The article presents an original methodology for constructing a structural model of an oil and gas field, focused on the consistent integration of drilling and seismic data represented in different domains—depth and time. To address the problem of reconciling heterogeneous data, the use of three-dimensional approximation methods—3D splines and joint cokriging—is proposed, within which drilling and seismic data are combined in a single variable space. This approach simplifies the workflow for structural model construction by eliminating the need for explicit generation of average velocity maps or the introduction of corrections to regression relationships. A comparison is also performed of the quality of structural models obtained using the proposed methods—3D spline approximation and joint cokriging—with results produced by traditional approaches, including linear regression and methods based on average velocity maps constructed in various ways. The comparison is based on error analysis using cross-validation techniques. It is shown that the best results are provided by the 3D spline method, which has not previously been applied to structural mapping problems. Comparable accuracy is demonstrated by the traditional approach based on linear regression followed by structural map correction using interpolation and adjustments. The results are demonstrated using the example of modeling the depth of the top of the Bazhenov Formation at the Kazan oil and gas condensate field. The high drilling density made it possible to assess the accuracy of different structural modeling methods under varying levels of well data availability, characteristic of different stages of field development.
1 Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg 2 Saint Petersburg Mining University, St. Petersburg 3 Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk 4 State Key Laboratory of Continental Evolution and Early Life, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi'an
Keywords: LITHOLOGY, FORMATION, REGIONAL STAGE, PALAEONTOLOGY, MICROFOSSILS, STRATIGRAPHY, EAST EUROPEAN PLATFORM, VENDIAN, EDIACARIAN, CAMBRIAN
In order to revise the Upper Vendian and Lower Cambrian stratigraphy in the northwest of Russia, a lithological and paleontological study was conducted for the Geolkom, Taitsy-2, Utkina Zavod'-1 reference drill-core sections in central part of the Baltic-Ladoga monocline of the East European Platform. The strata have been subdivided into the Staraya Russa (Redkino Regional Stage), Vasilevskiy Ostrov (Kotlin Regional Stage), Lomonosov and Siverskaya (Kotlin – undivided Rivne-Lontova Interval) formations. The uppermost Upper Member of the Vasilevsky Ostrov Formation is missing in the Geolkom drill-core stratotype section, where the Kotlin Regional Stage is unconformably overlain by Quaternary deposits. A complete section in the Taitsy-2 drill-core section (depths 318-188 m) is here suggested as a hypostratotype of the Vasilevsky Ostrov Formation. Taking into account that the Lomonosov Formation was erected without a designated stratotype, the further suggest the Taitsy-2 drill-core section (depths 188-126 m) as its lectotype. The Vendian–Cambrian boundary is placed in the mid-section of the Lomonosov Formation Lower Member marked by the Kotlin Fossil Assemblage (strata with Aataenia reticularis - Bicuspidata fusiformis - Vanavarataenia insolita) being replaced by the Rivne-Lontova Fossil Assemblage (strata with Ceratophyton sp. - Teophipolia lacerata). The lowermost Redkino Fossil Assemblage (strata with Tynnia precambrica - Zinkovioides inclusus) hosts elements of the Ediacaran-type acanthomorphic biota (Tanarium aff. T. conoideum, Mengeosphaera sp.), which is not typical for central and western regions of the East European Platform.
A.A. Shchetnikov1,2*, A.Yu. Kazansky1,3, N.E. Berdnikova4, I.M. Berdnikov4, I.A. Filinov1,2, V.V. Ivanova5, G.A. Danukalova6, E.M. Osipova6, F.I. Khenzykhenova7, O.D. Namzalova7, D.G. Malikov8 1Institute of the Earth's Crust, SB RAS, Irkutsk, Russia 2Vinogradov Institute of Geochemistry, SB RAS, Irkutsk, Russia 3Geological Institute, RAS, Moscow, Russia 4Irkutsk State University, Irkutsk, Russia 5Institute of Precambrian Geology and Geochronology, RAS, St. Petersburg, Russia 6Institute of Geology, Ufa Federal Research Centre RAS, Ufa, Russia 7Geological Institute SB RAS, Ulan-Ude, Russia 8Sobolev Institute of Geology and Mineralogy, SB RAS, Novosibirsk, Russia
The paper presents the results of comprehensive study of the section of the multilayered archeological Igetey section (Lower–Upper Paleolithic, Cisbaikalia). For the first time, a geochronological characteristics of the full thickness of the section was obtained based on IR–OSL dating. The sedimentary deposits found at the Igetey geoarcheological section were found to be between 155,000 and 160,000 years old. The stratigraphic sequence of sediments of all isotopic stages of the Upper Pleistocene and Holocene (MIS 5–1), as well as stage 6 of the Middle Pleistocene, was characterized. In terms of lithologic-facial conditions, the Igetey section is represented by a complexly constructed heterogeneous formation of the slope (cryogenic-deluvial-proluvial) and subaerial series with eight horizons with pedogenesis, including modern soil, and seven cultural layers. The upper part of the section (to a depth of 12 meters) reveals the structure of a colluvial fan with aeolian sediments and paleosols. The Middle Pleistocene cover sediments of the coalescing fan are exposed below. This part of the section is represented by a loess-soil sequence, in which a