Water partitioning between coexisting olivine (ol) and wadsleyite (wads) and the effect of the OH-defect concentrations on the P-T-x coordinates of the ol-wads phase transformation

共存橄榄石 (ol) 和 wadsleyite (wads) 之间的水分配以及 OH 缺陷浓度对 ol-wads 相变 P-T-x 坐标的影响

• 批准号: 25249801
• 负责人: Professorin Dr. Monika Koch-Müller
• 金额: --
• 依托单位: Department 3: Geochemie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/25249801?language=en
• 关键词: Water; partitioning; between; coexisting; olivine

The seismic discontinuity at 410 km depth within the Earth¿s mantle is believed to be caused by the transformation of olivine (ol) to wadsleyite (wads) (e.g. Dziewonski and Anderson, 1981). Recent seismic observations indicate that the discontinuity is not as sharp as observed in experiments (e.g. Zhang and Herzberg, 1994) but shows a wide range of thicknesses from about 4 km (e.g. Benz and Vidale, 1993).) to 35 km (van der Meijde et al. (2003). Based on theoretical studies (Wood, 1995; Helffrich and Wood, 1996) van der Meijde et al. (2003) interpret the observed broadening of the 410 km discontinuity as being caused by water incorporation in the coexisting mantle minerals ol and wads. If this is true, varying thicknesses of the discontinuity indicate variable and inhomogenous distribution of water in the upper mantle. However, up to now it has not been confirmed unquestioningly by experiments how water incorporation into the mantle minerals ol and wads influence the phase boundaries between the minerals (Smyth and Frost, 2002; Chen et al., 2002). To fully understand the water cylcle of the Earth and its effect on the Earth¿s structure more experimental data are needed. The goals of this project are to experimentally determine (i) the water saturation of coexisting olivine and wadsleyite under mantle conditions, and (ii) the effect of water on the P-T-x coordinates of the ol-wads phase transition in quenched multi-anvil experiments as well as in-situ in laser heated diamond anvil experiments. On the base of these studies a future project in the second application period will deal with (iii) the influence of water on the mechanisms and kinetics of the ol-wads phase transition.

地球内部 410 公里深度的地震不连续性¿地幔被认为是由橄榄石 (ol) 向瓦兹利石 (wads) 的转变引起的（例如 Dziewonski 和 Anderson，1981），最近的地震观测表明，不连续性并不像实验中观察到的那么明显（例如，Zhang 和 Herzberg， 1994），但显示了从约 4 公里起的广泛厚度（例如 Benz 和 Vidale，1993）。至 35 公里（van der Meijde 等人（2003）。根据理论研究（Wood，1995；Helffrich 和 Wood，1996）van der Meijde 等人（2003）解释了观察到的 410 公里不连续性的扩大是由于如果这是真的，则不连续性的不同厚度表明存在变量。然而，迄今为止，尚未通过实验毫无疑问地证实水掺入地幔矿物 ol 和 wads 中如何影响矿物之间的相界（Smyth 和 Frost，2002；Chen 等人）。 .，2002）。充分了解地球的水循环及其对地球的影响¿该项目的目标是通过实验确定 (i) 地幔条件下共存橄榄石和瓦兹利石的水饱和度，以及 (ii) 水对 ol-wads 相 P-T-x 坐标的影响。在这些研究的基础上，第二个应用阶段的未来项目将处理（iii）的影响。水对 ol-wads 相变的机制和动力学的影响。