А.V. Alatortsev, А.N. Kolesnik, X. Shi, L. Hu, V. Karnaukh, А.S. Astakhov
––Cores of Holocene bottom sediment collected in the East Siberian Sea revealed layers with mixed textures and layers with breaks in sedimentation corresponding to the two sea levels defined as modern (upper) and Early Holocene (lower). The layers are characterized by distinctly chaotic variability in textural pattern (mottled appearance, multidirectional banding), colorimetric and geochemical parameters (sawtooth-like distribution curves). Such character of changes is associated with the physical action of dragging keels of ice/icebergs exerted on the seafloor and is referred to as ice gauging (scouring). Its analysis can be used for identification of ice scour-affected layers in other sediment cores collected in this region, and for the purpose of creating a representative database, predicting their occurrence and developing adequate measures to minimize the damaging impact from drifting sea ice and icebergs on the seafloor within the bounds of the Arctic shelf.
{"title":"Lithological and Geochemical Indicators of Ice Gouging: Evidences from Holocene Sediments in the East Siberian Sea","authors":"А.V. Alatortsev, А.N. Kolesnik, X. Shi, L. Hu, V. Karnaukh, А.S. Astakhov","doi":"10.2113/rgg20234528","DOIUrl":"https://doi.org/10.2113/rgg20234528","url":null,"abstract":"\u0000 ––Cores of Holocene bottom sediment collected in the East Siberian Sea revealed layers with mixed textures and layers with breaks in sedimentation corresponding to the two sea levels defined as modern (upper) and Early Holocene (lower). The layers are characterized by distinctly chaotic variability in textural pattern (mottled appearance, multidirectional banding), colorimetric and geochemical parameters (sawtooth-like distribution curves). Such character of changes is associated with the physical action of dragging keels of ice/icebergs exerted on the seafloor and is referred to as ice gauging (scouring). Its analysis can be used for identification of ice scour-affected layers in other sediment cores collected in this region, and for the purpose of creating a representative database, predicting their occurrence and developing adequate measures to minimize the damaging impact from drifting sea ice and icebergs on the seafloor within the bounds of the Arctic shelf.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43264293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
––This paper describes a three-dimensional inversion of magnetovariational tippers calculated for the Dalat observatory in South Vietnam on the basis of the geomagnetic variation records obtained from the INTERMAGNET network. The frequency dependences of the tippers are inverted using the ModEM software, which makes it possible to construct a geoelectric model of the Dalat zone in a 300 × 300 × 150-km spatial region (x, y, and z axes, respectively) with its center located at the observatory. The resulting model of the geoelectric section contains both surface and deep conductive blocks located at the top and bottom of the Earth’s crust and in the upper mantle. The central part of the upper local conducting block with a resistivity of 0.5–1.0 Ohm⋅m is located near the observatory at a depth of 12–14 km. A more massive conductive block is located to the east of the observatory in the coastal region. Its central part with a resistivity of 0.3 Ohm⋅m is located at a depth of 24–28 km and extends under the continent along the coast for about 80 km. The roots of this block are visible to depths of ~100 km in the South China Sea shelf region. It is assumed that the high electrical conductivity of these blocks is provided by melting in the presence of aqueous fluids and granite series rocks, which are widely distributed in the Dalat zone. The crystallization depths of the samples of these granites estimated from the geothermobarometry data are close to the depth intervals of conductive blocks in the model section, which was also observed in the interpretation of magnetotelluric soundings in Southern Tibet, where granitoid rocks are widespread.
