by Academician Yuri LEONOV, member of the National Steering Committee on participation of the Russian Federation in preparation and implementation of measures within the framework of the International Polar Year

The Regular International Polar Year, which lasted from March of 2007 through February of 2009, proved fruitful: in the course of a two-year cycle of system observations in the Arctic and Antarctic regions scientists of different countries obtained a lot of new data on our planet. Academician Yuri Leonov, head of the geological and geophysical studies carried out during this period told about some results achieved by Russian specialists to our correspondent Yevgeniya Sidorova.

— Mr. Leonov, how was research work conducted under the auspices of the International Polar Year organized in our country?

—  The Russian Government established the National Steering Committee on participation of the Russian Federation in preparation and implementation of measures within the framework of the International Polar Year (its co-chairmen were Alexander Bedritsky, Head of the Federal Service for Hydrometeorology and Arthur Chilingarov, Deputy Chairman of the State Duma). The Steering Committee and its subordinate Interdepartmental Coordinating Research Committee (chairman—Ivan Frolov, Director of the Arctic and Antarctic Research Institute) were entrusted with coordination of studies carried out under projects of the international program and national projects. All of them were grouped into seven directions. Under only one direction, which was called "Geological History and Lithosphere of Polar Regions" and included geological and geophysical studies (the direction was headed by me), a total of 30 projects were realized, including 4 projects in the Antarctic region and the rest in the Arctic region. The Russian Academy of Sciences and the Federal Agency for Nature Management of the Ministry of Natural Resources of the Russian Federation were initiators and executing agencies. Some projects were carried out by working groups, consisting of spesialists from defferent institutions, sometimes with the participation of foreign specialists.

—  Were all studies of 2007-2008 subordinated to the plans of the International Polar Year?

—  Not quite so. A major part of them was conducted indeed "under the banner" of the International Polar Year. However, a great number of works were carried out, so to say, in a usual mode. Their results are equally interesting both in scientific and applied aspects. I shall not touch them in our discussion, though we must remember that the International Polar Year is essentially not more than an

Diagram of geophysical research in the Commonwealth Sea: profiles of seismic, magnetometric and gravimetric observations and points of bottom seismic stations (red dots) (H. Leichenkov).

important stage in long-term studies of the polar regions. Its tasks and programs did not arise suddenly with a wave of a magic wand of the Snow Queen, and they do not terminate after expiry of the time limit of studies.

—  Still, it would be interesting to know the main results of studies at that period.

—  I prefer the word "some" results, as the "main" results are much more than can be mentioned in our interview, though it is not always easy to separate the main from the minor. Each of 30 projects gave new information, which is processed now by specialists. Here we can dwell only on a number of issues. At the same time, I would like to remind you that the problems under discussion will not exhaust a whole spectrum of the completed studies. Besides, my information on the activities in the Polar Year reflects the results obtained by different working groups, which I shall refer to later on.

—  When you said "under the banner of the Polar Year", I involuntarily imagined ships sailing to an open ocean. Were the naval expeditions actually the main source of information on geology and geophysics of the ocean ?

—  This is really so. The expeditions had taken place, though their organization took maximum efforts of the academic institutes as to get funds for marine operations they almost always had "to scrape the bottom of the barrel", as the Russian tale about a small round loaf has it.

The most significant studies were carried out in the course of an expedition of the All-Russia Research Institute of Geology and Mineral Resources of the World Ocean (VNIIOkeangeologia) and the Polar Marine Prospecting Expedition with the participation of the Wegener Institute (Germany) (headed by Herman Leichenkov and Valery Masolov from VNIIOkeangeo-logia) on two research vessels, namely, Russian Alexander Karpinsky and German Polarstern. The exploration area covered an extensive zone in the southern part of the Indian Ocean, in the Commonwealth Sea, and in the southern part of Kerguelen volcanic plateau. Due to a wide choice of remote geophysical methods, a section of the Earth's crust was obtained for the first time for this region from the upper horizons of the mantle to the sedimentary cover, and a chart of the structure and a model of geological history of the region were suggested on the basis of actual materials.

