Determination of single-crystal elastic properties of olivine and serpentine as a function of chemical composition at conditions of subduction zones up to GPa, 1000°C

在高达 GPa、1000°C 的俯冲带条件下测定橄榄石和蛇纹石的单晶弹性性质与化学成分的函数关系

• 批准号: 141459519
• 负责人: Dr. Sergio Speziale
• 金额: --
• 依托单位: Institut für Geologie und Mineralogie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/141459519?language=en
• 关键词: Determination; single; crystal; elastic; properties

We plan to determine the elastic properties of single-crystal olivine at conditions relevant for the subducted oceanic lithosphere up to 600 km depth along various pressure-temperature profiles corresponding to different subduction geometries. The elastic properties will be de-termined by Brillouin scattering in-situ at high pressure and high temperature (up to 25 GPa and 1000 ºC). We will synthesize and study olivine with different Fe contents and with differ-ent OH contents, covering the whole compositional range for this phase in the upper mantle. In addition, we also plan to measure the sound velocity of serpentine aggregates within the antigorite stability field, at pressures and temperatures relevant for subduction regimes. In parallel to the experimental study, we will perform numerical simulations of the same materi-als with special interest in the elastic properties in order to predict the elastic behavior at conditions outside the accessible experimental range. We will also investigate by computa-tional methods the mechanisms and conditions for plastic deformation and structural phase transitions in the olivine system. Our results will provide for the first time information about the effect of temperature, pressure and composition on the elastic anisotropy of the most abundant mineral of the upper mantle, and its most common alteration product. In fact, elas-tic anisotropy of olivine and serpentine play a crucial role in the subduction geodynamic set-ting that is characterized by the presence of large deviatoric stresses and plastic deforma-tion of rocks with development of lattice preferred orientation and seismic anisotropy.

我们计划确定的弹性性能的单晶橄榄石在相关的条件下，俯冲大洋岩石圈的深度可达沿着各种压力-温度剖面对应于不同的俯冲几何形状的600公里。弹性特性将通过在高压和高温（高达25 GPa和1000 ºC）下的现场布里渊散射来确定。我们将合成和研究不同Fe含量和不同OH含量的橄榄石，涵盖上地幔该相的整个成分范围。此外，我们还计划在俯冲机制相关的压力和温度下，测量叶蛇纹石稳定场中蛇纹石聚集体的声速。在实验研究的同时，我们将对同样的材料进行数值模拟，特别关注弹性特性，以预测在可接近的实验范围之外的条件下的弹性行为。我们还将用计算方法研究橄榄石系统中塑性变形和结构相变的机制和条件。我们的研究结果将首次提供有关温度、压力和成分对上地幔最丰富的矿物及其最常见的蚀变产物的弹性各向异性的影响的信息。事实上，橄榄石和蛇纹石的弹性各向异性在俯冲地球动力学背景中起着至关重要的作用，俯冲地球动力学背景的特征是存在大的偏应力和岩石的塑性变形，并伴随着晶格择优取向和地震各向异性的发展。