Search Results (236)

The formation of tectonic–magmatic–sedimentary processes during the Permian in the Beishan region represents a highly debated research topic along the southern margin of the Central Asian Orogenic Belt and even globally: does it mark the final subduction and amalgamation of the Paleo-Asian Ocean, or does it instead represent rifting superimposed upon an earlier orogen? New field observations combined with geochemical analyses reveal that the Liuyuan area is dominated by Early Permian basalts, associated with a rifting sedimentary sequence. During the Mid–Late Permian, gabbro–rhyolite associations were emplaced, accompanied by minor lacustrine sedimentation. The late stage was characterized by minor granitic intrusions or dikes with adakitic affinities, culminating in the emplacement of lamprophyre dikes. The basalts and gabbros in the Liuyuan area display mantle-derived geochemical signatures, with compositions intermediate between MORB and OIB. The exposed Permian basalt–rhyolite bimodal magmatic suite represents a genetically integrated rift-related rock series. Geochemical data from the Ordovician granites and schists within the belt reveal adakitic characteristics, implying that the Permian granitic rocks largely represent remelting products of these early granitic and schistose protoliths. Collectively, the lithological characteristics and magmatic associations clearly demonstrate that the tectonic setting during the Early Permian corresponded to a post-collisional extensional environment superimposed upon the early Paleozoic orogenic belt (Caledonian Huitongshan ophiolite–arc accretionary orogen), which subsequently underwent tectonic inversion to form the present-day orogenic structure. This paper proposes a theoretical model wherein the bimodal magmatic suite was generated by the upwelling of enriched asthenospheric mantle material, providing the driving mechanism for rifting. It formed within a post-collisional extensional environment developed over a complex pre-existing orogenic belt and was subsequently inverted, forming the current tectonic belt—a typical intracontinental Pyrenees-type orogeny. Full article

This study analyzes the educational and scientific potential of paleogeographic reconstruction as a contextualized geoscience teaching tool within the UNESCO Global Geopark of M’Goun (Central High Atlas, Morocco). It addresses a major limitation of Moroccan geology curricula, which mainly rely on generalized paleogeographic models disconnected from local geological realities and field evidence. The Ouaouizaght sector, characterized by a continuous Jurassic–Cretaceous sedimentary succession and well-preserved Middle Liassic facies, was selected as a representative case study for developing an integrated field-based educational framework. The methodological approach combines cartographic analysis, geological field observations, structural interpretation, and GIS-based spatial synthesis. Field investigations conducted along a northwest–southeast transect enabled the characterization of carbonate platform, slope, and distal hemipelagic environments. Meanwhile, they identified tectonic controls influencing facies organization and basin geometry. The integration of lithostratigraphic, paleoenvironmental, and structural data led to the reconstruction of a coherent paleogeographic model for the western edge of the Central High Atlas during the Middle Liassic. The main target audience of this research is Life and Earth Sciences (LES) teachers, both in initial training and continuing professional development, and indirectly secondary school students. This study highlighted the pedagogical value of combining fieldwork, spatial reasoning, and geological interpretation to support inquiry-based and contextualized geoscience education. Full article

The Mesozoic dykes in the Xingcheng area of western Liaoning Province in China were investigated through an integrated study involving zircon U–Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic compositions to elucidate their emplacement phases, petrogenesis, and tectonic setting. The dykes are classified into two groups: felsic (granite porphyry, granite aplite) and mafic (diabase, lamprophyre). Emplacement occurred in four discrete phases: Late Triassic (229–212 Ma), Early Jurassic (ca. 179 Ma), Late Jurassic (162–152 Ma), and Early Cretaceous (133–102 Ma). The felsic dykes are characterized by high SiO₂ and alkali contents, low TFeO and MgO abundances, and belong to the high-K calc-alkaline I-type granite series. The mafic dykes exhibit low SiO₂, elevated MgO, and high Na₂O contents, displaying both alkaline and calc-alkaline affinities. Both dyke suites are consistently enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and depleted in heavy rare earth elements (HREEs) and high field-strength elements (HFSEs). Zircon ε_Hf(t) values for the felsic dykes range from −22.3 to −7.4, corresponding to two-stage model ages (T_DM2) of 2613–1729 Ma, indicating derivation from partial melting of Neoarchean to Paleoproterozoic crustal material. Late Jurassic mafic dykes yield ε_Hf(t) values between −27.8 and −20.2, consistent with an origin from partial melting of enriched lithospheric mantle. In contrast, Early Cretaceous mafic dykes display a bimodal ε_Hf(t) distribution (−12.9 to −9.5 and +4.3 to +8.4), suggesting a predominant enriched mantle source with variable inputs from depleted mantle components. Integrated with regional tectonic reconstructions, the data indicate that the Xingcheng area evolved within a post-collisional extensional regime following the amalgamation of the North China Craton and the Central Asian Orogenic Belt during the Late Triassic. The Jurassic magmatic pulses are attributed to an active continental margin setting associated with subduction of the Paleo-Pacific Plate, whereas the Early Cretaceous phase reflects regional extension triggered by rollback of the subducting Paleo-Pacific slab. Full article

