Geoid lineations of 1000 km wavelength over the central Pacific
Geoid lineations of 1000 km wavelength over the central Pacific
复制标题
太平洋中部上空 1000 公里波长的大地水准面线
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
P. Calcagno
中科院分区：
文献类型：
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作者：
A. Cazenave;B. Parsons;P. Calcagno
ERS-1 和 Topex-Poseidon 卫星的高度计剖面已用于计算大地水准面，我们从中提取了太平洋中部上空的中波长大地水准面异常。在该区域，大地水准面显示出幅度为 20-40 厘米的显着拉长异常，间距约为 1000 公里，方向为 N60°W。在太平洋中南部，波利尼西亚热点隆起似乎位于线性大地水准面高点上。然而，后者向东延伸得更远，位于活跃热点之前。在北面，可以看到其他大地水准面线，但它们与已知的构造特征不一致。应用于原始大地水准面数据的小波变换可以清楚地检测到 1000-1200 km 波长的强信号。线纹的幅度随着年龄的增长而增加，在 10 到 50 my 之间增加 3 倍。对年龄和沉积物进行校正的海底地形分析揭示了与大地水准面线状相关的地形异常。导纳和相干性计算给出了 1000-1200 km 波段的高相干性 (0.9)，10 my 处的导纳值为 1.5 m/km，60 my 处的导纳值为 3 m/km。产生线纹的机制尚不清楚。然而，它们的特性与对流起源并不矛盾。
Altimeter profiles of the ERS-1 and Topex-Poseidon satellites have been used to compute a geoid surface from which we have extracted medium-wavelength geoid anomalies over the central Pacific. In this region, the geoid shows prominent elongated anomalies of 20–40 cm in amplitude, with a spacing of ∼1000 km and oriented N60°W. In the south central Pacific, the Polynesian hotspot swells seem to be located on the linear geoid highs. However, the latter extend much farther eastward, preceeding the active hotspots. To the north, other geoid lines are visible but they do not coincide with known tectonic features. The wavelet transform applied to raw geoid data clearly detects a strong signal at the 1000–1200 km wavelength. The amplitude of the lineations increases with age, by a factor of 3 between 10 and 50 my. Analysis of seafloor topography corrected for age and sediments reveals topography anomalies correlated with the geoid lineations. Admittance and coherence calculations give high coherence (0.9) in the 1000–1200 km waveband and admittance values of 1.5 m/km at 10 my and 3 m/km at 60 my. The mechanism producing the lineations is unclear. Their characteristics however are not incompatible with a convective origin.