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The Tibetan Plateau is a product of the continental collision between the Indian and Asian plates along the Indus-Yarlung suture zone that started in the early Cenozoic. This collision initially produced stress at the collisional boundary and later propagated with time on both the Indian plate and Asian plate. Many studies have reported tectonic deformation in the Himalayas representing the immediate response of continental collision on the Indian side near the collisional boundary. However, there have been only few studies on the early Cenozoic shortening structures in the Lhasa block that forms the southernmost part of the Asian plate. In this study, we performed Ar/Ar geochronology of syntectonic muscovite from the Sinongduo thrust system in the central Lhasa block. The results show that the Sinongduo thrust system was active in the Early Eocene. We interpret the Sinongduo thrust system as an immediate response to the India-Asia collision in the Lhasa block. This study reconciles the early Cenozoic India-Asia collision with the lack of tectonic response in the Lhasa block. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the effects of exhaust direction on exhaust plume and helicopter infrared radiation in hover and cruise status. Design/methodology/approach: Four exhaust modes are concerned, and the external flow field and fuselage temperature field are calculated by numerical simulation. The infrared radiation intensity distributions of the four models in hovering and cruising states are computed by the ray-tracing method. Findings: Under the hover status, the exhaust plume is deflected to flow downward after it exhausts from the nozzle exit, upon the impact of the main-rotor downwash. Besides, the exhaust plume shows a "swirling" movement following the main-rotor rotational direction. The forward-flight flow helps prevent the hot exhaust plume from a collision with the helicopter fuselage generally for the cruise status. In general, the oblique-upward exhaust mode provides moderate infrared radiation intensities in all of the viewing directions, either under the hover or the cruise status. Compared with the hover status, the infrared radiation intensity distribution alters somewhat in cruise. Originality/value: Illustrating the influences of exhaust direction on plume flow and helicopter infrared radiation and the differences of helicopter infrared radiation under hover and cruise statuses are identified. Finally, an appropriate exhaust mode is proposed to provide a better IR signature distribution. [ABSTRACT FROM AUTHOR]

Continental crust has long been considered too buoyant to be subducted beneath another continent, although geophysical evidence in collision zones predict continental crust subduction. This is particularly significant where upper continental crust is detached allowing the lower continental crust to subduct, albeit the mechanism of such subduction and recycling of the upper continental crust remain poorly understood. Here, we investigate Paleocene S-type magmatic and volcanic rocks from the Linzizong volcanic succession in the southern Lhasa block of Tibet. These rocks exhibit highly enriched 87Sr/86Sr, 207Pb/206Pb and 208Pb/206Pb together with depleted 143Nd/144Nd isotope ratios. The geochemical and isotopic features of these rocks are consistent with those of modern upper continental crust. We conclude that these Paleocene S-type volcanic and magmatic rocks originated from the melting of the upper continental crust from microcontinent subduction during the late stage of India–Asia convergence. [ABSTRACT FROM AUTHOR]

The Sinongduo mining region includes two types of mineralizations: the epithermal and the carbonate‐hosted Pb‐Zn‐Ag deposits. Despite being studied for many years, the ore formation process and genesis of the carbonate‐hosted Pb‐Zn‐Ag deposits remain poorly understood. The Pb‐Zn‐Ag ore bodies occur as veins and are hosted by limestone and dolostone of the Permian Xiala Formation. Three sulfide mineralization substages have been identified at the Sinongduo carbonate‐hosted deposit. Indium coupled with Cu, Co and Sn was incorporated into sphalerite as substitutions: 2Zn2+ ↔ Cu+ + In3+, (3n/2 + 1)Zn2+ ↔ Co2+ + nIn3+ or (2n + 1)Zn2+ ↔ Co2+ + n(Cu+ + In3+) (n > 1) and 4Zn2+ ↔ Sn2+ + 2In3+. Sphalerite and pyrite in the mineralization stage display δ34S values in a narrow range of +5.7‰ to +11.3‰, which are similar to those of Palaeocene igneous rocks, indicative of a magmatic source of sulfur. We present systematic carbon‐hydrogen‐oxygen isotope results that further support a magmatic source for the ore‐forming fluids that were influenced by meteoric water. Furthermore, the Pb isotope compositions of sulfide minerals in the Sinongduo carbonate‐hosted deposit overlap with the values of coeval Linzizong volcanic rocks and are similar to those of Indian Ocean sediments, indicating upper crustal sources of metals. We conclude that the Sinongduo carbonate‐hosted Pb‐Zn‐Ag deposit is a medium‐ to low‐temperature magmatic‐hydrothermal deposit related to Linzizong magmatism. [ABSTRACT FROM AUTHOR]

