Geosystems and Geoenvironment最新文献_第9页

Biostratigraphy, stratigraphy and paleoenvironments of middle Eocene – middle Oligocene sediments from Onshore Niger Delta, Nigeria: Insights from foraminifera and palynomorphs 尼日利亚尼日尔三角洲中始新世-中渐新世沉积物的生物地层学、地层学和古环境：来自有孔虫和岩形虫的启示

Geosystems and Geoenvironment

Pub Date : 2025-08-01 Epub Date: 2025-04-10 DOI: 10.1016/j.geogeo.2025.100391

Moshood Adegboyega Olayiwola , Olugbenga Temitope Fajemila

In recent times, biostratigraphy, apart from its primary roles in age dating, paleoenvironmental reconstruction and correlation now constitutes a significant aspect of sequence stratigraphy applicable in exploration and production activities. Unfortunately, published biostratigraphic and biochronostratigraphic records of Niger Delta Eocene –Oligocene sediments are scanty. This integrated study of the H1-P well (1250–3931 m) from the Central Niger Delta revealed two lithostratigraphic units, the continental Benin Formation (1250–2384 m) and the Upper Agbada Formation (2384–3931 m) composed of alternating sand and shale intervals. The uppermost section (1250–2384 m), which is within the continental Benin Formation was barren of foraminifera. However, it was dated Early to Middle Oligocene (P520-P560) based on diagnostic palynomorphs. Conversely, the lowermost part (3931–2384 m), consisting moderate numbers of foraminifera species, was dated Late Eocene (P480). The paleoenvironments, which fluctuated between Coastal Deltaic to Middle Neritic, were subdivided into four highstand and four transgressive systems tracts. The 39.4 Ma, 38.0Ma, 36.8 Ma and 35.9 Ma maximum flooding surfaces, and three sequence boundaries were inferred. The youngest maximum flooding surface dated 35.9 Ma at 2385 m, was defined by the FDO Nonion oyae, FDO Brizalina ihuoensis (2402 m), presence of Globigerina yeguaensis and FDO Uvigerinella sparsicostata at 2713 m, the FDO of the diagnostic palynomorphs Grimsdalea polygonalis, Doualaidites laevigatus, at 2414 m / 2792 m respectively indicated the penetration of Late Eocene. The FDO Uvigerina hourqi delineated the Middle/Late Eocene boundary at 3121 m. The Middle Eocene is further characterized by Acme Uvigerinella sparsicostata and occurrence of Chiloguembelina martini. The sequence stratigraphic interpretation permitted age dating of the maximum flooding surfaces and the sequence boundaries within the well section.

近年来，生物地层学除了在年代测年、古环境重建和对比等方面的主要作用外，已成为层序地层学的一个重要方面，可应用于勘探和生产活动。不幸的是，尼日尔三角洲始新世-渐新世沉积物的生物地层学和生物年代学记录很少。通过对中尼日尔三角洲H1-P井（1250-3931 m）的综合研究，发现了两个岩性地层单元，即大陆Benin组（1250-2384 m）和上Agbada组（2384-3931 m），这两个地层单元由砂页岩层段交替组成。最上层（1250-2384米）位于贝宁组大陆区内，没有有孔虫。然而，根据诊断特征，它的年代为早至中渐新世（P520-P560）。相反，最下层（3931-2384 m）有孔虫种类数量适中，年代为晚始新世（P480）。古环境在滨海三角洲与中浅海沉积之间波动，划分为4个高地体系域和4个海侵体系域。推断出39.4 Ma、38.0Ma、36.8 Ma和35.9 Ma的最大洪水面和3个层序边界。在2385 m处，FDO Nonion oyae、FDO Brizalina ihuoensis （2402 m）、gloigerina yeguaensis和Uvigerinella sparsicostata （2713 m）、Grimsdalea polygonalis、Doualaidites laevigatus在2414 m和2792 m处的FDO分别显示了晚始新世的渗透。FDO Uvigerina hourqi在3121 m处圈定了中、晚始新世界线。中始新世的进一步特征是Uvigerinella sparsicostata尖顶菌和Chiloguembelina martini的出现。层序地层解释允许在井段内确定最大淹水面和层序边界的年龄。

