Geosystems and Geoenvironment最新文献

Integrating satellite observations, coral Sr/Ca proxies, and model simulations to analyze sea surface temperature variability (1915-2003) in Indonesia 综合卫星观测、珊瑚Sr/Ca代用物和模式模拟分析印度尼西亚的海面温度变化（1915-2003）

Geosystems and Geoenvironment

Pub Date : 2025-11-20 DOI: 10.1016/j.geogeo.2025.100481

Adinda Maharani , Rima Rachmayani , Adnya P.P. Pratiwi , Zulfikar Kartadimaja , Mutiara R. Putri , Ivonne M. Radjawane , Susanna Nurdjaman , Lamona I. Bernawis , Suliskania Nurfitri

Coral reefs are vital indicators of past oceanic conditions due to their ability to record environmental changes in their calcium carbonate structures. Specifically, the strontium-to-calcium ratio (Sr/Ca) in coral skeletons serves as a reliable proxy for reconstructing SST over time. The purpose of this study is to evaluate the similarity between sea surface temperature (SST) variability simulated by climate models and actual observations. The study utilized a comprehensive dataset that integrates satellite-derived SST observations and Coupled Model Intercomparison Project Phase 5 (CMIP5) model simulations with coral Sr/Ca records from three locations in Indonesia: Gili Selang, Kupang, and Nusa Penida. Based on the result, CCSM4 is the model with high robustness for simulation the sea surface temperature variability in Indonesia. CCSM4 has a higher correlation than other models when comparing data SST with OISST satellite and Sr/Ca record, whose correlation values are 0.7 and 0.32. The phases of ENSO and IOD exhibit a weak relationship with sea surface temperature (SST) distribution in the Indonesian region, as indicated by the low correlation values in the spatial correlation maps with CCSM4. These low correlation values suggest that the ENSO and IOD phenomena have a minimal impact on SST variability over Indonesia, as simulated by the CCSM4 model. The correlation coefficients between CCSM4 SST and the Niño index and Dipole Mode Index (DMI) during the two periods range from -0.213 to 0.055. Moreover, CCSM4 often simulates SST responses that are opposite to the expected effects of ENSO and IOD phases. These results indicate that, despite its relative strength among CMIP5 models, CCSM4 still lacks sufficient accuracy in reproducing the regional impacts of ENSO and IOD on SST variability in the Indonesian seas.

珊瑚礁是过去海洋状况的重要指标，因为它们能够记录碳酸钙结构的环境变化。具体来说，珊瑚骨骼中的锶钙比（Sr/Ca）可以作为重建海温随时间变化的可靠代理。本研究的目的是评估气候模式模拟的海温（SST）变率与实际观测的相似性。该研究利用了一个综合数据集，该数据集整合了卫星衍生的海温观测和耦合模式比对项目第5阶段（CMIP5）模式模拟，以及印度尼西亚三个地点（Gili Selang， Kupang和Nusa Penida）的珊瑚Sr/Ca记录。结果表明，CCSM4模式对印度尼西亚海温变化具有较高的鲁棒性。CCSM4与OISST卫星和Sr/Ca记录的海温数据的相关性高于其他模式，相关值分别为0.7和0.32。与CCSM4的空间相关图显示，印尼地区ENSO和IOD的相位与海温（SST）分布的相关性较弱。这些低相关值表明，正如CCSM4模式模拟的那样，ENSO和IOD现象对印度尼西亚海温变率的影响很小。CCSM4海温与Niño指数和偶极子模式指数（DMI）的相关系数在-0.213 ~ 0.055之间。此外，CCSM4经常模拟与ENSO和IOD相的预期效应相反的海温响应。这些结果表明，尽管CCSM4在CMIP5模式中相对较强，但在再现ENSO和IOD对印度尼西亚海海温变率的区域影响方面仍然缺乏足够的精度。

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引用次数: 0

Advanced machine learning based gold prospectivity mapping in the Dharwar Craton, India: A hybrid knowledge-data driven paradigm integrating ensemble and deep learning 印度Dharwar克拉通基于先进机器学习的金矿远景映射：集成集成和深度学习的混合知识数据驱动范式

