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固体地球物理学术报告通知--Prof. Sean Shieh

Prof. Sean Shieh
Dept. of Earth Sciences, Western University (Canada) Research Interests Mineral physics; Material study under extreme P-T conditions; Elasticity, Structures and dynamics of the Earth's and planetary interiors; Characterization of materials (e.g. equation of state, phase transition, elasticity, strength, rheology) using synchrotron X-ray, Raman and IR spectroscopy; Exploration of novel and super-hard materials; Material-fluid interaction; high-pressure and high-temperature experiment using a diamond anvil cell.
Study of Zircon and its implications to structure and history of impact craters

Zircon (ZrSiO4) is a common accessory mineral that can be found on Earth, Moon, Mars and meteorites. Due to its unique refractory property, zircon can preserve primary geochemical information for very long time and therefore is popular for age determinations in ancient rocks or impact events. However, deformation and twinning are also found within zircon, indicating that other factors such as stress may also play a key role in altering the shape and microstructure of zircon. Radial X-ray diffraction study of important planetary materials at high pressure, together with microstructure examinations of the quenched samples provides insightful information for better understanding the variations of the elasticity, structure and strength under compression.  In this talk, I will present our recent discovery of old zircon from Moon, and discuss the strength, elasticity and microstructure of zircon at high and room pressure.  In addition, a simple model for the deformation of zircon and its implications to evolution of the impact craters and planets will be discussed.