Late quaternary shell deposits in Northwestern Sri Lanka: New data on chronology, stratigraphy, and contents

Groundwater exploration in arid regions of the Eastern Desert of Egypt requires an integrated understanding of the structural, geomorphic, and subsurface controls governing recharge and storage. This study presents a GIS-based groundwater potentiality model for a structurally complex rift-related zone along the southern Esh El Mellaha Block, between the Gulf of Suez and northern Red Sea. Sixteen topographical, meteorological, hydrological, and surface geological factors were systematically integrated with particular magnetic basement-depth modeling and subsurface fault architecture, which were weighted using the Analytical Hierarchy Process (AHP). Results demonstrate that regional tectonic configuration and structural geometry, rather than surface geomorphic factors alone, exert the primary control on groundwater distribution. High-potential zones are concentrated within major structural lows, including the Tarboul syncline, West Hurghada trough, and El Gouna fan system, where thick Quaternary deposits and enhanced infiltration prevail. The ENE-trending Bali Shear Zone acts as a key conduit for focused recharge by enhancing fracture permeability and linking the Gulf of Suez and Red Sea structural domains. Model validation yielded an AUC of 0.80, with balanced sensitivity and specificity (0.74), indicating reliable predictive performance. Single parameter sensitivity analysis confirms the robustness of the model and indicates that structural and geological factors exert the strongest control on groundwater potential distribution. The study emphasizes the role of structural architecture in groundwater assessment and supports future sustainable water-resource development in arid extensional tectonic settings.

Over the past decade, road and civil construction activities in Ukraine have intensified significantly, with a considerable number of projects being implemented in areas characterized by unfavorable engineering and geological conditions. Construction is increasingly carried out on weak and collapsible soils, including loess deposits, organic-mineral soils, andtechnogenically altered formations that exhibit reduced strength and instability under changes in moisture regime, salt composition, and seasonal effects. Loess soils, which occupy a dominant position among Quaternary deposits in Ukraine, are distinguished by high porosity and a pronounced loss of structural strength when wetted, leading to sudden collapsible deformations and uneven settlement of foundations.The paper analyzes the engineering characteristics of collapsible loess soils, the mechanisms of deformation development under loading and wetting, and the main indicators used to assess collapsibility, including relative collapsibility, critical collapsible pressure, and threshold moisture content. A systematic review of modern methods for improving the properties of weak soil foundations is presented, covering structural, physical-mechanical, and physico-chemical approaches.Special attention is paid to injection-based soil stabilization technologies, such as jet grouting, deep soil mixing, chemical grouting, electrochemical stabilization, and innovative bio-cementation methods. These techniques allow the formation of artificial structural bonds between soil particles, leading to increased bearing capacity, reduced compressibility, and improved water resistance without large-scale soil excavation. The analysis demonstrates that injection stabilization methods are among the most effective and versatile solutions for mitigating collapsibility and ensuring the long-term reliability and durability of foundations in road and civil engineering projects.

Research subject . Mineral assemblages of native gold from carbonatites and Quaternary deposits of the Guli massif (Maimecha–Kotui province, Russia), which are associated with complex gold–iridium–osmium placer deposits. Aim. To identify mineral assemblages and variations in the chemical and Cu-isotopic composition of native gold from calcite– dolomite carbonatite of the Southern carbonatite stock and Quaternary deposits of the Gule River, draining carbonatites of the Guli massif. Methods . The chemical composition of native gold was studied using a CAMECA SX 100 electron microprobe analyzer. The analytical technique for determining δ 65 Cu included dissolving gold samples in a mixture of HCl and HNO 3 , selective chromatographic separation of Cu from solution, followed by determination of the 65 Cu/ 63 Cu value using a ThermoFisher Neptune Plus MC-ICP mass spectrometer. Results . The analyzed samples are represented by single-phase and polyphase mineral assemblages of native gold within homogeneous and heterogeneous grains, which consist of high-fineness gold, electrum, natural Au–Ag–Cu alloys, tetra-auricupride, and auricupride. The first Cu-isotope data for gold minerals from calcite-dolomite carbonatite of the Guli massif and Quaternary deposits of the Gule River revealed identical, within analytical uncertainty, average δ 65 Cu values (−0.49 ± 0.08‰ (n = 3) and −0.30 ± 0.30‰ (n = 8), respectively). Conclusions . The observed features of the mineral assemblages and the chemical composition of native gold from calcite–dolomite carbonatites show a close similarity to those of placer deposits of the Gule River, located near the Southern Carbonatite Stock. Copper isotopic data for both primary and placer gold are consistent within analytical uncertainty, suggesting a common juvenile source. It is proposed that the principal bedrock sources of gold were rocks of the Maimecha–Kotui ijolite–carbonatite complex.