Geosystems and Geoenvironment

Pub Date : 2025-11-07 DOI: 10.1016/j.geogeo.2025.100473

Soumya Mitra , Saptarshi Mallick , Santu Biswas , Kshounish Patra

Developing more sophisticated as well as efficient exploration methods to identify the hidden ore bodies are necessary to meet the world wide increasing demand of mineral resources. In this regard, mineral prospectivity mapping (MPM) is crucial. This study undertakes a pioneering effort to apply and compare four machine learning (ML) models—random forest (RF), XGBoost (XGB), support vector classifier (SVC) and artificial neural network (ANN)—for gold prospectivity mapping within the Archean Dharwar Craton, India. The primary goals included the development and evaluation of these models, a systematic assessment of their comparative performance through cross-validation, feature important analysis and ultimately, production of prospectivity map. The culmination of this work is a high-resolution, combined prospectivity map, designed to produce a new prospectivity areas. Diverse geospatial data was meticulously integrated as per mineral system of the area, including geological maps, structural lineaments, geochemical, geophysical and ASTER remote sensing imagery. For model training, 79 known gold occurrences were carefully collected alongside an equal number of selected non-occurrence locations, framing the task as a supervised binary classification problem. Rigorous evaluation, employing 5-fold cross-validation and a 70:30 train-test split, confirmed the exceptional capabilities of these models. XGB and RF consistently emerged as top performers, with impressive AUC-ROC values of 0.9992 and 0.9965, respectively, coupled with high precision, recall and F1-scores and few false positives or negatives. While ANN also showed excellent performance, SVC, though strong, yielded comparatively lower metrics. A detailed feature importance analysis exhibits the positive role of Meta-Basalt, geochemical principal component 1 and Bouguer gravity anomaly and its derivative maps. Success-rate curves vividly illustrated the models' efficiency capturing over 76% of known occurrences within just 20% of the highest-ranked areas shows targeting precision. The generated combined prospectivity map, a robust synthesis from XGB, RF and ANN, based on a stringent consensus criterion validates existing knowledge and precisely delineates high-priority exploration targets, fundamentally reshaping the approach to future mineral exploration.

为了满足世界范围内对矿产资源日益增长的需求，必须开发更先进、更有效的找矿方法来识别隐伏矿体。在这方面，矿产远景测绘（MPM）至关重要。本研究开创性地应用和比较了四种机器学习（ML）模型——随机森林（RF）、XGBoost （XGB）、支持向量分类器（SVC）和人工神经网络（ANN）——用于印度太古代Dharwar克拉通的金矿远景映射。主要目标包括开发和评估这些模型，通过交叉验证对其比较性能进行系统评估，特征重要分析并最终生成前景图。这项工作的最终成果是一张高分辨率的综合远景图，旨在产生一个新的远景区。根据矿区的矿产系统，对包括地质图、构造地貌、地球化学、地球物理和ASTER遥感影像在内的多种地理空间数据进行了精心整合。对于模型训练，我们仔细收集了79个已知的金矿点，以及相同数量的选定的非金矿点，将该任务构建为一个监督二元分类问题。严格的评估，采用5倍交叉验证和70:30训练测试分割，证实了这些模型的卓越能力。XGB和RF一直是表现最好的，AUC-ROC值分别为0.9992和0.9965，加上高精度、召回率和f1得分高，假阳性或阴性少。虽然人工神经网络也表现出出色的性能，但SVC虽然很强，但产生的指标相对较低。详细的特征重要性分析表明，变质玄武岩、地球化学主成分1和布格重力异常及其衍生图在该区的积极作用。成功率曲线生动地说明了模型的效率，在排名最高的20%的区域内捕获了超过76%的已知事件，显示了目标精度。生成的组合远景图是XGB、RF和ANN的强大综合，基于严格的共识标准，验证了现有知识，并精确地划定了高优先级的勘探目标，从根本上重塑了未来矿产勘探的方法。

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引用次数: 0

Analysis of the trend of dry spells and how ocean factors affect their patterns during the summer monsoon in Bangladesh using the Mann-Kendall and frontier atmospheric general circulation model 利用Mann-Kendall和前沿大气环流模式分析孟加拉国夏季风期间干旱的趋势和海洋因素如何影响其模式

Geosystems and Geoenvironment

Pub Date : 2025-11-07 DOI: 10.1016/j.geogeo.2025.100472

Md. Moniruzzaman Monir , Subaran Chandra Sarker , Md. Mostafizur Rahman , Md. Nazrul Islam

