Geosystems and Geoenvironment最新文献

{"title":"Source-to-sink history of detrital garnet from coastal dune sands in SW Mexico","authors":"Lizeth Carlos Delgado ,&nbsp;Juan J. Kasper-Zubillaga ,&nbsp;Raymundo G. Martínez-Serrano ,&nbsp;Mayumy Amparo Cabrera Ramírez ,&nbsp;Elsa Arellano-Torres ,&nbsp;José Luis Sánchez Zavala","doi":"10.1016/j.geogeo.2025.100381","DOIUrl":"10.1016/j.geogeo.2025.100381","url":null,"abstract":"<div><div>A morphological and geochemical study of detrital garnet was conducted to assess its utility in understanding sedimentary processes in coastal dune sands caused by in a weathering-limited erosion regime along the southwestern coast of Mexico. Multiple analytical techniques helped to elucidate the garnet's provenance, shape modification and surface alteration during its source-to-sink sedimentary dispersal. A Wavelength Dispersive Spectrometry (WDS) in an Electron Microprobe Analyzer (EMPA) (n = 89) revealed the dominance of almandine as the main mineral type related to the ortho-paragneiss source rocks from the Oaxacan Complex with a lesser contribution from the Xolapa Complex, outcropping in northwestern of the coastal dune sands. Scanning Electron Microscopy (SEM) helped to assess the compactness and convexity of shape descriptors by contouring the outline of detrital garnet (n = 200) and to identify the microtextures of the mineral's surface. A Raman Spectroscopy (n = 17) was employed to determine the presence of hydroxide or oxyhydroxide coatings to quantify the chemical weathering degree caused by steady and shallow burial conditions. Results show that the detrital garnet mainly underwent aeolian abrasion followed by fluvial subaqueous and marine controls. The former was supported by the quantification of moderate to high compactness and convexity values and the SEM observation of aeolian mechanical microtextures like bulbous edges, adhering particles and abrasion fatigue compared to the subaqueous microtextures as large conchoidal fractures (&gt;50 µm). Finally, we found that low to moderate chemical dissolution control modified the detrital garnet's surficial texture, evidenced by chemical microtextures like solution pits, etch pits, etch features, imbricate wedge marks and mound features. Hence, detrital garnet dissolution was dominated by its chemical composition, the nonstoichiometric character of the dissolution rate and its crystallographic forms.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100381"},"PeriodicalIF":0.0,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143739193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biotite as a petrogenetic discriminator in the polymetamorphosed rocks: A case study from the Champaner supracrustal rocks, Western India","authors":"Parita K. Gorania ,&nbsp;Gayatri N. Akolkar ,&nbsp;Aditya U. Joshi ,&nbsp;Manoj A. Limaye ,&nbsp;Mahendra K. Singh","doi":"10.1016/j.geogeo.2025.100380","DOIUrl":"10.1016/j.geogeo.2025.100380","url":null,"abstract":"<div><div>The mineral chemistry of Fe-Mg biotite has served as an aid to the petrogenesis of igneous rocks, especially for identifying the parent magma compositions. Though the interpretation of igneous and metamorphic processes utilizing biotite mineral chemistry is not upfront, it certainly provides preliminary insights into the petrogenetic characteristics of rocks. Apart from thermometry and chronology, studies emphasizing on the significance of biotite mineral chemistry for unveiling the protolith compositions, grade of metamorphism, origin, and P-T conditions of metamorphic rocks are poorly documented in the literature. Here we employ biotite mineral chemical compositions i.e., EPMA (electron probe micro-analyzer) data from the metapelitic rocks of the Meso-Neoproterozoic Champaner Group, exposed as an arcuate fold belt in western India to unravel the metamorphic rock record. This group of rocks display a complex deformational and polymetamorphic history, evident in distinct mineral assemblages that reflect regional, contact, and combined regional-contact metamorphism. The field observations, mesoscopic features of rocks, reaction textures, and biotite petrographic characteristics have revealed three distinct varieties of metapelitic rocks i.e., phyllites, spotted phyllites, and hornfelses. The mineral chemistry and cation substitution mechanisms of biotite selected from phyllite, spotted phyllite and hornfels suggests, the chemical composition of biotite in these rocks is a function of the bulk rock composition, co-existing minerals, type, and grade of metamorphism and thereby attesting to the pressure-temperature conditions of rock. Further, various compositional classification diagrams and Ti-in biotite thermometry demosntrate an increase in the grade of metamorphism from west to east of Champaner Group with intermittent as well as late-stage plutonic felsic intrusions. Thus, biotite being frequently the dominant or sometimes even sole Fe-Mg mineral with temperature-pressure driven substitutions in low-grade metamorphic rocks can offer a unique opportunity to unlock valuable insights into their metamorphic history.