Biostratigraphy is a fundamental tool for age-calibrating marine sediments and enabling palaeoceanographic reconstructions. However, establishing age control in marine sediments of the Arctic Ocean is challenging, due to low micro- and nannofossil abundances, discontinuous occurrences across glacial and interglacial periods, as well as spatial and temporal variations in carbonate preservation. Gephyrocapsa huxleyi is a globally distributed coccolithophore whose first occurrence at ca 290 ka is widely used to date Quaternary marine sediments. Yet, its initial appearance and stratigraphic range in the Arctic Ocean are debated. Here, we present the first combined seda DNA-nannofossil approach to trace the occurrence of G. huxleyi throughout three sediment cores from the Lomonosov Ridge recovered during the Arctic Ocean 2016 expedition on icebreaker Oden. Sed aDNA was extracted from 87 samples spanning key lithological boundaries. Following shotgun sequencing, the presence of G. huxleyi was assessed using three independent bioinformatic tools Kraken2, BWA and BLAST. These results were integrated with lithological data and Gephyrocapsa nannofossil assemblages to evaluate the potential of palaeogenomics as a biostratigraphic tool in the Arctic that could potentially overcome the limitations of conventional nannofossil-based approaches. Although we found broadly overlapping seda DNA and nannofossil results, key discrepancies and methodological limitations do not allow us to confidently identify the first occurrence of G. huxleyi in the studied sequences. We discuss both the potential and the challenges of seda DNA as a complementary biostratigraphic tool to improve age control of Arctic marine sediments. • We present a novel combined seda DNA-nannofossil approach to trace the occurrence of the key biostratigraphic marker Gephyrocapsa huxleyi in Arctic Ocean sediments. • Seda DNA from 87 samples, spanning and extending below the established biostratigraphic range of G. huxleyi, is analyzed together with nannofossil assemblages. • Broadly overlapping seda DNA and nannofossil results are revealed, but discrepancies and methodological limitations prevent confident placement of the first occurrence of G. huxleyi.

A-type granitoids as a major source of indoor radon and gamma radiation: Insights from the Punilla valley (Argentina).

The ∼430-km-long, east−west-striking northern West Qinling fault is seismically active and serves as a critical tectonic bridge, facilitating strain transfer between the contractional northeastern margin of the Tibetan Plateau and the extensional North China Craton. Using high-resolution Satellite for Earth Observation (SPOT) imagery in combination with field observations, this study analyzes geomorphic markers, geologic evidence, and geodetic constraints on left-lateral slip deformation along this structurally complex fault system and examines strain transfer between strike-slip faults in Northeast Tibet. The western segment (∼120 km) exhibits diagnostic left-lateral geomorphic signatures, with four distinct classes of river channel offsets measuring 3500−4100 m, 340−430 m, 75−130 m, and ∼35 m. These cumulative displacements contrast sharply with the subdued morphology along the central segment (∼160 km), where Neogene basin deformation records a Pliocene compressional phase, as evidenced by an angular unconformity between Quaternary deposits and the underlying Neogene red strata. The eastern segment (∼150 km) displays brittle deformation textures, including fault breccias and ultracataclasites, but lacks evidence of significant Holocene activity. Cumulative offsets (∼4000 m) along the western segment align with a long-term low slip rate of 0.8−1.7 mm/yr, assuming deformation initiated at 5 Ma or 2.4 Ma. GPS velocity field corroborates a slow slip rate, showing ∼1 mm/yr sinistral motion in the west and negligible activity in the east. Regionally, the northern West Qinling fault and active faults in West Qinling form a structural continuation of the active East Kunlun sinistral fault system and extend eastward through the southern Weihe graben into East Qinling. Slip transfer occurred through fault bending and bifurcation. By integrating surface deformation with the subsurface velocity structure, we propose a layered-flow model wherein the eastward extrusion of the materials from beneath the Tibetan Plateau through the Qinling belt induces mechanical decoupling between upper-mantle flow and brittle crustal deformation. This vertically partitioned rheology could explain the observed disparity between surface fault kinematics and subsurface mass transport dynamics.

