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Geoscience hot topics – Part I: The Earth’s past and its origin

Geoscience hot topics – Part I: The Earth’s past and its origin

What are the most interesting, cutting-edge and compelling research topics within the scientific areas represented in the EGU divisions? Ground-breaking and innovative research features yearly at our annual General Assembly, but what are the overarching ideas and big research questions that still remain unanswered? We spoke to some of our division presidents and canvased their thoughts on what the current Earth, ocean and planetary hot topics will be.

There are too many to fit in a single post so we’ve brought some of them together in a series of posts which will tackle three main areas: the Earth’s past and its origin, the Earth as it is now and what its future looks like, while the final post of the series will explore where our understanding of the Earth and its structure is still lacking. We’d love to know what the opinions of the readers of GeoLog are on this topic too, so we welcome and encourage lively discussion in the comment section!

 

The Earth’s past and its origin

Rephrasing the famous sentence by James Hutton, i.e. the present is the key to the past, we can even say that the past is the key to the future – a better understanding of past Earth processes can help understand why and how our planet evolved to have oceans, an atmosphere, a planetary magnetic field as well as the ability to sustain life. Not only that, a greater understanding of the Earth’s past can aid in finding solutions to present day problems. A strong interdisciplinary research effort is required to delve into the Earth’s past and that makes it one of the most important geoscience hot topics, albeit very broad.

Life on Earth and the physical environment

Zircons in rocks from Jack Hills in Western Australia provide evidence of oceans 4.4 b.y. ago and of conditions that may have haboured life. The remarkable thing is that these rocks are 300 million years older than the 3.8 billion year old rocks from Greenland, which were thought to hold the oldest evidence for life on Earth, until now.

Image by Robert Simmon, based on data from the University of Maryland’s Global Land Cover Facility

Jack Hills, Western Australia. Image by Robert Simmon, based on data from the University of Maryland’s Global Land Cover Facility

These findings are no doubt very exciting, but they also go hand in hand with gaining a greater understanding about the physical environment in which these early life forms evolved. According to Helmut Weissert, President of the Stratigraphy, Sedimentology and Palaeontology Division (SSP), understanding the co-evolution of life and the physical environment in Earth’s history is one of the biggest challenges for current and future scientists. Understanding past changes of the System Earth will facilitate the evaluation of man’s role as a major geological agent affecting global material and geochemical cycles in the Anthropocene.

The work of scientists in the SSP fields on understanding how the evolution of life was affected by major climatic perturbations is particularly timely, given the ongoing debate as to whether the presence of humans on Earth is potentially driving a sixth mass extinction event. Not only that, a big research question still unanswered is how did catastrophic events during the Earth’s history also affect evolutionary rates?

Developing new models and tools which might aid investigation in these areas is at the forefront of challenges to come, along with a greater interaction between related disciplines, for instance (but of course, not limited to!) the geosciences and genetics.

A changing inner Earth

The Earth’s magnetic field is one of ingredients for the presence of life on Earth, because it screens most of the cosmic rays that otherwise would penetrate in major quantities into the atmosphere and reach the surface, being dangerous for human health.

“A recent discovery is that the absence of magnetic field would cause serious damages not only to humans through a significant increase of cancer cases, but also to plants”, say Angelo De Santis, President of the Earth Magnetism and Rock Physics Division (EMRP), “implying that geomagnetic field reversals characterised by times with very low intensity of the field, would have serious implications for life on the planet”.

Another way to understand this aspect would be to have a look at the past. One of the (many) tools which can be used to understand what our planet might have looked like in its infancy is palaeomagnetism. This is especially true when it comes to one of the biggest conundrums of the Precambrian: when did plate tectonics, as we understand them now, start?

That there was perhaps some form of plate motions in the Earth’s early life is likely, but exactly what the style of those plate motions were during the Precambrian is still highly debated. Palaeomagnetic directions measured over time are used to estimate lateral plate motions associated with modern day style plate tectonics involving subduction. If similar plate motions can be identified in rocks younger than 500Ma then they might support lateral plate motions early in the Earth’s history. This, says Angelo De Santis, is one of the most exciting areas of research within Earth magnetism.

 Earth Magnetic Field Declination from 1590 to 1990 by U.S. Geological Survey (USGS). Licensed under Public Domain via Wikimedia Commons . Click on the image to see how the field changes over time.

Earth Magnetic Field Declination from 1590 to 1990 by U.S. Geological Survey (USGS). Licensed under Public Domain via Wikimedia Commons . Click on the image to see how the field changes over time.