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100380"},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ozone patterns in Maceió: Insights into seasonal and geographic varibility","authors":"Amaury de Souza ,&nbsp;Celina M. Takemura ,&nbsp;Deniz Özonur ,&nbsp;Elias Silva de Medeiros ,&nbsp;Ivana Pobocikova ,&nbsp;Janice F. Leivas ,&nbsp;José Francisco de Oliveira-Júnior ,&nbsp;Kelvy Rosalvo Alencar Cardoso ,&nbsp;Marcel Carvalho Abreu ,&nbsp;Wagner Alessandro Pansera ,&nbsp;Jose Roberto Zenteno Jimenez ,&nbsp;Sneha Gautam","doi":"10.1016/j.geogeo.2025.100379","DOIUrl":"10.1016/j.geogeo.2025.100379","url":null,"abstract":"<div><div>This study analyzes the Total Ozone Column (TCO) over six cities in Alagoas, Brazil, aiming to evaluate their spatial and temporal homogeneity and identify seasonal and annual patterns from 2008 to 2016. TCO is a key indicator for monitoring the ozone layer and its implications for public health, given ozone's role in filtering ultraviolet radiation. The analysis utilized satellite-derived TCO data, with variance homogeneity assessed using the Bartlett test at a 95% significance level. Descriptive statistical analyses characterized the temporal distribution of TCO values, and probability density functions (PDFs) identified the best-fitting statistical distribution.</div><div>The findings indicate significant homogeneity in annual and seasonal TCO concentrations, with an annual mean of 263.24 ± 9.91 DU. A biannual TCO cycle was observed, with peaks in spring and lows in fall, influenced by Earth's orbit and ozone photochemistry. The data were best represented by a normal distribution, reflecting the role of the Brewer-Dobson Circulation in maintaining ozone uniformity and mitigating disruptions from phenomena like the Antarctic Polar Vortex.</div><div>These results emphasize the need for continuous monitoring of ozone variability, as fluctuations in TCO can affect ultraviolet radiation levels and, consequently, public health outcomes such as skin cancer and ocular diseases. The study underscores the importance of integrating TCO data into environmental policies and public health strategies, particularly in regions with high solar radiation exposure. The study's limited statistical sensitivity and geographic coverage highlight the necessity of further research on factors influencing ozone distribution and its broader environmental and health implications.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100379"},"PeriodicalIF":0.0,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assimilation of seismic attenuation model of NW Himalaya and its surrounding region","authors":"Vandana,&nbsp;Naresh Kumar","doi":"10.1016/j.geogeo.2025.100378","DOIUrl":"10.1016/j.geogeo.2025.100378","url":null,"abstract":"<div><div>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 (<em>Q_c</em>) across three lapse time windows (LTWs) at varying frequencies. Our results reveal that <em>Q_c</em> increases with both frequency and LTW, suggesting a depth-dependent nature of seismic attenuation in the region. The average attenuation relationships for <em>Q_c, Q_α</em> and <em>Q_β</em> across the Northwest Himalaya are determined as follows for LTWs of 20, 30, and 40 s, respectively: <em>Q_c</em> = (74 ± 14)<em>f</em> ^(1.27±0.06), <em>Q_c</em> = (103 ± 26)<em>f</em> ^(1.16±0.08), and <em>Q_c</em> = (140 ± 41)<em>f</em> ^(1.10±0.09). Our findings reveal significant variability in <em>Q_c, Q_α</em> and <em>Q_β</em> 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: [<em>Q_α,β,c</em>⁻¹(HH) &lt; <em>Q_α,β,c</em>⁻¹(SH) &lt; <em>Q_α,β,c</em>⁻¹(IGP) &lt; <em>Q_α,β,c</em>⁻¹(LH) &lt; <em>Q_α,β,c</em>⁻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.