Palaeosecular variation, field reversals and the stability of the geodynamo in the Precambrian.

Palaeosecular variation (PSV), as estimated from the scatter of remanent magnetization directions or poles, can be used to shed light to processes in the geodynamo, and potentially, to model the growth of the solid inner core. To understand the temporal aspects of the geomagnetic field behavior in the far past, we have calculated the scatter of palaeomagnetic poles (S) from a set of 55 high-quality observations derived from a new Precambrian paleomagnetic data compilation. Our analysis supports former Phanerozoic and Precambrian analyses of PSV, which favour a lower reversal rate, a higher stability of the geodynamo and a substantially smaller size of the inner core prior to 1.5 billion years ago. [ABSTRACT FROM AUTHOR]