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Abstract

We conducted a comprehensive paleomagnetic study on the Paraná-Etendeka Igneous Province (PEIP) in southern Brazil, which is approximately 135 million years old. The study aimed to expand the scarce southern hemisphere paleomagnetic database. We recovered twelve paleomagnetic sites from basaltic lava flows, which were erupted between 131.5 and 135.6 million years ago. Before accepting the results for paleointensity analyses, we tested the reliability of the rock magnetism data. The Thellier-Coe paleointensity protocol was used to analyze 109 specimens from all the studied sites. After passing the quality criteria, we selected 26 individual samples from nine sites to test the consistency of the paleointensity determinations. The new high-quality mean paleointensity value is 30.6±7.2µT, corresponding to a virtual dipole moment (VDM) of 5.75 ± 0.49 x 1022 Am2. These values suggest that the Earth's magnetic field strength was slightly elevated compared to the long-term average geomagnetic field that prevailed during the Cretaceous Normal Superchron, accounting for approximately 72% of the present-day Earth's magnetic field. We also calculated the paleomagnetic pole, which had an angular difference of 22° in declination and 5° in inclination with respect to the expected pole. This difference may correspond to secular variation, considering the confidence cones. Our results were compared with previous paleomagnetic data to approach the accuracy of recent models for the Cretaceous interval. This study contributes to the expansion of the southern hemisphere paleomagnetic database and provides new insights into the Earth's magnetic field strength during the Cretaceous Normal Superchron.