This article analyzes the information provided by the sedimentary sequences of 29 lakes in central Mexico, 10 of which are currently paleolakes. During the Late Quaternary, the lakes of central Mexico experienced environmental changes driven by global and local climatic and geological processes, showing regional trends of wet and dry periods. Paleoenvironmental reconstructions are based on the use of 20 indicators, including diatoms, pollen, geochemistry, mineralogy, granulometry, magnetic susceptibility, and isotopes. Seven major episodes are recognized in the historical evolution of the lakes of central Mexico: i. Late Miocene–Pliocene: A period that includes the formation of large lakes in central Mexico by volcano tectonic activity under a regime of continuous humidity. ii. Pleistocene–Drought and climatic variability of the interglacial period. iii. Drying and successive lacustrine transgression during the Last Glacial Maximum. iv. Spatial climate variability in the Heinrich 1 period. v. Lake regression and expansion of terrestrial vegetation in the Bølling–Allerød period. vi. Transgression of lakes of central Mexico during the Younger Dryas and mid-Holocene periods. vii. Late Holocene: A period that includes lake desiccation influenced by the impact of human activities. The analysis of the data allows us to propose six challenges for the scientific community in future research of central Mexico. Full article

Subsidence is the lowering of the ground surface caused by both natural processes, such as geological and tectonic dynamics, and anthropogenic activities related to land and resource use. Identifying and monitoring this phenomenon is essential for several reasons, including ensuring public safety, supporting the sustainable management of subsurface resources, and mitigating potential economic impacts. This study investigates ground deformation in an underexplored sector of the Calabria Region (Southern Italy), namely the Sant’Eufemia Plain. To this end, long-term Sentinel-1 datasets were processed using multi-temporal Synthetic Aperture Radar Interferometry techniques. Significant subsidence, reaching locally up to −17 mm/yr, was detected in the industrial area of San Pietro Lametino. Historical SAR datasets (ERS, ENVISAT) and optical imagery were used to reconstruct the long-term evolution of deformation since the 1990s. Satellite observations were integrated with rainfall records, piezometric data, and geotechnical modelling. A spatially distributed comparison between groundwater level variations and InSAR-derived deformation, supported by local time-series analysis, highlights weak and inconsistent correlations, indicating that groundwater fluctuations alone do not linearly control subsidence. The results suggest that subsidence is primarily associated with long-term consolidation processes affecting highly compressible Holocene deposits, likely enhanced by anthropogenic loading, while groundwater variations may contribute by modifying effective stress conditions within the subsoil. The relative contribution of these processes remains unquantified, highlighting the need for coupled hydro-mechanical investigations. Full article

