Magnetic reversal frequency in the Lower Cambrian Niutitang Formation, Hunan Province, South China.

The reversal frequency of the palaeomagnetic field bears great information of evolution of Earth's deep interior. However, there are still debates on the frequency pattern during the older periods of the Phanerozoic. This study investigated the Niutitang Formation (Lower Cambrian) of the Ciye 1 Hole from South China. Rock magnetic results indicate that the dominant magnetic carrier is magnetite. Characteristic remanence magnetizations have been successfully isolated for the weakly magnetized shale rocks through stepwise alternated field demagnetization using the 2G Enterprises Rapid System Magnetometer with a low-noise thin-walled quartz-glass sample holder. Constrained by radiometric ages, our palaeomagnetic results indicated frequent polarity reversals during the period of ∼524–514 Ma, which backs up the speculation about the episode of the Ediacaran–Cambrian (∼550–500 Ma) with a character of reversal hyperactivity. [ABSTRACT FROM AUTHOR]