{"title":"Magnetovariational Sounding in South Vietnam according to the Dalat Observatory Data","authors":"S. Starzhinskii","doi":"10.2113/rgg20224481","DOIUrl":"https://doi.org/10.2113/rgg20224481","url":null,"abstract":"\u0000 ––This paper describes a three-dimensional inversion of magnetovariational tippers calculated for the Dalat observatory in South Vietnam on the basis of the geomagnetic variation records obtained from the INTERMAGNET network. The frequency dependences of the tippers are inverted using the ModEM software, which makes it possible to construct a geoelectric model of the Dalat zone in a 300 × 300 × 150-km spatial region (x, y, and z axes, respectively) with its center located at the observatory. The resulting model of the geoelectric section contains both surface and deep conductive blocks located at the top and bottom of the Earth’s crust and in the upper mantle. The central part of the upper local conducting block with a resistivity of 0.5–1.0 Ohm⋅m is located near the observatory at a depth of 12–14 km. A more massive conductive block is located to the east of the observatory in the coastal region. Its central part with a resistivity of 0.3 Ohm⋅m is located at a depth of 24–28 km and extends under the continent along the coast for about 80 km. The roots of this block are visible to depths of ~100 km in the South China Sea shelf region. It is assumed that the high electrical conductivity of these blocks is provided by melting in the presence of aqueous fluids and granite series rocks, which are widely distributed in the Dalat zone. The crystallization depths of the samples of these granites estimated from the geothermobarometry data are close to the depth intervals of conductive blocks in the model section, which was also observed in the interpretation of magnetotelluric soundings in Southern Tibet, where granitoid rocks are widespread.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48656535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Sokol, O.A. Koz’menko, A. Kruk, S. F. Nechepurenko
––The composition of the fluid in carbonate- and chlorine-bearing pelite was experimentally studied at 3.0 GPa and 750 and 900 ºC, using the diamond trap method. The results of inductively coupled plasma atomic-emission spectrometry (ICP AES) and mass balance calculations showed that a supercritical fluid formed in the studied system at 3.0 GPa and 750 °C. The fluid is Si- and Al-rich and contains 30–50 wt.% H2O + CO2 and up to 1 wt.% Cl. The contents of other major elements decrease in the order: K > Na > Сa ≈ Fe > Mg > Mn > Ti ≈ P. Compared with supercritical fluids appeared in the systems pelite–H2O and eclogite–H2O, the fluid with high CO2 and Cl contents is richer in Fe, Ca, Mg, and Mn but poorer in Si. Silicate melt generated in this system at 900 ºС has a composition typical of pelitic melt. Our experiments reveal a set of fingerprints of element fractionation between a supercritical fluid and solids forming an eclogite-like association, namely, high mobility of P, Sr, and B and low mobility of Li and S. Thus, a supercritical fluid compositionally similar to the pelitic melts generated in subduction zones can transfer significant amounts of both volatiles (H2O, CO2, Cl, and P) and major components to the regions of arc magma generation. It is important that supercritical fluids should have trace element signatures of diluted low-temperature fluids.
{"title":"Composition of the Fluid in Carbonate- and Chlorine-Bearing Pelite near the Second Critical Point: Results of Diamond Trap Experiments","authors":"A. Sokol, O.A. Koz’menko, A. Kruk, S. F. Nechepurenko","doi":"10.2113/rgg20234555","DOIUrl":"https://doi.org/10.2113/rgg20234555","url":null,"abstract":"\u0000 ––The composition of the fluid in carbonate- and chlorine-bearing pelite was experimentally studied at 3.0 GPa and 750 and 900 ºC, using the diamond trap method. The results of inductively coupled plasma atomic-emission spectrometry (ICP AES) and mass balance calculations showed that a supercritical fluid formed in the studied system at 3.0 GPa and 750 °C. The fluid is Si- and Al-rich and contains 30–50 wt.% H2O + CO2 and up to 1 wt.% Cl. The contents of other major elements decrease in the order: K > Na > Сa ≈ Fe > Mg > Mn > Ti ≈ P. Compared with supercritical fluids appeared in the systems pelite–H2O and eclogite–H2O, the fluid with high CO2 and Cl contents is richer in Fe, Ca, Mg, and Mn but poorer in Si. Silicate melt generated in this system at 900 ºС has a composition typical of pelitic melt. Our experiments reveal a set of fingerprints of element fractionation between a supercritical fluid and solids forming an eclogite-like association, namely, high mobility of P, Sr, and B and low mobility of Li and S. Thus, a supercritical fluid compositionally similar to the pelitic melts generated in subduction zones can transfer significant amounts of both volatiles (H2O, CO2, Cl, and P) and major components to the regions of arc magma generation. It is important that supercritical fluids should have trace element signatures of diluted low-temperature fluids.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49237051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
