| 平极长期漂移与地球平均下地幔黏性估计 |
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| 引用本文： | 杨志根.平极长期漂移与地球平均下地幔黏性估计[J].地球物理学报,2001,44(6):736-746. |
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| 作者姓名： | 杨志根 |
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| 作者单位： | 1. 中国科学院上海天文台,上海,200030;
2. 中国科学院国家天文观测中心,北京100012 |
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| 基金项目： | 国家攀登项目 ( 970 2 31 0 0 3)，上海市科学技术发展基金项目 (JC1 4 0 1 2 )，国家重点基础发展项目
(G1 9980 4 0 70 3) |
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| 摘 要： | 利用9个国际纬度观测站的平纬长期变化序列,重新讨论并估计了平极的长期漂移,得到漂移的平均速率为(3.356“±0.142”)×l0-3/a,方向为西经78.7°±2.5°.进一步基于最新的ICE-4G冰期后地壳反弹模型,采用地球上8个冰盖的冰融参数,估计了理论的平极长期漂移方向为西经74.8°.由观测的平极长期漂移速率为约束,基于1066B地球模型,估计得到地球平均下地幔的黏性为vLM=(0.5-1.7)×1022Pa.s,表明vLM应具有近1022Pa.s量级,并认为地球平极的长期漂移很可能是由最近的21000年以来冰期后的地壳反弹所致.
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| 关 键 词： | 平极长期漂移 冰期后地壳反弹 地球平均下地幔黏性 |
| 文章编号： | 0001-5733(2001)06-0736-11 |
| 收稿时间： | 2000-05-22 |
SECULAR DRIFT OF EARTH'S POLE AND ESTIMATE OF THE MEAN VISCOSITY OF THE LOWER MANTLE |
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| YANG ZHI GEN , Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai\ ,China National Astronomical Observatories,Chinese Academy of Sciences,Beijing\ ,China.SECULAR DRIFT OF EARTH''S POLE AND ESTIMATE OF THE MEAN VISCOSITY OF THE LOWER MANTLE[J].Chinese Journal of Geophysics,2001,44(6):736-746. |
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| Authors: | YANG ZHI GEN Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai\ China National Astronomical Observatories Chinese Academy of Sciences Beijing\ China |
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| Institution: | 1. Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China;
2. National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,China |
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| Abstract: | By using nine long sequences of international latitude observations,the secular drift of the Earth's pole（SDEP） was re estimated. The result shows the drift rate of the Earth's pole is （3.356″ ±0.142″）×10 -3 /a with its direction along west longitude 78.7°±2.5°. Based on the Postglacial rebound （PGR） model ICE 4G,the theoretical direction of drift,74.8°（W）,was obtained by using the parameters of eight ice sheets on the Earth. Under the constraint of the observed SDEP,the mean viscosity of the lower mantle as ν LM =0.5×10 22 -1.7×10 22 Pa·s was estimated. Over the last about million years,the extensive ice complexes over north America and northwestern Europe have repeatedly advanced and retreated with a characteristic period of approximately （1.0-1.2）×10 5 years. In the last deglaciation event beginning 21000 years ago,the total mass of the eight ice sheets discussed in this paper is at least 99.9 percent of all the ice sheet's mass on the Earth. In addition,we note that the mean geographic mass centric position of zone of the PGR on the Earth's surface is at north latitude 61.6° and west longitude 72.4°. Therefore,the estimates of theoretical SDEP and ν LM in this paper can probably be acceptable. |
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| Keywords: | Secular drift of the earth's pole Post glacial rebound Mean lower mantle viscosity of earth |
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