Earth and Environmental Sciences

Abstract The Cretaceous/Paleogene (K/Pg) Chicxulub impact produced globally synchronous enrichments of highly siderophile elements (HSEs) and a pronounced decline in marine osmium isotope ratios ( 187 Os/ 188 Os), forming a key geochemical marker of the boundary. However, precise identification of the K/Pg boundary remains challenging in extensive pelagic regions dominated by deep‐sea red clay, where calcareous and/or siliceous microfossils are poorly preserved. Here we identify the K/Pg boundary in a pelagic clay sequence from piston core KR13‐02 PC05 recovered near Minamitorishima Island in the western Pacific Ocean using HSE concentrations and Os isotope stratigraphy, supported by ichthyolith biostratigraphy and magnetostratigraphy. A distinct Ir enrichment (up to ∼16 ppb) coincides with the most unradiogenic 187 Os/ 188 Os value (∼0.14) at ∼9.95 mbsf, defining a geochemical horizon consistent with the global signature of the Chicxulub impact. Polarity chrons spanning C29n–C30n and ichthyolith assemblages support the placement of the K/Pg boundary and provide a robust chronological framework. Above the boundary, 187 Os/ 188 Os ratios remain persistently unradiogenic over a stratigraphic interval corresponding to several hundred thousand years. This prolonged signal reflects the integrated effects of extremely low sedimentation rates, sediment reworking by bioturbation, and background extraterrestrial dust inputs. These results demonstrate that sedimentary Os isotope records in low‐accumulation pelagic clay do not necessarily represent a simple archive of contemporaneous seawater composition. Instead, depositional and diagenetic processes can substantially modify post‐impact isotopic signals. Our findings highlight the necessity of multi‐proxy chronological control and careful geochemical screening when reconstructing oceanic responses to the K/Pg impact on microfossil‐poor pelagic environments.

Abstract The interaction between the Tethyan and Paleo‐Pacific subduction systems in Southeast Asia since the Paleozoic is still poorly understood. Hainan Island and Borneo, located near the junction of the Tethyan and Paleo‐Pacific domains, provide the critical regions for understanding the dynamic processes and interaction between the two tectonic domains. Using new and published zircon U‐Pb‐Hf isotopes, and the detrital zircon Eu/Eu* data, we evaluate crustal evolution and the relative crustal‐thickness variations in both regions. The data sets indicate broadly synchronous intervals of reduced apparent crustal thickness inferred from Eu/Eu* at 440–410 Ma, 370–350 Ma, 270–220 Ma and 160–140 Ma, together with largely negative ε Hf ( t ) values through the Paleozoic‐Triassic, which characterized by the mixed mantle‐derived material and older crustal components, probably associated with the Paleo‐Pacific subduction. Jurassic–Cretaceous zircons from Borneo shift to mainly positive ε Hf ( t ), supporting the mantle‐derived material addition and a Tethyan–Paleo‐Pacific double‐subduction system beneath Sundaland. However, the Hainan retains mostly negative ε Hf ( t ), consistent with continued Paleo‐Pacific subduction and older crustal components. These results clarify how the Tethyan and Paleo‐Pacific systems interacted in Southeast Asia.

Abstract Predicting the partial melting conditions that generate Li‐rich peraluminous melts is of major economic and societal importance. However, existing models disagree on the optimal conditions (e.g., pressure, temperature, protolith) and, consequently, on targets for exploration. A key source of divergence in model outcomes lies in the choices of partition coefficients used to describe lithium distribution between minerals and melt . Here, we use thermodynamic modeling to simulate isobaric stepwise partial melting of a global compilation of pelite compositions, at crustal pressures and considering variable water saturation and melt extraction thresholds, to calculate melt lithium enrichment predicted by four recently published sets. Our results quantify the conditions that maximize lithium enrichment. Depending on choices, the predicted optimal conditions range from high‐pressure, low‐temperature melting of wacke‐like compositions, to intermediate‐pressure, high‐temperature melting of both wacke‐ and shale‐like compositions, or in some cases show limited sensitivity to these parameters. Among these scenarios, the intermediate‐pressure, high‐temperature melting regimes (associated with biotite breakdown) are most consistent with existing geological and geochemical evidence from lithium‐rich granite and pegmatites. Such behavior is produced when lithium is treated as strongly compatible in biotite relative to other minerals, such as is thought to be the case in fluorinated biotite. Moving forward, pressure‐, temperature‐, and composition‐dependent lithium partitioning models—such as recently developed for biotite—will be crucial to accurately evaluate Li behavior in anatectic systems.

Abstract The Lunar Trailblazer (LTB) spacecraft launched on 27 February 2025, toward a planned low‐lunar orbit. Eleven hours into its mission, contact with Trailblazer was lost, and recovery efforts began. Estimating the orientation and angular velocity state of Trailblazer was central for recovery to determine whether and when the vehicle could be contacted again. This work documents a method to estimate Trailblazer's attitude state using only ground‐based optical telescopes. This data is cheap to collect and scales favorably with distance compared to radar data. We rely on photometric light curves, time histories of Trailblazer's observed brightness. The process of estimating Trailblazer's orientation and angular velocity from this data is known as light curve inversion. Light curve attitude inversion, in addition to inherent ambiguities caused by symmetries in the observed object's geometry and the geometry of the observation, is sensitive to the object's assumed surface materials. In this paper, we study the impact of surface material accuracy using two light curves of Trailblazer acquired by the 4.2‐m aperture Lowell Discovery Telescope in Arizona on 10 March 2025 and the 8.1‐m aperture Gemini South observatory in Chile on 9 April 2025. We produce two sets of solutions for each light curve: one using material properties derived from a solar radiation pressure model of the LTB, and a second using materials fit to laboratory reflectometry of Trailblazer's materials. We qualitatively compare solutions for both cases and perform a sensitivity analysis to quantify the dependence between the attitude solutions and material property errors.

