The Permian–Triassic komatiite–basalt complex in the Song Da rift, northwestern Vietnam, occurs in the axial part of this structure and includes komatiites, komatiitic basalts, olivine basalts, and subvolcanic bodies of dunite and plagioclase-bearin g wehrlite hosting Ni–Cu–PGE sulfide ores. Volcanic rocks contain olivine- and pyroxene-spinifex textures. The Ban Phuc deposit consists of two major orebodies. The first one is of vein type, zonal, with average Ni/Cu of 2.5 and Ni/Co of 33. In the centra l part, it is composed of massive chalcopyrite – pentlandite – (violarite) – pyrrhotite ores with associated sulfarsenides of Ni and Co , heazlewoodite, tsumoite, parkerite, sperrylite, and michenerite. Marginal parts of (pentlandite) – pyrrhotite – chalcopyrite, a nd violarite – chalcopyrite composition contain nickeline, maucherite, sperrylite, and michenerite. The second orebody is composed of disseminated ores with an average Ni content of 1.2%. The plots of mantle-normalized contents of noble metals, Ni and Cu reflect their non-fractionated distribution, typical of komatiites. Ore formation proceeded in two stages: 1) magmatic stage, including sulfide–silicate immiscibility and fractional crystallization of the sulfide melt, and 2) postmagmatic hydrothermal processes. The saturation of the komatiitic melt with respect to a sulfide at an early stage of formation of the Ban Phuc suite is suggested by a steeper trend of olivine composition on the Ni in olivine – Fo diagram compared with olivine from ore-free volcanic rocks of the komatiite–basalt series. Later on, fractional crystallization of a fluid-bearing sulfide melt was the mos t important factor in the formation of ore. Enrichment of Cu-bearing ores from zonal orebodies in Pd and Au corresponds to their concentration in the residual sulfide melt during fractionation of Mss. The unusual Pt concentrations of the Fe–Ni ores are due to the presence of sperrylite, which contains between 0.9 and 3.4 wt.% Sb at the high-temperature stage (900–1000 °C) of the volatile-saturated sulfide. At the lower-temperature stage, sulfarsenides of Ni, Co, and Fe appeared, together with michenerite at 500–400°C. At 300°C and below, tsumoite and the Cu–Pb–Ag–Bi sulfosalts made their appearance.
The paper presents the result of analyses of the Azov Sea fishery resources state for the last 15 years of the last century up to the present time. The information on quantitative and qualitative composition of commercial catches is obtained from the data of fishery statistics. Changes in temperature and salinity and their anomalies relative to mean annual values are highlighted. The first four commercial species with maximum catches have been identified: anchovy, kilka, gobies and Redlip mullet. The dynamics of their ratio, at different periods of the current century, may indicate the influence of external conditions (temperature, salinity, etc.). The forecast on increase of catches of the listed species and recommendation on development of the Azov sea fishery development programme, including all directions of fishery, introduction of the newest achievements of science and technology in development of aquaculture and other branches connected with rational use of aquatic biological resources of the sea are given.
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