Pub Date : 2024-03-18DOI: 10.1134/s1028334x2460110x
V. I. Karev, Yu. F. Kovalenko
Abstract
Rock specimens of the reservoir’s core material from the Chayanda oil and gas condensate field (OGCF) were tested using the Triaxial Independent Load Test System of the Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences (TILTS) in order to experimentally study the effect exerted by desalinization of reservoir rocks on their strain, strength, and filtration characteristics. According to the study data, desalinization considerably increases a rock permeability. Strain and strength properties of the studied rocks change toward softening (except for an internal friction angle), nevertheless remaining relatively high. Based on the experimental physical modeling of the pressure reducing process at the bottom of a horizontal well using TILTS, a slight decrease in elastic and strength properties of the Chayanda OGCF reservoir rocks after their desalinization should not affect the stability of the well’s walls. The results obtained make it possible to draw the important practical conclusion: when operating the field at the stage of salt washing out due to water filtration under the operation process, a dramatic increase in the risks related to reservoir destruction and higher sand production should not be expected.
摘要 俄罗斯科学院伊什林斯基力学问题研究所（TILTS）的三轴独立载荷试验系统对恰扬达油气凝析气田（OGCF）的储层岩心材料试样进行了测试，以实验研究储层岩石脱盐对其应变、强度和过滤特性的影响。根据研究数据，脱盐大大增加了岩石的渗透性。所研究岩石的应变和强度特性向软化方向变化（内摩擦角除外），但仍保持相对较高的水平。根据使用 TILTS 对水平井底部减压过程进行的实验物理建模，恰扬达 OGCF 储层岩石在脱盐后弹性和强度特性的轻微下降不会影响井壁的稳定性。根据所获得的结果，我们可以得出一个重要的实用结论：当油田在运行过程中由于水过滤而导致盐分被冲洗掉时，预计与储层破坏和产砂量增加有关的风险不会急剧增加。
{"title":"The Influence of Desalinization of Reservoir Rocks on Their Mechanical and Filtration Properties by Example of the Chayanda Field","authors":"V. I. Karev, Yu. F. Kovalenko","doi":"10.1134/s1028334x2460110x","DOIUrl":"https://doi.org/10.1134/s1028334x2460110x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Rock specimens of the reservoir’s core material from the Chayanda oil and gas condensate field (OGCF) were tested using the Triaxial Independent Load Test System of the Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences (TILTS) in order to experimentally study the effect exerted by desalinization of reservoir rocks on their strain, strength, and filtration characteristics. According to the study data, desalinization considerably increases a rock permeability. Strain and strength properties of the studied rocks change toward softening (except for an internal friction angle), nevertheless remaining relatively high. Based on the experimental physical modeling of the pressure reducing process at the bottom of a horizontal well using TILTS, a slight decrease in elastic and strength properties of the Chayanda OGCF reservoir rocks after their desalinization should not affect the stability of the well’s walls. The results obtained make it possible to draw the important practical conclusion: when operating the field at the stage of salt washing out due to water filtration under the operation process, a dramatic increase in the risks related to reservoir destruction and higher sand production should not be expected.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165438","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}
Pub Date : 2024-03-18DOI: 10.1134/s1028334x2360322x
Yucheng Su, Shuai Fu, Boyang Jiao, Yekang Su, Taoning Mao, Yuping He, Yi Jiang
Abstract
In this work, we used the convolutional neural network (CNN) method to invert sea surface height (SSH) from the Global Navigation Satellite System (GNSS) delayed Doppler map (DDM) data during 2009–2017 and compared the CNN inversion data with those obtained from traditional simple random forest (RF) method. SSH observations from the OSTM/Jason-2 satellite were used to judge the merits of the two methods. The results show that both methods yield good SSH inversion results, but when the training set is 9000, the root mean square errors of the SSH inversion results based on the CNN and the RF method are 16.78 and 15.96 respectively; as the training set increases above 9000, the accuracy of the CNN method is significantly better than that of the RF method. This suggests that SSH inversion based on the CNN method will become more advantageous as more data become available.
