The impact of water on slip system activity in olivine and the formation of bimodal crystallographic preferred orientations
The impact of water on slip system activity in olivine and the formation of bimodal crystallographic preferred orientations
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水对橄榄石滑移系统活性的影响及双峰晶体择优取向的形成
DOI：
10.1016/j.epsl.2018.12.007
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发表时间：
2019
影响因子：
5.3
通讯作者：
Wilkinson, A.J.
中科院分区：
文献类型：
--
作者：
Wallis, D.;Hansen, L.N.;Tasaka, M.;Kumamoto, K.M.;Parsons, A.J.;Lloyd, G.E.;Kohlstedt, D.L.;Wilkinson, A.J.
橄榄石晶体择优取向被广泛用于推断地幔岩石变形的机制、条件和运动学。最近对水饱和橄榄石的实验首次产生了复杂的CPO，其特征在于[100]和[001]轴的双峰取向分布，并推断由（001）[100]，（100）[001]和（010）[100]滑移的组合活动形成。这一结果可能提供了一个新的微观结构指标的变形存在的浓度升高的晶内水化点缺陷和地震各向异性的解释有影响。在这里，我们记录了一个以前无法解释的自然的例子，这种CPO类型的捕虏体从莱索托和证明，它也可以解释为浓度升高的水化点缺陷。我们测试并证实了假设，结合（001）[100]，（100）[001]，和（010）[100]滑移是形成这种CPO的原因，（1）使用高角分辨率电子背散射衍射精确地识别实验样品和天然样品中存在的位错类型，（2）使用粘塑性自一致的模拟CPO演变，以评估这些滑移系统的能力，以产生所观察到的CPO。最后，我们利用计算的基础上有效介质理论来预测地震波速度的各向异性所产生的CPO捕虏体。横波速度和各向异性的最大值都平行于剪切方向和剪切面法线，而纵波速度的最大值都倾斜，增加了从地震各向异性解释变形运动学的复杂性。
Crystallographic preferred orientations (CPOs) in olivine are widely used to infer the mechanisms, conditions, and kinematics of deformation of mantle rocks. Recent experiments on water-saturated olivine were the first to produce a complex CPO characterised by bimodal orientation distributions of both [100] and [001] axes and inferred to form by combined activity of (001)[100], (100)[001], and (010)[100] slip. This result potentially provides a new microstructural indicator of deformation in the presence of elevated concentrations of intracrystalline hydrous point defects and has implications for the interpretation of seismic anisotropy. Here, we document a previously unexplained natural example of this CPO type in a xenolith from Lesotho and demonstrate that it too may be explained by elevated concentrations of hydrous point defects. We test and confirm the hypothesis that combined (001)[100], (100)[001], and (010)[100] slip were responsible for formation of this CPO by (1) using high-angular resolution electron backscatter diffraction to precisely characterise the dislocation types present in both the experimental and natural samples and (2) employing visco-plastic self-consistent simulations of CPO evolution to assess the ability of these slip systems to generate the observed CPO. Finally, we utilise calculations based on effective-medium theory to predict the anisotropy of seismic wave velocities arising from the CPO of the xenolith. Maxima in S-wave velocities and anisotropy are parallel to both the shear direction and shear plane normal, whereas maxima in P-wave velocities are oblique to both, adding complexity to interpretation of deformation kinematics from seismic anisotropy.
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影响因子：
2
作者：
Prior, DJ
通讯作者：
Prior, DJ
影响因子：
--
作者：
M. Darot;Y. Guéguen
通讯作者：
Y. Guéguen
影响因子：
5.2
作者：
X. Zhong;M. Frehner;K. Kunze;A. Zappone
通讯作者：
X. Zhong;M. Frehner;K. Kunze;A. Zappone
影响因子：
3.1
作者：
Kumamoto, Kathryn M.;Warren, Jessica M.;Hauri, Erik H.
通讯作者：
Hauri, Erik H.
影响因子：
64.8
作者：
T. Mizukami;S. Wallis;J. Yamamoto
通讯作者：
T. Mizukami;S. Wallis;J. Yamamoto