Terrigenous Sedimentation on the Submarine Shirshov Ridge (Bering Sea) during the Last Deglaciation

Lithology and Mineral Resources - The submarine Shirshov Ridge is an independent system of terrigenous sedimentation, which is geomorphologically isolated from bottom terrigenous influx into the...     

Sedimentary infill in the equatorial Mid-Oceanic Canyon,Atlantic Ocean

Facts confirming the hypothesis of contourite sediment infill of the Equatorial Mid-Ocean Canyon (EMOC) are presented. We examined two cores recovered in Cruises 37 and 43 of the R/V Akademik Ioffe (2012, 2013). The cores recovered upper Quaternary miopelagic clays on the EMOC floor (AI-3149) and the adjacent abyssal plain (AI-2620). The study of these cores unraveled significant differences in their composition. In contrast to the lithologically homogeneous Core AI-2620, Core AI-3149 includes interlayers enriched in the biogenic CaCO₃, terrigenous silt, and authigenic ferromanganese micronodules. These peculiarities are attributed to activity of the Antarctic Bottom Water (AABW) contour currents along the EMOC.     

Iron and Manganese Minerals in Suspended Matter from the Barents Sea

The mineralogy of suspended matter from surface and bottom waters is studied at two sites in the Barents Sea. Along with terrigenous minerals, the suspended matter samples contain authigenic mineral phases of iron and manganese oxyhydroxides. Mn-feroxyhite, Fe-vernadite, goethite, and proto-ferrihydrite were identified in samples from surface waters, whereas birnessite and nonferruginous vernadite were registered in samples from bottom waters. The formation of suspended manganese minerals in bottom waters is explained by an additional Mn supply from underlying reduced sediments during their early diagenesis and oxygen depletion in the near-bottom nepheloid layer. Bacteria are supposed to take part in the authigenic mineral formation.     

History of sedimentation in Isfjord (Western Spitsbergen)

Lithology, heavy mineral associations, and chemical composition of sediments studied in two gravity cores from Isfjord, Western Spitsbergen, accompanied by high-frequency seismic records, provide a new insight on the provenance and glaciomarine sedimentation in the fjord from the last deglaciation through the Holocene.