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引用次数: 0

Petrogenesis and tectonic implications of Early Cretaceous I-type granites from offshore drilling in east of the Fuzhou City, Southeast China 福州市东部早白垩世海上钻探ⅰ型花岗岩成因及其构造意义

Geosystems and Geoenvironment

Pub Date : 2025-08-01 Epub Date: 2025-04-27 DOI: 10.1016/j.geogeo.2025.100400

Han Yan , Xi-Yao Li , Xun Yuan , Sanzhong Li , Xin Chen , Pengcheng Wang , Yu Wang , Jie Gao

The Cretaceous (<115 Ma) granitoid rocks in Southeast China provide critical insights into the role of juvenile materials in their genesis, as evidenced by the presence of I- and A-type granites. This study presents comprehensive geochronological, mineralogical, geochemical, and Sr–Nd–Hf isotopic data for granites collected from the offshore drilling in the western East China Sea, located east of the Fuzhou City (Fujian Province), Southeast China. Zircon, apatite, and titanite U–Pb dating reveal that the granite samples formed at 112–111 Ma. The samples exhibit geochemical characteristics typical of I-type granites, with negative whole-rock ε_Nd(t) values (–4.4) and zircon ε_Hf(t) values ranging from –2.8 to 0.1. These I-type granites were primarily formed through partial melting of mafic igneous protoliths, followed by magma mixing with ancient crustal materials. We propose that the SE China coast underwent a transition from a compressional to a lithospheric extensional environment during the late Early Cretaceous, driven by the slab rollback of the subducted Paleo-Pacific Plate. This lithospheric extension facilitated the underplating of mantle-derived magma, which modified the crustal source and induced melting of continental arc crustal materials.

中国东南部白垩系（<115 Ma）花岗质岩石的I型和a型花岗岩的存在，为研究其成因提供了重要的线索。本文介绍了中国东南部福建省福州市东部东海西部海上钻探花岗岩的年代学、矿物学、地球化学和Sr-Nd-Hf同位素的综合数据。锆石、磷灰石和钛矿U-Pb测年结果表明，花岗岩样品形成于112 ~ 111 Ma。样品具有典型的i型花岗岩地球化学特征，全岩εNd(t)值为负（-4.4），锆石εHf(t)值在-2.8 ~ 0.1之间。这些i型花岗岩主要是由基性火成岩原岩部分熔融形成的，然后是岩浆与古地壳物质混合形成的。我们认为，早白垩世晚期，在古太平洋板块俯冲的板块回滚作用下，中国东南海岸经历了由挤压环境向岩石圈伸展环境的转变。这种岩石圈的伸展促进了幔源岩浆的下镀，改变了地壳的来源，诱发了大陆弧地壳物质的熔融。

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引用次数: 0

Schematic formation of boudine granite and microfold phyllite of Gilas River: Implications for Triassic to Tertiary tectonics of Garba Hill, South Ogan Komering Ulu Regency, South Sumatra Province 吉拉斯河波丁花岗岩和微褶皱千层岩的示意图：对南苏门答腊省南Ogan Komering Ulu地区Garba山三叠纪至第三纪构造的启示

Geosystems and Geoenvironment

Pub Date : 2025-08-01 Epub Date: 2025-05-28 DOI: 10.1016/j.geogeo.2025.100414

Idarwati , Budhi Setiawan , Stevanus Nalendra Jati , Yogie Zulkurnia Rochmana , Elisabet Dwi Mayasari , Muhammad Rendana

Gilas River is one of the areas that shows interesting geological structures due to the meeting between West Sumatra and the Woyla Block. This boudine and microfold formation scheme aims to reveal the tectonics of Sumatra Island during the Late Cretaceous to Tertiary period, especially those found in the Gilas River. The methods used are DEMNas (National Digital Elevation Model) analysis, outcrop observation, and deformation element data analysis. The data obtained is then used to reconstruct structural architecture models, force-related deformation mechanisms, and the tectonic evolution of the area. The Gilas Strip experienced several tectonic events based on the results of research at the observation site. Based on the results of the analysis, it is known that the first structure is a foliation in the phyllite rock which is oriented ESE-WNW due to the first deformation in the Triassic period. The second deformation occurred in the Late Cretaceous period which produced the NNE-SSW trending Dextral Milling Fault (S2). The formation of micro folds with the fold axis having a position of N118°E/80 found at observation location IWD 4 and boudine structure with ENE-WSW direction at observation location IWD 5 is the result of the second deformation (D2). The Gilas Right Horizontal Fault produces an antithetic fault in the form of a left horizontal fault with a relative direction of E-W (S2′). The last period is the formation of a conjugate shear fault at the observation location IWD 3 due to Neogene tectonic deformation (D3), with a relative N-S fault direction.

