Journal of Asian Earth Sciences: X最新文献

Paleostress analysis on Paleozoic syn-depositional faults in the eastern Alborz, northern Iran 伊朗北部阿尔博尔斯东部古生代同沉积断裂的古应力分析

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2026-06-01 Epub Date: 2025-12-19 DOI: 10.1016/j.jaesx.2025.100213

Asghar Dolati , Jeroen Smit , Amin Behrooz , Alireza Shahidi , Mahmoud Ghafouri Fard , Liang Qiu

The Alborz Mountains of northern Iran stand out as an exceptional site for studying the Ediacaran-Paleozoic evolution of the northern Gondwana margin. The Alborz forms the inverted continental shelf of the Central Iranian microcontinent that was part of the northern Gondwana margin until the Permian period. Here, we present a paleostress analysis of the Paleozoic tectonic evolution in the eastern Alborz, supported by published studies of stratigraphy, petrology and regional tectonics. This analysis confirms and supplements the findings of a previous study in the central Alborz. The two studies complement each other. Late Neogene internal deformation has had less of an effect on the central Alborz, whereas the stratigraphy is more comprehensive in the eastern Alborz. The overall aim of the paleostress analysis in the central and eastern Alborz is to elucidate the Paleozoic structural-tectonic framework and the transition of geodynamic regimes, from the Cambrian active margin of Gondwana to the Permian Paleotethys post-rift passive margin of the Central Iranian Microcontinent. The paleostress tensor analysis of fault-slip data confirms that the Alborz Margin was dominated by a main N-S-directed (present-day reference frame) extension during the Paleozoic. This extension was nearly perpendicular to the main basin-bounding normal faults and the margin. The Paleozoic stress field remained unchanged during successive geodynamic regimes, from proto-Tethys subduction to Neotethys rifting. Research on past plate rotations and internal deformation in the Alborz and Central Iranian microcontinent may benefit from the findings.

伊朗北部的阿尔博尔斯山脉是研究冈瓦纳北部埃迪卡拉-古生代演化的一个特殊地点。Alborz形成了伊朗中部微大陆的倒置大陆架，直到二叠纪时期，该微大陆一直是冈瓦纳北部边缘的一部分。本文结合已发表的地层学、岩石学和区域构造学研究成果，对鄂尔多斯盆地东部古生代构造演化进行了古应力分析。这一分析证实并补充了先前在阿尔博尔斯中部进行的一项研究的结果。这两项研究相辅相成。晚新近纪内部变形对奥尔长斯中部的影响较小，而奥尔长斯东部的地层则较为全面。鄂博士中东部古应力分析的总体目的是阐明伊朗中部微大陆从寒武系冈瓦纳活动边缘到二叠纪古特提斯裂谷后被动边缘的古生代构造格局和地球动力学机制的转变。断层滑动资料的古应力张量分析证实，奥尔博兹边缘在古生代主要以南北向（现今参考框架）伸展为主。这一伸展几乎垂直于主要的盆缘正断层和边缘。从原特提斯俯冲到新特提斯裂陷，古生代应力场在连续的地球动力学机制中保持不变。研究阿尔布尔士和伊朗中部微大陆过去的板块旋转和内部变形可能会受益于这些发现。

{"title":"Paleostress analysis on Paleozoic syn-depositional faults in the eastern Alborz, northern Iran","authors":"Asghar Dolati , Jeroen Smit , Amin Behrooz , Alireza Shahidi , Mahmoud Ghafouri Fard , Liang Qiu","doi":"10.1016/j.jaesx.2025.100213","DOIUrl":"10.1016/j.jaesx.2025.100213","url":null,"abstract":"<div><div>The Alborz Mountains of northern Iran stand out as an exceptional site for studying the Ediacaran-Paleozoic evolution of the northern Gondwana margin. The Alborz forms the inverted continental shelf of the Central Iranian microcontinent that was part of the northern Gondwana margin until the Permian period. Here, we present a paleostress analysis of the Paleozoic tectonic evolution in the eastern Alborz, supported by published studies of stratigraphy, petrology and regional tectonics. This analysis confirms and supplements the findings of a previous study in the central Alborz. The two studies complement each other. Late Neogene internal deformation has had less of an effect on the central Alborz, whereas the stratigraphy is more comprehensive in the eastern Alborz. The overall aim of the paleostress analysis in the central and eastern Alborz is to elucidate the Paleozoic structural-tectonic framework and the transition of geodynamic regimes, from the Cambrian active margin of Gondwana to the Permian Paleotethys post-rift passive margin of the Central Iranian Microcontinent. The paleostress tensor analysis of fault-slip data confirms that the Alborz Margin was dominated by a main N-S-directed (present-day reference frame) extension during the Paleozoic. This extension was nearly perpendicular to the main basin-bounding normal faults and the margin. The Paleozoic stress field remained unchanged during successive geodynamic regimes, from proto-Tethys subduction to Neotethys rifting. Research on past plate rotations and internal deformation in the Alborz and Central Iranian microcontinent may benefit from the findings.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"15 ","pages":"Article 100213"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145799800","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}

引用次数: 0

Tectonic evolution of cratonic blocks and orogenic belts of the Tethys domain in Asia: Preface 亚洲特提斯地区克拉通地块与造山带的构造演化

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2026-06-01 Epub Date: 2026-01-13 DOI: 10.1016/j.jaesx.2026.100215

Liang Qiu , Dan-Ping Yan , Wentao Cao , Suzanne Autrey , Suoya Fan , Yiduo Liu , Yiwen Zhou , Xicheng Wang , Ferdous Jamal

引用次数: 0

Novel regional–residual anomaly separation technique for evaluating Moho configuration and crustal density structure beneath the East Vietnam Sea (South China Sea) 新的区域-残余异常分离技术评价东越南海（南海）莫霍剖面和地壳密度结构

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-11-27 DOI: 10.1016/j.jaesx.2025.100210

