Tag Archives: tectonic

Tamu Massif is an intriguing new type of hybrid volcano

Tamu, the largest volcano on Earth, shares characteristics of both a mid-ocean ridge and a shield volcano. Its unique characteristics may force us to rethink a classic volcano formation theory.

A 3D map of Tamu Massif, the largest known volcano on Earth. It is around 4 miles high from its base and around 120,000 square miles across — approximately the size of New Mexico. Image credits: IODP.

When the Tamu Massif was discovered in September 2013, researchers suspected that it might be a single volcano. If this were, in fact, the case, it would make Tamu the single largest shield volcano on the globe. A new study, however, casts doubt on that idea — but shows that Tamu might be even more interesting than we thought.

Tamu is an extinct volcano, dating from the Mesozoic, some 145 million years ago. It is located 1,600 km (990 mi) east of Japan at a spreading ridge triple junction, where three tectonic plates are diverging from each other. However, Tamu was considered to be a shield volcano, comprising almost entirely of fluid lava flows from an emerging mantle plume.

This might not be the case.

Spreading ocean ridges typically form large volcanoes themselves. They also have a very distinct magnetic signature, which researchers can analyze. Essentially, whenever lava comes up the surface it solidifies, and the magnetic minerals inside it tend to align to the Earth’s magnetic poles — like compass needles frozen in time.

The magnetic poles are in constant movement, so when the next generation of lava bubbles up, those minerals will have a slightly different magnetic alignment, and so on. This magnetic analysis can also highlight polarity changes in the magnetic poles, which researchers can then detect.

Depiction of polarity around an ocean ridge. Image credits: WHOI.

Linear magnetic anomalies formed by the three ridges had previously been found around Tamu Massif, but it was unclear whether they continued within the volcano itself. Existing information seemed to suggest that this was not the case, hence the argument for Tamu being a shield volcano.

Now, a team of researchers from Texas, China, and Japan analyzed data from 4.6 million magnetic field readings carried over 54 years by ship tracks carrying magnetic measurement equipment. They also had new surveys over the area, finding that linear magnetic anomalies around Tamu Massif blend into linear anomalies over the mountain itself, indicating that the ridge is directly connected to the volcano formation.

“For Tamu Massif, we find dominantly linear magnetic field anomalies caused by crustal blocks of opposite magnetic polarity. This pattern suggests that Tamu Massif is not a shield volcano, but was emplaced by voluminous, focused ridge volcanism,” the study reads.

This is important because it suggests that the Tamu Massif (and potentially other similar areas) were formed through entirely different processes than we thought. A commonly accepted model in volcanology suggests that a hotter (and therefore, lighter) blob of magma, called a mantle plume, slowly rises through the mountain. This plume creates a volcano when it reaches the surface through a vertical succession of lava flows.

But in the case of Tamu, this succession is lateral, not vertical, which the mantle plume theory struggles to incorporate.

Depiction of a mantle plume. This explains many of the earth’s volcanic systems, but not Tamu. Image via Wikipedia.

William Sager, a geophysicist at the University of Houston and senior author for the paper, was one of the authors of the study which concluded that Tamu is likely a shield volcano, but he says questioning old ideas and putting them to the test is an essential part of science.

“Science is a process and is always changing. There were aspects of that explanation that bugged me, so I proposed a new cruise and went back to collect the new magnetic data set that led to this new result.”

“In science, we always have to question what we think we know and to check and double check our assumptions. In the end, it is about getting as close to the truth as possible—no matter where that leads.”

Also, in light of these findings, Tamu also can’t be considered the world’s largest shield volcano, since it’s not a shield volcano. That honor flows back to Mauna Loa, on the island of Hawaii. As for the largest overall volcanic system in the world, that is dominated by the mid-ocean ridges.

“The largest volcano in the world is really the mid-ocean ridge system, which stretches about 65,000 kilometers around the world, like stitches on a baseball,” Sager said. “This is really a large volcanic system, not a single volcano.”

The study ‘Oceanic plateau formation by seafloor spreading implied by Tamu Massif magnetic anomalies’ has been published in Nature Geosciences

Tibetan Plateau.

A shattered tectonic plate underpins the Tibetan Plateau — explaining the area’s weird earthquakes

A new geophysical model shines some light on the Tibetan Plateau’s unique geology.

