTU) discovered that massive earthquakes in the range of 8 to 8.5 magnitudes on the Richter scale had left clear ground scars in the central Himalayas

High resolution imagery and dating techniques showed that in 1255 and 1934, two great earthquakes ruptured the surface of the Earth in the Himalayas. The 1934 earthquake broke the surface over a length of more than 150 km.

The atom at the centre of the Earth

February 10, 2015

Last year it was 150 years since Jules Verne published his Journey to the Centre of the Earth. His basic premise was that some volcanic vents extended all the way from the surface to the Earth’s centre. His not unreasonable plot then made his heroes descend into the Icelandic volcano Snæfellsjökull, encountering many adventures, including prehistoric animals and natural hazards, before eventually coming to the surface again in southern Italy, at the Stromboli volcano”.

But physically reaching the centre of the Earth is probably more distant than even a human colony on a planet around Alpha Centauri. Speculations and models about what the Earth’s core is like is primarily based on the analysis of seismic waves and the manner in which they travel through the various layers making up the Earth’s interior.

A new analysis suggests that the Earth’s inner core has a further inner core. And probably that inner core has another inner core and so on ad infinitum! And even the one atom of Iron, right at the centre of the Earth, itself has an inner core called a nucleus.

Xiaodong Song et al. Equatorial anisotropy in the inner part of Earth’s inner core from autocorrelation of earthquake coda. Nature Geoscience, Feb 9, 2015

Song et al

Press ReleaseThe inner core, once thought to be a solid ball of iron, has some complex structural properties. The team found a distinct inner-inner core, about half the diameter of the whole inner core. The iron crystals in the outer layer of the inner core are aligned directionally, north-south. However, in the inner-inner core, the iron crystals point roughly east-west. (See graphic for a visual map of the inner core.)

Not only are the iron crystals in the inner-inner core aligned differently, they behave differently from their counterparts in the outer-inner core. This means that the inner-inner core could be made of a different type of crystal, or a different phase.

“The fact that we have two regions that are distinctly different may tell us something about how the inner core has been evolving,” Song said. “For example, over the history of the earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the key to how the planet has evolved. We are right in the center – literally, the center of the Earth.”

But this is all still modelling. It looks unlikely that we will be able to design a probe – let alone a vehicle – which can actually reach the centre of the Earth anytime soon. The centre of the Earth lies about 6,000km from the surface. The deepest level accessed physically by humans has been the 3400m that South African gold miners sometimes go down to. The deepest naturally occurring place that can be visited is probably the 2080m to the bottom of the Voronya cave in the Western Caucasus. The deepest oil wells are about 10 km deep. Possibly the deepest hole ever achieved is the Kola bore hole which reached 12,200m.

But who can tell? Maybe Jules Verne’s mysterious volcano tubes will one day be found.

Most of earth’s carbon could be in the inner core as iron carbide Fe7C3

December 2, 2014

The composition of the earth’s inner core is inferred from the speed of passage of seismic waves through the earth. It has generally been taken to be crystalline iron with some small amounts of nickel and lighter elements. But it has been necessary to assume that some part of the inner core is liquid to be able to explain why the S-wave travels at only about half the speed it should.

Now a new paper suggests that some of the core could well be iron carbide Fe7C3. The amounts of iron carbide needed would imply that our understanding of the carbon cycle is still in its infancy. Fully two-thirds of the earth’s carbon could be tied up in the inner core.

Bin Chen et al, Hidden carbon in Earth’s inner core revealed by shear softening in dense Fe7C3 , PNAS, doi: 10.1073/pnas.1411154111

The interior of the Earth (wikipedia)

 

Abstract: Earth’s inner core is known to consist of crystalline iron alloyed with a small amount of nickel and lighter elements, but the shear wave (S wave) travels through the inner core at about half the speed expected for most iron-rich alloys under relevant pressures. The anomalously low S-wave velocity (vS) has been attributed to the presence of liquid, hence questioning the solidity of the inner core. Here we report new experimental data up to core pressures on iron carbide Fe7C3, a candidate component of the inner core, showing that its sound velocities dropped significantly near the end of a pressure-induced spin-pairing transition, which took place gradually between 10 GPa and 53 GPa. Following the transition, the sound velocities increased with density at an exceptionally low rate. Extrapolating the data to the inner core pressure and accounting for the temperature effect, we found that low-spin Fe7C3 can reproduce the observed vS of the inner core, thus eliminating the need to invoke partial melting or a postulated large temperature effect. The model of a carbon-rich inner core may be consistent with existing constraints on the Earth’s carbon budget and would imply that as much as two thirds of the planet’s carbon is hidden in its center sphere.

