Shape of Fe-Ni grains and magnetic susceptibility anisotropy in Antarctic chondrites
Abstract
Magnetic susceptibility anisotropy is measured for various petrologic types of ordinary chondrites from Antarctica, which are of three H types, four L types and four LL types. Three of the four LL types are shock-melted chondrites of high strength while the fourth has very low strength. Magnetic susceptibility anisotropy appears to be low for LL chondrites and seems to bear no correlation with porosity and petrologic types among H and L chondrites. Both prolate and oblate susceptibility ellipsoids are obtained. To characterize the shape irregularity of metallic grains, the Fourier descriptors representation with an arc-length coordinate system is introduced for a two-dimensional outline of grains. Unlike the normally used polar coordinate system, this method is applicable to any complicated shape of grain boundary. Advantages of the method are demonstrated for selected Fe-Ni grains.
- Publication:
-
National Institute Polar Research Memoirs
- Pub Date:
- December 1983
- Bibcode:
- 1983PolRe..30..389F
- Keywords:
-
- Chondrites;
- Magnetic Permeability;
- Meteoritic Microstructures;
- Antarctic Regions;
- Fourier Series;
- Grain Boundaries;
- Iron;
- Nickel;
- Petrology;
- Lunar and Planetary Exploration