Olga Obut

Olga Obut
Russian Academy of Sciences | RAS

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92
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Publications

Publications (92)
Article
The paper focuses on presumable sources of coarse carbonate material transported into the Visean Northern Kharaulakh basin. The sand to pebble components of the Krestyakh conglomerate unit originated by medium and distant transport by debris flows (turbidity currents) along submarine canyons from the place of their initial littoral deposition to re...
Article
The paper presents first high-precision data, U-Pb detrital zircon ages, whole-rock geochemistry, Hf-in-zircon and whole-rock Nd isotopes, from pre-Devonian (Ediacaran and Silurian) clastic sediments (sandstones) of the Tamdytau, Bukantau and Nuratau mountainous ranges of the Kyzylkum Desert and Nuratau Range in the western Uzbek Tienshan. The sedi...
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The detailed study of the Guryanovka Formation key sections at the northeast of Gorny Altai (Biya and Bura sections) for the first time revealed the representative collection of conodonts. The conodont fauna is composed of 12 species belong to 9 genera: Belodina compressa (Branson and Mehl, 1933), Phragmodus undatus Branson and Mehl, 1933, Panderod...
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—The paper presents new data on the upper Silurian litho- and biostratigraphy of the Gorny Altai area. Sediments within this interval store a succession of taxonomically representative middle–upper Ludfordian, lower Pridoli, and Lower Devonian (Lochkovian–Pragian) conodont assemblages. The new fauna constraints made a basis for updated correlations...
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Study of the Ordovician sedimentary sequences of Gorny Altai and Salair has revealed lithological and paleontological features correlating with global sedimentary events: (1) The Acerocare Regressive Event (an initial event in the Early Tremadocian); (2) Black Mountain Transgressive Event (Early Tremadocian); (3) Peltocare Regressive Event (Tremado...
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This paper presents first U–Pb detrital zircon ages, major and trace element geochemical data and whole-rock Nd and Hf-in-zircon isotope data from sandstones of the Char and Zharma zones of eastern Kazakhstan. Petrographically the sandstones represent greywackes. The U–Pb ages of detrital zircons show unimodal distributions peaked at 345–340 and 33...
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The origin and biostratigraphic constraints of the Krestyakh conglomerate remain among most controversial issues in the Late Paleozoic history of the Northern Kharaulakh basin. The Krestyakh conglomerate is a sequence of coarse sand to pebble-size sediments at the base of the Late Paleozoic Verkhoyansk clastic complex. According to geological, lith...
Article
The Tekturmas ophiolite belt of central Kazakhstan is located in the western Central Asian Orogenic Belt. It consists of three structural‐formational zones: Tekturmas (centre), Bazarbai (north), and Sarysui (south). The Tekturmas zone includes igneous and sedimentary rocks of Karamurun, Tekturmas, and Sarytau formations, which are dominated by volc...
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The Vendian-Cambrian transitional strata of the Igarka Uplift (northwestern Siberian Platform), originally erected as the Sukharikha Formation, are one of the key objects revealing evolution of marine ecosystems in the late Vendian. Herein we describe dwelling burrows Skolithos and Arenicolites from dolostones in the middle Sukharikha Formation (Ne...
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The Itmurundy zone of the northern Balkhash area is a Pacific-type orogenic belt. It possesses a complex geological structure and hosts rocks of mantle, accretionary and post-orogenic associations. The volcanic and sedimentary rocks of the accretionary association belong to three suites: Itmurundy (O1-2), Kazyk (O2-3) and Tyuretai (O3-S1). The suit...
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This paper discusses the structure and facies variability of the Silurian mixed terrigenous-carbonate strata and presents new paleontological and biostratigraphic data. It attempts to refine the stratigraphic position and provide new lithologic evidence (markers) for regional manifestations of global sedimentary events (Mulde transgressive-regressi...
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Recent data on the Ordovician biostratigraphy of the West-Siberian Geosyncline are discussed. The new Regional unit - Pavlov Horizon and two new local sequences – Zapadno-Novogodnyaya Unit and Lekosskaya Unit were defined.
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Pacific-type orogens (fold belts) hosting accretionary complexes are places keeping records of the evolution of paleo-oceans, and formation and transformation of continental crust at their active convergent margins. Pacific-type orogeny induces destruction of crustal materials, their subduction to the deep mantle, generation of hydrouscarbonated pl...
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На западе от северной части Телецкого озера ордовикские, преимущественно терригенные осадочные последовательности слагают достаточно крупные по площади выходы. Геологическое строение этой Прителецкой части Горного Алтая недостаточно изучено, что обусловлено труднодоступностью территории, крайне низкой обнаженностью, отсутствием государственных геол...
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На западе от северной части Телецкого озера ордовикские, преимущественно терригенные осадочные последовательности слагают достаточно крупные по площади выходы. Геологическое строение этой Прителецкой части Горного Алтая недостаточно изучено, что обусловлено труднодоступностью территории, крайне низкой обнаженностью, отсутствием государственных геол...