From the press release:

“The model of a carbide inner core is compatible with existing cosmochemical, geochemical and petrological constraints, but this provocative and speculative hypothesis still requires further testing,” Li said. ” Should it hold up to various tests, the model would imply that as much as two-thirds of the planet’s carbon is hidden in its center sphere, making it the largest reservoir of carbon on Earth.”

It is now widely accepted that Earth’s inner core consists of crystalline iron alloyed with a small amount of nickel and some lighter elements. However, seismic waves called S waves travel through the inner core at about half the speed expected for most iron-rich alloys under relevant pressures.

Some researchers have attributed the S-wave velocities to the presence of liquid, calling into question the solidity of the inner core. In recent years, the presence of various light elements—including sulfur, carbon, silicon, oxygen and hydrogen—has been proposed to account for the density deficit of Earth’s core.

Iron carbide has recently emerged as a leading candidate component of the inner core. In the PNAS paper, the researchers conclude that the presence of iron carbide could explain the anomalously slow S waves, thus eliminating the need to invoke partial melting.

“This model challenges the conventional view that the Earth is highly depleted in carbon, and therefore bears on our understanding of Earth’s accretion and early differentiation,” the PNAS authors wrote. In their study, the researchers used a variety of experimental techniques to obtain sound velocities for iron carbide up to core pressures. In addition, they detected the anomalous effect of spin transition of iron on sound velocities. They used diamond-anvil cell techniques in combination with a suite of advanced synchrotron methods including nuclear resonant inelastic X-ray scattering, synchrotron Mössbauser spectroscopy and X-ray emission spectroscopy.

 

Species that developed while India moved from Gondwana to Asia

November 21, 2014

About 200 million years ago the land mass that is now the India plate was part of Gondwanaland. When this plate broke off from Gondwana around 135 million years ago it included what is now Madagascar but then left Madagascar behind as it began – by tectonic standards – a headlong rush north-eastwards around 90 million years ago. Till the collision of this plate with Asia around 10 million years ago brought about the formation of the Himalayas. For around 80 million years then the Indian land mass was an isolated island “rushing” north-east at between 16-20 cm/year!

From Gondwanaland to modern times image berkeley.edu

Indian plate tectonics (after Wikipedia)

(after wikipedia)

 

This period was also extraordinarily rich in the evolutionary history of the mammals. It was the time when snakes and ants first appeared. There was a mass extinction event about 66 million years ago. The dinosaurs disappeared and became birds. Birds proliferated and so did large flightless birds. The diversity of mammals exploded, perhaps just because of the space left by the disappearance of the large, unsuccessful dinosaurs. The first pigs and deer developed. The grasses arrived. Carnivorous mammals appeared as their prey increased. The first primates made an entrance. But whatever was evolving on the Indian land-mass was evolving largely in isolation from that taking place in the areas that were to become Africa and Eurasia. But there are tantalising indications that on its journey the Indian land-mass may have been connected for short periods by a land bridge to the Horn of Africa or to what is now Arabia.

A new paper reports on fossils from the edges of an open cast coal mine north east of Mumbai in Western India.

Kenneth D. Rose, Luke T. Holbrook, Rajendra S. Rana, Kishor Kumar, Katrina E. Jones, Heather E. Ahrens, Pieter Missiaen, Ashok Sahni, Thierry Smith. Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India. Nature Communications, 2014; 5: 5570 DOI: 10.1038/ncomms6570

The results suggest that an ancient relative of horses and rhinos lived 54.5 million years ago in what is now India. The findings shed light on the evolution of this group of animals. Several groups of mammals that appear at the beginning of the Eocene, including primates and odd- and even-toed ungulates, might have evolved in India while it was isolated.

