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Russian Geology and Geophysics

2014 year, number 8

1.
CONDITIONS OF BASALT FORMATION IN THE DZHIDA ZONE OF THE PALEOASIAN OCEAN

V.A. Simonov1,2, I.V. Gordienko3, S.I. Stupakov1, A.Ya. Medvedev4, A.V. Kotlyarov1, S.V. Kovyazin1
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akad. Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
3Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakhyanovoi 6a, Ulan-Ude, 670047, Russia
4Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
Keywords: Basaltic complexes, clinopyroxenes, Dzhida zone, Paleoasian Ocean

Abstract >>
Petrological and geochemical studies performed with invoking data on the compositions of clinopyroxenes have clarified the conditions of formation of Vendian-Cambrian basaltic complexes in the Dzhida zone of the Paleoasian Ocean (northern Mongolia and southwestern Transbaikalia). The research was based on a comparative analysis with reference igneous basaltic associations. Of special importance are our microprobe data on trace and rare-earth elements in clinopyroxenes from igneous rocks of different present-day geodynamic settings, namely, N-MORB (Mid-Atlantic Ridge, Central Atlantic), OIB (Bouvet Island, South Atlantic), WPB (within-plate tholeiitic plateau basalts of the Siberian Platform), and boninites of ensimatic arcs (Izu-Bonin island arc, Pacific). The studies have shown that the paleo-oceanic structures in the district of the Urgol guyot formed during geodynamic processes under the impact of mantle plumes on oceanic spreading crust, which resulted in oceanic basaltic plateaus and within-plate oceanic islands. All these structures were later superposed by typical island-arc structure-lithologic associations. Formation of basalt complexes in the Dzhidot guyot district proceeded with a stronger effect of enriched plume melts of within-plate oceanic islands as compared with the Urgol guyot. This is evidenced from petrochemical and geochemical data showing the development of OIB-type magmatic systems on the oceanic basement. Data on clinopyroxenes confirm the participation of mantle plume in this process, which led to the evolution of magmas from typical oceanic basalts (MORB) to plateau basalts and OIB.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.001



2.
AN EXPERIMENTAL STUDY OF HYDROXO COMPLEX FORMATION IN BASIC AND NEAR–NEUTRAL SOLUTIONS OF RARE-EARTH ELEMENTS AND YTTRIUM AT 25 oC

S.A. Stepanchikova, R.P. Biteikina, G.P. Shironosova, G.R. Kolonin
V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Rare-earth elements, hydrolysis, complex formation, tetrad effect

Abstract >>
We have studied the hydrolytic behavior of Y3+ and trivalent ions of rare earth elements in aqueous solutions at 25 oC. The stepwise stability constants of hydroxide complexes were measured by spectrophotometry, using m -cresol purple and 1-(2-pyridylazo)-2-naphthol as pH indicators at an ionic strength no more than 0.0005. The results showed that at pH ranging between 6.0 and 11.0 in freshly prepared solutions of REE trichlorides, lanthanides are presented as Ln 3+, Ln(OH)2+, Ln(OH)2+, and Ln(OH)30. The plots of the formation constants of monohydroxo complexes of 4 fn ions M3+ versus atomic number Z deviate from smooth ones and consist of four convex curves. This phenomenon is also observed in normalized spectra of REE concentrations in natural objects and is known as the tetrad effect. The obtained data give an insight into the relationship between REE complex formation and REE fractionation in geochemical processes and can be used for physicochemical modeling of geochemical systems.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.002



3.
MINERAL INCLUSIONS IN Fe-Pt SOLID SOLUTION FROM THE ALLUVIAL ORE OCCURRENCES OF THE ANABAR BASIN (northeastern Siberian Platform)

E.V. Airiyants1, S.M. Zhmodik1,2, P.O. Ivanov3, D.K. Belyanin1,2, L.V. Agafonov1
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
3Almazy Anabar Open Joint-Stock Company, ul. Chernyshevskogo 6, Yakutsk, 677000, Russia
Keywords: Ferroan platinum, mineral inclusions, bowieite, kingstonite, miassite, ore-forming system

Abstract >>
This study is concerned with the typochemical features of heavy-concentrate platinum from diamond placers of the Mayat-Vodorazdel’nyi site in the Anabar River basin. Platinum occurs there as Fe–Pt solid solutions (ferroan platinum of RuRh specialization, ~90%), as well as minor Pd and Irferroplatinum. Among PGE minerals, OsIrRu alloys and chengdeite are revealed. Inclusions of PGE minerals are thoroughly studied, and the scales of their spread, the composition of mineral phases, and the relations between them are determined. Ruthenium-containing highRh ferroplatinum bears a lot of inclusions of RhS composition: Rh-containing PGE thiospinels and sulfides and arsenides of Rh, Ru, and Pt. In lowRh platinum, mineral inclusions are much scarcer and usually form other parageneses. The mineral compositions in the system RhSRu indicate the existence of a long isomorphous series Rh3S4Ru3S4, with the content of Ru3S4 reaching 15 at.%.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.003



