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Ancient supervolcanoes threw rocks right across Australia

Ancient supervolcanoes threw rocks right across Australia. Science & Technology World Website


How's your throwing arm? Probably not as good as the ancient supervolcanoes in Australia, which scientists have discovered had enough explosive power to fling rocks to the other side of the country – more than 1,400 miles (2,253 kilometres) away.

The research is helping us understand more about how the continent, and its unique landscapes, once formed.

It's long been known that the east coast of Australia is home to ancient supervolcanoes, but what wasn't clear until now was what kind of role they played in forming the country.

To figure this out, a team from Curtin University in Western Australia analysed the age and composition of geological material across the west side of the country.

The study revealed sand-sized zircon crystals that didn't match up with any of the typical rock composition in Western Australia – but that did reflect the volcanic rock of the Whitsundays area in north-east Australia, in terms of both age and geochemicals.


Ancient supervolcanoes threw rocks right across Australia. Science & Technology World Website


That suggests that the giant volcanoes that were once dotted the north-eastern coast belched rocks far and wide – including all the way to the other side of the country. Until now, the local craters and solidified lava flows were all researchers had to go on when estimating the size of these ancient eruptions.

"Such distal projection of a unique volcanic mineral population demonstrates that super-eruptions were occurring in eastern Australia approximately 106 million years ago, during the break-up of the supercontinent Gondwana," said lead researcher, Milo Barham.

Based on an analysis of the arrangement of land masses and atmospheric conditions at the time, it looks like the super-eruptions happened during the southern hemisphere's winter, when strong winds from the east would have helped to push the volcanic rock westwards, according to Barham.

If the scientists' hypothesis is right, the super-eruptions would've been tens to hundreds of times more powerful than any in recorded history, reports Alice Klein for New Scientist.

Were such an eruption to happen today in Queensland, it would be heard all the way over in Perth.

Being able to get insight into eruptions of this type is important to scientists studying the changes that have happened to Earth's climate over time – an eruption that would have been powerful enough to blast rocks thousands of kilometres would most likely have had a significant cooling effect as well.

But the research will also help the team trace the evolution of different species, and help scientists to predict when and if eruptions of this strength will happen again. 

Because it's not just ancient supervolcanoes that can toss material this far. The Eyjafjallajökull eruptions in 2010 were much smaller but are the most recent modern example of how debris and ash can be blown across huge distances – with the ash cloud spreading thousands of kilometres and disrupting air travel around the world.

The biggest super-eruption on record, meanwhile, came from the Toba volcano in Indonesia some 75,000 years ago.

In that case, sand-sized particles were blown over a 1,700-mile (2,735-km) radius, as shown by ash layers found deep below the ocean, but experts are divided on how much of an impact the blast had on the planet's climate.

Peering back this far into history isn't easy, but the more data scientists have access to, the better they can piece together what happened.

"The incomplete nature of geological sequences means that recognising these earth-shattering volcanic events is difficult in deeper geological time, millions to billions of years ago," said Barham.

The research has now been published in Geology.


What are the benefits of volcanoes?

What are the benefits of volcanoes? Science & Technology World Website


Volcanoes are renowned for their destructive power. In fact, there are few forces of nature that rival their sheer, awesome might, or have left as big of impact on the human psyche. Who hasn't heard of tales of Mt. Vesuvius erupting and burying Pompeii? There's also the Minoan Eruption, the eruption that took place in the 2nd millennium BCE on the isle of Santorini and devastated the Minoan settlement there.

In Japan, Hawaii, South American and all across the Pacific, there are countless instances of eruptions taking a terrible toll. And who can forget modern-day eruptions like Mount St. Helens? But would it surprise you to know that despite their destructive power, volcanoes actually come with their share of benefits? From enriching the soil to creating new landmasses, volcanoes are actually a productive force as well.

