CSEDI: Seismological and Geodynamical Study of the Transition Zone Within and Near Subducting Slabs

要了解俯冲板块附近410公里不连续层的动力学及其与橄榄石向b尖晶石和g尖晶石的非平衡过渡之间的联系，需要从多个方面入手。PIs建议：(1)测量转化动力学，水化和热力学性质，从原位(T高达~900（C at P高达~50 GPa）的各种近似的板和地幔组成的红外光谱，并通过回收样品的TEM和岩石学研究阐明机制；(2)利用地震走时和波形模拟来约束5个俯冲带及其附近410 km间断面的橄榄石亚稳性和高程、锐度和速度对比。(3)建立将矿物物理与地震结果联系起来的热动力学模型。这些子区域紧密相连：从红外数据确定的速率规律构成了地球动力学模型的基础，该模型将为计算合成地震记录提供温度分布。与地震传播时和波形的匹配将以高耦合的方式为热动力学建模提供反馈。模型结果将为新的红外实验提供指导。＊＊＊

9712311 Hofmeister A multifaceted approach is needed to understand the dynamics of the 410 km discontinuity near subducting plates and its connection with non-equilibrium transitions from olivine to b- and g-spinel. The PIs propose: (1) to measure transformation kinetics, hydration, and thermodynamic properties from in situ (T up to ~900(C at P up to ~50 GPa) infrared spectra of various approximations to slab and mantle compositions and to elucidate mechanisms through TEM and petrographic studies of recovered samples; (2) to constrain olivine metastability and the elevation, sharpness, and velocity contrast of the 410 km discontinuity in and near five subduction zones from seismic traveltime and waveform modeling. (3) Construct a thermal-kinetic model to link mineral physics and seismic results. The sub-areas are strongly linked: Rate laws determined from the IR data form the basis for the geodynamical model which will provide the temperature distribution for calculating synthetic seismograms. Matching to seismic traveltimes and waveforms will provide feedback to the thermal-kinetic modeling in a highly-coupled manner. Model results will provide guidelines for new IR experiments. ***