4.
MEIMECHITEPICRITE ASSOCIATIONS IN SIBERIA, PRIMORYE, AND KAMCHATKA (comparative analysis and petrogenesis)

Yu.R. Vasilev1,2, M.P. Gora3
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, ul. Pirogova 2, Novosibirsk, 630090, Russia
2Novosibirsk State University
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Meimechitepicrite associations, comparative analysis, geochemistry, petrogenesis

Abstract >>
Analysis of petrochemical and geochemical information on rocks and primary melt inclusions from olivines of meimechite-picrite associations of different ages in Siberia (MaimechaKotui province), Primorye (SikhoteAlin), and Kamchatka was made. It showed that the rocks, despite their similar appearance and identical structural patterns, differ considerably in the contents and distribution of incompatible and rare-earth elements and in the composition and evolution trends of parental high-temperature highly magnesian melts.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.004



5.
THE NEW ORDOVICIAN STAGE STANDARD AS APPLIED TO THE STRATIGRAPHIC UNITS OF THE WESTERN ALTAI-SAYAN FOLDED AREA

N.V. Sennikov1, E.V. Lykova1, O.T. Obut1, T.Yu. Tolmacheva2, N.G. Izokh1
1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
Keywords: Ordovician, new stage standard, biostratigraphy, graptolite and conodont zones, horizon, Altai-Sayan Folded Area

Abstract >>
Data are provided on the new Ordovician stage standard of the International Stratigraphic Chart: Tremadocian, Floian, Dapingian, Darriwilian, Sandbian, Katian, and Hirnantian. Graptolite and conodont zonal and infrazonal successions are used for a precise estimation of the chronostratigraphic position of the boundaries of the previous and newly proposed Ordovician regional stratigraphic units (horizons) in the western Altai-Sayan Folded Area. The chronostratigraphic position of the boundaries of most of the Ordovician formations showing a wide lateral distribution in southern Siberia has been described in detail in terms of the new stage standard of the General Stratigraphic Scale of Russia.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.005



6.
THE ORDOVICIAN MUKTEIAN HORIZON OF THE SIBERIAN PLATFORM: PALEONTOLOGICAL SUBSTANTIATION, DISTRIBUTION, AND CORRELATION OF SECTIONS

O.A. Maslova1, A.G. Yadrenkina1, A.V. Kanygin2
1Siberian Research Institute of Geology, Geophysics and Mineral Resources (SNIIGGiMS), Krasnyi pr. 67, Novosibirsk, 630091, 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
Keywords: Ordovician, regional stratigraphic chart, Mukteian Horizon, correlation, Siberian Platform

Abstract >>
The new-generation regional stratigraphic chart of the Siberian Platform was accepted by the Interdepartmental Stratigraphic Committee of Russia in April 2013. Two main supplements to the chart of 1979 were made: (1) the new scale of stages, accepted by the International Commission on Stratigraphy in 2008, was presented for the Ordovician System along with the previous British standard and (2) the nomenclature of the regional stratigraphic units is supplemented by the Mukteian Horizon, which occupies an intermediate position between the Vikhorevian and Volginian Horizons. The first substantiation of the necessity of viewing this stratigraphic interval as an independent horizon was made in 1980, after it had become possible to use well cores for a more precise definition of the paleontologic characteristics and boundaries of the Vikhorevian Horizon, originally detected from several isolated sections in the Irkut amphitheater with an indistinct boundary with the overlying Volginian Horizon. Recent data, particularly those from drilling, permit a more complete paleontological substantiation of the Mukteian Horizon, consideration of its distribution in different structure-facies zones, and correlation of type sections.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.006



7.
OIL POTENTIAL OF THE LOWER MESOZOIC DEPOSITS OF THE KHAPCHAGAI MEGASWELL OF THE VILYUI SYNECLISE

A.F. Safronov1, A.I. Sivtsev1, V.B. Chernenko2
1Oil and Gas Research Institute, Siberian Branch of the Russian Academy of Sciences, ul. Oktyabrskaya 1, Yakutsk, 677980, Russia
2Sakhatransneftegaz OJSC, ul. Kirova 18, Yakutsk, 677027, Russia
Keywords: Oil shows, oil rim, Vilyui syneclise