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100378"},"PeriodicalIF":0.0,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geohazard impact and gas reservoir pressure dynamics in the Zagros Fold-Thrust Belt: An environmental perspective","authors":"Mahsa Asghari ,&nbsp;Zahra Maleki ,&nbsp;Ali Solgi ,&nbsp;Mohammad Ali Ganjavian ,&nbsp;Pooria Kianoush","doi":"10.1016/j.geogeo.2025.100362","DOIUrl":"10.1016/j.geogeo.2025.100362","url":null,"abstract":"<div><div>The Zagros Fold-Thrust Belt (ZFTB) presents a unique intersection of geohazards and gas reservoir dynamics, shaped by the ongoing tectonic activity resulting from the collision of the Arabian and Eurasian plates. This study aims to assess the risk of earthquake-induced landslides and their impact on gas reservoir pressure dynamics – with a particular focus on the Kabir Kuh gas field – identified as a critical area for monitoring due to its vulnerability to seismic events. A novel hybrid model is introduced that integrates geographic information system (GIS) mapping, decision support system (DSS) modeling, and machine learning algorithms. By analyzing a century's worth of seismic data alongside real-time environmental parameters, the model demonstrates a predictive accuracy of 92% using Random Forest algorithms, significantly outperforming traditional methods. The findings reveal a strong correlation between seismic activity and fluctuations in gas reservoir pressure, with an average pressure change of ±150 psi observed during significant seismic events. A landslide susceptibility map was generated, pinpointing regions that require proactive management strategies, particularly where significant landslide potential threatens gas field stability. Identifying the Seymareh landslide as a monumental geological event underscores the impact of landslide hazards on gas field integrity. This research emphasizes the integration of advanced predictive techniques into seismic risk assessments, providing actionable insights for the sustainable gas reservoir management in seismically active regions. The necessity for continuous monitoring and the implementation of advanced geotechnical measures are highlighted as essential components of effective geohazard management. This study contributes to understanding the interplay between seismic hazards and gas reservoir dynamics, offering a comprehensive framework for future research and practical applications in risk management and environmental sustainability.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100362"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of gneisses and granitoids from Southern Bastar Craton, India: A geochemical insight to crustal evolution","authors":"Soumya Mitra ,&nbsp;Santa Dolui ,&nbsp;Asutosh K Tripathy","doi":"10.1016/j.geogeo.2025.100377","DOIUrl":"10.1016/j.geogeo.2025.100377","url":null,"abstract":"<div><div>This study investigates the geochemical evolution and petrogenesis of gneisses and granitoids from the southern part of the Bastar Craton, India, to understand the crustal evolution. The study incorporates the result on major, minor, trace and rare earth elements (REE) interpretation. The gneisses, classified as high alumina granodiorite to granite, peraluminous and exhibit geochemical signatures typical of Archaean TTGs, including enrichment in large ion lithophile elements (LILE) and depletion in high field strength elements (HFSE) with notable negative anomalies in elements like Nb, P, and Ti. In contrast, the granitoids show a meta-aluminous to per-aluminous composition, with higher K₂O/Na₂O ratios and pronounced enrichment in LILE with higher Sr, Ba, Zr, Nb, Y and Yb contents than the gneisses. These patterns suggest a progressive geochemical evolution from gneiss to granitoids. The study put forward two distinct subduction phases contributing to the formation of these rocks. The initial phase associated with a pre- to syn-collisional tectonic setting in a flat low-angle subduction at shallower depth and minimal interaction between slab melts and the mantle wedge. Whereas, the later one is characterized by a collision to subduction transition in a post-collisional setting with gradual increase in mantle-wedge interaction at a relatively greater depth, involving a steeply dipping subduction process. This dual-phase subduction model highlights the tectonic shift in the region over time and provides a comprehensive understanding of the geological evolution of the Bastar Craton.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100377"},"PeriodicalIF":0.