Postdoc Spotlight: Kei Shimizu

DTM's Kei Shimizu, January 2018
Kei Shimizu studies the evolution of Earth’s mantle and crust using equipment such as DTM’s Cameca ims-6F ion microprobe, which helps him analyze the geochemistry of mid-ocean ridge basalts. Photo by Roberto Molar Candanosa, DTM.
Monday, January 29, 2018 

Growing up in a small city in Japan where he could often gaze at Mt. Fuji and feel earthquakes, Kei Shimizu may have been destined for geology. As a DTM postdoc—and after a stint into planetary science as a NASA intern—he studies the evolution of Earth's mantle and crust. In this postdoc spotlight, Shimizu tells us about his research and the role it plays in understanding how geochemical processes from millions of years ago shaped the planet as we know it.

Kei Shimizu arrived as a postdoc at DTM in late 2016. Photo by Roberto Molar Candanosa, DTM.

What do you do?

I am a geochemist who studies the chemical composition of igneous rocks, which are made by crystallized magmas or lavas. I study Earth's interior and the igneous process that led to the formation of different igneous rocks using models of magma generation and crystallization.

Magmas or lavas are made by melting of mantle or crust deep in Earth's interior. By studying the chemical composition of igneous rocks, we can learn things about the Earth's interior such as its chemical composition and temperature, as well as how magma is generated inside Earth. I find it very satisfying when I find a nice and simple way to explain the chemical composition of igneous rocks. I also enjoy placing the studied igneous process in the big picture of how Earth has evolved through time.

What is the goal of your research?

As a geochemist, my ultimate goal is to understand how Earth and other planets work. I am approaching this from the perspective of studying igneous rocks, but that is only one aspect of how Earth works. To understand the entire Earth system, collaboration with experts in many other fields is required. Those collaborations include work with scientists ranging from geodynamicists, seismologists, mineral physicists, to climate scientists. In addition, observation of exoplanets and their atmospheric compositions may allow collaboration with astronomers to understand planets beyond Earth and other planets in our solar system.

Studying the chemical composition of igneous rocks is important for many reasons. One of the most fundamental reasons is to understand how igneous processes—along with other processes—have helped shape the Earth in which we live today. Earth is layered into a core, mantle, crust, ocean, and atmosphere. The crust we know today was generated through mantle melting. This process also plays a key role in the cycling of elements essential for life, such as the carbon and hydrogen that help make Earth habitable.

The oceanic crust covers 70% of Earth's surface, and it is formed along mid-ocean ridges such as the one shown here. Spreading of the oceanic lithosphere causes Earth's mantle to rise and melt. The melted material rises to the surface and cools to produce pillow lavas or pillow basalts, forming new oceanic crust at rates of only centimeters per year. DTM's Kei Shimizu analyzes the geochemistry of these basalts to better understand the processes that magmas have undergone and thus have clearer picture of the chemical composition of Earth's mantle. Credit: Roberto Molar Candanosa, DTM. Visualization and video of mid-ocean ridge courtesy of NOAA's Office of Ocean Exploration and Research.

How did you become a geochemist?

I first realized I wanted to become a geochemist when I was an intern at NASA. At that time, I was more interested in the field of planetary science. However, I attended a geochemistry seminar during the internship, and I felt that the knowledge of planetary interior that we can gain through geochemistry was fascinating. After that I started studying the geochemistry of terrestrial rocks and became fascinated in understanding their chemical composition—although I am still very interested in planetary science.

What are you up to at DTM?

I am working on a project to try to understand igneous processes in the oceanic crust that can alter the chemical composition of magma, which is important for making accurate estimates of the carbon content in Earth's mantle. I am also working on a project focused on trying to better understand why igneous rocks formed by melting of Earth's mantle have variable amounts of water. This could be related to recycling of water through subduction or may also be due to shallow processes in the oceanic crust, which is important to distinguish for accurate estimates of water content in Earth's mantle.

What brought you to DTM?

I heard about DTM from my Ph.D. advisor Alberto Saal very early in my Ph.D., since we were collaborating with DTM's Erik Hauri, my current advisor. As I progressed in my studies, I read many papers that were published by scientists at DTM, visited DTM to make measurements using these instruments, and so I felt that it would be a wonderful environment to be able to do a postdoctoral fellowship.

What's your dream job?

I hope that I am still in academia doing research. My dream job is to become a professor at a university. I hope to continue to pursue research related to igneous rocks, particularly on how crystallization of a magma affects its chemical composition.

What word of advice do you have for young scientists?

The advice I would give them is to look for research opportunities at universities and research institutions and explore many different fields in their area of study. I found it useful to explore different fields of research (such as geochemistry, geodynamics, or remote sensing) to really understand what I am especially interested in doing research if I wanted to pursue a graduate degree. I especially recommend research internship programs during the summer, since they allow you to experience what it's like to do research without worrying about classes. It's also a fun experience to become friends with other interns.


—Roberto Molar Candanosa