Not only that, studying the strength of the geomagnetic field (which is generated in the liquid outer core by a process known as the geodynamo) and how it changes over different time scales can give us information about the early inner structure of the planet. For instance, news of a new date for the age of the formation of the inner core, after researches identified the sharpest increase in the strength of the Earth’s magnetic field, hit the headlines recently. The findings imply that maybe some of the views Earth scientists hold about the core of the Earth might need to be revised!

Which leads us onto secular variation – the study of how the geomagnetic field changes, not only in strength but also in direction – because if the early core is different to how it was previously thought, is the understanding of secular variation also affected? The implications are far reaching, but a highlight, according to Angelo De Santis, has to be how the findings might affect how periods of large change (more commonly known as geomagnetic reversals) are understood. Therefore, it is key that the evolution of the geodynamo is better understood, so that scientists might be able to assess the possibility of an imminent excursion (a large change of the field, but not a permanent flip of the direction) or reversal.

From the inner Earth to the surface

If studying the inner depths of the Earth in the past might give us clues about the present and future of the planet’s core, so to on and above the surface the past can be the key to the future.

Geological time spiral" by United States Geological Survey - Graham, Joseph, Newman, William, and Stacy, John, 2008, The geologic time spiral—A path to the past (ver. 1.1): U.S. Geological Survey General Information Product 58, poster, 1 sheet. Available online at http://pubs.usgs.gov/gip/2008/58/. Licensed under Public Domain via Commons.

Geological time spiral by United States Geological Survey – Graham, Joseph, Newman, William, and Stacy, John, 2008, The geologic time spiral—A path to the past (ver. 1.1): U.S. Geological Survey General Information Product 58, poster, 1 sheet. Available online at http://pubs.usgs.gov/gip/2008/58/. Licensed under Public Domain via Commons.

Present day climate change is a given, but predictions of how the face of the Earth might change as a result remain difficult to make while, at the same time, its consequences are not yet fully understood. Studying the climate of the past and how the biosphere, oceans and the Earth’s surface (including erosion and weathering processes), responded to abrupt and potentially damaging changes in Earth’s past climate provides a starting point to make forecasts about the future.

“A better time resolution of geological archives means we are able to further test present day climate, weathering and ocean models,” says SSP President Helmut Weissert.

And so, not only does the past tell us where we come from and how the Earth became the only planet in our Solar System capable of sustain complex forms of life, a better understanding of its origins and past behaviour might just help us improve the future too.

Next time, in the Geosciences hot topics short series, we’ll be looking at our understanding of the Earth as we know it now and how we might be able to adapt to the future. The question of how we develop the needs for an ever growing population in a way that is sustainable opens up exciting research avenues in the EMRP and SSP Divisions, as well as the Energy, Resources and the Environment (ERE), Seismology (SM) and Earth and Space Science Informatics (ESSI) Divisions.

Imaggeo on Mondays: What a thin section has to say about the deformation of the Zagros Mountains

Imaggeo on Mondays: What a thin section has to say about the deformation of the Zagros Mountains

The impressive Zagros Orogeny, as seen from a bird’s-eye view, has featured on Imaggeo on Monday’s blog posts a few times recently. From its fluvial dissection features, through to a false colour LANDSAT 7 image which reveals a velociraptor hiding among fold and thrusts, we’ve looked at the broad scale structures which shape the Zagros mountains. This week, the scale changes entirely: we zoom right into the fabric of the Zagros Mountains rocks, as shown by the minerals in a thin section. Despite the close-up and small-scale view thin sections offer, they can still reveal huge amounts of information about the past history of rocks.

The thin section image above, taken by Amirhossein Mojtahedzadeh, a member of the Geological Society of Iran, is from the northwestern part of the Zagros mountain belt, which spans Kurdistan (in northwester Iran). Here, the mountains have suffered multiple stages of metamorphism and deformation, as evidenced by the large twinned plagioclase (the stripped white and black mineral which dominates the image) in the centre of the view. Plagiocalse is a common rock-forming mineral of the silicate family. Amongst their many properties, plagioclase crystals commonly form twins, which essentially means that a single crystal of a mineral has two or more parts in which the crystal lattice is differently orientated (which is explained in full detail in this great blog post by former EGU network bloggers, Between a Rock and a Hard Place). This property of plagioclases is an important tool in petrological analysis as it usually results from a change in the conditions while the mineral is forming, hinting at larger scale changes in the rock‘s environment, such as an increase in the local environments pressure or temperature, for example.