吉拉斯河是西苏门答腊和沃伊拉地块交汇而形成的有趣的地质构造区域之一。该微褶构造方案旨在揭示苏门答腊岛晚白垩世至第三纪的构造，特别是在吉拉斯河发现的构造。使用的方法是DEMNas（国家数字高程模型）分析、露头观测和变形元素数据分析。然后利用获得的数据重建构造建筑模型、与力有关的变形机制以及该地区的构造演化。根据观测地点的研究结果，吉拉斯带经历了几次构造事件。根据分析结果可知，第一个构造为三叠纪首次变形形成的千层岩中的一个面理构造，其方向为东南—西西北向。第二次变形发生在晚白垩世，形成了北北东—南南西走向的右旋磨裂（S2）。在观测位置IWD 4形成了褶皱轴线为N118°E/80的微褶皱，在观测位置IWD 5形成了ENE-WSW方向的boudine构造，这是第二次变形（D2）的结果。吉拉斯右水平断层形成一条相对方向为东西向（S2′）的左水平断层。最后一个阶段是新近系构造变形（D3）在观测位置IWD 3处形成一条共轭剪切断层，断层方向相对为N-S。

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引用次数: 0

Predicting urban landslides in the hilly regions of Bangladesh leveraging a hybrid machine learning model and CMIP6 climate projections 利用混合机器学习模型和CMIP6气候预测预测孟加拉国丘陵地区的城市山体滑坡

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-01-18 DOI: 10.1016/j.geogeo.2025.100354

Md․ Ashraful Islam , Musabbir Ahmed Arrafi , Mehedi Hasan Peas , Tanvir Hossain , Md Mehedi Hasan , Sanzida Murshed , Monira Jahan Tania

Landslides pose significant risks to infrastructure and human lives in cities, exacerbated by climate change. Therefore, a reliable predictive landslide model is crucial for mitigation, especially in resource-limited nations. This study employs hybrid machine learning (ML) techniques and climate projections to predict landslides in the Chattogram development area (CDA) of Bangladesh – a rapidly growing urban city in Bangladesh. The model was trained using diverse geospatial parameters including topographical, hydrological, soil, and geological parameters, along with an updated landslide inventory, enabling spatially explicit predictions of landslide susceptibility. To incorporate future climate scenarios, we utilized the Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Model (GCM), projecting climate impacts under SSP1-2.6 and SSP5-8.5 scenarios for the periods of 2021–2040, 2041–2060, 2061–2080, and 2081–2100, respectively. These scenarios reflect different pathways of greenhouse gas emissions, providing a range of possible future climate conditions. We tested six ML classifiers: random forest (RF), extra trees (ExT), support vector machine (SVM), logistic regression (LR), Bernoulli Naïve Bayes (bNB), and K-nearest neighbor (KNN). Each base model demonstrated high accuracy (>90 %) but combining them improved both accuracy and computational efficiency. The LR-bNB hybrid model outperformed all others, effectively mapping landslide susceptibility in the study area for the current timeframe and future projections. Our results revealed significant variability in landslide-prone areas across the area, with 12 % of the region categorized as high to very high risk, a figure that slightly rises with predicted increased rainfall due to climate change. The present study demonstrates the efficacy of a hybrid ML model for nowcasting as well as forecasting landslide susceptibility under future climate scenarios. These findings offer valuable insights for proactive risk management and infrastructure planning in the CDA, helping to safeguard communities and improve resilience against future landslide events.

