Abstract
The empirical observation is made that marginal seas which have spread orthogonal to their margins have clearly defined lineated magnetic anomaly patterns, while marginal seas which have spread at acute angles to their margins have chaotic or subdued magnetic anomaly patterns.
Deep ocean basins which have acute angles between their margins and their spreading directions generate magnetic patterns that are also chaotic (magnetic quiet or smooth zones), due to a geometrically controlled MOR structure consisting of many small spreading-segments connected by many small-offset FZ. Magnetization of such a complex structure by reversals of the Earth's magnetic field produces a magnetic pattern having many small magnetic domains juxtaposed, half with normal and half with reversed polarity. The FZ offsets cause blocks of one polarity to be surrounded on all sides by blocks of opposed polarity, and both their small size and close proximity results in sea-surface magnetometers recording magnetically subdued or chaotic area.
Marginal sea basins having margins acutely angled to the spreading direction, can also be explained as ‘structural magnetic quiet zones’.
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Roots, W.D. Chaotic magnetic patterns in marginal seas and small ocean basins have similar origin to structural magnetic quiet zones in deep oceans. Mar Geophys Res 8, 383–389 (1986). https://doi.org/10.1007/BF02084020
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DOI: https://doi.org/10.1007/BF02084020