The so-called Harmancık “purple jade” from the Bursa region of northwestern Türkiye has attracted attention as a gemstone; however, its geological characteristics and provenance have long remained uncertain. This short communication presents new field observations along with mineralogical and petrological data concerning the provenance, metamorphic evolution, and geoarchaeological relevance of this unique rock type. The rock occurs as loose boulders scattered across cultivated fields in the villages of Akpınar, Kocapınar, and Gedikören, where it was previously interpreted either as part of Neogene sedimentary successions or as a high-pressure metamorphic rock affected by contact metamorphism. Our detailed mapping and field observations suggest that the present distribution of the blocks reflects Quaternary reworking, whereas their primary source lies within the Late Cretaceous ophiolitic mélange of the Tavşanlı Zone. An apparently in situ exposure demonstrates a direct association between blueschist and felsic jadeite-bearing metavolcanic rocks. Mineral assemblages dominated by jadeite (40–60 vol. %), K-feldspar, albite, lawsonite, and relic aegirine, together with locally preserved volcanic microtextures and whole-rock geochemical signatures, indicate that the rocks represent blueschist-facies metatrachyte, locally grading into minor metaphonolite rather than true jadeitite jade formed by metasomatic processes. The purple to lavender coloration is largely restricted to fluid pathways. These rocks constitute a rare example of alkaline felsic volcanic protoliths metamorphosed under blueschist-facies conditions, most plausibly as part of an accreted seamount. Moreover, the occurrence of Neolithic polished stone tools produced from this rock type demonstrates its prehistoric exploitation and underscores its geoarchaeological importance.
The Syrian elephant (Elephas maximus asurus Deraniyagala, 1951) constitutes the extinct westernmost population of the Asian elephant and occupied parts of the Near East until the early first millennium BCE. Although historical, iconographic, and dental evidence for this population has been discussed extensively, its postcranial anatomy remains poorly documented. We present a revised osteological and morphometric study of cranial and postcranial remains recovered from the Late Bronze Age Gavur Lake Swamp assemblage (ca. 1650–1400 cal BCE) in Kahramanmaraş, southeastern Türkiye, during rescue excavations conducted in 2021 and 2022. The material derives from a natural swamp deposit rather than from an anthropogenic context such as an ivory workshop, ritual deposit, or ship cargo, and this context allows the skeletal anatomy to be assessed with better control over depositional and association data than is possible in many anthropogenic assemblages. We describe key craniodental, mandibular, and postcranial elements; provide osteometric data; and compare the Gavur Lake specimens with extant Elephas maximus and selected Quaternary elephantids. The assemblage represents at least four individuals, including a securely associated mature adult for which cranial and postcranial elements can be discussed together on the basis of excavation context. The postcranial material shows an overall Elephas-type articular pattern combined with marked robusticity. However, this robust construction is interpreted conservatively as an individual-level pattern until additional associated skeletons become available. The Gavur Lake material therefore provides an excavation-based postcranial reference set for late Holocene Elephas from southeastern Türkiye and offers an important comparative basis for future work on fragmentary elephant remains from Southwest Asia.
The tectonic framework of Northern Cyprus is presented in this study based on integrated fieldwork and paleoseismology. We identified multiple fault systems including the 214-km Dardere (Ovgos) Fault Zone (with seven segments), the Haspolat Transfer Fault, Mersinlik Fault, Yamaçköy Fault Zone, Boğazköy Fault, Alsancak Fault, and Geçitköy-Koruçam Fault Zone. Eleven paleoseismological trenches were excavated, with six yielding reliable results in terms of dating and stratigraphy. The results indicate recurrence intervals exceeding ~2500 years across different fault segments. The Dardere (Ovgos) Fault Zone shows the potential to generate earthquakes of up to Mw 7.80 with evidence of Holocene activity. The Haspolat Transfer Fault revealed f ive surface-rupturing earthquakes between 36100 ± 5500 BCE and 400 ± 300 CE. Our findings demonstrate that earthquake activity migrates across different faults through stress transfer mechanisms. The rapid tectonic uplift of Cyprus has resulted in accelerated erosion, complicating the preservation of Holocene sedimentary records in some locations. These results significantly enhance the understanding of regional seismic hazards and provide essential parameters for developing effective risk assessment frameworks for Northern Cyprus.
