Estimating polarity reversal rate through cyclostratigraphy analysis in the Avellaneda Formation (~570 Ma), La Providencia Group, Argentina

Abstract

The behavior of the Earth’s magnetic field during the Ediacaran Period (635-542 Ma) is intriguing. Paleomagnetic data suggest a hyperactive state characterized by a high frequency of polarity reversals and an apparent ultra-low field strength. These unusual activities seem likely to extend until the Ediacaran-Cambrian boundary, however, the scarcity of data hampers our comprehension from this hyperactive mode and field behavior remains unknown. Here, we use magnetostratigraphy data previously obtained in two drill cores from the Avellaneda Formation and combine with new cyclostratigraphy results to provide a reversal frequency time calibrated using clostratigraphy. The cyclostratigraphic study identified several orbital periods including the 100 kyr short eccentricity. This allows us to quantify the reversal frequency n the Avellenda Formation and our estimates range of 7–11 R/Ma (reversals per million years). This result is close to those documented in coeval Ediacaran units positioned nearby Shuram isotope excursion. So, these results appear to be in agreement with high reversal frequency around ~570 Myr. The acquisition of new cyclostratigraphy data in Avellaneda Formation is strongly recommended and can be critical to understanding the behavior of the Earth’s geomagnetic field in Ediacaran-Cambrian transition.