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Russian Geology and Geophysics

2018 year, number 8

1.
EARLY DEVONIAN VOLCANICS OF SOUTHEASTERN GORNY ALTAI: GEOCHEMISTRY, ISOTOPE (Sr, Nd, and O) COMPOSITION, AND PETROGENESIS (Aksai complex)

V.I. Krupchatnikov1, V.V. Vrublevskii2, N.N. Kruk3,4
1Gorno-Altaiskaya Ekspeditsiya, ul. Sovetskaya 15, Maloeniseiskoe, 659370, Altai Territory, Russia
2National Research Tomsk State University, pr. Lenina 36, Tomsk, 634050, Russia
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
4Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Early Devonian magmatism, magnesian andesitoids, Nb-enriched basaltic andesites, A-type granitoids, geochemistry, Gorny Altai, Central Asian Orogenic Belt

Abstract >>
Geological, geochemical, and isotope (Sr, Nd, and O) parameters of Early Devonian (405 Ma) volcanics of southeastern Gorny Altai (Aksai and Kalguty volcanotectonic structures) are discussed. The studied igneous rock association comprises magnesian andesitoids, Nb-enriched basaltic andesites, and A-type peraluminous silicic rocks (dacites, rhyolites, granites, and leucogranites). Magnesian andesitoids (mg# > 50) are characterized by a predominance of Na among alkalies (K2O/Na2O ≈ 0.1-0.7), medium contents of TiO2 (~0.8-1.3 wt.%) and Al2O3 (~12-15 wt.%), enrichment in Cr (up to 216 ppm), and low Sr/Y ratios (4-15). The Nb-enriched (Nb = 10-17 ppm) basaltic andesites have high contents of TiO2 (1.7-2.7 wt.%) and P2O5 (0.4-1.4 wt.). The A-type granitoids are characterized by high contents of K (K2O/Na2O ≤ 60) and alumina (ASI ≤ 2.9) and depletion in Ba, Sr, P, and Ti. The magnesian andesitoids and Nb-enriched basaltic andesites are products of melts generated in the metasomatized lithospheric mantle; silicic magmas formed through the melting of Cambrian-Ordovician metaturbidites of the Gorny Altai Group and, partly, Early-Middle Cambrian island-arc metabasites. The above rock association might have resulted from a plume impact on the lithospheric substrates of the continental paleo-margin during the evolution of the Altai-Sayan rift system.



2.
GEOCHEMISTRY OF RARE-EARTH ELEMENTS IN THERMAL WATERS OF THE UZON-GEYZERNAYA HYDROTHERMAL SYSTEM (Kamchatka)

G.A. Karpov1, P.A. Schroeder2, A.G. Nikolaeva1
1Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences, Piipa bulv. 9, Petropavlovsk-Kamchatsky, 683006, Russia
2University of Georgia, Department of Geology, Athens, GA 30602-2501, USA
Keywords: Uzon Caldera, rare-earth elements, thermal waters, thermal fields, hydrothermal clays

Abstract >>
Precisional analyses of the abundances of La, Ce, and major elements in thermal waters and rocks of the Uzon-Geyzernaya volcanotectonic depression, supplemented by published data on a number of modern high-temperature hydrothermal systems of Kamchatka and two other areas of the world, allowed defining genetically important patterns of rare-earth elements (REE) distribution. The La and Ce abundances positively correlate with silica contents both in fresh igneous rocks of the study areas and in the products formed by hydrothermal processes. All studied hydrothermal clays are enriched in La and Ce. The general enrichment trend is similar to the pattern of positive correlation between the La and Ce abundances. Geothermal waters display a strong relationship between REE enrichment and pH. Enhanced REE enrichment trend is observed in thermal waters with abundant SO42- and K. The REE versus Cl and B diagrams show two individual fields reflecting the level of acidity-alkalinity of thermal waters. These data demonstrate that La and Ce concentrations in the products of modern hydrothermal systems (in fluids and secondary mineral phases) are governed by wallrock composition, anionic water composition, and pH/Eh-dependent adsorption processes.