According to the new model, the contemporary oceanic crust of the Commonwealth Sea formed as a result of the split of the ancient continental lithosphere approximately 134 mln years ago, i.e. at the beginning of the Cretaceous, simultaneously or somewhat earlier (with a difference of not more than the first millions of years) with disintegration and separation of the continents of India and Australia. This fact is testified by two symmetric sequences of magnetic anomalies revealed in this sea, whose centers are axes of the dead spreading paleoridges. It should be remembered that according to modern scientific ideas the process of separation of continents and formation of a new oceanic crust is marked just by such structures. According to the above-mentioned authors, a mantle plume (a flow of the deep heated substance rising up to the surface from the Earth's mantle) arose at that time, whose further development led to the formation of a volcanic province in the southern part of the Kerguelen plateau (120-110 mln years ago).

Information on the structure of the sedimentary cover in the basin of the Commonwealth Sea, located in the transition area from the continental lithosphere of the Antarctic region to the oceanic bed of the Indian Ocean has both sci-

Model of a deep structure of the Earth's crust of the continental outskirts of Antarctic regions and the southern part of the Kerguelen plateau, compiled according to the data of deep seismic sounding with the use of bottom stations (H. Leichenkov; simplified version).

entific and applied meaning. The obtained material is important for analyzing the history and mechanisms of processes in the ocean/continent transition area, and, in practical terms, it is a base for assessment of the sedimentary basin potential from the point of view of hydrocarbon raw materials. This problem takes on a new meaning in recent years due to an apparent forthcoming division of the Antarctic shelf and continental slope into economic zones of a number of states.

As to the Arctic region, I should like to mention a series of expeditions undertaken by the RAS Geological Institute in cooperation with the Norwegian Oil Directorate and with the participation of researchers of the RAS Vernadsky Institute of Geochemistry and Analytical Chemistry on the national research vessel Academician N. Strakhov. The comprehensive studies were carried out under several projects of the International Polar Year headed by Yuri Leonov, Andrei Zayonchek, Alexander Mazarovich and Mikhail Khutorskoy, the last three Drs. Sc. (Geol. & Min.) from the Geological Institute. The work area was located in the northern part of the Barents Sea shelf, where detailed studies were conducted at three test ranges, i.e. in waters to the south-west of Franz Josef Land Archipelago, to the east of Severo-Vostochnaya Zemlya island of Spitsbergen Archipelago ("Storoya gutter"), in the triangle between Spitsbergen Archipelago, Medvezhy island and the Knippovich Range wings ("the mouth" of Medvezhinsky gutter).

—  As the Barents Sea shelf is a large oil-and-gas province, probably it is studied in greater detail at present, is that so ?

—  Indeed, a number of organizations carry out systematic and full-scale studies of the deep-seated structure of this sea. Moreover, they try to get detailed information on the sedimentary cover, which is an object of search for oil and gas fields. We cannot compete with them, but we have our own definite "niche" for studies.

Our interests are in the sphere of badly studied problems of geology and geodynamics of the transition area from continent to ocean with emphasis on processes of the present time. These processes are manifested to the full in the structure and composition of the upper horizons of the sedimentary cover, sea-bottom relief (bathymetry), peculiarities of magmatism in general and volcanism in particular, and the character of geothermal regime (heat flow). That is why we chose this region for studies. The shelf s outer zone is essentially a continental edge, a boundary of the continental slope and the oceanic bed, which accordingly has an oceanic crust.

Of prime importance is the fact that studies of these elements supplemented the concurrent research and substantiation of available geological data on the island's ground (Spitsbergen or Svalbard and Franz Josef Land islands) and also on the ocean and the continental slope (the Knipo-vich Range in the North Atlantic region and the Svalbard continental slope). A special expedition was carried out there prior to the International Polar Year. All this will allow to elaborate and has already partially elaborated the existing models and ideas of interconnection of processes on the continent and in the ocean.

