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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Influence of water on plastic deformation of olivine aggregates 1. Diffusion creep regime
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Influence of water on plastic deformation of olivine aggregates 1. Diffusion creep regime

机译：水对橄榄石骨料塑性变形的影响1.扩散蠕变状态

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The influence of water on diffusion creep of olivine aggregates was investigated by performing high-temperature creep experiments under both hydrous acid anhydrous conditions. Deformation experiments were conducted on fine-grained samples using a gas medium apparatus at confining pressures of 100 to 450 MPa and temperatures between 1473 and 1573 K. Water was supplied by the dehydration of talc, which occurs near 1075 K. Water fugacities of similar to 85 to 520 MPa were obtained by varying the confining pressure under water-saturated conditions. Under both hydrous and anhydrous conditions deformation was dominated by grain boundary diffusion. At a water fugacity of similar to 300 MPa, samples crept similar to 5 times faster than those deformed under anhydrous conditions at similar differential stresses and temperatures. Within the range of water fugacity investigated, the strain rate is proportional to water fugacity to the 0.7 to 1.0 power, assuming values for the activation volume of 0 to 20 x 10(-6) m(3)/mol, respectively. We propose the following point defect model to explain this water-weakening effect: in going from an anhydrous to a hydrous environment the charge neutrality condition changes from [Fe-Me(.)] = 2 [V-Me"] to [Fe-Me(.)] = [H-Me']. As a consequence, for olivine aggregates the concentration of silicon interstitials, the rate of silicon diffusion, and therefore the rate of diffusion creep increase systematically with increasing water fugacity (i.e., OH concentration). [References: 71]
机译：通过在两种含水酸无水条件下进行高温蠕变实验，研究了水对橄榄石聚集体扩散蠕变的影响。使用气体介质设备在100至450 MPa的限制压力和1473至1573 K的温度下，对细粒样品进行了变形实验。滑石粉的脱水提供了水，这发生在1075 K附近。通过在水饱和条件下改变围压来获得85至520MPa。在含水和无水条件下，变形都以晶界扩散为主。在大约300 MPa的水逸度下，样品的蠕变速度比在相同的压差和温度下在无水条件下变形的样品快5倍。在研究的水逸度范围内，应变率与水逸度成比例，与0.7至1.0的幂相关，假定激活体积的值分别为0至20 x 10（-6）m（3）/ mol。我们提出以下点缺陷模型来解释这种弱化水的效果：在从无水变为含水环境时，电荷中性条件从[Fe-Me（。）] = 2 [V-Me“]变为[Fe- Me（。）] = [H-Me']。因此，对于橄榄石聚集体，硅间隙的浓度随着水逸度（即OH浓度）的增加，硅的扩散速率以及扩散蠕变速率会系统地增加。 ）。[参考：71]

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