Finally, two studies by U.S. workers in the last quadrennium indicate
innovative uses of magnetic fabric for understanding chemical changes
in magnetic minerals. Pick and Tauxe [1991] have
demonstrated with AIR measurements that the magnetic field in
which secondary magnetite precipitates will control the orientation of
the easy axes of the growing grains. Pick and Tauxe observed
both a tendency for the maximum AIR axes to align with the applied
magnetic field and an increase in AIR anisotropy with increasing
magnetic field strength. These results may suggest that anisotropy
of remanence measurements could help identify a secondary
magnetization as a chemical remanence (CRM). In a study of the
Northampton ironstone Hirt and Gehring [1991] found that an
original depositional, but inverse, AMS fabric in siderite was
overprinted in laboratory heating above 250
C by the growth of
secondary magnetite from berthierine, an iron serpentine mineral.
Thus, magnetic fabric measurements can be used to document
chemical changes in magnetic minerals that occur during standard
thermal demagnetization experiments.