Nguyen Kim Dung , Ebong Dickson Ebong , David Gomez-Ortiz , Zaidoon Taha Abdulrazzaq , Hussein Abdulrahim Al-Saady , Tran Tuan Dung , Tran Van Kha , Nguyen Ba Dai , Tran Tuan Duong

This study presents a novel gravity anomaly separation technique and demonstrates its application in delineating the crustal density structure and Moho depth configuration of the East Vietnam Sea (South China Sea). The proposed method employs correlation analysis between Bouguer gravity anomalies approximated by higher-order two-variable polynomial functions and their upward-continued counterparts at varying altitudes to isolate the regional gravity field. The resulting regional component, associated with long-wavelength gravity signals, was used to model the depth to the Moho boundary, while the residual component, reflecting short-wavelength anomalies, was inverted to estimate lateral variations in crustal density. The results reveal that crustal density varies from approximately 2.54 g/cm³ in sedimentary basins to about 2.90 g/cm³ along the mid-oceanic ridge, indicating significant lithological contrasts. The Moho depth ranges from ∼8 km beneath the mid-oceanic ridge to ∼32 km beneath the southwestern margin, particularly near the Red River basin. These observations correlated well with previous interpretations derived from ocean bottom seismometer data, validating the effectiveness of the approach. This study develops an integrated regional–residual separation and inversion framework that refines constraints on crustal architecture while offering critical geodynamic insights for delineating tectonic domains with potential resource significance. It offers a new perspective for gravity-based crustal modeling and provides a first-order geophysical framework for understanding the lithospheric structure of the East Vietnam Sea. The method also demonstrates potential for global and broader applications in tectonic studies and regional geodynamic investigations.

提出了一种新的重力异常分离技术，并论证了该技术在东越南海（南海）地壳密度结构和莫霍面深度配置圈定中的应用。该方法利用高阶二变量多项式函数近似的布格重力异常与不同高度上连的布格重力异常之间的相关性分析，隔离区域重力场。得到的区域分量与长波长重力信号相关，用于模拟莫霍边界的深度，而反映短波长的剩余分量则用于反演地壳密度的横向变化。结果表明，沉积盆地的地壳密度约为2.54 g/cm3，洋中脊的地壳密度约为2.90 g/cm3，具有明显的岩性差异。莫霍线深度从洋中脊下~ 8 km到西南缘下~ 32 km，特别是在红河盆地附近。这些观测结果与以前从海底地震仪数据得出的解释相吻合，证实了该方法的有效性。该研究开发了一个综合的区域-残余分离和反演框架，该框架细化了对地壳结构的约束，同时为圈定具有潜在资源意义的构造域提供了关键的地球动力学见解。它为基于重力的地壳模拟提供了新的视角，并为认识东越南海岩石圈结构提供了一阶地球物理框架。该方法还显示了在构造研究和区域地球动力学调查中全球和更广泛应用的潜力。

{"title":"Novel regional–residual anomaly separation technique for evaluating Moho configuration and crustal density structure beneath the East Vietnam Sea (South China Sea)","authors":"Nguyen Kim Dung , Ebong Dickson Ebong , David Gomez-Ortiz , Zaidoon Taha Abdulrazzaq , Hussein Abdulrahim Al-Saady , Tran Tuan Dung , Tran Van Kha , Nguyen Ba Dai , Tran Tuan Duong","doi":"10.1016/j.jaesx.2025.100210","DOIUrl":"10.1016/j.jaesx.2025.100210","url":null,"abstract":"<div><div>This study presents a novel gravity anomaly separation technique and demonstrates its application in delineating the crustal density structure and Moho depth configuration of the East Vietnam Sea (South China Sea). The proposed method employs correlation analysis between Bouguer gravity anomalies approximated by higher-order two-variable polynomial functions and their upward-continued counterparts at varying altitudes to isolate the regional gravity field. The resulting regional component, associated with long-wavelength gravity signals, was used to model the depth to the Moho boundary, while the residual component, reflecting short-wavelength anomalies, was inverted to estimate lateral variations in crustal density. The results reveal that crustal density varies from approximately 2.54 g/cm<sup>3</sup> in sedimentary basins to about 2.90 g/cm<sup>3</sup> along the mid-oceanic ridge, indicating significant lithological contrasts. The Moho depth ranges from ∼8 km beneath the mid-oceanic ridge to ∼32 km beneath the southwestern margin, particularly near the Red River basin. These observations correlated well with previous interpretations derived from ocean bottom seismometer data, validating the effectiveness of the approach. This study develops an integrated regional–residual separation and inversion framework that refines constraints on crustal architecture while offering critical geodynamic insights for delineating tectonic domains with potential resource significance. It offers a new perspective for gravity-based crustal modeling and provides a first-order geophysical framework for understanding the lithospheric structure of the East Vietnam Sea. The method also demonstrates potential for global and broader applications in tectonic studies and regional geodynamic investigations.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100210"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614385","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}

引用次数: 0

Potential of random forest machine learning algorithm for geological mapping using PALSAR and Sentinel-2A remote sensing data: A case study of Tsagaan-uul area, southern Mongolia 随机森林机器学习算法在利用PALSAR和Sentinel-2A遥感数据进行地质填图中的潜力——以蒙古南部察干乌尔地区为例

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-08-01 DOI: 10.1016/j.jaesx.2025.100204

Munkhsuren Badrakh , Narantsetseg Tserendash , Erdenejargal Choindonjamts , Gáspár Albert

Geological mapping in remote and geologically complex regions can be substantially improved by integrating remote sensing data with machine learning algorithms. This study evaluates the effectiveness of the Random Forest algorithm for geological mapping in the Tsagaan-uul area of the Khatanbulag ancient massif, Mongolia, a region characterized by limited accessibility and sparse field data. A comprehensive set of predictor variables was used, including Sentinel-2A spectral bands and indices, ALOS PALSAR digital elevation model, and terrain morphometric features. Two distinct training strategies were employed: (1) based on a geological map, (2) based on field-collected rock samples from two lithologically diverse formations. Variable importance was assessed using the Mean Decrease Gini index, while classification performance was measured through overall accuracy, precision, recall, F1-score, and the Kappa coefficient. In the first experiment, ALOS PALSAR DEM and Terrain Ruggedness Index were identified as the most influential predictors. Overall accuracy across all nine models ranged from 59.9 % to 64.4 %, with Kappa coefficients between 0.508 and 0.562. Model 1, which used a 90–10 % split, achieved the highest performance, while Model 4 recorded the lowest. These suggest that the data split ratio had a greater impact on model accuracy than the number of decision trees. In the second experiment, variations in the number of trees and variables per split had minimal effects, whereas the choice of stratification method significantly affected model outcomes. Overall, findings emphasize the critical role of dataset configuration, such as class balance and representative sampling, in optimizing Random Forest-based geological mapping.