3.
PLATINUM-GROUP MINERAL ASSEMBLAGE OF THE PRIZHIMNY CREEK (Koryak Highland)

A.V. Kutyrev1, E.G. Sidorov1, A.V. Antonov2, V.M. Chubarov1
1Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences, bulv. Piipa 9, Petropavlovsk-Kamchatskii, 683006, Russia
2A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
Keywords: Platinum-group minerals, placer deposits, Pt-Fe alloys, Ural-Alaskan-type massifs, Koryak-Kamchatka belt

Abstract >>
In the alluvial deposits of the Prizhlimny Creek (southern part of the Koryak Highland), grains of platinum-group minerals are found along with gold. We have established that the grains are native platinum (Pt, Fe) containing Cu (up to 5 wt.%), Os (up to 8 wt.%), and Rh (up to 2 wt.%). Inclusions in the platinum are native osmium (the content of Ir impurity reaches 12 wt.%, the average content being 0.2-4 wt.%), an unnamed intermetallic compound of composition PtRh, sulfides and arsenides of PGE (cooperite, laurite, malanite, cuproiridsite, cuprorhodsite, sperrylite, hollingworthite, unnamed compounds PdS, (Ir,Ru)S2, (Ir,Pt)S2), Cu, and Fe (bornite, chalcopyrite), chromite, and Cr-magnetite. Replacement of native-osmium crystals by compound IrO2 is described. It has been established that this compound formed during oxidation accompanied by the replacement of isoferroplatinum by native platinum. The data obtained agree with the results of study of platinum-group mineral assemblages from placers localized in weakly eroded Ural-Alaskan-type massifs whose apical parts formed under high oxygen activity conditions. Clinopyroxenites of the Prizhimny massif are considered to be the potential source of PGE.



4.
THE SOURCE OF SULFUR IN SULFIDE DEPOSITS IN THE SIBERIAN PLATFORM TRAPS (from isotope data)

V.V. Ryabov1, O.N. Simonov2, S.G. Snisar2, A.A. Borovikov1
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Polar Division of Public Joint Stock Company Mining and Metallurgical Company Norilsk Nickel, Gvardeiskaya pl. 2, Norilsk, Krasnoyarsk Territory, 663330, Russia
Keywords: Sulfur, sulfate reduction, sulfur isotope composition, sulfide deposits, anhydrite, Norilsk district

Abstract >>
The source of sulfur in giant Norilsk-type sulfide deposits is discussed. A review of the state of the problem and a critical analysis of existing hypotheses are made. The distribution of δ34S in sulfides of ore occurrences and small and large deposits and in normal sedimentary, metamorphogenic, and hypogene sulfates is considered. A large number of new δ34S data for sulfides and sulfates in various deposits, volcanic and terrigenous rocks, coals, graphites, and metasomatites are presented. The main attention is focused on the objects of the Norilsk and Kureika ore districts. The δ34S value varies from -14 to +22.5 in sulfides of rocks and ores and from 15.3 to 33 in anhydrites. In sulfide-sulfate intergrowths and assemblages, δ34S is within 4.2-14.6 in sulfides and within 15.3-21.3 in anhydrites. The most isotopically heavy sulfur was found in pyrrhotite veins in basalts (δ34S = 21.6), in sulfate veins cutting dolomites (δ34S = 33), and in subsidence caldera sulfates in basalts (δ34S = 23.2-25.2). Sulfide ores of the Tsentralnaya Shilki intrusion have a heavy sulfur isotope composition (δ34S = 17.7 ( n = 15)). Thermobarogeochemical studies of anhydrites have revealed inclusions of different types with homogenization temperatures ranging from 685ºC to 80ºC. Metamorphogenic and hypogene anhydrites are associated with a carbonaceous substance, and hypogene anhydrites have inclusions of chloride-containing salt melts. We assume that sulfur in the trap sulfide deposits was introduced with sulfates of sedimentary rocks (δ34S = 22-24). No assimilation of sulfates by basaltic melt took place. The sedimentary anhydrites were steamed by hydrocarbons, which led to sulfate reduction and δ34S fractionation. As a result, isotopically light sulfur accumulated in sulfides and hydrogen sulfide, isotopically heavy sulfur was removed by aqueous calcium sulfate solution, and residual metamorphogenic anhydrite acquired a lighter sulfur isotope composition as compared with the sedimentary one. The wide variations in δ34S in sulfides and sulfates are due to changes in the physicochemical parameters of the ore-forming system (first of all, temperature and P CH4) during the sulfate reduction. The regional hydrocarbon resources were sufficient for large-scale ore formation.



