Laboratory measurements of vp and vs in a porosity-developed crustal rock: Experimental investigation into the effects of porosity at deep crustal pressures
Laboratory measurements of vp and vs in a porosity-developed crustal rock: Experimental investigation into the effects of porosity at deep crustal pressures
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孔隙度发达的地壳岩石中 vp 和 vs 的实验室测量：深部地壳压力下孔隙度影响的实验研究
DOI：
10.1016/j.tecto.2016.03.044
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发表时间：
2016
期刊：
影响因子：
2.9
通讯作者：
Y.
中科院分区：
文献类型：
--
作者：
Saito;S.;Ishikawa;M.;Arima;M.;and Tatsumi;Y.
为了评估在地壳深部压力下孔隙度对地壳岩石弹性性质的影响，我们进行了实验室测量的压缩波（Vp）和剪切波（Vs）速度在孔隙发育辉长岩样品在室温下高达1.0 GPa。根据测量的VpandVs数据，我们评估了速度、Vp/Vs、泊松比（σ）和岩石总孔隙度随压力的变化。与辉长岩样品的“无孔隙”内禀弹性值相比，我们的结果表明，地壳岩石中孔隙的发展降低了它们的Vp、Vs、Vp/Vs和泊松比。测量值与固有值的偏差（ΔVp、ΔVs、ΔVp/Vs和Δσ）随着孔隙度的增加而增加。我们评估了先前对Tanzawa深成岩体岩石的实验研究中的Δ Vp，为Izu-Bonin-Mariana（IBM）弧的地震速度剖面解释提供了限制，并发现在较低压力下有一个大的负ΔVp（高达-22.7%）。结合在原地压力条件下的速度测量数据，本征速度表明，IBM弧中地壳的Vp（6.0- 6.5km/s）范围反映了中地壳岩石中存在相当大的孔隙及其封闭性和（或）中地壳岩石成分由长英质向中质的变化。
In order to evaluate the influence of porosity on the elastic properties of crustal rocks at deep crustal pressures, we performed laboratory measurements of compressional-wave (Vp) and shear-wave (Vs) velocities in a porosity-developed gabbro sample up to 1.0 GPa at room temperature. Based on the measuredVpandVsdata, we evaluated the changes in velocities,Vp/Vs, Poisson's ratio (σ), and total porosity of the rock as a function of pressure. Compared with the ‘porosity-free’ intrinsic elastic values of the gabbro sample, our results suggest that the development of porosity in crustal rocks lowers theirVp,Vs,Vp/Vs, and Poisson's ratio. Deviations (ΔVp, ΔVs, ΔVp/Vs, and Δσ) of the measured values from the intrinsic values are enhanced with increasing porosity. We evaluated the ΔVpfrom previous experimental study on the rocks of Tanzawa plutonic complex providing constraints on interpretation of the seismic velocity profiles of the Izu–Bonin–Mariana (IBM) arc and found a large negative ΔVp(up to − 22.7%) at lower pressures. The intrinsic velocity combined with the measured velocity data at in situ pressure conditions suggest that the ranges ofVp(6.0–6.5 km/s) in the middle crust of the IBM arc reflect the presence of considerable porosity and its closure in intermediate rocks and/or the change of composition from felsic to intermediate in mid-crustal rocks.