通过将遥感数据与机器学习算法相结合，可以大大改善偏远和地质复杂地区的地质填图。本文评价了随机森林算法在蒙古可汗布拉克古地块察干乌尔地区地质填图中的有效性，该地区具有可及性有限、野外数据稀疏的特点。使用了一套综合的预测变量，包括Sentinel-2A光谱带和指数、ALOS PALSAR数字高程模型和地形形态特征。采用了两种不同的训练策略：(1)基于地质图，(2)基于从两个岩性不同的地层中现场采集的岩石样本。变量重要性评估使用平均减少基尼指数，而分类性能通过总体准确性，精密度，召回率，f1得分和Kappa系数来衡量。在第一个实验中，ALOS PALSAR DEM和地形崎岖度指数被确定为最具影响力的预测因子。所有9个模型的总体准确率在59.9%到64.4%之间，Kappa系数在0.508到0.562之间。使用90 - 10%分割的模型1获得了最高的性能，而模型4则记录了最低的性能。这表明数据分割率比决策树数量对模型精度的影响更大。在第二个实验中，每次分裂的树和变量数量的变化影响很小，而分层方法的选择显著影响模型结果。总体而言，研究结果强调了数据集配置（如类别平衡和代表性采样）在优化基于随机森林的地质填图中的关键作用。

{"title":"Potential of random forest machine learning algorithm for geological mapping using PALSAR and Sentinel-2A remote sensing data: A case study of Tsagaan-uul area, southern Mongolia","authors":"Munkhsuren Badrakh , Narantsetseg Tserendash , Erdenejargal Choindonjamts , Gáspár Albert","doi":"10.1016/j.jaesx.2025.100204","DOIUrl":"10.1016/j.jaesx.2025.100204","url":null,"abstract":"<div><div>Geological mapping in remote and geologically complex regions can be substantially improved by integrating remote sensing data with machine learning algorithms. This study evaluates the effectiveness of the Random Forest algorithm for geological mapping in the Tsagaan-uul area of the Khatanbulag ancient massif, Mongolia, a region characterized by limited accessibility and sparse field data. A comprehensive set of predictor variables was used, including Sentinel-2A spectral bands and indices, ALOS PALSAR digital elevation model, and terrain morphometric features. Two distinct training strategies were employed: (1) based on a geological map, (2) based on field-collected rock samples from two lithologically diverse formations. Variable importance was assessed using the Mean Decrease Gini index, while classification performance was measured through overall accuracy, precision, recall, F1-score, and the Kappa coefficient. In the first experiment, ALOS PALSAR DEM and Terrain Ruggedness Index were identified as the most influential predictors. Overall accuracy across all nine models ranged from 59.9 % to 64.4 %, with Kappa coefficients between 0.508 and 0.562. Model 1, which used a 90–10 % split, achieved the highest performance, while Model 4 recorded the lowest. These suggest that the data split ratio had a greater impact on model accuracy than the number of decision trees. In the second experiment, variations in the number of trees and variables per split had minimal effects, whereas the choice of stratification method significantly affected model outcomes. Overall, findings emphasize the critical role of dataset configuration, such as class balance and representative sampling, in optimizing Random Forest-based geological mapping.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100204"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144758050","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}

引用次数: 0

Cenozoic exhumation of the North Qinling Range: Insights from apatite and zircon (U-Th)/He thermochronology 北秦岭新生代发掘：磷灰石和锆石(U-Th)/He热年代学的启示

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-09-08 DOI: 10.1016/j.jaesx.2025.100207

Jin Liu, Yubo Wang, Xiao Ding, Junwei Wang

The Cenozoic uplift of the North Qinling Range has profoundly influenced climatic and ecological patterns across northern and southern China. However, key aspects of this orogenic event, including its principal phase(s) of exhumation, total magnitude, and detailed evolutionary processes remain poorly constrained. We present a series of apatite and zircon (U-Th)/He ages from a drill core and surface relief of Zhongnan Mt., in the middle part of North Qinling Range. Comparative analysis of apatite (U-Th)/He age discrepancies between drill core and surface samples provides a perspective to figure out variation of isotherms and then helps figure out that fault activity and topographic wave length were dominant controls on isotherm geometry in the study area. The composite vertical pseudo-transect constructed from apatite and zircon (U-Th)/He ages indicates a very fast cooling period since at least ∼ 82.7 Ma and lasted to 77 Ma, followed by a relatively slow cooling stage until 49 Ma, and then a slow cooling period to 33 Ma. These three exhumation stages are widely documented in the adjacent region, with the subduction of the Pacific Plate considered the primary driving mechanism.