Abstract The 28 March 2025 Mw 7.7 Myanmar earthquake produced moderate-to-strong, long-period ground shaking across Thailand and offers a rare opportunity to evaluate nationwide site-response characteristics. Strong-motion data from 77 Thai Meteorological Department’s seismic stations were analyzed using horizontal-to-vertical spectral ratio to determine fundamental resonance period (T0) and amplification (H/Vmax). Each geological province shows unique signatures in the ground-motion spectrum observed across the country. The northern intermontane basins exhibit a dual-mode resonance pattern (T0≈0.7–2.5 s) and short-period peaks (T0<0.6 s) caused by both shallow-to-moderate alluvial sediments. The western fault valleys show sharp, short-period peaks caused by thin alluvial layers over hard bedrock, whereas the northeastern plateau shows both short-period peaks due to thin sediments and also behaves as a stable reference domain with flat, rocklike H/V curves. The central Thailand rift basin reveals sharp, short-period peaks (T0≈0.2–0.8 s) that indicate the presence of shallow-to-moderately deep sedimentary layers beneath the sites. The Bangkok basin shows broad, low-frequency amplification (T0≈4–7 s), a direct result of deep soft Quaternary sediments. The southern rift basins and coastal plains show mixed characteristics: sharp, short-period peaks (T0=0.2–0.5 s) and dual or multipeaked H/V spectra (T0=1–1.9 s), due to thin to moderate-to-thin sediment covers. For the first time, this study identifies long-period resonance (T0>4 s) in multiple provincial basins beyond Bangkok (Chiang Mai, Lampang, Phrae, Pathum Thani, and Surat Thani provinces), indicating that deep sedimentary structures across Thailand can amplify long-period seismic waves that can affect tall and long structures such as high-rise buildings, bridges, and elevated expressways. These results provide the first observation for a countrywide frequency-dependent site response from a real earthquake event, which indicates that both short- and long-period site effects are equally important for seismic hazard evaluation in Thailand.

This paper presents a comprehensive field-based analysis of the stratigraphic successions and depositional environments in the Jabal Al-Hasawna and Wadi Ash-Shatti regions of southwestern Libya. Based on a detailed seven-day geological field excursion, the study documents a chronological sequence ranging from the Precambrian basement to Quaternary deposits, with a primary focus on the Paleozoic strata. Key formations investigated include the Al-Hasawna (Late Cambrian), Tanazzuft (Silurian), and the Devonian Awaynat Wanin Group (Bir Al-Qasr, Edri, Quttah, Dabdab, Tarut, and Ashkidah formations). The field data reveal a dynamic geological history characterized by significant transgressive-regressive cycles. The transition from the stable cratonic basement to the fluviodeltaic Al-Hasawna Formation is marked by a profound nonconformity. Subsequent Silurian marine transgressions deposited the graptolitic shales of the Tanazzuft Formation. The Devonian successions are notably characterized by coarsening-upward progradational cycles, intense bioturbation (dominated by Skolithos and Tigillites ichnofacies), and the widespread occurrence of ferruginous oolitic sandstones, indicating storm-dominated, shallow marine to restricted lagoonal environments. By integrating lithological, ichnological, and structural field observations across multiple sites, this study provides a unified model of the region's stratigraphic evolution, highlighting the complex interplay between sea-level fluctuations, sediment supply, and tectonic stability.