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Comprehensive lithofacies and biofacies analysis provided constraints on the origin of Upper Ordovician clastic and carbonate deposits in northeastern Gorny Altai, which form large low-elevated flat carbonate banks located relatively close to the shore. The sediments were deposited during the Sandbian and early-middle Katian stages, according to ne...
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This paper discusses the fossil record, stratigraphy and sedimentary environments of lower Cambrian sequences that crop out in the Salair and Gorny Altai, southern part of western Siberia (Russia). Numerous and well-preserved archaeocyaths and a few small shelly fossils (SSF) have been discovered in carbonate sequences that crop out nearby the Gavr...
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The Taidon and Fomin formations of the Kuznetsk Basin (SW Siberia, Russia) were sampled in three sections, Old Belovo quarry, Artyshta village and Starobachaty village. The carbonate beds revealed microfacies of bioclastic wackestone and packstone, deposited in the distal parts of inner ramps and the proximal parts of mid ramps. Relatively rare plu...
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We summarize data on the biostratigraphic units of the Siberian Ordovician deposits based on pelagic groups of fauna: graptolites, conodonts, and chitinozoans. It is shown that graptolite and conodont zones and beds have a high potential for correlation. We have determined the precise zonal position of most of the lower boundaries of the Ordovician...
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This paper presents revised data on Silurian conodonts, graptolites and vertebrates of southern Siberia. We define patterns of facies associations of agnathans and fishes from Silurian basins of the Tuva region in southern Siberia based on original and published data. The agnathans display a mosaic distribution: Tuvaspis margaritae Obruchev plus Ta...
Article
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 chrono- stratigraphic position of the boundaries of the previous and newly p...
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The presence of one of the oldest records of polycystine Radiolaria in the Lower Cambrian sedimentary sequence of the Ak-Kaya section (Gorny Altai) requires a biostratigraphic dating. The trilobites found recently a few tens of meters below the radiolarian-bearing level belong to Calodiscus resimus Repina, Serrodiscus fossuliferus Repina and Alacep...
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The paper presents the first data on geochemistry (major and trace elements, isotopes) of the Late Devonian-Early Carboniferous basalts of the Char suture-shear zone in East Kazakhstan, and includes detailed analysis of their geological relations and petrogenesis (fractional crystallization/melting modeling). Three groups of oceanic basalts coexist...
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Relatively well-preserved polycystine Radiolaria are here described from Lower Cambrian (Botomian) strata of the Shashkunar Formation, Altai Mountains in southern Siberia (Russia). These radiolarians display a test formed of a disorderly and three-dimensionally interwoven meshwork of numerous straight and curved bars branching from a five-rayed poi...
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Estimating the paleobasin depth is one of the most difficult problems in studying the evolution of sedimentation. Considerable depth variations in ocean and shelf paleobasins are due not only to their origin but also to the evolution of their large constituents owing to the differentiation of the dissected bottom. The Early Paleozoic volcanic-sedim...
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Four well-preserved radiolarian associations recovered from the uppermost Givetian–upper Frasnian siliceous strata of the Zolotukha and Gryaznukha formations near Gornyak Settlement in the Altai-Sayan Folded Area (ASFA) in the South West Rudny Altai, southwestern Siberia, eastern Russia, are represented by 26 species assigned to 11 genera incl...
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Facies zonation of the Paleozoic basement of West Siberian geosyncline and its surroundings is presented. Facies megazones are distinguished according to types of sedimentation. Analysis of lateral and successive sedimentary sequences shows that the available data are insufficient to map the facies distribution over the whole territory of the geosy...
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The siliceous rocks from structures of the junction zone of the Kokchetav massif and Stepnyak trough that occur in turbidites of the accretionary wedge, silica-volcanogenic sequence of the Stepnyak trough and syntectonic olistostrome were dated on the basis of findings of conodonts and radiolarians within the Middle-Upper Arenigian (conodont zones...
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Cambrian events in the history of the different terranes comprising mosaic-block geological structures of the Altai-Sayan Folded Area is discussed. On the basis of the complex analysis of the paleontological, lithological and paleomagnetic data, the probable territorial proximity of the Biya-Katun' (Gorny Altai) and Bateny (Kuznetsky Alatau) blocks...
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Upper Cambrian-Lower Ordovician volcanic-siliceous-terrigenous strata of the Zasur'ya Group belonging to the Gorny Altai segment of the Paleo-Asian Ocean are considered in this paper. The Gorny Altai segment developed over a long period, of not less than 25–30 million years. The Zasur'ya Group consists of the Listvenny, Talitsa and Marcheta Formati...
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The geologic structure, geochemistry, lithology, and paleontology of the Late Cambrian-Early Ordovician volcanosedimentary Zasur'ya Group in Gorny Altal are considered. Its geochemical parameters, lithologic features, and biomarkers are indicative of its oceanic genesis. The regularities of the spatial distribution of various facies types of Zasur'...