by Nikita BOGDANOV, RAS Corresponding Member, RAS Institute of the Lithosphere of Border and Inland Seas, director

The continental shelf occupies a third of the Russian Federation's area and almost all of its sea economic zone. Over half of the whole volume of sedimentary rock of Eurasia's north is buried here. The mineral wealth hidden in these deposits is immense; this is true above all of hydrocarbons.

The sea shelf, or a shallow-water offshore zone, has the earth's crust structure similar to that of the continental land. The shelf zone is relatively narrow and does not exceed 200 km across in the Atlantic, Indian and Pacific Oceans. However, it is as much as 2,500 km wide in areas where North America approaches Eurasia, namely in most of the Bering Sea and in all of the Chuckchee Sea. The shelf width shrinks abruptly westward.

The study of sea shallow waters and the use of their resources began long before the systematic exploration of deep-water regions. The world's first project of oil extraction on the shelf was in the Caspian (the Neftyanye Kamni, or "Oil Rocks", deposit off the Apsheron Peninsula) and then in the Mississippi's estuary, with oil mined on the bottom of the Gulf of Mexico; and next came similar ventures off the shores of Malaysia and Indonesia. As, late in the 1960s, came the turn of the North Sea (its central part), where the extraction of oil and natural gas was launched, the depth of exploratory and commercial drilling was as much as 200 - 300 m.

Today close to 30 percent of hydrocarbons is being mined in marine regions. Among the first water areas like that were the Cook Bay in the Bering Sea and the Okhinsky district in Sakhalin's north (Okhotsk Sea) ^* . Later on, North America's largest deposit was discovered off Alaska's coast (at Prudo Bay); also, significant deposits of oil and gas-condensate were found off Novaya Zemlya (Stockmann deposit), near the Pai-Hoi Peninsula and on the Kolguyev Island (Barents Sea) as well as in the south of the Pechora and Kara Seas.

The ratings of other regions are very high-all the more so as actually any water areas can be explored today. For example, off the Brazilian coast, on South America's continental slope, oil is extracted from strata under 2 km-deep waters.

The turning point in sea-floor mining occurred in 1968, when the first research drilling vessel, Glomar Challenger, was launched. At first the sea-

^* See: S. Golubchikov, "Arctic Shelf-Russia's Major Reserve", Science in Russia, No. 1, 2000. -Ed

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drilling program was exclusively American; but then, in 1973, the Soviet Union joined up as its first foreign participant. Subsequently seven other countries joined in, with about fifty taking part now. Yet Russia is out: in 1992, for lack of funds, our explorers could no longer afford to take part, though we own the world's largest shelf expanses.

By now over 1,700 wells have been sunk in keeping with this international program- both in deep-water and in shallow-water areas, mostly at temperate and equatorial latitudes. Separate research parties have been in the northern Atlantic, and off the shores of Greenland and Antarctica. Only four wells have been drilled in our water areas-near Kamchatka and the Commodore (Commanders') Islands.

Throughout the 20th century Russian scientists were carrying out intensive explorations in Eurasia's polar part and on islands of the Arctic Ocean and then, with the start of marine geophysical and geological studies, also within the water areas of this country's economic zone. The data thus amassed proved to be priceless, even though kept in the custody of various departments.

The Europrobe Project adopted more than a decade ago provided for the mapping of Russia's arctic shelf, specifically, with respect to geological-geophysical profiles all across the latitudinal trend of the European craton (consolidated massif) as far as the Urals and beyond. Western experts made a thorough study of materials on their respective regions. However, what concerned our territories, first and foremost, the Timan-Pechora and some other areas, our Western colleagues made it appear as if those were blank spots not explored at all. But this quarreled with the actual truth, and we had to prove it in deed. So experts from many research centers pooled efforts - from Tyumen, Ukhta, Murmansk, St. Petersburg and other cities- under the aegis of the RAS Institute of the Lithosphere of Border and Inland Seas. This research project got support from the RF Ministry of Industry, Science and Technologies, the RF Ministry of Power Engineering, the Russian Foundation for Basic Research, and the Presidium of the Russian Academy of Sciences within the framework of the World Ocean Program. All the available data were thus brought together and evaluated; besides, tectonic maps of our water areas and adjacent lands were drawn up, which is of the utmost importance in more ways than one-like reaffirming the priority of Russian science, better knowledge of the structure of Russia's shelves and their assessment as the potential sources of mineral wealth, hydrocarbons in the first place. ^*

The first map to be drawn up was that of the Barents Sea floor. Although the drilling works in the Barents Sea were limited in scope, there is good room for well- substantiated extrapolations since its water area has many islands that have been studied quite well. Much farth-

^* See: I. Gramberg et al., "Continental Shelf: Russia's Last Fuel-and-Power Reserve", Science in Russia, No. 1, 1998. -Ed.

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er eastward, the Okhotsk Sea has been explored well enough geologically, the only sea where we are mining oil.

While studying Arctic regions, we had to find out how far hydrocarbon-rich horizons extend under the sea floor and what type structures are of common occurrence there. For instance, in Eurasia's Arctic shallow waters, the structural pattern is determined by the orientation of folded belts both on the continent and on the islands and archipelagos, with some oriented nearly at the right angle with the coastal line. According to geophysical data, they are limited by in-depth fault benches of sublati- tudinal extension. It appears that the shelf of the Barents, Kara and Laptev Seas remained part of the continent even after the collapse of Pangaea, a supercontinent that united all the continents and that broke up about 230 miHion years ago.