山体滑坡对城市的基础设施和人类生命构成重大风险，而气候变化又加剧了这一风险。因此，一个可靠的滑坡预测模型对于减轻灾害至关重要，尤其是在资源有限的国家。本研究采用混合机器学习（ML）技术和气候预测来预测孟加拉国 Chattogram 发展区（CDA）的滑坡，该发展区是孟加拉国一个快速发展的城市。该模型使用多种地理空间参数（包括地形、水文、土壤和地质参数）以及更新的滑坡清单进行训练，从而能够在空间上明确预测滑坡的易发性。为纳入未来气候情景，我们利用耦合模式相互比较项目第 6 阶段（CMIP6）全球气候模式（GCM），分别预测了 2021-2040 年、2041-2060 年、2061-2080 年和 2081-2100 年期间 SSP1-2.6 和 SSP5-8.5 情景下的气候影响。这些情景反映了不同的温室气体排放路径，提供了一系列可能的未来气候条件。我们测试了六种 ML 分类器：随机森林 (RF)、额外树 (ExT)、支持向量机 (SVM)、逻辑回归 (LR)、伯努利奈夫贝叶斯 (bNB) 和 K 近邻 (KNN)。每个基本模型都表现出很高的准确率（90%），但将它们结合起来，准确率和计算效率都得到了提高。LR-bNB 混合模型的表现优于其他所有模型，能有效地绘制出研究区域当前时间框架和未来预测的滑坡易感性图。我们的研究结果表明，整个地区的滑坡易发区存在显著差异，其中 12% 的区域被归类为高风险或极高风险区域，随着气候变化导致的降雨量增加，这一数字将略有上升。本研究证明了混合 ML 模型在预测未来气候情景下的山体滑坡易发性方面的有效性。这些研究结果为中国加速发展区的前瞻性风险管理和基础设施规划提供了宝贵的见解，有助于保护社区和提高应对未来滑坡事件的能力。

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引用次数: 0

Assimilation of seismic attenuation model of NW Himalaya and its surrounding region 西北喜马拉雅及其周边地区地震衰减模式的同化

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-03-08 DOI: 10.1016/j.geogeo.2025.100378

Vandana, Naresh Kumar

In this study, we analyze the seismic attenuation characteristics of the Northwest Himalaya and adjacent regions using a dataset of 2,716 earthquakes (2.5 ≤ Mw ≤ 5.0) recorded from 2008 to 2015 by a network of 30 broadband seismographs. The single backscattering model was applied to estimate the quality factor of coda waves (Q_c) across three lapse time windows (LTWs) at varying frequencies. Our results reveal that Q_c increases with both frequency and LTW, suggesting a depth-dependent nature of seismic attenuation in the region. The average attenuation relationships for Q_c, Q_α and Q_β across the Northwest Himalaya are determined as follows for LTWs of 20, 30, and 40 s, respectively: Q_c = (74 ± 14)f ^(1.27±0.06), Q_c = (103 ± 26)f ^(1.16±0.08), and Q_c = (140 ± 41)f ^(1.10±0.09). Our findings reveal significant variability in Q_c, Q_α and Q_β across the Tethys (TH), High (HH), Lesser (LH), and Shiwalik (SH) Himalaya regions, as well as the adjacent Indo-Gangetic Plains (IGP), with this variability strongly linked to structural heterogeneity and seismogenic processes in each region. We further establish attenuation relations for distinct tectonic units, observing the following hierarchy: [Q_α,β,c⁻¹(HH) < Q_α,β,c⁻¹(SH) < Q_α,β,c⁻¹(IGP) < Q_α,β,c⁻¹(LH) < Q_α,β,c⁻¹(TH)]. The Tethys Himalaya exhibits the high attenuation, likely due to its sedimentary structure, while the Higher Himalaya shows the low attenuation. These insights into attenuation characteristics across geotectonic segments in the Northwest Himalaya contribute to a more comprehensive seismic hazard assessment for the region.

