Paleointensity of the geomagnetic field in the last half-million years in regions of the Red Sea and south of the Mid-Atlantic Ridge

The paleointensity of a geomagnetic field is determined on the basis of the standard Thellier’s method using the remanent magnetization ($H_a$) of basalts of the rift zone of the Red Sea (with an age of 0.5 million years) and south of the Mid-Atlantic Ridge (with an age of 0.1–0.3 million years). Samples were selected whose natural remanent magnetization (NRM) was mainly one-component and the measured Curie temperatures of the titanium-magnetite fraction ($T_C=205$-250$^0$C) were close to the calculated values. Samples with $T_C\approx580$$^0$C were also used. It was shown that NRM of basalts with both high and low $T_C$ values have a thermoremanent nature. The studies have revealed that the law of independence and additivity of partial thermoremanent magnetizations (PTRMs) is satisfied for the collected samples with an error of no more than 6% and the error of determination of the field of TRM creation using the Arai-Nagata diagram is no more than 10%. The value $H_a=32$ A/m determined from NRM of basalts south of the Mid-Atlantic Ridge appears to be approximately equal to the contemporary intensity of the geomagnetic field ($H_E$) in this region. In the Red Sea region, $H_a=77.5$ A/m, which is 2.5 times higher than the current value. It is suggested that during formation of the basalts of the Red Sea rift zone the geomagnetic pole was located in that region and the virtual dipole moment was 35% higher than its contemporary value.