5.
U-Pb SHRIMP-II ages of titanite and timing constraints on apatite-nepheline mineralization in the Khibiny and Lovozero alkaline massifs (Kola Peninsula)

N.V. Rodionov1, E.N. Lepekhina1, A.V. Antonov1, I.N. Kapitonov1, Yu.S. Balashova1, B.V. Belyatsky1, A.A. Arzamastsev2,3, S.A. Sergeev1,3
1A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
2Institute of Earth Sciences, St. Petersburg State University, Srednii pr. 31, St. Petersburg, 199004, Russia
3Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, Makarova nab 2., St. Petersburg, 199034, Russia
Keywords: U-Pb dating, SHRIMP, titanite, sphene, agpaitic syenites, Khibiny, Lovozero, apatite-nepheline ores

Abstract >>
Results of this study of titanite samples collected from silicate rocks and apatite-nepheline-(sphene) ores from Paleozoic polyphase alkaline nepheline syenite complexes of the Khibiny and Lovozero massifs revealed the possibility of their in-situ U-Pb dating using sensitive high-resolution ion microprobe SHRIMP-II with an accuracy of 1.0-1.5%, which is comparable with that of U-Pb zircon analysis. Employing different approaches to age determination of the formation of the U-Pb system of titanites, the combined isochrons and mixing lines were plotted from the data obtained from the differentiated complex samples (121 analyses of five Khibiny samples and 52 analyses of one Lovozero sample) and apatite-nepheline ores (120 analyses of five Khibiny samples and 88 analyses of three Lovozero samples). They indicate synchronous crystallization of titanite in silicate rocks throughout the complexes: 374.1 3.7 Ma for the Khibiny massif and 380.9 4.5 Ma for the Lovozero massif, and attest to the later formation of phosphate-rare-metal ores: 371.0 4.2 and 361.4 3.2 Ma, respectively. The relatively delayed ore mineralization specific to the Lovozero massif can be accounted for the significantly lower volumes of magmatic melt and ore fluid involved, different thermal conditions, and the pattern of the investigated mineralization. As such, the obtained U-Pb data from titanite make it possible to limit significantly the time interval (most likely, not exceeding 15-20 Ma) comprising the evolution and activity of the ore-magmatic system of major agpaitic complexes, which is probably associated with plume magmatism.



6.
HYDROCARBONS OCCLUDED BY ASPHALTENES

V.A. Kashirtsev1,2,3
1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Institute of Oil and Gas Problems, Siberian Branch of the Russian Academy of Sciences, ul. Oktyabrskaya 1, Yakutsk, 677891, Russia
3Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Bitumen, hydrocarbons, asphaltenes, occlusion

Abstract >>
Homologous series of alkenes and dimethylalkanes mostly with the odd or even number of carbon atoms in the molecule have been identified in chloroform extracts from the organic matter of the Upper Paleozoic deposits of the Vilyui syneclise, penetrated by the superdeep well SV-27 at depths below 5 km. It is assumed that these unusual hydrocarbons resulted from the destruction of asphaltene occlusions under severe P-T conditions at great depths and that the hydrocarbon generation began in the zone of postdiagenetic transformations of sediments. This hypothesis was tested in the sections of deposits whose organic matter underwent catagenesis of different grades. On the basis of these results, zones of emergence, transition, and destruction of occlusions have been recognized.