The rock in the thin section above, is a metamorphosed olivine gabbro – typically formed in igneous environments – except that the plagioclases reveal tell-tale signs that this particular specimen has been reheated or buried, perhaps even both, after if formed. Local strain in the rocks results in the twinned crystals having a lenticular shape. Plastic deformation (meaning the crystal will never go back to the shape it was originally) driven by situations of intense temperature and pressure, causes atomic layers in minerals to slide past each other without friction and thus changes the orientation of twins. Whilst studying the rock, Amirhossein found that sometimes these conditions made elongated aggregates and led to the minerals gaining a new crystal structure.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

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Edit (26/10/2015): Following comments by Graham Cunningham on Facebook, this text was improved by substituting silicon family to silicate family in the sentence: Plagiocalse is a common rock-forming mineral of the silicate family.

 

Imaggeo on Mondays: Mount Etna

Imaggeo on Mondays: Mount Etna

In this week’s Imaggeo on Monday’s image an almost Martian looking landscape, with ombre coloured soils, gives way to gently rolling hills, covered in luscious woods and vegetation. Were it not for the trees in the distance, you would be forgiven for thinking this image had been captured by a Mars rover. In truth, it is an entirely more earthly landscape: welcome to the slopes of Mt. Etna! Keep on reading as Alicia Mourgán, a researcher at the University of València, gives an overview of the origin of the richly fertile soils and climate of Europe’s tallest active volcano.

Mount Etna is associated with the subduction of the African Plate under the Eurasian Plate. A number of theories have been proposed to explain Etna’s location and eruptive history: rifting processes, a hot spot, and the intersection of structural breaks in the crust. Scientists are still debating which best fits their data, and are using a variety of methods to build a better image of the Earth’s crust underneath the volcano.

The soil around the volcano is very rich in minerals, owing to its volcanic origin. It is composed of a number of eruptive materials of different ages, including ash, sand and desintegrated lava (from one or more flows). Volcanic rocks make some of the best soils on Earth: not only are they formed of a wide variety of common elements, these readily separate into their elemental forms.

In the Etna region there are substantial differences in climate, not only compared to the rest of Sicily, but also from one area of the volcano to another. This is due to the fact that the Etna region has semi-circular shape, spread from north to south-west. This characteristic allows for different environments to be formed each with its own microclimate, benefiting from different exposure and changing proximity to the sea. Altitude in the Etna region varies between 450 m and 1100m above sea level. This factor is the main reason for the temperature changes between the day and night and also across seasons.

Compared to the rest of Sicily, Etna is pretty wet too. The highest levels of precipitation are recorded on the east slopes of the volcano. Rain can be practically absent over the summer, but precipitation can also be very high during the autumn/winter period.

By Alicia Morugán, University de València, València, Spain

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

A journey into the Cordon Caulle volcano

A journey into the Cordon Caulle volcano

There is no escaping the fact that one of the perks of being an Earth scientist is the opportunity to visit incredible places while on field work. There is also no doubt that, geologist or not, walking on an active volcano is awe inspiring. Maybe you’ve had the experience of doing so yourself (if so, share your story with us in the comments section, we’d love to hear from you!), but if you haven’t then perhaps this post by Fabian Wadsworth, a volcanology PhD student at the Ludwig-Maximillian Universitat of Munich, Germany and part of the VUELCO project, might give you a feel for what it is like. In the post, Fabian describes his experience of journeying into the Cordon Caulle volcano, in Chile. A regular hiker of the German Alps, Fabian described the difference between climbing the impressive, but well-established trails of the Bavarian mountains to his trip to Chile: “a volcano, is dynamic on a large scale and provides little comfort at all. Hiking in active volcanic landscapes is, for me, more vivid and awakening for this reason.”

Ian Schipper with Jon Castro watching the mouth of the volcano churning out volcanic ash. Image Credit: Dr. Hugh Tuffen

Ian Schipper with Jon Castro watching the mouth of the volcano churning out volcanic ash. Image Credit: Dr. Hugh Tuffen

Dr. Hugh Tuffen, Dr. Ian Schipper and Prof. Jon Castro are volcanologists who study how magmas move, flow and explode on their way up to and over the Earth’s surface. They invited me to join them to Cordon Caulle in January 2014, just two years after it stopped erupting explosively in 2012. This team of researchers had been there in 2011 and in 2012 when it was most vigorously exploding and this post combines photographic reflections on their experience and some from my trip to give you a view of this place and the hike that led us into the volcano’s mouth.