Tibetan Plateau.

Natural-color image of the Tibetan Plateau.
Image credits NASA Earth Observatory.

Some 50 million years ago, India was a huge hit in Asia — quite literally, as the peninsula smashed into the continent after breaking up with Gondwana, creating the Himalayas of today. We don’t know very much about the specifics of this collision, as the Tibetan Plateau — an area at the epicenter of this collision — is quite inhospitable and hard to reach, for earth scientists and laymen alike.

New research, led by scientists from the University of Illinois at Urbana-Champaign, comes to shed more light on the event. Not only do the findings help patch our understanding of the area’s geology. The results also help explain the highly-peculiar — and very violent — seismic activity in this area.

Shaking things up

“The continental collision between the Indian and Asian tectonic plates shaped the landscape of East Asia, producing some of the deadliest earthquakes in the world,” said Xiaodong Song, a geology professor at the University of Illinois and co-author of the new study.

“However, the vast, high plateau is largely inaccessible to geological and geophysical studies.”

Song and his team drew on high-resolution seismic (earthquake) data to generate the clearest model of the Tibetan Plateau’s geology to date. They pooled together geophysical data from various studies and other sources, and collated them to generate seismic tomography images of Tibet — think of them as ultrasound imaging for geology — that peer down to about 160 kilometers under the surface.

Their work reveals that the upper mantle layer of the Indian tectonic plate is broken into four distinct pieces that push under the Eurasian plate. Each of these four fragments lies at a different distance from the origin of the tear and moves at a different angle relative to the surface than its peers. The new data match well with recorded earthquake activity, geological, and geochemical observations in the area, the team writes, which helps improve confidence in the results.

Model Tibet Plateau.

Seismic wave velocity images of the Tibetan Plateau in image a (map view) and image b (cross-section view). In image b, T1, T2 and T3 mark mantle tears, the circles indicate earthquakes deeper than 40 kilometers and the white contours show earthquake density.
Image credits Jiangtao Lia, Xiaodong Songa, (2018), PNAS.

“The presence of these tears helps give a unified explanation as to why mantle-deep earthquakes occur in some parts of southern and central Tibet and not others,” Song said.

While the Indian plate was definitely shredded after the impact, the bodies of intact crust between the tears (the four fingers themselves) are still strong enough to accumulate strain — and such strain, when released, is what causes earthquakes. At the same time, heat upwelling from the deeper mantle can pass through the torn areas more readily. Areas of crust directly above the tears become more ductile and less susceptible to earthquakes as they warm.

This last tidbit of information helps explain the “unusual locations” of some of the earthquakes in the plateaus’ southern reaches, according to co-author Jiangtao Li, who adds that “there is a striking correlation with the location of the earthquakes and the orientation of the fragmented Indian upper mantle”.

The model also helps us get a better idea of the local geology as a whole, explaining some of the area’s more peculiar surface deformation patterns, such as a series of unusual north-south rifts along the plateau, for example. Such deformation patterns, together with the location of most earthquakes in the area, further suggest that the crust and upper mantle are strongly coupled in southern Tibet — i.e. surface rocks are very well ‘glued’ to deeper formations.

Simplified model.

Idealized cartoon illustration of the tearing of the Indian plate and coupling between the crust (orange) and the mantle lithosphere (blue) in south-central Tibet. The thickness of the crust and mantle lithosphere is not to scale. The white dashed line marks the possible boundary between the underthrusting Indian crust and the overriding Himalayan orogenic prism and Tibetan crust.
Image credits Jiangtao Lia, Xiaodong Songa, (2018), PNAS.

Overall, the findings offer a clearer picture of the state of the crust and upper mantle in the Tibetan Plateau. The findings will also help us better assess areas that are at risk from earthquakes, the team adds, with the potential to safeguard lives and property from their devastating effects.

The paper “Tearing of Indian mantle lithosphere from high-resolution seismic images and its implications for lithosphere coupling in southern Tibet” has been published in the journal Proceedings of the National Academy of Sciences.

Georgetown area while still attached to North America (left). About 100 million years later, Georgetown joined the North Australia landmass. Credit: Journal Geology.

Geologists say part of northern Australia was once stuck to North America

Geologists analyzed rocks collected from opposite sides of the world and concluded that they match. The conclusion: a part of Australia was once attached to North America about 1.7 billion years ago.

