Geology – Australian Science

What do Mars and Australia have in common?

Markus — Tue, 11 Jun 2013 00:29:45 +0000

If you’re expecting a punchline to that title, then guess again. It’s no joke. Surprisingly, Australia shares some remarkably similar geology to our neighbouring planet. Specifically the Red Centre, the arid heart of Australia, is the most Mars-like place on Earth!

It’s possible that people may have mused on the similarities already. After all, with its strikingly rich colours, the Red Centre (more often known as the Outback) certainly looks like few other places on Earth. Without any vegetation, the colour of the soil and rocks in the region could easily resemble Mars in places. But evidently, this resemblance is more than just skin deep. The clue that lead to this fascinating realisation? Another of Australia’s most beautiful and iconic of things – opals.

A view from the top of Uluru, showing it’s distinctive red colour. Credit: Binarysequence/Wikimedia Commons

Patrice Rey at the University of Sydney’s School of Geosciences was investigating how opals formed. It may be surprising to learn that opals are found in few other places on Earth, with roughly 90% of all opals worldwide having originated in Australian mines. Beautiful and sought after, there’s been a lot of mystery behind opals for a long time – specifically about how they form, why they’re found at such shallow depths under the Australian soil, and why they’re found nearly nowhere else on Earth.

The story of these beautiful sparkly gemstones, it turns out, began around 100 million years ago. At the time, most of central Australia was covered by the Eromanga Sea. In times past, this huge epicontinental (inland) sea covered what is now known as the Eromanga Basin – spanning an area of one million square kilometres and reaching into much of what is now Queensland, the Northern territories, South Australia and New South Wales.

During the Cretaceous period, when dinosaurs still ruled our planet, this sea would have been teeming with prehistoric life. But much like the dinosaurs, the Eromanga Sea was doomed. Around 100 million years ago, the climate of Earth began to change and the sea began to dry out. The sea dried out rapidly on geological timescales, to cover a much smaller area. The result was that the chemistry of the surrounding rocks began to change.

As the Eromanga Sea dried out, pyrite minerals in the surrounding rocks began to release sulfuric acid, causing acid weathering on a huge scale – quite possibly the largest Earth has ever seen. The opaline silica which was created in the Australian rocks during this process would later go on to form into opals. But the big clue is the acid weathering – we only know of one other place in the Solar System where this has happened in the past. Planet Mars.

While the predicament of prehistoric Australia is, as far as we know, unique on Earth, Mars actually shares a lot in common with this event. Except on Mars, we believe that the drying out of seas happened on a global scale. Hints of this were detected in 2008, when NASA’s twin Mars rovers, Spirit and Opportunity, detected several telltale clues in the Martian soil.

The surface of Mars was found to hold opaline silica, iron oxides, and certain types of clay. All of these clues led areologists* to conclude that the surface of Mars had been subject to huge amounts of acid weathering. The exact same type of acid weathering which Rey and his fellow researchers have now discovered to have happened in Australia!

An opal doublet from Andamooka, South Australia. Credit: CRPeters/Wikimedia Commons

If you’re thinking that this means that there may be Martian opals waiting to be discovered somewhere on the planet next door, it’s hard to say. But it’s certainly a possibility! There is, however, one final step in the formation of opals. The opaline silica which was found on Mars is not yet true opal. In Australia, the surrounding rock has an impressive capability to neutralise acid. This means that after the ground in Australia became riddled with opaline silica, the surrounding conditions quickly went from acid to alkaline. When this happens before the silica trapped in rock cavities dehydrates and solidifies – voila! Opals! Of course, there’s a good chance that Mars may be home to some kinds of rock which can also neutralise acid the same way.

So only time will tell. Perhaps someday in the future, Martian colonists may be using Mars opals to create the first ever jewellery made elsewhere in the Solar System!

*An areologist studies the geology of Mars, seeing as technically the “geo” in geology refers to planet Earth.

Could there be opals hiding under the Martian soil? Credit: NASA/JPL

Cite this article:
Hammonds M (2013-06-11 00:29:45). What do Mars and Australia have in common?. Australian Science. Retrieved: May 07, 2024, from http://australianscience.com.au/geology/what-do-mars-and-australia-have-in-common/

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The post What do Mars and Australia have in common? appeared first on Australian Science.

