HKU Department of Earth & Planetary Sciences

A machine learning-based ranking system for more accurate magmatic P–T estimates: an example of pyroxene
Miss Xiaoyu LIU (Supervisor: Prof. Weiran LI)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: March 31st, 2026
Time: 04:30PM
Venue: Room 104, James Lee Science Building

Understanding where magma is stored and how it moves before eruption is important for reconstructing volcanic plumbing systems and interpreting eruptive behaviour. Temperature and pressure are key constraints on these processes and are commonly estimated using mineral-based geothermobarometers. Clinopyroxene (cpx), a common mineral in many igneous rocks, has a wide stability field and a large experimental calibration dataset, making it an important phase for developing thermobarometers. Recent machine-learning studies have produced a number of cpx-based thermobarometer models calibrated using different datasets and algorithms, creating a practical challenge in identifying models suitable for a given magmatic system. Model performance has commonly been assessed using in-distribution data (i.e., data drawn from the same underlying distributions as the calibration dataset), which may underestimate uncertainties when the models are applied to out-of-distribution (OOD) samples. We propose a machine-learning-based framework to rank clinopyroxene-based thermobarometers for given natural samples. The ranking system comprises two parts: (1) applying an OOD detection scheme to exclude unsuitable models and (2) applying deviation functions obtained for individual thermobarometers to predict P–T deviations and identify models giving the lowest deviation. The ranking system was tested using a dataset compiled from published experiments with no overlap with the calibration datasets of the models considered in this study. The P–T estimates of the selected models show lower root-mean-square errors than any single model, with improvements of ~0.4–0.6 kbar and ~10–14 °C. In the Merapi case study, the selected results suggest a broader and more vertically extensive storage system in 2010 than in 2006. Together with previous petrological and geophysical evidence, these results are consistent with deeper, hotter, and more volatile-rich recharge prior to the more explosive 2010 eruption.

For additional information, please contact Miss Xiaoyu LIU, [email protected].

Dynamical Analysis of the 5:1 Mean-motion Resonance of the HD 202206 System
Miss Yingyi CAO (Supervisor: Prof. Man Hoi LEE)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: March 31st, 2026
Time: 04:00PM
Venue: Room 104, James Lee Science Building

The HD 202206 system, featuring two substellar companions in a 5:1 period ratio around a solar-type star, offers a rare opportunity to study high-order mean-motion resonance (MMR) and provides new insights into the dynamical evolution of substellar companions in extrasolar planetary systems. Previous studies established the dynamical structure around the 5:1 commensurability (Correia et al. 2005). More recently, Benedict & Harrison (2017) claimed that this system is nearly face-on, with an inclination of approximately 10°, which implies large masses for the companions, with the inner companion being a low-mass M dwarf. However, this assertation remains controversial. We have performed a new dynamical fit to all available radial velocity data from the CORALIE and HARPS spectrographs. The EXO-STRIKER toolkit was employed for the fitting process (Trifonov 2019). We assessed the long-term stability of the system using a Nested Sampling algorithm. An analysis of the astrometric jitter around the best fit in the Gaia DR3 catalog and the proper motion anomalies between Hipparcos and Gaia showed that the orbital inclinations are strongly constrained to about 51°. Our best-fit dynamical solution, assuming a coplanar and inclined (i = 51°) configuration, yields actual mass of 21.22 MJ and 3.08 MJ for the inner and outer companions, respectively. The corresponding orbital periods are 256.26 days and 1298.69 days, with eccentricities of 0.43 and 0.18. The evolution of the five resonant angles shows that only one of the angles is librating, indicating weak but persistent resonant behavior. Our stability analysis confirms that the system is dynamically stable. HD 202206 c is a giant planet while HD 202206 b is firmly in the brown dwarf regime. Identifying a resonant system that contains both a brown dwarf and a giant planet therefore provides valuable insight into the formation of planets and brown dwarfs, and into the possibility of a continuous transition between the two populations.

For additional information, please contact Miss Yingyi CAO, [email protected].

