Deep-Sea Red Clay

a clayey, brown or, more rarely, brick red sediment on the ocean floor. It forms in the pelagic regions of the ocean at depths of more than 4–5 km from a mixture of very fine mineral particles of different composition and origin. In terms of origin, the mineral particles may be terrigenous, volcanic, or authigenic, that is, derived from clayey minerals, iron and manganese hydroxides, zeolites, and other minerals that form on the ocean bottom, primarily as the result of the transformation of volcanic material. The mineral particles also include residual products of the dissolution of biogenic particles. The clay contains admixtures of such biogenic residue as fragments of the bones and teeth of fish, Radiolaria, and foraminifera, as well as meteoric dust.

The chemical composition of deep-sea red clay is distinguished by large amounts of Al, Fe, Mn, Ni, Co, Cu, and Ba and a low organic content. The clay accumulates very slowly, at a rate of 1 mm in 1, 000 years. In the Pacific Ocean about 35 percent of the floor is covered with red clay, and in the Indian and Atlantic oceans, about 25 percent. Iron-manganese concretions are widespread on the surface and within the clay.