Abstract >>
Analysis of all available geological, geophysical, and field data on some gas condensate fields discovered within the Khapchagai megaswell (Vilyui syneclise of the Siberian Platform) as early as the 1960s shows the presence of oil rims in Lower Triassic (horizon T1-III in the Srednevilyuiskoe and Tolonskoe gas condensate fields and horizon T1-Kh in the Mastakhskoe gas condensate field) and Lower Jurassic (horizons J1-I and J1-II in the Mastakhskoe gas condensate field) deposits. The C3 oil reserves in these rims are estimated at several tens of millions of tons of oil. The results are indicative of the oil potential of the Lower Mesozoic deposits not only of the Vilyui syneclise but also of the Lena-Vilyui petroliferous province as a whole, which was always characterized as a gas-bearing province in summary reports.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.007



8.
DIELECTRIC SPECTRA OF WATER–OILSATURATED POROUS MEDIA FOR THE kHz RANGE AND DETERMINATION OF VOLUME FRACTIONS OF SYSTEM COMPONENTS

T.I. Eltsov1, V.N. Dorovsky1, D.N. Gapeev2
1Baker Hughes Incorporated, ul. Kutateladze 4a, Novosibirsk, 630128, Russia
2Immanuel Kant Baltic Federal University, ul. Aleksandra Nevskogo 14, korp. 10, Kaliningrad, 236041, Russia
Keywords: Dielectric spectra, kHz domain, porous medium

Abstract >>
The article presents a novel procedure of finding the water-oil ratio in a saturated porous medium by dielectric spectroscopy. Based on the study of experimental measurements of dielectric permittivity and the dielectric loss factor, it has been established that the dielectric spectrum in the kHz and MHz frequency range of the electromagnetic field in a porous medium saturated with fresh water is a characteristic symmetrical curve, whose symmetry may be distorted when oil is introduced into the system. The type of symmetry, degree of distortion, and corresponding physical mechanisms of polarization enable one to find the water-oil ratio without resorting to the mixture formulae traditionally used for finding the water-oil ratio in Maxwell-Wagner relaxation.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.008



9.
SOFTWARE FOR INVERSION OF TEM DATA AFFECTED BY FAST–DECAYING INDUCED POLARIZATION

E.Yu. Antonov1, N.O. Kozhevnikov1,2, M.A. Korsakov1
1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, 630090, 2, ul. Pirogova, Novosibirsk, Russia
Keywords: - , , ,

Abstract >>
The paper presents new software and stepwise modeling techniques for inversion of TEM data affected by fast-decaying induced polarization (IP). The software and the methods have demonstrated high efficiency when applied to detection of unfrozen ground zones (taliks) in the Pyakyakhinka oilfield and to petroleum exploration in the southern Siberian craton.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.009



10.
GEOLOGIC HAZARDS ASSOCIATED WITH SEISMOGENIC FAULTING IN SOUTHERN SIBERIA AND MONGOLIA: FORMS AND LOCATION PATTERNS

O.V. Lunina, A.V. Andreev, A.A. Gladkov
Institute of the Earths Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
Keywords: Faults, earthquakes, liquefaction, subsidence, secondary surface rupture, slope instability, parameters

Abstract >>
The forms and location patterns of geologic hazards induced by earthquakes in southern Siberia, Mongolia, and northern Kazakhstan in 1950 through 2008 have been investigated statistically, using a database of coseismic effects created as a GIS MapInfo application, with a handy input box for large data arrays. The database includes 689 cases of macroseismic effects from MS = 4.1–8.1 events at 398 sites. Statistical analysis of the data has revealed regional relationships between the magnitude of an earthquake and the maximum distance of its environmental effects (soil liquefaction and subsidence, secondary surface rupturing, and slope instability) to the epicenter and to the causative fault. Thus estimated limit distances to the fault for the MS = 8.1 largest event are 40 km for soil subsidence (sinkholes), 80 km for surface rupture, 100 km for slope instability (landslides etc.), and 130 km for soil liquefaction. These distances are 3.55.6 times as short as those to the epicenter, which are 150, 450, 350, and 450 km, respectively. Analysis of geohazard locations relative to nearest faults in southern East Siberia shows the distances to be within 2 km for sinkholes (60% within 1.5 km), 4.5 km for landslides (90% within 1.5 km), 8 km for liquefaction (69% within 1 km), and 35.5 km for surface rupture (86% within 2 km). The frequency of hazardous effects decreases exponentially away from both seismogenic and nearest faults. Cases of soil liquefaction and subsidence are analyzed in more detail in relation to rupture patterns. Equations have been suggested to relate the maximum sizes of secondary structures (sinkholes, dikes, etc.) with the earthquake magnitude and shaking intensity at the site. As a result, a predictive model has been created for locations of geohazard associated with reactivation of seismogenic faults, assuming an arbitrary fault pattern. The obtained results make basis for modeling the distribution of geohazards for the purposes of prediction and estimation of earthquake parameters from secondary deformation.

DOI: http://dx.doi.org/10.1016/j.rgg.2014.07.010