Marine Magnetism @PKU

Rock Magnetism in Marine Environments at Peking University.

  • Unravelling hydrothermal alteration in basaltic ocean crust

    Seafloor hydrothermal vents, also known as black chimneys (featured image; Copyright: Woods Hole Oceanographic Institution), produce valuable mineral resources through fluid-rock reactions beneath the seafloor – a process called hydrothermal alteration. On basaltic ocean crust, hydrothermally-altered regions are generally found to be less magnetic, which provides a way to detect seafloor hydrothermal vents. By collaborating with Prof. Chunhui Tao group from the Second Institute of Oceanography, we analyzed a large set of rock samples recovered from the Southwest Indian Ridge. Results were recently published in Geophysical Research Letters (Wang et al., 2020; https://doi.org/10.1029/2020GL087578) that discloses the detailed alteration pathway in hydrothermal vent hosting mid-ocean ridge.

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  • Dr. Chang was awarded a Royal Society-Newton Advanced Fellowship

    Dr. Chang was recently awarded a personal fellowship – a Newton Advanced Fellowship from the UK Royal Society. This fellowship provides funding support for Dr. Chang and his group for collaborating with Prof Richard Harrison group at the Department of Earth Sciences, Cambridge University, on a project entitled ‘A machine-learning approach to multiscale environmental magnetism’. This project will employ sets of cutting-edge nanoscale 2D/3D imaging techniques, machine-learning based data analyses, and computational modelling to develop new multiscale environmental magnetic analytical tools. The new tools will enable extracting key environmental signals from natural samples at an unprecedent level. Additional funding support for this project is provided by the National Natural Science Foundation of China (NSFC).

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  • Dating mega-tsunamis in Cape Verde

    Tom recently went to Cape Verde together with Dr. Ricardo Ramalho to sample tsunami deposits of an ancient mega-tsunami. These deposits, first found by Ricardo and published in Science Advances, were created 73,000 years ago during a flank collapse of nearby Fogo Volcano that caused a tsunami wave of at least 170 meters height. At PKU we are now working on a new method to date tsunami deposits that were previously impossible to date using conventional methods such as cosmogenic dating.

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One of the world's leading laboratories in environmental magnetism, sedimentary magnetism and magnetic modelling.

People

We are currently three researchers and three graduate students. We are also looking for new post-docs and students interested in working on environmental magnetism in China’s capital.

Dr. Liao Chang

Dr. Liao Chang is an Assistant Professor and Principal Investigator at the School of Earth and Space Sciences at Peking University. He is heading an active group of several post-docs and students, addressing a wide range of problems in rock and mineral magnetism, environmental magnetism, remanence acquisition, and marine geology and geophysics.

Dr. Thomas Berndt

Tom is an Assistant Professor at the Geophysics Department, Peking University. He held a PKU Boya postdoc fellowship. Tom obtained PhD from Imperial College London for his work on viscous remanent magnetization dating of floods. He held a MSc in Geophysics from the University Complutense Madrid, Spain and a BSc in Physics from the University of Southampton.

Dr. Joy Muraszko

Joy is currently a postdoc fellow at the School of Earth and Space Sciences at Peking University, funded by the Chinese postdoc research council. She completed her PhD at the Earth Science Department of the University of Cambridge, working on applications of FORC diagrams for environmental magnetism.

Shishun Wang

Shishun is currently a Ph.D candidate at Peking University. He held a BSc in Geology from Peking University. His Ph.D project is about geodynamics and magnetic anomalies in the Mid-Ocean Ridges. He also works on geomagnetic secular variations and environmental magnetism in the Bay of Bengal.

Pengfei Xue

Pengfei is a Ph.D student at the School of Earth and Space Sciences, Peking University. He obtained a BS.c in geology from Jilin University, China. His Ph.D project is using mineral magnetic records to reconstruct paleoclimatic changes, i.e. the Eocene global warming events.

Fan Bai

Fan Bai is a Ph.D student at the School of Earth and Space Sciences, Peking University. Before, she majored in exploration technology and engineering in China University of Petroleum.

Research

Viscous remanent magnetization dating of floods

This is a new technique where we collect samples from large tsunami boulders (recently from Cape Verde) that were quarried and rotated during the tsunami. Afterwards they slowly acquire a viscous remagnetization whose intensity/blocking temperature increases over time. By measuring this viscous remagnetization, we can calculate the age of the tsunami.

Micromagnetic modelling

We use a full finite-element micromagnetic model (MERRILL) to simulate the magnetic properties of complex magnetic mineral ensembles, such as biogenic magnetite/magnetotactic bacteria and magnetic mineral inclusions in silicates, that are widely present in many natural environments. We seek to link the simulation with experimental data to detect subtle changes reflected in magnetic proxies throughout sedimentary records.

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Sediment remanence acquisition

Investigating DRM/PDRM/CRM processes to understand how marine sediments get magnetized. We use a combined experimental and numerical approach: we do laboratory redeposition experiments under controlled conditions, and also build numerical models in order to get a better picture of the magnetic recording processes in marine sediments.

Paleoenvironmental and paleoclimate reconstructions

Magnetic proxies are widely used in paleoenvironmental reconstructions. However, traditional environmental magnetic approaches rely heavily on simple magnetic parameters and their ratios. We take a different approach: we determine magnetic property variations from direct observation of magnetic minerals, and combine these with advanced rock magnetism, mathematical unmixing, and magnetic modelling. This helps to get more robust magnetic proxies for tracing environmental processes.

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Fundamental rock and mineral magnetism

Understanding the complex magnetic records in natural materials requires knowledge of the fundamental magnetic properties of their minerals. We investigate the common terrestrial magnetic minerals, including iron sulphides, iron oxides, iron-titanium oxides, that have origins from either chemical precipitation, biological synthesis or environmental weathering. Studies range from atomic-scale magnetic mineral structures to macro-scale fundamental rock magnetic properties.

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Recent News

Unravelling hydrothermal alteration in basaltic ocean crust

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Seafloor hydrothermal vents, also known as black chimneys (featured image; Copyright: Woods Hole Oceanographic Institution), produce valuable mineral resources through fluid-rock reactions beneath the seafloor – a process called hydrothermal alteration. On basaltic ocean crust, hydrothermally-altered regions are generally found…

Read More Unravelling hydrothermal alteration in basaltic ocean crust

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