The situation is somewhat different for the East Siberian, Chuckchee, Bering and Okhotsk Seas. The earth's crust there is composed of terrains (microplates, geoblocks) of different age. Colliding, they moved to the continent east of the Siberian craton at different times, from the Permian down to the Cretaceous (300 - 150 mm years ago).

Here, in this popular science article, we cannot go all too deep into the geological structure, tectonics and dynamics of the territories and water areas mapped. Rather, we find it more important to stress the urgency and prospects of related studies.

We cannot tell what could have happened to the economy of Western Europe, Britain and Norway in particular, had not oil and gas deposits been discovered in the North Sea. The situation of Russia would have been lackluster, too, in the absence of the hydrocarbon resources of Western Siberia and of the Far North. But these resources are not infinite, their explored reserves are shrinking, so that our country might face a shortage of hydrocarbon crudes already in the near future. Elsewhere in the world, the situation is far from inspiring optimism. That is why the Russian Arctic is now in the focus of attention on the part of many geological organizations of the European Union and the United States.

Certainly, the Arctic shelf is a treasure-trove of minerals yet to be opened up. Over the last millions of years the Arctic Ocean has been developing rather as an inland sea. Huge expanses there were under land even not so long ago, geologically.

This is seen in the numerous remains of mammoths and lemmings found on sea islands. Unlike polar bears, those animals never walked on ice.

The sea shelf is a part of a continent that has sunk below sea level. Small wonder that about the same useful minerals can be found there as on dry land. Our Arctic shallow waters cover colossal deposits of sedimentary rock-more than is available all over Russia! These deposits must be rich in oil and gas. The problem is how to detect, explore and use these riches.

The author of the present article has repeatedly raised the question of prospecting or at least of geophysical surveying in the Ilpinsky trough between the Kragintsev Island and the mainland. A well was sunk there more than 15 years ago, and it confirmed the presence of thick sedimentary deposits. There were all signs for the presence of oil and gas-bearing structures, or "traps". Had geologists found oil over there, the Koryak region, Kamchatka and Chukotka would have gotten fuel in the end.

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We are quite certain about that. There are oil (hard bitumen) shows on dry land in the locality-not altogether uninhabited either, for it has a small community. Yet one is in no hurry to realize an economically advantageous project, though only around $2,000,000 is needed to start it.

We could cite quite a few examples like that. True, the eastern part of the northern shelf is not development-friendly. There are as good as no population centers along the coast. And yet the American continent next to this region has the Trans-Alaska oil pipeline in commission. What with the declining oil output in the giant Prudo Bay deposit, it would be a good bargain for us to get the Americans interested in the development of our deposits.

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Exploratory prospecting in the Russia-owned western part of the Arctic shelf could be launched in the immediate future. Extending from the coast northwards is the East- Barents trough having an immense sedimentary cover, over 15 km deep. In this zone, west of Novaya Zemlya, a huge deposit, the Stockmann (or Stockmannskoe, not Stockmanovskoe! - as one will call it now and then) deposit was discovered not so long ago.

Likewise worthy of attention is another major tectonic structure, the Kola-Kanin monocline north of the White Sea. Thick strata containing organic substances started accumulating there before the Venda period, or 900 to 700 mm years ago. ^* For example, in North Africa productive oil- and gas-bearing strata occur in deposits like that. The Venda period, the heyday of unicellular plankton and multicellular invertebrates, was favorable to oil accumulation. There were also several dramatic changes in climatic conditions causing mass extinctions of animals. Thus a vast amount of organic matter came to be sedimented, with all this mass drifted to the north, toward the Kola-Kanin monocline. This area holds good prospects for hydrocarbon prospecting, also considering its rather convenient location. It would be fine if two or three wells were drilled on the Kanin Peninsula-which is a technically feasible and not so much costly undertaking. But the results would pay off the expenses.

Unfortunately oil- and gasmen would rather mine in long-discovered deposits with little thought given to future prospects-what's going to happen in 5 or 10 years, let alone in a more distant future. An odd situation obtains: nearly all major world companies and organizations are maintaining contacts with RAS research centers (interested as they are in our oil and gas mining)-all but our home companies!

I do believe that geological and geophysical explorations on our territories and water areas should be carried out by ourselves and, still better, if on our own money. We would thus be able to keep controlling the use of our natural wealth. In some instances, though, participation of other countries is absolutely necessary. For example, we made the Caspian maps in cooperation with scientists of all states of the region and-let me stress it again!-with no involvement of profit-making structures that show but little desire to shell out for research projects. Yet, as it was noted way back in the 19th century: nothing is more practical than a good theory. This truth fully applies to geology, for our science is at once both theoretical (map-making, general descriptions) and practical, because it is involved not only with the study of the earth, but also with the discovery and exploitation of mineral riches.

Arctic prospecting is a very expensive job, and so far we cannot afford dozens of like projects a year. But we can send at least one large expedition to the Arctic seas, and another -to the Okhotsk and Bering Seas for basic geological studies. We should expand explorations in the Caspian and in the Black-and-Azov Seas region, too. In this way we shall solidify the base for specific prospecting targets.

Today the very first tectonic and bathymetric maps of Russia's coastal seas have been created, in Russian and in English. They are supplemented with monographic descriptions of the structure and geodynamics of corresponding regions. But only the first step in the right direction has been made. We should push ahead with the work begun, or else Russia will risk forfeiting the balance of work done by major research and production collectives and, in the long run, sacrifice the guarantee of our country's future, the wealth of our sea shelf.

^* See: D. Rundkvist, N. Yushkin, "Treasures of Timan and Urals", Science in Russia, No. 4, 2002. -Ed.

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