A rapid method for magnetic granulometry with applications to environmental studies
Abstract
We have developed a rapid method of characterizing the fine-scale variation (sub-micron to hundreds of microns, µm) in the grain size of magnetite in long sediment cores. This method is a new rock magnetic tool and can be readily applied to the following disciplines: (1) environmental studies; (2) hydrology; (3) petrology; and (4) geomagnetism. The method consists of a comparative plot of the depth variation of two magnetic parameters. The first parameter, low field (less than 0.1 millitesla, mT, or 1 Oe) susceptibility in a steady field is plotted on the abscissa. The second parameter, anhysteretic remanent magnetization (ARM) imparted by a smoothly decreasing AF of peak value 100 mT (1,000 Oe) in the presence of a weak steady field (0.01-0.1 mT, or 0.1-1 Oe) is plotted on the ordinate. For a sediment column in which the magnetic mineral is magnetite, a plot of the two magnetic parameters shows transitions in the average magnetic grain size with depth as clearly discernible changes in the slope of a regression line fit to the individual points (χ, ARM).
- Publication:
-
Geophysical Research Letters
- Pub Date:
- April 1981
- DOI:
- 10.1029/GL008i004p00333
- Bibcode:
- 1981GeoRL...8..333B
- Keywords:
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- Geomagnetism and Paleomagnetism: Time variations;
- paleomagnetism;
- Hydrology: Erosion and sedimentation;
- Physical Properties of Rocks: Magnetic and electrical properties;
- General or Miscellaneous: Techniques applicable in three or more fields