John Hopkins Press ReleaseWorking at the edge of a coal mine in India, a team of Johns Hopkins researchers and colleagues have filled in a major gap in science’s understanding of the evolution of a group of animals that includes horses and rhinos. That group likely originated on the subcontinent when it was still an island headed swiftly for collision with Asia, the researchers report Nov. 20 in the online journal Nature Communications.

Modern horses, rhinos and tapirs belong to a biological group, or order, called Perissodactyla. Also known as “odd-toed ungulates,” animals in the order have, as their name implies, an uneven number of toes on their hind feet and a distinctive digestive system. Though paleontologists had found remains of Perissodactyla from as far back as the beginnings of the Eocene epoch, about 56 million years ago, their earlier evolution remained a mystery, says Ken Rose, Ph.D., a professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine.

An artist’s depiction of Cambaytherium thewissi via Science Daily Credit: Elaine Kasmer

The mine yielded what Rose says was a treasure trove of teeth and bones for the researchers to comb through back in their home laboratories. Of these, more than 200 fossils turned out to belong to an animal dubbed Cambaytherium thewissi, about which little had been known. The researchers dated the fossils to about 54.5 million years old, making them slightly younger than the oldest known Perissodactyla remains, but, Rose says, it provides a window into what a common ancestor of all Perissodactyla would have looked like. “Many of Cambaytherium’s features, like the teeth, the number of sacral vertebrae, and the bones of the hands and feet, are intermediate between Perissodactyla and more primitive animals,” Rose says. “This is the closest thing we’ve found to a common ancestor of the Perissodactyla order.”

Cambaytherium and other finds from the Gujarat coal mine also provide tantalizing clues about India’s separation from Madagascar, lonely migration, and eventual collision with the continent of Asia as the Earth’s plates shifted, Rose says. In 1990, two researchers, David Krause and Mary Maas of Stony Brook University, published a paper suggesting that several groups of mammals that appear at the beginning of the Eocene, including primates and odd- and even-toed ungulates, might have evolved in India while it was isolated. Cambaytherium is the first concrete evidence to support that idea, Rose says. But, he adds, “It’s not a simple story.”

“Around Cambaytherium’s time, we think India was an island, but it also had primates and a rodent similar to those living in Europe at the time,” he says. “One possible explanation is that India passed close by the Arabian Peninsula or the Horn of Africa, and there was a land bridge that allowed the animals to migrate. But Cambaytherium is unique and suggests that India was indeed isolated for a while.”

 

 

 

More evidence of water in the earth’s interior

March 13, 2014

There could be much more water trapped with minerals deep in the earth’s interior than all the surface water in the oceans.

D. G. Pearson, F. E. Brenker, F. Nestola, J. McNeill, L. Nasdala, M. T. Hutchison, S. Matveev, K. Mather, G. Silversmit, S. Schmitz, B. Vekemans, L. Vincze.Hydrous mantle transition zone indicated by ringwoodite included within diamondNature, 2014; 507 (7491): 221 DOI: 10.1038/nature13080

Deep Earth

Ringwoodite is thought to form between 410km and 660km beneath the Earth’s surface graphic BBC

BBC: Diamonds, brought to the Earth’s surface in violent eruptions of deep volcanic rocks called kimberlites, provide a tantalising window into the deep Earth.A research team led by Professor Graham Pearson of the University of Alberta, Canada, studied a diamond from a 100 million-year-old kimberlite found in Juina, Brazil, as part of a wider project. They noticed that it contained a mineral, ringwoodite, that is only thought to form between 410km and 660km beneath the Earth’s surface, showing just how deep some diamonds originate. 

While ringwoodite has previously been found in meteorites, this is the first time a terrestrial ringwoodite has been seen. But more extraordinarily, the researchers found that the mineral contains about 1% water. While this sounds like very little, because ringwoodite makes up almost all of this immense portion of the deep Earth, it adds up to a huge amount of deep water.