substantial pedocomplex of five paleosols is distinguished, dating to the second half of MIS 6 (135–160 ky BP) and probably recording the early stage of the last Pleistocene interglacial. All paleosols, according to their petromagnetic properties, have a "Siberian" formation mechanism and are characterized by the presence of cryogenic disturbances. Data obtained from studying the species and quantitative diversity of terrestrial and freshwater mollusks made it possible to trace changes in the structure of biotopes and reconstruct the paleoecological conditions in the area of the Igetey section from the Middle to Late Pleistocene. During the formation of the Middle Pleistocene deposits (the second half of MIS 6), the climate was generally moderately cool, with open space biotopes predominating, which were located in the river valley, and at the same time, there were several intervals of climate warming. The enhancement of conditions is recorded during the formation of layers 17, 14, 11, and 9. The climate was moderately warm and humid, and the biotopes of open spaces were supplemented by intermediate ones. The results from the Early Late Pleistocene malacocomplex (MIS 5) indicate a moderate climate in both temperature and humidity (layer 7), followed by a period of cooling (layer 6). During this time, open-space biotopes predominated.
V. V. Babich
V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Science, Novosibirsk, Russia
Keywords: climate, paleo-reconstruction, global warming, anthropogenic factor, greenhouse effect, empirical modeling.
Climate has a huge impact on human living conditions and plays a large role in its history. There are numerous examples of serious social upheavals of local and regional proportions over the past few millennia associated with climate change. Therefore, modern global warming and its causes is one of the most pressing and most controversial issues in both the scientific and public community. In this work, an attempt was made to assess the degree of possible participation of the anthropogenic component in the formation of climate in various regions of the world during the industrial period (since 1850) by analyzing data on the past states of the climate system at a sufficiently long time interval. Using harmonic analysis, empirical models of climate change over time were constructed for these regions. By extrapolating these models to the industrial period, "natural" temperature change scenarios were obtained, taking into account only natural causes and excluding anthropogenic factors. It was found that in all studied regions, instrumentally recorded temperature values significantly exceed the "model" values. On average, during the industrial period, according to "natural" scenarios, air temperature globally should have increased by ~0,02°C, but in reality, the temperature over this time interval increased by ~0,94°C. This deviation began to appear around 1920, gradually intensifying thereafter. These facts can be considered as a manifestation of the anthropogenic factor, which makes a certain contribution to modern global warming.
A.V. Golovin¹, A.A. Tarasov¹ 1Sobolev Institute of
Geology and Mineralogy Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia
Keywords: kimberlites; olivine; xenoliths; sheared peridotites; morphology and variations of olivine composition, Udachnaya-East pipe; Siberian Craton.
Olivine is the major rock-forming mineral in kimberlites, and the results of numerous studies of kimberlitic olivine are widely used in most models of kimberlite petrogenesis. The composition of olivine from kimberlites is also applied in reconstructions of the composition, structure, and evolution of the lithospheric mantle beneath ancient cratons. However, a persistent problem is the identification of magmatic olivine in kimberlites and olivine derived from disaggregated mantle xenoliths, as both may display very similar morphologies. In this study, based on extensive empirical material (more than 500 olivine grains up to 5 mm in size from a single phase of volcaniclastic kimberlite of the Udachnaya-East pipe, Siberian craton) and on a compilation of previously obtained data on olivine compositions from 158 xenoliths of sheared peridotites from the same kimberlite body, we demonstrate that although the morphology of these olivines may be similar, they can be distinguished using compositional and internal structural criteria. This study also presents new data on olivine compositions from microxenoliths (20 samples) of sheared peridotites. The Mg# distribution of olivine in microxenoliths is bimodal, defining two compositional groups with Mg# ranges of 89.5–92.5 (50% of samples) and 84.5–87.5 (45% of samples), whereas olivine from xenoliths of deformed peridotites shows a unimodal Mg# distribution in which the majority of compositions (80% of samples) fall within the Mg# range of 89.5–92.5. The study presents a series of well-documented examples where olivine neoblast grains derived from disaggregated mantle xenoliths of sheared peridotites clearly acted as seeds for the growth of magmatic olivine. In addition, a unique example is described of the destruction of a microxenolith of sheared peridotite during kimberlite crystallization, manifested by the compact occurrence of non-resorbed and unzoned euhedral neoblast crystals within a 1 mm field of view in the kimberlite matrix. The largest proportion of true kimberlitic olivine occurs in the groundmass size fraction (<0.25 mm) of unaltered rocks; however, olivine of this size fraction in kimberlites worldwide remains essentially unstudied.