Abstract The southwestern Atlantic margin plays a crucial role in understanding ocean circulation, with the Brazil Current (BC) driving surface flow and various water masses (TW, SACW, AAIW, UCDW, NADW, LCDW) influencing different depths. The Santos Basin, a marginal basin formed following the breakup of Gondwana, remains understudied with respect to late Quaternary sedimentary processes, and the recent literature offers conflicting interpretations of sediment sources and depositional processes. Additionally, radiocarbon data for this region are scarce, and calibration uncertainties and regional reservoir effects have limited previous studies. This study compiles a comprehensive radiocarbon dataset (264 datings from 70 sediment cores) for the upper to middle slope of the Santos Basin (120–2000 mbsl), combining published and unpublished data (69 new ages). Previously published ages were recalibrated using Marine20 and SHCal20 curves, applying a regional ΔR correction. The dataset, showing minimal age inversions, provides a robust foundation for future research on late Quaternary sedimentary and paleoenvironmental dynamics in the southwestern Atlantic.

Short-period dense linear array ambient noise tomography of shallow crustal structure across the Haichenghe fault zone, China

Sedimentological evidence of lagoon-marine transitions in the Quaternary deposits of Dhar Eddoum (Atlantic Coast, Morocco)

The Bahariya Oasis in Egypt’s Western Desert faces critical water security challenges due to intensive groundwater exploitation and limited renewable recharge. To address this challenge, this study integrates a GIS-AHP model for the first time in the Bahariya area and incorporates high-resolution aeromagnetic data to enhance the prediction of groundwater potential zones. Nine groundwater-controlling thematic layers were compiled from multi-source datasets, classified, and weighted using the AHP model: structural geology (lineament density), terrain (slope), hydrology (drainage density and rainfall), hydrogeology (lithology and soil moisture), land-surface conditions (NDVI and LU/LC), and the RTP aeromagnetic signal. The resulting groundwater potential map delineates coherent “very-high” potential corridors concentrated in the southern and southeastern sectors, where high lineament density, low-relief topography, and permeable Quaternary alluvial deposits coincide and correlate with known productive wells, suggesting favorable conditions for enhanced recharge and storage. Potential patterns also show strong spatial correlation with the drainage network and mapped structural trends. Model validation against well occurrences yields an AUC of 93.4%, indicating excellent predictive accuracy. Aeromagnetic interpretation further resolves the subsurface structural architecture and constrains the basement configuration, revealing a marked deepening of the basement toward the south and southeast. This is where a thick sedimentary cover suggests enhanced groundwater storage potential, providing additional support for the groundwater potential zoning results. This integrated workflow offers a robust tool for groundwater prediction and planning, with direct utility for prioritizing drilling locations and supporting sustainable water resources planning in arid environments.

ABSTRACT Mammals’ remains are commonly and abundantly retrieved from Quaternary deposits in Brazil. However, small-sized mammals are rarely studied in detail, despite their great potential for biodiversity dynamics studies and paleoenvironmental inferences. In northeastern Brazil, there are very few Quaternary records of these organisms, especially for some states such as Ceará. This study aims at partially filling this gap, by describing Holocene remains of Didelphimorphia, Rodentia, and Chiroptera, retrieved in subsurface excavation at the Gruta do Urso Fóssil, Parque Nacional de Ubajara, State of Ceará. The specimens come from nine artificial layers of 10 cm each, some of which were dated by thermoluminescence and optically stimulated luminescence, resulting in a time interval ranging from 7000 ± 1,000 to 8450 ± 960 years BP. The unearthed mammal fauna, mostly isolated teeth and fragmented bones, are composed of (i) five species of didelphimorphian marsupials (Didelphis albiventris, D. marsupialis, Metachirus sp. Monodelphis cf. domestica, and Gracilinanus agilis); (ii) five caviomorphs rodents (Kerodon rupestris, Cuniculus sp. cf. Dasyprocta sp. Proechimys sp. and Thrichomys cf. laurentius); (iii) three sigmodontine rodents (Hylaeamys cf. megacephalus, Calomys sp. and Rhipidomys cearanus); (iv) and six chiropterans (Furipterus horrens, Carollia perspicillata, Micronycterinae indet., Chrotopterus auritus, Phyllostomus hastatus, and Artibeus sp.). Except for Proechimys, all genera still currently occur in the area. This mammal assemblage suggests wet environmental conditions at the ‘Brejo de Altitude’ in the early Holocene, similar to the current ones.

