Using Supercomputers to Understand How Supercontinents Form and Drift Apart

MOVERS AND SHAKERS: USING SUPERCOMPUTERS TO UNDERSTAND HOW SUPERCONTINENTS FORM AND DRIFT APART

PROFESSOR ZHENG-XIANG LI, OF CURTIN UNIVERSITY IN WESTERN AUSTRALIA, HAS COMBINED HIS LOVE OF TRAVEL WITH A LIFE-LONG INTEREST IN NATURE TO STUDY THE PROCESSES THAT SHAPE THE EARTH. HIS RESEARCH GROUP USE SUPERCOMPUTERS TO MODEL THE CHANGES TO OUR PLANET OVER THE PAST TWO BILLION YEARS, IN A PROCESS CALLED 4D GEODYNAMIC MODELLING

Professor Zheng-Xiang Li, based at Curtin the rocks are solidified, these minerals IMAGINE THIS University’s School of Earth and Planetary become “locked in” and act like tiny magnets Sciences in Australia, has spent his career or compasses. By studying these magnetic A continent is one of Earth’s seven main trying to understand the forces that shape minerals, or needles, Li and his team are able divisions of land: Asia, Africa, North our planet. to track how continents have moved over time America, South America, Antarctica, Europe and look for patterns, which they can then and Australia. These continents sit on Li is a leader in the field of Earth dynamics (a compare to what they know about Earth’s tectonic plates that move around the planet branch of geophysics), and he and his team internal geometry today. at speeds of a few centimetres a year. Over have been working on a project that aims to millions of years, continents move towards understand how the Earth works. They are The researchers are also modelling the forces each other to form supercontinents, before doing this by studying plate tectonics – a that drive the formation and breakup of breaking up again and moving away from scientific theory that describes the surface of supercontinents. Every 500-700 million each other – again, over millions of years. the Earth as an outer shell divided into plates years, 75% or more of the Earth’s landmasses The last supercontinent, known as Pangea, is – and investigating how these tectonic plates join together to form a single mass known as believed to have formed around 320 million interact with deeper Earth over time. a supercontinent. One of the key questions years ago. that Li and his team would like to answer is WHAT EXACTLY ARE LI AND how many supercontinents have formed over The continents are surrounded by one HIS COLLEAGUES TRYING TO Earth’s history. continuous body of water, which is divided up UNDERSTAND? into four oceans: the Pacific, Atlantic, Indian Our planet formed about 4.5 billion years ago; HOW DO THEY INVESTIGATE HOW and Arctic Oceans. A superocean is defined Li’s group is focusing on the past 2 billion years. SUPERCONTINENTS FORMED as a continuous body of water surrounding a Because we cannot see directly into the deeper MILLIONS OF YEARS AGO? supercontinent. For example, according to Earth and study how things work down there, “New geophysical imaging techniques allow us worldatlas.com, the Panthalassa superocean it has been difficult for scientists to figure out to gain increasingly clear images of what the surrounded the supercontinent Pangea. how tectonic plates work. deep Earth looks like,” says Li, “and powerful supercomputers let us simulate how Earth’s How long do you think it will be before the Li’s group aims to understand how the Earth tectonic plates interact with the deeper Earth next supercontinent and superocean form? has evolved over the past 2 billion years with increasing resolution, and further back through palaeomagnetism, a branch of in time.” geophysics that studies magnetism in rocks. Indeed, cutting-edge geophysical techniques, As magma or lava cool (or when fine sediments which allow the precise dating of geological settle at the bottom of seas and lakes), tiny events and the analysis of the physical and iron-bearing minerals in the rocks or sediments chemical nature of rock samples, have enabled align with the Earth’s magnetic field. Once scientists to gather a wealth of data from

00 Find this article, and others like it, online at www.futurumcareers.com Li’s research takes him to places all over the world, like Madagascar, pictured here.

PROFESSOR ZHENG-XIANG LI John Curtin Distinguished Professor School of Earth and Planetary Sciences Curtin University, Australia.