This volcano is unique. It is a type of volcano that produces vast quantities of volcanic glass: obsidian. As well as erupting a huge volcanic cloud, typical of many eruptions, it slowly pushed out a dark tongue of obsidian that was hot enough to squeeze at glacial rates down and away from the source. This kind of eruption is rare and Cordon Caulle is the only time in history that such a phenomenon has been witnessed and studied. Scientists are working to understand how the region can be blanketed by volcanic ash – the result of massive explosions – while this seemingly gentle tongue is pushed out at the same time. In this way, obsidian is one of the most interesting materials to volcanologists and it draws us from all over the world to hike in these wonder-places.

From Puerto Monnt we travelled the 125 km northeast deep into the Andes. The hike to the volcano begins with a long journey through forest up to the highland plateaus. In 2012 this forested land was densely covered in ash from the volcano, Hugh told me, but by 2014 had fully recovered its lush green. From the plateau, the Andes unfold before you and make the many hours hiking feel insignificant. We carried our equipment as well as water, food and sleeping gear ready for a week or more spent in the shadow of the lava. In 2012, the noise of the eruption was intense and could be heard for kilometres around. By 2014-2015, all was quiet except for the buzzing of horseflies and the occasional creek from the heavy glass lava that still crumbled its way over the sand.

The forest land on the hike up in 2012. Hugh remembers the ash filling his hair and covering everything. Image Credit: Dr. Hugh Tuffen

The forest land on the hike up in 2012. Hugh remembers the ash filling his hair and covering everything. Image Credit: Dr. Hugh Tuffen

All around are the dunes of the highland plateaus, ribbed with rainwater gullies and patches of ice, which quench the thirst of hardworking volcanologists.

The dunes of the highland plateaus light up in the low sun. Image Credit: Dr. Hugh Tuffen

The dunes of the highland plateaus light up in the low sun. Image Credit: Dr. Hugh Tuffen

Walking from site to site is hard because the ash-laden sand is soft and sometimes you sink deep. Boots fill with pebble-sized volcanic shards that litter the ground from the last eruption. The distances are also deceptive. The lava, this slow-moving lava flow of glass, is almost forty meters high and many kilometres wide. We made basecamp at one end of the lava and each day hiked to places of interest, sometimes for hours, around the plateaus.

Hugh returned in 2015 yet again with Mike James and student Nathan Magnall and walked between slivers of cloud and tongues of glassy lava. Image Credit: Dr. Hugh Tuffen

Hugh returned in 2015 yet again with Mike James and student Nathan Magnall and walked between slivers of cloud and tongues of glassy lava. Image Credit: Dr. Hugh Tuffen

Starting before dawn, we took one day to set off for a place no one has seen before. We wanted to climb into the mouth of the volcano; into the vent from where the lava was being pushed out back in 2011 and 2012. No one has been into such a place before – the source of obsidian – and we thought that some of the observations we could make would hold a key to the puzzle of these eruptions. We hiked for hours around the great lava flow and to the back side of the vent area. We put on our gas masks to filter some of the still-circulating toxic volcanic gases and particles and we pulled our hats down against the fierce sun. We climbed the cone to the top and peered down into the vent area itself. From that vantage point we circled down the cone’s rim and into the vent proper. From there, gazing back up at the inner walls of the volcano, Hugh, Jon and Ian remembered watched this area explode and writhe just a few years before at the height of eruption. With an uneasy feeling, we set about learning what we could from the rocks and glass at the source of obsidian on our Earth’s surface.

Snatching our hard-won science, we returned to camp only after dark, hungry and thirsty and shared the small celebratory whisky ration we had brought with us. This day, inside the volcano, will remain among the most vivid in my life. And now, back in Munich, I can readily recall the sulfur smell and shine of the glass in that place.

Hugh, Ian and Jon will no doubt continue to return to this enigmatic place to learn more each year and will listen out for the next time obsidian erupts. Nathan Magnall has recently embarked on a PhD project focused on unveiling more of the mysteries of this place and Tuppence Stone, Toby Strong and Christiaan Munoz Salas, who joined Hugh in January 2015, filmed for the forthcoming BBC2 Patagonia series. You can also watch Hugh talk about Cordon Caulle in the video below too – skip to minute 13:00.

The poetry of the place should surely draw people from all disciplines to walk on those new stones – something I emphatically encourage you to do.

By Fabian Wadsworth, PhD Student Ludwig-Maximillian Universitat.

This post was originally posted on the Yetirama Blog. For the original post, please follow this link. We are very thankful to Dr. Hugh Tuffen for the use of his images in this post.

 

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