新生代北秦岭隆升深刻影响了中国南北的气候和生态格局。然而，这次造山事件的关键方面，包括它的主要掘出阶段、总规模和详细的演化过程，仍然知之甚少。本文从北秦岭中段终南山岩心和地表起伏中获得了一系列磷灰石和锆石(U-Th)/He年龄。对比分析岩心与地表样品的磷灰石(U-Th)/He年龄差异，为研究区等温线的变化提供了一个视角，从而有助于了解断层活动性和地形波长是研究区等温线几何形状的主要控制因素。由磷灰石和锆石(U-Th)/He年龄构成的复合垂直伪样带表明，该区至少从~ 82.7 Ma开始经历了一个非常快速的冷却期，并持续到77 Ma，随后是一个相对缓慢的冷却期，直到49 Ma，然后是一个缓慢冷却期，直到33 Ma。这三个掘出阶段在邻近地区有广泛的记载，太平洋板块的俯冲作用被认为是主要的驱动机制。

{"title":"Cenozoic exhumation of the North Qinling Range: Insights from apatite and zircon (U-Th)/He thermochronology","authors":"Jin Liu, Yubo Wang, Xiao Ding, Junwei Wang","doi":"10.1016/j.jaesx.2025.100207","DOIUrl":"10.1016/j.jaesx.2025.100207","url":null,"abstract":"<div><div>The Cenozoic uplift of the North Qinling Range has profoundly influenced climatic and ecological patterns across northern and southern China. However, key aspects of this orogenic event, including its principal phase(s) of exhumation, total magnitude, and detailed evolutionary processes remain poorly constrained. We present a series of apatite and zircon (U-Th)/He ages from a drill core and surface relief of Zhongnan Mt., in the middle part of North Qinling Range. Comparative analysis of apatite (U-Th)/He age discrepancies between drill core and surface samples provides a perspective to figure out variation of isotherms and then helps figure out that fault activity and topographic wave length were dominant controls on isotherm geometry in the study area. The composite vertical pseudo-transect constructed from apatite and zircon (U-Th)/He ages indicates a very fast cooling period since at least ∼ 82.7 Ma and lasted to 77 Ma, followed by a relatively slow cooling stage until 49 Ma, and then a slow cooling period to 33 Ma. These three exhumation stages are widely documented in the adjacent region, with the subduction of the Pacific Plate considered the primary driving mechanism.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100207"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018989","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}

引用次数: 0

Contrasting characteristics observed between the early and late Cretaceous periods: Evidences from geochemical and isotopic studies of clastic rocks from the Tethys Himalaya, India 早白垩世和晚白垩世的对比特征：来自印度特提斯-喜马拉雅地区碎屑岩地球化学和同位素研究的证据

IF 1.7 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-07-24 DOI: 10.1016/j.jaesx.2025.100202

Heena Khan , Javid A. Ganai , Shaik A. Rashid , Nurul Absar

This study uses a multi-proxy approach on Cretaceous shales (consisting of early Cretaceous Giumal shale and late Cretaceous Chikkim shale of Lagudarsi Group) from the Spiti region of the Indian Tethys Himalaya to assess paleo-weathering, redox conditions, paleoclimate, provenance characteristics and tectonic setting. Geochemical weathering indices such as the Chemical Index of Alteration (CIA), Weathering Index of Parker (WIP) and Ca-free weathering indices (CIX) suggest a shift in weathering intensity from low to high degrees during the Cretaceous period in the source area, also shown in the Al₂O₃–CaO* + Na₂O–K₂O (A–CN–K) diagram. Redox-sensitive trace element ratios like V/(V + Ni), V/Sc and Ce anomalies, Total Organic Carbon (TOC), δ¹³C and δ³⁴S values indicate an anoxic marine depositional environment, documenting an ocean anoxic event (OAE). Provenance discrimination diagrams and geochemical ratios incorporating Nd–Sr isotopes indicate a felsic-dominant source for early Cretaceous Giumal shale and a more mafic-dominant source for late Cretaceous Chikkim shale. Geochemical proxies (Rb/Sr, Mg/Ca, Al/K and CIA) record a shift from humid (non-glacial) climate during the early Cretaceous to cold (glacial) climate during the late Cretaceous. Discriminant diagrams (K₂O/Na₂O–SiO₂, La/Sc–Ti/Zr, and La–Th–Sc) suggest a passive margin tectonic setting for the early Cretaceous, whereas an active continental margin for late Cretaceous shale in the Spiti region. These findings provide insights into the climatic and tectonic evolution of the Indian Tethys Himalaya during the Cretaceous period, contributing to the understanding of global anoxic events and regional sedimentary and tectonic history.

以印度特提斯-喜马拉雅山脉斯皮提地区白垩系（Lagudarsi组早白垩世Giumal页岩和晚白垩世Chikkim页岩）为研究对象，采用多代理方法评价了古风化、氧化还原条件、古气候、物源特征和构造背景。化学蚀变指数（CIA）、帕克风化指数（WIP）和无ca风化指数（CIX）等地球化学风化指标表明，白垩纪烃源区风化强度由低向高转变，也体现在Al2O3-CaO * + Na2O-K2O （a- cn - k）图中。V/(V + Ni)、V/Sc和Ce等对氧化还原敏感的微量元素比值异常、总有机碳（TOC）、δ13C和δ34S值表明海洋沉积环境缺氧，记录了海洋缺氧事件（OAE）。含Nd-Sr同位素的物源鉴别图和地球化学比值表明，早白垩世第三系页岩的物源以长质岩为主，晚白垩世奇金页岩的物源以镁质岩为主。地球化学指标Rb/Sr、Mg/Ca、Al/K和CIA记录了早白垩世湿润（非冰期）气候向晚白垩世寒冷（冰期）气候的转变。判别图（K2O/ Na2O-SiO2、La/ Sc-Ti /Zr和La - th - sc）表明Spiti地区早白垩世为被动边缘构造环境，而晚白垩世页岩则为活动大陆边缘构造环境。这些发现有助于了解白垩纪印度特提斯-喜马拉雅地区的气候和构造演化，有助于了解全球缺氧事件和区域沉积和构造历史。

