13. MAGNETIC HYSTERESIS PROPERTIES OF FINE-GRAINED MAGNETIC IRON SULFIDE NODULES AND CRUSTS ON THE AMAZON FAN¹

Frank R. Hall,² Stanley Cisowski,³ and John W. King⁴

ABSTRACT

The sediments from Ocean Drilling Program Leg 155 included authigenic magnetic-mineral phases. Four iron sulfide nodules, up to 5 cm³ in volume, and a single iron sulfide crust (~2 cm³) were analyzed for magnetic hysteresis properties. The results indicate that these authigenic minerals are fine grained and behave as single-domain sized particles. Camera X-ray diffraction and chemical analyses using the scanning-electron microscope indicate that the authigenic minerals are composed of greigite (Fe₃S₄).

¹Flood, R.D., Piper, D.J.W., Klaus, A., and Peterson, L.C. (Eds.), 1997. Proc. ODP, Sci. Results, 155: College Station, TX (Ocean Drilling Program).
²College of Marine Studies, University of Delaware, Newark, DE 19716, U.S.A. frhall@udel.edu
³Department of Geological Sciences, University of California, Santa Barbara, CA 93103, U.S.A.
⁴Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, U.S.A.