GeoLog

palaeomagnetism

Imaggeo on Mondays: Chilean relics of Earth’s past

Imaggeo on Mondays: Chilean relics of Earth’s past

As Earth’s environment changes, it leaves behind clues used by scientists to paint portraits of the past: scorched timber, water-weathered shores, hardened lava flows. Chile’s Conguillío National Park is teeming with these kind of geologic artifacts; some are only a few years old while others have existed for more than 30 million years. The photographer Anita Di Chiara, a researcher at Lancaster University in the UK, describes how she analyses ancient magnetic field records to learn about Earth’s changing crust.

Llaima Volcano, within the Conguillío National Park in Chile, is in the background of this image with its typical double-hump shape. The lake is called Lago Verde and the trunks sticking out are likely remnants from one of the many seasonal fires that have left their mark on this area (the last one was in 2015).

The lake sits on pyroclastic deposits that erupted from the Llaima Volcano. On these deposits, on the side of the lake, you can even track the geologic record of seasonal lake level changes, as the layers shown here mark the old (higher) level of the lake during heavy winter rains.

The lake also overlaps the Liquiñe-Ofqui Fault, which runs about 1000 kilometers along the North Patagonian Andes. The fault has been responsible for both volcanic and seismic activity in the region since the Oligocene (around 30 million years ago).

I was there as field assistant for Catalina Hernandez Moreno, a geoscientist at Italy’s National Institute of Geophysics and Volcanology, studying ancient magnetic field records imprinted on rocks. We examined the rocks’ magnetised minerals (aligned like a compass needle to the north pole) as a way to measure how fragmented blocks of the Earth’s crust have rotated over time along the fault.

From this fieldwork we were able to examine palaeomagnetic rotation patterns from 98 Oligocene-Pleistocene volcanic sites. Even more, we concluded that the lava flows from the Llaima Volcano’s 1958 eruption would be a suitable site for studying the evolution of the South Atlantic Anomaly, an area within the South Atlantic Ocean where the Earth’s magnetic field is mysteriously weaker than expected.

By Anita Di Chiara, a research technician at the Lancaster Environment Centre in the UK 

References

Hernandez-Moreno, C., Speranza, F., & Di Chiara, A.: Understanding kinematics of intra-arc transcurrent deformation: Paleomagnetic evidence from the Liquiñe-Ofqui fault zone (Chile, 38-41°S), Tectonics, https://doi.org/10.1002/2014TC003622, 2014.

Hernandez-Moreno, C., Speranza, F., & Di Chiara, A.: Paleomagnetic rotation pattern of the southern Chile fore-arc sliver (38°S-42°S): A new tool to evaluate plate locking along subduction zones. Journal of Geophysical Research: Solid Earth, 121(2), https://doi.org/10.1002/2015JB012382, 2016.

Di Chiara, A., Moncinhatto, T., Hernandez Moreno, C., Pavón-Carrasco, F. J., & Trindade, R. I. F.: Paleomagnetic study of an historical lava flow from the Llaima volcano, Chile. Journal of South American Earth Sciences, 77, https://doi.org/10.1016/j.jsames.2017.04.014, 2017.

 

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submittheir 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/.

MinCup: Elevating humble minerals to new heights

MinCup: Elevating humble minerals to new heights

Throughout October and November, the world of (Earth science) Twitter was taken by storm: Day after day, Eddie Dempsey (a lecturer at the University of Hull, and @Tectonictweets for those of you more familair with his Twitter handle) pitted minerals against each other, in a knock out style popular contest. The aim? To see which mineral would eventually be crowned the best of 2017.

Who knew fiery (but good natured) rows could explode among colleagues who felt, strongly, that magnetite is far superior to quartz or plagioclase? The Mineral Cup hashtag (#MinCup) was trending, it was in everyone’s mouth. Who would you vote for today?

What started as a little fun, became a true example of great science communication and how to bring a community of researchers, scattered across the globe, together.