––The leading role of lithostratigraphic, structural/tectonic, magmatic, metamorphic, and fluid geologic factors in the formation of a graphite deposit is substantiated. We present the petrographic and chemical compositions of rocks and minerals of igneous rocks, the δ13С values of graphites and calcitites, the δ18O values of carbonates, the δ34S values of sulfides, and the 87Sr/86Sr and 87Rb/86Sr ratios in calcitites and microdolerite injections. The thermal effect of magmatic melt on coal led to its degassing and graphitization. The steaming of microdolerite injections with hydrocarbon fluids was probably accompanied by the removal of iron from them and the crystallization of low-Fe clinopyroxene, and the interaction of fluids with basaltic melt in the upper endocontact zone of the intrusion led to the segregation of the melt and the formation of a globular structure of rocks. The presence of a calcitite lens and a sulfide vein between the roof of the intrusion and the graphite bed is due to the earlier intrusion of sulfate salt melt and its subsequent interaction with hydrocarbon fluids, which resulted in sulfate reduction and the formation of calcitites. The sulfate reduction terminated with iron sulfurization in the basaltic melt and the formation of a sulfide vein. Sulfate salt melt was a source of heavy sulfur isotope (δ34S = 14.9–17.5‰) for sulfides and of calcium for calcitites. The similar isotope compositions of calcitites (δ13СPDB = –22.5 to –23.5‰), coals (–22.6 to –25.5‰, n = 25), and graphites (–23.5 to –25.0) suggest that coal is a source of carbon for calcitites. In the isotopic compositions of strontium (87Sr/86Sr ≈ 0.70834–0.70885) and oxygen δ18O ≈ 15‰) the calcitites are similar to the Devonian evaporites of the Siberian Platform. The isotope data (δ34S, δ18O, δ13С, and 87Rb/86Sr) point to the participation of the coal seam and anhydrite as sources of substance in the formation of calcitite and sulfide mineralization.
{"title":"Petrology of the Kureika Graphite Deposit in the Roof of the First-Rapid Trap Intrusion (Siberian Platform)","authors":"V. V. Ryabov, V. Ponomarchuk","doi":"10.2113/rgg20234492","DOIUrl":"https://doi.org/10.2113/rgg20234492","url":null,"abstract":"\u0000 ––The leading role of lithostratigraphic, structural/tectonic, magmatic, metamorphic, and fluid geologic factors in the formation of a graphite deposit is substantiated. We present the petrographic and chemical compositions of rocks and minerals of igneous rocks, the δ13С values of graphites and calcitites, the δ18O values of carbonates, the δ34S values of sulfides, and the 87Sr/86Sr and 87Rb/86Sr ratios in calcitites and microdolerite injections. The thermal effect of magmatic melt on coal led to its degassing and graphitization. The steaming of microdolerite injections with hydrocarbon fluids was probably accompanied by the removal of iron from them and the crystallization of low-Fe clinopyroxene, and the interaction of fluids with basaltic melt in the upper endocontact zone of the intrusion led to the segregation of the melt and the formation of a globular structure of rocks. The presence of a calcitite lens and a sulfide vein between the roof of the intrusion and the graphite bed is due to the earlier intrusion of sulfate salt melt and its subsequent interaction with hydrocarbon fluids, which resulted in sulfate reduction and the formation of calcitites. The sulfate reduction terminated with iron sulfurization in the basaltic melt and the formation of a sulfide vein. Sulfate salt melt was a source of heavy sulfur isotope (δ34S = 14.9–17.5‰) for sulfides and of calcium for calcitites. The similar isotope compositions of calcitites (δ13СPDB = –22.5 to –23.5‰), coals (–22.6 to –25.5‰, n = 25), and graphites (–23.5 to –25.0) suggest that coal is a source of carbon for calcitites. In the isotopic compositions of strontium (87Sr/86Sr ≈ 0.70834–0.70885) and oxygen δ18O ≈ 15‰) the calcitites are similar to the Devonian evaporites of the Siberian Platform. The isotope data (δ34S, δ18O, δ13С, and 87Rb/86Sr) point to the participation of the coal seam and anhydrite as sources of substance in the formation of calcitite and sulfide mineralization.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46065957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
—The paper presents the results of the study of organic geochemistry of carbonate rocks, silicites, and calcareous mudstones of the Vendian (Ediacaran) Khatyspyt Formation in the northeast of the Siberian Platform. The distribution of dispersed organic matter (OM) is shown to be uneven. The formation comprises carbonate-dominated intervals depleted in OM, with total organic carbon content (TOC) < 0.1%, or weakly enriched in OM (TOC up to 0.4%), interstratified with carbonate-shale, carbonate-shale-siliceous, carbonate-siliceous and siliceous intervals enriched in OM (TOC up to 1–4%). There is also a thin-layered calcareous mudstones anomalously enriched in OM (black shales with TOC at 10%) cropping out in the Khorbusuonka River valley (unit thickness 10 cm). The redox conditions in the water column varied during deposition of the Khatyspyt Formation. Certain intervals characterize a stratified water column and euxinic bottom water conditions. During the study, the assessment was conducted of the OM catagenesis and the generative potential of the Khatyspyt Formation. Based on the results of geochemical study and the synthesis of information on the geological structure of sedimentary succession in the northeastern Siberian Platform, the Khatyspyt Formation has been evaluated as one of the hydrocarbon sources for the territory.
