High-temperature transient creep in olivine rocks
High-temperature transient creep in olivine rocks
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DOI：
10.1016/s0040-1951(97)00134-0
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发表时间：
1997-09-30
期刊：
影响因子：
2.9
通讯作者：
Chopra, PN
中科院分区：
文献类型：
--
作者：
Chopra, PN
在高分辨率气体介质变形装置中，研究了两种天然石灰岩在1373 ~ 1573 K温度和300 MPa围压下的瞬态蠕变行为。在恒应力实验中，试样在水相的存在下变形，取向垂直于片理。该结果证实了早期工作人员的发现，即橄榄岩的高温瞬态流动特性可以根据Burgers体流变学有效地建模。卸载后随时间变化的应变恢复进一步支持了这一模型。发现瞬态状态下的粘度（eta(1)）对温度和应力具有相同的敏感性（在每个估计的误差范围内），就像之前发现的稳态蠕变粘度（eta(2)）一样。因此，比值eta(2)/eta(1)对温度和应力相对不敏感，其值在0.17和0.67之间。这些值高于上地幔瞬态变形地球物理模拟中通常假设的eta(2)/eta(1) = 0 1，但与以前橄榄石单晶实验的结果相似。在250 MPa应力和300 MPa围压条件下，瞬态和稳态剪切模量之比mu(2)/mu(1)对温度的敏感性较弱。随着温度的升高，mu(2)/mu(1)的值逐渐减小。本实验0.05 (mu(2)/mu(1)(0.36)，与以往研究报告的取值范围相当。
The transient creep behaviour of two natural dunites has been investigated at temperatures between 1373 and 1573 K and a confining pressure of 300 MPa in a high-resolution gas medium deformation apparatus. The specimens were deformed in constant stress experiments in the presence of an aqueous phase and were oriented perpendicular to foliation. The results confirm the finding of earlier workers that the high-temperature transient flow properties of olivine rocks can be effectively modelled in terms of a Burgers' body rheology. Observations of time-dependent strain recovery after unloading further support this model. The viscosity in the transient regime (eta(1)) is found to have the same sensitivity to temperature and stress (within the errors of each estimate) as has been found previously for steady-state creep viscosity (eta(2)). Thus the ratio eta(2)/eta(1) is found to be relatively insensitive to temperature and stress with values between 0.17 and 0.67. These values are higher than the eta(2)/eta(1) = 0 1 that has generally been assumed in geophysical modelling of upper mantle transient deformation but are similar to the results of previous experiments with olivine single crystals. The ratio of the shear moduli in the transient and steady-state regimes (mu(2)/mu(1)) is found to be weakly sensitive to temperature at 250 MPa stress and 300 MPa confining pressure. The value of mu(2)/mu(1) decreases slowly as temperature increases. For the present experiments 0.05 ( mu(2)/mu(1) ( 0.36 which is comparable to the range of values reported in previous studies.