本文利用30台宽带地震仪在2008 - 2015年间记录的2716次地震（2.5≤Mw≤5.0）数据，分析了喜马拉雅西北部及邻近地区的地震衰减特征。采用单后向散射模型估计了不同频率下尾波在三个时间窗（LTWs）上的质量因子。我们的研究结果表明，Qc随频率和LTW的增加而增加，表明该地区地震衰减具有深度依赖性质。在20、30和40 s的ltw下，喜马拉雅西北地区Qc、Qα和Qβ的平均衰减关系分别为：Qc =(74±14)f（1.27±0.06）、Qc =(103±26)f（1.16±0.08）和Qc =(140±41)f（1.10±0.09）。我们的研究结果揭示了Qc、Qα和Qβ在Tethys （TH）、High （HH）、Lesser （LH）和Shiwalik （SH）喜马拉雅地区以及邻近的印度-恒河平原（IGP）的显著变化，这种变化与每个地区的结构非均质性和孕震过程密切相关。我们进一步建立了不同构造单元的衰减关系，观察到以下层次：[Qα，β,c−1(HH) <；问α,β,c−1 (SH) & lt;问α,β,c−1(显卡)& lt;问α,β,c−1 (LH) & lt;问α,β,c−1 (TH)]。特提斯-喜马拉雅的衰减程度较高，可能与沉积构造有关，而上喜马拉雅的衰减程度较低。这些对喜马拉雅西北部大地构造段衰减特征的了解有助于对该地区进行更全面的地震危险性评估。

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引用次数: 0

WebGIS-based decision support system for soil erosion risk assessment for Guder River catchment, Ethiopia 基于webgis的古德尔河流域土壤侵蚀风险评估决策支持系统

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-03-30 DOI: 10.1016/j.geogeo.2025.100387

Kedir Kemal Hajisheko , Karuturi Venkata Suryabhagavan , Karuturi Soumya

Soil erosion is a crucial environmental issue affecting agricultural productivity, water quality, and ecosystem sustainability. Deforestation and human activities have led to excessive soil erosion. A webGIS-based decision support system (DSS) was developed to provide complete information on soil erosion in the Guder watershed forming a part of the Abay River Basin in Ethiopia. The parameters employed were estimated using remote sensing data. Sub-watersheds were prioritised based on soil erosion risk through a revised universal soil loss equation (RUSLE) integrated with geographic information system (GIS). The study employed high-resolution spatial data, including rainfall, soil properties, and topography, to model erosion rates across the watershed. Results indicate that the annual soil loss in the watershed varied significantly from 0 to 8021 t ha⁻¹ yr⁻¹, with an average loss of 97.5 t ha⁻¹ yr⁻¹. About 33.3% of the watershed experienced very high soil loss (>50 t ha⁻¹ yr⁻¹), accounting for 91.3% of the total eroded. In contrast, 25.5% of the area exhibited medium soil erosion rates (<5 t ha⁻¹ yr⁻¹). The WebGIS tool developed is powerful and user-friendly portal that enables non-technical users to access real-time soil erosion data and better understand soil conservation programs, helping them identify measures to reduce soil erosion in the watershed. Moreover, this information also supports land managers, policymakers, and farmers in adopting targeted soil erosion control measures, promoting sustainable land management in the region.

土壤侵蚀是影响农业生产力、水质和生态系统可持续性的重要环境问题。森林砍伐和人类活动导致了过度的土壤侵蚀。开发了一个基于网络地理信息系统的决策支持系统（DSS），以提供关于构成埃塞俄比亚阿贝河流域一部分的古德流域土壤侵蚀的完整信息。所采用的参数是利用遥感数据估计的。通过与地理信息系统（GIS）相结合的修正通用土壤流失方程（RUSLE），基于土壤侵蚀风险对子流域进行优先排序。这项研究采用了高分辨率的空间数据，包括降雨、土壤性质和地形，来模拟整个流域的侵蚀率。结果表明，流域年土壤流失量在0 ~ 8021 tha−1 yr−1之间变化显著，平均流失量为97.5 tha−1 yr−1。约33.3%的流域土壤流失非常严重（50 t / h - 1年- 1年），占侵蚀总量的91.3%。相比之下，25.5%的地区表现出中等的土壤侵蚀率（<5(1 - 1)）。开发的WebGIS工具是一个功能强大且用户友好的门户，使非技术用户能够访问实时土壤侵蚀数据，更好地了解土壤保持计划，帮助他们确定减少流域土壤侵蚀的措施。此外，这些信息还有助于土地管理者、政策制定者和农民采取有针对性的水土流失控制措施，促进该地区的可持续土地管理。