{"title":"Organic Geochemistry of Carbonate Rocks, Silicites and Black Shales of the Vendian (Ediacaran) Khatyspyt Formation, Northeastern Siberia","authors":"D. Melnik, T. Parfenova, D. Grazhdankin, V. Rogov","doi":"10.2113/rgg20224527","DOIUrl":"https://doi.org/10.2113/rgg20224527","url":null,"abstract":"\u0000 —The paper presents the results of the study of organic geochemistry of carbonate rocks, silicites, and calcareous mudstones of the Vendian (Ediacaran) Khatyspyt Formation in the northeast of the Siberian Platform. The distribution of dispersed organic matter (OM) is shown to be uneven. The formation comprises carbonate-dominated intervals depleted in OM, with total organic carbon content (TOC) < 0.1%, or weakly enriched in OM (TOC up to 0.4%), interstratified with carbonate-shale, carbonate-shale-siliceous, carbonate-siliceous and siliceous intervals enriched in OM (TOC up to 1–4%). There is also a thin-layered calcareous mudstones anomalously enriched in OM (black shales with TOC at 10%) cropping out in the Khorbusuonka River valley (unit thickness 10 cm). The redox conditions in the water column varied during deposition of the Khatyspyt Formation. Certain intervals characterize a stratified water column and euxinic bottom water conditions. During the study, the assessment was conducted of the OM catagenesis and the generative potential of the Khatyspyt Formation. Based on the results of geochemical study and the synthesis of information on the geological structure of sedimentary succession in the northeastern Siberian Platform, the Khatyspyt Formation has been evaluated as one of the hydrocarbon sources for the territory.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48242769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Korago, N. Stolbov, M. Burnaeva, I. M. Vasil’eva
—The Novaya Zemlya Archipelago is an early Cimmerian folded structure located on the northern periphery of the Ural–Mongolian fold belt. The geologic development of the archipelago is well-studied and serves as a benchmark for interpolating its features to the shelf of the surrounding water areas, whose sedimentary cover contains large accumulations of hydrocarbon raw materials. In addition to the stratified section of essentially sedimentary rocks, it is of interest to study igneous formations, which clearly mark tectonic events in the geologic history of the archipelago. In the light of this, the age of these formations remains important. The age of some magmatic complexes of the archipelago is still debatable. This paper focuses upon a lamprophyre complex in the extreme south of Novaya Zemlya, which has been dated at the Late Proterozoic or Late Proterozoic–early Paleozoic(?) until recently. The results obtained for the U–Pb age of apatites contained in the rocks of this complex confirm the Devonian age of the lamprophyres, and it is suggested by estimates based on the presented data that the emplacement time lies in a range from 360 to 398 Ma. This means that they might be associated with riftogenic processes on Novaya Zemlya since the second half of the Early Devonian, when the stage of short-term stable carbonate sedimentation (in the first half of the Devonian Period) was replaced by the initiation of a new structural–formational zonal sequence.