{"title":"Contrasting characteristics observed between the early and late Cretaceous periods: Evidences from geochemical and isotopic studies of clastic rocks from the Tethys Himalaya, India","authors":"Heena Khan , Javid A. Ganai , Shaik A. Rashid , Nurul Absar","doi":"10.1016/j.jaesx.2025.100202","DOIUrl":"10.1016/j.jaesx.2025.100202","url":null,"abstract":"<div><div>This study uses a multi-proxy approach on Cretaceous shales (consisting of early Cretaceous Giumal shale and late Cretaceous Chikkim shale of Lagudarsi Group) from the Spiti region of the Indian Tethys Himalaya to assess paleo-weathering, redox conditions, paleoclimate, provenance characteristics and tectonic setting. Geochemical weathering indices such as the Chemical Index of Alteration (CIA), Weathering Index of Parker (WIP) and Ca-free weathering indices (CIX) suggest a shift in weathering intensity from low to high degrees during the Cretaceous period in the source area, also shown in the Al<sub>2</sub>O<sub>3</sub>–CaO*+Na<sub>2</sub>O–K<sub>2</sub>O (A–CN–K) diagram. Redox-sensitive trace element ratios like V/(V + Ni), V/Sc and Ce anomalies, Total Organic Carbon (TOC), δ<sup>13</sup>C and δ<sup>34</sup>S values indicate an anoxic marine depositional environment, documenting an ocean anoxic event (OAE). Provenance discrimination diagrams and geochemical ratios incorporating Nd–Sr isotopes indicate a felsic-dominant source for early Cretaceous Giumal shale and a more mafic-dominant source for late Cretaceous Chikkim shale. Geochemical proxies (Rb/Sr, Mg/Ca, Al/K and CIA) record a shift from humid (non-glacial) climate during the early Cretaceous to cold (glacial) climate during the late Cretaceous. Discriminant diagrams (K<sub>2</sub>O/Na<sub>2</sub>O–SiO<sub>2</sub>, La/Sc–Ti/Zr, and La–Th–Sc) suggest a passive margin tectonic setting for the early Cretaceous, whereas an active continental margin for late Cretaceous shale in the Spiti region. These findings provide insights into the climatic and tectonic evolution of the Indian Tethys Himalaya during the Cretaceous period, contributing to the understanding of global anoxic events and regional sedimentary and tectonic history.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100202"},"PeriodicalIF":1.7,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703089","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}

引用次数: 0

Morphogenesis of the Holocene coastal landforms on Sumba Island, Indonesia 印度尼西亚松巴岛全新世海岸地貌的形态发生

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-09-11 DOI: 10.1016/j.jaesx.2025.100208

Denovan Chauveau , Kevin Pedoja , Christine Authemayou , Laurent Husson , Gino de Gelder , Sonny Aribowo , Mary Elliot , Julius Jara–Muñoz , Anne-Morwenn Pastier , Danny Hilman Natawidjaja , Vera Christanti Agusta , Sri Yudawati Cahyarini

Coastal terraces, whether erosional, depositional, or bio-constructed, have been widely used to quantify Late Cenozoic vertical deformation and relative sea-level changes. Here, we review and investigate the Holocene coastal terraces of Sumba Island, Indonesia. We describe fifteen coastal sites, evenly distributed between the South and North coasts. The terraces are Holocene age, based on ¹⁴C and U/Th ages. We show that the preservation of coastal terraces in Sumba is favoured on the leeward coast (North). Holocene and older Pleistocene coastal terraces are almost absent on the windward coast (South), although modern coral reefs almost ubiquitously thrive. The morphology and the nature of the bedrock varies between the two sides of the island: while sequences of earlier Pleistocene coral reef limestones dominate in the North, Miocene/Pliocene tuffs and pelagic carbonates outcrop on the southern coast. The elevations of the Holocene inner edges range from 2.4 ± 0.7 to 6.9 ± 0.7 m above the present mean sea level. Despite disparate uplift rates, the three preserved windward terraces (out of the seven sites investigated) generally have a higher inner edge than leeward terraces. We conclude that neither glacio-eustatic oscillations, vertical deformation rates nor hydrodynamics by themselves can explain the variability in inner edge elevations on Sumba, but only a complex combination of these processes. Finally, our study serves as a solid basis for future investigation of the Holocene landforms of the island of Sumba and other similar tropical coastal zones.

海岸阶地，无论是侵蚀的、沉积的还是生物构造的，都被广泛用于量化晚新生代垂直变形和相对海平面变化。本文对印度尼西亚松巴岛全新世海岸阶地进行了回顾和研究。我们描述了15个沿海地点，均匀分布在南北海岸之间。根据14C和U/Th年龄，阶地为全新世。我们表明，保存沿海梯田在松巴是有利的背风海岸（北）。在向风海岸（南），虽然现代珊瑚礁几乎无处不在，但全新世和更古老的更新世海岸梯田几乎没有。岛的两侧基岩的形态和性质各不相同：北部主要是更新世早期的珊瑚礁灰岩，南部海岸则是中新世/上新世的凝灰岩和远洋碳酸盐岩。全新世内缘海拔高度在2.4±0.7 ~ 6.9±0.7 m之间。尽管隆升率不同，但在调查的七个地点中，三个保存完好的迎风梯田通常比背风梯田具有更高的内边缘。我们得出结论，无论是冰川-上升振荡、垂直变形速率还是流体动力学本身都不能解释松巴内缘海拔的变化，而只能是这些过程的复杂组合。最后，本研究为今后对松巴岛及其他类似热带沿海地区全新世地貌的研究提供了坚实的基础。

