Vol.58 No.1, February 28, 2025 Article TypeResearch PaperReview

• Research Paper 2025-02-28

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  Structural Geometry of the Taean Area in the Western Gyeonggi Massif, Korea: Insight from the Distribution Pattern of the Paleoproterozoic Seosan Group

  Seongjae Park, Yirang Jang, Minho Kang

  Econ. Environ. Geol. 2025; 58(1): 1-15

  Abstract

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  Abstract : The Seosan-Taean area on the Western Gyeonggi Massif of the Korean Peninsula preserves evidence of multiple geologic events from the Paleoproterozoic to the Early Mesozoic. The purpose of this study is to interpret the structural geometry of the Taean area that can explain the repetition of the Paleoproterozoic Seosan Group in the map. We have conducted structural geometry interpretation of the Taean area based on the various geological field data. Based on the variation in hinge orientations of the map-scale folds, the study area was subdivided into four structural domains (viz., northern, central, southern, and eastern domains). The hinges are plunging to the SW in the northern and southern, to the NE in the central and, to the SSW in the eastern domains. The results indicate the presence of a map-scale NW-vergent asymmetric syncline-anticline pair with NE-SW trending hinges in the northern, central and southern domains. If these results hold up to the eastern domain, the repetition of the Seosan Group in the study area can be attributed to the map-scale asymmetric syncline-anticline-syncline, which might be related to the development of regional faults in the Taean area. Further studies on the structural geometry, kinematics, and associated deformation conditions are required for a better understanding of the structural evolution of the Western Gyeonggi Massif, which will further provide insights into the crustal evolution of the Korean Peninsula since the Paleoproterozoic.

• Research Paper 2025-02-28

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  Application of High-Resolution Gravity and Magnetic Data for Fe-Mn-Pb Mineralization Prospecting in Jbel Skindis, Eastern High Atlas, Morocco

  Adnane Tobi, Mourad Essalhi, Said Es-Sabbar, Khaoula Qarqori, Mostapha Bouzekraoui, Abdelkarim Ait Baha, Ayoub Faou, Daoud El Azmi

  Econ. Environ. Geol. 2025; 58(1): 17-31

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  Abstract : The Boumaadine mineralized field has long been known as a principal mining area in the Jbel Skindis, Eastern High Atlas, Morocco. The present work focuses on the interpretation of high-resolution gravity and magnetic data, along with geological field data, for polymetallic mineralization prospecting in the Boumaadine area. The goal is to unravel the complex subsurface structures, identify potentially mineralized locations, and establish mining exploration guides at a regional scale. The calculated pole-reduced magnetic map and the residual gravity map highlight several anomalies mainly located in the Lower Liassic dolostones and the Triassic basalts, clay, and conglomerates. Enhancement techniques such as horizontal and vertical derivatives, analytic signal, and Euler deconvolution were applied to both maps. The results indicate that the anomalies follow the ENE-WSW and NNW-SSE directions, with depths ranging from 3 to 72 meters. Integration of geophysical data with geological field data improves the understanding of the relationships between gravity and magnetic anomalies and geological structures in the Boumaadine region. Detailed analysis suggests that the anomalies are primarily caused by sulfides and oxides orebodies clusters, supporting the genetic model proposed in previous studies. The findings have enabled us to draw up a map of the potentially mineralized areas in the study area which can be used in the tactical exploration phase. This approach can effectively identify promising areas within the entire Jbel Skindis and similar geological regions, reducing both time and exploration costs.

• Research Paper 2025-02-28

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  Mineralogical and Geochemical Evidence for Detecting K/Pg Boundary in Bade Section, Dohuk Area, Northern Iraq

  Shareef T. Al-Hamed, Sattar J. Al-Khafaji

  Econ. Environ. Geol. 2025; 58(1): 33-51

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  Abstract : The Cretaceous/Paleogene boundary (K/Pg) event, marked by the mineralogical and geochemical evidence and environmental catastrophes, is a contentious topic in geology. The mineralogical and geochemical anomalies at the K/Pg boundary worldwide were caused by an extraterrestrial object impact and/or prolonged Deccan eruptions at the end of the Mesozoic. The field observations show that the proposed K/Pg layer lies within the marl layers and consists of an iron layer composed of black spherules and matrix (iron spherule-rich layer). The petrographic study suggests that the sedimentation just below and above the K/Pg occurred in low-energy water, which preserved the iron spherule-rich layer in the sediments. Moreover, the XRD results reveal that the Upper Cretaceous and Lower Paleogene layers are composed of calcite, quartz, muscovite, and anatase, while the proposed K/Pg boundary (spherules and matrix) is predominantly of goethite and trace amounts of barite, giving it the name goethite layer. Goethite dominance and a sharp drop in calcite inside the goethite layer indicate that this layer marks the K/Pg boundary. The geochemical results indicate that the platinum group elements (PGEs) may be undetectable at concentrations below 5 ppb in Iraqi K/Pg boundary sites. The REE pattern suggests that the Bade sediments share the provenance, and the Ce/Ce* ratios propose they were deposited from seawater with a slight detrital influx from neighboring continental sediments. The positive Eu anomaly (Eu/Eu*) is mostly attributed to plagioclase absence in the Bade sediments. The elevated levels of Fe₂O₃, Ni, Co, Cr, Sc, V, Zr, Th, U, Pb, As, S, Sb, Zn, and Cu with CaO depletion within the goethite layer suggest that this layer represents the K/Pg. Additionally, the lowest total REE (ΣREE) content and the highest levels of SO₂ and SO₂/MnO at the goethite layer attest to its boundary status. The sudden increase of authigenic redox-sensitive elements (element/Al) and enrichment factors of U and Mo (U_EF and Mo_EF) indicates a change in redox conditions just within the goethite layer compared to the Upper Cretaceous and Lower Paleogene sediments, which means a rapid return to the oxygen conditions of the Upper Cretaceous after the K/Pg event. Furthermore, the sharp decline in the U/Mo ratio at the goethite layer supports the sulfidic-euxinic conditions that led to the development of pyrite. Based on this study's evidence, the goethite layer represents the K/Pg layer, and the Bade section is considered the perfect K/Pg boundary section in Iraq.