FIELD OF RESEARCH Earth Dynamics

RESEARCH PROJECT around the world. Li’s group has been feeding such, Li is working with key partners, including Li and his team are using cutting- this information into supercomputers and Prof David Evans of Yale University, USA, edge techniques to create computer using tools, including artificial intelligence (AI), who specialises in palaeomagnetism and world simulations of how plate tectonics have to mine this data and look for patterns. One geology; Prof Shijie Zhong of the University reshaped our planet over the past 2 billion method of computer simulation is known as of Colorado, USA, who is an expert in the years. 4D geodynamic modelling, which uses physics, digital simulation of the geodynamic system; chemistry, mathematics and geoscience Prof Bruce Eglington of the University of knowledge to model the geographical Saskatchewan, Canada, who specialises in the FUNDER distribution of rocks in three dimensions establishment of global geological databases (3D) – length, width and depth –, then work that allow researchers to apply a big data Australian Research Council out how this distribution changes over time. approach to their studies; and Prof Dietmar These time changes are known as the fourth Muller of the University of Sydney, Australia, dimension (4D). who specialises in marine geophysics and led the development of the GPlates software, WHY IS IT IMPORTANT TO INCREASE WHAT HAS LI’S GROUP DISCOVERED which enables scientists to build 3D models of OUR KNOWLEDGE OF GLOBAL SO FAR? global plate tectonic evolution through time. TECTONICS? Working with other research teams from “Earth’s tectonic evolution has impacted different countries, Li’s team has discovered WHAT ARE THE NEXT STEPS FOR LI’S the formation of the atmosphere, which a piece of landmass from North America that RESEARCH PROJECT? we breath, and the behaviour of the Earth’s stuck to, and subsequently travelled with, Research can be a slow process. In fact, there geomagnetic field, which protects the Australia about 1.6 billion years ago, when both is even a term for this: “slow science”. This atmosphere, the hydrosphere and all life countries were part of the same supercontinent is because it can take years to gather the on Earth – like a giant shield – from the known as Nuna. evidence needed to prove or disprove theories. bombardment of the Sun’s strongly charged Indeed, Li reckons it will take at least another particles, known as the solar wind,” explains Li. The researchers have also suggested that 20 years before he can provide more definitive there might be a “superocean cycle” – which answers to some of the science questions he is By investigating the evolution of tectonic describes the formation and dissipation of huge hoping to answer. plates, Li and his colleagues are furthering our oceans. This superocean cycle is believed to understanding of their effects on landscapes, take place over about 1.2 billion years compared But slow science does not translate into soils, minerals and fossil fuels – all of which to the supercontinent cycle, which takes “boring science”! Quite the opposite, as Li are vital to society in so many ways, from roughly 600 million years to complete. says: “My team is evolving as the project agriculture to energy supply and product evolves, with some younger members moving development. Moreover, knowledge about WHY IS LI WORKING WITH OTHER to other institutions around the world to tectonics is essential if we are to fully RESEARCH TEAMS FROM ALL OVER develop their independent careers, and new understand and survive geohazards such as THE WORLD? members joining us with support from new earthquakes, volcanos and tsunamis. So, while As Li explains, “The scope of this project is funding sources. All of us, along with our curiosity about how planet Earth really works so large that it is crucial to work with a wide other collaborators, are continuing to pursue might get you started in a career in geology range of specialists with knowledge covering all this exciting research field as an expanding or geophysics, your studies in Earth dynamics key disciplines and geographic locations.” As international network.” will underpin life as we know it.