Now I shall give a detailed account on two or three important issues. First of all, we have received up-to-date data on geothermics, which amplify the previous assessments of background values of the heat flow of the Barents Sea plate. As it has turned out, they make 50-70 mW/m . But the extreme values up to 520 mW/m² in the Storoya gutter differ enormously from the latter and testify to its contemporary tectonic activity. Bathymetry and the tectonic structure of this interesting meridional gutter,

expressed in the bottom relief of the shelf's outer zone and in the upper part of the continental slope, have also been studied, and an underwater volcano was presumably found here, its study is planned at a later time. The new data alongside with other features of regional geology and the presence of similar but perhaps today less active gutters (Franz-Victoria, St. Anna, Voronina) east of the system allow to elaborate a model of the up-to-date contemporary geodynamics of the northern part of the Barents Sea shelf (Svalbard plate), within the limits of which destruction (rift genesis) processes of the continental crust manifest themselves.

Perhaps, one should in a similar manner interpret the data obtained at the RAS Institute of Geochemistry (by RAS Corresponding Member Alexander Sobolev and others) as a result of studies of a stony material, taken by dredging from the ocean in the axial zone and on the wings of the Knippovich Range (in the oceanic crust), and Neogene-

Diagram of tectonics and earthquakes (with a magnitude from 3.0 to 7.0) of the Laptev Sea shelf and the north of the Verkhoyansk Range (L. Imaeva); (1-6)--grabens(hollows, limited by ruptures), bold-face lines-active shifts, dots and circles-epicenters of earthquakes.

Marine expeditions of the research vessel ACADEMICIAN N. STRAKHOV (voyages 24, 25, 26) in 2006-2009 in the north-western part of the Barents Sea shelf and the Knipovich Range.

Quaternary volcanic rocks of the north-western Spitsbergen (in the continental crust). Eventually the location of the latter abreast of magmatic bodies of the North Atlantic region was clearly demonstrated. Attention is drawn both by dynamics of magmatic processes on Spitsbergen and the data on the heat flow, which probably reflects changes taking place now in the continental crust of the shelf edge area. It is established according to subtle features of the composition of some minerals (for example, olivine) that magmatic rocks of the Quaternary age as compared to the more ancient Neogene rocks are near to oceanic bodies, which are characteristic of the wings and axial zone of the Knipovich Range. In other words, the geochemical characteristics of these rocks disclose an ever-increasing in time effect of oceanic processes on the continental crust, which breaks down or is subjected to destruction.

—  You gave a detailed description of the achievements of marine expeditions. But in what areas of the Arctic and Antarctic regions did the Russian scientists carry out ground research and what goals did they set?

—  Geological and geophysical studies were carried out in several areas of the Arctic region. Almost all of them are based on field observations. They represent a large range of works different in tasks and methods; therefore it is difficult to describe them, let alone their details. But it should be pointed out that, apart from handling regional problems, they almost always provide invaluable material for conclusions and creation of generalizing models, which is extremely important. We have no sufficient data on direct observations in the Arctic basin, and they are supplemented rather slowly. Constructions made on the basis of the interpretation of geophysical fields are not always simple. Therefore, observations on the continent and islands have a special role ensuring control over the models related to the internal parts of the Arctic basin. Here are some examples.

The described situation is typical of the eastern part of the Arctic basin, i.e. the Canadian Hollow. Practically all diagrams of its geological structure lack cogency. This explains a priority attitude attached to the studies conducted by the RAS Geological Institute in the region of New Siberian Islands, on Stolbovoy and Belkovsky islands (Alexander Kuzmichev, Dr. Sc. (Geol. & Min.)), and on the Wrangel Island (Sergei Sokolov, Dr. Sc. (Geol. & Min.)). They are connected with paleotectonic reconstructions of the cretaceous South Anyui ocean and, in combination with earlier data on the continental land, contribute to better understanding of interrelation between the tectonic elements of the North American and Eurasian plates and geological history of the Canadian Hollow.