• The first framework for estimating plastic litter from aquaculture was developed. • The framework was applied to a plastic load survey of oyster farming in the Maowei Sea. • The plastic load from aquaculture approximates the plastic input of a river. • This source-based approach to plastic litter evaluation is suitable for management. • This framework can be extended to other aquaculture patterns. Aquaculture provides livelihoods for hundreds of millions of people, but it also forms a significant source of plastic litter that poses a serious hazard to aquatic ecosystems. How to assess and subsequently manage plastic loads from aquaculture is a pending and pressing issue for aquaculture sustainability, and an important concern for water environment monitoring and management. In this study, we developed the first framework for estimating plastic litter from aquaculture by combining data from satellite remote sensing, drones, questionnaires, and in situ measurements. By acquiring multidimensional (human and nature) and multiscale (centimeter to basin scale) data, this framework helped us understand the aquaculture farming patterns and its spatial and temporal evolution, and thus estimate the plastic load it generates and suggest effective management approaches. Applying this framework, we assessed the marine plastic load from oyster floating raft farming in the Maowei Sea, a typical mariculture bay in China, with an increasing farming area. Approximately 3840 tons of plastic waste is expected to be discharged into the sea in the next four years (the average service life of a floating raft) without improvements in aquaculture waste management. Strengthening governance, timely plastic removal, innovative replacement, and transforming farmers' behavior patterns are recommended as the subsequent measures for plastic management. This framework can be extended to other regions and other aquaculture patterns, and is applicable to local, regional, and global aquaculture plastic litter assessments. It is a source-based method for evaluating plastic pollution that is more conducive to subsequent plastic management than traditional post-contamination environmental monitoring. In the context of the global expansion of mariculture and the global commitment to action to combat plastic pollution, this approach could play a critical role in the investigation and management of plastic waste in aquatic environments. [Display omitted] [ABSTRACT FROM AUTHOR]

A numerical investigation is performed in the current study to illustrate the influences of exhaust angle of the integrated infrared suppressor on plume flow and helicopter infrared radiation, under the hover and cruise statuses. Three exhaust models are concerned, including the exhaust direction at 60°, 45°, and 18° angles to the horizontal plane. The results show that the heating effect of the exhaust plume on the fuselage is modified with the decrease of the exhaust angle. However, the decrease in exhaust angle will reduce the pumping coefficient of the mixing duct to some extent, resulting in an increase of exhaust temperature. For the model with an exhaust angle of 18°, three sets of comparative tests were designed. The results show that when there is no airflow outlet at the bottom of the fuselage, the surface temperature of the fuselage will increase significantly, and the position of the airflow outlet at the bottom of the fuselage also has a certain influence on the temperature field of the fuselage. On the horizontal detection plane, the infrared radiation intensity of the model with an exhaust angle of 60° and 45° is significantly lower than that with an exhaust angle of 18°. In the vertical detection plane, especially in the direction below the fuselage, the infrared radiation intensity of the model with an exhaust angle of 18° is the smallest. When compared to the hover status, the cruise status reduces the infrared radiation intensity somewhat. [ABSTRACT FROM AUTHOR]

We report zircon U Pb age and Hf isotope and whole-rock major and trace element and Sr Nd isotope data for magnesian andesites from the Kongnongla area, central Tibet. These Kongnongla magnesian andesites are directly in contact with high-Nb basalts and are part of the Baila–Lanong ophiolitic mélanges. Zircon U Pb dating shows that the magnesian andesites crystallized at ca. 158 Ma. The samples are characterized by moderate SiO 2 (59.3–61.7 wt%), high MgO (3.74–4.69 wt%), Fe 2 OT 3 (4.95–5.30 wt%), Ba (570–1320 ppm), and Th (6.5–7.0 ppm) contents, and low (87Sr/86Sr) i (0.704491–0.704857), and Sr/Y (17.5–24.0) ratios. The samples also exhibit enrichments of compatible elements, such as Cr (110–150 ppm) and Ni (24.7–36.5 ppm), and display fractionated rare earth element (REE) patterns with light REE enrichment relative to heavy REEs. Negative zircon ε Hf (t) values (−10.8 to −15.7) and whole-rock ε Nd (t) values (−3.85 to −6.12) of the Kongnongla magnesian andesites are similar to those of DaruTso magnesian andesites, Hohxili high magnesian andesites, and sediments of the Mugagangri Group. We propose that the Kongnongla magnesian andesites were formed by the interaction between slab fluids, subducting sediments, and overlying mantle under high-temperature–low-pressure conditions. Based on previously published data and the regional geology, we also suggest that these magnesian andesites were generated in a back-arc setting caused by the southward subduction of the Bangong–Nujiang oceanic lithosphere during the Late Jurassic. • The Dongqiao area is a microcontinent preserved in the Bangong–Nujiang suture. • The Kongnongla magnesian andesites formed in a back-arc setting. • Southward subduction of the Bangong-Nujiang Ocean triggered back-arc spreading. [ABSTRACT FROM AUTHOR]

