Abstract The Cretaceous Normal Superchron constitutes an enigmatic ∼37‐Myr interval of stable polarity in the history of the Earth’s magnetic field. The strength of the geomagnetic dipole moment during this interval is controversial, with absolute paleointensity determinations on crystallized volcanic rocks, volcanic glasses, and silicate crystals yielding statistically different averages. In this study, we present the first paleointensities in the mid of the superchron conducted on baked sediments from Hainan (SE Asia). This hitherto underexploited material, akin to baked clays used in archeomagnetism, produces unambiguous linear Arai‐Nagata diagrams over 60%–90% of the fraction of natural remanent magnetization. Using strict selection criteria, we show that baked sediments, volcanic glasses, and silicate crystals are consistent with a dipole moment ∼40% higher than the present‐day value. Relying on 22 independent determinations only, this combined data set leaves open the question of the dependency between geomagnetic dipole strength and reversal frequency.
Observations from the Little Bunker
Last updated: October 16, 2025 02:57 AM
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