AVALIAÇÃO DA VARIABILIDADE DAS CONTRIBUIÇÕES RELATIVAS DOS TERMOS HARMÔNICOS ZONAIS EM FUNÇÃO DA TAXA DE REVERSÃO GEOMAGNÉTICA AO LONGO DO FANEROZOICO

Abstract

Assessment of the variability of the relative contributions of zonal harmonic terms as a function of geomagnetic reversal rate throughout the Phanerozoic In this work we aim to investigate, in a wide paleolatitudinal coverage, the variability of the main zonal terms (with respect to the dipolar component) over four geological time intervals with different frequencies of reversal of the polarity of the geomagnetic field - the Cretaceous Normal Superchron (84 - 125 Ma) and the Permo-Carboniferous Reversed Superchron (262 - 318 Ma), magnetozones whose field polarity reversal frequencies tend to zero. In addition to the geological period with a low frequency of reversal of the polarity of the field, the literature presents studies on periods in which the polarity of the geomagnetic field has reversed with higher frequencies, and one of them of special interest in this work: the Permo-Triassic Mixed Polarity Hyperzone (228 - 266 Ma). It was also investigated how dipole contributions occur on a smaller temporal scale, such as in the last 50 thousand years, including observation on an excursion, using field model analysis. Based on selections of directional data from paleomagnetic studies, the development of this study makes it possible to ascertain the fluctuation of non-dipolar components in relation to the dipolar component over time, in different polarity reversal rate intervals, which were a reflection of different geodynamic conditions from Earth's history throughout the Phanerozoic. The results suggested that some features of the geomagnetic field - the quadrupole and octupole - and their behavior contributed to the intensity of the non-dipole field in the different time frames of interest.