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引用次数: 0

Tonian shoshonitic to ultrapotassic granitoids from Chhotanagpur Gneissic Complex, Eastern Indian Shield: Age, origin and tectonic implications 东印度盾区Chhotanagpur片麻岩杂岩中Tonian玄武岩-超古生代花岗岩：时代、成因及构造意义

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-02-28 DOI: 10.1016/j.geogeo.2025.100373

Ankita Basak , Bapi Goswami , Yoann Gréau , Susmita Das , Chittaranjan Bhattacharyya

This work reports petrogenesis of an ultrapotassic granitoid pluton emplaced in the Tonian (949.4 ± 2.3 Ma; new LA-ICPMS zircon U–Pb dating) along a regional shear zone during the post-collisional stage of the Grenvillian Satpura orogeny in Eastern India. The hypidiomorphic granitoids comprise dominantly perthite, microcline (BaO up to 5.85 wt.%), quartz, albite and subordinate amphibole ± diopside ± epidote, allanite, titanite, magnetite ± ilmenite ± biotite ± calcite. Preservation of magmatic epidotes and resorbed boundaries indicates rapid ascent of the granitoid magma. Mylonitic deformation overprinted the southern part of the E-W trending pluton. Magmatic epidote with resorbed boundaries suggests rapid magma ascent. The metaluminous granitoids display affinities with shoshonitic rocks, i.e., enrichment of K₂O (5.79–11.41 wt.%), large ion lithophile elements (Ba 461.5–7004.8 ppm; Sr 151.3–3548.3 ppm), light rare earth elements (LREE 111.2–1317.7 ppm) and high K₂O/Na₂O (1.77–11.35) and La_CN/Yb_CN (11.7–82.48) ratios with both negative and positive Eu-anomalies (Eu/Eu* = 0.58–1.43; average 0.89). Trace element characteristics of zircons demonstrate their magmatic origin. Pseudosection modeling displays high temperature (∼800°C), high fO₂ (ΔNNO +0.8 to +2.6), and CO₂ activity (0.9) of the magma that intruded at shallow crustal depth (∼300 MPa). Biotite remains unstable at this physicochemical condition of the shoshonitic magma. Metaluminous nature, high (La/Yb)_CN (11.7–82.48) and Sr/Y (6.46–277.21) ratios, and Nb/U (avg. 7.4), Ce/Pb (avg. 6.8), Nb/Ta (avg. 11.9), Zr/Hf (avg. 31.61), and low Rb/Sr (0.09–1.39) ratios of these rocks indicate the derivation of the magma from partial melting of the mafic lower crust. Batch melting modeling shows the granitoid magma originated from 5 to 30 % batch melting of K–Ba–Sr-rich shoshonitic mafic (hornblende granulite) source. The study proposes new (Ba + Sr)–Ti–P and Ba–Sr–Ti triangular diagrams for distinguishing mantle vs. crustal sources of post-collisional granitoids.

本文报道了位于东系（949.4±2.3 Ma）的超经典花岗岩类岩体的岩石成因；新LA-ICPMS锆石U-Pb测年)沿区域剪切带在印度东部的格伦维里安萨特普拉造山运动碰撞后阶段。半自形花岗岩主要由花岗石、微斜长石（BaO高达5.85 wt.%）、石英、钠长石及其下属角闪石±透辉石±绿帘石、allanite、钛矿、磁铁矿±钛铁矿±黑云母±方解石组成。岩浆岩绿帘石和吸收边界的保存表明花岗岩类岩浆的快速上升。糜棱岩变形覆盖了东西向岩体的南部。具有吸收边界的岩浆绿帘岩表明岩浆迅速上升。成矿花岗岩类与粗玄岩具有亲缘关系，富集K2O （5.79 ~ 11.41 wt.%）、大离子亲石元素(Ba 461.5 ~ 7004.8 ppm；Sr 151.3 ~ 3548.3 ppm)，轻稀土元素（LREE 111.2 ~ 1317.7 ppm），高K2O/Na2O（1.77 ~ 11.35）和LaCN/YbCN（11.7 ~ 82.48）比值，Eu-异常呈负、正(Eu/Eu* = 0.58 ~ 1.43；平均0.89)。锆石微量元素特征表明其岩浆成因。伪剖面模拟显示，在地壳浅深度（~ 300 MPa）侵入的岩浆具有高温（~ 800℃）、高fO2 （ΔNNO +0.8 ~ +2.6）和高CO2活度（0.9）。黑云母在玄武质岩浆的这种物理化学条件下仍然不稳定。成矿性质、高（La/Yb）CN（11.7 ~ 82.48）和Sr/Y（6.46 ~ 277.21）比值、Nb/U（平均7.4）、Ce/Pb（平均6.8）、Nb/Ta（平均11.9）、Zr/Hf（平均31.61）和低Rb/Sr（0.09 ~ 1.39）比值表明岩浆来源于基性下地壳部分熔融作用。间歇式熔融模拟表明，花岗质岩浆起源于5 ~ 30 %的富k - ba - sr闪玄岩基性（角闪质麻粒岩）间歇式熔融源。该研究提出了新的(Ba + Sr) -Ti-P和Ba - Sr - ti三角图，用于区分碰撞后花岗岩类的地幔和地壳来源。

