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Russian Geology and Geophysics

2015 year, number 5

1.
NEOPROTEROZOIC COLLISIONAL STYPE GRANITOIDS OF THE YENISEI RIDGE: PETROGEOCHEMICAL COMPOSITION AND UPb, ArAr, AND SmNd ISOTOPE DATA

A.D. Nozhkin1, N.V. Popov2, N.V. Dmitrieva1,3, A.A. Storozhenko4, N.F. Vasilev4
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
3Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
4Krasnoyarskgeols'emka Enterprise, ul. Berezina 3a, Krasnoyarsk, 660022, Russia
Keywords: Early Neoproterozoic, collisional granitoids, petrogeochemistry, geochronology, SmNd isotopy, Yenisei Ridge

Abstract >>
Collisional granitoid magmatism caused by the Early Neoproterozoic orogeny in the west of the Siberian craton is considered. New data on the petrogeochemical composition, UPb (SHRIMP II), ArAr, and SmNd isotopic ages of the Middle Tyrada granitoid massif in the northwestern Yenisei Ridge are presented. Plagiogranites, granodiorites, and quartz diorites of the massif are of calcareous and calc-alkalic composition. The elevated alumina contents and presence of accessory garnet permit them to be assigned to Stype granitoids. Their spidergrams show Rb, Ba, and Th enrichment, minimum Nb, P, and Ti contents, and no Sr depletion. The granitoids formed through the melting of plagioclase-enriched graywacke source, obviously Paleoproterozoic metaterrigenous rocks of the Garevka Formation and Teya Group (TNd(DM) = 2.02.5 Ga), judging from the isotope composition of the granitoids (TNd(DM2st) = 2200 Ma and εNd(T) = 6.0) and the presence of ancient zircon cores (1.801.85 Ga). Formation of granitoids took place in the final epoch of the Grenville collision events in the late Early Neoproterozoic (UPb zircon age is 857.0 9.5 Ma). In the Late Neoproterozoic, the granitoids underwent tectonothermal reworking caused by Vendian accretion and collision events on the southwestern margin of the Siberian craton, which explain the younger KAr biotite age, 615.5 6.3 Ma.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.001



2.
THE PHYSICOCHEMICAL DYNAMICS OF CARBONATIZATION OF THE ROCKS OF LITHOSPHERIC MANTLE BENEATH THE SIBERIAN PLATFORM

V.N. Sharapov1,2, K.V. Chudnenko3, A.A. Tomilenko1
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
3A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Carbonatization, lithospheric plate, metasomatism, model for a flow reactor

Abstract >>
Software modeling flow multireservoir systems was used to study the dynamics of carbonatization of lithospheric mantle with flows of magmatic fluids directed from a chamber in the upper mantle to the permeable zone, which dissects continental lithosphere. It has been shown that the region of physicochemical conditions of carbonatization in depleted mantle rocks corresponds to the narrow range of the compositions of hypothetical fluids. If the total content of the fluid is ~4 wt.% and the contents of SiO2 and Ca are 0.50.1 moles, (1) the ratio of the molar fractions of Si to Ca is less than unity; (2) the ratios of molar fractions in the CHO system are 1 : 2 : 3 or 2 : 1 : 2; (3) 8 < lg pO2 < 11; and (4) CO2 content in the fluid is higher than H2O content by a factor of 1.52, and chlorine significantly dominates over fluorine. If the content of the fluid phase is lower and this phase has a lower major-element content by an order of magnitude, the carbonatization becomes stronger as Ca content decreases.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.002



3.
PROGRADE TRANSFORMATIONS OF AMPHIBOLITES INTO ECLOGITES AND ECLOGITE-LIKE ROCKS IN THE LOW-PRESSURE FIELD OF THE ECLOGITE FACIES (by the example of the Belomorian Mobile Belt)

V.M. Kozlovskii1,2, L.Ya. Aranovich1, N.I. Frishman3
1Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017, Russia
2Lomonosov Moscow State University, Leninskie Gory, 119899, Moscow, Russia
3Saint Petersburg State University, Universitetskaya nab. 7/9, Saint Petersburg, 119034, Russia
Keywords: High-pressure metamorphism, thermobarometry, eclogites, amphibolites