Another debatable problem concerns an extension on the continent of the spreading Hakkel Ridge, which is an axial range of the so-called Eurasian basin of Western Arctic regions. It is the only oceanic structure established here with confidence, which allows drawing an analogy with other oceans of the Earth. It approaches the continent in the region of the Laptev Sea, and here a question arises: What is then happening with it, is it disappearing or continuing in the continental crust? Answer to this question depends in many ways on understanding of the structure and geodynamics of the transition area. Therefore, a special project headed by Lyud-mila Imaeva, Cand. Sc. (Geol. & Min.) from the Institute of the Earth Crust of the RAS Siberian Branch, was devoted to this problem. As a result of studies of the active fault zones and calculation of parameters of earthquake focal mechanisms, a refined reconstruction of the field of tectonic stresses was suggested as well as a preliminary model of contemporary geodynamics of the North Verkhoyansk region (north of the Verkhoyansk Range) and the Laptev Sea.

Owing to works carried out by an international team of scientists headed by Alexander Tebenkov, Cand. Sc. (Geol. & Min.) from the Polar Marine Prospecting Company, a refined diagram of correlation of Caledonian structures of the western—Atlantic sector of Arctic regions, including

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Tectonic zoning of the White Sea region (A. Baluev). Red lines denote Sinian grabens.

Spitsbergen, Medvezhy Island, Eastern Greenland and Scandinavia, appeared on the Spitsbergen Archipelago. According to the existing concepts, fragments of the Caledonian folded belt are present in the above-mentioned regions (it formed in the Silurian-Devonian periods of geological history of the Earth), which were disengaged during formation of the Atlantic Ocean at a later time. The data on their correlation are used in the reconstruction of the formation history of the North Atlantic region.

Problems of different nature, related to tectonics and a deep structure of lithosphere of the continent and the shelf, were tackled in the region of the White Sea and the southern part of the Barents Sea. For this territory a new tectonic map was prepared with emphasis on rift structures of the Sinian and Paleozoic age, which form a structural frame of the crust and are of interest in terms of assessment of hydrocarbon potential of the region. The work was carried out by a team of researchers from several organizations of the Russian Academy of Sciences and the Ministry of Natural Resources (Alexander Baluev from the Geological Institute et al.).

—  Geological works on the continent and islands were conducted in many areas of Russian Arctic regions. There were probably generalizing studies at that period, which covered Arctic regions as a whole or its large parts.

—  In this context, of special importance is compilation of panarctic (or circumarctic) stratigraphie diagrams or, in other words, diagrams of partition, correlation and identification of age sequence (time of formation) of rock complexes for the whole area of Arctic regions. They are mainly biostratigraphic, but when possible they are supplemented with data on radiometric dating. With such material available, we can determine correlation of sediments and events in different regions and then create paleotectonic and paleogeographical reconstructions for separate geological epochs, models of development and structure of sedimentary basins of the continent (which is important for oil-and-gas geology), the shelf and the continental slope. Besides, interpolation and extrapolation of data obtained by the aforesaid way provides to some extent monitoring of reality of models of the geological structure and development suggested for deep-sea parts of the Arctic basin.

Creation of similar diagrams as well as stratigraphie studies in general is a labor-intensive and long process. Another stage (if not final, then making it possible to dot many "i's") of studies for spans of Late Triassic, Jurassic and Early Cretaceous periods was carried out during the International Polar Year. Apart from the research team of the Geological Institute (project manager Viktor Zakharov, Dr. Sc. (Geol. & Min.)), members of several academic

Reconstruction of the Arctic basin in the Triassic, Jurassic and Late Cretaceous according to paleobiogeographical data (V. Zakharov).

institutions. Rosnedra agency, Lomonosov Moscow State University, and a number of other state universities took part in the project.

The area of field studies covered polar territories of Eurasia from Spitsbergen to New Siberian Islands Archipelago. The main results of the expeditions was a collection of material with a high degree of detailed observations not reached by their predecessors. Based on its analysis and with account of data obtained in previous years, a detailed circumarctic correlation diagram of Jurassic sediments was compiled, which can serve as a basis for geological mapping and mineral exploration. Created and presented in the form of maps were new reconstructions of the paleogeographical, hydrological and climatic situations in the territory of Arctic regions.

