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华南地区典型岩石的地震波性质研究
Seismic Properties of Typical Rocks in South China
【摘要】 地震资料的解释具有多解性,为根据地震资料认识华南的地壳结构和物质组成,对江西—福建地区的典型岩石样品进行了岩石波速的实验测量和理论计算。使用美国MTS公司815岩石物理参数测试系统测量了5块典型岩石的物性参数。结果表明,岩石的P波和S波速度随着压力的增加而增加,随着温度的增加而降低;在相同温压下,大理岩化灰岩的波速>花岗闪长岩>钾长花岗岩>粉砂岩。由于实验的最大围压为140MPa,测量结果仅能用于约束上地壳浅部的岩石地震波性质。因此,根据岩石的矿物组成、矿物的弹性参数和广义混合律计算了39块样品的波速,为该地区深部地震资料的解释提供依据。随着石英含量的降低,岩石的泊松比和Vp/Vs(P波与S波速度比)都逐渐增高。与长英质岩石相比,灰岩、白云岩和大理石具有高Vp、高泊松比(~0.29)、高Vp/Vs(~1.84)的特征,为通过地震资料在华南花岗岩地区寻找以灰岩为主的深部碳酸盐盆地提供了可能。
【Abstract】 Because the interpretation of seismic data is not unique,seismic properties of typical rock samples from Jiangxi and Fujian Provinces were studied to better explain seismic data in South China in terms of the crustal structure and composition.The P-and S-wave velocities of 5 rock samples were measured using MTS-815 Rock and Concrete Mechanics Test System.The results indicate that seismic velocities of the samples increase with increasing pressure,but decrease with increasing temperature.At the same pressure and room temperature,the P-and S-wave velocities gradually decrease from marbleized limestones,through granodiorites,K-feldspar granites to siltstones.Because the highest confining pressure in the experiments is 140 MPa,the measured velocities are only comparable with seismic observations in the upper crust.To constrain interpretation of seismic data at greater depths,we calculated the seismic velocities of 39 samples based on modal compositions,elastic constants of minerals and generalized mixing rules.The Vp/Vs and Poisson,s ratios of the samples increase with decreasing contents of quartz.Compared with felsic rocks,the limestones,dolomites and marbles are characterized by high P-wave velocities,and high Vp/VS and poisson,s ratios,which provides a way to search carbonate basins beneath the granite regions in South China.
【Key words】 seismic velocities; Poisson,s ratio; granite; limestone; South China;
- 【文献出处】 高校地质学报 ,Geological Journal of China Universities , 编辑部邮箱 ,2011年03期
- 【分类号】P631.4;P584
- 【被引频次】1
- 【下载频次】152