• Review 2025-02-28

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  Review of Pore-scale Reactive Transport Modeling for Microbial Processes in Subsurface Environments

  Seoyoung Son, Heewon Jung

  Econ. Environ. Geol. 2025; 58(1): 53-68

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  Abstract : Microorganisms play a central role in various biogeochemical processes in Earth’s near-surface environments. These microbial activities are not only controlled by the surrounding environmental conditions but also have a significant impact on the characteristics of their environments. Therefore, it is essential to quantitatively understand the interactions between microbial processes and their immediate surroundings at the pore scale for accurately estimating and predicting the fate of chemicals in subsurface environments. This study aims to provide a comprehensive review of previous mathematical modeling studies that focus on microbial activities at the pore-scale in subsurface environments. First, the fundamentals of three major pore scale reactive transport models are summarized: direct numerical simulation, lattice Boltzmann method, and pore network model. Then, we delve into the traditional modeling approach for microbe-mediated biochemical reactions and more rigorous mathematical models for biofilm development. Lastly, we explore recent advances in genome-scale metabolic models in the context of reactive transport modeling. By analyzing and synthesizing the previous studies, this study provides valuable insights into the intricate relationship between microbial processes and their immediate environments, contributing to a better understanding of biogeochemical dynamics in subsurface environments.

• Research Paper 2025-02-28

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  Media Analysis of Deep-sea Gas Field Exploration and Development Project in the East Sea

  Chan-Souk Kim, Hyun-Yong Park

  Econ. Environ. Geol. 2025; 58(1): 69-79

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  Abstract : This study examined the implications of media communication for the smooth execution of large-scale national projects, such as geological resource exploration, using media keyword network analysis and topic modeling analysis. The ‘Great Whale Project’ was analyzed based on 595 articles, divided into initial and later stages of media coverage. During the initial stage, President Yoon Sukyeol emerged as a major keyword, boosting information dissemination but also causing unnecessary controversy regarding the reliability and expertise of the information. This led to the issue of energy resources becoming politicized, with ongoing debates about the project's credibility and analysis expertise from both the initial and later stages. The later stage, emphasized the national and industrial significance of the project but continued to be plagued by political controversies. The study highlights the importance of optimal speaker, accuracy of information, and authority in media communication, especially for issues of great national and industrial significance like energy resources.

• Research Paper 2025-02-28

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  Spatial Pattern Analysis of Landslide Conditioning Factors in Jecheon Area Using SHAP Method

  Ji-Hee Choi, Jung-Hyun Lee, Hyuck-Jin Park, Daeung Yoon

  Econ. Environ. Geol. 2025; 58(1): 81-97

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  Abstract : AI models, which are frequently employed in landslide susceptibility analysis, are typically black-box models that lack the capacity to comprehend the analysis process. This deficiency can result in a reduction in the reliability of prediction results due to the challenge of comprehending the analysis or prediction process. To address this limitation, eXplainable AI (XAI) techniques are being utilized as a tool to explain the prediction process of AI models. Among the XAI techniques, prior studies have been predominantly conducted using SHapley Additive exPlanations (SHAP). However, the prevalent studies employing SHAP utilize it simply to express the influence of landslide occurrence factors in numerical values, thereby failing to adequately analyze the spatial correlation between landslide occurrence locations and landslide influence factors. Consequently, this study aims to visualize SHAP values in a spatial form to analyze the influence of the spatial distribution of factors on landslide susceptibility. To this end, ensemble models Adaptive Boost (AdaBoost), Random Forest, and eXtreme Gradient Boosting (XGBoost) were employed to analyze landslide susceptibility, and a landslide susceptibility map was constructed based on the calculated susceptibility index. The analysis revealed that the Random Forest and XGBoost models exhibited similar correlation between landslide occurrence and landslide influence factors. Consequently, a comparison of the importance of these factors was conducted using the SHAP summary plot of the two models. The evaluation identified four factors—forest height, standard deviation of planform curvature, standard deviation of standard curvature, and altitude—as having a significant impact on landslide occurrence. Furthermore, a spatial pattern analysis was conducted on the three factors that were deemed to be of high importance for the XGBoost model. This analysis was found to effectively reflect the effects of various factors in the SHAP summary plot. This facilitated an insightful examination of the contributions of the primary factors to landslide occurrence, guided by their spatial distribution, and enabled a thorough analysis of their influence on landslide susceptibility.