Gravity and bathymetry in the central Pacific Ocean
Gravity and bathymetry in the central Pacific Ocean
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DOI：
10.1029/jb081i008p01533
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发表时间：
1976-03
影响因子：
--
通讯作者：
A. Watts
中科院分区：
文献类型：
--
作者：
A. Watts
在夏威夷地区的太平洋中部，海面舰船和海底摆重力测量结果被汇编成一张新的自由空气重力异常图。该地图的主要特征是夏威夷山脊上方的大振幅正异常（高达+700 mGal），山脊两侧的大振幅负异常（高达- 136 mGal），以及与负异常相邻的宽带（>250 km）正异常（+25至+50 mGal）。该地图已用于构建1°×1°，5°×5°和10°×10°的自由空气异常平均值。5°×5°平均图的主要特征是夏威夷脊东南端的长波长（~ 2200 km）正异常（高达+15 mGal）。在10°×10°平均图上也可以看到长波正异常，这与Gem 6卫星导出的调和度16的解非常吻合。计算表明，夏威夷海脊的地壳结构不太可能对这些长波长正异常有显著贡献。正异常与夏威夷脊叠加的夏威夷涌浪密切相关。回归线分别表示1°×1°和5°×5°重力对地形坡度的平均值，分别为21 mGal/km和22 mGal/km。这些斜坡比其他岩石圈扭曲了很远的地方的斜坡要小，这表明如果膨胀被扭曲了，它必须得到补偿。补偿的形式是不确定的，但它可能与岩石圈下的某种流动模式有关，这种流动模式既维持了膨胀，又维持了相关的长波重力异常。
Surface-ship and submarine pendulum gravity measurements have been compiled in a new free air gravity anomaly map of the central Pacific Ocean in the region of Hawaii. The main features of the map are large amplitude positive anomalies (up to +700 mGal) over the Hawaiian ridge, large amplitude negative anomalies (up to −136 mGal) flanking the ridge, and a broad belt (>250 km) of positive anomalies (+25 to +50 mGal) bordering the negative anomalies. The map has been used to construct 1°×1°, 5°×5°, and 10°×10° free air anomaly averages. The main feature of the 5°×5° average map is a long-wavelength (∼2200 km) positive anomaly (up to +15 mGal) over the southeastern end of the Hawaiian ridge. A long-wavelength positive anomaly is also seen on the 10°×10° average map, which agrees well with the Gem 6 satellite-derived solution to harmonic degree 16. Computations suggest that crustal structure of the Hawaiian ridge is unlikely to contribute significantly to these long-wavelength positive anomalies. The positive anomalies correlate closely with the Hawaiian swell upon which the Hawaiian ridge is superimposed. The regression lines representing 1°×1° and 5°×5° averages of gravity against topography slope at 21 mGal/km and 22 mGal/km, respectively. These slopes are smaller than those over other regions where the lithosphere is warped for large distances, suggesting that if the swell is warped, it must be compensated. The form which the compensation takes is uncertain, but it may be related to some pattern of flow beneath the lithosphere which maintains both the swell and the associated long-wavelength gravity anomalies.