{"title":"Lamprophyres of the Southern Coast of Novaya Zemlya: Composition, Tectonomagmatic Position, and New Age Data","authors":"E. Korago, N. Stolbov, M. Burnaeva, I. M. Vasil’eva","doi":"10.2113/rgg20224456","DOIUrl":"https://doi.org/10.2113/rgg20224456","url":null,"abstract":"\u0000 —The Novaya Zemlya Archipelago is an early Cimmerian folded structure located on the northern periphery of the Ural–Mongolian fold belt. The geologic development of the archipelago is well-studied and serves as a benchmark for interpolating its features to the shelf of the surrounding water areas, whose sedimentary cover contains large accumulations of hydrocarbon raw materials. In addition to the stratified section of essentially sedimentary rocks, it is of interest to study igneous formations, which clearly mark tectonic events in the geologic history of the archipelago. In the light of this, the age of these formations remains important. The age of some magmatic complexes of the archipelago is still debatable. This paper focuses upon a lamprophyre complex in the extreme south of Novaya Zemlya, which has been dated at the Late Proterozoic or Late Proterozoic–early Paleozoic(?) until recently. The results obtained for the U–Pb age of apatites contained in the rocks of this complex confirm the Devonian age of the lamprophyres, and it is suggested by estimates based on the presented data that the emplacement time lies in a range from 360 to 398 Ma. This means that they might be associated with riftogenic processes on Novaya Zemlya since the second half of the Early Devonian, when the stage of short-term stable carbonate sedimentation (in the first half of the Devonian Period) was replaced by the initiation of a new structural–formational zonal sequence.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45728800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Novikov, D. Nazarov, M. Mikharevich, A.S. Gladysheva, M. V. Ruchkin, S. G. Prudnikov
—The paper focuses on the surface topography and deposits associated with the Late Pleistocene ice-dammed lake in the valley of the Kharal River dammed by the Azas ice sheet in a depression between the East Sayan and Akademik Obruchev Range. The study includes paleogeographic reconstructions for the time spans before the lake formation and drainage; reconstruction of vegetation in the lake area based on pollen and paleocarpological data; and dating by optically stimulated luminescence (OSL) and 40Ar/39Ar methods. The OSL and Ar–Ar dates provide more rigorous constraints on the history of deposition and topography in the western Serligkhem Basin. The territory was affected by erosion and subsequent basaltic volcanism at 6.9 ± 0.7 and 2.2 ± 0.7 Ma. The erosion valleys were dammed by the edge of an ice sheet and then by its moraine, which produced large Upper Kharal damlake. According to OSL data, the lake existed between 36 ± 4 and 14 ± 3 ka BP. The related glacial, glaciolimnic, and glaciofluvial facies in the area were deposited at the end of the Late Pleistocene (stages III and IV of regional stratigraphy).
-本文重点研究了位于东萨扬山脉和奥布鲁切夫山脉之间的洼地上，由阿扎斯冰盖筑坝的喀拉拉河流域的晚更新世冰坝湖的地表地形和沉积物。研究包括湖泊形成和排水前的古地理重建;基于花粉和古考古资料的湖区植被重建光学激发发光法(OSL)和40Ar/39Ar测年法。OSL和Ar-Ar日期对Serligkhem盆地西部的沉积和地形历史提供了更严格的限制。该地区在6.9±0.7 Ma和2.2±0.7 Ma受到侵蚀和随后的玄武岩火山作用的影响。受侵蚀的山谷被冰原的边缘筑坝，然后被冰原的冰碛所阻塞，形成了巨大的上喀拉尔湖。根据OSL资料，该湖存在于36±4 ~ 14±3 ka BP之间。该区相关的冰川相、冰湖相和冰河相沉积于晚更新世末期(区域地层学的第三和第四阶段)。
{"title":"The Azas Ice Sheet and Its Role in the Formation of Late Pleistocene Ice-Dammed Lakes in Southern Siberia: Case Study of Upper Kharal Paleolake","authors":"I. Novikov, D. Nazarov, M. Mikharevich, A.S. Gladysheva, M. V. Ruchkin, S. G. Prudnikov","doi":"10.2113/rgg20224494","DOIUrl":"https://doi.org/10.2113/rgg20224494","url":null,"abstract":"\u0000 —The paper focuses on the surface topography and deposits associated with the Late Pleistocene ice-dammed lake in the valley of the Kharal River dammed by the Azas ice sheet in a depression between the East Sayan and Akademik Obruchev Range. The study includes paleogeographic reconstructions for the time spans before the lake formation and drainage; reconstruction of vegetation in the lake area based on pollen and paleocarpological data; and dating by optically stimulated luminescence (OSL) and 40Ar/39Ar methods. The OSL and Ar–Ar dates provide more rigorous constraints on the history of