{"title":"Morphogenesis of the Holocene coastal landforms on Sumba Island, Indonesia","authors":"Denovan Chauveau , Kevin Pedoja , Christine Authemayou , Laurent Husson , Gino de Gelder , Sonny Aribowo , Mary Elliot , Julius Jara–Muñoz , Anne-Morwenn Pastier , Danny Hilman Natawidjaja , Vera Christanti Agusta , Sri Yudawati Cahyarini","doi":"10.1016/j.jaesx.2025.100208","DOIUrl":"10.1016/j.jaesx.2025.100208","url":null,"abstract":"<div><div>Coastal terraces, whether erosional, depositional, or bio-constructed, have been widely used to quantify Late Cenozoic vertical deformation and relative sea-level changes. Here, we review and investigate the Holocene coastal terraces of Sumba Island, Indonesia. We describe fifteen coastal sites, evenly distributed between the South and North coasts. The terraces are Holocene age, based on <sup>14</sup>C and U/Th ages. We show that the preservation of coastal terraces in Sumba is favoured on the leeward coast (North). Holocene and older Pleistocene coastal terraces are almost absent on the windward coast (South), although modern coral reefs almost ubiquitously thrive. The morphology and the nature of the bedrock varies between the two sides of the island: while sequences of earlier Pleistocene coral reef limestones dominate in the North, Miocene/Pliocene tuffs and pelagic carbonates outcrop on the southern coast. The elevations of the Holocene inner edges range from 2.4 ± 0.7 to 6.9 ± 0.7 m above the present mean sea level. Despite disparate uplift rates, the three preserved windward terraces (out of the seven sites investigated) generally have a higher inner edge than leeward terraces. We conclude that neither glacio-eustatic oscillations, vertical deformation rates nor hydrodynamics by themselves can explain the variability in inner edge elevations on Sumba, but only a complex combination of these processes. Finally, our study serves as a solid basis for future investigation of the Holocene landforms of the island of Sumba and other similar tropical coastal zones.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100208"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048748","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}

引用次数: 0

Structural and geochronological constraints on the Permo-Triassic tectonic evolution of the southern Jinsha Orogenic Belt, eastern Tibetan Plateau

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-10-30 DOI: 10.1016/j.jaesx.2025.100209

Xu-Tuo Li , Dan-Ping Yan , Liang Qiu , Michael L. Wells , Xu-Xuan Ma

The southern Jinsha Orogenic Belt records the subduction-accretion-collision processes during the closure of the Paleo-Jinsha Ocean. Detailed structural analysis conducted along this belt and U-Pb zircon dating of tectonic-related plutons put robust constraints on a three-stage deformation history of the southern Jinsha orogenesis. The D₁ deformation is developed within the high-grade metamorphic complex. Based on parallelism between multiscale structures, two plutons (SK21-1 & −2) are inferred as syntectonic and constrain the D₁ deformation to Middle Permian (269 ∼ 267 Ma). The D₂ deformation is characterized by pervasive fabrics outcropped through the whole belt. An internal undeformed pluton (SK18), which was affected by the D₂ deformation at its margin, combined with post-D₂ plutons, constrain the D₂ deformation to 258 ∼ 240 Ma. The D₃ deformation is interpreted as a local effect of pluton diapirism due to its density-driven vertical structures and limited range of distribution, rather than a regional deformation. Combined with previous published Early Permian to Late Triassic geological records, we propose that the D₁ deformation records an accretionary orogenesis during the subduction of the southern Jinsha oceanic lithosphere, the D₂ deformation represents the Early-Middle Triassic continental collision between the eastern Qiangtang terrane and Zhongza massif, and the D₃ deformation was generated by the post-collisional pluton diapirism. Moreover, based on the uniformly west-dipping S₂ foliations and west-plunging L₂ lineations with local west-side up, we suggest a westward subduction of the southern Jinsha oceanic plate.

南金沙造山带记录了古金沙洋闭合时期的俯冲-增生-碰撞过程。通过对该构造带的详细构造分析和构造相关岩体的U-Pb锆石定年，对金沙南部造山运动的三阶段变形史进行了强有力的约束。D1变形发育于高变质杂岩内。基于多尺度构造之间的平行性，推断两个岩体（SK21-1 &−2）为同构造，并将D1变形限制在中二叠统（269 ~ 267 Ma）。D2变形的特征是织物在整个带中普遍伸出。受D2变形影响的内部未变形岩体（SK18）与D2后岩体结合，将D2变形限制在258 ~ 240 Ma。D3的变形由于其密度驱动的垂直构造和有限的分布范围而被解释为深部底辟作用的局部效应，而不是区域性变形。结合已有的早二叠世—晚三叠世地质记录，认为D1变形记录了南金沙洋岩石圈俯冲时的增生造山作用，D2变形代表了早中三叠世羌塘地块东部与中杂地块的大陆碰撞作用，D3变形是碰撞后的岩体底液作用。S2片理均匀西倾，L2线理西倾，局部西侧上展，表明金沙南洋板块向西俯冲。

{"title":"Structural and geochronological constraints on the Permo-Triassic tectonic evolution of the southern Jinsha Orogenic Belt, eastern Tibetan Plateau","authors":"Xu-Tuo Li , Dan-Ping Yan , Liang Qiu , Michael L. Wells , Xu-Xuan Ma","doi":"10.1016/j.jaesx.2025.100209","DOIUrl":"10.1016/j.jaesx.2025.100209","url":null,"abstract":"<div><div>The southern Jinsha Orogenic Belt records the subduction-accretion-collision processes during the closure of the Paleo-Jinsha Ocean. Detailed structural analysis conducted along this belt and U-Pb zircon dating of tectonic-related plutons put robust constraints on a three-stage deformation history of the southern Jinsha orogenesis. The D<sub>1</sub> deformation is developed within the high-grade metamorphic complex. Based on parallelism between multiscale structures, two plutons (SK21-1 & −2) are inferred as syntectonic and constrain the D<sub>1</sub> deformation to Middle Permian (269 ∼ 267 Ma). The D<sub>2</sub> deformation is characterized by pervasive fabrics outcropped through the whole belt. An internal undeformed pluton (SK18), which was affected by the D<sub>2</sub> deformation at its margin, combined with post-D<sub>2</sub> plutons, constrain the D<sub>2</sub> deformation to 258 ∼ 240 Ma. The D<sub>3</sub> deformation is interpreted as a local effect of pluton diapirism due to its density-driven vertical structures and limited range of distribution, rather than a regional deformation. Combined with previous published Early Permian to Late Triassic geological records, we propose that the D<sub>1</sub> deformation records an accretionary orogenesis during the subduction of the southern Jinsha oceanic lithosphere, the D<sub>2</sub> deformation represents the Early-Middle Triassic continental collision between the eastern Qiangtang terrane and Zhongza massif, and the D<sub>3</sub> deformation was generated by the post-collisional pluton diapirism. Moreover, based on the uniformly west-dipping S<sub>2</sub> foliations and west-plunging L<sub>2</sub> lineations with local west-side up, we suggest a westward subduction of the southern Jinsha oceanic plate.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100209"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145415653","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}