00 ABOUT EARTH DYNAMICS

each other, a fault line will have formed. Planet Earth is a sphere, composed of several, kilometres, albeit over a long period of time. Sometimes the plates stick and forces build distinct layers. The outermost layer is known up – eventually the force is released in a as the crust and is made of solid rock, between Periodically, many of the landmasses join violent jerk, causing an earthquake. 8 and 50km thick. This crust, together with together to form a supercontinent, before the topmost layer of mantle under it, forms breaking apart again. This supercontinent cycle WHY SHOULD STUDENTS STUDY a mosaic of rigid plates that float upon a takes place over 500 to 700 million years. EARTH DYNAMICS? mushy layer of the mantle, known as the The study of geology or geophysics can lead asthenosphere. Over time, these plates move HOW ELSE HAVE THESE MOVING to a wide range of exciting and rewarding around the globe. PLATES AFFECTED OUR PLANET? When plates collide, new mountain ranges careers. Plate tectonics have an impact on the formation of our atmosphere, the WHAT EFFECT DOES THIS HAVE ON might form between them; when they Earth’s geomagnetic shield (which protects OUR PLANET? move apart, new oceans may appear. In us from the solar wind – dangerous, highly Everything that we see on Earth, from the some areas, hot, molten rock from deep charged particles emitted by the Sun) and landmasses that make up the continents and below bursts through in a volcanic eruption. our landscape. The rocks, minerals and fossil islands, to the oceans and seas, rests upon Scientists can map these eruptions and use fuels that we rely on every day were formed these plates. Over time the position of these the information to probe deeper into the through the action of plate tectonics. continents and oceans changes. Although Earth. Scientists studying this area also aim to help these plates move extremely slowly – only us understand and survive hazards such as a few centimetres per year – over tens of CAN WE SEE EVIDENCE OF THESE earthquakes, volcanoes and tsunamis. millions of years this movement adds up, PLATES MOVING TODAY? meaning continents can shift thousands of Yes. Where the plates rub up against

OPPORTUNITIES IN GEOPHYSICS • The Geological Society of Australia is a great place to find information about geology, including courses: https://www.gsa.org.au/.

• The Australia-based Geoscience Pathways website has lots of interesting resources for students who are still at school, including information about

careers in this area and what to study at This image shows a proposed supercontinent–superplume coupling since 900 million years ago (Ma). This university: coupling started at least since 2000 Ma. A superplume is a large body of hot rock within deep Earth, some http://www.geosciencepathways.org.au. of which is convected to the Earth’s surface. Can you find the supercontinents Rodinia and Pangea? It is believed that we are currently halfway through the formation of another supercontinent known as Amasia, but scientists have different views on what Amasia will look like and where it will centre. • The Australian Geoscience Council (https://www.agc.org.au/) has lots of information, including the regular GeoEdLink newsletter aimed at educators This is a geodynamic working and the public. model of coupled supercontinent and superplume events. https://www.agc.org.au/geoedlink- newsletter/.

• Careers in geology can be well paid. Entry-level positions generally start at about AUD$ 44,000 per year, averaging to over $120,000. The most experienced workers can make over $200,000.

00 Find this article, and others like it, online at www.futurumcareers.com ASK PROF ZHENG-XIANG LI

WHAT DID YOU WANT TO BE WHEN went into this subject almost by accident. WHAT DO YOU LOVE MOST ABOUT YOU WERE GROWING UP? However, I soon developed a love of it YOUR JOB? I grew up in China during the Cultural because of my love of travel, and the subject The freedom to follow my own interests; the Revolution, when the country was going involves a lot of physics, too. excitement of a brand-new discovery or idea through a period of social upheaval and and being able to share it with likeminded almost all the universities were shut. So, COULD YOU DESCRIBE A TYPICAL people, plus the opportunity to see remote during my school years, I wanted to become DAY FOR YOU AS A MEMBER OF corners of the world and experience a schoolteacher. The only other option at THE EARTH DYNAMICS RESEARCH different cultures. that time for me would have been to work GROUP? in fields. Towards the end of my school When not attending conferences or WHAT HAS BEEN YOUR GREATEST years, the Cultural Revolution ended, geological field trips, we spend much of ACHIEVEMENT TO DATE? and universities reopened. I then started our day reading scientific papers (finding Developing a new understanding about how dreaming of becoming a physicist! out what’s new), acquiring and interpreting the Earth engine works, i.e. discovering both our own and others’ results, discussing the conceptual model that plate tectonics YOU HAVE A BS DEGREE IN new results and exciting new ideas with interact with mantle dynamics through SEISMOLOGICAL GEOLOGY FROM colleagues, and writing these up as scientific coupled supercontinent-superplume PEKING UNIVERSITY. WHAT DREW papers, when these results and ideas are cycles, and that superoceans likely outlive YOU TO THIS SUBJECT? mature enough to be shared with the global supercontinent cycles. I was always interested in nature but science community.

LI’S TOP TIPS

01 Have an inquisitive mind and a thirst for knowledge.

02 Follow your own interests (which can change over time).

03 Do things with passion!

The Earth Dynamics Research Group at Curtin University