To assess drought risk, susceptibility to food security, and water resource utilization, it is crucial to comprehend dry spell patterns from a hydrological perspective. Some regional studies have noted an extension of dry spells on a global and regional scale, but it is still unclear how often dry spells occur during the summer monsoon season, which is dominated by rainfall. This study uses the Mann-Kendall trend test to examine the trend of dry spells during Bangladesh's summer monsoon from 1985 to 2022 to close this gap. Using the frontier atmospheric general circulation model and remote sensing methods to examine the effects of ocean elements such as Indian Ocean Dipole (IOD), sea surface temperature (SST), El Niño-southern oscillation (ENSO) conditions, and the zonal wind. Daily rainfall data for 34 weather stations were obtained from the Bangladesh Meteorological Department, while surface water occurrence and change intensity data were retrieved from the JRC Global Surface Water Mapping Layers, v1.3 (FAO, UN). The NOAA Physical Sciences Laboratory (PSL) and the Tokyo Climate Center/WMO Regional Climate Centre in RA II (Asia) provided the IOD, SST, ENSO, and zonal wind data. A notable dry spell anomaly over Bangladesh was also observed in this research, with short, medium-length, and long dry spells increasing at 82.35 %, 73.53 %, and 50 % of the weather stations, respectively. Dry spells become less frequent during El Niño but more during La Niña. The climatic variability of IOD events and SST anomalies in the eastern and western tropical Indian Ocean was also noted by this study to be connected to these anomalous events. The correlation coefficient between summer monsoon rainfall and DMI is 0.34. Throughout the study period, there were changes in the upper atmosphere's and lower troposphere's wind circulation. The study allows the prioritization of regions for drought, effective water resource management, and food scarcity preparedness.

为了评估干旱风险、粮食安全易感性和水资源利用，从水文角度理解干旱模式至关重要。一些区域性研究指出，干旱期在全球和区域范围内都在延长，但尚不清楚干旱期在以降雨为主的夏季季风季节发生的频率。本研究使用Mann-Kendall趋势检验来检验1985年至2022年孟加拉国夏季季风干旱期的趋势，以缩小这一差距。利用前沿大气环流模式和遥感方法研究印度洋偶极子（IOD）、海表温度（SST）、El Niño-southern涛动（ENSO）条件和纬向风等海洋要素的影响。34个气象站的日降雨量数据来自孟加拉国气象局，地表水发生和变化强度数据来自JRC全球地表水制图层，v1.3 （FAO， UN）。NOAA物理科学实验室（PSL）和东京气候中心/WMO亚洲区域气候中心提供了IOD、SST、ENSO和纬向风资料。本研究还观察到孟加拉国上空明显的干旱异常，气象站的短、中、长干旱分别增加了82.35%、73.53%和50%。干旱在El Niño期间变得不那么频繁，但在La Niña期间更加频繁。热带印度洋东、西部海温异常和IOD事件的气候变率也与这些异常事件有关。夏季风降水与DMI的相关系数为0.34。在整个研究期间，高层大气和低层对流层的风环流都发生了变化。这项研究有助于确定干旱地区的优先次序、有效的水资源管理和粮食短缺防范。

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引用次数: 0

Identification of structurally controlled potential mineralization zones in Chhotanagpur Gneissic Complex, Eastern India from gravity and magnetic data 印度东部Chhotanagpur片麻岩杂岩重磁资料识别构造控制的潜在成矿带

Geosystems and Geoenvironment

Pub Date : 2025-11-04 DOI: 10.1016/j.geogeo.2025.100470

Afaque Karim , Anurag Tripathi , Upananda Low , Mohd Tabish Ansari , Deepak Yadav , Kashi Nath Prasad

The present study delineates zones of potential mineralization within the Chhotanagpur Gneissic Complex (CGC) using integrated geophysical methods. Comprehensive gravity and magnetic surveys were conducted across ∼3500 km² revealing seven high–priority blocks characterized by distinct Bouguer gravity anomalies (–46 to –19 mGal) and magnetic intensity variations (–246 to +710 nT). These geophysical anomalies are linked to surface lithologies like mica–schist belts, amphibolites and intrusive bodies which are indicative of economically significant mineral deposits. In this study, structural analysis highlights NE–SW and NW–SE trending lineaments and faults that may play a key control on mineralization in the area. Depth estimations from radially averaged power spectrum (RAPS) and Euler 3D solutions shows causative bodies are deeper (∼4 km) in western region than the eastern region (∼1–2 km). The integration of geophysical data with geological interpretations enhances understanding of the CGC in the context of possible influence on mineralization processes. The present findings provide a strategic pathway for guiding further mineral exploration initiatives in seven potential zones identified in the study area.

