Paleomagnetic and Be-isotope age of the ferromanganese crust in the Western Pacific

Abstract

Age of ferromanganese crust obtained in the Western Pacific (~20 °N) was estimated by paleomagnetic measurements, Be-isotope and Co concentration. Magnetic measurements were performed after Oda et al. (2011) using a superconducting quantum interference device magnetometer (SSM). Natural remanent magnetization perpendicular to the growth lamella of the crust samples shows more than 30 ancient geomagnetic field reversals down to the depth of ~ 40 mm. Comparison with the reference geomagnetic time scale reveals ~10 Ma, indicating an average growth rate of ~4 mm/Myr. Be-isotope dating also presents a similar result showing 8.22 Ma at the depth of ~30 mm. interference device magnetometer (SSM). Natural remanent magnetization perpendicular to the growth lamella of the crust samples shows more than 30 ancient geomagnetic field reversals down to the depth of ~ 40 mm. Comparison with the reference geomagnetic time scale reveals ~10 Ma, indicating an average growth rate of ~4 mm/Myr. Be-isotope dating also presents a similar result showing 8.22 Ma at the depth of ~30 mm.