Georgetown area while still attached to North America (left). About 100 million years later, Georgetown joined the North Australia landmass. Credit: Journal Geology.

Georgetown area while still attached to North America (left). About 100 million years later, Georgetown joined the North Australia landmass. Credit: Journal Geology.

Australian scientists from Curtin University examined sandstone sedimentary rocks which formed in a shallow sea, collected from the Georgetown region in northern Queensland. From the get-go, these samples were peculiar they didn’t resemble any other rocks found in Australia. Instead, they matched rocks found in present-day Canada, as reported in the journal Geology

After much deliberation, the scientists hypothesize that Georgetown broke away from North America 1.7 billion years ago. After more slow, but steady, tectonic movement, Georgetown collided with what is now northern Australia, at Mount Isa, some 100 million years later.

Perhaps this sort of news sounds peculiar, but for geologists, this is anything but. Through Earth’s history spanning more than four billion years, landmasses have come together and drifted apart countless times and in various configurations, driven by the caprices of tectonic motion. For instance, some 300 million years ago, all of the continents came together to form one single supercontinent known as Pangaea. 

Pangaea likely wasn’t the only supercontinent in the planet’s geological history. Although scientists are still piecing together the jigsaw-puzzle pieces, they have good hints that another supercontinent called Nuna, sometimes known as Columbia, existed prior to Pangaea. Adam Nordsvan, a Curtin University doctoral student and lead author of the study, claims that some 300 million years after the event that separated Georgetown from North America, the supercontinent of Nuna disassembled into various landmasses.

“This was a critical part of global continental reorganization when almost all continents on Earth assembled to form the supercontinent called Nuna,” Nordsvan said in a statement.

Previous studies have suggested that northeastern Australia was adjacent North America, Siberia or North China when the continents came together to form Nuna. According to sedimentological and geochronological data, when Nuna started breaking up, the Georgetown area remained permanently stuck to Australia.

That’s not all. Colliding landmasses typically form mountain ranges. For instance, when the continental plates of India and Asia merged 55 million years ago, it resulted in the formation of the Himalayas. Nordsvan and colleagues say they have evidence that the Mount Isa mountain ranges formed when Georgetown and the rest of Australia rammed into each other.

“Ongoing research by our team shows that this mountain belt, in contrast to the Himalayas, would not have been very high, suggesting the final continental assembling process that led to the formation of the supercontinent Nuna was not a hard collision like India’s recent collision with Asia,” said study co-author Zheng-Xiang Li, also from Curtin’s School of Earth and Planetary Sciences.

“This new finding is a key step in understanding how Earth’s first supercontinent Nuna may have formed, a subject still being pursued by our multidisciplinary team here at Curtin University.”

Water on Mars

The Martian Polygons – An evidence for former Seafloors?

Intricate polygons on Mars could be a clear indication of a wet past for the Red Planet. Most crater floor polygons have diameters ranging from 15 to 350 m, and it’s still not clear how and why they appeared – though one theory seems to be gaining ground: the idea of former lake beds.

Water on Mars

Image 1. Typical crater floor polygons. [A] CTX (a 6 meter/pixel camera onboard the Mars Reconnaissance Orbiter, P16_007372_2474).of a 14 km‐sized impact crater

Polygons are some of the most common features at high latitudes on Mars. They have been observed by both lander and orbiting spacecraft. They range in size from 2 m all the way up to 10 km, and there is still an ongoing debate regarding their formation. Proposed mechanisms include thermal contraction, desiccation, volcanic, and tectonic processes; the polygons also bear similar resemblance to polygons observed on Earth, which took shape on the seafloor.

In 2000, an analytical model based on fracture mechanics (El Maarry et al., 2010) showed that through thermal changes alone (no water), the maximum fracture spacing attainable is 75 meters, with more probable values revolving around 20 meters – so this is clearly not the cause here. Also, no exact tectonic processes which can cause such formations have been identified – so the only plausible possibility left is a former sea floor.