Eyelid anomalies represent a relevant cause of corneal injury, including epithelial instability and recurrent erosions up to progressive stromal thinning, corneal melt, and, in severe cases, perforation leading to permanent visual impairment. Correction of eyelid dysfunction is the first step in managing these lesions. However, corneal damage may persist or progress despite adequate eyelid treatment. Therefore, a corneal surgical approach is necessary to preserve ocular surface integrity and visual function. This review synthesizes literature published between 2008 and 2025 on corneal complications secondary to eyelid anomalies and postoperative eyelid procedures. We analyzed the mechanisms of eyelid-induced corneal injury, indications for surgical treatment, and corneal surgical strategies, from surface-stabilizing techniques to tectonic interventions. Entropion and ectropion are the most common eyelid abnormalities associated with mechanical trauma and exposure-related corneal disease. Although definitive eyelid correction is necessary for corneal recovery, persistent epithelial defects, stromal thinning, corneal melt, and perforation frequently require corneal surgical management. Surface-stabilizing procedures, such as amniotic membrane transplantation, are effective in early disease stages, whereas progressive stromal defects necessitate tectonic approaches such as lamellar patch grafting or therapeutic keratoplasty. Interventions aimed at visual rehabilitation should be postponed until sustained ocular surface stability has been achieved. Effective management of eyelid-related corneal damage requires both eyelid surgical correction and corneal management. Close collaboration between corneal and oculoplastic surgeons helps achieving good anatomical outcomes and long-term ocular surface stability. Full article

On the lunar surface, wrinkle ridges, grabens, and lobate scarps represent key tectonic landforms that reflect the evolution of the Moon’s stress field and its tectonic processes. However, these linear structures often exhibit weak textures, low contrast, and large scale variations, making manual interpretation inefficient and subjective. To address this issue, this study introduces an improved YOLOv8 model, termed HL-YOLOv8, for the automated detection of lunar linear features. The model incorporates a multiscale lightweight channel attention (C2f_MLCA) module into the backbone network to enhance the extraction of fine-grained and weak-texture features and integrates a multihead self-attention (C2f_MHSA) module in the feature fusion stage to improve the modelling of long-range spatial dependencies. In addition, the combination of a dual focal loss and a diversified data augmentation strategy effectively mitigates the detection difficulties caused by class imbalance and weak-feature samples. The experimental results obtained using the global LROC-WAC image dataset demonstrate that HL-YOLOv8 significantly outperforms the baseline YOLOv8 and other comparative models in terms of precision, recall, and mAP@0.5. Specifically, the proposed model achieved an average precision of 73.5%, an average recall of 73.1%, and an average mAP@0.5 of 74.6% on the evaluation dataset, showing particularly strong performance in detecting elongated grabens and boundary-blurred lobate scarps. The global distribution maps derived from the model predictions indicate that HL-YOLOv8 can be applied to comprehensively reconstruct the spatial patterns of the three types of linear structures and identify potential new features in high-latitude and geologically complex regions, demonstrating excellent generalizability and robustness. This study provides an efficient and reliable framework for the automated identification and global mapping of lunar linear features and offers a transferable methodological reference for the tectonic interpretation of terrestrial planets. Full article

The Qingshankou Formation shales in the southeastern uplift of the Songliao Basin provide an ideal archive for constraining the controls of paleoenvironment on organic matter enrichment. Taking the shale succession at the Niaohexiang section of Binxian as the study object, we combined field sampling with TOC measurements, whole-rock X-ray diffraction, and major, trace, and rare earth element analyses. The strata are dominated by black shale and dark gray mudstone, with mineral assemblages composed mainly of clay, felsic, and carbonate minerals; argillaceous shale exceeds 60%. Normal alkanes display a post-peak distribution with C₂₇ as the dominant peak, low Pr/Ph ratios, and gammacerane index values of 0.18–0.26. Regular steranes are generally V-shaped, whereas some samples show high C₂₉ sterane contents and a reversed L-shaped pattern. Major elements are dominated by SiO₂ and Al₂O₃, trace elements such as Sr and Ba are relatively enriched, and rare earth elements show light REE enrichment with a pronounced negative Eu anomaly. These signatures indicate an upper-crustal felsic provenance and a continental island arc tectonic setting. Organic matter contents are low and derived mainly from terrestrial higher plants with minor aquatic input. Paleoenvironmental reconstruction suggests deposition in a freshwater to slightly brackish, semi-arid, anoxic-reducing shallow lacustrine setting with relatively low productivity, whereas dolostone formed under more saline, arid, and more productive conditions. Climatic fluctuations, salinity variations, and alternating redox states jointly controlled organic matter enrichment, and late-stage lacustrine salinization and anoxia associated with dolostone horizons enhanced organic matter preservation. Full article