天問三號火星取樣返回任務
China's Mars Sample Return Mission (Tianwen-3)
劉繼忠 教授 (Prof. Jizhong LIU)
國家航天局天問三號任務總設計師
Chief Engineer of the China’s Mars Sample Return Mission (Tianwen-3)
Date: March 25th, 2026
Time: 10:00 - 11:30 AM
Venue: Room 314A, James Lee Science Building
Language: Mandarin (普通話)

演講摘要：火星被認為是地球以外最有可能存在過，甚至仍然可能存在生命的天體，對其探索有助於回答地球與宇宙中「生命起源」這一重大科學和哲學問題，成為當今行星探測和生命科學研究的焦點。采集樣品返回地球開展研究是實現這一目標的關鍵。本報告回顧了國際深空探測發展歷程与中國深空探測發展現況，介紹了我國天問三號火星取樣返回任務方案，並從科學、技術、工程三個緯度，重點分析火星取樣返回之挑戰與突破。針對火星未來探測的發展與技術難點，倡議國內外科學家聯合開展相關研究，攜手共建火星家園。

嘉賓介紹：劉繼忠，國家航天局探月與航天工程中心研究員，行星探測工程天問三號任務總設計師等。長期從事運載火箭、月球探測、行星探測等國家重大工程戰略研究、規劃論證、總體設計、組織實施和國際合作等方面工作。首批“國家卓越工程師”。曾獲全國五一勞動獎章、國家科學技術進步獎一等獎、何梁何利基金科學與技術進步獎、錢學森傑出貢獻獎、省部級科學技術進步獎等。

For additional information, please contact Prof. Yiliang LI, [email protected].

Mechanisms and hazard modelling of
Multiple Tropical Cyclone Events
Miss Yurong GAO (Supervisor: Prof. Dazhi XI)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: March 24th, 2026
Time: 04:30PM
Venue: Room 104, James Lee Science Building

Multiple Tropical Cyclone Events (MTCEs), in which two or more tropical cyclones co-exist within the same basin, can lead to amplified societal impacts due to cumulative hazards. This presentation reviews current understanding of MTCE climatology and explores factors associated with their development. In addition, a hazard modelling framework empowered by NeuralGCM is introduced. Beyond reproducing individual TC events, it opens new potential for assessing compound hazards such as MTCEs and beyond. Together, these efforts aim to improve the understanding and risk assessment of compound tropical cyclone hazards.

For additional information, please contact Miss Yurong GAO, [email protected].

Intelligent pipeline deposit tracking based on a multi-object tracking framework
Mr. Sihao YU (Supervisor: Prof. Louis WONG)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: March 24th, 2026
Time: 04:00PM
Venue: Room 104, James Lee Science Building

Pipelines play a significant role in transferring energies, materials and fulfilling public needs. However, conventional pipeline maintenance approaches predominantly depend on human inspection of captured closed circuit television (CCTV) records, a process that is particularly labor-intensive and time-consuming for lengthy pipelines. To address these limitations, this study proposes an artificial intelligence-based autonomous framework based on the multi-object tracking (MOT) algorithm for efficient and accurate deposit detection and tracking within pipelines, significantly reducing the need for manual intervention. The proposed MOT model has been trained and validated on a customized pipe CCTV dataset, consisting of more than 12,000 video frames. The experimental results indicate that the combination of YOLOX (for detection) and BYTE (for tracking) achieves the best overall performance among all the tested models. Further testing conducted on a real-world sewer pipeline project demonstrates the robustness of our model. The estimation error of the deposit location predicted by the MOT model is less than ± 0.1 m, with a mean absolute error of only 0.06 m. These findings demonstrate that the proposed autonomous MOT system offers clear advantages over manual inspection, including higher efficiency, reliable accuracy and reduced labor demands, possessing a strong potential for practical engineering applications.

For additional information, please contact Mr. Sihao YU, [email protected].

Investigating Wolf-Rayet Central Stars of Planetary Nebulae
Mr. Zhengjie TIAN
(Supervisors: Prof Zhonghua YAO & Prof Quentin Parker)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: February 24th, 2026
Time: 04:00PM
Venue: Room 104, James Lee Science Building

Planetary nebulae (PNe) are the ejected glowing envelopes of low- to intermediate-mass stars whose central remnant cores (CSPNe) are hot and evolving towards white dwarfs. A subset of CSPNe are hydrogen-deficient with very fast winds that exhibit so-called Wolf-Rayet-like spectra designated as [WR] to distinguish them from their high mass, short-lived counterpart WR stars. Studying these [WR] CSPNe, the objective of my project, provides special insights into late-stage stellar evolution, nucleosynthesis process, binarity, and the chemical enrichment of the interstellar medium. In this study, we investigated the photometric variability of [WR] CSPNe using unique, century-long photographic plate data from the Digital Access to a Sky Century @ Harvard (DASCH) database. Through DASCH data calibration and exploration of other photometric and spectroscopic data, our preliminary results indicate that many [WR] CSPNe exhibit significant photometric variability on timescales ranging from several years to more than half a century. This long-term variability offers insights into potential binary companions and unique, relatively short-time dependencies in the evolutionary processes, such as a very late thermal pulse. Key discoveries will be discussed in this presentation.