Soil Enrichment:

Volcanic eruptions result in ash being dispersed over wide areas around the eruption site. And depending on the chemistry of the magma from which it erupted, this ash will be contain varying amounts of soil nutrients. While the most abundant elements in magma are silica and oxygen, eruptions also result in the release of water, carbon dioxide (CO²), sulfur dioxide (SO²), hydrogen sulfide (H²S), and hydrogen chloride (HCl), amongst others.

In addition, eruptions release bits of rock such as potolivine, pyroxene, amphibole, and feldspar, which are in turn rich in iron, magnesium, and potassium. As a result, regions that have large deposits of volcanic soil (i.e. mountain slopes and valleys near eruption sites) are quite fertile. For example, most of Italy has poor soils that consist of limestone rock.

But in the regions around Naples (the site of Mt. Vesuvius), there are fertile stretches of land that were created by volcanic eruptions that took place 35,000 and 12,000 years ago. The soil in this region is rich because volcanic eruption deposit the necessary minerals, which are then weathered and broken down by rain. Once absorbed into the soil, they become a steady supply of nutrients for plant life.

Hawaii is another location where volcanism led to rich soil, which in turn allowed for the emergence of thriving agricultural communities. Between the 15th and 18th centuries on the islands of Kauai, O'ahu and Molokai, the cultivation of crops like taros and sweet potatoes allowed for the rise of powerful chiefdoms and the flowering of the culture we associate with Hawaii today.

Volcanic Land Formations:

In addition to scattering ash over large areas of land, volcanoes also push material to the surface that can result in the formation of new islands. For example, the entire Hawaiian chain of islands was created by the constant eruptions of a single volcanic hot spot. Over hundreds of thousands of years, these volcanoes breached the surface of the ocean becoming habitable islands, and rest stops during long sea journeys.

This is the case all across the Pacific, were island chains such as Micronesia, the Ryukyu Islands (between Taiwan and Japan), the Aleutian Islands (off the coast of Alaska), the Mariana Islands, and Bismark Archipelago were all formed along arcs that are parallel and close to a boundary between two converging tectonic plates.

Much the same is true of the Mediterranean. Along the Hellenic Arc (in the eastern Mediterranean), volcanic eruptions led to the creation of the Ionian Islands, Cyprus and Crete. The nearby South Aegean Arc meanwhile led to the formation of Aegina, Methana, Milos, Santorini and Kolumbo, and Kos, Nisyros and Yali. And in the Caribbean, volcanic activity led to the creation of the Antilles archipelago.

Where these islands formed, unique species of plants and animals evolved into new forms on these islands, creating balanced ecosystems and leading to new levels of biodiversity.

Volcanic Minerals and Stones:

Another benefits to volcanoes are the precious gems, minerals and building materials that eruptions make available. For instance, stones like pumice volcanic ash and perlite (volcanic glass) are all mined for various commercial uses. These include acting as abrasives in soaps and household cleaners. Volcanic ash and pumice are also used as a light-weight aggregate for making cement.

The finest grades of these volcanic rocks are used in metal polishes and for woodworking. Crushed and ground pumice are also used for loose-fill insulation, filter aids, poultry litter, soil conditioner, sweeping compound, insecticide carrier, and blacktop highway dressing.

Perlite is also used as an aggregate in plaster, since it expands rapidly when heated. In precast walls, it too is used as an aggregate in concrete. Crushed basalt and diasbase are also used for road metal, railroad ballast, roofing granules, or as protective arrangements for shorelines (riprap). High-density basalt and diabase aggregate are used in the concrete shields of nuclear reactors.

Hardened volcanic ash (called tuff) makes an especially strong, lightweight building material. The ancient Romans combined tuff and lime to make a strong, lightweight concrete for walls, and buildings. The roof of the Pantheon in Rome is made of this very type of concrete because it's so lightweight.

Precious metals that are often found in volcanoes include sulfur, zinc, silver, copper, gold, and uranium. These metals have a wide range of uses in modern economies, ranging from fine metalwork, machinery and electronics to nuclear power, research and medicine. Precious stones and minerals that are found in volcanoes include opals, obsidian, fire agate, flourite, gypsum, onyx, hematite, and others.