On Earth, polygon-shaped areas, with the edges formed by faults, are common in fine-grained deep-sea sediments. Some of the best examples of these polygon-fault areas are found in the North Sea and the Norwegian Sea. We know this because the areas have been thoroughly surveyed through seismic techniques for offshore oil and gas deposits. While they are diverse and intricate, all polygons seem to have one thing in common – form in a common environment: sediments made up of fine-grained clays in ocean basins that are deeper than 500 meters, and when these sediments are only shallowly buried by younger sediments. The slope angle of the seafloor also plays a crucial role: when the slope is very gentle (or non existent), the shape of the polygons tends to remain unchanged. However, when there is some positive or negative topography, the shapes are often altered or broken down.

So if this is indeed the case on Mars (and there’s little reason why it shouldn’t be), it seems pretty clear that we’re dealing not only with a water body, but with a water body which was at least half a kilometer deep. Furthermore, the variation of crater floor polygons sizes with location can be indicative of different hydrologic environments. So not only was there likely water on Mars – but it was likely a big and complex system.

101 Dalmatians ?! Probe counts and maps the geysers on Enceladus

The geysers on the surface of Saturn’s moon Enceladus have been counted and mapped, strengthening theories that Enceladus is one of the best extraterrestrial places in our solar system to look for life.

Earth is not the only place in our solar system which holds water. For example, Enceladus also has liquid oceans – albeit ones covered by a thick layer of ice. Researchers believe that the oceans are kept liquid by heat generated by the gravitational stress which Saturn holds on its satellite. The tectonics of Enceladus is also surprisingly active, and one of the results are the 101 geysers on its surface.

Scientists are fairly sure that the gravitational pull keeps the ice melted and created these hot spots – but the exact mechanism through which the geysers form is still not clear; one theory is that huge chunks of ice act somewhat similar to tectonic plates, and the friction between their edges generates heat close to the surface. Another theory is that water boiling deeper flows to the surface, creating the surfaces we see today.

If you look at the map of the geysers on Enceladus, again, you see a similarity to Earth tectonics – the geysers are concentrate on distinct lines, like volcanoes are concentrated at the edge of tectonic plates here on Earth. In this case, the lines coincide with the areas of most stress.

“[This] strongly suggests that the heat accompanying the geysers is not produced by shearing in the upper brittle layer but rather is transported, in the form of latent heat, from a sub-ice-shell sea of liquid water, with vapor condensing on the near-surface walls of the fractures.”

Still, regardless of the formation mechanism, Enceladus seems like a very interesting place to look for alien life – something which you wouldn’t initially expect, for the satellite of a frozen gas giant like Saturn.

8.2 magnitude earthquake strikes Chile

An 8.2-magnitude earthquake hit near the coast of Chile last night, triggering multiple strong aftershocks and a 6-foot (3 meter) tsunami. There have been at least five confirmed casualties, with the victims being crushed or suffering from heart attacks.

“The fact is, we will know the extent of the damage as time goes by and when we inspect the areas in the light of day,” Chile’s President Michelle Bachelet said early Wednesday. “The country has faced these first emergency hours very well.”

The earthquake hit just 50 miles southwest of Cuya, Chile at 6.2 miles deep in the Pacific Ocean.

The tsunami warning also struck fear into Chilean people, but thankfully, the tsunami was relatively small in amplitude. However, the earthquake itself was very strong – the shaking was so strong that it was felt 300 miles away in Bolivia and aftershocks measured up to 6.2 in magnitude. However, while the extent of damage was considerable (landslides damaged roads in some regions, power and phone outages were reported in others), given the tectonic context, the situation could have been much worse.

Image Source.

Chile is located in one of the most volatile areas in the world – tectonically speaking. The country spans over the so-called “Ring of Fire” – the tectonic edge between the South American plate and the Nazca plate. The Nazca plate is slowly subducting (moving under) the South American plate, the most obvious result of which is the Andes Mountain range; this movement also causes massive earthquakes, as well as increased volcanic activity in the area.

Geologists worry that the energy is still not released, and Chile may have to face an even stronger event in the near future.

“As big as an 8.1 is, it probably has not released all of the stored up energy on the subduction earthquake fault in northern Chile. For the sake of all of our friends in the region, we’re hoping that there isn’t a bigger one still to come,” said geologist Rick Allmendinger.

Evidence of granite found on Mars – Red Planet geology more complex than previously thought

Geologists have now found the most compelling evidence of granites on Mars – something which prompts more complex theories about the geology and tectonic activity on the Red Planet.