For additional information, please contact Mr. Zhengjie Tian, [email protected]

The electrodynamic interaction between Galilean moon and Jovian magnetosphere
Mr. Jinshu CAI (Supervisor: Prof. Binzheng Zhang)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: February 2nd, 2026
Time: 04:00PM
Venue: Room 104, James Lee Science Building

Jupiter possesses the strongest planetary magnetic field in the Solar System, carving out the largest planetary magnetosphere. Inside this system the Galilean moons are embedded and electrodynamically coupled. Ganymede—the largest Galilean moon and the only moon known to possess an intrinsic magnetic field—orbits Jupiter at ~15.0 R_J (R_J=71,492km) close to the Jovian equatorial plane. Because the ambient Jovian plasma flow at Ganymede is typically sub-Alfvénic, the interaction proceeds without a bow shock and can generate Alfvén-wing current systems. Moreover, Ganymede’s intrinsic field introduces additional complexity through magnetic reconnection, magnetosphere–ionosphere coupling, and induction responses potentially linked to a subsurface ocean.
These intertwined processes imply major challenges for interpreting magnetic field morphology and energy transport channels from intrinsic and
interaction-driven perturbation. These issues are central to the launched JUICE mission, which will perform close flybys of Ganymede and carry J-MAG and in-situ plasma and wave instruments to probe the moon’s electromagnetic environment. In this work, a newly developed 3D high-resolution global magnetohydrodynamic (MHD) model with high-resolving power numerical algorithms implemented in spherical coordinate is used to investigate the interaction between Ganymede and Jupiter’s magnetospheric plasma. Building on the MHD framework, we will further conduct fully kinetic particle-in-cell (PIC) simulations to resolve ion/electron-scale physics (e.g., reconnection acceleration and wave–particle coupling) that are beyond single-fluid MHD.

For additional information, please contact Mr. Jinshu CAI, [email protected].

Regional Modeling of Interchange Structures in the Jovian Magnetosphere
Mr. Jiaxing TIAN (Supervisor: Prof Binzheng ZHANG)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: February 2nd, 2026
Time: 03:30PM
Venue: Room 104, James Lee Science Building

Recent Juno wave data shows distinct signatures of interchange activity within Jupiter’s inner magnetosphere. This process plays a key role in the transport of mass, momentum, and energy in a rotation-dominated environment. However, single-spacecraft measurements are limited by spatio-temporal ambiguities, making it hard to get a comprehensive understanding of evolution. This analysis is further complicated by the flapping of the magnetodisc, driven by Jupiter’s tilted magnetic dipole.
To address these limitations, we have developed a novel magnetohydrodynamics (MHD) code designed for both global and regional Jovian models. By employing advanced numerical methods that ensure strict conservation of angular momentum, the code accurately captures the dynamics of Jupiter’s rapidly rotating magnetosphere. The MHD model also incorporates magnetosphere–ionosphere coupling and mass loading from Io’s volcanic activities, while specifically accounting for Jupiter’s dipole tilt to investigate magnetodisk flapping. This modeling framework will facilitate the interpretation of current observational data and provide predictive insights for future Jovian missions.

For additional information, please contact Mr. Jiaxing TIAN, [email protected]

Thermoelastic properties of Mars’ core and an anomalous layer at the Martian core–mantle boundary
Prof. Dongyang Huang Assistant ProfessorSchool of Earth and Space Sciences, Peking University
Date: January 30th, 2026
Time: 10:00AM
Venue: Room 104, James Lee Science Building

Seismic observations made on Mars previously constrained the radius and mean density of its core to be 1830±40 km and 5.7–6.3 g/cm³, respectively. Such a large and light core requires a significant amount of light elements, greater than what was cosmochemically available in the likely building blocks of Mars. This talk will discuss (a) the difficulties encountered by earlier models in accounting for the elastic properties of Mars’ core, (b) how these were reconciled by introducing an anomalous layer at the top of the core, and (c) its implications for Mars’ thermal history. Biography Prof. Dongyang Huang obtained his BE (2013) from China University of Geosciences (Wuhan), China, and PhD (2019) from Institut de Physique du Globe de Paris, France. He was a postdoctoral researcher at ETH Zurich (2020–2024). Since 2024, he has been an Assistant Professor at Peking University. Combining laser-heated diamond anvil cell experiments with first-principles molecular dynamics simulations, his research focuses on the formation and differentiation of rocky planets, and the chemical and physical properties of their interiors. For additional information, please contact Prof. Jiacheng Liu, [email protected].

