ESTIMATING POLARITY REVERSAL RATE THROUGH CYCLOSTRATIGRAPHY ANALYSIS IN THE AVELLANEDA FORMATION (~570 MA), LA PROVIDENCIA GROUP, ARGENTINA

AFONSO, J.W.L.; RAYSA MAGALHÃES ROCHA; DANIEL RIBEIRO FRANCO; NATÁLIA BRAUN DOS SANTOS; FRANCESCHINIS, PABLO R.; RAPALINI, AUGUSTO E.; ARROUY, MARIA JULIA; GÓMEZ PERAL, L.E.; POIRÉ, D.G.; TRINDADE, R.I.F.

Río de Janeiro

Congreso; LatinMag VII Biennal Meeting; 2023

Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo

The behavior of the Earth's magnetic field during the Ediacaran Period (635-542 Ma) isintriguing. Paleomagnetic data suggest a hyperactive state characterized by a highfrequency of polarity reversals and an apparent ultra-low field strength. These unusualactivities seem likely to extend until the Ediacaran-Cambrian boundary, however, thescarcity of data hampers our comprehension from this hyperactive mode and fieldbehavior remains unknown. Here, we use magnetostratigraphy data previouslyobtained in two drill cores from the Avellaneda Formation and combine with newcyclostratigraphy results to provide a reversal frequency time calibrated usingclostratigraphy. The cyclostratigraphic study identified several orbital periods includingthe 100 kyr short eccentricity. This allows us to quantify the reversal frequency in theAvellenda Formation and our estimates range of 7–11 R/Ma (reversals per millionyears). This result is close to those documented in coeval Ediacaran units positionednearby Shuram isotope excursion. So, these results appear to be in agreement withhigh reversal frequency around ~570 Myr. The acquisition of new cyclostratigraphydata in Avellaneda Formation is strongly recommended and can be critical tounderstanding the behavior of the Earth's geomagnetic field in Ediacaran-Cambriantransition.