Granites and basalts

Basalt and Granite. Credits: Rice University.

Granites are igneous rocks, pretty common on the surface of Earth. It is often called a ‘felsic’ (white rock) – because it is very rich in so-called white minerals, such as quartz or feldspar. It is contrasted with mafic rocks (for example basalt), which are relatively richer in magnesium and iron. Now, large amounts of feldspar have been found in a Martian volcano. Interestingly enough, minerals commonly found in basalts are completely absent from that area; considering how basalts are almost ubiquitous on Mars, this initially came as a shock, but now, geologists have come up with a theory to explain this.

Granite, or its eruptive equivalent, rhyolite, is often found on Earth in tectonically active regions such as subduction zones. However, since Mars isn’t tectonically active, there are no subduction zones there, so there has to be a different cause. The team studying the case concluded that prolonged magmatic activity on Mars can also produce these granitic compositions on very large scales.

“We’re providing the most compelling evidence to date that Mars has granitic rocks,” said James Wray, an assistant professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology and the study’s lead author.

Red Planet geology

A 'spectral window' into the Martian geology - bright magenta outcrops have a distinctive feldspar-rich composition. (Credit: NASA/JPL/JHUAPL/MSSS)

A ‘spectral window’ into the Martian geology – bright magenta outcrops have a distinctive feldspar-rich composition. (Credit: NASA/JPL/JHUAPL/MSSS)

For many years, the geology of Mars has been considered to be very simplistic, consisting of mostly one single type of rock: basalt – a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface. The dark rock can also be found on Earth in many volcanically active areas, such as Hawaii or Iceland for example.

But earlier this year, the Mars Curiosity started to cast some doubt on those beliefs, when it reported finding soils with a composition similar to granite. No one really knew what to make of this discovery, but since it appeared to be very localized, it was just considered a local anomaly. However, this new research analyzed things at a much larger scale, using remote sensing techniques with infrared spectroscopy to survey a large volcano on Mars that was active for billions of years. The volcano is perfect for this type of study, because it is dust free (a true rarity on Mars) – some of the fastest-moving sand dunes on Mars sweep away any would-be dust particles on this volcano.

Much to the delight of researchers, the limitations of the remote sensing technology were an advantage in this case:

“Using the kind of infrared spectroscopic technique we were using, you shouldn’t really be able to detect feldspar minerals, unless there’s really, really a lot of feldspar and very little of the dark minerals that you get in basalt,” Wray said.

Separating the white and the black

So we have an island of white feldspar amidst an ocean of black basalt – how did it form?

When you have magma in the subsurface, it cools off very, very slowly. In a tectonically inactive planet like Mars, this process can be very stable. While the magma slowly cools off, low density melt separates from high density crystals, and if the conditions are just right, this process can take place for billions of years, leading to the creation of granitic rocks, as computer simulations showed.

“We think some of the volcanoes on Mars were sporadically active for billions of years,” Wray said. “It seems plausible that in a volcano you could get enough iterations of that reprocessing that you could form something like granite.”

While we are trying to figure out the existence (or lack of it) of life on Mars, this is another wake-up call, showing just how little we understand about the geologic processes on the Red Planet – which ultimately govern the appearance of life. Anyway, the geology of Mars just got a lot more interesting.

Journal Reference:

  1. James J. Wray, Sarah T. Hansen, Josef Dufek, Gregg A. Swayze, Scott L. Murchie, Frank P. Seelos, John R. Skok, Rossman P. Irwin, Mark S. Ghiorso. Prolonged magmatic activity on Mars inferred from the detection of felsic rocksNature Geoscience, 2013; DOI: 10.1038/NGEO1994

Ancient, long-lost continent found under the Indian Ocean

Evidence of drowned remnants of an ancient microcontinent have been found in sand grains from the beaches of a small Indian Ocean island, according to a new research.

Zircons and volcanoes

mauritia

This evidence was found in Mauritius, a volcanic island 900 kilometres east of Madagascar which serves as an exotic destination for many tourists. Basaltic rocks from the island have been dated to approximately 9 million years ago, but now, an international research team analyzed the beaches and found fragments of zircon that are much older, between 600 million and 2 billion years old.