B.B. Kochnev1,2, N.I. Vetrova2, A.I. Proshenkin2 1Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia
2Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk,Russia
Keywords: Mana Trough, East Sayan, Late Precambrian, carbonaceous sediments geochemistry, C-isotope chemostratigraphy, detrital zircon geochronology, sedimentation settings
The chemical and isotope (C and O) composition of carbonate deposits and the age distribution of detrital zircon grains from the Late Precambrian sequences of the Mana Trough from Sayan Segment of the Central-Asian Mobile Belt (CAMB) were studied. Limestones of volcanic-sedimentary Kuvai Group (Mana and Bakhta Formations) formed in open-ocean conditions have highly positive δ13C values and, with another data, allow to limit their age as Late Riphean, оr Late Tonian. Angaloy Horizon strata have near-zero or slightly positive δ13C values, and minimal detrital zircon ages about 580 Ma, allowing to resemble it to Upper Vendian (or Upper Ediacaran). In the upper part of the Anastas’ino Horizon, two pronounced positive δ13C excursions was found, contrasting to sub-zero values, and marking the base of the Cambrian Tommotian Stage. Detrital zircon age spectra from the Angaloy and lower Anastas’ino Horizons demonstrate two Neoproterozoic populations with 710 and 630 Ma peaks. Possible sources for these zircons ages are volcanic and granitoid complexes coming from Sayan segment of the CAMB. Judging from occurrence of Paleoproterozoic zircon age population in the studied sequences, complete accretion of sedimentary basin of the Mana Trough to Siberian Craton was completed at Early Cambrian. These conclusions verified by geochemical indicators of sedimentation settings and by geodynamic reconstructions from the adjacent regions.
A.M. Soldatenko1, M.S. Sudakova2, 3 1Institute of Geography of the Russian Academy of Sciences, Moscow, Russia 2Lomonosov Moscow State University, Moscow, Russia 3Earth Cryosphere Institute, Tyumen Scientific Center, Siberian Branch of the Russian Academy of Sciences, Tyumen, Russia
This article discusses the development of a methodology for creating a semi-synthetic dataset to train a neural network for the detection and segmentation of hyperbolic diffractions in ground-penetrating radar (GPR) data. The proposed method offers a solution by generating annotated data where target synthetic objects are placed onto real background sections that are confirmed to be free of the target objects. This approach enables model fine-tuning without direct manual labeling for any specific survey type. The final algorithm was successfully validated on GPR data from the Austre Grønfjordbreen. This solution will significantly simplify the analysis of the internal structure of polythermal glaciers and allow us to assess their hydrothermal structure.
K.Yu. Vasileva1,2, M.A. Rogov1,3, V.A. Zakharov 1, B.L. Nikitenko 4, E.B. Pestchevitskaya 4,
A.V. Yadrenkin4, N.K. Lebedeva4, A.A. Goryacheva4, S.N. Khafaeva4, N.A. Malyshev5, V.E. Verzhbitsky5, G.V. Ulyanov6, V.V. Obmetko5, A.A. Borodulin5 1Geological institute of RAS, Moscow, Russia 2Saint Petersburg State University, St. Petersburg, Russia 3Arctic Research Center (ARC), Moscow, Russia 4The Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences (IPGG SB RAS), Novosibirsk,Russia 5Rosneft, Moscow, Russia 6JSC “RN-GIR” Moscow branch – center for technical competentions IGIRGI, Moscow, Russia
We present data on the findings of glendonites (pseudomorphs of the cold-water mineral ikaite) in Permian, Jurassic and Lower Cretaceous sedimentary rocks, penetrated by well KS-1, drilled on the coast of the Laptev Sea. This is the only section in the world that contains glendonites of both Paleozoic and Mesozoic age, belonging to a vast time interval including three geological systems. Glendonites are found here in all stages from which they are known in northern Siberia, with the exception of those stratigraphic intervals in which glendonite finds are comparatively rare (Oxfordian, Ryazanian and Valanginian stages). KS-1 well is a unique natural archive, which reflects the most significant cooling events in the studied region during the late Paleozoic-Mesozoic.