The Bolu region, situated along the western–central segment of the North Anatolian Fault Zone (NAFZ), is characterized by a complex fault architecture in which multiple overlapping strike-slip segments and associated subsurface structures accommodate active crustal deformation. Although the principal fault strands of the NAFZ have been well mapped, several clusters of seismicity are observed in areas without clear surface fault expression, indicating the presence of subsurface or poorly expressed fault zones. In this study, we integrated edge detection methods with a seismicity approach to delineate active and buried structural features across the Bolu region. Bouguer gravity anomalies derived from the WGM2012 model were analyzed using four gradient-based filters: the total horizontal derivative, tilt derivative, tilt angle of the horizontal gradient, and modified horizontal gradient amplitude filters. Among these, the MHGA technique produced the most coherent and noise-resistant results, allowing sharper identification of lateral density contrasts associated with fault-related discontinuities. Integration of MHGA results with seismic data revealed several previously unmapped, seismically active subsurface lineaments (numbered as 1–49), indicating a distributed deformation pattern extending beyond the main NAFZ strand. These findings provide new geophysical evidence for potential faults in the Bolu region and underscore the utility of potential field methods for refining active fault maps and improving seismic hazard assessments in northwestern Anatolia.
Upper Jurassic-Lower Cretaceous limestones of the Bilecik Formation are exposed near the village of D & uuml;mrek (Eski & scedil;ehir Province) within the Sakarya Zone. Mineralogical analyses reveal that these limestones are predominantly composed of calcite and include intraclasts, fossil shell fragments, ooids, and peloids, cemented by sparry and micritic calcite. The U/Th, Ni/Co, V/(V+Ni), V/ Cr, and Ce/Ce* ratios indicate that these carbonates were deposited in an oxic environment. Furthermore, the Mn/Sr ratios imply no diagenetic alteration, indicating preservation of the original geochemical signature. The PAAS-normalized REE+Y patterns of these limestones display depletion in light rare earth elements, a pronounced positive La anomaly (La/La* = 2.13-6.2), a distinct negative Ce anomaly (Ce/Ce* = 0.18-1.76), a slight positive Eu anomaly (Eu/Eu* = 1-1.41), and an enrichment in Y, all pointing to a well-oxygenated depositional environment with negligible detrital input. Stable isotope data show that the average delta 13C (V-PDB) value is 2.47%o, while the average delta 18O (V-PDB) value is-2.10%o. The delta 18O values display slight alteration with negative values, which are interpreted as evidence of early marine diagenesis. Based on these oxygen isotope values, the estimated paleotemperature during carbonate precipitation was approximately 26.15 degrees C. The calculated paleosalinity index (Z) of 131.40, obtained using the average delta 18O and delta 13C values, corroborates a marine origin for the carbonates. Furthermore, the paleoclimate proxy ratio & sum;(Fe + Mn + Cr + Ni + V + Co)/& sum;(Ca + Mg + Sr + Ba + K + Na) ranges between 0.087 and 0.09, indicative of an arid climate during limestone formation. The delta 13C (V-PDB) %o versus delta 18O (V-PDB) %o bivariate diagram confirms the marine character of the limestone.
This study investigates the seismic hazards of Bawean Island following a recent M6.5 earthquake using an integrated approach combining differential interferometric synthetic aperture radar (DInSAR) and horizontal-to-vertical spectral ratio (HVSR) methodologies. The DInSAR analysis revealed ground deformation characterized by subsidence up to 10 cm and uplift up to 8 cm, correlating with the region's strike-slip fault dynamics. HVSR analysis provided insights into site amplification effects, identifying zones with low Vs30 values (153.77-454.72 m/s), high amplification factors (A0), and elevated seismic vulnerability index values (Kg). The dominant frequency (f0) on Bawean Island ranges from 0.64 to 17.76 Hz, with most areas exhibiting low-frequency values below 2.5 Hz, indicating the prevalence of soft subsurface materials. Localized higher f0 values in the northwestern Tambak and southwestern Sangkapura areas suggest zones underlain by stiffer geological units. These results highlight the geological complexity and spatial variability of seismic hazards on the island. The applied dual-method approach proved effective in delineating high-risk zones and enhancing the predictive accuracy of seismic hazard assessments. The findings may contribute to the development of targeted mitigation strategies and provide a framework for similar studies in other geologically complex regions.