Abstract Shallow S-wave velocity (V S ) structures in Tainan City, Taiwan, were characterized using microtremor array data for 18 sites compiled by Huang et al. (Terr Atmos Ocean Sci 35:20, 2024). Theoretical transfer functions were calculated at the surface relative to six depth formations (50, 100, 200, 400, 700, and 1,000 m) and five V S formations (350, 550, 750, 1,000, and 1,500 m/s) by using the Haskell method. Higher predominant frequencies were observed in the Tainan tableland (central part of the study area), whereas lower predominant frequencies were observed in the Anping plain (western part of the study area). If the S-wave velocity in the Tertiary basement is 1,500 m/s, the predominant frequencies of Quaternary sediments range from approximately 0.2 Hz (in the Anping plain) to 0.65 Hz (in the Tainan tableland), decreasing radially from the central to surrounding sites. We compared the horizontal-to-vertical (H/V) ratios of microtremors with the predominant frequencies calculated using theoretical transfer functions. Our findings suggest that site amplifications derived from H/V ratios are primarily attributable to alluvium from the surface to depths of 50–100 m at most sites. For sites in the Tainan tableland, amplifications derived from H/V ratios are primarily attributable to alluvium between the surface and the formation of V S = 550–750 m/s. For sites in the Anping plain and the Dawan lowland, amplifications are primarily attributable to alluvium between the surface and the formation of V S = 350–550 m/s.

The small mammal fauna (Marsupialia and Rodentia) from Araras ravine, a Quaternary deposit in northeastern Brazil, and their paleoclimatic significance for South American paleoenvironments

Quaternary cold-climate hillslope processes, landforms and deposits in the Polish medium-altitude mountains – state-of-the-art and research perspectives

Deciphering silicate weathering archives registered in the late Quaternary sediments of Asian continent marginal seas

Accurate 3D geological modeling of Quaternary deposits is crucial due to their inherently heterogeneous structures, such as clay-silt lenses, channels, and slope deposits. These small- to medium-scale features significantly influence geological engineering and resource evaluation but are challenging to reconstruct with limited borehole data. In this study, a synthetic explicit 3D geological reference model containing typical Quaternary structures was constructed using GOCAD®. Borehole data were systematically extracted at varying densities using both regular and irregular sampling layouts and used to build implicit models through Leapfrog Geo™ software. Quantitative comparisons between the explicit and implicit models were conducted using Jaccard distance and normalized City-Block Distance metrics. The results demonstrate that as borehole density increases, the accuracy of the implicit models improves significantly, particularly in capturing small-scale structures such as lenses and narrow channels. Meanwhile, the influence of sampling layout remains comparatively minor. The study identifies a critical borehole density threshold required to reliably reconstruct complex geological features, providing quantitative measures for optimizing borehole exploration strategies in Quaternary geological settings.

Abstract The Argoub Kemellal dome, located south of Oum El Bouaghi in northeastern Algeria, preserves a rich sedimentary archive documenting the paleoenvironmental evolution of the Neogene-Quaternary period. This study aims to reconstruct the paleogeographic development of the region by examining the interplay between sedimentary processes and environmental changes, particularly the transition from fluvial to lacustrine conditions. A multidisciplinary approach combining petrographic and sedimentological analyses was applied. Techniques included granulometric and calcimetric measurements, thin-section petrography, and both morphoscopic and scanning electron microscope (SEM) studies of quartz grains. The geological sequence comprises Miocene-aged detrital deposits overlain by Pliocene to Quaternary carbonate formations. Sedimentary formations document a transition from high-energy fluvial conditions to calmer lacustrine environments, driven by climatic change. Notably, calcium carbonate (CaCO 3 ) content increases upward from 13% at the base to 57% at the top, highlighting the shift toward carbonate-dominated lacustrine sedimentation. These results illustrate how climate forcing shaped sedimentary environments over time and contribute to reconstructing the Neogene-Quaternary paleogeography of the studied region. The finding underscores the value of continental deposits as sensitive geological archives of past environmental and climatic conditions.