7.
ORE-BEARING FLUIDS OF THE ELDORADO GOLD DEPOSIT (Yenisei Ridge, Russia)

N.A. Gibsher1, A.A. Tomilenko1, A.M. Sazonov1, T.A. Bulbak1, M.O. Khomenko1, M.A. Ryabukha1, E.O. Shaparenko1, S.A. Silyanov2, N.A. Nekrasova2
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Institute of Mining, Geology, and Geotechnology, Siberian Federal University, pr. Svobody 79, Krasnoyarsk, 660041, Russia
Keywords: Quartz, gold, ore-forming fluid, hydrocarbons, δ34S, 3He/4He, Ar-Ar age

Abstract >>
The Eldorado low-sulfide gold-quartz deposit, with gold reserves of more than 60 tons, is located in the damage zone of the Ishimba Fault in the Yenisei Ridge and is hosted by Riphean epidote-amphibolite metamorphic rocks (Sukhoi Pit Group). Orebodies occur in four roughly parallel heavily fractured zones where rocks were subject to metamorphism under stress and heat impacts. They consist of sulfide-bearing schists with veins of gray or milky-white quartz varieties. Gray quartz predominating in gold-bearing orebodies contains graphite and amorphous carbon identified by Raman spectroscopy; the contents of gold and amorphous carbon are in positive correlation. As inferred from thermobarometry, gas chromatography, gas chromatography-mass spectrometry, and Raman spectroscopy of fluid inclusions in sulfides, carbonates, and gray and white quartz, gold mineralization formed under the effect of reduced H2O-CO2-HC fluids with temperatures of 180 to 490 C, salinity of 9 to 22 wt.% NaCl eq, and pressures of 0.1 to 2.3 kbar. Judging by the presence of 11% mantle helium (3He) in fluid inclusions from quartz and the sulfur isotope composition (7.1-17.4 δ34S) of sulfides, ore-bearing fluids ascended from a mantle source along shear zones, where they «boiled. While the fluids were ascending, the metalliferous S- and N-bearing hydrocarbon (HC) compounds they carried broke down to produce crystalline sulfides, gold, and disseminated graphite and amorphous carbon (the latter imparts the gray color to quartz). Barren veins of milky-white quartz formed from oxidized mainly aqueous fluids with a salinity of <15 wt.% NaCl eq at 150-350 ºC. Chloride brines (>30 wt.% NaCl eq) at 150-260 ºC impregnated the gold-bearing quartz veins and produced the lower strata of the hydrothermal-granitoid section. The gold mineralization (795-710 Ma) was roughly coeval to local high-temperature stress metamorphism (836-745 Ma) and intrusion of the Kalama multiphase complex (880-752 Ma).



8.
NOBLE METALS IN BLACK SHALES OF THE SUKHOI LOG GOLD DEPOSIT (East Siberia): EVIDENCE FROM SCINTILLATION ARC ATOMIC-EMISSION SPECTROMETRY

I.E. Vasileva1, E.V. Shabanova1, E.M. Goryacheva2, O.T. Sotskaya2, V.A. Labusov3,4,5, O.A. Nekludov4, A.A. Dzyuba3,4
1Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
2N.A. Shilo Northeastern Integrated Research Institute, Far East Branch of the Russian Academy of Sciences, ul. Portovaya 16, Magadan, 685000, Russia
3Institute of Automatics and Electrometry, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 1, Novosibirsk, 630090, Russia
4OOO VMK-Optoelectronics, pr. Akademika Koptyuga 1, office 100, Novosibirsk, POB 376, 630090, Russia
5Novosibirsk State Technological University, pr. K. Marksa 20/1, Novosibirsk, 630073, Russia
Keywords: Noble metals, certified reference materials of black shales, scintillation arc atomic-emission spectrometry

Abstract >>
Scintillation arc atomic-emission spectrometry (SAES) is used to study noble metals (NM), including Au, Ag, Pt, Pd, Ir, Os, Rh, and Ru, in black shales of the Sukhoi Log gold deposit (Irkutsk Region, Russia), with a focus on total NM contents in samples and on the compositions and sizes of NM-bearing particles. The estimated sizes of gold particles and their distribution are confirmed by results of scanning electron microscopy combined with energy dispersive X -ray microanalysis (SEM-EDX). The SAES results are in satisfactory agreement with earlier SEM-EDX data on NM species but reveal a much greater number and diversity of element associations.



