Reflection of P′P′ seismic waves from discontinuities in the mantle
Reflection of P′P′ seismic waves from discontinuities in the mantle
复制标题
P′P′地震波从地幔不连续面的反射
DOI：
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发表时间：
1970
期刊：
影响因子：
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通讯作者：
D. L. Anderson
中科院分区：
文献类型：
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作者：
J. Whitcomb;D. L. Anderson
对地震核心相位 PKPPKP 前兆的走时和视速度的系统研究表明，这些相位是来自地幔的反射。最强的反射来自 630 公里的深度。按照置信度顺序，在 280、520、940、410（非常弱）和 1250 公里（暂定）深度发现了其他反射体。鉴于折射和拉夫波研究表明该深度的速度大幅增加，410 公里反射的弱点令人惊讶。该过渡区域必须比其他区域更宽，或者必须涉及更小的密度跳跃。观察到的反射可能分别来自深度为 50 公里和 130 公里的低速区的顶部和底部。上述反映按照以下固-固相变来解释，按深度增加的顺序：辉石-石榴石固溶体、橄榄石→β尖晶石、β尖晶石→尖晶石和辉石→尖晶石+辉石、尖晶石→后尖晶石、石榴石→钛铁矿或氧化物。 Fe^(2+) 中的自旋-自旋转变可能是其他人发现的更深层次不连续性之一的原因。
A systematic study of the travel times and apparent velocities of precursors of the seismic core phase PKPPKP indicate that these phases are reflections from the mantle. The strongest reflection is from a depth of 630 km. In order of confidence, other reflectors were found at depths of 280, 520, 940, 410 (very weak), and 1250 km (tentative). The weakness of the 410-km reflection was surprising in view of the large velocity increase at this depth indicated by refraction and Love-wave studies. This transition region must be broader than the others or must involve a smaller density jump. Reflections were observed that were possibly from the top and bottom of the low-velocity zone at depths of 50 and 130 km, respectively. The above reflections are interpreted in terms of the following solid-solid phase changes, in order of increasing depth: pyroxene-garnet solid solution, olivine → β spinel, β spinel → spinel and pyroxene → spinel + stishovite, spinel → post-spinel, and garnet → ilmenite or oxides. A spin-spin transition in Fe^(2+) may be responsible for one of the deeper discontinuities found by others.