The International Body for Benthic Studies, an intergovernmental organization under the UNO, approved the prospecting plan for deepwater poly-metallic sulphides for Russia so as to search and extract this mineral wealth in July 2011. According to national specialists, our country can become a leader in the exploration of these mineral resources of the Atlantic Ocean.

Deepwater polymetallic sulphides are copper, nickel and zinc ores localized mainly at 1-5 km depths in the water areas of the Pacific and Atlantic oceans. According to prognoses, ores in the area allocated for our country contain 2.5-10 percent of copper on average, including admixtures of gold. That is why geological surveying in the international area of the ocean bottom should stimulate in perspective a balanced development of the national mineral resources base.

The Russian area of the bottom is being explored by the Polar Marine Geological and Prospecting Expedition (St. Petersburg and Lomonosov). Since 1993, within the borders of the Mid-Atlantic Ridge, this organization in association with the All-Russia Research and Development Institute of Geology and Mineral Resources of the World Ocean (St. Petersburg) has discovered three large hydrothermal sulphide fields named in honor of outstanding geologists--Alexander Ashadze, Yuri Semenyov (Polar Marine Geological and Prospecting Expedition) and Alexander Logachyov from the Leningrad Mining Institute (today St. Petersburg State Mining University), as well as three hydrothermal ore fields-Krasnov (in honor of Sergei Krasnov, famous researcher of deepwater polymetallic sulphides from the All-Russia Research and Development Institute of Geology and Mineral resources of the World Ocean), Zenit-Viktoriya and Peter-burgskoye. All works--a series of geological and geophysical operations--are carried out on board the Professor Logachyov ship.

In particular, multibeam echosounding makes it possible to estimate general geomorphological structure of the area under exploration. Another technology--side survey profile hydrolocation--allows to obtain a sonographic (ultrasonic) image of the bottom to understand how sedimentary and magmatic rocks are formed there and identify tectonic structures the ores could be connected with. Frequent abnormalities of the natural electric field constantly measured by scientists support the hypothesis that the ores should be very close.

Scientists take samples of bottom waters and make conclusions on the occurrence of ore objects depending on deviations from normal temperature, salinity, turbidity and chemical content of water. There is another diagnostic technology--chemical and mineralogical analysis of bottom samples enabling to reveal differences* of hydro-thermal nature in the rocks. Television profiling makes it possible to assess the general form, sizes and location of

* Differences in this context mean a totality of mineral objects, differing by morphological properties from others of the same species.--Ed.

Science in Russia, No.2, 2012

discovered deposits, to carry out monitoring of the state of bottom surface and local biota.

A new hydrothermal field called Irinovskoye field (in honor of four women--members of the expedition, who have the same name Irina and who are directly involved in the description of ores) was discovered in the summer of 2011 during the 34th voyage of the Professor Logachyov ship in the area of 13°20' N. It is located in the north-eastern part of the underwater mountain in the western side of the rift valley.

This mountain has a complex geological structure; according to expert opinion, it is a place where serpentinized ultramafic rocks* reach the sea bottom through a smooth crust fracture. The aforementioned Logachyov, Ashadze and Semyonov fields also pertain to the similar structures. In the course of a regular voyage to Irinovskoye field, scientists took samples of hydro-thermally-modified basalts and dolerites** with vein sulphide mineralization. It is a place where two ore fields were outlined, and to the north-west a site was fixed, promising for discovery of deepwater polymetal-lic sulphides.

Ore deposits were studied within the framework of the 17th project of the RAS Presidium "Mineralogy and Geochemistry of Sulphide Deposits of Mesozoic and Contemporary Oceans (Comparative Analysis)" at the expense of grant MK-485.2011.5 "Evolution of Hydro-thermal Systems of Pyrite and Gold Ore Fields in Mafite-Ultramafite Complexes of Southern Ural, Western Tuva and Central Atlantic Regions" issued to young candidates of sciences by the RF President. Collected data were described and systematized by Irina Melekestseva, Cand. Sc. (Geology and Mineralogy), senior research assistant of the Mineralogy and Ore Genesis Laboratory, RAS UB Institute of Mineralogy (Miass).

Textural studies of samples taken at different areas of Irinovskoye field were carried out by means of ore-facial*

* Ultramafic rocks-a general term used to identify groups of magmatic feldspar-free rocks of a normal petrochemical series; serpentine--magnesium-ferrous hydrosilicates.--Ed.

** Dolerites--crystal-clear fine - and medium-grained basalts with a peculiar intergranular structure.--Ed.

'Facial analysis--a set of methods and special means used to determine physico-geographical conditions of the past epochs by certain difierences.--Ed.

analysis; then, the obtained results were compared with the released data for similar deposits of the World Ocean, which enabled scientists to speak about the existence of a well-developed hydrothermal system located in the area of 13°20' N., currently inactive, as it contains a number of formations. For example, relatively new pipes of "black" and "white" smokers* and massive copper and copper-zinc-pyrite ores typical of central parts of sulphide hills are located close to oxidized intergrown pipes of "black smokers" (a sign of the fading process). There were found massive sulphuric-pyrite ores deposited on the sides of sulphide hills; sulphide breccias testifying to the processes of destruction of ore bodies; vein sulphide mineralization in the hydrothermally-changed volcanic rocks, representing the stockwork** part of the system; hydrothermal opal bodies pointing to the low-temperature activity at the sides of hydrothermal fields; rinds of iron hydroxides with manganese minerals and atacamite formed as a result of submarine oxidation of sulphide ores.

The main practical tasks of subsequent cameral studies of ores will include a detailed textural-structural and mineralogical analyses by means of microscopes, detection of minerals-concentrators of precious metals, as well as evaluation of sulphide raw materials at a level of elements-admixtures, which is essential, for example, for practical use of sulphuric pyrite.

It is absolutely clear that scientific work on board the research ship is more comfortable than in the taiga. But specialists disclosing deepwater secrets of the Atlantic Ocean are very enthusiastic about the opportunity to understand processes of formation of pyrite deposits on the continents, find unknown "chain loops".

National scientists have enough time to carry out research works and make decisions, but they have to keep to a schedule: an area of the sea bottom assigned to our country consists of 100 blocks, approximately 10x10 km each; half of them must be explored in 8 years, other 25 blocks--in 2 subsequent years. By that time scientists should find most promising and economically efficient sulphide fields.

I. Melekestseva, "Sulphide Deposits in the Ocean: Their Future is Near", Science of Ural newspaper, No. 24, 2011

'Smokers--subwater formations around run-outs of thermal waters from the ocean floor. Black smokers are usually met along the boarders of tectonic plates where ore-bearing hot fluids reach the surface. White smokers are built of calcareous rocks.--Ed.

"Stockworks belong to a group of hydrothermal formations occurring in the course of depositing of a metal-bearing substance from hot mineralized solutions circulating in cracking rocks.--Ed.