Types and physical properties of igneous rocks of Popov Island in Peter the Great Bay of the Sea of Japan

This paper presents the results of geological and petrophysical research carried out on Popov Island by the Pacific Oceanological Institute of the Far East Branch of the Russian academy of Sciences during 2003–2009. As a result, 7 types of rocks were identified. Their density and magnetic susceptibility have been determined. It was established that the rock types are clearly differentiated with respect to their physical parameters. The identified relationship allows one to use these physical properties, first of all, for the geological interpretation of the gravity and hydromagnetic survey carried out in the surrounding water area of Peter the Great Bay and, secondly, as an additional indicator for igneous rock typification on other islands of the region. Such comprehensive and integrated research was carried out for the first time in this area. The results obtained are important for solving the problem of the structural, compositional, and genetic relationships between the terrestrial and marine structures at the junction zone between the Japanese Basin and the adjacent continent.     

Fluxes of iron and manganese across the sediment–water interface under various redox conditions

Fluxes of dissolved forms of iron and manganese across the sediment–water interface were studied in situ in the Gulf of Finland and the Vistula Lagoon (Baltic Sea), and in the Golubaya Bay (Black Sea) from 2001 to 2005. Fluxes were measured using chamber incubations, and sediment cores were collected and sliced to assess the porewater and solid phase metal distribution at different depths. Measured and calculated benthic fluxes of manganese and iron were directed out of sediment for all sites and were found to vary between 70–4450 and 5–1000 µmole m^− 2 day^− 1 for manganese and iron, respectively. The behavior of the studied metals at various redox conditions in the near-bottom water and in the sediment was the main focus in this study. Our results show the importance of bottom water redox conditions for iron fluxes. We measured no fluxes at oxic conditions, intermediate fluxes at anoxic conditions (up to 200 μmole m^− 2 day^− 1) and high fluxes at suboxic conditions (up to 1000 μmole m^− 2 day^− 1). Total dissolved iron fluxes were generally dominated by iron(II). Contribution of iron(III) to the total iron flux did not exceed 20%. Obtained fluxes of manganese at all studied regions showed a linear correlation (r² = 0.97) to its concentration in the porewater of the top sediment layer (0–5 mm) and did not depend on dissolved oxygen concentrations of bottom water. Organically complexed iron and manganese were in most cases not involved in the benthic exchange processes.     

Magmatic Control of Gold Mineralization in Western Primorye

Geology of Ore Deposits - The article analyzes the regional gravitational field of northeastern China, Korea, and Western Primorye. The distribution of gold deposits is compared with the...