9.
FEATURES OF MAGMATISM-RELATED METALLOGENY OF GORNY ALTAI AND RUDNY ALTAI (Russia)

I.V. Gaskov1,2
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Metallogeny, mineral deposits, mineralization, magmatism, Gorny Altai, Rudny Altai

Abstract >>
The Rudny Altai and Gorny Altai regions had different geologic histories and differ in metallogenic patterns. The Vendian-Early Cambrian to Permian-Triassic multistage evolution of Gorny Altai included subduction, accretion-collision, and rifting events accompanied by magmatism and related mineralization. Metallogeny evolved in discrete pulses, with especially abundant Late Paleozoic-earliest Mesozoic mineralization. The Devonian-Carboniferous pulse produced diverse mineral deposits (iron, mercury, gold, silver, molybdenum, tungsten, cobalt, complex ores, and rare earths), some of considerable economic value. The territory of Gorny Altai includes several large ore districts that belong to different zones. They are the Beloretsk-Kholzun iron district in the west, the Kayancha-Sinyukha fluorine-gold district in the northeast, the Kurai gold-mercury and Yustyd rare-metal-silver districts in the southeast, and the Kalguty rare-metal-tungsten and Ulandryk U-REE-Cu districts in the south. The largest mineral deposits are Kholzun (Fe, P2O5), Karakul (Co, Bi), Sinyukha (Au), Aktash and Chagan-Uzun (Hg), Ozernoe and Pogranichnoe (Ag), Kalguty (Mo, W), Alakha (Li, Ta), Rudnyi Log (Y,Fe-specularite), and Urzarsai (W-scheelite). Mineralization in Rudny Altai is mainly pyritic: copper-pyrite, pyrite-complex ore, and barite-complex ore. It resides in suprasubduction basalts and rhyolites and in Emsian to Frasnian island-arc volcanics at different stratigraphic levels of Devonian volcanosedimentary sequences in six ore districts. The Kurchum high-grade metamorphic block hosts copper-pyrite and gold-quartz mineralization related to Late Paleozoic-Early Mesozoic volcanism.



10.
PROCESSES OF FORMATION OF FLUORITE-LEUCOPHANE-MELINOPHANE- EUDIDYMITE ORES OF THE ERMAKOVKA F-Be DEPOSIT (western Transbaikalia)

L.B. Damdinova1, B.B. Damdinov1, N.V. Bryanskii2
1Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakhyanovoi 6a, Ulan Ude, 670047, Russia
2A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Beryllium, hydrothermal ore formation, metal content of solutions, fluid inclusions, Na-Be silicates, pH, LA-ICP-MS

Abstract >>
Fluorite-leucophane-melinophane-eudidymite ores of zone XVIII of the Ermakovka F-Be deposit were studied by geological, mineralogical, and thermobarogeochemical methods. Contents of Be and impurity elements (Li, Na, Mg, Al, Si, Cl, K, Mn, Fe, Cu, Zn, Nb, Mo, Ag, Sn, W, and Pb) in fluid inclusions in fluorite of this zone have been first determined by LA-ICP-MS. It is shown that fluorite-leucophane-melinophane-eudidymite ores were formed by alkaline high-F low-salt (6.0-12.5 wt. % NaCl equiv.) solutions with a relatively low content of Be (0.0002-1.04 g/kg of solution). Fluorite and beryllium minerals were deposited in ores in a wide range of P-T conditions. The early fluorite-phenakite paragenesis formed at high temperatures (480-650 ºC) and high pressures (>3 kbar). At the late low-temperature stage, phenakite was replaced by Na-Be silicates (eudidymite and melinophane-leucophane) at < 220 ºC and < 770 bars. The Be-ore deposition was due to the destruction of a predominant beryllium fluoride-carbonate complex as a result of the crystallization of fluorite during the metasomatic replacement of limestones. Eudidymite and melinophane-leucophane formed at low temperatures under high activity of Na and Ca and low activity of Be and F in highly alkaline solutions.



