Electrical Conductivity Anomaly and Terrestrial Heat Flow
Electrical Conductivity Anomaly and Terrestrial Heat Flow
复制标题
电导率异常和大地热流
DOI：
10.5636/jgg.22.75
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
T. Rikitake
中科院分区：
文献类型：
--
作者：
S. Uyeda;T. Rikitake
短周期地磁异常有两种类型：一种是高切ΔZ型，其特征是ΔZ高频分量的高衰减；另一种是定向变化型，其特征是变化向量的异常方向性。“高切度ΔZ型”异常预计出现在导电层凸起的区域，“定向变异型”异常预计出现在不同电性区域之间的边界。将世界各地报道的地磁异常分为上述两类，并与地球热流观测结果进行比较。“高切度ΔZ型”异常多与高热流有关，而“定向变型”异常多与高、低热流区边界有关。这种相关性是根据上地幔的温度分布来解释的。在大陆边缘发现了典型的“定向变化型”异常，在那里海水的影响不应被忽视。进一步表明，从热流和电导率异常的角度来看，大陆边缘有两种类型：正常（大西洋型）和岛弧型（太平洋型）大陆边缘。最后，对日本中部异常提出了一个较为合理的模型，该异常的复杂性至今仍无法从理论上解释：日本中部异常是由半岛效应叠加和本州西南菲律宾海沿岸地区高导层波动引起的，该地区海中热流高于陆中热流。与本州东北部不同，本州西南部不是典型的岛弧。
There are two types in anomalies of short period geomagnetic variations: one (High cut ΔZ type) is characterised by high attenuation of high frequency components of ΔZ and the other (Directional variation type) by unusual directionality in the variation vector. “High-cut ΔZ type” anomaly is expected to be found in areas where the electrically conducting layer is raised and “Directional variation type” is expected to exist at boundaries between areas having different electrical properties. Reported anomalies of geomagnetic variations in various parts of the world are classified into the above two types and compared with the observations of terrestrial heat flow. Most of “High-cut ΔZ type” anomalies are associated with high heat flow, whereas most of “Directional variation type” anomalies are associated with the boundaries of high and low heat flow areas. Such correlations are interpreted in terms of the temperature distribution in the upper mantle. Typical of “Directional variation type” anomalies are found at continental margins, where the effect of sea water should not be overlooked. It is further shown that, from the view-point of both heat flow and the conductivity anomaly, there are two types in continental margins: normal (Atlantic type) and island arc type (Pacific type) continental margins. Finally, a model that appears reasonable is presented for Central Japan anomaly of which complex nature so far rejected theoretical interpretations: Central Japan anomaly is caused by the superposition of peninsula effect and undulation of high conductive layer under the Philippine Sea coastal area of southwestern Honshu where heat flow is higher in the sea than in the land. Unlike northeastern Honshu, southwestern Honshu is not a typical island arc.