{"title":"Application of Deep Learning in Sea Surface Height Estimation of GNSS Data Sets","authors":"Yucheng Su, Shuai Fu, Boyang Jiao, Yekang Su, Taoning Mao, Yuping He, Yi Jiang","doi":"10.1134/s1028334x2360322x","DOIUrl":"https://doi.org/10.1134/s1028334x2360322x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this work, we used the convolutional neural network (CNN) method to invert sea surface height (SSH) from the Global Navigation Satellite System (GNSS) delayed Doppler map (DDM) data during 2009–2017 and compared the CNN inversion data with those obtained from traditional simple random forest (RF) method. SSH observations from the OSTM/Jason-2 satellite were used to judge the merits of the two methods. The results show that both methods yield good SSH inversion results, but when the training set is 9000, the root mean square errors of the SSH inversion results based on the CNN and the RF method are 16.78 and 15.96 respectively; as the training set increases above 9000, the accuracy of the CNN method is significantly better than that of the RF method. This suggests that SSH inversion based on the CNN method will become more advantageous as more data become available.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165412","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}
Pub Date : 2024-03-18DOI: 10.1134/s1028334x2460097x
P. S. Belyanin, N. I. Belyanina
Abstract
The high-resolution pollen record retrieved from dated sediments of the Khanka Depression has made it possible for the first time to reconstruct evolution of vegetation in the south of the Russian Far East that occurred during one of the coldest phase of MIS 2 – the Younger Dryas. The results of the spore-pollen analysis have shown that worsening of climate conditions between 18 200 and 15 500 cal yr BP that occurred after the first, slight warming during MIS 2, caused boreal flora plants, dominating in the south of Russian Far East, to spread again in the drier and colder climate comparable to the Gydan Stage of the Sartan Glaciation. Their distribution areas in the cold climate that differed significantly from the modern ones again started to shift to the south due to increasing cooling. The spruce and small-leaved forests, sparse larch and dwarf birch, alder and dwarf pine forests, and also sphagnum bogs dominated in the ecosystems of the region.
{"title":"The First Pollen Record of the Younger Dryas in the South of the Russian Far East","authors":"P. S. Belyanin, N. I. Belyanina","doi":"10.1134/s1028334x2460097x","DOIUrl":"https://doi.org/10.1134/s1028334x2460097x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The high-resolution pollen record retrieved from dated sediments of the Khanka Depression has made it possible for the first time to reconstruct evolution of vegetation in the south of the Russian Far East that occurred during one of the coldest phase of MIS 2 – the Younger Dryas. The results of the spore-pollen analysis have shown that worsening of climate conditions between 18 200 and 15 500 cal yr BP that occurred after the first, slight warming during MIS 2, caused boreal flora plants, dominating in the south of Russian Far East, to spread again in the drier and colder climate comparable to the Gydan Stage of the Sartan Glaciation. Their distribution areas in the cold climate that differed significantly from the modern ones again started to shift to the south due to increasing cooling. The spruce and small-leaved forests, sparse larch and dwarf birch, alder and dwarf pine forests, and also sphagnum bogs dominated in the ecosystems of the region.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165451","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}
Pub Date : 2024-03-18DOI: 10.1134/s1028334x24601147
Abstract
Dating of igneous rocks from paleo-island arc complexes of orogenic belts makes it possible to determine the precise timing of subduction processes that occurred during the formation of the orogen. Within the central (East Transbaikal) part of the Mongol–Okhotsk orogenic belt, the Kamenka island-arc terrane is an example of such a complex. Its intrusive part is included into the Bereya complex, represented by a gabbro-diorite-tonalite-plagiogranite series of rocks demonstrating subduction geochemical characteristics. The dating of zircons from acidic rocks of this complex by the U–Pb classical method showed that they were formed in a narrow time interval of 203 ± 1–205 ± 1 Ma, which corresponds to the Norian–Rhaetian boundary of the Late Triassic. Taking into account the previously obtained age of the diorites (254 ± 5 Ma), the timing of formation of the entire series of the intrusive rocks is about 50 Ma, thus indicating the probable subduction along the northern (in modern coordinates) margin of the Mongol–Okhotsk Paleocean under the Siberian paleocontinent in the Late Permian – Late Triassic. The diorites of the first phase have positive values of εND(254 Ma) = 3.2–3.6 (TNd(DM) = 879–994 Ma), and the plagiogranites have ɛND(205 Ma) = 2.3–3.5 (TNd(DM) = 859–1028 Ma), which points to the relationship between these rocks and the substance of the depleted mantle source and is consistent with the Sm–Nd isotope characteristics of the juvenile crust of the Central Asian orogenic belt.
{"title":"Age and Origin of the Bereya Complex Granitoids from the Kamenka Terrane of the Mongol–Okhotsk Orogenic Belt: Results of U–Pb (ID-TIMS) Geochronological and Sm–Nd Isotope-Geochemical Studies","authors":"","doi":"10.1134/s1028334x24601147","DOIUrl":"https://doi.org/10.1134/s1028334x24601147","url":null,"abstract":"<span> <h3>Abstract</h3> <p>Dating of igneous rocks from paleo-island arc complexes of orogenic belts makes it possible to determine the precise timing of subduction processes that occurred during the formation of the orogen. Within the central (East Transbaikal) part of the Mongol–Okhotsk orogenic belt, the Kamenka island-arc terrane is an example of such a complex. Its intrusive part is included into the Bereya complex, represented by a gabbro-diorite-tonalite-plagiogranite series of rocks demonstrating subduction geochemical characteristics. The dating of zircons from acidic rocks of this complex by the U–Pb classical method showed that they were formed in a narrow time interval of 203 ± 1–205 ± 1 Ma, which corresponds to the Norian–Rhaetian boundary of the Late Triassic. Taking into account the previously obtained age of the diorites (254 ± 5 Ma), the timing of formation of the entire series of the intrusive rocks is about 50 Ma, thus indicating the probable subduction along the northern (in modern coordinates) margin of the Mongol–Okhotsk Paleocean under the Siberian paleocontinent in the Late Permian – Late Triassic. The diorites of the first phase have positive values of ε<sub>ND(254 Ma)</sub> = 3.2–3.6 (<em>T</em><sub>Nd(DM)</sub> = 879–994 Ma), and the plagiogranites have ɛ<sub>ND(205 Ma)</sub> = 2.3–3.5 (<em>T</em><sub>Nd(DM)</sub> = 859–1028 Ma), which points to the relationship between these rocks and the substance of the depleted mantle source and is consistent with the Sm–Nd isotope characteristics of the juvenile crust of the Central Asian orogenic belt.</p> </span>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166020","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}
Pub Date : 2024-03-18DOI: 10.1134/s1028334x24601111
K. S. Ivanov, N. V. Vakhrusheva, V. N. Puchkov, P. B. Shiryaev, N. N. Farrakhova, A. E. Bogomolova
Abstract
Composition and age of unserpentinized harzburgites found as boudins and relict bodies in the Voikar–Synya massif in the olivine–antigorite fields have been studied. Rock and mineral structure and composition, as well as REE distribution and Sm–Nd absolute dating (≈2330 Ma) make it possible to consider these unserpentinized harzburgites as mantle fragments and the earliest ultramafic rocks of the Voikar–Synya massif. Silicates of these harzburgites are characterized by higher chromium which turns into chrome spinellide in different subsequent processes. Based on the data obtained, the resources of chromium mobilized during the transformation of primary ultramafic rocks have been evaluated.
{"title":"Unserpentinized Harzburgites of the Voikar–Synya Massif in the Polar Urals as the Initial Chromium Source for the Deposit Formation","authors":"K. S. Ivanov, N. V. Vakhrusheva, V. N. Puchkov, P. B. Shiryaev, N. N. Farrakhova, A. E. Bogomolova","doi":"10.1134/s1028334x24601111","DOIUrl":"https://doi.org/10.1134/s1028334x24601111","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Composition and age of unserpentinized harzburgites found as boudins and relict bodies in the Voikar–Synya massif in the olivine–antigorite fields have been studied. Rock and mineral structure and composition, as well as REE distribution and Sm–Nd absolute dating (≈2330 Ma) make it possible to consider these unserpentinized harzburgites as mantle fragments and the earliest ultramafic rocks of the Voikar–Synya massif. Silicates of these harzburgites are characterized by higher chromium which turns into chrome spinellide in different subsequent processes. Based on the data obtained, the resources of chromium mobilized during the transformation of primary ultramafic rocks have been evaluated.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165417","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}
Pub Date : 2024-03-18DOI: 10.1134/s1028334x24601068
K. G. Sukhanova, A. B. Kuznetsov, S. G. Skublov
Abstract
The work reports on the results of the mineralogical and petrographic study of the Borodino meteorite (H5). For the first time, meteorite minerals were described and their chemical compositions were given. The following were found in the Borodino meteorite: olivine (Fa 18.16 ± 1.15), Ca-poor pyroxene – (clino)enstatite (En 81.37 ± 1.73, Wo 1.18 ± 0.31), Ca-rich pyroxene – augite (En 57.23 ± 1.57, Wo 39.38 ± 2.68), diopside (En 51, Wo 45), pigeonite (En 69, Wo 6), plagioclases – oligoclase (An 12.16 ± 1.24, Or 5.68 ± 2.12), andesine (An 48.23 ± 1.84, Or 1.23 ± 0.12), anorthoclase (An 0, Or 36) and sanidine (An 0, Or 40.00 ± 1.1), and poorly crystallized glasses of the feldspathic composition, merrillite and chromespinelide. The obtained data made it possible to estimate a degree of terrestrial weathering of the meteorite as W0 and the stage of impact metamorphism (S1-2), which suggests good preservation of the meteorite material. The composition of olivine and Cr-spinel, determined by the Electron Probe Microanalysis, was used to estimate the peak temperature of thermal metamorphism at 720°C, which falls within the temperature range (670–740°C) typical of chondrites of a petrological type 5. The presence of Ca-rich pyroxenes, large grains of Ca–Na–Mg phosphates and chromite-pigeonite aggregates in the meteorite matrix indicate the prolonged heating of the material.
{"title":"The Borodino Meteorite: Evolution on the Parent Body","authors":"K. G. Sukhanova, A. B. Kuznetsov, S. G. Skublov","doi":"10.1134/s1028334x24601068","DOIUrl":"https://doi.org/10.1134/s1028334x24601068","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The work reports on the results of the mineralogical and petrographic study of the Borodino meteorite (H5). For the first time, meteorite minerals were described and their chemical compositions were given. The following were found in the Borodino meteorite: olivine (Fa 18.16 ± 1.15), Ca-poor pyroxene – (clino)enstatite (En 81.37 ± 1.73, Wo 1.18 ± 0.31), Ca-rich pyroxene – augite (En 57.23 ± 1.57, Wo 39.38 ± 2.68), diopside (En 51, Wo 45), pigeonite (En 69, Wo 6), plagioclases – oligoclase (An 12.16 ± 1.24, Or 5.68 ± 2.12), andesine (An 48.23 ± 1.84, Or 1.23 ± 0.12), anorthoclase (An 0, Or 36) and sanidine (An 0, Or 40.00 ± 1.1), and poorly crystallized glasses of the feldspathic composition, merrillite and chromespinelide. The obtained data made it possible to estimate a degree of terrestrial weathering of the meteorite as W0 and the stage of impact metamorphism (S1-2), which suggests good preservation of the meteorite material. The composition of olivine and Cr-spinel, determined by the Electron Probe Microanalysis, was used to estimate the peak temperature of thermal metamorphism at 720°C, which falls within the temperature range (670–740°C) typical of chondrites of a petrological type 5. The presence of Ca-rich pyroxenes, large grains of Ca–Na–Mg phosphates and chromite-pigeonite aggregates in the meteorite matrix indicate the prolonged heating of the material.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165534","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}
Pub Date : 2024-03-18DOI: 10.1134/s1028334x2460107x
M. A. Rogov, V. A. Marinov, E. Yu. Baraboshkin, A. E. Igol’nikov, M. Košťák
Abstract
Ammonites of the subfamily Collignoniceratinae have been found in the Turonian Stage of Western Siberia. These findings have made it possible to substantiate the Collignoniceras woollgari zone in the Middle Turonian of this region, to recognize the ammonite dispersal features in the Arctic region, and to clarify the paleogeography of the Turonian age. Based on the occurrence frequency of Collignoniceras woollgari regulare in the boreholes in the north of Western Siberia, their penetration into the West Siberian basin through the Arctic region from the Western Interior Sea of North America is most likely. Collignoniceratinae has been identified for the first time in the Upper Turonian of the Yangoda River (west of the Yenisei–Khatanga regional trough).
{"title":"Ammonites of the Subfamily Collignoniceratinae in the Turonian Stage (Upper Cretaceous) in Western Siberia and Their Implications for Stratigraphy and Paleogeography","authors":"M. A. Rogov, V. A. Marinov, E. Yu. Baraboshkin, A. E. Igol’nikov, M. Košťák","doi":"10.1134/s1028334x2460107x","DOIUrl":"https://doi.org/10.1134/s1028334x2460107x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Ammonites of the subfamily Collignoniceratinae have been found in the Turonian Stage of Western Siberia. These findings have made it possible to substantiate the <i>Collignoniceras woollgari</i> zone in the Middle Turonian of this region, to recognize the ammonite dispersal features in the Arctic region, and to clarify the paleogeography of the Turonian age. Based on the occurrence frequency of <i>Collignoniceras woollgari regulare</i> in the boreholes in the north of Western Siberia, their penetration into the West Siberian basin through the Arctic region from the Western Interior Sea of North America is most likely. Collignoniceratinae has been identified for the first time in the Upper Turonian of the Yangoda River (west of the Yenisei–Khatanga regional trough).</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140165536","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}
Pub Date : 2024-03-08DOI: 10.1134/s1028334x24601007
T. O. Chaplina, A. V. Kistovich, V. P. Pachnenko
Abstract
The results of experimental and theoretical investigations of hydrocarbon spills on the ice cover are presented based on the laws of conservation of mass and the total energy of the system. Under this model, an approximate equation describing the dynamics of the area of spreading in time is obtained. Comparison of theoretical and experimental results shows good agreement.
{"title":"Axisymmetric Spreading of Petroleum Products on the Ice Cover","authors":"T. O. Chaplina, A. V. Kistovich, V. P. Pachnenko","doi":"10.1134/s1028334x24601007","DOIUrl":"https://doi.org/10.1134/s1028334x24601007","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of experimental and theoretical investigations of hydrocarbon spills on the ice cover are presented based on the laws of conservation of mass and the total energy of the system. Under this model, an approximate equation describing the dynamics of the area of spreading in time is obtained. Comparison of theoretical and experimental results shows good agreement.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140075403","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}
Pub Date : 2024-03-08DOI: 10.1134/s1028334x24601044
D. V. Alexeiev, A. K. Khudoley, S. A. DuFrane, A. V. Kushnareva, N. V. Bryanskiy, A. A. Karimov
Abstract
Detrital zircon dating allows us to elucidate the age and provenance of siliciclastic strata of the Sarydjaz and Ichkebash formations in the Middle Tianshan of eastern Kyrgyzstan, previously thought to be of the Middle or Late Ordovician age. New data indicate that the upper part of the Ichkebash Formation contains Lower Silurian sediments, previously unknown in this region. The Kanachu Formation, which lies stratigraphically above, is also not older than the Silurian in age. The absence of marine fauna at these levels apparently reflects the predominant development of deltaic facies. The paleocurrent indicators and the ages of detrital zircons point to its provenance in the North Tianshan (NTSh). Grains with ages from the Late Cambrian to the Silurian, synchronous with the main stage of the Early Paleozoic magmatism in the NTSh, predominate in the Ichkebash Formation. The occurrence of Precambrian detrital zircons in all dated samples and especially in the Sarydjaz Formation indicates the erosion of Precambrian rocks. The provenance most likely located in the Chu-Kendyktas Massif, where the Precambrian detrital zircons in the Neoproterozoic and Early Paleozoic metasedimentary rocks demonstrate a similar distribution of the ages. The foredeep in the Middle Tianshan was formed in the Late Ordovician and Early Silurian generally subsynchronously with the main orogenic event in the NTSh.
{"title":"Ordovician and Silurian Siliciclastic Strata of the Middle Tianshan (Eastern Kyrgyzstan): Age and Provenance According to Detrital Zircon Dating","authors":"D. V. Alexeiev, A. K. Khudoley, S. A. DuFrane, A. V. Kushnareva, N. V. Bryanskiy, A. A. Karimov","doi":"10.1134/s1028334x24601044","DOIUrl":"https://doi.org/10.1134/s1028334x24601044","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Detrital zircon dating allows us to elucidate the age and provenance of siliciclastic strata of the Sarydjaz and Ichkebash formations in the Middle Tianshan of eastern Kyrgyzstan, previously thought to be of the Middle or Late Ordovician age. New data indicate that the upper part of the Ichkebash Formation contains Lower Silurian sediments, previously unknown in this region. The Kanachu Formation, which lies stratigraphically above, is also not older than the Silurian in age. The absence of marine fauna at these levels apparently reflects the predominant development of deltaic facies. The paleocurrent indicators and the ages of detrital zircons point to its provenance in the North Tianshan (NTSh). Grains with ages from the Late Cambrian to the Silurian, synchronous with the main stage of the Early Paleozoic magmatism in the NTSh, predominate in the Ichkebash Formation. The occurrence of Precambrian detrital zircons in all dated samples and especially in the Sarydjaz Formation indicates the erosion of Precambrian rocks. The provenance most likely located in the Chu-Kendyktas Massif, where the Precambrian detrital zircons in the Neoproterozoic and Early Paleozoic metasedimentary rocks demonstrate a similar distribution of the ages. The foredeep in the Middle Tianshan was formed in the Late Ordovician and Early Silurian generally subsynchronously with the main orogenic event in the NTSh.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140075367","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}
Pub Date : 2024-03-08DOI: 10.1134/s1028334x24600981
Z. I. Slukovskii, A. V. Guzeva
Abstract
Primary studies of the concentrations of rare elements in the sediments of two lakes on King George Island (Kitezh and Glubokoe) showed that their geochemistry reflects the geological features of the area. Compared to the composition of the upper part of the Earth’s crust, the studied sediments are enriched in Cu, Cd, V, Tl, Mn, Ti, and P. Similar patterns have been identified in the geochemistry of volcanic and sedimentary rocks of the Fildes Peninsula. Trends in REE changes generally follow their behavior in rocks, but the overall REE concentration in sediments of lakes is higher, which may be due to the presence of organic matter accumulating in sediments of water bodies. Unlike the aquatic environment, the chemical composition of sediments does not reflect the significant influence of the activities of polar stations. However, small increases in Pb and Sb concentrations in the upper sediments suggest the influence of long–range atmospheric transport of the contaminants.
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