Superparamagnetism and reduction diagenesis in pelagic sediments; enhancement or depletion?

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doi: 10.1029/95GL00888
Author(s): Tarduno, John A.
Author Affiliation(s): Primary:
University of Rochester, Department of Earth and Environmetal Sciences, Rochester, NY, United States
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 22(11), p.1337-1340. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. 16 refs.; illus.
Summary: Superparamagnetic grains, ultra-fine (d < 0.05µm) particles unable to retain a remanence at room temperature, have come under increased scrutiny as indicators of the diagenetic and authigenic history of sedimentary 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, low-temperature, and geochemical studies of pelagic sediments from the western equatorial Pacific Ocean, it is proposed that reduction processes increase rather than deplete the ultra-fine magnetic grain population. At the modern Fe-redox boundary enhanced superparamagnetism coincides with a coarsening of remanence-carrying grains. Superparamagnetism 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 superparamagnetism may help the identification of paleointensity artifacts resulting from non steady-state magnetic mineral reduction. Copyright 1995 by the American Geophysical Union.
Year of Publication: 1995
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Authigenic minerals; Calcareous composition; Cenozoic; Chemical composition; Clastic sediments; Climate effects; Diagenesis; Eh; Grain size; Iron; Leg 130; Magnetic hysteresis; Magnetic intensity; Magnetic susceptibility; Magnetite; Magnetization; Marine sediments; Metals; Natural remanent magnetization; Neogene; ODP Site 806; Ocean Drilling Program; Ontong Java Plateau; Ooze; Oxides; Pacific Ocean; Paleomagnetism; Pelagic sedimentation; Pleistocene; Pliocene; Pore water; Quaternary; Relaxation; Remanent magnetization; Sedimentation; Sediments; Temperature; Tertiary; West Pacific
Coordinates: N001906 N001907 E1592142 E1592140
Record ID: 1995045421
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