Bjørn Jamtveit, a geologist at the University of Oslo explained that the zircons had crystallized within granites or other acidic igneous rocks (basalts being basic, non acidic). He believes that rocks containing these minerals came from a long-submerged landmass that was once wedged between India and Madagascar in a prehistoric supercontinent known as Rodinia; geologically recent volcanic eruptions brought the rocks up to the surface, where they were eroded, resulting in the shards they picked up. Most of the rocks were melted by the high temperatures, but some grains of zircons survived and were frozen into the lavas, rolling towards the Mauritian surface.

“When lavas moved through continental material on the way towards the surface, they picked up a few rocks containing zircon,” study co-author Bjørn Jamtveit, a geologist at the University of Oslo in Norway, explained in an email.

rodinia

The tectonic plates are mobile in geologic time – the surface of the Earth didn’t always look like this. As a matter of fact, the further down you go on the time scale, the more different it looks like. According to plate tectonic reconstructions, Rodinia existed between 1.1 billion and 750 million years ago; virtually all of the Earth’s landmass was concentrated in this single supercontinent which started to split 3/4 billion years ago.

The study also analyzed the gravity field and as it turns out, something really interesting happened to the remains of Rodinia in that area. As India and Madagascar began to drift apart some 85 million years ago, the landmass just sinked, Atlantis style. The cause was tectonic rifting and sea-floor spreading sending the Indian subcontinent surging northeast, sinking the fragments of Mauritia (how the researchers named this microcontinent).

The variations in the gravitational field observed in some areas in Mauritius, the Seychelles, and the Maldives is pretty much a smoking gun suggesting a thick crust supporting the long-lost continent theory, with the continent being “tucked” under the Indian Ocean.

gravity

A non-geologic accident?

The only weak point, is that the study, thorough as it is, relies mostly on those zircons; couldn’t they be just some sort of non-geologic accident?

“There’s no obvious local source for these zircons,” says Conall Mac Niocaill, a geologist at the University of Oxford, UK, who was not involved in the research.

It also doesn’t look like they were brought there by winds.

“There’s a remote possibility that they were wind blown, but they’re probably too large to have done so,” adds Robert Duncan, a marine geologist at Oregon State University in Corvallis.

Also, the samples were picked up from remote sites, where it’s quite unlikely that humans would have brought them there. However, Jérôme Dyment, a geologist at the Paris Institute of Earth Physics in France, is not convinced. He believes that a number of non-geologic processes could have brought the minerals there, as part of ship ballast or modern construction material for example.

“Extraordinary claims require extraordinary evidence, which are not given by the authors so far,” said Dyment, who did not participate in the research. “Finding zircons in sand is one thing, finding them within a rock is another one … Finding the enclave of deep rocks that, according to the author’s inference, bring them to the surface during an eruption would be much more convincing evidence.”

He makes an even more convincing argument, explaining that if remains of such a continent were to exist, evidence for its existence should have been found as part of an ongoing experiment that installed deep-sea seismometers to investigate Earth’s mantle around Réunion Island, which is situated about 200 kilometers from Mauritius.

So is this compelling evidence, or is it more of an educated assertion? But Conall Mac Niocaill, a geologist at the University of Oxford in the U.K. who was also not involved in the study, is spot on: “the lines of evidence are, individually, only suggestive, but collectively they add up to a compelling story.”, he says. Particularly, the geophysic (gravimetric) evidence is highly consistent with the researchers’ claims. All in all, it paints a consistent picture which makes sense in a tectonic context, but as almost always in geology, you can’t just draw a line and say “This is so”; one thing’s for sure though: oceanic basins worldwide may very well host similarly submerged remains of “ghost continents”.

Via Nature Geoscience

Oxygen atmosphere on Saturn’s moon, Dione

It’s been less than a month since we published the last thing about the Cassini probe, and the amazing spacecraft has done it again; this time it detected a thin, oxygen atmosphere, on a moon of Saturn – Dione. The study was published in the Geophysical Research Letters

At 1122 km in diameter, Dione is the 15th largest moon, and the last significant one – larger than all the rest of the planet’s moons put together. Since its formation, Dione has definitely undergone some interesting geological processes, as pictures shown again by Cassini in 2004 revealed what are believed to be ice cliffs created by tectonic fractures, hundreds of meters tall or even more. Some believe that ice volcanism also played a role in the process of shaping the planet.