deposition and topography in the western Serligkhem Basin. The territory was affected by erosion and subsequent basaltic volcanism at 6.9 ± 0.7 and 2.2 ± 0.7 Ma. The erosion valleys were dammed by the edge of an ice sheet and then by its moraine, which produced large Upper Kharal damlake. According to OSL data, the lake existed between 36 ± 4 and 14 ± 3 ka BP. The related glacial, glaciolimnic, and glaciofluvial facies in the area were deposited at the end of the Late Pleistocene (stages III and IV of regional stratigraphy).","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47482928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Gusev, Ya.D. Yarzhembovsky, A. Makariev, A. Molodkov, F. Maksimov, N. V. Kupriyanova, N. A. Kostromina, O. Rudenko, A. Krylov, V. Sharin, A. Sharapova
—The rarely visited islands of the Kara Sea in its Prytaimyr zone have been studied during a geological survey on the scale 1:1,000,000. The Quaternary deposits of the islands are represented by the Middle Paleo-Pleistocene to Holocene marine, lacustrine-marsh, alluvial and slope sediments. New radiocarbon and uranium-thorium dating has been obtained for the Quaternary sediments, using organic remains (wood, peat, mollusk shells). For the first time, dating on sandy sediments was obtained for the islands, using the method of infrared optically stimulated luminescence (IR-OSL). The sediments of marine terraces are of the greatest distribution on the islands; these sediments can be correlated with the Karginsky (MIS 3) horizon, lacustrine-marsh sediments and deposits of the cover complex, containing flora remains, mainly the Holocene.
-在一项规模为1:10万的地质调查中，研究了喀拉海Prytaimyr地区很少有人参观的岛屿。岛上的第四纪沉积以中古更新世至全新世海相、湖沼沉积、冲积沉积和斜坡沉积为代表。利用有机残留物(木材、泥炭、软体动物壳)对第四纪沉积物进行了新的放射性碳和铀钍定年。首次利用红外光激发发光(IR-OSL)方法对沙质沉积物进行了测年。海相阶地沉积物在岛屿上分布最广;这些沉积物可以与Karginsky (MIS 3)层位、湖沼沉积物和覆盖复合体沉积物相对应，其中包含植物遗迹，主要是全新世。
{"title":"Quaternary Deposits of the Pritaymyr Islands (the Kara Shelf)","authors":"E. Gusev, Ya.D. Yarzhembovsky, A. Makariev, A. Molodkov, F. Maksimov, N. V. Kupriyanova, N. A. Kostromina, O. Rudenko, A. Krylov, V. Sharin, A. Sharapova","doi":"10.2113/rgg20224510","DOIUrl":"https://doi.org/10.2113/rgg20224510","url":null,"abstract":"\u0000 —The rarely visited islands of the Kara Sea in its Prytaimyr zone have been studied during a geological survey on the scale 1:1,000,000. The Quaternary deposits of the islands are represented by the Middle Paleo-Pleistocene to Holocene marine, lacustrine-marsh, alluvial and slope sediments. New radiocarbon and uranium-thorium dating has been obtained for the Quaternary sediments, using organic remains (wood, peat, mollusk shells). For the first time, dating on sandy sediments was obtained for the islands, using the method of infrared optically stimulated luminescence (IR-OSL). The sediments of marine terraces are of the greatest distribution on the islands; these sediments can be correlated with the Karginsky (MIS 3) horizon, lacustrine-marsh sediments and deposits of the cover complex, containing flora remains, mainly the Holocene.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47430462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
—We report results of an integrated interpretation of geophysical data (2D CDP seismic acquisition and gravity and magnetic survey) conducted by Gazpromneft Science and Technology Center in the North Wrangel lease block on the East Siberian Sea shelf. The newly obtained geophysical data have allowed us to update the geological model of the sedimentary cover within the North Wrangel lease block, to clarify the limits of the Drem-Khed Trough, to reconstruct the conditions under which sedimentary complexes formed, and to identify possible promising oil and gas accumulation zones. We were able to determine the position of the main stratigraphic unconformities, to propose several approaches to their interpretation, and to identify the clinoform architecture of the Aptian–Albian and Cenozoic complexes within the Drem-Khed Trough. The integrated review of geological and geophysical data has been helpful in refining the framework of the main structures adjoining the trough and predicting the extent of potential reservoirs and oil and gas source rocks throughout the sedimentary cover. The Upper Cretaceous and Cenozoic complexes are regarded as oil and gas exploration targets.
