In situ strength measurements on natural upper-mantle minerals
In situ strength measurements on natural upper-mantle minerals
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DOI：
10.1007/s00269-008-0218-6
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发表时间：
2008-02
影响因子：
1.4
通讯作者：
J. Yamamoto;J. Ando;H. Kagi;T. Inoue;A. Yamada;D. Yamazaki;T. Irifune
中科院分区：
文献类型：
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作者：
J. Yamamoto;J. Ando;H. Kagi;T. Inoue;A. Yamada;D. Yamazaki;T. Irifune
利用在压力高达10 GPA和室温400、600和700℃下的原位强度测量，我们研究了地幔包体中包含的橄榄石、斜辉石和铬尖晶石的流变性。用X射线衍射峰的宽度作为压力、温度和时间的函数来估计矿物强度。各矿物的压差应力随压力的增加而增大，但随温度的升高而减小，这是由于加热过程中的压缩弹性应变和应力松弛作用所致。在室温压缩过程中，所有矿物在4-6 Gpa的差应力下都以塑性变形。在随后的加热过程中，在600℃下观察到橄榄石中的热致屈服。斜方辉石和尖晶石都没有表现出完全的应力松弛，但在700℃时两者都保持了一定的应力。在这些条件下，矿物的强度按铬尖晶石、≈、斜辉石和橄榄石的顺序递减。这一强度顺序与地幔包体中流体包裹体的残余压力一致。
Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with the residual pressure of fluid inclusions in mantle xenoliths.