Weekly Science Picks

Magdeline.L — Sun, 25 Nov 2012 00:15:18 +0000

The midlife crisis is more complicated than first thought. It might be time to stop blaming troubled marriages and feeling obsolete in a sea of younger colleagues. A study published in the Proceedings of the Natural Academy of Sciences has revealed that chimpanzees and orangutans also experience a midlife crisis.

Having a midlife crisis may not just be the result of a troubled marriage or the thought that life may be halfway over. It might be part of primate biology. That’s right, hardwired into us.

Economist Andrew Oswald told ABC Science that it might be beneficial.

“Maybe discontent lights a fire under people, causing them to achieve more for themselves and their family.”

A shiny new red sports car might just indeed lead to better things.

Danielle Spencer runs a science club at Mitchelton State School in Queensland and explored where gender stereotypes in science began. Where does the perception that men do the “hard” sciences and women do the “soft” sciences come from? A group of 45 primary school students were surveyed and it was found that a majority of students thought that science was accessible to both genders.

When asked why there are more men than women in engineering roles, the students responded with gender based answers like “Girls like dancing and other jobs.” and “Women are more suited to caring and developing jobs like childcare and nursing.”. There was no response that challenging this observation. This was despite 75% of the group thinking that science was accessible to them. It is disheartening to hear.

Students were asked whether their science club should be split into a boys only and girls only science club, there was overwhelming support for a combined science club. There was an appreciation and acknowledgement that irrespective of gender, everyone had a valuable contribution. At the moment this cohort of students believe that science is something that everyone can do. The question remains though, how do we get adults to believe this?

As this week drew to a close, attention focused on NASA’s Jet Propulsion Laboratory in Pasadena, California. A story broke at NPR reporting that the Curiosity Rover may have found some exciting news. Project Scientist at the Mars Science Laboratory, John Grotzinger was quoted to saying:

“We’re getting data from SAM as we sit here and speak, and the data looks really interesting.”

SAM, the Sample Analysis at Mars is a miniaturised chemistry lab. On board is a Gas Chromatograph, Quadrupole Mass Spectrometer, Tunable Laser Spectrometer as well as sample processing systems that allow heating and chemically treating samples. Normally these instruments would fill the space in a laboratory but on Curiosity it’s around the size of a microwave. SAM is being used to collect information about the past and present chemistry of Mars. As well as this SAM is also identifying organic and inorganic chemical molecules known to be important to life on Earth.

So what has SAM found? Nothing has been confirmed but it does sound like there is something especially when Grotzinger says:

“This data is gonna be one for the history books.”

We will have to wait at least several weeks before NASA makes an announcement.

New Zealand’s volcano, Mount Tongariro made it into this week’s news with an eruption on Wednesday. Luckily there have been no reports of damage or injuries. However, a group of travellers and journalists hiking at the time witnessed and filmed the eruption.

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Breaking plates

Markus — Wed, 24 Oct 2012 00:09:21 +0000

What do Australia and India have in common? The answer is that they both share one of Earth’s tectonic plates – the drifting eggshell-like pieces of Earth’s crust, on which all of our planet’s continents sit. However, the Indo-Australian Plate is a slightly unusual one, and the two countries may not share it for much longer. Recent Earthquakes beneath the Indian Ocean suggest that this plate may be in the process of breaking in two.

We generally think of the surface of our planet as being fixed and unchanging. The reality though, is that this isn’t true. Earth’s continents and the tectonic plates which make them up are not fixed at all, drifting slowly across the planet’s surface. For instance, as you’re reading this, most of Africa is moving slowly to the North West and quietly tearing the beginnings of a new ocean into Earth’s surface. Meanwhile, Hawaii is moving at a speed of about 7cm per year which is about as fast as your fingernails are growing.

Of course, these movements are tiny, compared to the size of the Earth and its continents, but they still cause pressure to build up in Earth’s surface. Sometimes, seemingly without warning, that pressure continues to build up and– SNAP! Something in Earth’s crust cracks or ruptures. This jostles the plates and can cause earthquakes which rattle entire countries. Any places situated at the edges of tectonic plates are particularly prone to earthquake activity, with California and Japan being high profile examples. With enough quakes, however, dramatic changes can happen in Earth’s crust. On rare occasions, larger tectonic plates can sometimes break apart into smaller ones – and that’s exactly what’s happening somewhere beneath the Indian Ocean right now.

