Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters. Issue 11 (3rd June 2017)

• Record Type: Journal Article
• Authors: Noguchi, A.; Oda, H.; Yamamoto, Y.; Usui, A.; Sato, M.; Kawai, J.
• Is Part Of: Geophysical research letters. Volume 44:Issue 11(2017)
• Page Start: 5360
• Page End: 5367
• Publication Date: 2017-06-03
• Subjects: scanning SQUID microscope -- magnetostratigraphy -- ferromanganese crust -- paleomagnetism -- rock magnetism -- age model; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL073201
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Ferromanganese crusts record long‐term deep‐sea environmental changes. Thus, providing their reliable high‐resolution age models is important. We applied a magnetostratigraphic technique to estimate the growth rate of a ferromanganese crust using scanning SQUID (superconducting quantum interference device) microscope (SSM). SSM is designed to map the magnetic field across thin sections with submillimeter resolution. The crust sample was taken from the Takuyo‐Daigo Seamount, northwestern Pacific, and recorded a limited supply of dust and sediment from continents. After drift correction and removal of spike noises, the magnetic field values were stacked within the areas of high signal‐to‐noise ratios. By correlating the obtained profiles with a standard geomagnetic polarity timescale, we obtained an average growth rate of 3.37 ± 0.06 mm/Ma, which is consistent with that obtained by 10 Be/ 9 Be geochronology (2.93 ± 0.15 mm/Ma). S ratio mapping shows low values after ~3 Ma, associated with voids between columnar structures. Key Points: SQUID microscopy delineated magnetic stripes in ferromanganese crust parallel to growth layers indicating a growth rate of 3.37 mm/Ma Magnetic minerals may be oxidized magnetites of low and medium coercivities with high‐coercivity minerals such as hematite or goethite S ratio shows heterogeneous distribution of high‐coercivity minerals younger than 3 Ma associated with voids between columnar structures