11.
THERMAL FIELD AND GEOTHERMAL MODELS OF THE LITHOSPHERE IN THE CONTINENT-OCEAN TRANSITION ZONE OF NORTHEASTERN EURASIA

P.Yu. Gornov, G.Z. Gilmanova
Yu.A. Kosygin Institute of Tectonics and Geophysics, Far Eastern Branch of the Russian Academy of Sciences, ul. Kim Yu Chena 65, Khabarovsk, 680000, Russia
Keywords: Heat flow, temperature, Moho discontinuity, lithosphere

Abstract >>
The region under study is located in the active «transition zone from the Eurasian continent to the Pacific Ocean. The zone occupies not only the continent-ocean border area (continental coastline, marginal seas, island arcs, and deep-sea trenches) but also the margins of intracontinental regions of the Eurasian continent with different structures and regimes of development. The transition zone is a natural buffering and damping regulator of the interaction between the Eurasian and Pacific plates and is characterized by intense orogenesis, contemporary volcanism, active seismicity, diverse geothermal regime, and highly nonuniform measured heat-flow values. Available geothermal data for the region are not sufficiently generalized. After the latest maps compiled in the 1990s, new data have been obtained and new geoinformation technologies have been developed. In the study presented in this paper, available geothermal information has been generalized and a detailed heat flow distribution map has been compiled and used to calculate Moho temperatures, to determine the thickness of the geothermal lithosphere, and to construct distribution maps of these parameters.



12.
FIRST RESULTS OF GPS MESUREMENTS ON ULAANBAATAR GEODYNAMIC TEST GROUND

A.I. Miroshnichenko1, N.A. Radziminovich1, A.V. Lukhnev1, F.L. Zuev1, S. Demberel2, D. Erdenezul2, M. Ulziibat2
1Institute of the Earths Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
2Institute of Astronomy and Geophysics, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
Keywords: GPS measurements, crust strain, fault, seismicity, Mongolia

Abstract >>
First results of the analysis of GPS measurement data obtained from 18 sites of two local geodynamic test grounds in the vicinity of Ulaanbaatar (Mongolia) for the period 2010-2015 have been presented. Horizontal velocity vectors are coordinated with each other in the ITRF2014 system and with the velocities from the IGS permanent station ULAB. The sites are shifted in the E-SE direction at a rate of 25-30 mm/yr, with the displacement azimuth averaging 105. With respect to Eurasia, the vectors for most of the sites are to a certain extent S-trending, but their continued motion (2-4 mm/yr) is also oriented SE with the azimuth range 130-150. Relative horizontal velocities tend to decrease toward the southeast, with their zonal structures established within the Ulaanbaatar test ground area. The western part of the Ulaanbaatar test ground is dominated by roughly W-E extension, the elongation is ε1 = (12-16)‧10-8 yr-1. The shortening NW-SE trending strain with calculated value ε2 = 22.4‧10-8 yr-1 characterizes the test grounds eastern part. The highest values of the maximum shear strains (εmax = (10-14)‧10-8 yr-1) form an extended area in the center of the test ground, elongated in the northeastern direction, conformably with the strike of the major geologic structures. The strain distribution pattern of the Emeelt test ground located within the eponymous seismogenic structures is characterized by the crustal elongation (5‧10-6 yr-1) trending SE-NW and less pronounced shortening in the SW-SE directions. The axial part of the fault crossing the test ground in the NW direction exhibits maximum deformations.