US-France Cooperative Research: Rheology of the Transition Zone of Earth's Mantle

该奖项将支持纽约州立大学石溪分校的Robert Liebermann博士和巴黎第六大学地球物理研究所的Jean-Paul Poirier博士在地球物理学方面的合作研究。这项研究的目的是更好地了解地幔矿物高压相流变行为。具体地说，研究人员提议在石溪的大体积单轴分裂球体装置中合成橄榄石和辉石的高压相样品，并在巴黎使用透射电子显微镜研究它们的变形。将特别注意含有尖晶石和石榴石混合物的相组合，以及在P-T条件下合成的跨越石榴石-钛铁矿相边界的样品。这些新数据将被用来解释发生在地幔过渡带的动态过程。这些研究还与俯冲过程的动力学和岛弧下深源地震的发生有关。美国和法国的实验室完全有资格从事这一项目。Poirier博士和他的同事们已经开发出在钻石砧座装置中在高压和温度下产生共存相的技术，并使用透射电子显微镜检查了实验室中合成或自然陨石撞击产生的高压相的微观结构。位于石溪的美国实验室是一个国际高压测量中心。

This award will support cooperative research in geophysics between Dr. Robert Liebermann, State University of New York at Stony Brook and Dr. Jean-Paul Poirier, Institut de Physique du Globe, University of Paris VI. The objective of this research is a better understanding of the rheological behavior of the high-pressure phases of mantle minerals. Specifically, the investigators propose to synthesize specimens of high pressure phases of olivine and pyroxene in the large-volume, uniaxial split-sphere apparatus at Stony Brook and to study their deformation using tranmission electron microscopy in Paris. Special attention will be devoted to phase assemblages which contain mixtures of spinel and garnet and to specimens synthesized at P-T conditions which straddle the garnet-ilmenite phase boundary. These new data will be utilized to interpret the dynamic processes occurring in the transition zone of the Earth's mantle. These investigations also have relevance for the dynamics of the subduction processes and the occurrence of deep focus earthquakes beneath island arc regions. The U.S. and French laboratories are well qualified to pursue this project. Dr. Poirier and his colleagues have developed techniques to produce co-existing phases at high pressures and temperatures in diamond-anvil-cell apparatus and used transmission election microscopy to examine the microstructure of high pressure phases produced synthetically in the laboratory or naturally by meteorite impact. The U.S. laboratory at Stony Brook is an international center for high pressure measurement.