名家论坛（2017-10）：杜蔚副研究员学术报告会

应地质过程与矿产资源国家重点实验室叶宇和巫翔教授邀请，北京大学地球与空间科学学院杜蔚副研究员来我校进行学术交流并作学术报告。

报告题目：镁铝榴石-钙铝榴石固溶体的矿物结构及其稳定区间

报告时间：2017年6月16日下午14：30

报告地点：东区地矿国重一号会议室（103）

杜蔚副研究员简介：

现任职北京大学地球与空间科学学院副研究员。2002年和2005年分别在北京大学地球与空间科学院获得学士和硕士学位。2012年获得美国哥伦比亚大学博士学位，师从著名地质学家David Walker教授，主要科研领域是高温高压实验在地球科学的应用。并先后在美国纽约州立大学石溪分校（2012-2013）和日本东京工业大学（2014-2016）从事博士后研究工作。科研兴趣包括矿物在高温高压条件下的物理和化学性质变化，地球深部条件下的矿物组成以及矿物相平衡；地幔物质在部分熔融情况下的物理性质及对地震波速可能的影响。近年来的科研兴趣集中在太阳系星体的物质组成，早期形成以及演化。通过高温高压实验手段对陨石样品进行熔融，建立可能的早期星体的形成模型。先后在American Mineralogist, Physics and Chemistry of Minerals, Physics of the Earth and Planetary Interiors等国际重要的矿物学杂志上发表十余篇论文。

内容简介：Garnet is a major phase in Earth mantle models such as pyrolite and piclogite (Irifune and Ringwood 1987, 1993) and garnet volume fraction may increase to more than 40% in the Earth’s transition zone (410-660km) (Duffy and Anderson 1989). They are stable over a wide pressure and temperature range and compatible with phases such as mica, pyroxene, and olivine, making them important candidates for geothermal barometers and thermometers. Knowledge of the effect of compositional change on the physical properties of garnet is essential for the correct interpretation of regional lateral variations in seismic velocity imaged by seismic tomography and geodynamic studies of the continental lithosphere in terms of thermal and chemical properties. The garnet binary pyrope-grossular (Mg3Al2Si3O12-Ca3Al2Si3O12) provides an excellent solid-solution system for the study of non-ideal mixing behavior, because of the large size difference between divalent Mg2+ and Ca2+ (0.89 vs 1.12 in 8 coordination) (Shannon 1976). To clarify the disagreements among the literature studies and to further constrain the mixing properties of pyrope-grossular garnet solutions, I have performed experimental studies on synthesized garnet solid solution by using multi-anvil device, comprehensive X-ray diffraction powered with synchrotron light sources. Our new results show that the nonlinear compositional dependence of thermo-compression may be related to the elastic structural strain caused by substitution of Mg and Ca. And the exsolution of pyrope-grossular garnet at high pressure is confirmed by laboratory observation for the first time. I will discuss the details about the non-linear composition dependence of mixing properties along pyrope-grossular garnet and their application.

地质过程与矿产资源国家重点实验室

地球科学学院

2017.6.15