Now, more recently, the Cassini probe signaled the existence of an oxygen atmosphere in the planet, but don’t get too excited about moving there: the atmosphere is three trillion times thinner than on the surface of Earth – pretty much what you’d expect to see some 300 km above ground here. Still, that’s enough to classify it as an atmosphere, and astronomers are pretty excited about this find, not necessarily in itself, but in the implications it carries.

We now know that Dione, in addition to Saturn’s rings and the moon Rhea, is a source of oxygen molecules,” Cassini team member Robert Tokar of the Los Alamos National Laboratory in New Mexico, who led the new study, said in a statement. “This shows that molecular oxygen is actually common in the Saturn system and reinforces that it can come from a process that doesn’t involve life.”

The oxygen on Dione may be created by solar photons or high-energy particles that bombard the moon’s icy surface, kicking up oxygen atoms in the process. Another theory is that the previous geological events supplied the necessary oxygen for this atmosphere. Either way, this discovery came as quite a shock to many.

“Scientists weren’t even sure Dione would be big enough to hang on to an exosphere, but this new research shows that Dione is even more interesting than we previously thought,” said Amanda Hendrix, the deputy project scientist for Cassini at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who did not participate in Tokar’s study. “Scientists are now digging through Cassini data on Dione to look at this moon in more detail.”

Nuclear fission amounts for half of Earth’s heat and energy

The relatively new theory of plate tectonics is still uncertain about what is the driving force behind the tectonic movement; now, scientists working at the Kamioka Liquid-Scintillator Antineutrino Detector (KamLAND) and the Borexino Detector believe they are close to finding out the answer to that question, after using neutrino detectors and measuring the flow of the antithesis of these neutral particles as they emanate from our planet. Nuclear fission would also amount for half of the Earth’s heat.

Neutrinos and antineutrinos are extremely interesting particles. They are electronic particles that travel at a speed closer to the speed of light, and can move freely through mass and space due to their lack of electronic charge; the magmatic rocks within our planet all contain these particles, in radioactive elements such as uranium, potassium and thorium. Over the billions of years in our planet’s history, these elements have been radioactively decaying, producing heat, energy, as well as these neutrinos and antineutrinos, pretty much in the same way that a nuclear reactor does. Thus, these particles could be considered as a marker for estimating how much energy and heat was produced in this process.

So just how much heat are we talking about ? Researchers estimate that we are dealing with about 20 terawatts of heat, roughly double than what humanity is using at the present. This could also provide the necessary energy to literally move mountains, as has happened during the tectonic history.

Earth’s total heat is estimated at roughly 44 terawatts, a number estimated from calculations conducted on the very deep boreholes from the crust, so nuclear fission would be responsible for almost half of all that. The rest is a result of processes that took place when the Earth was formed, or during some other processes researchers have yet to uncover. Some of the heat is most likely trapped in the nickel-iron internal core of our planet, while the nuclear decay happens mostly in the mantle and in the crust. While there is still something to decay and this process continues, the continents will continue to move and collide, and from what can be estimated at this point, that will not happen for many millions of years.

Quartz may be key to plate tectonics

Plate tectonics is one of the most important theories, from the point of view of its practical effects on society – just look at the earthquake in Japan, or the iminent one in California, for example. More than 40 years ago, a man named J. Tuzo Wilson published a paper in Nature, describing how ocean basins open and close, in what is taught today in every geology course as the Wilson cycle. Basically, some ocean basins will shrink and become seas, or even disappear, and some sea basins will become ocean basins.

His observations, known today as the “Wilson Tectonic Cycle” suggested that this process took place numerous times in Earth’s troubled history, most recently when the supercontinent Pangaea split into the continents we know today. Wilson’s ideas are extremely important for plate tectonics, as well as the processes which lie at the very core of earthquake formation and mountain genesis.

Since his paper was published in 1967, pretty much every study conducted on the topic supported this idea, but few managed to bring additional information. Now, new findings by Utah State University geophysicist Tony Lowry and colleague Marta Pérez-Gussinyé of Royal Holloway, University of London offered an interesting point of view on the whole subject.

“It all begins with quartz,” says Lowry, who published results of the team’s recent study in the March 17 issue of Nature.