And then Hazel Gibson (former EGU Press Assistant, @iamhazelgibson) came along. She was an active participant in the competition, but also contributed beautiful sketches of every mineral featured, and shared them for all to see by tagging them with the #MinCup hashtag. We all know that a picture is worth more than a thousand words, so when Hazel’s hand drawn sketches where paired with an already rocking contest, it’s impact and reach was truly cemented.

Between them, Eddie and Hazel had managed to elevate the humble mineral to new heights.

Why do minerals matter?

Minerals are hugely underrated. They are often upstaged by the heavy-weights of the geosciences: volcanoes, earthquakes, hurricanes, fossils and melting glaciers (to name but a few).

But they shouldn’t be.

Minerals are the building blocks of all rocks, which in turn, are the foundation of all geology.

Whether you study the processes which govern how rivers form, or ancient magnetic fields, or fossils, chances are your work will, at some stage, involve looking at, studying, or at the very least understanding (some) minerals. Mineralogy 101 (or whatever it’s precise name was at your university) is a rite of passage for any aspiring Earth scientist. I still remember hours spent painstakingly looking down a microscope, drawing and annotating sketches trying to decipher the secrets of the Earth’s ancient past, locked in minerals.

And that’s just the beginning.

Minerals are of huge economic and, therefore societal importance, too. Many minerals are vital ingredients in house-hold products and contribute to the manufacturing processes of many others. Yet, they fail to make headlines and their true significance, often, goes unnoticed.

So, in hopes to further highlight the relevance and importance of minerals, I’ve picked a few of the #MinCup minerals and explained why they (should) matter (to you).

Gypsum

Gypsum will form in lagoons, where ocean waters are high in calcium and sulfate content, and where the water evaporates slowly overtime. In rocks, it is associated with sedimentary beds which can be mined to extract the mineral, but it can also be produced by evaporating water with the right chemical composition.

Gypsum has been used in construction and decoration (in the form of alabaster) since 9000 B.C.  Today, it has a wide variety of common uses. Did you know that many fruit juice companies use gypsum to aid the extraction of the liquid? It is also used in bread and dough mixes as a raising agent. And it’s uses aren’t limited to just the food and drink industry. It is also commonly used as a modelling material for tooth restorations and helps keeps us safe when added to plastic products where it acts as a fire retardant.

Magnetite

Geologically speaking, magnetite holds the clues to understand the Earth’s ancient magnetic field. Credit: Hazel Gibson

Typically, greyish black or black, magnetite is an important iron ore mineral. It occurs in many igneous and volcanic rocks and is the most magnetic of all minerals. For it to form, magma has to cool, slowly, so that the minerals can form and settle out of the magma.

Due to its magnetic nature, it has fascinated human-kind for centuries: it paved the way for the invention of the modern compass.  The iron content in magnetite is higher than its more common cousin haematite, making it very sought after. Iron ore is the source of steel, which is used universally throughout modern infrastructure.

Geologically speaking, magnetite holds the clues to understand the Earth’s ancient magnetic field. As magnetite-bearing rocks form, the magnetite within them aligns with the Earth’s magnetic field. Since this rock magnetism does not change after the rock forms, it provides a record of what the Earth’s magnetic field was like at the time the rock formed.

Diamond

Arguably, one of the most well-known of the minerals, diamond is unique, not only for its beauty and the high prices it reaches, but also for its properties. Not only is it the hardest known mineral, it is also a great conductor of heat and has the highest refractive index of any mineral.

Though mostly sought after by the jewellery industry, only 20% of all diamonds are suitable for use as a gem. Due to it’s hardness, diamond is mined for use in industrial processes, to be used as an abrasive and in diamond tipped saws and drills. Its optical properties mean it is used in electronics and optics; while it’s conductive properties mean it is often used as an insulator too.

Diamond: perhaps the most sought after mineral of them all? Credit: Hazel Gibson

Olivine

Last, but absolutely not least, let’s talk about Olivine – the winner of #MinCup 2017.

