Paleointensity variations around 30 Ma estimated from successive lava flows of the Afro-Arabian Large Igneous Province
Abstract
The reconstruction of continuous paleointensity records during geomagnetic polarity reversals is fundamentally important for understanding the nature of the geomagnetic field during reversals. Therefore, we conducted a paleointensity study on volcanic rocks in the Afro-Arabian Large Igneous Province (AALIP), which is claimed to have erupted and formed at about 30 ± 0.4 Ma. We used four block samples collected from each of 93 lava flows. The samples whose thermomagnetic curves indicative of low-temperature oxidation and more than 30% difference between heating and cooling curves were not used for paleointensity measurements. In addition, the bulk domain stability (BDS) (Paterson et al., 2017) was calculated from the hysteresis data, and samples that have BDS values below the threshold of 0.1 were excluded. In order to recover successive paleointensity variations, relative paleointensity (RPI) was calculated for 113 samples of 56 flows based on NRM/ARM slope (Tauxe et al., 1995). RPIs ranging from 0.037 to 4.9 were obtained from 106 samples of 52 flows. The average of the flow mean calculated from three independent RPI values is 1.4 ± 1.0 (N=6). The correlation between the RPIs and absolute paleointensities estimated using the Tsunakawa-Shaw method (Tsunakawa and Shaw, 1994; Yamamoto et al., 2003) at the sample level was R=0.82. A bi-plot of the VGP latitudes and the RPIs shows a U-shaped distribution; RPIs are low when VGPs are in middle to low latitudes. This is similar to the relationship between RPI and VGP latitude in Oligocene shown by Tauxe and Staudigel (2004).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGP41A0773Y
- Keywords:
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- 1513 Geomagnetic excursions;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1521 Paleointensity;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1522 Paleomagnetic secular variation;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1535 Reversals: process;
- timescale;
- magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM