Pub Date : 2025-11-01DOI: 10.1016/j.geogeo.2024.100345
Irina Sotnikova , Anna Spivak , Alla Viryus , Michael Kuzmin , Egor Zakharchenko , Tatiana Kolotilina , Natalia Alymova
The typomorphic features and ages of monazites from two zones of ore-bearing pegmatites of the Burpala massif (Western and Britolite) were studied. This made it possible to clarify the stages of formation of the vein phase of the intrusive rocks. Information on the relationship of monazites with rock-forming and ore minerals was also obtained. Using the CHIME method, the isochronous Th-U-Pb age of monazites from rare-metal pegmatites was calculated: 287 ± 54 Ma (Western zone) and 273 ± 69 Ma (Britholite zone). The obtained age values for the rare-metal pegmatites of the Burpala massif are in good agreement with the available geological and geochronological information and indicate the existence of several stages of their formation, which allows us to supplement the magmatism scheme of the vein complex (mariupolites → foyaites → rare-metal pegmatites of the Western zone → rare-metal pegmatites of the Britholite zone → apatite-fluorite rocks → carbonatites→ alaskites and alkaline granites). The obtained age for monazites from two zones of pegmatites is close by time of formation to the pulaskites of the main phase and rare-metal pegmatites of the North-Western zone of the Burpala massif and belongs to the general Late Paleozoic stage of intraplate magmatism in the northern framing of the Angara-Vitim batholith.
{"title":"Stage of the vein series formation processes of the Burpala massif (North Baikal), according to chemical microprobe Th-U-Pb dating of monazites","authors":"Irina Sotnikova , Anna Spivak , Alla Viryus , Michael Kuzmin , Egor Zakharchenko , Tatiana Kolotilina , Natalia Alymova","doi":"10.1016/j.geogeo.2024.100345","DOIUrl":"10.1016/j.geogeo.2024.100345","url":null,"abstract":"<div><div>The typomorphic features and ages of monazites from two zones of ore-bearing pegmatites of the Burpala massif (Western and Britolite) were studied. This made it possible to clarify the stages of formation of the vein phase of the intrusive rocks. Information on the relationship of monazites with rock-forming and ore minerals was also obtained. Using the CHIME method, the isochronous Th-U-Pb age of monazites from rare-metal pegmatites was calculated: 287 ± 54 Ma (Western zone) and 273 ± 69 Ma (Britholite zone). The obtained age values for the rare-metal pegmatites of the Burpala massif are in good agreement with the available geological and geochronological information and indicate the existence of several stages of their formation, which allows us to supplement the magmatism scheme of the vein complex (mariupolites → foyaites → rare-metal pegmatites of the Western zone → rare-metal pegmatites of the Britholite zone → apatite-fluorite rocks → carbonatites→ alaskites and alkaline granites). The obtained age for monazites from two zones of pegmatites is close by time of formation to the pulaskites of the main phase and rare-metal pegmatites of the North-Western zone of the Burpala massif and belongs to the general Late Paleozoic stage of intraplate magmatism in the northern framing of the Angara-Vitim batholith.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100345"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.geogeo.2025.100388
Igor V. Ashchepkov , N.V. Chalapathi Rao , Rohit Pandey , Sergei V. Rasskazov
{"title":"Geochemistry and petrology of deep seated mantle magmas and their mantle xenoliths and xenocrysts: Applications to the structure and compositions of mantle lithosphere","authors":"Igor V. Ashchepkov , N.V. Chalapathi Rao , Rohit Pandey , Sergei V. Rasskazov","doi":"10.1016/j.geogeo.2025.100388","DOIUrl":"10.1016/j.geogeo.2025.100388","url":null,"abstract":"","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100388"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.geogeo.2025.100383
M. Lachhana Dora , Hassan M. Helmy , Rajkumar Meshram , Nathala K. Rao , Mohamad Shareef , Raghuram , Vivek P. Malviya , Tushar Meshram , Srinivas Rao Baswani , Mohammad Atif Raza , Kirtikumar Randive
This study presents the first identification of an Alaskan-type intrusion within the late-Proterozoic Padhar mafic-ultramafic complex (PMUC), situated along the Central Indian Tectonic Zone (CITZ). The intrusion exhibits a differentiated composition, including peridotite, pyroxenites, hornblende gabbros and diorite. We adopt an integrated approach that combines field studies with analyses of major oxides, in-situ trace elements, and rare-earth element geochemistry. The field evidences of PMUC displays concentric zoning, with a core of dunite surrounded by wehrlite, olivine clinopyroxenite, clinopyroxenite, hornblende clinopyroxenite, and gabbro akin to Alaskan type intrusions. The primary minerals in the PMUC include olivine (forsterite), pyroxene (Cpx and Opx), amphibole, phlogopite, chromite, and magnetite, while secondary minerals like serpentine, chlorite, and talc are also present. The increase in magnesian number (Mg#) of olivine (70–77), orthopyroxene (53–73), and clinopyroxene (67–88) from mafic to ultramafic units indicates differentiation from a common parent melt. The geochemical signature, including negative Nb and Zr anomalies and positive Rb anomalies, suggests fluid metasomatism from slab sediments. The presence of a hydrous parent magma is inferred from the Mg# of early-formed olivine and high amphibole content. Tectonic discrimination plots of pyroxene and amphibole minerals, combined with in-situ trace element chemistry and bulk rock geochemistry, indicate an arc-related origin. The data suggest fluid-driven subduction zone metasomatism, characteristic of Proterozoic Alaskan-type tectonics within the CITZ. Platinum-group element geochemistry shows a high (Pt + Pd)/(Ir + Ru) ratio, similar to that of intrusive rocks of Alaskan types. Geological and geochemical data further support that the PMUC represents a shallow-level (ca. 17 km) segment of a Proterozoic arc, with minor ultramafic units acting as conduits for arc magma in the Betul Belt.
{"title":"Proterozoic arc magmatism from the Padhar mafic-ultramafics in Betul Belt, Central India Tectonic Zone: Insight from petrography, bulk rock and in-situ trace element geochemistry","authors":"M. Lachhana Dora , Hassan M. Helmy , Rajkumar Meshram , Nathala K. Rao , Mohamad Shareef , Raghuram , Vivek P. Malviya , Tushar Meshram , Srinivas Rao Baswani , Mohammad Atif Raza , Kirtikumar Randive","doi":"10.1016/j.geogeo.2025.100383","DOIUrl":"10.1016/j.geogeo.2025.100383","url":null,"abstract":"<div><div>This study presents the first identification of an Alaskan-type intrusion within the late-Proterozoic Padhar mafic-ultramafic complex (PMUC), situated along the Central Indian Tectonic Zone (CITZ). The intrusion exhibits a differentiated composition, including peridotite, pyroxenites, hornblende gabbros and diorite. We adopt an integrated approach that combines field studies with analyses of major oxides, in-situ trace elements, and rare-earth element geochemistry. The field evidences of PMUC displays concentric zoning, with a core of dunite surrounded by wehrlite, olivine clinopyroxenite, clinopyroxenite, hornblende clinopyroxenite, and gabbro akin to Alaskan type intrusions. The primary minerals in the PMUC include olivine (forsterite), pyroxene (Cpx and Opx), amphibole, phlogopite, chromite, and magnetite, while secondary minerals like serpentine, chlorite, and talc are also present. The increase in magnesian number (Mg#) of olivine (70–77), orthopyroxene (53–73), and clinopyroxene (67–88) from mafic to ultramafic units indicates differentiation from a common parent melt. The geochemical signature, including negative Nb and Zr anomalies and positive Rb anomalies, suggests fluid metasomatism from slab sediments. The presence of a hydrous parent magma is inferred from the Mg# of early-formed olivine and high amphibole content. Tectonic discrimination plots of pyroxene and amphibole minerals, combined with <em>in-situ</em> trace element chemistry and bulk rock geochemistry, indicate an arc-related origin. The data suggest fluid-driven subduction zone metasomatism, characteristic of Proterozoic Alaskan-type tectonics within the CITZ. Platinum-group element geochemistry shows a high (Pt + Pd)/(Ir + Ru) ratio, similar to that of intrusive rocks of Alaskan types. Geological and geochemical data further support that the PMUC represents a shallow-level (ca. 17 km) segment of a Proterozoic arc, with minor ultramafic units acting as conduits for arc magma in the Betul Belt.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100383"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.geogeo.2025.100358
Tatyana A. Yasnygina , Sergei V. Rasskazov , Irina S. Chuvashova , Elena V. Saranina
The Ichara Complex of small intrusions is located on the Late Cenozoic Orlov volcanic field of West Sakhalin, in the area of Lamanon Cape. Andesites and dacites of the Ichara Complex and Orlov volcanic field show adakite-like signature (high Sr/Y, low HREE and Y, and high La/Yb) that is associated with magma generation at a crust-mantle transition. Trace element partial melting modelling shows that sources of the adakite-like rocks are the primitive mantle with admixtures of lower crustal (7–12 %) and minor fluid (0.5–1 %) components. Garnet and amphibole contents as well as the degree of partial melting in model sources increase from the older adakite-like andesites of the Orlov volcanic field to the younger andesites and dacites of Ichara Complex. Decreasing 87Sr/86Sr and increasing Sr/Y values from adakite-like andesites to dacites of West Sakhalin correspond to an increasing role of lower crustal and supra-subduction fluid components. The most pronounced adakite-like signature is characteristic of dacites derived from a clinopyroxene-amphibole-garnet source with maximal lower crustal addition. No young slab (MORB-type) material is detected in the modeled sources. In contrast to Ichara adakite-like rocks, the modelling of Daisen adakites from Southwest Honshu yields evidence on melting of the upper part of the Philippine Sea slab with significant contribution of the supra-subduction fluid component.
{"title":"Non-subduction Ichara adakite-like rocks from West Sakhalin (Russian Far East) versus supra-subduction Daisen adakites from SW Japan: Insight from trace-element modelling of sources","authors":"Tatyana A. Yasnygina , Sergei V. Rasskazov , Irina S. Chuvashova , Elena V. Saranina","doi":"10.1016/j.geogeo.2025.100358","DOIUrl":"10.1016/j.geogeo.2025.100358","url":null,"abstract":"<div><div>The Ichara Complex of small intrusions is located on the Late Cenozoic Orlov volcanic field of West Sakhalin, in the area of Lamanon Cape. Andesites and dacites of the Ichara Complex and Orlov volcanic field show adakite-like signature (high Sr/Y, low HREE and Y, and high La/Yb) that is associated with magma generation at a crust-mantle transition. Trace element partial melting modelling shows that sources of the adakite-like rocks are the primitive mantle with admixtures of lower crustal (7–12 %) and minor fluid (0.5–1 %) components. Garnet and amphibole contents as well as the degree of partial melting in model sources increase from the older adakite-like andesites of the Orlov volcanic field to the younger andesites and dacites of Ichara Complex. Decreasing <sup>87</sup>Sr/<sup>86</sup>Sr and increasing Sr/Y values from adakite-like andesites to dacites of West Sakhalin correspond to an increasing role of lower crustal and supra-subduction fluid components. The most pronounced adakite-like signature is characteristic of dacites derived from a clinopyroxene-amphibole-garnet source with maximal lower crustal addition. No young slab (MORB-type) material is detected in the modeled sources. In contrast to Ichara adakite-like rocks, the modelling of Daisen adakites from Southwest Honshu yields evidence on melting of the upper part of the Philippine Sea slab with significant contribution of the supra-subduction fluid component.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100358"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-25DOI: 10.1016/j.geogeo.2025.100469
Wenyue Zhou, Yanyun Sun, Wan Zhang, Guotao Yao, Ruohan Wu
Analysis and research of large complex phenomena before and after the devastating earthquake is of great significance to reduce the threat of natural disasters. Understanding the complex structural deformation of the Longmenshan Fault Zone is essential for elucidating crustal deformation and seismic dynamic mechanisms. This paper analyzes the gravity anomaly distribution characteristics in the Wenchuan Earthquake zone, and subsequently applies edge detection method to invert the pre-earthquake gravity anomalies of the Longmenshan region. The fault distribution characteristics in the Longmenshan region and its adjacent areas before the earthquake have been determined. Besides, morphology difference and possible earthquake formation have been analyzed through the Euler deconvolution results of gravity anomaly profile before and after the earthquake. Finally, a 2-D interactive joint inversion was performed based on the existing seismic and gravity data. The subsurface structure was revealed, and the earthquake formation mechanism was discussed by comparing the underground changes before and after the event.
{"title":"Interpretation of gravity-seismic joint inversion and its application in Longmenshan region","authors":"Wenyue Zhou, Yanyun Sun, Wan Zhang, Guotao Yao, Ruohan Wu","doi":"10.1016/j.geogeo.2025.100469","DOIUrl":"10.1016/j.geogeo.2025.100469","url":null,"abstract":"<div><div>Analysis and research of large complex phenomena before and after the devastating earthquake is of great significance to reduce the threat of natural disasters. Understanding the complex structural deformation of the Longmenshan Fault Zone is essential for elucidating crustal deformation and seismic dynamic mechanisms. This paper analyzes the gravity anomaly distribution characteristics in the Wenchuan Earthquake zone, and subsequently applies edge detection method to invert the pre-earthquake gravity anomalies of the Longmenshan region. The fault distribution characteristics in the Longmenshan region and its adjacent areas before the earthquake have been determined. Besides, morphology difference and possible earthquake formation have been analyzed through the Euler deconvolution results of gravity anomaly profile before and after the earthquake. Finally, a 2-D interactive joint inversion was performed based on the existing seismic and gravity data. The subsurface structure was revealed, and the earthquake formation mechanism was discussed by comparing the underground changes before and after the event.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 1","pages":"Article 100469"},"PeriodicalIF":0.0,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-25DOI: 10.1016/j.geogeo.2025.100468
Abdoul Aboubakar , Bertille Ilalie Manefouet Kentsa , Grace Nissia Rodo , Oussena Bébé Nzie , Stella Nome May , Clotaire José Pako Perabi , Merlot Tongnang Kenzo , Thomas Tatietse Tamo
This study highlights the contribution of geo-electricity to the characterization of geological formations in the Ngaoundal area. Electrical mapping using the Schlumberger device was carried out over 29.9 km², with fifty-one vertical electrical soundings (VES) conducted at 700 m intervals across a zone entirely covered by soils developed on a granitic bedrock. Apparent resistivity maps, for depths ranging from AB/2 = 1.5 to 100 m, reveal low, medium, and high resistivity ranges. Ten main types of VES curves (Q, HK, KH, H, KQ, QH, HKH, K, KQH, and QHK) were identified, classified according to depth and resistivity. Integrated analysis of resistivity maps and VES curves shows lateritic soils dominating the surface, sandy-clay soils at intermediate depth, and fractured or sound bedrock at greater depth. Four pseudo-resistivity sections highlight weak (ρ < 350 Ω·m), medium (350 ≤ ρ ≤ 1800 Ω·m), and strong (ρ ≥ 1800 Ω·m) anomalies, corresponding respectively to loose weathered formations (weathered granite, gravelly soils), fractured granites, and sound granites forming the bedrock. The lateritic layer thickness map identifies three classes: low (1.33–2.58 m), medium (2.59–2.84 m), and high (2.85–8.94 m). Comparison with existing water borehole data confirms the consistency of geophysical models. This complementarity between geophysical methods and direct borehole observations reinforces the reliability of the approach and provides a robust framework for geological and hydrogeological interpretation of the subsurface in the Ngaoundal region.
{"title":"Contribution of the geoelectric method to the identification of geological formations in the Ngaoundal locality (Adamawa, Cameroon)","authors":"Abdoul Aboubakar , Bertille Ilalie Manefouet Kentsa , Grace Nissia Rodo , Oussena Bébé Nzie , Stella Nome May , Clotaire José Pako Perabi , Merlot Tongnang Kenzo , Thomas Tatietse Tamo","doi":"10.1016/j.geogeo.2025.100468","DOIUrl":"10.1016/j.geogeo.2025.100468","url":null,"abstract":"<div><div>This study highlights the contribution of geo-electricity to the characterization of geological formations in the Ngaoundal area. Electrical mapping using the Schlumberger device was carried out over 29.9 km², with fifty-one vertical electrical soundings (VES) conducted at 700 m intervals across a zone entirely covered by soils developed on a granitic bedrock. Apparent resistivity maps, for depths ranging from AB/2 = 1.5 to 100 m, reveal low, medium, and high resistivity ranges. Ten main types of VES curves (Q, HK, KH, H, KQ, QH, HKH, K, KQH, and QHK) were identified, classified according to depth and resistivity. Integrated analysis of resistivity maps and VES curves shows lateritic soils dominating the surface, sandy-clay soils at intermediate depth, and fractured or sound bedrock at greater depth. Four pseudo-resistivity sections highlight weak (<em>ρ</em> < 350 Ω·m), medium (350 ≤ <em>ρ</em> ≤ 1800 Ω·m), and strong (<em>ρ</em> ≥ 1800 Ω·m) anomalies, corresponding respectively to loose weathered formations (weathered granite, gravelly soils), fractured granites, and sound granites forming the bedrock. The lateritic layer thickness map identifies three classes: low (1.33–2.58 m), medium (2.59–2.84 m), and high (2.85–8.94 m). Comparison with existing water borehole data confirms the consistency of geophysical models. This complementarity between geophysical methods and direct borehole observations reinforces the reliability of the approach and provides a robust framework for geological and hydrogeological interpretation of the subsurface in the Ngaoundal region.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 1","pages":"Article 100468"},"PeriodicalIF":0.0,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145464839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-18DOI: 10.1016/j.geogeo.2025.100467
Svetlana Yurievna Artamonova
This paper comprehensively discusses data from electrical resistivity tomography, land geomagnetic surveys, radionuclides, and the major-ion chemistry of water flowing at the epicenter of the Crystal peaceful underground nuclear explosion (it was carried out in 1974). The integrity of the seal at the emplacement hole cap was compromised during the explosion, the soils at the epicenter were contaminated by radionuclides. To immobilize these radionuclides cryogenically and prevent migration of radionuclides from the central explosion area (at a depth of 98 meters), the head of the emplacement hole and its surroundings were buried in 1992 with block-rubble stone material composed of pure limestone and dolomite fragments. Additionally, the block-rubble artificial cover was further reinforced in 2006. The artificial cover is revealed to remain unfrozen and waterlogged nowadays. Snowmelt and rainwater are observed to seep through this cover, while air convection within it likely leads to the condensation of atmospheric moisture. The bicarbonate magnesium-calcium waters that originate from the percolation of rain, melted snow, and atmospheric condensate through the cover are enriched with technogenic ions such as SO₄²⁻, Mg²⁺, Ca²⁺, Li⁺, K⁺, and Sr, alongside natural components like Cl⁻, Mg²⁺, Ca²⁺, K⁺, Na⁺, Br, Sr, I, and Li⁺, which are derived from underground natural gas-brine fluids that rise along the open emplacement hole and the damage zone. It is hypothesized that Li⁺ could be a component of the nuclear explosive device. Given the low current activity of radionuclides in water flowing from beneath the artificial cover (measured in Bq/dm³): ³H, 4–12; ⁹⁰Sr, 0.004–0.4, and diminishing levels of ²³⁹,²⁴⁰Pu (<10⁻⁶), the current migration of technogenic radionuclides with water is assessed as insignificant. Therefore, there is no immediate need for additional measures to strengthen or modify the block-rubble artificial cover.
{"title":"Paradox of the Сrystal peaceful underground nuclear explosion site (Yakutia, 1974): Evidence from electrical resistivity tomography and water runoff chemistry","authors":"Svetlana Yurievna Artamonova","doi":"10.1016/j.geogeo.2025.100467","DOIUrl":"10.1016/j.geogeo.2025.100467","url":null,"abstract":"<div><div>This paper comprehensively discusses data from electrical resistivity tomography, land geomagnetic surveys, radionuclides, and the major-ion chemistry of water flowing at the epicenter of the Crystal peaceful underground nuclear explosion (it was carried out in 1974). The integrity of the seal at the emplacement hole cap was compromised during the explosion, the soils at the epicenter were contaminated by radionuclides. To immobilize these radionuclides cryogenically and prevent migration of radionuclides from the central explosion area (at a depth of 98 meters), the head of the emplacement hole and its surroundings were buried in 1992 with block-rubble stone material composed of pure limestone and dolomite fragments. Additionally, the block-rubble artificial cover was further reinforced in 2006. The artificial cover is revealed to remain unfrozen and waterlogged nowadays. Snowmelt and rainwater are observed to seep through this cover, while air convection within it likely leads to the condensation of atmospheric moisture. The bicarbonate magnesium-calcium waters that originate from the percolation of rain, melted snow, and atmospheric condensate through the cover are enriched with technogenic ions such as SO₄²⁻, Mg²⁺, Ca²⁺, Li⁺, K⁺, and Sr, alongside natural components like Cl⁻, Mg²⁺, Ca²⁺, K⁺, Na⁺, Br, Sr, I, and Li⁺, which are derived from underground natural gas-brine fluids that rise along the open emplacement hole and the damage zone. It is hypothesized that Li⁺ could be a component of the nuclear explosive device. Given the low current activity of radionuclides in water flowing from beneath the artificial cover (measured in Bq/dm³): ³H, 4–12; ⁹⁰Sr, 0.004–0.4, and diminishing levels of ²³⁹<sup>,</sup>²⁴⁰Pu (<10⁻⁶), the current migration of technogenic radionuclides with water is assessed as insignificant. Therefore, there is no immediate need for additional measures to strengthen or modify the block-rubble artificial cover.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 1","pages":"Article 100467"},"PeriodicalIF":0.0,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-13DOI: 10.1016/j.geogeo.2025.100465
André Mbabi Bitchong , Thierry Adatte , Serge P. Koah Na Lebogo , Cecile Olive Mbesse , Hamid Slimani , Jorge E. Spangenberg , Glwadys Ngo Mandeng , Simon Ngos III
The Paleocene–Eocene environment and vegetation evolution is widely documented worldwide. While a few similar studies have been undertaken in the Gulf of Guinea and the continental interior, they remain very limited, and provide no evidence of the Paleocene–Eocene thermal maximum (PETM). To address this gap, we conducted a comprehensive new sedimentological, palynological, mineralogical, and geochemical analysis of the Miang outcrop in the Douala Basin that encompasses silty-clayey deposits typical for swamp to back swamp coastal settings. The analysis of pollen and spore taxa, including Proxapertites operculatus, Proxapertites cursus, Echitriporites trianguliformis, Psilamonocolpites sp., Crototricolpites protoannemariae, Echitricolpites communis, Psilastephanocolporites sp., and Echimonocolpites rarispinosus and allowed the delineation of the pantropical Proxapertites operculatus Zone, corresponding to the Paleocene–Eocene transition, as well as Cameroon Spathiphyllum vanegensis (ZpI) and Retibrevitricolpites triangulatus (ZpII) zones, which indicate the late Paleocene and early Eocene epochs, respectively. This, combined with the organic carbon-isotope excursion (CIE: ∼-6.4‰), contributed to accurately determining the Paleocene–Eocene boundary (PEB). Geochemical and clay mineralogical data indicate that the paleoenvironment experienced intrusive volcanism linked with the Cameroon Volcanic Line (CVL), and enhanced primary productivity, both of which show marked decline prior to the PEB. Additionally, significant chemical alteration (CIA values: 85–94) occurred under warm and humid conditions (kaolinite: 70–88 % and smectite: 10–23 %), with sediments being reworked and deposited in a dysoxic setting conducive to organic matter preservation, especially from the pre-PETM period onwards. From the pre-PETM to early PETM, the Gulf of Guinea was probably covered by an extensive Lowland Rainforest/Open Forest ecosystem with a diverse flora, mostly angiosperms, that thrived in warm and humid conditions. From the mid-Lower Eocene onwards, Lowland Rainforest/Open Forest and Freshwater Swamp Forest species began to coexist with certain Mangrove-Coastal Swamp species, indicating proximity to the sea.
{"title":"Paleoenvironmental and vegetation evolution during the PETM in the Gulf of Guinea: A study based on integrated palynological and chemostratigraphic analysis of the Miang section in the Douala Basin, Cameroon","authors":"André Mbabi Bitchong , Thierry Adatte , Serge P. Koah Na Lebogo , Cecile Olive Mbesse , Hamid Slimani , Jorge E. Spangenberg , Glwadys Ngo Mandeng , Simon Ngos III","doi":"10.1016/j.geogeo.2025.100465","DOIUrl":"10.1016/j.geogeo.2025.100465","url":null,"abstract":"<div><div>The Paleocene–Eocene environment and vegetation evolution is widely documented worldwide. While a few similar studies have been undertaken in the Gulf of Guinea and the continental interior, they remain very limited, and provide no evidence of the Paleocene–Eocene thermal maximum (PETM). To address this gap, we conducted a comprehensive new sedimentological, palynological, mineralogical, and geochemical analysis of the Miang outcrop in the Douala Basin that encompasses silty-clayey deposits typical for swamp to back swamp coastal settings. The analysis of pollen and spore taxa, including <em>Proxapertites operculatus, Proxapertites cursus, Echitriporites trianguliformis, Psilamonocolpites</em> sp., <em>Crototricolpites protoannemariae, Echitricolpites communis, Psilastephanocolporites</em> sp., and <em>Echimonocolpites rarispinosus</em> and allowed the delineation of the pantropical <em>Proxapertites operculatus</em> Zone, corresponding to the Paleocene–Eocene transition, as well as Cameroon <em>Spathiphyllum vanegensis</em> (ZpI) and <em>Retibrevitricolpites triangulatus</em> (ZpII) zones, which indicate the late Paleocene and early Eocene epochs, respectively. This, combined with the organic carbon-isotope excursion (CIE: ∼-6.4‰), contributed to accurately determining the Paleocene–Eocene boundary (PEB). Geochemical and clay mineralogical data indicate that the paleoenvironment experienced intrusive volcanism linked with the Cameroon Volcanic Line (CVL), and enhanced primary productivity, both of which show marked decline prior to the PEB. Additionally, significant chemical alteration (CIA values: 85–94) occurred under warm and humid conditions (kaolinite: 70–88 % and smectite: 10–23 %), with sediments being reworked and deposited in a dysoxic setting conducive to organic matter preservation, especially from the pre-PETM period onwards. From the pre-PETM to early PETM, the Gulf of Guinea was probably covered by an extensive Lowland Rainforest/Open Forest ecosystem with a diverse flora, mostly angiosperms, that thrived in warm and humid conditions. From the mid-Lower Eocene onwards, Lowland Rainforest/Open Forest and Freshwater Swamp Forest species began to coexist with certain Mangrove-Coastal Swamp species, indicating proximity to the sea.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 1","pages":"Article 100465"},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-10DOI: 10.1016/j.geogeo.2025.100464
Nyakno J. George , Nsikak E. Bassey
Akwa Ibom State University (AKSU) in southeastern Nigeria faces recurrent waterlogging, poor drainage, and declining groundwater quality due to shallow water tables, low-permeability soils, intense rainfall, and unregulated land development. These issues have caused environmental degradation, hindered agriculture, and disrupted infrastructure. This study aims to evaluate the spatiotemporal hydrogeological and hydrochemical conditions of the AKSU campus to inform sustainable groundwater and drainage management. A combination of geophysical methods—vertical electrical sounding (VES) and electrical resistivity tomography (ERT)—was employed alongside hydrochemical analyses, data mining (Pareto and AHP), and irrigation suitability assessments. Field investigations involved 25 VES points and 2D ERT surveys, processed using WINRESIST and RES2DINV. Results identified 3–4 geoelectric layers, including productive sandy aquifers, with transmissivity values ranging from 1195.3 to 6611.6 m²/day and high correlations (R² > 0.9) between bulk aquifer resistivity and hydrodynamic parameters. Laboratory analyses showed that most groundwater samples met WHO standards, though localized exceedances of Fe, Pb, Cu, Mn, Ni, and fluoride were observed. Irrigation indices revealed that high sodium levels limit long-term agricultural suitability. Pareto and AHP analyses highlighted drainage density, rainfall, and topography as key contributors to waterlogging. The study concludes with recommendations for subsurface drainage systems, improved land use planning, and targeted water quality monitoring to support long-term environmental and agricultural resilience.
{"title":"Geoelectric and hydro-geochemical assessments of waterlogging and drainage for soil and agronomic groundwater evaluation at Akwa Ibom State University: Field and laboratory data mining approaches","authors":"Nyakno J. George , Nsikak E. Bassey","doi":"10.1016/j.geogeo.2025.100464","DOIUrl":"10.1016/j.geogeo.2025.100464","url":null,"abstract":"<div><div>Akwa Ibom State University (AKSU) in southeastern Nigeria faces recurrent waterlogging, poor drainage, and declining groundwater quality due to shallow water tables, low-permeability soils, intense rainfall, and unregulated land development. These issues have caused environmental degradation, hindered agriculture, and disrupted infrastructure. This study aims to evaluate the spatiotemporal hydrogeological and hydrochemical conditions of the AKSU campus to inform sustainable groundwater and drainage management. A combination of geophysical methods—vertical electrical sounding (VES) and electrical resistivity tomography (ERT)—was employed alongside hydrochemical analyses, data mining (Pareto and AHP), and irrigation suitability assessments. Field investigations involved 25 VES points and 2D ERT surveys, processed using WINRESIST and RES2DINV. Results identified 3–4 geoelectric layers, including productive sandy aquifers, with transmissivity values ranging from 1195.3 to 6611.6 m²/day and high correlations (R² > 0.9) between bulk aquifer resistivity and hydrodynamic parameters. Laboratory analyses showed that most groundwater samples met WHO standards, though localized exceedances of Fe, Pb, Cu, Mn, Ni, and fluoride were observed. Irrigation indices revealed that high sodium levels limit long-term agricultural suitability. Pareto and AHP analyses highlighted drainage density, rainfall, and topography as key contributors to waterlogging. The study concludes with recommendations for subsurface drainage systems, improved land use planning, and targeted water quality monitoring to support long-term environmental and agricultural resilience.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 1","pages":"Article 100464"},"PeriodicalIF":0.0,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1016/j.geogeo.2025.100463
Pooria Kianoush , Ahmad Adib , Shahab Varkouhi , Nasser Keshavarz Faraj Khah
The Torud Playa Basin in northeastern Iran possesses significant brine and hydrocarbon exploration potential. Its complex geology—comprising playa basins, evaporites, and multi-layered aquifers—presents unique challenges for pumping test implementation. The Torud Playa hydrogeological reserves were evaluated through multi-level pumping tests and hydrogeochemical analysis. These methods addressed the basin's complex evaporite geology. The study aims to understand reservoir behavior and develop effective management strategies, including improved water management practices and the identification of new exploration targets. The study's results have significantly contributed to understanding the reservoir behavior and developing effective management strategies. It is indicated that the studied area is divided into four sections, with poor permeability in the central parts (<1.5 m/day) and good permeability in the northern region (>3 m/day). This work identifies the north-northeastern parts of the Torud Playa suitable for potash reserves, with an estimated volume of 27,200.18 million cubic meters (Mm3) solutes in the playa and salt crust and an excavated volume of 18,133.45 Mm3. Sustainable exploitation requires limiting extraction to 40–60% of static reserves (327–490 Mm³) to maintain hydrological balance, with 90 % extraction causing 3.2 m water table decline and 62% habitat loss. These findings provide novel insights into reserve assessment methodologies for playa basins, integrating hydrodynamic and geochemical approaches to guide evidence-based resource management in arid regions.
{"title":"Comprehensive assessment of the Torud Playa Basin hydrogeological reserves in NE Iran: Insights from utilizing pumping test methods","authors":"Pooria Kianoush , Ahmad Adib , Shahab Varkouhi , Nasser Keshavarz Faraj Khah","doi":"10.1016/j.geogeo.2025.100463","DOIUrl":"10.1016/j.geogeo.2025.100463","url":null,"abstract":"<div><div>The Torud Playa Basin in northeastern Iran possesses significant brine and hydrocarbon exploration potential. Its complex geology—comprising playa basins, evaporites, and multi-layered aquifers—presents unique challenges for pumping test implementation. The Torud Playa hydrogeological reserves were evaluated through multi-level pumping tests and hydrogeochemical analysis. These methods addressed the basin's complex evaporite geology. The study aims to understand reservoir behavior and develop effective management strategies, including improved water management practices and the identification of new exploration targets. The study's results have significantly contributed to understanding the reservoir behavior and developing effective management strategies. It is indicated that the studied area is divided into four sections, with poor permeability in the central parts (<1.5 m/day) and good permeability in the northern region (>3 m/day). This work identifies the north-northeastern parts of the Torud Playa suitable for potash reserves, with an estimated volume of 27,200.18 million cubic meters (Mm<sup>3</sup>) solutes in the playa and salt crust and an excavated volume of 18,133.45 Mm<sup>3</sup>. Sustainable exploitation requires limiting extraction to 40–60% of static reserves (327–490 Mm³) to maintain hydrological balance, with 90 % extraction causing 3.2 m water table decline and 62% habitat loss. These findings provide novel insights into reserve assessment methodologies for playa basins, integrating hydrodynamic and geochemical approaches to guide evidence-based resource management in arid regions.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 1","pages":"Article 100463"},"PeriodicalIF":0.0,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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