Olivine is a pretty, commonly green mineral. Because it forms at very high temperatures, it is one of the first minerals to take shape as magma cools, and given enough time, can form specimens which are easily seen with the naked eye. Changes in the behaviour of seismic waves as they traverse the Earth indicate that Olivine is an important component of the Earth’s inner layer – the Mantle.

It’s a relatively hard mineral, but overall hasn’t got highly sought-after properties and, as result, has been used rather sparingly in industrial processes. In the past it has been used in blast furnaces to remove impurities from steel and to form a slag, as well as a refractory material, but both those uses are in decline as cheaper materials come to the market.

Perhaps better known is its gemstone counterpart: peridot, a magnesium rich form of Olivine. It has been coveted for centuries, with some arguing that Cleopatra’s famous ‘emeralds’, where in fact peridote. Until the mid-90s the US was the major exporter of the gem stones, but deposits in Pakistan and China now challenge the claim.

So, do you think Olivine was the rightful winner of #MinCup 2017? With a new edition of the popular contest set to return in 2018, perhaps it’s time to shout about the properties and uses of your favourite mineral from the roof tops? Not only might it ensure it is crowned winner next year, but you’ll also be contributing to making the value of minerals known to the wider public. Heck! If you’d like to tell us all about the mineral you think should be the next champion, why not submit a guest post to GeoLog?

In the meantime, if you haven’t already got your hands on one, Hazel tells me there are a few of her charity #MinCup 2017 calendars up for grabs, so make sure to secure your copy – and contribute to a good cause at the same time.

By Laura Roberts Artal, EGU Communications Officer

GeoTalk: The anomaly in the Earth’s magnetic field which has geophysicists abuzz

GeoTalk: The anomaly in the Earth’s magnetic field which has geophysicists abuzz

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Jay Shah, a PhD student at Imperial College London, who is investigating the South Atlantic Anomaly, a patch over the South Atlantic where the Earth’s magnetic field is weaker than elsewhere on the globe. He presented some of his recent findings at the 2017 General Assembly.

First, could you introduce yourself and tell us a little more about your career path so far?

I’m currently coming to the end of my PhD at Imperial College London. For my PhD, I’ve been working with the Natural Magnetism Group at Imperial and the Meteorites group at the Natural History Museum, London to study the origin of magnetism in meteorites, and how meteoritic magnetism can help us understand early Solar System conditions and formation processes.

Before my PhD I studied geology and geophysics, also at Imperial, which is when I studied the rocks that I spoke about at the 2017 EGU General Assembly.

What attracted you to the Earth’s magnetic field?

Jay operates the Vibrating Sample Magnetometer at the lab at Imperial. Credit: Christopher Dean/Jay Shah

My initial interest in magnetism, the ‘initial spark’ if you like, was during my undergraduate, when the topic was introduced in standard courses during my degree.

The field seemed quite magical: palaeomagnetists [scientists who study the Earth’s magnetic field history] are often known as palaeomagicians. But it’s through rigorous application of physics to geology that palaeomagicians can look back at the history of the Earth’s magnetic field recorded by rocks around the world. I was attracted to the important role palaeomagnetism has played in major geological discoveries such as plate tectonics and sea-floor spreading.

Then, during my undergraduate I had the opportunity to do some research alongside my degree, via the ‘Undergraduate Research Opportunities Programme’ at Imperial. It was certainly one of the bonuses of studying at a world-class research university where professors are always looking for keen students to help move projects forward.

I was involved in a project which focused on glacial tillites [a type of rock formed from glacial deposits] from Greenland to look into inclination shallowing; which is a feature of the way magnetism is recorded in rocks that can lead to inaccurate calculation of palaeolatitutdes [the past latitude of a place some time in the past]. Accurate interpretation of the direction of the Earth’s magnetic field recorded by rocks is essential to reconstructing the positions of continents throughout time.

This was my first taste of palaeomagnetism and opened the doors to the world of research.

So, then you moved onto a MSci where one of your study areas is Tristan da Cunha, a volcanic island in the South Atlantic. The location of the island means that you’ve dedicated some time to studying the South Atlantic Anomaly (SAA). So, what is it and why is it important?