It should be added to the aforesaid that at the same time a marked progress was achieved in coordination of benchmark elements of arctic (boreal) and southern (thetic) stratigraphie diagrams. The most remarkable result lies in the fact that it was for the first time in more than a century that due to the efforts of specialists from different countries of Western Europe and North America, a direct boreal-thetic correlation was realized in respect of boundary between Jurassic and Cretaceous layers of Arctic regions and Western Europe.

It is necessary to explain that the term "thetic" originates from the name of the southern paleocean Tethys, whose contemporary relicts are Mediterranean, Black and Caspian seas. We face here a set of problems, which are not simple and insufficiently elaborated but at the same time extremely important. The problem is that boreal and thetic stratigraphie diagrams are based on essentially different groups of fossils existing in different latitudes. But the solution of arising problems predetermines accuracy of comparison (correlation) of geological developments in Arctic regions with the events in middle and low latitudes, which is necessary for an inclusion of Arctic regions into geological models and reconstructions of a global scale, either paleogeographical, paleoclimatic or any other constructions.

—  Studies of climatic and paleoclimatic changes are one of the main aspects of the International Polar Year. Were any projects devoted to this problem included into geological and geophysical programs ?

—  Yes, studies of transformation of climate and the environment in the geological past occupied a significant place in our work. Modern science strives to answer the following question: is it necessary to consider the present processes as natural fluctuations or they are a consequence of anthropogenic emissions of some substances, mainly CO₂, into the atmosphere? A short period of instrumental observations proper does not provide any answer, though historical materials, data of precision analysis of core samples obtained from glaciers and lake sediments, and assessment of volumes of anthropogenic emissions confirm a decisive role of natural fluctuations (and disavow in a greater measure the correctness of basic provisions of the Kyoto Protocol of 1997). Digressions into the geological past provide additional reasoning, which allows to reconstruct not only short-term (high-frequency) fluctuations but also long-term trends of climatic changes and sometimes help understand their causes and mechanisms of their impact on biosphere, including on man in the early periods of his existence. Hence the interest to paleoclimatic studies, in our case as applied to the Arctic territory.

Within the framework of one of the projects Alexei German, Dr. Sc. (Geol. & Min.), (Geological Institute) carried out research of the climate of the Cretaceous using fossil flora from the sediments of the Albian and Turanian tiers on the Kotelny and Novaya Sibir islands in the New

Settling of early inhabitants of Arctic and Subarctic regions (A. Velichko). Main stopping places: 1-Mesolithic period and New Stone Age (10,000-4,000 years ago); Late Palaeolithic period: 2-15,000-12,000 years ago; 3-23,000-16,000 years ago; 4-24,000-35,000 years ago. Probable routes: 5-Eastern Europe, 6-Eastern Siberia, 7-North-East of Asia- Beringiya-North America, 8-North of Canada-Greenland.

Siberian Islands Archipelago. This flora was discovered by Russian polar expeditions headed by Eduard von Toll in 1886 and 1900-1901.* In different years the collections of ancient plants were replenished, and now the whole material together with new collections has become a basis for reconstruction of paleoclimatic parameters according to the nature of leaves using the CLAMP (Climate-Leaf Analysis Multivariate Program) method worked out by the American scientist Jack Wolfe. As it turned out, in the middle of the Cretaceous a damp moderately warm climate prevailed in Arctic regions, which was characterized by warm summer temperatures and mild winters, which attracted heat-loving plants and big dinosaurs to settle there!

Studies of climate and paleogeographical reconstructions of the Quaternary also produced new interesting results. The long-term international project "The initial settlement of Arctic regions by man in conditions of the changing natural environment" (headed by Andrei Velichko, Dr. Se. (Geogr.), RAS Institute of Geography) involved institutes of the Russian Academy of Sciences, Russian Academy of Medical Sciences, scientific organizations and universities of Norway, Great Britain, USA and Denmark. The final stage of the project fell on the period of the International Polar Year. Research carried out in the north of Eurasia and North America showed a good correlation of impulses in the settlement of these regions by people and recession (departure from conquered positions) with climatic epochs. It became possible to reconstruct living conditions of our forefathers and migration paths of ancient inhabitants of North Eurasia, from the first "reconnaissance" attempts of man to penetrate into the Mousterian epoch (beginning of the Late Pleistocene) to the end of the settlement process of Arctic and Subarctic regions in the second half of the Holocene.