Major earthquakes often induce multi-structural rupture styles, which serve as a crucial basis for understanding stress partitioning and strain adjustment within tectonic systems, as well as for constructing regional deformation models. The 1927 M 8.0 Gulang earthquake in the northeastern Tibetan Plateau exemplifies this phenomenon. This rare event, characterized by a single mainshock triggering multiple structural ruptures, resulted in approximately 40,000 casualties and numerous missing persons. In this study, we integrate interpretations of satellite remote sensing imagery, field observations of surface ruptures, and analyses of regional tectonic–geomorphic deformations to reconstruct the coseismic processes of the Gulang earthquake. Our findings reveal that the coseismic surface ruptures exhibit distinct mechanical characteristics driven by complex stress fields. Survey and analysis results indicate that regional tectonic compression oriented from SSW–SW to NNE–NE triggered the mainshock rupture. This stress regime caused nearly E–W folding of strata north of the Huangcheng–Shuangta Fault (HSF), alongside sinistral strike-slip motion in the central-eastern section and thrusting at the eastern end of the Southern Wuwei Basin Fault (SWBF). Blocked by the rigid Alxa Block to the north, comprehensive evidence—including the Late Holocene gravelly clay folded strata formed by north-to-south compression in the Liutiao Lake area, the geomorphic deformation characterized by higher northern and lower southern terraces on both sides of the east–west-trending fault, and the clockwise rotational tectonic surfaces developed at the eastern end of the HSF zone in Shuixiakou—indicates that the coseismic tectonic movement and energy transfer within the meizoseismal area underwent a rapid clockwise rotation from NE to S. This strain rotation induced N–S tensional rupturing along the southern branch of the eastern HSF and nearly E–W thrusting along the NNW-trending Wuwei–Gulang Fault (WGF). Furthermore, this intense and rapid clockwise rotation generated a transient extensional environment characterized by rapid E–W to SE stretching, leading to the formation of a newly identified, NNE-trending, high-angle dextral strike-slip normal fault (hereafter referred to as the NNEF). This process also triggered localized activity at the junctions between the NNEF and the Lenglongling Fault (LLLF), and between the WGF and the nearly E–W-trending Gulang Fault (GLF). We conclude that the seismogenic structure of the 1927 Gulang mainshock comprises three primary components: (1) a fault–fold belt consisting of the SWBF and the nearly E–W fold system north of the HSF; (2) the southern branch of the eastern HSF; and (3) the WGF. The observed segmental activities of the GLF and LLLF are attributed to local strain adjustments. By identifying the newly formed NNEF and characterizing these segmental activations, this study provides new insights into the mechanisms of local strain adjustment within the tectonic systems of the northeastern Tibetan Plateau. Full article

The reliability of bulk geochemical proxies for provenance analysis in heterogeneous clastic systems remains a critical yet underexplored issue. This study investigates the Lower Permian Shanxi Formation in the Southern North China Basin (SNCB) using an integrated approach combining major and trace element geochemistry, rare earth elements (REEs), and detrital zircon U–Pb geochronology. The results show that major element compositions have been significantly modified by diagenetic processes in tidal flat environments, limiting their applicability in tectonic discrimination. In contrast, immobile trace elements and REE patterns provide more robust constraints on source rock composition, suggesting predominantly felsic upper continental crustal sources. Detrital zircon age spectra reveal two dominant populations at 290–440 Ma and 1800–2500 Ma, indicating mixed provenance from the North Qinling Region (NQR) and the North China Craton (NCC). However, the application of classical discrimination diagrams is challenged by lithological heterogeneity, as the mixed presence of sandstone, sandy mudstone, and mudstone introduces compositional bias. Spatial variations among wells suggest differential contributions from continental island arc and active continental margin, likely controlled by paleogeographic configuration and sediment transport pathways. This study emphasizes the necessity of multi-proxy integration for reliable provenance reconstruction in complex sedimentary systems. Full article