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引用次数: 0

Corrigendum to “The heterogeneous distribution of critical metal mineral resources: An impending geopolitical issue” [Geosystems and Geoenvironment 4 (2025) 100288] “关键金属矿产资源的非均匀分布：一个迫在眉睫的地缘政治问题”的勘误表[地球系统与地球环境4 (2025)100288]

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-05-28 DOI: 10.1016/j.geogeo.2025.100394

David I. Groves , D. Müller , M. Santosh , Cheng-Xue Yang

引用次数: 0

Integration of geospatial techniques and machine learning in land parcel prediction 地理空间技术与机器学习在地块预测中的整合

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-02-25 DOI: 10.1016/j.geogeo.2025.100371

Nekkanti Haripavan , Subhashish Dey , Chimakurthi Harika Mani Chandana

The integration of geospatial techniques and machine learning algorithms has revolutionized our ability to analyze and predict changes in land parcels. In this research work leverage the power of Google Earth Engine to observe and interpret historical data spanning the last 2014–2023 years, in order to make informed predictions about future land parcel transformations. Our research will highlight the key components of this plan including data acquisition, preprocessing, feature engineering, and the application of machine learning models. We will explore how Google Earth Engine provides a robust platform for accessing vast geospatial datasets and performing complex analyses. By harnessing the temporal and spectral information captured by Earth observation satellites, we aim to identify patterns and trends in land parcel changes. These insights are used to train and fine-tune our machine learning models, which will subsequently forecast future land parcel developments. The project underscores the practical significance of our research work, as it can be applied to more domains such as urban planning, agriculture, forestry, and environmental monitoring. Furthermore, it showcases the potential of technology to enhance our understanding of the dynamic nature of our environment, and the role that predictive analytics plays in informed decision-making. One significant benefit is the feature selection that may be customized thanks to machine learning and geospatial approaches. Researchers and practitioners can customize their models by choosing the most pertinent variables for each land parcel forecasts from a wide range of spatial features. This flexibility guarantees that models can concentrate on the spatial features that have the biggest influence on the desired outcomes, improving the forecasts' overall performance and interpretability.

地理空间技术和机器学习算法的结合彻底改变了我们分析和预测地块变化的能力。在这项研究工作中，利用谷歌地球引擎的力量来观察和解释过去2014-2023年的历史数据，以便对未来的地块变化做出明智的预测。我们的研究将重点关注该计划的关键组成部分，包括数据采集、预处理、特征工程和机器学习模型的应用。我们将探讨谷歌地球引擎如何为访问大量地理空间数据集和执行复杂分析提供一个强大的平台。通过利用地球观测卫星捕获的时间和光谱信息，我们的目标是确定地块变化的模式和趋势。这些见解用于训练和微调我们的机器学习模型，这些模型随后将预测未来的地块发展。该项目强调了我们的研究工作的现实意义，因为它可以应用于更多的领域，如城市规划、农业、林业和环境监测。此外，它还展示了技术的潜力，可以增强我们对环境动态性质的理解，以及预测分析在知情决策中发挥的作用。一个重要的好处是，由于机器学习和地理空间方法，可以定制特征选择。研究人员和实践者可以通过从广泛的空间特征中选择最相关的变量来定制他们的模型。这种灵活性保证了模型可以专注于对预期结果影响最大的空间特征，从而提高预测的整体性能和可解释性。

