Weiran Li (Alex)
李蔚然
Lemon Detox
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Abundances of water in magmas revealed by apatite
Volatiles in magmatic systems have large influences on the chemical and physical properties of magmas, which control eruption activities. From my Ph.D. study, I have developed an apatite-based thermodynamic model (ApThermo) for estimating water concentrations in silicate melts. This tool has been developed into online and excel-based calculators.
Collaborator & Ph.D. advisor: Prof. Fidel Costa (EOS, Singapore)
Methods: Thermodynamic modelling on non-ideal mixing in ternary apatite; Modelling on water speciation in silicate melts; Generalised least-squares regression.
Experimental insights into volatile diffusion in apatite: a new tool for estimating magma ascent rates
Diffusion in minerals and melts has been widely used to constrain timescales of magmatic processes. I have performed new experiments to determine the diffusivities of F, Cl and OH in mineral apatite, and developed a three-component diffusion model (ApTimer) to determine the timescales of magma ascent.
Collaborator: Prof. Sumit Chakraborty (Ruhr University Bochum, Germany)
Methods: Experiments + chemical/texture analyses (SIMS, EPMA, EBSD, NRA, TEM) + multicomponent diffusion modelling on apatite
What caused the centennial explosive eruption in 2010 at Merapi volcano?
Merapi volcano, one of the most active volcanoes in Indonesia, changed its usual dome-forming eruptive style in 2010, and produced a large VEI-4 eruption that caused severe impacts on the local community. By investigating chemical compositions of minerals and glass inclusions from the rocks emitted in this event with combination of multiple thermodynamic calculations, we have estimated the magma storage depths at Merapi, and the magmatic volatile budgets and ascent rates before the 2010 eruption.
Collaborator: Dr. Kazuhide Nagashima (University of Hawaii at Manoa, USA)
Methods: Petrography observation + chemical analyses (SIMS, EPMA) of natural minerals (apatite, amphibole, plagioclase, pyroxene) and glass inclusions; Rayleigh fractionation modelling on halogen evolution in melts.
Volatiles and rare earth elements in phonolite from Mt. Erebus (Antarctica): insights into apatite and melt inclusions
Mt. Erebus in Antarctica is famous for its convective lava lake and cyclic degassing over the past half century. By looking into volatile compositions of the melt inclusions and apatite (hosted by anorthoclase megacrystals), we reconstruct the history of volatile evolution and magma transport before eruption. The co-existing apatite and melt inclusions that were formed at nearly isothermal condition also provide us a good opportunity to investigate the partition behaviour of volatiles and trace/rare earth elements between apatite and phonolitic melts with implications for chemical evolution of other alkaline magmatic systems.
Collaborator: Prof. Clive Oppenheimer (Cambridge University, UK)
Methods: Textural/chemical analyses (SEM, EPMA, SIMS, LA ICP-MS) of anorthoclase, apatite and glass inclusions.