The scientists used and described a new way of measuring the properties of the rocks located beneath the deep crust. This way reveals events that cause the Earth’s surface to crack, fold and stretch, and it displays the key role played by quartz.

“If you’ve ever traveled westward from the Midwest’s Great Plains toward the Rocky Mountains, you may have wondered why the flat plains suddenly rise into steep peaks at a particular spot,” Lowry says. “It turns out that the crust beneath the plains has almost no quartz in it, whereas the Rockies are very quartz-rich.”

He believes that it’s exactly those belts of quartz that set in motion the chain of events which leads to the mountain building rock cycle.

“Earthquakes, mountain-building and other expressions of continental tectonics depend on how rocks flow in response to stress,” says Lowry. “We know that tectonics is a response to the effects of gravity, but we know less about rock flow properties and how they change from one location to another.”

“Over the last few decades, we’ve learned that high temperatures, water and abundant quartz are all critical factors in making rocks flow more easily,” Lowry says. “Until now, we haven’t had the tools to measure these factors and answer long-standing questions.”

But now, thanks to EarthScope, that has all changed.

“This intriguing study provides new insights into the processes driving large-scale continental deformation and dynamics,” says Greg Anderson, NSF program director for EarthScope. “These are key to understanding the assembly and evolution of continents.”

“We’ve combined Earthscope data with other geophysical measurements of gravity and surface heat flow in an entirely new way, one that allows us to separate the effects of temperature, water and quartz in the crust,” Lowry says.

They found that even at a low seismic velocity ratio, even after separating the temperatures, quartz-rich crust appears in pretty much the same places as high lower-crustal temperatures modeled independently from surface heat flow.

“That was a surprise,” he says. “We think this indicates a feedback cycle, where quartz starts the ball rolling.”

However, if the temperature and water are the same, rock flow will tend to focus on the quartz because that is the weak link.

“Rock, when it warms up, is forced to release water that’s otherwise chemically bound in crystals,” he says

More info about the Earth Scope Project here

Insects trapped in amber offer a precious glimpse on prehistoric bugs

Amber is not very common, but you can’t say it’s really uncommon either. Bugs in amber – that’s rare, but a huge “stash” such as the one that was found in India – that’s really something out of this world. The bug “collection” that was unearthed seems to suggest that the Indian continent was not really as isolated as previously thought. The findings were published in PNAS (Proceedings of the National Academy of Sciences).

“We know India was isolated, but … the biological evidence in the amber deposit shows that there was some biotic connection,” says David Grimaldi, curator in the Division of Invertebrate Zoology at the [American Museum of Natural History].

Here’s your basic tectonic for you: as you (should) know, the continents looked quite differently 150 million years ago than they do now. Back then, the Indian plate had just separated from the African one and started a journey towards Asia that would last 100 million years, during which the Indian subcontinent was quite isolated from the rest of the world. The fact that it was isolated allowed it to develop some unique and interesting species, including bugs such as the one in the pictures, that lived some 50 million years ago.

“The amber shows, similar to an old photo, what life looked like in India just before the collision with the Asian continent,” says Jes Rust, professor of Invertebrate Paleontology at the Universität Bonn in Germany. “The insects trapped in the fossil resin cast a new light on the history of the sub-continent.”

Many arthropodes are very similar to the ones found in Asia at the time, which leads to the logical conclusion that the two continents had some sort of connection even before they united. The other possibility would rock the scientific world even more, because it could only suggest that the two plates merged earlier than believed.

“They are so well preserved. It’s like having the complete dinosaur, not just the bones. You can see all the surface details on their bodies and wings. It’s fantastic,” Rust told the Guardian.

Just so you can make an idea about how big of a finding this is, it weighs around 150 kilograms and it is about 52 million years old. Not only do the insects give extremely valuable clues, but the amber itself has something to say. The original resin came from a tropical tree family called Dipterocarpaceae that today makes up about 80 percent of forest canopies in Southeast Asia, which makes the tree family and tropical forests in general twice as old as previously believed; and just think, all this, all of this amazing information can be taken from insects trapped in amber !

“The evidence is beginning to accumulate that tropical forests are ancient,” Grimaldi said. “They probably go back to right after the K-T boundary,” between the Cretaceous and Tertiary periods 65 million years ago, when non-avian dinosaurs went extinct.