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The future of recycling for critical metals: The example of EV batteries","authors":"Yanyan Zhao,&nbsp;Gurpreet Kaur","doi":"10.1016/j.geogeo.2025.100376","DOIUrl":"10.1016/j.geogeo.2025.100376","url":null,"abstract":"<div><div>Across the globe, the uptake of electric vehicles (EVs) has grown rapidly in recent years. With most EVs using lithium-ion batteries, there is a keen focus on the recovery of key battery metals: lithium (Li), nickel (Ni) and cobalt (Co), as well as graphite for the sustainable growth of the electric vehicle industry. This short review briefly introduces EV batteries, discusses EV battery recycling status and market outlook, recent technology advancement, challenges and opportunities and current government initiatives.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100376"},"PeriodicalIF":0.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiple drivers of the recent South Lhonak glacial lake outburst flood in Sikkim Himalaya and its aftermath on Teesta River Valley","authors":"Soumik Saha ,&nbsp;Biswajit Bera ,&nbsp;Debashish Sengupta ,&nbsp;Uttam Mukhopadhyay ,&nbsp;Debasis Ghosh ,&nbsp;Lakpa Tamang ,&nbsp;Sumana Bhattacharjee ,&nbsp;Nairita Sengupta","doi":"10.1016/j.geogeo.2025.100375","DOIUrl":"10.1016/j.geogeo.2025.100375","url":null,"abstract":"<div><div>Glacial lake outburst floods (GLOFs) are the most severe cryospheric hazard in the ‘Third Pole’ region, encompassing the Tibetan Plateau and surrounding areas including the Himalayas, Hindu Kush, Kunlun, and Tianshan mountains. Understanding the proper response of glaciers to the current situation of global warming is vital because of their role as a water source in the Asian region. Numerous glacial lakes are formed in the higher Himalayan areas due to the contemporary increase in global temperature. The upper part of the Teesta Basin, Sikkim hosts several glacial lakes including one of the largest and fastest growing South Lhonak Lake (5200 m from the mean sea level). Recently, a devastating GLOF event occurred in South Lhonak Lake after the breaching of moraine dams on midnight of October 3, 2023. This disastrous GLOF event collapsed the Chungthang Dam, located approximately 65 km downstream of the lake and accelerated extensive casualties along with infrastructural damages. It is identified that; the impact of cloudburst may be a significant triggering factor behind this event. The satellite imagery and digital elevation models also revealed that a sudden collapse of lateral moraine eventually produced an impulse wave which accelerated the breaching process. Additionally, this study also combined with advanced remote sensing applications. Satellite imageries indicate a huge reduction of the lake area after the GLOF event (1.66 km² before the GLOF event and 0.63 km² after the GLOF). The overtopping volume of the water has been estimated as approximately 106,400 <span><math><msup><mrow><mi>m</mi></mrow><mn>3</mn></msup></math></span>, with a duration of 12.78 s. The peak discharge during overtopping touched approximately 16,651.02 cumecs, indicating the maximum flow rate during the phase. The results have been validated by the high-resolution satellite data across various sites.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100375"},"PeriodicalIF":0.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tonian shoshonitic to ultrapotassic granitoids from Chhotanagpur Gneissic Complex, Eastern Indian Shield: Age, origin and tectonic implications","authors":"Ankita Basak ,&nbsp;Bapi Goswami ,&nbsp;Yoann Gréau ,&nbsp;Susmita Das ,&nbsp;Chittaranjan Bhattacharyya","doi":"10.1016/j.geogeo.2025.100373","DOIUrl":"10.1016/j.geogeo.2025.100373","url":null,"abstract":"<div><div>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 <em>f</em>O₂ (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.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100373"},"PeriodicalIF":0.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143593753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"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","authors":"Victor Metang,&nbsp;Henri Appolinaire Kenzo,&nbsp;Rose Noel Ngo Belnoun,&nbsp;Dior-Christelle Mboutchouang,&nbsp;Steve Franck Bamou-Wandji,&nbsp;Brigitte Domkam,&nbsp;Boris Toyi Tchouta","doi":"10.1016/j.geogeo.2025.100372","DOIUrl":"10.1016/j.geogeo.2025.100372","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100372"},"PeriodicalIF":0.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}