The Malatya Basin (MB) is a fault-controlled superimposed sedimentary basin situated in the SE of Anatolia, near and to the north of the East Anatolian Fault System (EAFS). The rock units ranging from the Permo-Carboniferous to the Upper Miocene form the basin's basement. The thickening of the Upper Cretaceous-Upper Miocene sequence toward the Malatya Fault (MF), the basin's northwestern boundary, indicates a dip-slip-dominated character for the MF and its control on the first-step sedimentation of the basin. The MF changes its character from dip-slip normal to the strike-slip in the Late Pliocene, and today presents a 1700-m left lateral offset, which points to a 0.56-mm/y slip rate and a recurrence period of 3571 years. It should be noted that there is no genetic relation to the Ovac & imath;k Fault (OF). The dip-slip normal & Ccedil;& ouml;& scedil;n & uuml;k Fault (& Ccedil;F), which is the basin's southern boundary and was reactivated during the 6 February earthquakes, led to the development of the region as a limnic environment during the second depositional step, as in the Pliocene. In the late Pliocene, the limnic basin turned into a fluvial regime. This fluvial system is the third step in the basin's depositional period. The & Ccedil;F later developed a strike-slip character and caused a left-lateral offset of the F & imath;rat River of about 4000 meters. The MF, as the basin's northwest boundary, was active from the beginning of the Pliocene with a left-lateral strike-slip character, causing earthquakes; however, it was not activated during the 6 February earthquakes. As for the & Ccedil;F, it began moving in a strike-slip mode in the late Pliocene, causing earthquakes at depths of 4-6 km. It is suggested that an earthquake could have occurred on the EAFS, which also activated this fault zone. This could have happened during the 6 February 2023 earthquakes.
A palaeofloristic study was carried out on Lower-Middle Miocene deposits of western T & uuml;rkiye (& Ccedil;an-Etili Basin). The sediments of the & Ccedil;an-Etili Basin, which were obtained from measured sections, were deposited in a continental environment. The palaeovegetation of the & Ccedil;an-Etili Basin (Kaz & imath;m O & gbreve;lak and Ke & ccedil;ia & gbreve;& imath;l & imath; successions) during the Early-Middle Miocene was mainly made up of evergreen and deciduous mixed forests (Castanea-Castanopsis, Cyrillaceae-Clethraceae, Engelhardia, Quercus evergreen-type, Quercus deciduous-type), riparian vegetation with high quantities ofAlnus and conifers such as Pinus haploxylon-type, Pinus diploxylon-type, and undifferentiated Pinaceae. The reconstructed palaeoclimate data from the palaeoflora (pollen and leaves) imply a warm and temperate climate, with mean annual temperatures of 13.8-21.1 degrees C and coldest-month temperatures of 5.5-13.5 degrees C. The average annual precipitation is around 1236 mm, indicating overall humidity. When reviewing previous quantitative palaeoclimate assessments from Western T & uuml;rkiye, no significant palaeoclimate variations along a north-south gradient were detected. Comparing data from the & Ccedil;an Etili Basin with previous studies from western T & uuml;rkiye, it can be inferred that the Aegean region was covered by dense woody vegetation. Moreover, the distribution of Picea suggests a landscape with moderate relief.
Accurate mapping of faults from 3D seismic volumes is critical for identifying structural traps, assessing reservoir compartmentalization, and guiding drilling decisions. This study evaluates how common seismic conditioning filters affect both the visual quality of a production Delft 3D poststack time-migrated volume and the outputs of two pretrained 3D CNN fault detectors: UNet3D and FaultNet. Seven filters were applied independently-AJAX, DeSmile, SimpleDenoise, Dip-Steered Median Filter (DSMF), Edge-Preserving Smoother (EPS), Fault Enhancement, and Ridge Enhancement-and results were inspected across inline, crossline, time-slice, and full-cube perspectives. The analysis is image-driven, supported by high-resolution comparison figures and view-specific interpretations. Filters that suppress incoherent noise while preserving dip-aligned continuity and edge gradients, particularly DSMF and EPS, produce the most interpretable inputs for UNet3D and yield thin, continuous fault traces with low internal clutter. SimpleDenoise provides conservative conditioning that improves signal-to-noise without creating artificial discontinuities, while DeSmile stabilizes outputs in areas affected by migration-smile curvature. In contrast, contrast-enhancing operators (AJAX and Fault/Ridge Enhancement) increase the detectability of weak lineaments but also broaden the apparent fault response and emphasize nonfault edges that require interpreter screening. Across all conditioning strategies, FaultNet produces a larger, higher-recall set of candidates that is useful for lead generation but requires curation, whereas UNet3D tends to return thinner, more connected masks when background noise is reduced, and edges are preserved. These findings provide practical guidance for selecting conditioning filters that improve the usability of pretrained CNN fault predictors on production seismic data.