The Jiama deposit, a significant porphyry‐skarn‐type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet, China, exemplifies a typical porphyry metallogenic system. However, the mineral chemistry of its accessory minerals remains under‐examined, posing challenges for resource assessment and ore prospecting. Utilizing electron microprobe analysis and LA‐ICP‐MS analysis, this study investigated the geochemical characteristics of apatite in ore‐bearing granite and monzogranite porphyries, as well as granodiorite, quartz diorite, and dark diorite porphyries in the deposit. It also delved into the diagenetic and metallogenic information from these geochemical signatures. Key findings include: (1) The SiO2 content, rare earth element (REE) contents, and REE partition coefficients of apatite indicate that the dark diorite porphyry possibly does not share a cogenetic magma source with the other four types of porphyries; (2) the volatile F and Cl contents in apatite, along with their ratio, indicate the Jiama deposit, formed in a collisional setting, demonstrates lower Cl/F ratios in apatite than the same type of deposits formed in a subduction environment; (3) compared to non‐ore‐bearing rock bodies in other deposits formed in a collisional setting, apatite in the Jiama deposit exhibits lower Ce and Ga contents. This might indicate that rock bodies in the Jiama deposit have higher oxygen fugacity. Nevertheless, the marginal variation in oxygen fugacity between ore‐bearing and non‐ore‐bearing rock bodies within the deposit suggests oxygen fugacity may not serve as the decisive factor in the ore‐hosting potential of rock bodies in the Jiama deposit. [ABSTRACT FROM AUTHOR]

Two typical topology shapes of the microstrip meander line (MML) including round U-shaped and V-shaped slow-wave structure (SWS) for ${D}$ -band traveling wave tubes (TWTs) are comparatively investigated, fabricated, and tested in this article. As a critical factor applied in millimeter-wave frequency, the high-frequency losses of the MML SWS are emphatically discussed. The two types of golden SWSs are both fabricated with the thin-film circuit technology on quartz substrates. After the surface roughness test and the cavity fabrication, the SWS samples are assembled and tested. According to the experimental test results, the ${S}_{11}$ parameters of the U-shaped and V-shaped transmission models are below −13.5 dB versus −15 dB, and the “cold” ${S}_{21}$ parameters are over −6.4 dB versus −4.9 dB, which are approached to the simulation results with the consideration of the silver conductive paste (SCP). At 140 GHz, the tested transmission losses for the U-shaped SWS and V-shaped SWS are about 0.35 and 0.29 dB/mm, respectively. Although particle-in-cell (PIC) simulations for the two SWSs both predict more than 100-W output power, the V-shaped MML TWT shows better bandwidth and loss performances than the U-shaped MML TWT. [ABSTRACT FROM AUTHOR]

The granite blocks are widely distributed on granite residual soil slopes, particularly in the circumstances of humid granitic terrain. These blocks may be partially buried in the soil slope with their long axis upright, which results in complex toppling mechanisms. The objective of this study is to investigate the mechanical stability of the blocks against toppling failure, considering extremely heavy rainfall. Based on the analysis of limit equilibrium, an analytical formulation taking the influence of the block overhang length and the slope inclination into account is proposed to calculate the factor of safety (FOS) of the blocks partially buried in the soil slope. The results of the model experiments verified the performance of this formulation by showing a consistent behavior regarding the stability of the block with the formulation. The FOS obtained from this analytical formulation first shows a trend of increase and then a decrease according to the overhang length of the blocks. Furthermore, the critical overhang length and the critical slope inclination were found related to the toppling failure of potential blocks. The analytical formula obtained in this study can be used to determine the factor of safety against toppling of the single blocks on granite residual soil slopes, which provide a quantitative method for risk evaluation of toppling disaster in granitic regions. • Single blocks on granite residual soil slopes are partially buried with long axis upright. • A calculating formulation for the factor of safety of single blocks is newly present. • Overhang length of blocks and slope inclination significantly affect the toppling instability. [ABSTRACT FROM AUTHOR]