Dr Sally Gibson from the University of Cambridge, who was not involved in the work, commented: “Finding water in such large concentrations is a hugely significant development in our understanding of the ultimate origin of water now present at Earth’s surface.”

University of Alberta Press Release:

BlueRingwoodite.jpg

Crystal (~150 micrometers across) of Fo90 composition blue ringwoodite synthesized at 20 GPa and 1200 °C. Wikipedia

…. discovered the first-ever sample of a mineral called ringwoodite. Analysis of the mineral shows it contains a significant amount of water—1.5 per cent of its weight—a finding that confirms scientific theories about vast volumes of water trapped 410 to 660 kilometres beneath the Earth, between the upper and lower mantle.

“This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area,” said Pearson, a professor in the Faculty of Science, whose findings were published March 13 in Nature. “That particular zone in the Earth, the transition zone, might have as much water as all the world’s oceans put together.”

…. Ringwoodite is a form of the mineral peridot, believed to exist in large quantities under high pressures in the transition zone. Ringwoodite has been found in meteorites but, until now, no terrestrial sample has ever been unearthed because scientists haven’t been able to conduct fieldwork at extreme depths.

Pearson’s sample was found in 2008 in the Juina area of Mato Grosso, Brazil, where artisan miners unearthed the host diamond from shallow river gravels. The diamond had been brought to the Earth’s surface by a volcanic rock known as kimberlite—the most deeply derived of all volcanic rocks.

……. Scientists have been deeply divided about the composition of the transition zone and whether it is full of water or desert-dry. Knowing water exists beneath the crust has implications for the study of volcanism and plate tectonics, affecting how rock melts, cools and shifts below the crust.

“One of the reasons the Earth is such a dynamic planet is because of the presence of some water in its interior,” Pearson said. “Water changes everything about the way a planet works.”

Supervolcanos can erupt sponataneously without an external trigger

January 7, 2014

New research suggests that supervolcanos do not need an external trigger to erupt. Bouyancy effects and the magma volume could be sufficient for spontaneous eruption.

Wim J. Malfait, Rita Seifert, Sylvain Petitgirard, Jean-Philippe Perrillat, Mohamed Mezouar, Tsutomu Ota, Eizo Nakamura, Philippe Lerch, Carmen Sanchez-Valle. Supervolcano eruptions driven by melt buoyancy in large silicic magma chambersNature Geoscience, 2014; DOI:10.1038/ngeo2042

From the Press Release:

Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger. The results are published in Nature Geosciences.

A well-known supervolcano eruption occurred 600,000 years ago in Wyoming in the United States, creating a huge crater called a caldera, in the centre of what today is Yellowstone National Park. When the volcano exploded, it ejected more than 1000 km3 of ash and lava into the atmosphere, 100 times more than Mt Pinatubo in the Philippines did in 1992. Big volcanic eruptions have a major impact on the global climate. The Mt Pinatubo eruption decreased the global temperature by 0.4 degrees C for a few months. The predictions for a super volcano are a fall in temperatures by 10 degrees C for 10 years.

Abstract: Super-eruptions that dwarf all historical volcanic episodes in erupted volume and environmental impact are abundant in the geological record. Such eruptions of silica-rich magmas form large calderas. The mechanisms that trigger these super-eruptions are elusive because the processes occurring in conventional volcanic systems cannot simply be scaled up to the much larger magma chambers beneath supervolcanoes. Over-pressurization of the magma reservoir, caused by magma recharge, is a common trigger for smaller eruptions, but is insufficient to generate eruptions from large supervolcano magma chambers. Magma buoyancy can potentially create sufficient overpressure, but the efficiency of this trigger mechanism has not been tested. Here we use synchrotron measurements of X-ray absorption to determine the density of silica-rich magmas at pressures and temperatures of up to 3.6 GPa and 1,950 K, respectively. We combine our results with existing measurements of silica-rich magma density at ambient pressures to show that magma buoyancy can generate an overpressure on the roof of a large supervolcano magma chamber that exceeds the critical overpressure of 10–40 MPa required to induce dyke propagation, even when the magma is undersaturated in volatiles. We conclude that magma buoyancy alone is a viable mechanism to trigger a super-eruption, although magma recharge and mush rejuvenation, volatile saturation or tectonic stress may have been important during specific eruptions.

