D. M. Pecherskya, D. M. Gil’manovab, G. P. Markova, I. O. Murdmaac, D. K. Nurgalievb,
V. A. Tsel’movicha, and Z. V. Sharonovaa
a Schmidt Institute of Physics of the Earth, Russian Academy of Sciences,
ul. Bol’shaya Gruzinskaya 10, Moscow, 123995 Russia
b Kazan Federal University, ul. Kremlyovskaya 18, Kazan, 420008 Russia
c Shirshov Institute of Oceanology, Russian Academy of Sciences, Nahimovskii prospect 36, Moscow, 117997 Russia
e-mail: diamarmpg@mail.com
Received May 23, 2012; in final form, October 9, 2012
Abstract—The thermomagnetic and microprobe analyses of sedimentary samples from DSDP 386, 387, 391A,
and 391C boreholes in the northwestern Atlantic reveal the ubiquitous occurrence of particles of native iron.
The concentrations of native iron are bimodal everywhere with the zero mode necessarily present. The nickel
admixture in native iron forms two groups, one represented by pure iron and the comprising native iron with 5–
6% Ni. The redeposition of iron particles manifests itself in the correlation between the concentrations of these
particles and terrestrial minerals (magnetite), as well as in the equalization and reduction of the concentration
of the iron particles. Pyrite and pyrrhotite are widespread in the studied sediments, and the distribution of native
iron does not depend on the presence of pyrite (i.e., on redox conditions) in them. At the same time, the distri-
butions of pyrite and particles of magnetite + titanomagnetite are inversely correlated, which can probably be
accounted for by the partial dissolution of magnetite and titanomagnetite in the reducing conditions. The
increased concentration of particles of volcanogenic homogeneous titanomagnetite is revealed in the volcano-
clastic turbidites of the Oligocene and early and middle Miocene age at the base of the Bermuda Rise (borehole
386). The titanomagnetite composition is characteristic of the basalts of plume magmatism; it corresponds to
the depth of the magmatic source in the interval of 50–25 km.
DOI: 10.1134/S1069351313020067
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