Global Cooling:

Volcanoes also play a vital role in periodically cooling off the planet. When volcanic ash and compounds like sulfur dioxide are released into the atmosphere, it can reflect some of the Sun's rays back into space, thereby reducing the amount of heat energy absorbed by the atmosphere. This process, known as "global dimming", therefore has a cooling effect on the planet.

The link between volcanic eruptions and global cooling has been the subject of scientific study for decades. In that time, several dips have been observed in global temperatures after large eruptions. And though most ash clouds dissipate quickly, the occasional prolonged period of cooler temperatures have been traced to particularly large eruptions.

Because of this well-established link, some scientists have recommended that sulfur dioxide and other be released into the atmosphere in order to combat global warming, a process which is known as ecological engineering.

Hot Springs And Geothermal Energy:

Another benefit of volcanism comes in the form of geothermal fields, which is an area of the Earth characterized by a relatively high heat flow. These fields, which are the result of present, or fairly recent magmatic activity, come in two forms. Low temperature fields (20-100°C) are due to hot rock below active faults, while high temperature fields (above 100°C) are associated with active volcanism.

Geothermal fields often create hot springs, geysers and boiling mud pools, which are often a popular destination for tourists. But they can also be harnessed for geothermal energy, a form of carbon-neutral power where pipes are placed in the Earth and channel steam upwards to turn turbines and generate electricity.

In countries like Kenya, Iceland, New Zealand, the Phillipines, Costa Rica and El Salvador, geothermal power is responsible for providing a significant portion of the country's power supply – ranging from 14% in Costa Rica to 51% in Kenya. In all cases, this is due to the countries being in and around active volcanic regions that allow for the presence of abundant geothermal fields.

Outgassing and Atmospheric Formation:

But by far, the most beneficial aspect of volcanoes is the role they play in the formation of a planet's atmosphere. In short, Earth's atmosphere began to form after its formation 4.6 billion eyars ago, when volcanic outgassing led to the creation of gases stored in the Earth's interior to collect around the surface of the planet. Initially, this atmosphere consisted of hydrogen sulfide, methane, and 10 to 200 times as much carbon dioxide as today's atmosphere.

After about half a billion years, Earth's surface cooled and solidified enough for water to collect on it. At this point, the atmosphere shifted to one composed of water vapor, carbon dioxide and ammonia (NH³). Much of the carbon dioxide dissolved into the oceans, where cyanobacteria developed to consume it and release oxygen as a byproduct. Meanwhile, the ammonia began to be broken down by photolysis, releasing the hydrogen into space and leaving the nitrogen behind.

Another key role played by volcanism occurred 2.5 billion years ago, during the boundary between the Archaean and Proterozoic Eras. It was at this point that oxygen began to appear in our oxygen due to photosynthesis – which is referred to asthe "Great Oxidation Event". However, according to recent geological studies, biomarkers indicate that oxygen-producing cyanobacteria were releasing oxygen at the same levels there are today. In short, the oxygen being produced had to be going somewhere for it not to appear in the atmosphere.

The lack of terrestrial volcanoes is believed to be responsible. During the Archaean Era, there were only submarine volcanoes, which had the effect of scrubbing oxygen from the atmosphere, binding it into oxygen containing minerals. By the Archaean/Proterozoic boundary, stabilized continental land masses arose, leading to terrestrial volcanoes. From this point onward, markers show that oxygen began appearing in the atmosphere.

Volcanism also plays a vital role in the atmospheres of other planets. Mercury's thin exosphere of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor is due in part of volcanism, which periodically replenishes it. Venus' incredibly dense atmosphere is also believed to be periodically replenished by volcanoes on its surface.