本文利用综合地球物理方法圈定了Chhotanagpur片麻岩杂岩（CGC）的潜在成矿带。在约3500 km²的范围内进行了全面的重磁调查，揭示了7个高优先级区块，其特征是明显的布格重力异常（-46至-19 mGal）和磁场强度变化（-246至+710 nT）。这些地球物理异常与表面岩性有关，如云母片岩带、角闪岩和侵入体等，表明具有经济意义的矿床。构造分析强调了NE-SW和NW-SE走向的构造和断裂可能对该区成矿作用起关键控制作用。根据径向平均功率谱（RAPS）和欧拉三维解估算的深度显示，西部地区的致病体深度（~ 4公里）比东部地区深（~ 1-2公里）。地球物理资料与地质解释的结合增强了对CGC对成矿过程可能影响的认识。目前的研究结果为指导研究区内确定的七个潜在带的进一步矿产勘探活动提供了战略途径。

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引用次数: 0

Stage of the vein series formation processes of the Burpala massif (North Baikal), according to chemical microprobe Th-U-Pb dating of monazites 北贝加尔湖Burpala地块脉系形成过程的阶段——单氮石化学探针Th-U-Pb测年

Geosystems and Geoenvironment

Pub Date : 2025-11-01 DOI: 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.

研究了布尔帕拉地块2个含矿伟晶岩带（西伟晶岩带和英立岩带）单氮石的标型特征和年龄。这使得澄清侵入岩脉相的形成阶段成为可能。还获得了有关单独居石与造岩和矿石矿物关系的资料。采用CHIME方法计算了稀土伟晶岩中独居石的Th-U-Pb等时年龄：287±54 Ma（西部带）和273±69 Ma（不列颠岩带）。得到的布尔帕拉地块稀有金属伟晶岩年龄值与已有的地质、年代学资料吻合较好，表明其存在多个形成阶段，补充了脉状杂岩的岩浆作用方案（麻乌长岩→富雅岩→西带稀有金属伟晶岩→英透岩带稀有金属伟晶岩→磷灰石-荧光岩→碳酸盐岩→阿拉斯岩和碱性花岗岩）。两个伟晶岩带的独居石年龄与布尔帕拉地块西北带的主相和稀有金属伟晶岩的形成时间接近，属于安加拉-维提姆基北架晚古生代板内岩浆活动的一般阶段。

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引用次数: 0

Geochemistry and petrology of deep seated mantle magmas and their mantle xenoliths and xenocrysts: Applications to the structure and compositions of mantle lithosphere 深部地幔岩浆及其幔包体和幔包体的地球化学和岩石学：在地幔岩石圈结构和组成中的应用

Geosystems and Geoenvironment

Pub Date : 2025-11-01 DOI: 10.1016/j.geogeo.2025.100388

Igor V. Ashchepkov , N.V. Chalapathi Rao , Rohit Pandey , Sergei V. Rasskazov

引用次数: 0

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 印度中部构造带贝图尔带帕达尔基性-超基性元古代弧岩浆活动：岩石学、大块岩石和原位微量元素地球化学的启示

Geosystems and Geoenvironment

Pub Date : 2025-11-01 DOI: 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.

本研究首次在位于中印度构造带（CITZ）的晚元古代Padhar基性-超基性杂岩（PMUC）中发现了阿拉斯加型侵入岩。侵入体的组成有差异，包括橄榄岩、辉石岩、角闪辉长岩和闪长岩。我们采用综合方法，将实地研究与主要氧化物、原位微量元素和稀土元素地球化学分析相结合。PMUC的野外证据呈同心分带状，其核部为白云石、橄榄石斜辉石岩、斜辉石岩、角闪石斜辉石岩和辉长岩，与阿拉斯加型侵入体相似。PMUC中的主要矿物包括橄榄石（橄榄石）、辉石（Cpx和Opx）、角闪洞、云母、铬铁矿和磁铁矿，而次生矿物如蛇纹石、绿泥石和滑石也存在。橄榄石（70-77）、正辉石（53-73）和斜辉石（67-88）镁质数（Mg#）从基性单元到超基性单元的增加表明它们与同一母质熔体有分化。地球化学特征为Nb、Zr负异常和Rb正异常，表明该区有板块沉积流体交代作用。从早期橄榄石的镁值和高角闪孔含量推断出含水母岩浆的存在。辉石和角闪孔矿物的构造判别图，结合原位微量元素化学和块状岩石地球化学，表明其成因与弧有关。研究结果表明，该区存在流体驱动的俯冲带交代作用，具有元古代阿拉斯加型构造的特征。铂族元素地球化学特征显示出较高的(Pt + Pd)/(Ir + Ru)比值，与阿拉斯加型侵入岩相似。地质和地球化学数据进一步支持PMUC代表了元古宙弧的一个浅层（约17公里）段，在Betul带中，较小的超镁铁质单元充当了弧岩浆的管道。

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引用次数: 0

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 来自西萨哈林岛（俄罗斯远东）的非俯冲伊卡拉埃达岩类岩石与来自日本西南部的超俯冲Daisen埃达岩：来自源的微量元素模拟的见解

Geosystems and Geoenvironment

Pub Date : 2025-11-01 DOI: 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.