Breaking point – where the Indo-Australian plate is starting to rupture and split

April 11 this year saw two massive earthquakes strike west of Indonesia in quick succession, measuring 8.7 and 8.2 on the Richter scale. The result was a dramatic quadruple fault rupture in Earth’s crust (a rare event which is more or less exactly what it sounds like!) which caused shockwaves to reverberate around the whole planet. Around a week later quakes occurred across the world as the whole planet shivered in response.

Geologists, alarmed by what could have caused such a major event, took to analysing the quake. What they found was remarkable. Within roughly 160 seconds, four fault lines (existing fractures in the rock) tore apart under pressure. Remarkably though, this wasn’t at a plate boundary where this kind of activity is expected. It was right in the middle of the Indo-Australian plate. To the geologists looking at this data, this was like a smoking gun. A telltale sign that, as many had suspected, this particular tectonic plate is starting to fracture and split into two.

The Indo-Australian tectonic plate is already a bit of an oddity, being a rather thin and unusual shape compared with the others. The reason being that it was formed some 43 million years ago when two smaller plates (carrying the landmasses which would eventually become India and Australia) fused together. Since then though, it’s collided with the much more massive Eurasian plate. That collision has already caused enough pressure in Earth’s crust to create the Himalayas, one of the world’s most impressively tall mountain ranges. However, the Indo-Australian plate is still trying to move northwards. The western part of the plate is still pushing against the Himalayas, moving at about 3.7 centimetres per year, but the eastern part, including the entire continent of Australia, is moving at a much faster speed of around 5.6 centimetres per year. This is causing the whole tectonic plate to quite literally buckle, which is the root cause behind all of the quakes in the region over the past decade.

So what does this mean for anyone who happens to be living on that plate? Well, there are not going to be any sudden apocalyptic changes. After all, according to theories, this is not actually a new event – the Indo-Australian plate began to deform around 10 million years ago! Over millions of years, a new tectonic plate boundary will start to form under what is currently the Indian Ocean. This will cause thousands of similarly large earthquakes, but over such a length of time that they won’t be much more regular than they already are for those living around South-East Asia. All the same, planetary scientists are likely to continue watching this region with interest over the coming years.

Satellite view of the Himalayan mountain range – perhaps the most dramatic example of the force with which the Indo-Australian plate is pushing into the Eurasian plate!

Image credits:
Top – NASA Goddard
Middle – Keith Koper/Uni. Utah Seismograph Stations
Bottom – NASA World Wind

Cite this article:
Hammonds M (2012-10-24 00:09:21). Breaking plates. Australian Science. Retrieved: May 07, 2024, from http://australianscience.com.au/news/breaking-plates/

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Where to land Mars Curiosity for the best science? Interview with Marion Anderson, who helped choose the landing site.

Alan Kerlin — Mon, 06 Aug 2012 00:31:54 +0000

Australian geologist Marion Anderson, with a model of Curiosity's predecessor rover Opportunity. Source: The Age

You’ve sunk more than $2 billion into a car-sized rover and you’re ready to send it to explore Mars. But where exactly on Mars do you send it?

Of course you want it and its controllers back here to be able to do the best possible science. So apparently that is exactly what NASA did – consulted the geology scientists of the world.

One of those scientists was Marion Anderson of Melbourne’s Monash University.

In this interview recorded on 2 August 2012, Marion explains to me what went into the selection of Gale Crater as the landing site for the Mars Curiosity rover, what to expect from the rover as it begins to explore the crater after its landing there on Monday 6 August, and why Curiosity is NOT looking for life, despite what many media people are saying (running time 20 mins).

Marion also talks about her role in selecting the landing sites for those other Mars rovers Spirit and Opportunity, and where next after Mars?

If you are interested in learning more about the geology of Mars, I highly recommend the one-hour lecture by Richard Pogge titled The Deserts of Mars from an entire – free – university course in Astrobiology from Ohio State University (also available on iTunes).

In the interview you’ll hear Marion talk about how Mount Sharp in the centre of Gale Crater is actually higher than the surrounding crater walls – some five kilometres high. In this lecture, listen for an explanation why Olympus Mons is the highest volcanic cone in our Solar System, and probably explaining the height of Mount Sharp too.

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