C-H-O-N Supercritical Fluids in Earth’s Upper Mantle: From First Principles to Machine Learning
Prof Ding Pan (潘鼎)
Associate Professor
Department of Physics and Department of Chemistry
Hong Kong University of Science and Technology
Date: January 30th, 2026
Time: 3:30PM – 4:30PM
Venue: Room 314A, James Lee Science Building

Abstract
Carbon-rich supercritical fluids play a key role in Earth’s deep carbon cycle. While often modeled as simple mixtures, new experimental and theoretical evidence reveals complex reactions. Using first-principles simulations, we found that life-related molecules (e.g., glycine, ribose) can form in these fluids. We also explain RNA’s five-membered ribose ring structure. We further developed first-principles Markov state models to show that CO₂ reacts directly with water in bulk but forms pyrocarbonate intermediates under nanoconfinement. These insights advance understanding of deep carbon cycling and CO₂ storage. Combining quantum molecular dynamics with unsupervised learning helps uncover complex reaction pathways.

[1] Nore Stolte, Rui Hou, Ding Pan, Nat. Commun. 13, 5932 (2022)
[2] Tao Li, Nore Stolte, Renbiao Tao, Dimitri A.Sverjensky, Isabelle Daniel, Ding Pan,
J. Am. Chem. Soc. 146, 31240 (2024)
[3] Chu Li, Yuan Yao, Ding Pan, Proc. Natl. Acad. Sci. U.S.A. 122 (1), e2406356121 (2025)

Biography

Prof Ding Pan obtained BS in physics in the 00 Class (SCGY) at University of Science and Technology of China in 2005, and ScD at Institute of Physics, Chinese Academy of Sciences in 2011. During the ScD study, he was a visiting researcher at the Fritz-Haber-Institute of the Max Planck Society in Berlin, Germany and a Thomas Young Centre Junior Research Fellow at the University College London, UK. He worked as a postdoctoral researcher in the Department of Chemistry at the University of California at Davis (2011-2014) and the Pritzker School of Molecular Engineering at the University of Chicago (2014-2016) before he joined HKUST in 2016. His achievements have been recognized by multiple awards from international scientific organizations, including Croucher Innovation Award in 2018 (HK), Deep Carbon Observatory Emerging Leader Award in 2019 (US), Excellent Young Scientists Award in 2020 (Hong Kong and Macau, Natural Science Foundation of China), and HKUST School of Science Research Award in 2022. (http://angstrom.ust.hk/)

For additional information, please contact Prof. Weiran Li, [email protected]

A tectonic regime transition from mantle plume to subduction in the Neoarchean Abitibi terrane, Superior Craton
Mr. Xin HE (Supervisor: Prof Jian ZHANG)
Department of Earth & Planetary Sciences, The University of Hong Kong
Date: January 27th, 2026
Time: 4:30PM – 5:00PM
Venue: Room 104, James Lee Science Building

The transition from pre-plate tectonic regimes to modern plate tectonics is a pivotal yet contested event in Earth's history. The Neoarchean Abitibi terrane in the Superior Craton preserves a critical record of this transition. This study integrates field mapping, petrography, whole-rock geochemistry, Sm-Nd isotopes, and zircon U-Pb-Lu-Hf-trace element analyses of tonalitic-trondhjemitic-granodioritic (TTG) gneisses, sanukitoids, and associated metavolcanic rocks. Our results document a tectonic regime transition in the Abitibi terrane from an early vertical, mantle plume-dominated system (ca. 2750-2705 Ma) to a later horizontal, subduction- and collision-driven plate tectonic system (ca. 2705-2665 Ma). This transition is marked by a magmatic evolution from reduced, low-H2O TTGs derived from oceanic plateau basalts to oxidized, hydrous sanukitoids sourced from subduction-metasomatized mantle, a finding strongly supported by regional geophysical and structural studies.
By synthesizing global geological records, we further propose that such tectonic regime transitions occurred diachronously across various cratons during the late Archean (~3.2-2.5 Ga), signaling the global onset of plate tectonics.

For additional information, please contact Mr. Xin HE, [email protected].