伊查拉杂岩体位于西萨哈林岛晚新生代Orlov火山带上，位于拉玛农角地区。伊查拉杂岩和Orlov火山田的安山岩和英安岩表现出高Sr/Y、低ree和Y、高La/Yb的类埃达岩特征，与壳幔过渡时期岩浆生成有关。微量元素部分熔融模拟表明，阿达岩类岩石的来源为原始地幔，混合了下地壳成分（7 - 12%）和少量流体成分（0.5 - 1%）。模式物源中石榴石和角闪洞含量及部分熔融程度从奥尔洛夫火山田较老的埃达岩型安山岩向伊卡拉杂岩较年轻的安山岩和英安岩增加。西库页岛阿达岩安山岩向英安岩的87Sr/86Sr值减小，Sr/Y值增大，对应于下地壳和超俯冲流体组分的作用增强。最明显的埃达岩类特征是来自斜辉石-角闪石-石榴石源的英安岩特征，具有最大的下地壳添加。在模拟源中没有检测到年轻板（morb型）材料。与伊卡拉埃达克岩类岩石相比，本州西南部的Daisen埃达克岩模型提供了菲律宾海板块上部熔融的证据，其中超俯冲流体成分的贡献很大。

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引用次数: 0

Interpretation of gravity-seismic joint inversion and its application in Longmenshan region 重震联合反演解释及其在龙门山地区的应用

Geosystems and Geoenvironment

Pub Date : 2025-10-25 DOI: 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.

分析和研究破坏性地震前后的大型复杂现象，对减少自然灾害的威胁具有重要意义。了解龙门山断裂带的复杂构造变形对阐明地壳变形和地震动力机制具有重要意义。本文分析了汶川地震带重力异常分布特征，并应用边缘检测方法反演了龙门山地区的震前重力异常。确定了龙门山及其邻区震前断层的分布特征。通过地震前后重力异常剖面的欧拉反褶积结果，分析了地震形态差异和可能的地震成因。最后，基于已有地震和重力资料进行二维交互联合反演。通过对比地震前后的地下变化，揭示了地震的地下构造，探讨了地震的形成机制。

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引用次数: 0

Contribution of the geoelectric method to the identification of geological formations in the Ngaoundal locality (Adamawa, Cameroon) 地电方法在Ngaoundal地区（喀麦隆Adamawa）地质构造识别中的贡献

Geosystems and Geoenvironment

Pub Date : 2025-10-25 DOI: 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.

这项研究强调了地电对Ngaoundal地区地质构造特征的贡献。使用斯伦贝谢的设备进行了29.9平方公里的电测绘，在一个完全被花岗岩基岩上发育的土壤覆盖的区域，以700米的间隔进行了51次垂直电测深（VES）。在AB/2 = 1.5 ~ 100 m的深度范围内，视电阻率图显示了低、中、高电阻率范围。根据测深和电阻率划分了10种主要的测深曲线类型（Q、HK、KH、H、KQ、QH、HKH、K、KQH和QHK）。电阻率图和电测深曲线综合分析表明，地表以红土土为主，中深为砂粘土土，深部为裂隙或健全基岩。4条伪电阻率剖面显示弱异常（ρ < 350 Ω·m）、中异常（350≤ρ≤1800 Ω·m）和强异常（ρ≥1800 Ω·m），分别对应于松散风化层（风化花岗岩、砾质土）、裂隙花岗岩和形成基岩的岩体。红土层厚度图划分为低（1.33 ~ 2.58 m）、中（2.59 ~ 2.84 m）、高（2.85 ~ 8.94 m） 3个等级。与现有钻孔资料对比，证实了地球物理模型的一致性。地球物理方法和直接钻孔观测之间的这种互补性加强了该方法的可靠性，并为Ngaoundal地区地下地质和水文地质解释提供了一个强大的框架。

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