Viscosity of peridotite liquid up to 13 GPa: Implications for magma ocean viscosities
Viscosity of peridotite liquid up to 13 GPa: Implications for magma ocean viscosities
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DOI：
10.1016/j.epsl.2005.10.004
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发表时间：
2005-12
影响因子：
5.3
通讯作者：
C. Liebske;B. Schmickler;H. Terasaki;B. Poe;A. Suzuki;K. Funakoshi;R. Ando;D. Rubie
中科院分区：
文献类型：
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作者：
C. Liebske;B. Schmickler;H. Terasaki;B. Poe;A. Suzuki;K. Funakoshi;R. Ando;D. Rubie
采用同步辐射多顶砧原位落球粘度计研究了高压下橄榄岩液体的粘度。我们使用了一个新设计的胶囊，其中包含一个小的凹进水库的热点以外的加热器，其中的粘度标记球嵌入在镁橄榄石+顽火辉石的混合物具有较高的固相线温度比橄榄岩。该实验装置防止球体在液相线以上的稳定温度建立之前下降，从而避免了从球体通过部分熔融样品下降的速度评估粘度的困难。实验在2.8 ~ 13 GPa、2043 ~ 2523 K温度范围内进行。测量的粘度范围为0.019（±0.004）至0.13（±0.02）Pa s。在恒定温度下，粘度随着压力的增加而增加，最高可达108.5 GPa，但随后在108.5和13 GPa之间降低。粘度的压力依赖性的变化可能与在压缩时发生的液体的结构变化相关联。将我们的结果与最近发表的0.1 MPa橄榄岩液体粘度[D. B.丁韦尔角Courtial，D.佐丹奴，A.尼科尔斯，橄榄岩液体的粘度，地球行星。Sci. Lett. 226（2004）127-138.]，实验数据可以用非阿格尔木的经验Vogel-Fulcher-Tamman方程描述，该方程已经通过增加一个项来解释所观察到的粘度的压力依赖性而被修改。该方程再现了测量的粘度，平均在0.08 log 10单位内。我们用这个模型来计算粘度的橄榄岩岩浆海洋沿着液体的深度为1000公里，并讨论可能的影响粘度在更大的压力和温度比实验研究。
The viscosity of synthetic peridotite liquid has been investigated at high pressures using in-situ falling sphere viscometry by combining a multi-anvil technique with synchrotron radiation. We used a newly designed capsule containing a small recessed reservoir outside of the hot spot of the heater, in which a viscosity marker sphere is embedded in a forsterite+enstatite mixture having a higher solidus temperature than the peridotite. This experimental setup prevents spheres from falling before a stable temperature above the liquidus is established and thus avoids difficulties in evaluating viscosities from velocities of spheres falling through a partially molten sample. Experiments have been performed between 2.8 and 13 GPa at temperatures ranging from 2043 to 2523 K. Measured viscosities range from 0.019 (±0.004) to 0.13 (±0.02) Pa s. At constant temperature, viscosity increases with increasing pressure up to ∼8.5 GPa but then decreases between ∼8.5 and 13 GPa. The change in the pressure dependence of viscosity is likely associated with structural changes of the liquid that occur upon compression. By combining our results with recently published 0.1 MPa peridotite liquid viscosities [D.B. Dingwell, C. Courtial, D. Giordano, A. Nichols, Viscosity of peridotite liquid, Earth Planet. Sci. Lett. 226 (2004) 127–138.], the experimental data can be described by a non-Arrhenian, empirical Vogel-Fulcher-Tamman equation, which has been modified by adding a term to account for the observed pressure dependence of viscosity. This equation reproduces measured viscosities to within 0.08 log10-units on average. We use this model to calculate viscosities of a peridotitic magma ocean along a liquid adiabat to a depth of ∼400 km and discuss possible effects on viscosity at greater pressures and temperatures than experimentally investigated.