B.B. Kochnev1,2, N.I. Vetrova2, E.V. Vetrov3, G.A. Karlova1 1Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia 2Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk,Russia 3PJSC Polyus, Moscow, Russia
Keywords: Vendian, Cambrian, Ediacaran, Gorny Altai, Baratal Group, carbonate sedimentary rocks, geochemistry, carbon, oxygen and strontium isotopes, metasomatosis
The chemical and isotope (C, O, Sr) composition of carbonate deposits in three sections of the lower Baratal Group in the southeast of the Altai Mountains, which are considered as one of the oldest known fragments of the carbonate cover of oceanic uplifts preserved in the structure of the Central Asian folded belt, was studied. The contents of Fe, Mn and Sr and their ratios to each other, and to isotope parameters indicate a post-sedimentary alteration which varying within and between studied sections. For the least altered «Akkaya» section, the δ13C values are –0.4…+0.7‰, and the 87Sr/86Sr ratios vary from 0.70818 to 0.70833, which limits the age of sedimentation to the range of 550-520 Ma. In the «Kurai» and «Chagan-Uzun» sections, along with similar values, anomalously low values of 87Sr/86Sr down to 0.70662…0.70701 are observed, which are often accompanied by a decrease in δ18O values and an increase in Mn content. These unusual characteristics of carbonates are proposed to be the result of influence of the metasomatic fluids tied with underlying basalts and spatially related to Kuvai regional fault zone. In the «Kurai» section, skeletal small-shelly fossils Cambrotubulus were found, which are not known to be older than 550 Ma, and confirms the transitional terminal Precambrian – earliest Phanerozoic age of the basal sequences of Baratal Group.
I.F. Chayka1, S.Yu. Stepanov 2, A.V. Kozlov3, F.D. Sandalov4, R.S. Palamarchuk2, N.I. Baykov1, V.S. Zhdanova5, V.D. Abramova4 1Korzhinskii Institute of Experimental Mineralogy RAS, Chernogolovka, Russia ivanlab211@gmail.com 2Natural science museum of the Ilmeny Reserve, Southern Ural center for mineralogy and geoecology UB RAS, Miass, Russia 3Saint Petersburg Mining University of Empress Catherine II, Saint-Petersburg, Russia 4Institute of geology of ore deposits, petrography, mineralogy and geochemistry RAS, Moscow, Russia 5Zavaritsky Institute of Geology and Geochemistry UB RAS, Ekaterinburg, Russia
Keywords: skarn, Cu-Fe skarn formation, native gold, gabbro, S isotopes, Ural Platinum Belt
Skarn-type Fe and Cu deposits enriched in Au are widespread within the Tagil–Magnitogorsk megazone of the Ural Fold Belt and are primarily associated with felsic to intermediate intrusions. In the Northern Urals, Fe–Cu skarn-type deposits and ore occurrences are found in the exocontacts of gabbroic phases of the polyphase intrusions of the Ural Platinum Belt. These systems are of particular interest as they represent the terminal (hydrothermal–metasomatic) stage in the fractionation of chalcophile and noble metals within magmatic systems of young island arcs. The metasomatic rocks developed in the exocontact zone of the Knyaspa intrusion, investigated in this study, contain ore-grade concentrations of Fe and Cu (0.5–5 wt%) and Au (0.2–14 g/t), and are classified as belonging to the Cu–Fe skarn formation of the Ural belt. The geological, mineralogical, and geochemical characteristics of this occurrence are largely typical of Cu–Au skarn deposits and are genetically linked with the gabbroic phase of the intrusion, rather than with the dioritic one. The metasomatic rocks formed after andesibasalts of the Pavda Formation. The following sequence of their formation has been reconstructed: (1) amphibole–plagioclase or clinopyroxene–plagioclase hornfelses (hornfels phase); (2 epidote-bearing assemblages with clinopyroxene or garnet (pre-ore skarn stage of the hydrothermal-metasomatic phase); (3) clinopyroxene–actinolite–epidote associations with magnetite and Cu sulfides (ore skarn stage of the hydrothermal-metasomatic phase); (4) largely zeolite assemblages (late hydrothermal stage of the hydrothermal-metasomatic phase) and (5) supergene phase. The estimated temperatures for the formation of primary sulfide mineralization range from 300 to 400 °C. Formation of native gold, which has exclusively broad compositional range in terms of Cu and Ag admixtures, took place at lower temperatures (approximately 100–250 °C) and probably continued during supergene phase Based on δ34S values in sulfides and the geochemistry of chalcophile elements in skarns, the ore elements were probably orthomagmatic. However, the mobilization of S and Cu from the volcanogenic massive sulfide deposits of the Shemur Formation through their assimilation by the intrusion cannot be ruled out, as well. Regardless of the source, the redox state of sulfur was significantly shifted toward oxidized species (S⁶⁺ or S⁴⁺), resulting in unusually low δ³⁴S values (–6 to –4‰) in the sulfides of the metasomatic rocks.
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