Sub-sag 21 in the eastern Yangjiang Sag, Pearl River Mouth Basin, South China, contains a thick lacustrine source-rock interval within the lower Wenchang Formation and is a major exploration target on the northern margin of the South China Sea. However, the timing of deposition during the early to middle Eocene remains poorly constrained, and the applicability of quantitative palaeoclimate reconstruction methods in low-latitude lacustrine basins requires further evaluation. In this study, we analyzed mudstones from the lower Wenchang Formation in Well E1. Using cyclostratigraphic constraints, we applied AstroGeoFit to construct an astronomically tuned age model, and combined palynological coexistence analysis with geochemical weathering proxies and linear–regression calibration to quantitatively reconstruct and cross-validate mean annual temperature and mean annual precipitation. Within this time-calibrated framework, we further quantified organic-carbon burial to evaluate the relationship between palaeoclimate evolution and organic-matter enrichment. The AstroGeoFit results indicate that the top of the lower Wenchang Formation in Well E1 is constrained to 44.563 Ma, and that the studied succession spans 50.249–44.563 Ma. Palynological coexistence analysis identifies three palaeoclimate phases within this interval. Method evaluation shows that the temperature reconstruction based on major-element geochemistry agrees well with the pollen-based temperature record, whereas one precipitation reconstruction based on weathering proxies shows the most robust agreement and stability relative to the pollen-based precipitation record. Reconstructed mean annual temperature ranges from 10.77 to 22.20 °C, and reconstructed mean annual precipitation ranges from 1188.27 to 1871.89 mm. Correlation analyses on the tuned timescale show that precipitation is more strongly associated than temperature with organic-matter accumulation parameters, including total organic carbon and organic carbon accumulation rate, indicating that organic carbon burial in the eastern Yangjiang Sag lake basin was mainly controlled by hydrological forcing. During the Early Eocene Climatic Optimum, carbon burial in low-latitude lakes was, therefore, not a simple response to elevated temperature, but instead reflected the integrated effects of precipitation, runoff, stratification, material supply, transport, and preservation. The evolutionary sequence further suggests that early high productivity was diluted by rapid sedimentation, reducing total organic carbon; subsequent cooling, lake deepening, and strengthened stratification enhanced organic matter preservation; and finally, tectonic subsidence together with regional humidification promoted the development and long-term preservation of high-quality lacustrine source rocks. Full article

The ambiguous evolution of the depositional system in the Pinghu Formation of Block K, Xihu Depression, East China Sea Basin, has long constrained the accuracy of reservoir prediction in this area. Based on petrological analysis, sedimentary system identification, and depositional model reconstruction, this study systematically elucidates the sedimentary evolution of the Pinghu Formation in Block K. The results indicate that the Pinghu Formation exhibits diverse lithologies and multiple types of grain-size distribution, reflecting complex hydrodynamic conditions. The early stage was dominated by tidal processes with fluvial influence, transitioning to fluvial dominance in the late stage. The depositional system evolved through a complete sequence: the early stage (E2pSQ1) was characterized by a tide-dominated delta, the middle stage (E2pSQ2) by fluvial-tidal interaction, and the late stage (E2pSQ3) by an overwhelmingly fluvial-dominated system. This evolution was controlled by the combined effects of a persistently increasing sediment supply and episodic relative sea-level fall, with the transition mechanism primarily governed by tectonic-eustatic coupling. In the lowstand systems tract of the middle-upper section, a “high-supply, high-progradation” fluvial-dominated delta developed in the Kongbei fault-step zone, whereas a “low-supply, low-progradation” minor fluvial system formed in the Kongnan fault-step zone. Here, tidal reworking was weak, and tidal flats developed only locally. In contrast, the highstand systems tract in the middle-lower section was dominated by a tide-dominated delta in the Kongnan fault-step zone, while the Kongbei fault-step zone remained a “low-supply, low-progradation” minor fluvial system. The established depositional models provide a geological basis for reservoir prediction and hydrocarbon exploration in the Pinghu Formation of Block K. Full article