And Io, Jupiter's volcanically active moon, has an extremely tenuous atmosphere of sulfur dioxide (SO²), sulfur monoxide (SO), sodium chloride (NaCl), sulfur monoxide (SO), atomic sulfur (S) and oxygen (O). All of these gases are provided and replenished by the many hundreds of volcanoes situated across the moon's surface.

As you can see, volcanoes are actually a pretty creative force when all is said and done. In fact, us terrestrial organisms depend on them for everything from the air we breathe, to the rich soil that produces our food, to the geological activity that gives rise to terrestrial renewal and biological diversity.


Volcanoes tied to shifts in Earth's climate over millions of years

Volcanoes tied to shifts in Earth's climate over millions of years Science & Technology World Website


Volcano Licancabur, an active volcano in the Andean continental volcanic arc on the Chile-Bolivia border, looms above flamingos in a nearby lake.

A new study in the April 22 edition of Science reveals that volcanic activity associated with the plate-tectonic movement of continents may be responsible for climatic shifts from hot to cold over tens and hundreds of millions of years throughout much of Earth's history.

The study, led by researchers at The University of Texas at Austin Jackson School of Geosciences, addresses why the Earth has fluctuated from periods when the planet was covered in ice to times when even the polar regions were ice-free.

The study explores very long-term shifts in Earth's baseline climate, not short-term or human-induced climate change.

Lead researcher Ryan McKenzie said the team found that periods when volcanoes along continental arcs were more active coincided with warmer, or greenhouse, conditions over the past 720 million years. Conversely, periods when continental arc volcanos were less active coincided with colder, or icehouse, conditions.

Continental volcanic arc systems such as the Andes Mountains are created at active continental margins where two tectonic plates meet and the oceanic plate descends under the continental plate, forming a subduction zone. When this happens, magma mixes with carbon trapped in the Earth's crust and releases carbon dioxide (CO2) gas into the atmosphere when volcanoes in the system erupt.

"Continental arc systems are plumbed through the Earth's crust and they tend to interact with carbon reservoir rock preserved beneath the surface," said McKenzie, who began the work as a postdoctoral researcher at the Jackson School and finished the study at Yale University.

Scientist have long known that the amount of carbon dioxide in the atmosphere influences the Earth's climate, McKenzie said. The unanswered question is what caused the fluctuations in CO2 observed in the geologic record. Other theories have suggested that geological forces such as mountain building have, at different times in the planet's history, introduced large amounts of new material to the Earth's surface, and weathering of that material has drawn CO2 out of the atmosphere. The new study points to the amount of CO2 being released into the atmosphere, rather than the amount removed from it, as the primary driver of Earth's climate.

Using nearly 200 published studies and their own fieldwork and data, researchers created a global database to reconstruct the volcanic history of continental margins over the past 720 million years.

"We studied sedimentary basins next to former volcanic arcs, which were eroded away over hundreds of millions of years," said co-author Brian Horton, a professor in the Jackson School's Department of Geological Sciences. "The distinguishing part of our study is that we looked at a very long geologic record - 720 million years - through multiple greenhouse-icehouse events."

Specifically, researchers looked at the uranium-lead crystallization ages of the mineral zircon, which is largely created during continental volcanic arc activity. Zircon is less common in other types of volcanic settings, such as hot spots like Hawaii or island arc volcanoes such as the Marianas, so the mineral can be used to track continental arc volcanism. For the study, they looked at data for roughly 120,000 zircon grains from thousands of samples across the globe.

"We're looking at changes in zircon production on various continents throughout Earth's history and seeing how the changes correspond with the various icehouse and greenhouse transitions," McKenzie said. "Ultimately, we find that during intervals of high zircon production we have greenhouse conditions, and as zircon production diminishes, we see a shift into our icehouse conditions."

The cooler icehouse periods tended to correlate with the assembly of the Earth's supercontinents, which was a time of diminished continental volcanism, Horton said. The warmer greenhouse periods correlated with continental breakup, a time of enhanced continental volcanism.

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