Abstract >>
Plagioclase-bearing garnet-omphacite (GrtOmp) eclogites and garnet-augite (GrtAug) eclogite-like schists from the amphibolite and gneiss beds of the Belomorian Mobile Belt (BMB) have been studied. They are spread over a large area. In most of the studied objects, these rocks have preserved primary concordant relations with the host amphibolite and gneiss strata; they are not disturbed by late tectonic processes and are not genetically related to tectonic-melange zones. Their protoliths were amphibolite lenses in gneisses or large mafic zones composed of amphibolites. The GrtOmp eclogites formed in the low-pressure field of the eclogite facies (P = 12.513.0 kbar, T = 600630 ºC), and the eclogite-like GrtAug rocks, at the boundary between the amphibolite and eclogite facies (P = 9.611.1 kbar, T = 630700 ºC), under the intense impact of metamorphic fluid on the amphibolites. The compositional evolution of the rock-forming minerals during the formation of GrtOmp eclogites and eclogite-like GrtAug rocks followed the same scheme. The petrographic diversity of apoamphibolite rocks (GrtOmp eclogites and GrtAug schists) might be due to the difference both in the bulk composition of the metabasic protolith and in the ratios of CaO and Na2O activities in the metamorphic fluid. The relatively low content of CaO leads to the formation of GrtOmp paragenesis in eclogites. Higher CaO contents give rise to eclogite-like GrtAug rocks containing jadeite-poor clinopyroxene.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.003



4.
LUMINESCENCE IN DIAMONDS OF THE SAO LUIZ PLACER (Brazil)

V.P. Mironov1, A.L. Rakevich1, F.A. Stepanov1, A.S. Emelyanova1, D.A. Zedgenizov2, V.S. Shatsky2,3,4, H. Kagi5, E.F. Martynovich1,6
1Irkutsk Division of the Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 130a, Irkutsk, 664033, Russia
2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
3A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
4Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
5Geochemical Research Center (GRC), Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
6Irkutsk State University, ul. Karla Marksa 1, Irkutsk, 664003, Russia
Keywords: Diamond, defect, luminescence, laser, spectrum, microscopy

Abstract >>
Plates made of diamonds from the São Luiz province (Brazil) were investigated by confocal scanning luminescence microscopy. The samples have many macroinhomogeneities (cracks and inclusions), but there is a quasi-uniform distribution of luminescence centers in the bulk. At all investigated points of the crystals, the same group of centers was observed: N3, H4, 575, and a red band with a maximum at 690700 nm. The visible nonuniformities in the distribution of luminescence over the area of the plates are determined by relatively small fluctuations in the ratio of the intensities of individual bands in the spectra. Nitrogen centers of different degrees of aggregation (H4, N3, and 575 nm, with four, three, and one nitrogen atom, respectively) coexist in these crystals. In the same zones of the samples, the distribution of blue luminescence (N3 centers) is diffuse (uniform), but the distribution of yellow-green luminescence is characterized by layering on (111). This might be a consequence of the tangential growth of octahedron faces or a result of plastic deformation of the crystals and dislocations along (111).

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.004



5.
CALCAREOUS NANNOPLANKTON IN THE JURASSIC DEPOSITS OF THE DOBRUDJA FOREDEEP (Ukraine and Moldova)

L.M. Matlai
Institute of Geological Sciences, National Academy of Sciences of Ukraine, O. Honchara str. 55, Kyiv, 01601, Ukraine
Keywords: alcareous nannoplankton, Jurassic deposits, Dobrudja foredeep

Abstract >>
The paper is concerned with Jurassic calcareous nannoplankton from the Dobrudja foredeep. The regional Jurassic stratigraphy based on nannoplankton is considered. The NJ10/Stephanolithion speciosum, NJ11/Pseudoconus enigma, NJ14/Stephanolithion bigotii maximum, and NJ15/Cyclagelosphaera margerelii Zones, consistent with the International Nannoplankton Zonation Scheme, have been recognized in the deposits of the Dobrudja foredeep.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.005



6.
BIOGEOCHEMICAL SPECIFICS OF SAPROPEL FORMATION IN CISBAIKALIAN UNDRAINED LAKES (by the example of Lake Ochki)

G.A. Leonova1, V.A. Bobrov1, S.K. Krivonogov1,2, A.A. Bogush1,3, V.A. Bychinskii4, A.E. Maltsev1, G.N. Anoshin1,2
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
3Moscow State University, Leninskie Gory 1, Moscow, 119991, Russia
4A.P. Vinogradov Institute of Geochemistry, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Live material (plankton), biophile elements, biosedimentation, organic sediments (sapropel), chemical species of elements

Abstract >>
The biogeochemistry of organic lacustrine sediments (sapropels) has been poorly studied in Siberia. In this paper we show the specifics of sapropel formation caused by low pH and mineralization of water by the example of Lake Ochki in Cisbaikalia. The main sources of organic matter are zoo and phytoplankton, which concentrate mostly basic chemical elements and also some alkaline, alkali-earth, and chalcophile elements and more them to the sediment. The calculated enrichment factors (EF) have shown that the lake plankton is strongly enriched with phosphorus and chalcophile elements. The calculations have also revealed a great contribution of the plankton to the elemental composition of sapropel (Mebio, %): P (≈100), Cd (57), Hg (40), Se and Na (30), Zn (23), K (21), and Ca (15). Elements are rather uniformly distributed throughout the 3.2 m thick sapropel layer. Lithophile elements (Al, Sc, Ti, Y, Zr, Nb) and LREE are mostly from a terrigenous source. The high contents of mobile elements (Cd, Sb, Sn, Pb, Zn) in the upper part of sapropel are probably due to anthropogenic factors. The high Cu and Zn contents in some sapropel layers are probably related to the inflow of deep-level groundwaters, and the elevated contents of Hg, Cd, and Sb might have been caused by forest fires.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.006