—  When will results of these and other interesting studies be published? After all, it is time to sum up the International Polar Year.

—  Main publications are still ahead. The following materials of meetings have already been published, such as the 2-volume "Geology of Polar Regions of the Earth" (2009), the joint monograph "Road to the North: the Environment and the Earliest Inhabitants of Arctic and Subarctic Regions" (2008). Some papers were published in the Novosti MPG (International Polar Year News) journal.

A series of works on the results of the Polar Year 2007/2008 in seven volumes will be published very soon, and one volume will be devoted to geology and geophysics.

* See: V. Glushkov, "Sannikov Land:  Fact or Fiction?", Science in Russia. No. 2, 2004.-Ed.

Structure of the Earth's crust and upper parts of the mantle in the shelf area and the Lomonosov Range (V. Poselov; simplified version): AB-surface of acoustic foundation; K₁--roof of the upper crust (crystalline foundation); K₂--surface of the lower crust; M-surface of the mantle.

New cartographic material, the result of two major international projects, is also expected presently. First, it is the Atlas of Geological Maps of Circumpolar Arctic Regions, which includes geological (scale 1:5 mln), gravimetric and magnetic anomaly maps, and is compiled under guidance of Oleg Petrov, Director of the All-Russia Research Geological Institute named after A. Karpinsky. Secondly, it is the Tectonic Map of Antarctic Regions (compiled under guidance of Garik Grikurov and Herman Leichenkov, both Cands. Se. (Geol. & M in.) from the VNIIOkeangeologia).

—  In conclusion I would like to ask one more question. Against the background of the activity connected with the International Polar Year 2007/08, was anything done to substantiate boundaries of economic zones of Russia in Arctic regions?

—  It is well-known that in recent years, due to abruptly rising interest to the geopolitical impact and mineral resources of the region, including the internal parts of the Arctic basin (the Arctic Ocean), the problem of delimitation of economic zones of the northern (and not only) countries has become acutely evident. It directly concerns Russia and sometimes is referred to as the "problem of the external limit of the continental shelf.

These issues have been considered within the framework of a special project of VNIIOkeangeologia headed by Viktor Poselov, Dr. Se. (Geol. & Min.). As a result of the analysis and generalization of practically the whole available material of seismic profiles, interpretation of the bathymetrie map and maps of magnetic anomaly and force of gravity fields, with involvement of materials on the geology of East Arctic shelf and islands, a model of the Earth's crust structure has been developed, and reconstruction of the geological history of the region of Central Arctic Rise* has been worked out. It has been demonstrated that according to the data available today, the Earth's crust of major elements of this region, and first of all the Lomonosov Range and the Mendeleev Rise, is close to the crust of continental type.

—  Could you please explain, what are the features these various types of the Earth's crust differ by?

—  The Earth's crust consists of several layers of different composition and, consequently, of diverse density, therefore seismic waves pass through them with different velocity. For continents and oceans it differs by a set of the said layers, their depth and total thickness. These features are revealed during measurements of geophysical fields, mainly, force of gravity field and velocities of seismic waves.

Thus, these features in combination with other considerations testify, according to the project managers, to the fact, that the Lomonosov Range and the territory of the Arctic shelf of Russia in the comparatively recent geological past represented a single ensemble of continental structures with a common history of development. Its separation to shelf and more deep-water parts took place at a relatively recent time (20-10 mln years ago or even later) as a result of a moderate amplitude of sinking of the central part of the Arctic basin. Such sinking could be accompanied by the crust's transformation, but apparently without a loss of the main "continental" characteristics. Such scenario of events, which contemplates a close connection between the said elements and structures of the Eurasian continent, calls for further working out of details, including a more extensive analysis of comparative material related to other regions of the World Ocean, and appropriate works will be undoubtedly continued. However, even the obtained arguments allow to consider the said scenario the most probable, and this is surely a favorable conclusion for our country.

* See: Yu. Leonov, "Studies of Arctic Regions Go On", Science in Russia, No. 3, 2008.--Ed.