The SAA is a present day feature of the magnetic field and has existed for the past 400 years, at least, based on observations. It is a region in the South Atlantic Ocean where the magnetic field is weaker than it is expected to be at that latitude.

The Earth’s magnetic field protects the planet and satellites orbiting around Earth from charged particles floating around in space, like the ones that cause aurorae. The field in the SAA is so weak that space agencies have to put special measures in place when their spacecraft orbit over the region to account for the increased exposure to radiation. The Hubble telescope, for example, doesn’t take any measurements when it passes through the SAA and the International Space Station has extra shielding added to protect the equipment and astronauts.

If you picture the Earth’s magnetic field:  it radiates from the poles towards the Earth’s equator, like butterfly wings extending out of the planet. In that model, which is what palaeomagnetic theory is based on, it is totally unexpected to have a large area of weakness.

Earth’s magnetic field connects the North Pole (orange lines) with the South Pole (blue lines) in this NASA-created image, a still capture from a 4-minute excerpt of “Dynamic Earth: Exploring Earth’s Climate Engine,” a fulldome, high-resolution movie. Credit: NASA Goddard Space Flight Center

We also know that the Earth’s magnetic field reverses (flips its polarity), on average, every 450,000 years. However, it has been almost twice as long since we have had a flip, which means we are ‘overdue’ a reversal. People like to look for signs that the field will reverse soon; could it be that the SAA is a feature of an impending (in geological time!) reversal? So, it becomes important to understand the SAA in that respect too.

So, how do you approach this problem? If the SAA is something you can’t see, simply measure, how do you go about studying it?

Palaeomagnetists can look to the rock record to understand the history of the Earth magnetic field.

Volcanic rocks best capture Earth’s magnetic field because they contain high percentages of iron bearing minerals, which align themselves with the Earth’s magnetic field as the lavas cool down after being erupted. They provide a record of the direction and the strength of the magnetic field at the time they were erupted.

In particular, I’ve been studying lavas from Tristan da Cunha (a hotspot island) in the Atlantic Ocean similar in latitude to South Africa and Brazil. There are about 300 people living on the island, which is still volcanically active. The last eruption on the island was in 1961. In 2004 there was a sub-marine eruption 24 km offshore.

Jürgen Matzka (GFZ Potsdam) collected hundreds and hundreds of rock cores from Tristan da Cunha on sampling campaigns back in 2004 and 2006.

We recently established the age of the lavas we sampled as having erupted some 46 to 90 thousand years ago. Now that we know the rock ages, we can look at the Earth’s magnetic field during this time window.

Why is this time window important?

These lavas erupted are within the region of the present day SAA, so we can look to see whether any similar anomalies to the Earth’s magnetic field existed in this time window.

So, what did you do next?

Initial analyses of these rocks focused on the direction of the magnetic field recorded by the rocks. The directional data can be used to trace back past locations of the Earth’s magnetic poles.

Then, during my master’s research dissertation I had the opportunity to experiment on the rocks from Tristan da Cunha with the focus on palaeointensity [the ancient intensity of the Earth’s magnetic field recorded by the rocks]. We found that they have the same weak signature we observe today in the SAA but in this really old time window.

The rocks from Tristan da Cunha, 46 to 90 thousand years ago, recorded a weaker magnetic field strength compared to the strength of the magnetic field of the time recorded by other rocks around the world.

Some of the lavas sampled on Tristan da Cunha. Credit: Jürgen Matzka

What does this discovery tell us about the SAA?

I mentioned at the start of the interview that, as far as we thought, the anomaly didn’t extend back more than 400 years ago – it’s supposed to be a recent feature of the field. Our findings suggest that the anomaly is a persistent feature of the magnetic field. Which is important, because researchers who simulate how the Earth’s magnetic field behaved in the past don’t see the SAA in simulations of the older magnetic field.