Numerical temperature and fluid flow simulations were conducted using ANSYS Fluent to investigate the influence of porosity variations on the temperature distribution within the gas hydrate layer. The study was carried out in the Black Sea region, where the gas hydrate deposits are of particular interest due to their potential for energy resources. The simulations explored various porosity levels within the hydrate layer to observe their effect on thermal behavior and fluid dynamics. The results revealed that porosity plays a significant role in modulating the temperature distribution within the gas hydrate layer, with lower porosity models exhibiting higher temperatures compared to higher porosity models. These findings are consistent with the understanding that lower porosity environments tend to have reduced heat dissipation capabilities, leading to localized temperature increases. This study provides valuable insights into the thermal dynamics of gas hydrate systems and highlights the importance of porosity as a key factor in determining the stability and distribution of gas hydrates in marine environments.
The Karaburun deposit, hosted in greenschist facies metamorphic rocks, is a newly discovered giant volcanogenic massive sulfide (VMS) deposit in Anatolia and provides an exceptional natural laboratory for geophysical monitoring. The main ore body is less affected by metamorphism than the surrounding wall-rocks, where metamorphic and metasomatic processes formed pyritemagnetite-sericite-quartz assemblages that significantly influence geoelectrical properties. In this study, the geometry and extent of mineralization within geologically defined target zones were investigated using direct current resistivity and two-dimensional time-domain induced polarization (2D-TDIP) methods and the results were compared with the geology. A pole-dipole electrode array was employed in the Karaburun area, where a total of 55.5 km(2) of 2D-TDIP measurements were conducted along W-E-oriented lines. Zones characterized by high chargeability (>45 mV V-1) and low to moderate resistivity (45-160 Omega & centerdot;m) values were identified. The cause-and-effect relationships of these anomalies were evaluated by comparing them with the mineralization and drill core data, and the resistivity-IP responses associated with ore characteristics were classified accordingly. The Karaburun mineralization and its wall-rocks exhibit a heterogeneous structure, requiring careful interpretation of quantitative geophysical data, particularly in metamorphic terrains. The geoelectrical characteristics of the deposit differ from conventional expectations. In the metamorphosed pelitic-mafic-type Karaburun mineralization, high chargeability anomalies are primarily associated with phyllite and gossan effects rather than massive sulfide mineralization. Moreover, the presence of low resistivity anomalies within these zones tends to mask the true ore-bearing levels. Black shale precursor phyllites, together with oxidation zones and gossan formations, characteristically display relatively high chargeability coupled with low resistivity responses, whereas the main ore zones do not consistently exhibit high chargeability anomalies. Therefore, the typical high-chargeability/low-resistivity signature expected for VMS deposits does not fully apply to the Karaburun VMS; instead, generally low-resistivity anomalies better delineate this mineralization.
Shear-wave velocity (Vs) is one of the most critical parameters for determining geomechanical properties and basin overpressure. However, assessing Vs via techniques like core analysis requires considerable effort and expense. This study predicts Vs using several approaches and compares the accuracy levels of all models. For this objective, the multiple linear regression, multiple linear stepwise regression, support vector machine, and least-squares boost (LSBoost) methodologies were selected. The six well-logging data inputs of density (RHOB), gamma-ray (GR), deep resistivity (ILD), acoustic wave velocity (Vp), shale volume (VCL), and water saturation (SW) were selected as effective variables, whereas Vs was regarded as the output. The model was developed using data from the RCW-1 well and evaluated through 5-fold cross-validation and independent blind cross-well validation. The LSBoost model demonstrated robust and stable in-well performance, achieving a mean coefficient of determination (R2) of 0.958 +/- 0.003 and root mean square error (RMSE) of 56.48 +/- 1.58 m/s, indicating effective learning without evidence of overfitting. Feature importance and Spearman rank correlation analyses consistently identified ILD and Vp as the most influential predictors, confirming the presence of nonlinear monotonic relationships between the input logs and Vs. However, blind application of the RCW-1-trained model to the independent RCW-2 well resulted in reduced predictive accuracy (R2 = 0.266, RMSE = 287.95 m/s), reflecting geological and petrophysical domain shifts between wells rather than model inadequacy. Comparisons with empirical Castagna and Greenberg-Castagna correlations showed that while the empirical models provided relatively stable baseline predictions across wells, LSBoost significantly outperformed them within a consistent geological domain. These results highlight the potential of LSBoost for accurate Vs prediction when representative training data are available and emphasize the importance of multiwell datasets to improve cross-well generalization.
