A review of Cenozoic geomagnetic excursions

Driving mechanisms and occurrence frequency of Cenozoic geomagnetic excursions are key questions in geosciences, of which a clear answer might bring about a breakthrough in understanding the behavior of the Earth's core. Researches on geomagnetic excursions mainly focus on the period of Quaternary. Although there are some reports on pre-Quaternary excursions from marine sediments, precise knowledge of timing, duration, and field behavior associated with these excursions are lacking due to the low sedimentation rate of deep-sea sediments. Hereby we made a brief review of past studies on geomagnetic excursions, upon which we sorted out several problems that need to be solved in future study, such as the origin of geomagnetic excursions, the relationship between occurrence timing and paleointensity variation, the age and duration of geomagnetic excursions, and the field behavior during excursions. Learnt from the successful geomagnetic excursion cases in the Quaternary period, future research should focus more on terrestrial fluvial-lacustrine sediments with high sedimentation rates, and it is essential to learn geomagnetic excursion records at different locations. Particularly, tuning paleoclimatic records to shorter orbital parameters such as precession or semi-precession are suggested giving better estimates for the duration of geomagnetic excursions. The tropical and subtropical areas tend to have strong precession or semi-precession signals. It is recommended, therefore, putting these areas as the priority areas to study the details of excursions during the Tertiary.