It may be that the simulations are poorly constrained. There are far fewer studies (and samples) of the Earth’s magnetic directions and strengths from the Southern Hemisphere. This inevitably leads to a sampling bias, meaning that the computer models don’t have enough data to ‘see’ the feature in the past.

However, we are pretty certain that the SAA isn’t as young as the simulations indicate. You can also extract information about the ancient magnetic field from archaeological samples. As clay pots are fired they too have the ability to record the strength and direction of the magnetic field at the time. Data recorded in archaeological samples from southern Africa, dating back to 1250 to 1600 AD also suggest the SAA existed at the time.

Does the fact that the SAA is older than was thought mean it can’t used be to indicate a reversal?

It could still be related to a future reversal – our findings certainly don’t rule that out.

However, they may be more likely to shed some light on how reversals occur, rather than when they will occur.

It’s been suggested that the weak magnetic anomaly may be a result of the Earth’s composition and structure at the boundary between the Earth’s core and the mantle (approximately 3000 km deep, sandwiched between the core and the Earth’s outermost layer known as the crust). Below southern Africa there is something called a large low shear velocity province (LLSVP), which causes the magnetic flux to effectively ‘flow backwards’.

These reversed flux patches are the likely cause of the weak magnetic field strength observed at the surface, and could well indicate an initiating reversal. However, the strength of the Earth’s magnetic field on average at present is stronger than what we’ve seen in the past prior to field reversals.

The important thing is the lack of data in the southern hemisphere. Sampling bias is pervasive throughout science, and it’s been seen here to limit our understanding of past field behaviour. We need more data from around the world to be able to understand past field behaviour and to constrain models as well as possible.

Sampling bias is pervasive throughout science, and it’s been seen here to limit our understanding of past field behaviour. This image highlights the problem (black dots = a sampling location). Modified from an image in the supporting materials of Shah, J., et al. 2016. Credit: Jay Shah.

You are coming towards the end of your PhD – what’s next?

So I moved far away from Tristan da Cunha for my PhD and have been looking at the magnetism recorded by meteorites originating from the early Solar System. I’d certainly like to pursue further research opportunities working with skills I’ve gained during my PhD. I want to continue working in the magical world of magnetism, that’s for sure! But who knows?

Something you said at the start of the interview struck me and is a light-hearted way to round-off our chat. You said that palaeomagnetism are often referred to as ‘paleaomagicians’ by others in the Earth sciences, why is that so?

Over the history of the geosciences, palaeomagntists have contributed to shedding light on big discoveries using data that not very many people work with. It’s not a big field within the geosciences, so it’s shrouded in a bit of mystery. Plus, it’s a bit of a departure from traditional geology, as it draws so heavily from physics. And finally, it’s not as well established as some of the other subdisciplines within geology and geophysics, it’s a pretty young science.  At least, that’s why I think so, anyway!

Interview by Laura Roberts Artal, EGU Communications Officer

References and further reading

Shah, J., Koppers, A.A., Leitner, M., Leonhardt, R., Muxworthy, A.R., Heunemann, C., Bachtadse, V., Ashley, J.A. and Matzka, J.: Palaeomagnetic evidence for the persistence or recurrence of geomagnetic main field anomalies in the South AtlanticEarth and Planetary Science Letters441, pp.113-124, doi: 10.1016/j.epsl.2016.02.039, 2016.

Shah, J., Koppers, A.A., Leitner, M., Leonhardt, R., Muxworthy, A.R., Heunemann, C., Bachtadse, V., Ashley, J.A. and Matzka, J.: Paleomagnetic evidence for the persistence or recurrence of the South Atlantic geomagnetic Anomaly. Geophysical Research Abstracts, Vol. 19, EGU2017-7555-3, 2017, EGU General Assembly 2017.

GeoTalk: Peter Lippert, understanding continental tectonics through palaeomagnetic studies

GeoTalk: Peter Lippert, understanding continental tectonics through palaeomagnetic studies

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Peter Lippert, a palaeomagnetist at the University of Utah, and winner of the 2016 EMRP Outstanding Young Scientist Award. He was granted the award for his contributions to insights into palaeoceanography and continental tectonics through palaeomagnetic studies. Crucially, his work using biogenic magnetite – magnetic grains found within organisms – to better understand the Palaeocene – Eocene boundary, is a significant advance in the field.