引用次数: 0

Mineralogy and provenance of red clay soils in Barind and Madhupur clay formations, Bangladesh: Implications for tectonic setting and chemical weathering 孟加拉国Barind和Madhupur粘土地层中红粘土的矿物学和物源：构造环境和化学风化的意义

IF 1.7 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-06-23 DOI: 10.1016/j.jaesx.2025.100200

Md.Golam Mostafa , Md.Aminur Rahman , Pradip Kumar Biswas , Abu Reza Md. Towfiqul Islam , Md.Ripaj Uddin , Hayatullah , Md.Nakib Hossen , Md. Nuruzzaman , Abu Yousuf , Md. Hasnain Mustak , Md. Shohel Rana

This study investigates the geochemical and mineralogical properties of the Barind and Madhupur clay formations in the Bengal Basin, focusing on their provenance, tectonic setting and weathering processes in relation to regional geological evolution. Several techniques such as particle size distribution, X-ray diffraction (XRD), X-ray fluorescence (XRF), atomic absorption spectrometry (AAS) and geochemical weathering indices were applied to analyze the mineralogical, chemical and heavy metal characteristics of red clay soils. The particle size distribution reveals that the soil consists predominantly of fine-grained silt (∼80 %), with minor amounts of clay and sand, influenced by pedogenesis and weathering processes. Mineralogical analysis reveals dominance of quartz, kaolinite, illite, chlorite and iron oxides, suggesting a mix of weathered metamorphic and sedimentary rocks and intense weathering in a humid, cold Pleistocene climate. Geochemical data show high concentrations of SiO₂, indicating a quartz-rich source with a mature mineralogical composition. Principal component analysis (PCA) points to extensive weathering, particularly of mafic rocks. Chemical index of alteration (CIA) values ranges from 70.93 % to 90.80 %, indicating moderate to intense weathering. Trace metal concentrations are lower than the average Upper Continental Crust, suggesting long-term weathering. These findings underscore the role of humid, cold climates and tectonic setting in shaping the Bengal Basin’s Pleistocene landscapes. The study advances regional paleoclimatic reconstructions and highlights the interplay of Himalayan erosion, fluvial transport and chemical weathering in producing the distinctive red clay soils. Future work should integrate isotopic tracing to refine sediment source apportionment and climatic models.

本文研究了孟加拉盆地Barind和Madhupur粘土组的地球化学和矿物学特征，重点研究了它们的物源、构造背景和风化过程与区域地质演化的关系。采用粒度分布、x射线衍射（XRD）、x射线荧光（XRF）、原子吸收光谱（AAS）和地球化学风化指标等技术分析了红粘土的矿物学、化学和重金属特征。粒度分布表明，受成土作用和风化作用的影响，土壤主要由细粒粉砂组成（约80%），含有少量粘土和砂。矿物学分析显示，石英、高岭石、伊利石、绿泥石和氧化铁占主导地位，表明在潮湿、寒冷的更新世气候下，风化变质岩和沉积岩混合在一起，风化强烈。地球化学数据显示SiO2含量高，矿物学成分成熟，属石英富源岩。主成分分析（PCA）指出了广泛的风化作用，特别是基性岩石。化学蚀变指数（CIA）值介于70.93% ~ 90.80%之间，为中度至强烈风化。微量金属浓度低于大陆上地壳平均水平，表明风化作用长期存在。这些发现强调了潮湿、寒冷的气候和构造环境在塑造孟加拉盆地更新世景观中的作用。该研究推进了区域古气候重建，强调了喜马拉雅侵蚀、河流运输和化学风化在形成独特的红粘土土中的相互作用。未来的工作应结合同位素示踪来完善沉积物来源分配和气候模式。

{"title":"Mineralogy and provenance of red clay soils in Barind and Madhupur clay formations, Bangladesh: Implications for tectonic setting and chemical weathering","authors":"Md.Golam Mostafa , Md.Aminur Rahman , Pradip Kumar Biswas , Abu Reza Md. Towfiqul Islam , Md.Ripaj Uddin , Hayatullah , Md.Nakib Hossen , Md. Nuruzzaman , Abu Yousuf , Md. Hasnain Mustak , Md. Shohel Rana","doi":"10.1016/j.jaesx.2025.100200","DOIUrl":"10.1016/j.jaesx.2025.100200","url":null,"abstract":"<div><div>This study investigates the geochemical and mineralogical properties of the Barind and Madhupur clay formations in the Bengal Basin, focusing on their provenance, tectonic setting and weathering processes in relation to regional geological evolution. Several techniques such as particle size distribution, X-ray diffraction (XRD), X-ray fluorescence (XRF), atomic absorption spectrometry (AAS) and geochemical weathering indices were applied to analyze the mineralogical, chemical and heavy metal characteristics of red clay soils. The particle size distribution reveals that the soil consists predominantly of fine-grained silt (∼80 %), with minor amounts of clay and sand, influenced by pedogenesis and weathering processes. Mineralogical analysis reveals dominance of quartz, kaolinite, illite, chlorite and iron oxides, suggesting a mix of weathered metamorphic and sedimentary rocks and intense weathering in a humid, cold Pleistocene climate. Geochemical data show high concentrations of SiO<sub>2</sub>, indicating a quartz-rich source with a mature mineralogical composition. Principal component analysis (PCA) points to extensive weathering, particularly of mafic rocks. Chemical index of alteration (CIA) values ranges from 70.93 % to 90.80 %, indicating moderate to intense weathering. Trace metal concentrations are lower than the average Upper Continental Crust, suggesting long-term weathering. These findings underscore the role of humid, cold climates and tectonic setting in shaping the Bengal Basin’s Pleistocene landscapes. The study advances regional paleoclimatic reconstructions and highlights the interplay of Himalayan erosion, fluvial transport and chemical weathering in producing the distinctive red clay soils. Future work should integrate isotopic tracing to refine sediment source apportionment and climatic models.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100200"},"PeriodicalIF":1.7,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144364786","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}

