Open AccessA comparative study of the ARM and I sr of some natural magnetites of MD and PSD grain size
Author(s) -
Hartstra R. L.
Publication year - 1982
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1982.tb05999.x
Subject(s) - magnetite , maghemite , geology , grain size , remanence , mineralogy , natural remanent magnetization , homogeneous , materials science , magnetization , magnetic field , thermodynamics , physics , paleontology , quantum mechanics , geomorphology
Summary. ARM and I sr stability with respect to alternating field and low‐temperature treatment were measured for a set of artificial rock specimens. Each of the specimens contained a known amount of a natural magnetic mineral of a known grain size. The following minerals were used: a homogeneous natural magnetite, a natural titanomagnetite with submicroscopic Fe‐rich inclusions, and a natural titanomagnetite and a natural titano‐maghemite that both show exsolution phenomena. The grain size of the fractions varied from < 5 to 250 μm. It is found that the stability of ARM and I rs of multi‐domain grains with respect to alternating fields and low‐temperature treatment is similar, whereas for the smallest grains studied (< 5 μm) ARM is more stable than I sr . Multi‐domain ARM data from this study are in agreement with current multi‐domain ARM theory. Low‐temperature behaviour of ARM and I sr can be explained either in terms of a model in which stable moments in the bulk of the grains are screened by the surrounding matrix or in terms of a model in which regeneration of the bulk remanence plays a role and in which stable moments are situated on the surfaces of the grains.