First, could you introduce yourself and tell us a little more about your career path so far?

I distinctly remember a conversation with my high school 4x800m relay team in which I emphatically stated that I was not interested in pursuing a PhD. At that time, Earth Science wasn’t on my mind, either. I thought I was headed to college to earn a degree in Environmental Engineering and Public Policy.

That changed rather quickly during my first semester at the University of Rochester, when I enrolled in an introductory geology class for mere interest and found myself obsessed with the topic. After two field seasons in the High Canadian Arctic, starting a research project, and seeing Death Valley National Park with the eyes of a budding geologist, I was a geoscience major headed into my junior year of college. I was incredibly fortunate to have great mentors at Rochester who prepared me for and encouraged me to consider graduate school.

I had spent my entire life in the Northeast US, and I was ready to move to the West Coast to begin graduate studies at the University of California, Santa Cruz. I selected the graduate program at Santa Cruz because of the collegiality and creativeness of the department, its reputation for international collaboration, and the strong paleoclimate and tectonics programs there, with the opportunity to carve out my own hybrid of the two. I slogged through graduate school with many of the highs and lows that most graduate students experience, but it was at Santa Cruz where I grew to love international research partnerships, teaching and mentoring undergraduate students, and the transdisciplinary nature of mineral, rock, and palaeomagnetic research.

After a brief stint teaching undergraduate courses at UCSC, I moved to Tucson, where I completed two post-docs fellowships. The first was sponsored by the National Science Foundation Continental Dynamics Program working with 13 other PIs from around the world and a huge cadre of great graduate students and other post-docs to reconstruct the India-Asia collision zone. The second was sponsored by the Canadian Institute for Advanced Research Earth Systems Evolution Program to develop and test new proxies for wildfire in the rock record.

As a complete aside, I also sailed as an expedition palaeomagnetist on the Integrated Ocean Drilling Program Expedition 342 (Paleogene Newfoundland Sediment Drifts) during this time; sailing on Expedition 342 is arguably one of the coolest things I’ve done as a young geoscientist and has paved the way for new collaborations and palaeoclimate studies.

I joined the faculty at the University of Utah in 2014, where I’ve been teaching a mix of undergraduate core courses and graduate classes in structural geology, tectonics, and paleomagnetism.

I’ve spent my entire life in academia working with excellent mentors, colleagues, and students across Europe, Asia, and the US: I would have never predicted this when I was 18 years old, but I wouldn’t want it any other way now.

During EGU 2016, you received the Outstanding Young Scientist Award from the EMRP Division for your work on using biogenic magnetite to understand environmental change and also your use of palaeomagnetism to constrain tectonics. Let’s focus on the latter first and recap on some of the basics (for those readers who may not be so familiar with palaeomagnetism): how can palaeomagnetism studies help in continental reconstructions?

One of the hallmarks of Earth’s geomagnetic field is that if we measure and average its shape near the surface of the Earth over 1000s of years, we find that this shape is explained well by a simple magnetic dipole that is aligned with the spin axis of the Earth.

This approximation, which palaeomagnetists refer to as the Geocentric Axial Dipole (GAD) hypothesis, has two very convenient outcomes: over 1000s of years, the average positions of the geomagnetic poles are coincident with the geographic poles, such that declination— the horizontal component of lines of magnetic flux— points directly away or toward a pole, and that inclination— the vertical component of the magnetic field— is a simple function of latitude.

A simplified geomagnetic field redrawn from Robert Butler's 1992 book "Paleomagnetism: Magnetic Domains to Geologic Terranes".

A simplified geomagnetic field redrawn from Robert Butler’s 1992 book “Paleomagnetism: Magnetic Domains to Geologic Terranes“.

