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.

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).

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.

Unravelling the elements in ocean sediments

Liao and Tom recently visited the Integrated Ocean Drilling Program (IODP) center in College Station, Texas to analyse sediment cores obtained during IODP expedition 371 to the Tasman Sea. They performed X-ray fluorescence experiments on the cores, a technique that allows to determine chemical compositions of the sediments at very high speeds. This will allow to correlate variations in the magnetic signals, for example, NRM intensities, with variations in iron content along the section.

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