Hyperspectral image (HSI) classification is of critical importance in many fields including agriculture, geology, environmental monitoring, and urban planning. In recent years, many researchers have utilized deep neural networks (DNNs), known for their high performance in the classification of HSIs. When 2-D/3-D convolutional neural networks are used in HSI classification, filters applied using input patches typically larger than 11 & times; 11. This allows spectral and spatial features to be evaluated together. However, this combination creates several problems. Because HSIs have low spatial resolution, they often do not contain strong texture details. Furthermore, features with little relevance to classification make the feature vectors spread out in the input space. More importantly, when large input patches and high sampling rates are used, the training set may implicitly include the test data. To overcome these issues, a new 1-D DNN framework is proposed in this study instead of 2-D DNNs. A novel deep learning model focusing on the identification of features is applied. Features related to the images are extracted with fully connected neural networks trained with Walsh vectors and the classification process is carried out with a minimum distance network. With spectral data alone, the proposed 1-D DNN model achieves average accuracy of 97% on the Indian Pines, Salinas, Pavia Centre, Pavia University, and Botswana datasets. It is observed that, compared to 2-D DNNs, the proposed 1-D DNN achieves high accuracy while avoiding overlap problems and unnecessary complexity, making it a simpler and more reliable choice for HSI classification.
As global energy demand rises, unconventional gas resources, particularly tight gas reservoirs, have become increasingly important for future energy supply. Located in the southwestern Ordos Basin, the Qingyang gas field is a newly discovered deep tight-gas field with proven geological reserves exceeding 31.8 & times; 109 m3 and has become a strategic focus for deep-gas exploration in China. Despite rapid appraisal that delineated several stable gas-bearing zones, a comprehensive understanding of the sedimentary architecture, diagenetic transformation, and enrichment mechanisms of high-quality reservoirs in the Permian Shanxi Formation remains incomplete. Focusing on the Shan 1 Member (hereafter referred to as Shan 1), we integrate core description, well-log interpretation, petrographic analysis of casting thin sections, scanning electron microscopy, and production-test data to classify sedimentary microfacies, quantify pore-structure attributes, establish diagenetic sequences, and interpret the spatial configuration of low-amplitude structures. The sandstones were deposited in a shallow-water meandering river delta system exhibiting pronounced lateral zonation and vertical stacking, which are common characteristics of meandering river delta front environments. Subaqueous distributary channels and mouth bars constitute the dominant reservoir microfacies. Reservoir lithology is dominated by medium-to fine-grained feldspathic lithic sandstones in which intergranular and intragranular dissolution pores impart marked heterogeneity. Reservoir quality is governed by the coupled evolution of compaction, cementation, and dissolution, with diagenetic timing exerting first-order control. Highenergy, laterally persistent sandbodies provide favorable primary conditions, while late-stage structural inversion governs sandbody amalgamation and migration. Low-amplitude structures further modulate the distribution of productive zones, with high-yield wells preferentially occurring on structural highs and in sandbody overlap areas. These results refine the genetic model for tight-sandstone reservoir formation in Shan 1 and provide geological guidance for high-resolution prediction and deployment of favorable targets in deep-gas exploration.