Thus, a package of rocks that forms over several 1000s of years at the equator will have a magnetic inclination of zero, whereas a package of rocks that forms at high northerly latitudes will preserve a magnetic inclination that is nearly vertical, and here in Utah, sediments in the Great Salt Lake are preserving a magnetic inclination that is approximately 60°.

The GAD hypothesis is incredibly powerful for tectonic reconstructions, because if you can date the age of a rock well and measure the magnetic inclination preserved in that rock and demonstrate that the magnetization has not be modified since the rock formed, then you can estimate the latitude at which that rock formed. You can imagine doing this for a series of rocks from the same area but of different ages and measuring if and how the latitude of that area has changed with time.

Paleomagnetic methods, based again on the GAD hypothesis, also provide the only way to quantify vertical axis rotations of large blocks of rock in the geological record. Because the declination always points toward the geomagnetic pole, changes in declination through time can reveal how a block of Earth’s crust, such as a chain of islands or a continent has rotated with respect to the pole or neighbouring blocks of crust. We apply these basic assumptions nearly every day in our research on convergent margin and continental tectonics.

A big chunk of your recent work has focused on using palaeomagnetism to decipher the tectonics of Tibetan Plateau. Could you give us a whistlestop tour of your work in that area?

I’ve been very fortunate to work with diverse and varied international teams throughout China. My graduate work began in Central Tibet and has expanded steadily outward since – in both space and time. I was introduced to Tibet by working on the Palaeogene (66-33 million years ago) tectonics of the central Qiangtang Terrane in the middle of the Tibetan Plateau, which at that time hardly anyone else was working on. I then had the opportunity to join a team working on the long-term slip history of the Altyn Tagh Fault, on the northern edge of the plateau and into the Chinese Gobi, and I have since spent three field seasons working in the remote deserts of the Alxa Region of northwest China, most recently with one of the graduate students in my group and a masters student from China University of Geosciences. I began working in Southern Tibet on India-Asia suture zone palaeogeography just as I started wrapping up my dissertation.

Sunset on Mt. Everest & Rombuk Monastery. Credit: Peter Lippert

Sunset on Mt. Everest & Rombuk Monastery. Credit: Peter Lippert

Through students, postdocs, and my own work, I remain active and invested in each of these regions. In all, I’ve already spent over a year of my life in the high, remote deserts of Western China working with colleagues and students from the US, Canada, Italy, The Netherlands, and several Chinese universities. I can’t say that I have a favorite trip, because each one has its own suitcase of unique memories, but one of the most special was a five week trip to west-central Qiangtang in the autumn 2007, to a very remote region of the plateau. That trip entailed just me, my undergraduate field assistant from Santa Cruz, our guide, and our drivers. The landscape, people, wildlife, and geology were spectacular and rarefied. It was one of the most challenging yet rewarding field seasons I’ve had, and it exemplifies the type of collaborative research and exploration experiences I’m trying to make available to my students and postdocs.

It certainly sounds like your field work has been a highlight of your work! What, would you say, is the biggest finding from your work in the Tibetan Plateau and how does it fit in with the overall geology of the region?

Fieldwork, creativity, and international collaboration are certainly some of the big perks of a career like this. What I regard as our biggest finding is a rather simple one. A large component of my PhD work and the first few years of my first postdoc focused on measuring robust estimates of the latitude of Southern and Central Tibet from 50 million years ago to the present. Our work— and I say our because this has been and continues to be a team effort— demonstrates that the southern margin of the Tibetan Plateau region was positioned at 20°N prior to and at the time pieces of India began colliding with Asia.

This conclusion fundamentally changes the way tectonicists, climate scientists, geodynamists, and paleobiologists think about the India-Asia collision. Previously, much of the community assumed, based primarily on pioneering but outdated and undersampled palaeomagnetic studies, that the India-Asia collision began at 10-12°N latitude and that the most of deformation associated with the collision accumulated in the upper plate of the collision zone (i.e., Asia). Our palaeolatitude estimates require that most of the deformation is instead partitioned into the lower plate of the system, largely by subduction and underthrusting of Indian-associated lithosphere beneath Asia.