{"title":"Newly Acquired Data on the Geologic Structure and Hydrocarbon Potential in the Eastern Part of the East Siberian Sea Shelf","authors":"G. Zavarzina, D. S. Shapabaeva, O. Zakharova","doi":"10.2113/rgg20234522","DOIUrl":"https://doi.org/10.2113/rgg20234522","url":null,"abstract":"\u0000 —We report results of an integrated interpretation of geophysical data (2D CDP seismic acquisition and gravity and magnetic survey) conducted by Gazpromneft Science and Technology Center in the North Wrangel lease block on the East Siberian Sea shelf. The newly obtained geophysical data have allowed us to update the geological model of the sedimentary cover within the North Wrangel lease block, to clarify the limits of the Drem-Khed Trough, to reconstruct the conditions under which sedimentary complexes formed, and to identify possible promising oil and gas accumulation zones. We were able to determine the position of the main stratigraphic unconformities, to propose several approaches to their interpretation, and to identify the clinoform architecture of the Aptian–Albian and Cenozoic complexes within the Drem-Khed Trough. The integrated review of geological and geophysical data has been helpful in refining the framework of the main structures adjoining the trough and predicting the extent of potential reservoirs and oil and gas source rocks throughout the sedimentary cover. The Upper Cretaceous and Cenozoic complexes are regarded as oil and gas exploration targets.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41533902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
—Magnetic and density depth models were calculated for the Malmyzh, Pony-Muli, and Anadzhakan porphyry-copper ore clusters emplaced in the northern part of the Middle Amur sedimentary basin. Based on analysis of anomalous magnetic field (magnetic model) data, a magmatogenic ring structure determining spatial patterns in localization of porphyry-copper mineralization in the Malmyzh and Pony-Muli ore clusters was established. It is shown that similar structures in the anomalous magnetic field are reported for many porphyry copper deposits. The area of the identified geologic structure can be considered as a high-potential region for detection of goldcopper-porphyry ore mineralization. Within the ring structure, perspective areas containing granitoid and diorite intrusions developed along its periphery and seated beneath the Middle Amur basin sedimentary cover can also be identified. Geophysical depth models are calculated for individual ore clusters with Au–Cu porphyry mineralization, to determine subsurface lithology and structures that may be useful for assessing regional ore potential and deducing areas for metallogenic exploration. The geophysical data-based deep subsurface model for the Malmyzh ore cluster is found to be consistent with the integrated petrological models developed by Richards and Sillitoe for giant Cuporphyry deposits.
{"title":"Further Insights into Deep Structure of Malmyzh, Pony-Muli, and Anadzhakan Ore Clusters in the Middle Amur Sedimentary Basin (Northern Sikhote-Alin Orogenic Belt)","authors":"A. Didenko, M. Nosyrev, G. Z. Gil’manova","doi":"10.2113/rgg20224515","DOIUrl":"https://doi.org/10.2113/rgg20224515","url":null,"abstract":"\u0000 —Magnetic and density depth models were calculated for the Malmyzh, Pony-Muli, and Anadzhakan porphyry-copper ore clusters emplaced in the northern part of the Middle Amur sedimentary basin. Based on analysis of anomalous magnetic field (magnetic model) data, a magmatogenic ring structure determining spatial patterns in localization of porphyry-copper mineralization in the Malmyzh and Pony-Muli ore clusters was established. It is shown that similar structures in the anomalous magnetic field are reported for many porphyry copper deposits. The area of the identified geologic structure can be considered as a high-potential region for detection of goldcopper-porphyry ore mineralization. Within the ring structure, perspective areas containing granitoid and diorite intrusions developed along its periphery and seated beneath the Middle Amur basin sedimentary cover can also be identified. Geophysical depth models are calculated for individual ore clusters with Au–Cu porphyry mineralization, to determine subsurface lithology and structures that may be useful for assessing regional ore potential and deducing areas for metallogenic exploration. The geophysical data-based deep subsurface model for the Malmyzh ore cluster is found to be consistent with the integrated petrological models developed by Richards and Sillitoe for giant Cuporphyry deposits.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44726152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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