Intensive conditions experienced by aquaculture animals increase their susceptibility to bacterial diseases, which promotes antibiotic use and contributes to the emergence of more resilient and virulent strains. Therefore, finding complementary effective alternatives to antibiotic therapy is a priority in animal health. Among them, one promising approach is the use of functional diets. Previous results of our group have demonstrated the benefits of phytobiotics (formulated as microencapsulated essential oils) in improving the resistance of shrimp against Vibrio parahaemolyticus infection. Thus, the aim of this proof-of-concept study was to evaluate the effect of a phytobiotic-enriched diet on survival of eels against Vibrio vulnificus pathovar piscis . This pathogen is responsible for warm-water vibriosis, a major concern in eel farming, causing significant economic losses and posing a threat for public health. First, phytobiotics were screened for in vitro bactericidal activity against multiple V. vulnificus strains, and the most effective candidates were incorporated into diets (0.9 g/kg feed). After four or five weeks of feeding, innate immune parameters were assessed, and the UV-1 supplemented diet contributed to the increase of plasma lysozyme activity in eels fed for five weeks. Second, two concentrations of the UV-1 (0.9 or 1.8 g/kg) were evaluated in terms of disease resistance after immersion challenge with the pathogen. After a controlled feeding trial, UV-1-enriched diets reduced mortality and significantly delayed disease progression, increasing survival by 1.9 days compared to the control group. These findings reinforce the potential of the UV-1 phytobiotic for developing functional diets that improve fish health (protection against bacterial diseases) and reduce antibiotic dependence in relevant cultured aquatic species.

Abstract This study investigates the petrogenesis of glassy agglutinates in a polished section of the Chang'e‐5 lunar regolith sample CE5C0800YJYX018GP through integrated petrographic, mineralogical, and geochemical analyses of four representative particles (18GP‐01 to 18GP‐04). The agglutinates contain diverse lithic clasts, including basaltic fragments, anorthositic fragments, and a barred olivine‐rich fragment, together with glass fragments. Mineral clasts are dominated by plagioclase, pyroxene, olivine, and ilmenite, with minor apatite, troilite, and silica phases. The glassy matrix formed primarily through impact melting of basaltic materials and shows compositions comparable to those of low‐Ti mare basalts from Oceanus Procellarum. In contrast, some glass domains exhibit strong enrichment in K (K 2 O up to 1.37 wt.%), P (P 2 O 5 up to 4.84 wt.%), and rare earth elements (ΣREE up to 3,196.1 ppm). These enriched domains display pronounced LREE enrichment, relatively flat HREEs, and negative Eu anomalies, similar to the KREEP‐rich lunar regolith from Oceanus Procellarum. Given the KREEP‐poor geochemical background of the Chang'e‐5 landing site, these features are most consistent with an exotic origin rather than in situ evolution of local basalts, and are best explained as material derived from the Procellarum KREEP Terrane and transported by large impact events. The micrometer‐scale, heterogeneous distribution of KREEP‐rich domains, together with agglutinated melt glass, and cristobalite, provides clear evidence for impact‐driven transport and mixing. These observations place new constraints on lunar material redistribution, the preservation of late‐stage magmatic residues, and the thermal evolution of the Moon.

Mineral–melt Li partition coefficients exert first-order control on predicted Li enrichment during crustal anatexis Geological observations favor Li enrichment during high-temperature biotite-dehydration melting rather than low-temperature melting scenarios

Reliable vessel identification is fundamental to maritime traffic safety and effective supervision. However, the Maritime Mobile Service Identity (MMSI) embedded in Automatic Identification System (AIS) messages can be deliberately altered, which compromises the integrity of situational awareness and poses risks to traffic management. To address this limitation, this study investigates vessel identity verification based on physical features inherent in AIS signals, shifting the focus from message-level identifiers to signal-level characteristics. A verification framework is developed by extracting stable physical features associated with onboard transmission hardware and the surrounding electromagnetic environment. To enhance discriminability, a feature fusion scheme is introduced to integrate complementary signal characteristics under varying channel conditions. In addition, a metric-constrained representation strategy is adopted to improve intra-class compactness and inter-class separability in the feature space. For decision-making, a hybrid criterion combining distance-based scoring with confidence control is employed, enabling both the reliable identification of known vessels and the effective rejection of previously unseen targets. The proposed approach is validated using AIS data collected in a port environment. The experimental results show that the method achieves an identification accuracy of 97.5% for known vessels while maintaining a rejection rate exceeding 90% for unknown vessels. The performance remains stable under complex and variable operating conditions. These findings demonstrate that AIS physical features provide a robust and reliable basis for vessel identity verification. The proposed framework offers a practical pathway to enhance the credibility of maritime traffic data and supports safer and more effective maritime governance.

Article title: MRW-YOLO: a lightweight and high-precision network for small object detection in remote sensing imagesAuthors: Yubin Qiu and Zufang LinJournal: INTERNATIONAL JOURNAL OF REMOTE SENSIN...