7.
GRAVITY MONITORING AT OIL AND GAS FIELDS: DATA INVERSION AND ERRORS

A.N. Vasilevskiy1,2, Yu.A. Dashevsky2
1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Baker Hughes Incorporated, Novosibirsk Technology Center, ul. Kutateladze 4a, Novosibirsk, 630128, Russia
Keywords: , , , , Borehole geophysics, gravity surveillance, inversion, monitoring

Abstract >>
The present paper considers certain problems of gravity monitoring at oil and gas fields arising as a result of the inversion of repeat measurement data, when finding the positions of water-oil and water-gas contacts. The main sources of noise in gravity data are errors in vertical positioning of the tool, changes in atmospheric pressure, and variations in groundwater level and soil moisture. An algorithm based on using a multisensor borehole tool is proposed for a more accurate inversion. Examples of successful location of the water front while solving model problems with the help of this algorithm are provided.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.007



8.
THE BASIC PARAMETERS OF ACCELERATION SPECTRA FOR M ≥ 5 EARTHQUAKES IN THE BAIKAL RIFT ZONE

A.F. Drennov, V.I. Dzhurik, S.P. Serebrennikov, E.V. Bryzhak, N.N. Drennova
Institute of the Earths Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
Keywords: Acceleration spectra, characteristic angular frequencies of the spectrum, strong earthquakes, Baikal Rift Zone

Abstract >>
We consider the acceleration spectra of S waves from M = 56.5 earthquakes that occurred in three regions of the Baikal Rift Zone. The main characteristics of the shape and level of the spectra are given, and the difference between the spectra in the relative positions of the focus and seismic station is shown. Average acceleration spectra have been obtained for all three regions with regard to the form and magnitude of the earthquakes. The spectra have been transformed so that they correspond to the accelerations of M = 6.5 and M = 7.5 earthquakes. The conclusion is made that the spectra not necessarily retain their shape even with the same movements in the focus.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.008



9.
XRAY TOMOGRAPHY IN PETROPHYSICAL STUDIES OF CORE SAMPLES FROM OIL AND GAS FIELDS

S.V. Galkin1, A.A. Efimov1, S.N. Krivoshchekov1, Ya.V. Savitskii1, S.S. Cherepanov2
1Perm National Research Polytechnic University, Komsomolskii pr. 29, Perm, 614990, Russia
2LUKOIL PERM, ul. Lenina 62, Perm, 614990, Russia
Keywords: X-ray tomography, core samples, petrophysical studies, reservoir, porosity, inhomogeneity

Abstract >>
The porosity and permeability of core rocks were studied by X-ray tomography. This method has a high potential for studying petrophysical properties of rocks, because it permits not only a general quantitative estimation of the void volume but also visualization of the rock texture, including pores, cavities, cracks, and zones of different densities in the matrix. X-ray tomography permits detailed studies of rock inhomogeneity, which are necessary for the elaboration of reliable porosity-permeability models for hydrocarbon pools. The investigations at Perm State National Research Polytechnic University have shown that X-ray tomography of core samples has a wide spectrum of applications in petroleum geology. Nikon Metrology XT H 225 X-ray computed tomography makes it possible to examine samples with a standard diameter (30 mm) and whole core samples (100 mm). The structure of voids in carbonate and terrigenous rocks was studied on samples with standard and full diameters; the results of hydrochloric acid treatment of carbonate reservoir rocks were visualized; and the mechanical properties of rock salts were studied. Three-dimensional models for the structure of voids and mineral matrix of the core samples have been constructed with the use of the Avizo Fire software.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.009



10.
NONLINEAR WAVES AND SOLITONS IN MODELS OF FAULT BLOCK GEOLOGICAL MEDIA

V.G. Bykov
Kosygin Institute of Tectonics and Geophysics, Far East Branch of the Russian Academy of Sciences, 65, ul. Kim Yu Chen, Khabarovsk, 680000, Russia
Keywords: Nonlinear dynamics, sine-Gordon equation, soliton, stick-slip, strain wave, earthquake

Abstract >>
This is an overview of theoretical research on solitons and other nonlinear waves induced by deformation in fault block (fragmented) geological media, including a brief description of available models with their geophysical and geodynamic applications. The cited models correspond to the classical and perturbed sine-Gordon equations and use the rotation angle and displacement of fault blocks as dynamic variables. The models simulate kinematics and dynamics of traveling deformation fronts (kinks and solitons) generated in faulted rocks. The sine-Gordon equation is presented in its seismological and geomechanic applications for description of earthquake data and modeling of strain waves, faulting patterns, and subduction processes, including slow earthquakes and periodic episodic tremor and slow slip (ETS) effects.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.04.010