Accurate lithological mapping requires selecting the appropriate remote sensing data and classification methods. This study evaluates the performance of four satellite datasets-Landsat 8 OLI, Sentinel-2A, ASTER, and Hyperion EO-1-using three spectral classification techniques: Matched Filtering (MF), Spectral Angle Mapper (SAM), and Spectral Information Divergence (SID). The study area is located between the Zara and Koyulhisar districts in eastern T & uuml;rkiye and comprises diverse lithological units. A total of 49 The results indicate that MF consistently outperformed the other methods, achieving the highest accuracy with Landsat 8 (Kappa = 94.2%). ASTER data demonstrated strong capability in distinguishing lithologies with subtle spectral differences, particularly due to its SWIR bands. Meanwhile, Sentinel-2A provided improved spatial delineation. Despite its high spectral resolution, Hyperion showed limited performance in separating spectrally similar units. Misclassification was primarily associated with lithologies that had similar The results demonstrate the efficacy of MF in conjunction with multispectral data for lithological mapping and underscore the significance of selecting suitable data-method combinations in geologically complex regions.
The objective of this study was to identify and assess shallow landslide hazard in both spatial and temporal terms within the boundaries of Be & scedil;ikd & uuml;z & uuml; District in northeastern T & uuml;rkiye. The workflow was initiated with the development of a detailed multitemporal mass-movement inventory map derived from satellite imagery provided on the Google Earth platform,1 covering the period between 2000 and 2018. Inventory mapping was complemented by extensive field verification campaigns to identify discrepancies, confirm spatial accuracy, and document additional morphological details that could not be detected from imagery alone. A 10-m spatial resolution digital elevation model (DEM) was generated from 1:25,000-scale digital topographic maps produced by the General Directorate of Mapping of T & uuml;rkiye. From this DEM, a suite of secondary topographic derivatives including slope, aspect, plan curvature, profile curvature, stream power index, and topographic wetness index were computed within a geographic information system environment. These preparatory and morphometric parameters formed the basis for the subsequent susceptibility modeling. To determine the temporal probability of rainfall-induced landslides, precipitation datasets acquired from the Turkish State Meteorological Service2 were statistically analyzed. The temporal component was further supported by correlating mapped landslide dates with reports from the Disaster and Emergency Management Presidency, local interviews, and regional news archives, enabling the identification of rainfall thresholds and recurrence characteristics. Spatial probability was evaluated through areal size-frequency analyses of shallow landslides, combined with a probabilistic logistic regression approach to assess susceptibility. Following the probabilistic framework, potential landslide hazard maps were produced for return periods of 1, 2, 5, 10, and 20 years, incorporating both temporal and spatial probabilities as well as magnitude-dependent thresholds derived from the mapped landslide areas. By integrating inventory data, DEM-derived terrain parameters, rainfall-triggered temporal modeling, and frequency-area distribution analyses, we present a robust and comprehensive methodology for quantifying shallow landslide in the study region. The results provide valuable insights for land-use planning, regional hazard mitigation, and engineering applications in one of T & uuml;rkiye's most landslide-prone regions.
The 20 March 2019 Ac & imath;payam earthquake (Mw 5.7) offers a valuable opportunity to examine the complex seismotectonic behavior of the Fethiye-Burdur Fault Zone (FBFZ), a transtensional structure in southwestern T & uuml;rkiye. This study integrates field observations and focal mechanism data with differential interferometric synthetic aperture radar (DInSAR) analysis to reassess the geometry of the causative fault. In contrast to previously proposed northeast-dipping blind fault models, the data obtained in this study indicate a southwest-dipping listric normal-fault system centered on the Yenik & ouml;y Fault, projecting beneath alluvial cover. Vertical displacement maps from Sentinel-1 show coseismic subsidence up to 5.8 cm and broader postseismic deformation. The deformation asymmetry, surface cracks, vertical displacement zones, and morphotectonic lineaments collectively support the continuity of a shallow fault. Aftershock patterns and kinematic indicators corroborate the activation of a segmented fault network, while the deformation field highlights the roles of stress transfer and viscoelastic relaxation in shaping postseismic responses. Additionally, historical seismicity suggests a recurrence interval of approximately 122 years for destructive events, whereas previous paleoseismological studies identify three Holocene surface ruptures with an average recurrence of about 350 years, highlighting both short-and long-term earthquake cycles. The 2019 rupture may reflect strain transfer from the most recent paleo-event to adjacent segments, reinforcing the seismogenic significance of the Yenik & ouml;y fault despite the absence of a clear surface rupture. DInSAR-derived deformation and focal mechanism patterns align with a steeply dipping listric normal-fault whose curvature explains the lack of a clear surface trace. These findings underscore the importance of integrating geodetic, field-based, and historical perspectives to refine seismic hazard assessments in Ac & imath;payam and comparable extensional settings.
