Ja. Tarduno, SUPERPARAMAGNETISM AND REDUCTION DIAGENESIS IN PELAGIC SEDIMENTS - ENHANCEMENT OR DEPLETION, Geophysical research letters, 22(11), 1995, pp. 1337-1340
Superparamagnetic grains, ultra-fine (d < 0.05 mu m) particles unable
to retain a remanence at room temperature, have come under increased s
crutiny as indicators of the diagenetic and authigenic history of sedi
mentary rocks. In marine sediments, fine-grained magnetite with large
surface area to volume is thought to be preferentially removed during
magnetic mineral reduction. On the basis of new magnetic hysteresis, l
ow-temperature, and geochemical studies of pelagic sediments from the
western equatorial Pacific Ocean, it is proposed that reduction proces
ses increase rather than deplete the ultra-fine magnetic grain populat
ion. At the modern Fe-redox boundary enhanced superparamagnetism coinc
ides with a coarsening of remanence-carrying grains. Superparamagnetis
m also tracks proposed temporal changes in magnetite reduction caused
by climatically-driven fluctuations in organic carbon (C-org) supply.
Together with hysteresis characteristics, changes in superparamagnetis
m may help the identification of paleointensity artifacts resulting fr
om non steady-state magnetic mineral reduction.