Spring 2011 India-Asia Suture Zone field crew including graduate students from the University of Arizona, Utrecht University, and the Institute for Tibetan Plateau Research. Credit: Peter Lippert.

Spring 2011 India-Asia Suture Zone field crew including graduate students from the University of Arizona, Utrecht University, and the Institute for Tibetan Plateau Research. Credit: Peter Lippert.

Moreover, the proto-Tibetan Plateau was located within the high tropics and mostly within the low subtropics at the time collision began and throughout much of its history since. Therefore, we need to reassess how the Tibetan Plateau likely interacted with global atmospheric jets (like the Intertropical Convergence Zone and Westerlies), with important downstream effects on global and regional climate, precipitation patterns in and around the Tibetan Plateau region, physical and chemical weathering and therefore interactions with marine geochemistry, and regional floral and faunal biodiversity. We’re already seeing many different groups critically and creatively addressing each of these topics within this new palaeogeographic framework. By carefully measuring the magnetization of rocks, we can reconstruct a region’s paleogeography, which is, in many respects, a starting point for understanding many Earth System Science processes.

Another big focus of your work is biogenic magnetite. Can you tells more about it and how that fits in with palaeomagnetism?

My research group’s work on biogenic magnetite is quite separate from our research program in convergent margin and continental tectonics, which I love, because that helps keep things fun and intellectually diverse in the group.

Biogenic magnetite represents one of the many ways that rock and mineral magnetism is relevant to so many aspects of Earth System Science. In my group, we study magnetite that is made within the cells of oxygen-sensitive bacteria, so-called magnetosomes produced by magnetotactic bacteria.

Modern forms of these bacteria are genetically diverse, and the shapes of their magnetosomes are also varied, which may be related to the genetic and ecological diversity. We’re testing some of the assumptions that link morphological diversity and the specific ecology of the bugs, as well as methods for in situ magnetic measurements of that morphological diversity, as part of a larger goal of expanding the use of magnetotactic bacteria as biomarkers for specific ecological conditions in aquatic environments.

Simply put, what does the biodiversity of some of the smallest bugs in an aquatic ecosystem tell us about changes in surface processes, such as seasonal run-off, nutrient availability, and temperature, not only today, but also during periods of rapid cooling or warming in the geological record? We work with microbiologists to study these bugs primarily with magnetic measurements, high-resolution electron microscopy, and techniques developed in the materials science and nanotech communities.

UCSC undergraduate students taking in the neotectonics, glacial geomorphology, and volcanic history of the Mt. Morrison region of the Eastern Sierra Nevada as part of a capstone field class for Earth & Planetary Science majors. Credit: Peter Lippert.

UCSC undergraduate students taking in the neotectonics, glacial geomorphology, and volcanic history of the Mt. Morrison region of the Eastern Sierra Nevada as part of a capstone field class for Earth & Planetary Science majors. Credit: Peter Lippert.

We’ll round off the interview focusing on another reason why you have been recognised with this award: your commitment to mentoring and supervising undergraduate and PhD students. Could you tell us more about why you find this element of your work so important?

I’m compelled to quote Jack Kampmeier, the late Professor of Chemistry at the University of Rochester: “Research is teaching at different levels up and down the spectrum. Sometimes you’re teaching undergraduates, sometimes you’re teaching post-docs or visiting faculty members, but you’re always teaching.” And I would add to this that while teaching, you’re always learning.

As a member of an academic faculty, one of the most important things that I can do is help students learn how to learn for themselves, to give them the confidence and encouragement to use those skills to take calculated intellectual risks in pursuing their curiosity for how planetary processes work and to apply them to making their lives better.

I love the viewpoint and energy that an engaged classroom or lab brings to research and learning. Students, post-docs, and colleagues force us to challenge our assumptions and improve our explanations and models in ways that we cannot do on our own, and thus, working closely with students and fostering an environment in which it’s okay to take intellectual risks and question assumptions is a vital, and thankfully really fun aspect of maintaining a creative research program.