This study documents and interprets bioerosion and encrustation traces on Upper Cretaceous scleractinian corals from the Hajajah Member of the Aruma Formation in northern Khashm Buwaibiyat, central Saudi Arabia. Fieldwork in 2023 and 2024 involved detailed bed-by-bed stratigraphic logging, ichnological assessment, and fossil collection across marl and limestone units. A total of 213 coral specimens with bioerosional features were analyzed, leading to the identification of 10 ichnospecies across 5 ichnogenera, including Gastrochaenolites, Entobia, Caulostrepsis, Rogerella, and Labyrintichnus. These traces reflect a range of ethological categories, primarily domichnia, indicating permanent dwelling structures by polychaetes, sponges, bivalves, barnacles, and crustaceans. The Hajajah Member records a shallow marine back reef to shoal environment, periodically interrupted by high-energy events. Bioerosional features suggest ecologically complex settings with abundant hard substrates, frequent colonization, and biologically mediated sediment modification. This work contributes to the ichnological record of the region. It underscores the importance of bioerosion as a tool for reconstructing paleoenvironmental conditions in the Late Cretaceous carbonate settings of the Arabian Plate.
The karst-type bauxite deposits located in southwestern T & uuml;rkiye represent the most significant bauxite resources in the country. Surrounding these bauxite deposits are widespread red soil deposits of varying sizes, developed over lithologically diverse rocks. This study aims to investigate the origin of these red soils, which were examined in two distinct groups based on their spatial relationship to the underlying geology. The first group of red soils is found on or within the fractures of karstic limestones, while the second group is primarily located in proximity to ophiolitic rocks. The investigation focused on the physical properties, as well as the mineralogical and chemical compositions, of these soils. Although both groups display partially similar mineralogical compositions and major element contents, notable differences were observed in their trace element, and especially rare earth element (REE), concentrations. The total REE contents range from 206 to 433 ppm in the first group and 853 to 4487 ppm in the second group. No significant correlations were identified between REE concentrations and either trace or major element oxides. The Ce anomalies is slightly positive (mean 1.0, std=0.18) in the most first group samples, with one second group sample at 1.07, while remaining samples exhibited a strong negative anomaly (mean 0.40, std=0.40). A positive Eu anomaly was observed in the first group (1.11), while no anomaly was found in the second group (0.99). These variations, including the wide range in REE contents and the absence of correlation with other geochemical parameters, suggest that the red soils may have different origins. The PASS-normalized REE and immobile element trends of the first group are partially aligned with the trends observed in schists, whereas the second group displays a markedly different pattern-largely parallel to that of ophiolitic rocks, and showing greater enrichment than all rock types examined in the study area.
The magnesite deposit of the Edige region in Ankara-Elmada & gbreve; District of T & uuml;rkiye is hosted in serpentinite/serpentinized ultramafic rocks, which are mainly harzburgite and dunite. Mineralogical and petrographic studies have shown that ultramafic rocks are composed of serpentine, olivine, and pyroxene with serpentinization preceding magnesite formation. The X-ray diffraction results reveal that dolomite, quartz, calcite, and clay minerals are the main minerals in magnesite samples from serpentinite/serpentinized ultramafic units. Olivine, pyroxene, serpentine, chromite, and iron oxide minerals are also present. Scanning electron microscopy and energy dispersive spectrometry results show that magnesite in rhombohedral and cryptocrystalline forms is the dominant mineral accompanied by dolomite and quartz. The geochemical data show high MgO values between 33.3% and 37.2% and SiO2 values between 37.3% and 42.9%, indicating peridotite characteristics. The CaO values are very low, with an average of 1.01%, and the Al2O3 values are between 0.2% and 1.8%. These results also suggest that peridotite rocks formed through partial melting of a depleted mantle source. Stable carbon (delta 13C) and oxygen (delta 18O) isotope data indicate magnesite formation at shallow depths through low-temperature diagenetic processes, with delta 13C values between-13.62%o and-10.54%o Vienna Pee Dee Belemnite (VPDB) and delta 18O values between-3.51%o and-2.01%o VPDB corresponding to 27.29%o to 28.84%o Vienna Standard Mean Ocean Water. These data suggest that the carbon came from organic-rich sediments and fluids influenced by meteoric waters.
