Reconstruction of the conditions of Late Holocene sedimentation by integrated analysis of a core of the bottom sediments from the Chukchi Sea

Integrated studies were performed on bottom sediments collected in the Chukchi Sea in the northern part of the Gerald Canyon 150 km northeast from Wrangel Island. The recent sedimentation rate amounted to 0.9 mm/year by ²¹⁰Pb at the sampling site. The concentrations of biogenic components (SiO_2bio, С_org, N_tot, and Br) were minimum at the lower part of the core, where an increase of Thalassiosira antarctica antarctica, probably results from low biological productivity during the Maunder Minimum. The increased concentrations of biogenic components, as well as the decreased values of magnetic susceptibility and X-ray density, in the upper part of the core (1–2 cm) correspond to the last decade of recent of global warming.     

The First Find of Goethite Crusts in the Sea of Japan

Doklady Earth Sciences - Ferruginous (goethite) mixed-type hydrothermal–hydrogenetic crusts, which were found in the Sea of Japan for the first time, are described. Compared to manganese...     

The First Colorimetric Characteristic of Bottom Sediments from the Chukchi Sea

Doklady Earth Sciences - The quantitative characteristics of the bottom sediment color of the Chukchi Sea is presented. The correlation relationships with the contents of grain-size fractions,...     

Overlapping Ore Mineralization of Volcanic Rocks from the Sea of Japan: New Data

Doklady Earth Sciences - Semi-quantitative and qualitative analyses of the overlapping (postvolcanic) ore mineralization of the main volcanic rock types that compose submarine rises in the Sea of...     

Seasonal—daily variations in the electromagnetic background of the medium-frequency and high-frequency radio ranges during low solar activity

Based on the data of the long-term monitoring of the electromagnetic background at frequencies of 1–30 MHz in Tomsk, new main regularities of the daily and seasonal variations in this background in different frequency ranges at a low level of solar activity (the annual average values are 68.6 = F _10.7 <= 80.9) have been established.     

Implications of Color and Lightness Characteristics for Lithostratigraphy of Bottom Sediments from the Chukchi Plateau,Arctic Ocean

Marine sediment cores from the Chukchi Plateau are used to demonstrate the efficiency of digital photographic determination of sediment color and lightness, supplemented with the statistically processed data on sediment composition, for lithostratigraphy and paleoreconstructions. Several clusters were established that correspond to brown and gray sediment layers, carbonate-rich beige interlayers and specific segments of unclear lamination and/or lens-like intercalation of brownish and grayish beds. Correlation of the studied cores with other sediment cores from the region with well-established stratigraphy revealed good correspondence (though with certain specific features) to the conventional model of the Late Pleistocene–Holocene sediment accumulation in the offshore Arctic Ocean beyond shelf areas with clearly defined glacial–interglacial cyclicity. It was shown that enhanced red-color component corresponds to the enrichment of the interglacial brown sediment layers with manganese and accompanying elements. Glacial gray layers with enhanced green-color component are enriched in iron, as well as rubidium, vanadium, titanium and yttrium and bear evidence for considerable diagenetic transformations. Blue-color component is related to the high calcium content (carbonate rock fragments) in the carbonate-rich interlayers accumulated during the periods of active disintegration of continental ice sheets and iceberg-rafting of terrigenous lithic fragments. Intermediate values of the studied parameters are likely indicative of specific sedimentation environments.     

Noble metals in the bottom sediments of the Chukchi Sea

Abundance of noble metals (NM) and bulk chemical composition have been studied in bottom sediments of the Chukchi Sea. Distribution of NM and their correlation with major and trace elements in the sediments have been analyzed using multicomponent statistics. It was established that the average contents of NM in the bottom sediments of the Chukchi Sea significantly exceed those both in shelf terrigenous sediments and stratisphere. Osmium and iridium enrich mixed and pelitic sediments relative to shallow-water areas and their influx is presumably determined by erosion of coastal and bottom loose deposits. High Ag, Ru, Au, and Pt contents were identified in the clayey sediments enriched in biogenic elements in the individual areas of the Southern Chukchi plain (Chukchi sea) confined to the intersection zones of submeridional and sublatitudinal structures of the graben-rift system, which was formed in the Mesozoic and activated in the late Cenozoic time.