Effect of fluid salinity on subcritical crack propagation in calcite
Effect of fluid salinity on subcritical crack propagation in calcite
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DOI：
10.1016/j.tecto.2012.10.023
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发表时间：
2013-01
期刊：
影响因子：
2.9
通讯作者：
F. Rostom;A. Røyne;D. Dysthe;François Renard
中科院分区：
文献类型：
--
作者：
F. Rostom;A. Røyne;D. Dysthe;François Renard
裂纹的缓慢扩展，也称为亚临界裂纹扩展，是造成岩石在地壳条件下韧性变形的一种断裂机制。在本研究中，采用双扭转技术测量了室温下流体化学对方解石单晶裂纹缓慢扩展的影响。延时图像以及力和负载点位移的测量可以在10 - 8至10 - 4m/s的范围内准确表征裂缝速度。得到了不同流体成分、不同NH4Cl和NaCl浓度下的速度随能量释放速率的函数曲线。我们的研究结果表明，流体成分中存在一个阈值，将两种状态分开：裂纹扩展有利的弱化条件和裂纹扩展缓慢的强化条件。我们认为，改变裂纹两个表面之间排斥力的静电表面力可能是造成这种行为的原因。
The slow propagation of cracks, also called subcritical crack growth, is a mechanism of fracturing responsible for a ductile deformation of rocks under crustal conditions. In the present study, the double-torsion technique was used to measure the effect of fluid chemistry on the slow propagation of cracks in calcite single crystals at room temperature. Time-lapse images and measurements of force and load-point displacement allowed accurate characterization of crack velocities in a range of 10−8to 10−4m/s. Velocity curves as a function of energy-release rates were obtained for different fluid compositions, varying NH4Cl and NaCl concentrations. Our results show the presence of a threshold in fluid composition, separating two regimes: weakening conditions where the crack propagation is favored, and strengthening conditions where crack propagation slows down. We suggest that electrostatic surface forces that modify the repulsion forces between the two surfaces of the crack may be responsible for this behavior.