Earth Magnetism and Rock Physics

Looking back at the EGU Blogs in 2016: a competition

Looking back at the EGU Blogs in 2016: a competition

The past 12 months has seen an impressive 360 posts published across the EGU’s official blog, GeoLog, as well as the network and division blogs. From a lighthearted Aprils Fools’ Day post featuring an extreme chromatic phenomenon (otherwise known as FIB); through to how climate change is affecting mountain plant’s sex ratios; features on natural hazard events throughout the year and children’s disarming ability to ask really simple questions that demand straightforward answers, 2016 has been packed full of exciting, insightful and informative blog posts.

EGU Best Blog Post of 2016 Competition

To celebrate the excellent display of science writing across the network and division blogs, we are launching the EGU Blogs competition.

From now until Monday 16th January, we invite you, the EGU Blogs readers, to vote for your favourite post of 2016. Take a look at the poll below, click on each post to read it in full, and cast your vote for the one you think deserves the accolade of best post of 2016. The post with the most votes by will be crowned the winner.

New in 2016

Not only have the blogs seen some great writing throughout the year, they’ve also continued to keep readers up to date with news and information relevant to each of our scientific divisions.

With the addition of WaterUnderground, the network blogs now feature a groundwater nerd blog written by a global collective of hydrogeologic researchers. The new blog is for water resource professionals, academics and anyone interested in groundwater, research, teaching and supervision. Excitingly, it is also the first blog hosted jointly by the EGU Blogs and the AGU blogosphere.

The portfolio of division blogs was also expanded, with the addition of the Tectonics and Structural Geology (TS), Planetary and Solar System Sciences(PS) and Earth and Space Science Informatics (ESSI) blogs back in July. Since then they’ve featured posts on big data, a regular feature showcasing the variety of research methods used in tectonics and structural geology and research from the now iconic Rosetta Mission.

Fissure eruption at Bardabunga in 2014. Photo by Ragnar Th. Sigurdsson, as featured on the TS Blog.

Get involved

Are you a budding science writer, or want to try your hand at science communication? All the EGU Blogs, from GeoLog (the official EGU blog), through to the network and division blogs, welcome guest contributions from scientists, students and professionals in the Earth, planetary and space sciences.

It couldn’t be easier to get involved. Decide what you’d like to write about, find the blog that is the best fit for your post and contact the blog editor – you can find all editor details on the individual blog pages. If in doubt, you can submit your idea for a post via the Submit a Post page on GeoLog, or email the EGU Communications Officer, Laura Roberts, who can help with initial enquiries and introduce you to individual blog editors.

Don’t forget to a look at the blog pages for a flavour of the content you can expect from the new, and existing, blogs in 2017. The blogs are also a great place to learn about new opportunities, exciting fields of research and keep up to date with news relating to the upcoming 2017 General Assembly.


Editor’s note on the EGU Best Blog Post of 2016 Competition: The winning post will be that with the most votes on 15th January 2017. The winner will be announced on GeoLog shortly after voting closes. The winning post will take home an EGU goodie bag, as well as a book of the winners choice from the EGU library (there are up to 4 goodie bags and books available per blog. These are available for the blog editor(s) – where the winning post belongs to a multi-editor blog, and for the blog post author – where the author is a regular contributor or guest author and not the blog editor). In addition, a banner announcing the blog as the winner of the competition will be displayed on the blog’s landing page throughout 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.

Imaggeo on Mondays: Gole dell‘ Alcantara

Imaggeo on Mondays: Gole dell‘ Alcantara

On account of Mount Etna (Europe’s largest volcano), the island of Sicily is peppered with geological wonders. Starting with the summit craters of the volcano itself, right through to over 200 caves formed within lava tubes, the island is packed with volcanic sights.Chief among them is Gole dell ‘Alcantara, a system of gorges formed 8,000 years ago in the course of the river Alcantara in eastern Sicily.

The network of gorges have a maximum depth of 40 m and a width of up to 5 m. They are the result of intense, deep erosion,  of 300,000 year old basaltic rocks, by flowing water. The lavas were once thought to originate from the nearby Monte Moio; an unusual crater not linked to the main Etna volcanic plumbing system. More recent research, including detailed petrographic studies, points towards the craters of Monte Dolce, in the medium-low side of Etna, as being the source of the lavas exposed in the Gole dell ‘Alcantara.

As today’s featured image shows, the lavas exposed throughout the gorge walls are remarkable. Erupting in river waters meant that the lavas cooled faster than they would have done otherwise, giving rise to fractures which formed prismatic structures. Some are chaotic, but others are arranged horizontally (locally known as the woodpile), slightly arching (the harp) and in a radial configuration known as the rosette. The most common configuration is the ‘organ pile’ where vertical fractures form, up to 30m high.

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

GeoTalk: Drilling into the crater which contributed to the demise of dinosaurs

GeoTalk: Drilling into the crater which contributed to the demise of dinosaurs

Six months ago, somewhere in the tropical waters off the coast of Mexico, scientists began drilling into one of the most iconic geological features on Earth: the Chicxulub crater; the 66 million year old remnants of a deadly asteroid impact, thought to have contributed to the demise of dinosaurs and most other forms of life which inhabited the Earth at the time.