引用次数: 0

Changes in crater lake chemistry after the 2021 eruption at Aso Volcano, Japan: insights from UAV-based hot water sampling 2021年日本麻生火山喷发后火山口湖化学的变化：来自无人机热水采样的见解

IF 2.3 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences: X

Pub Date : 2025-12-01 Epub Date: 2025-11-23 DOI: 10.1016/j.jaesx.2025.100211

Hitomi Nakamura , Akihiko Yokoo , Hikaru Iwamori , Tatsuji Nishizawa , Masaaki Takahashi , Noritoshi Morikawa

Several volcanoes in Japan have summit craters filled with water, including Zao, Kusatsu-Shirane, Kirishima, and Aso volcanoes. Aso Volcano, located in central Kyushu, is an active caldera volcano with a crater lake whose water volume varies from nearly zero to full capacity depending on volcanic activity. Following the latest eruption of Aso Volcano in October 2021, we conducted UAV-based hot water sampling at the Nakadake First Crater (NFC) in 2022, 2023, and 2024. These efforts enabled the development of sampling method using a weight, rope, and sterilized sampling bottle with a long fluorinated ethylene propylene (FEP) sleeve, allowing hot water collection at temperatures higher than previously possible. We found that crater lake chemistry changed drastically within one year, with sulfate concentrations decreasing rapidly from 211,900 ppm in 2022 to 19,940 ppm in 2023 (approximately one-tenth), while temperature changes were smaller (about 5 °C). Compared with intermittent records from 1993 to 2009, these sulfate values were up to twice as high as previously reported maxima. Such deviations suggest increased inputs of magma-derived fluids, possibly associated with the 2021 eruption. Based on compiled data, we propose that extremely high chlorine concentrations in lake water can serve as significant indicators for predicting forthcoming eruptions, regardless of temperature changes. Our findings indicate that short-interval monitoring of the NFC is necessary to understand the transition between open and closed hydrothermal systems, especially after eruptions. Combined with UAV-based methods capable of sampling during eruptions, this approach will enhance understanding of crater lake hydrothermal dynamics and eruption forecasting.

日本的几座火山的山顶都有充满水的火山口，包括早灶火山、草津shirane火山、雾岛火山和麻生火山。阿索火山位于九州中部，是一座活火山，火山口湖的水量根据火山活动从几乎为零到满负荷变化。在2021年10月麻生火山最近一次喷发之后，我们于2022年、2023年和2024年在中泷第一火山口（NFC）进行了无人机热水取样。这些努力使取样方法得以发展，该方法使用砝码、绳子和带有长氟化乙丙烯（FEP）套管的灭菌取样瓶，可以在比以前更高的温度下收集热水。我们发现火山口湖的化学成分在一年内发生了巨大变化，硫酸盐浓度从2022年的211,900 ppm迅速下降到2023年的19,940 ppm（约十分之一），而温度变化较小（约5°C）。与1993年至2009年的间歇性记录相比，这些硫酸盐值高达先前报道的最大值的两倍。这种偏差表明岩浆衍生流体的输入增加，可能与2021年的喷发有关。根据汇编的数据，我们提出，无论温度如何变化，湖水中极高的氯浓度都可以作为预测即将爆发的重要指标。我们的研究结果表明，短间隔监测NFC是必要的，以了解开放和封闭的热液系统之间的过渡，特别是在喷发之后。结合能够在喷发期间进行采样的基于无人机的方法，该方法将增强对火山口湖热液动力学和喷发预测的理解。

{"title":"Changes in crater lake chemistry after the 2021 eruption at Aso Volcano, Japan: insights from UAV-based hot water sampling","authors":"Hitomi Nakamura , Akihiko Yokoo , Hikaru Iwamori , Tatsuji Nishizawa , Masaaki Takahashi , Noritoshi Morikawa","doi":"10.1016/j.jaesx.2025.100211","DOIUrl":"10.1016/j.jaesx.2025.100211","url":null,"abstract":"<div><div>Several volcanoes in Japan have summit craters filled with water, including Zao, Kusatsu-Shirane, Kirishima, and Aso volcanoes. Aso Volcano, located in central Kyushu, is an active caldera volcano with a crater lake whose water volume varies from nearly zero to full capacity depending on volcanic activity. Following the latest eruption of Aso Volcano in October 2021, we conducted UAV-based hot water sampling at the Nakadake First Crater (NFC) in 2022, 2023, and 2024. These efforts enabled the development of sampling method using a weight, rope, and sterilized sampling bottle with a long fluorinated ethylene propylene (FEP) sleeve, allowing hot water collection at temperatures higher than previously possible. We found that crater lake chemistry changed drastically within one year, with sulfate concentrations decreasing rapidly from 211,900 ppm in 2022 to 19,940 ppm in 2023 (approximately one-tenth), while temperature changes were smaller (about 5 °C). Compared with intermittent records from 1993 to 2009, these sulfate values were up to twice as high as previously reported maxima. Such deviations suggest increased inputs of magma-derived fluids, possibly associated with the 2021 eruption. Based on compiled data, we propose that extremely high chlorine concentrations in lake water can serve as significant indicators for predicting forthcoming eruptions, regardless of temperature changes. Our findings indicate that short-interval monitoring of the NFC is necessary to understand the transition between open and closed hydrothermal systems, especially after eruptions. Combined with UAV-based methods capable of sampling during eruptions, this approach will enhance understanding of crater lake hydrothermal dynamics and eruption forecasting.</div></div>","PeriodicalId":37149,"journal":{"name":"Journal of Asian Earth Sciences: X","volume":"14 ","pages":"Article 100211"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681157","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}

引用次数: 0