影响橄榄石集合体蠕变性质物化因素的研究进展

The Effect of Physical and Chemical Environment on Rheological Behavior of Olivine Aggregates

综述了高温高压条件下岩石和矿物流变性的实验研究结果 ,总结了影响橄榄石集合体流变性能的各种物理和化学因素 .岩石和矿物在高温高压条件下变形的微观机制主要有 2种 :扩散蠕变和位错蠕变 .橄榄石集合体在扩散蠕变机制作用下 ,应变率 ε和差应力之间的关系为线性 ;在位错蠕变机制作用下 ,差应力指数n约等于 3.在相同差应力作用下 ,温度、熔融组分与橄榄石集合体的应变率是正相关的 .含水条件下 ,橄榄石集合体的强度显著降低 .颗粒度对差应力和应变率的影响比较复杂 ,低应变率和小颗粒度对应的差应力指数约等于 1 ;高应变率和粗糙颗粒度时 ,n为 3左右 .

The experimental results of rheological properties of r ocks and minerals were reviewed in this paper. The physical and chemical factors that influence creep behavior of olivine aggregates were discussed in detail. R ocks and minerals have two major micro mechanisms when deformed under high tempe rature and high pressure. One is diffusion creep and the other is dislocation c reep. In the diffusion creep regime, the stress-strain relation is linear and i n dislocation creep regime, the stress-strain relation is power law for olivine aggregates. 100MPa is the transition stress between diffusion creep regime and dislocation creep regime. When the temperature or melt-fraction increases, str ain rate will increase under the same stress level. Water can strongly weaken the st reng th of olivine. Grain size is a complicated factor. Observations suggest that the deformation mechanism in the grain size insensitive regime is dislocation creep, while that in the grain size sensitive regime is diffusion creep.