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引用次数: 0

Nappe tectonics in the Matomb-Hegba area, South-Central Cameroon: Implications on the tectonic evolution of the Yaoundé Group in the Central African Orogenic Belt 喀麦隆中南部Matomb-Hegba地区推覆构造：对中非造山带yaound<e:1>群构造演化的启示

Geosystems and Geoenvironment

Pub Date : 2025-05-01 Epub Date: 2025-02-28 DOI: 10.1016/j.geogeo.2025.100372

Victor Metang, Henri Appolinaire Kenzo, Rose Noel Ngo Belnoun, Dior-Christelle Mboutchouang, Steve Franck Bamou-Wandji, Brigitte Domkam, Boris Toyi Tchouta

This paper documents the thrust tectonics in the Yaoundé Group using detailed field mapping and satellite imagery data. The litho-stratigraphic of the Matomb-Hegba area located W of the Pan-African Yaoundé series comprised two main metasedimentary units: (1) garnet-kyanite migmatites at the top, dated at 622 ± 43 Ma, and (2) garnet-rutile micaschists at the bottom, with ages ranging between 546 and 604 Ma. The contact between the two lithological units is materialized by a ductile shear zone evidenced by structural and remote sensing data: inversion of the foliation at the contact of the shear zone, P₂ folds with southern vergence, E-W to NE-SW sinistral shear planes, uniform dip (towards the SE) and several criteria indicating a sinistral and dextral kinematics respectively in light grey mylonites and in dark grey mylonites along the ductile shear zone. During D₂ deformation stage, subhorizontal S₂ foliation associated to NE-SW Lm₂ mineral lineations were developed in garnet-kyanite migmatites. The thrusting contact zone is characterized by mylonitized micaschists (light grey mylonites) and migmatites (dark grey mylonites) separated by talcschist and amphibolite boudins which would have served as a ‘‘soap layer’’ leading to the slipping of garnet-kyanite migmatites over garnet-rutile micaschists. The disposition of garnet-kyanite migmatites (sometimes outcrop in the form of klippes) over garnet-rutile micaschists, the presence of a ductile shear zone at the contact of the two lithological units, and the NE-SW mineral lineation suggest the existence of at least two tectonic nappes (garnet-kyanite migmatites and garnet-rutile micaschists) with NE-SW-trends in the Yaoundé Group. This nappe disposition induced by ductile shear corroborates well with the compressive shear tectonics as described in the NE of Brazil and in the northern and eastern part of the Saharan Block.

本文利用详细的野外填图和卫星影像资料，记录了雅温顿群的逆冲构造。Matomb-Hegba地区的岩石地层主要包括两个变质沉积单元：(1)顶部的石榴石-蓝晶石混合岩，年龄为622±43 Ma；(2)底部的石榴石-金红石云母岩，年龄为546 ~ 604 Ma。两个岩性单元之间的接触是由韧性剪切带体现的，构造和遥感数据证明：剪切带接触处的片理反转，P2褶皱带向南辐合，E-W至NE-SW左旋剪切面，均匀倾角（向东南）以及沿韧性剪切带的浅灰色糜棱岩和深灰色糜棱岩分别具有左旋和右旋运动学的若干标准。D2变形阶段，石榴蓝杂岩发育与NE-SW Lm2矿物线理相关的亚水平S2片理。逆冲接触带以糜棱岩化的云母岩（浅灰色糜棱岩）和杂闪岩（深灰色糜棱岩）为特征，由滑石片岩和角闪岩分离，形成“肥皂层”，导致石榴石-蓝晶石杂闪岩在石榴石-金红石云母岩上滑动。石榴石-蓝晶石混闪岩（有时以短棱岩形式露头）在石榴石-金红石云母岩上的分布，两个岩性单元接触处韧性剪切带的存在，以及NE-SW向的矿物线理表明，在姚文德岩群中至少存在两个NE-SW向的构造推覆体（石榴石-蓝晶石混闪岩和石榴石-金红石云母岩）。这种韧性剪切作用下的推覆构造与巴西东北部和撒哈拉地块北部和东部的压缩剪切构造相吻合。

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引用次数: 0