Dictionary of Geotourism

2020 Edition
| Editors: Anze Chen, Young Ng, Erkuang Zhang, Mingzhong Tian

Magnetostratigraphic Polarity Unit

Reference work entry
DOI: https://doi.org/10.1007/978-981-13-2538-0_1491

A magnetostratigraphic polarity unit is a stratigraphic unit subdivided according to the variations (e.g., reversals, deviations) of the remnant magnetization in the rock strata. At the time of formation, a rock is magnetized in the same direction as the Earth’s magnetic field, and these magnetic properties are recorded in the rock. Over geologic tine, the polarity of the Earth’s magnetic field has changed and reversed. Hence, the direction of the remnant magnetic polarity recorded in a stratigraphic sequence can be used as the basis for subdividing the sequence into units characterized by their magnetic polarities, which are called magnetostratigraphic polarity units. The time interval represented by a magnetostratigraphic unit is called a ‘magnetic chron’ or ‘magnetozone’. For example, the Institute of Geomechanics, Chinese Academy of Geological Sciences, has categorized the Quaternary Period from top to bottom into the ‘Brunhes normal chron’, ‘Matuyama reverse chron’, ‘Gauss normal...

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