Accurate seamount identification is important for understanding submarine tectonic and magmatic processes and for supporting deep-sea geomorphological analysis. However, seamount recognition faces a severe class imbalance as abyssal plains constitute the majority of deep-sea topography while seamounts occupy only a minimal portion, which makes accurate segmentation difficult. To address this issue, this study proposes an improved U-Net architecture, termed Spatial–Channel Reconstruction U-Net (RSCU-Net), built upon a Residual Spatial–Channel Reconstruction Convolution (Res-SCConv) module. The Res-SCConv module is embedded into each skip connection of the U-Net architecture. The model combines a Spatial Reconstruction Unit (SRU) and a Channel Reconstruction Unit (CRU) to suppress dominant background interference and reduce channel redundancy, and further introduces a Selective Kernel-based Multi-scale Gradient Module (SK-MGM) to improve boundary refinement. Experiments on the GEBCO 2023 bathymetric dataset, including 696 training samples and 88 independent test samples, show that RSCU-Net achieves an Accuracy of 0.938, Recall of 0.833, F1-score of 0.720, and IoU of 0.563. Compared with the baseline U-Net, Recall improves from 0.741 to 0.833 and IoU from 0.405 to 0.563. Additional validation on the Suda Seamount dataset yields an Accuracy of 0.987, F1-score of 0.958, and IoU of 0.920, demonstrating the robustness and generalization capability of the proposed method. Full article

The Permian Wargal Formation of the western Salt Range preserves a shallow marine carbonate-ramp succession, in which heterogeneity reflects coupled depositional architecture, facies-selective diagenesis, and deformation-related structural compartmentalisation of the Wargal interval. This study integrates balanced restoration with stratigraphic logging, microfacies analysis, paragenetic reconstruction, and quantitative pore-network topology to evaluate how stratigraphic packaging and diagenetic overprint govern connected pathway development within a structurally partitioned fold–thrust setting. Balanced restoration of a representative transect yields 1.1336 km of minimum tectonic shortening (18.7%) and indicates shortening shared between thrust slip and distributed folding, providing an admissible geometric framework for assessing compartmentalisation. The Wargal succession is ~130 m thick and organised into three carbonate packages bounded by laterally persistent argillaceous marker intervals (~21–23 m and ~98–105 m), with grain-supported shoal to shoal-margin facies dominating intervening units. Diagenesis is strongly facies-selective; grain-supported microfacies record progressive calcite cementation that occludes pore throats, whereas mud-supported facies retain microporosity but are preferentially modified by neomorphism, compaction, and pressure-solution fabrics. Image-based analysis of 20 thin-section fields of view shows that pore connectivity varies systematically among microfacies and that a connectivity-weighted index ($I_{\mathrm{conn}}$) covaries more closely with skeleton-derived connectivity than with segmented areal porosity (${\varphi }_{2D}=0.124$–9.750%). The combined results quantify the decoupling between pore volume and connectivity and provide a basis for predicting reservoir-quality evolution from facies architecture, diagenetic sequence, and structural segmentation, with direct relevance to subsurface characterisation of marine carbonate successions in hydrocarbon systems. Full article

The study presents new data on the distribution, mapping, and morphostratigraphic characteristics of pediment deposits in the Montefeltro region (Italian Apennines), within the Val Marecchia Nappe. The Montefeltro landscape represents a clear example of morphology controlled by lithostructural features, with reliefs emerging from the surrounding terrain due to selective erosion. Its evolution has also been strongly influenced by climatic variations during the Middle–Late Pleistocene and the Holocene. Broad, gently sloping surfaces at the base of structural reliefs, together with associated debris deposits, are interpreted as erosional–depositional pediments formed under cold-climate, periglacial conditions during major Pleistocene glacial phases. Stratigraphic data from boreholes allowed the identification of pediment boundaries, thicknesses, and spatial extent, enabling reconstruction of the relict paleotopography and correlation with fluvial terraces. Two distinct lithological assemblages indicate different sediment sources and slope evolution pathways. Over time, pediments became disconnected from the present topography and were progressively dissected and terraced by fluvial incision, while recent slope adjustment is limited to modern drainage systems. This evolution reflects the combined influence of tectonic structure, lithology, and Quaternary climate change, confirming a regional trend of intensified fluvial deepening in the Marche Apennines. The study focuses on three representative areas: San Marino, Montecopiolo and Sassi Simone and Simoncello. Full article