Supervolcanos do not occur all that often – perhaps one every 50,000 to 100,000 years. When they do occur they devastate a large geographical area and affect the climate for a decade or so. How much destruction of organic life occurs depends on the geographical area affected and the life that is extant there.

New Zealand’s Taupo Volcano was the most recent and erupted about 26,500 years ago. With a VEI of 8, just over 1,000 kmof ash were ejected. Though modern man had reached Australia by then, the effects of this eruption do not seem to have significantly delayed the march of humans. The Toba eruption 74,000 years ago occurred when the total population of all human species (Modern Humans, Neanderthals, Denisovans …..) was between 1 and 10 million. This eruption is also classified as a VEI of 8 and 2,800 km³ of material was ejected. Life was virtually extinguished from India to South East Asia. The effects were devastating not only in the fall out-zone but also – it seems – in hampering the expansion of modern humans out of AfricarabiaThis eruption may thus have caused one of the critical bottlenecks which has determined the subsequent evolution and expansion of humans. 

Image

Toba Fallout (Smithsonian Institute)

While a supervolcano could erupt at any time, it is much more probable to occur than a major asteroid collision with the earth (one in 100,000 years as opposed to once in tens of millions of years). But the volume of magma involved suggests that some early detection (perhaps 5 -10 years) may be possible. For the pressure to build up sufficiently in such a volume a significant bulging of the earth’s crust is likely and should be detectable. But while science fiction can imagine a battery of nuclear warheads to divert an oncoming asteroid in its trajectory, it is difficult to conceive of any way to prevent a supervolcano from erupting. Geo-engineering on a  scale massive enough to relieve some of the pressure in the magma is just conceivable at the edge of fantasy but even that could not prevent the eruption.

Increasing Antarctic sea ice correlates with global cooling

August 18, 2013

A new paper shows that for the last 30 years Antarctic ice is increasing and correlates best with a cooling global temperature.

Qi Shu, Fangli Qiao, Zhenya Song and Chunzai Wang, Sea ice trends in the Antarctic and their relationship to surface air temperature during 1979–2009, Clim Dyn (2012) 38:2355–2363, DOI 10.1007/s00382-011-1143-9

Abstract: Surface air temperature (SAT) from four reanalysis/analysis datasets are analyzed and compared with the observed SAT from 11 stations in the Antarctic. It is found that the SAT variation from Goddard Institute for Space Studies (GISS) is the best to represent the observed SAT. Then we use the sea ice concentration (SIC) data from satellite measurements, the SAT data from the GISS dataset and station observations to examine the trends and variations of sea ice and SAT in the Antarctic during 1979–2009. The Antarctic sea ice extent (SIE) shows an increased trend during 1979–2009, with a trend rate of 1.36 ± 0.43% per decade. Ensemble empirical mode decomposition analysis shows that the rate of the increased trend has been accelerating in the past decade. Antarctic SIE trend depends on the season, with the maximum increase occurring in autumn. If the relationship between SIC and GISS SAT trends is examined regionally, Antarctic SIC trends agree well with the local SAT trends in the most Antarctic regions. That is, Antarctic SIC and SAT show an inverse relationship: a cooling (warming) SAT trend is associated with an upward (downward) SIC trend.

The variations of local  SIC and SAT anomalies in autumn during the past 30 years

The variations of local
SIC and SAT anomalies in
autumn during the past 30 years

Summary: ….

The SAT and SIC trends illustrate an inverse relationship in most of the Antarctic regions, especially in summer and autumn. This indicates that a cooling (warming) SAT trend is associated with an upward (downward) SIC trend in the Antarctic. The station observations also confirm the inverse relationship between SAT and SIC. In most of the Antarctic regions, a cooling trend of SAT in summer and autumn is associated with an increased trend of SIC. …

Our analyses show that the relationship between sea ice and SAT trends should be examined regionally rather than integrally.


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