Today we speak to Sonia Tikoo, Assistant Professor of Planetary Sciences, Department of Earth and Planetary Sciences, Rutgers University, and one of the researchers part of an international team which is currently trying to decipher the secrets held by the rocks of the Chicxulub crater at a core repository in Bremen.

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

In general, my work involves using the magnetism recorded within rocks to understand problems in the planetary sciences.  I started doing research in palaeomagnetism during college but I really wanted to work in something involving space so I transitioned into planetary science during graduate school.  During my PhD at MIT, I worked on studying the palaeomagnetism of lunar rocks from the Apollo missions to understand the history of the now-extinct lunar dynamo magnetic field.  It was really cool to explore the different ways that small planetary bodies could also generate long-lived magnetic fields lasting a billion years or more.  I subsequently started studying how shock and impact cratering events affect magnetic records within rocks during my postdoc at UC Berkeley, and that experience eventually led me to the work on Chicxulub that I’m doing right now!

Meet Sonia, pictured with colleague William Zylberman, holding up some samples collected from the IODP cores.

Meet Sonia, pictured with fellow palaeomgnetist William Zylberman, holding up some samples collected from the IODP cores.

For those readers who may not be so familiar with the project, could you give us a whistle-stop tour of aims of the research and why it’s important?

In addition to being the crater linked to the demise of the dinosaurs (cool in and of itself!), Chicxulub is also the best-preserved impact structure on Earth and it is the only crater with an intact and well-defined peak ring (a ring of elevated topography within the crater that forms during the collapse stage of crater modification).  As part of IODP/ICDP Expedition 364, we are planning to address a lot of questions regarding this crater, including: (1) how peak rings (stay tuned for our paper on that which is coming out very soon!), (2) how rocks are damaged or weakened by impact shock, (3) how much hydrothermal circulation occurs after the impact, and how long it lasts, and (4) how life recovered within and above the crater following the impact and Cretaceous-Paleogene extinction?

In terms of my specific job…studying the palaeomagnetism of rocks from the crater can be used as a powerful tool to answer some of the aforementioned questions because the magnetizations within rocks can be modified by high temperatures and pressures, and new magnetic minerals can form via hydrothermal activity.  All of these things happen during large impacts on Earth and on other bodies as well, and we see these effects in the crustal magnetism of planetary surfaces.  The entire Science Party is going to be quite busy working on these problems over the next couple years.  What we learn here is not only going to tell us about Chicxulub but also about peak-ring basins across the solar system, and as a planetary scientist I find that angle to be particularly exciting.

What is your role specific role in the project?

Sonia is pictured drilling into cores from the IODP 364 Expedition, to collect smaller samples for palaeomagnetic experiments.

Sonia is pictured drilling into cores from the IODP 364 Expedition, to collect smaller samples for palaeomagnetic experiments.

I’m serving as a palaeomagnetist on the expedition.  There are two groups of scientists associated with Expedition 364 – the Offshore Science Party (the team that recovered the core at sea) and the Onshore Science Party (the team that conducts sampling and preliminary analyses here in Bremen). There wasn’t a magnetometer on the drilling vessel, so I became a member of the Onshore Science Party.  My job here is to collect samples and develop a first-pass dataset of measurements that characterizes the magnetization of the various rock units in the core, spanning both the post-impact sediments and the underlying impactite rocks. The sediment data will eventually be used for magnetostratigraphy and to develop an age model for the post-impact period, and the impactite data gives us a sneak peek at what we will be working with in much greater detail during our post-expedition research as we try to understand the different types of magnetization present in the crater’s peak ring.

So, the experiments are taking place right as we speak?! Can you tell us more about what it is like working at the core repository?

Yes, they are running right now!  Working on an IODP/ICDP expedition is a totally intense, totally rewarding experience!  The Onshore Science Party here in Bremen involves around 45 members of the Onshore Science Party and a team of IODP scientists and technicians working together continuously for a month.

First, one team splits the large drill core into halves.  The core halves then get passed onto teams that do detailed visual descriptions of the cores and some physical properties measurements.

Then the core goes to the sampling room, where we collect specimens for both the immediate measurements we are conducting here in Bremen as well as for the post-expedition research that the Science Party members will be conducting at their home institutions.

Starting bright and early at 7:30 every morning, I drill and prepare sample plugs for moisture and density, P-wave, and paleomagnetic analyses. In the afternoons, I usually shift over to processing magnetic data and writing reports while another paleomagnetist, William Zylberman, conducts measurements in the lab.

The final IODP report writing team. (Credit: Sonia Tikoo)

The final IODP report writing team. (Credit: Sonia Tikoo)

Of course, every other team like physical properties, petrology, biostratigraphy, or geochemistry is doing the same kind of fast-paced work in their own way and we’re always comparing notes and taking advantage of our built-in collaborations. Some scientists have been working on Chicxulub or the K-Pg boundary for decades and others of us (like me!) are first-timers.

There is a fantastic energy associated with having so many talented scientists with all these different avenues of expertise working closely together (and trying to get everything done before our month here is over)!


If you want to learn more about the IODP Expedition and associated research, you’ll find some resources here:


Geotalk is a regular feature highlighting early career researchers and their work.