Ningxia Water Conservancy

• Establishes the first precise mineralization age (230–240 Ma, Middle Triassic) for the Juyuan tungsten deposit using multi-method geochronology (in-situ zircon and wolframite/scheelite U-Pb, and muscovite Ar-Ar dating). • Identifies a coeval, highly fractionated I-type granite (242.0 ± 1.2 Ma) as the metallogenic source, formed in a post-orogenic intraplate extensional setting. • Extends the East Tianshan Triassic tungsten belt eastward, revealing significant quartz vein-type tungsten potential in the western Beishan orogenic belt. The Beishan Orogenic Belt, situated on the southern margin of the Central Asian Orogenic Belt, represents a significant endogenous metallic mineral resource base in northwestern China. Previous studies have indicated that tungsten mineralization in the Beishan Orogenic Belt primarily occurred from the Early Silurian to Middle Carboniferous. However, whether quartz vein-type tungsten mineralization developed during the Middle Triassic remains controversial. This study focuses on the newly discovered Juyuan tungsten deposit in the western segment of the Beishan Orogenic Belt. We investigated the geological characteristics, tectonic setting, and timing of magmatism and mineralization, establish a metallogenic model for the Juyuan deposit, and compare it with typical regional tungsten deposits to provide guidance for future mineral exploration through systematic fieldwork, geochemical analyses, and isotopic geochronology, and show that the zircon U-Pb age of the monzogranite in the mining area is 242.0 ± 1.2 Ma. The granite exhibits high SiO 2 , high alkalinity, high Al 2 O 3 , and low CaO characteristics, identifying it as a highly fractionated I-type granite formed in a post-orogenic intraplate extensional setting. The 40 Ar- 39 Ar plateau age of muscovite from the ore-bearing quartz veins is 239.97 ± 0.98 Ma, while the insitu U-Pb ages of wolframite and scheelite are 232 ± 14 Ma and 236 ± 24 Ma, respectively, collectively constraining the mineralization age to between 230 and 240 Ma. This study demonstrates that the Juyuan tungsten deposit is a quartz vein-type tungsten deposit closely related to magmatic-hydrothermal processes. The East Tianshan Triassic tungsten metallogenic belt can be extended eastward into the Beishan Orogenic Belt, indicating significant potential for exploring quartz vein-type tungsten deposits in an intraplate extensional setting in its western segment.

Understanding the interactions between human activities and ecosystems is crucial to enhancing human well-being and adaptive governance. This study employs the human footprint index (HFI) and the ecosystem quality index (EQI), along with multivariate statistical methods, to analyze human-nature relationships and their driving mechanisms in the Yangtze river delta urban agglomeration (YRDUA). The results show a steady increase in HFI and a decline in EQI from 2000 to 2020 in the YRDUA. The ratio of coordinated to conflicting areas has remained stable at approximately 3:5. Over 95% of the coupling coordination degree (CCD) were classified as primarily or moderately coordinated. Vegetation cover and human activity intensity were the main positive drivers of CCD in coordinated and conflicting regions, respectively, while terrain and climate were the dominant negative drivers. These findings deepen our understanding of human-nature interactions in urbanized areas, offering valuable insights for targeted ecosystem restoration.

To investigate the deformation characteristics of coarse-grained sulfate–saline soil subgrades to the thermal responses of pavement structures in cold arid environments with significant diurnal temperature variations, this study focuses on a highway located in the Tarim Basin in Northwest China. Three test sections (K-I, K-II, and K-III) were constructed, each featuring distinct configurations of pavement base layers. The designs of these sections depend on the characteristics of the pore structure and cement content. Multifactor monitoring of moisture, heat, salt, and mechanics was conducted to evaluate the deformation behavior of the subgrade under varying thermal conditions. Section K-I with the insulated low-cement-dosage skeleton-dense gradation (insulated LC-SDG) base exhibits the smallest daily temperature amplitude of 3.1°C and low thermal sensitivity. Section K-III with the pavement base of high-cement-dosage suspension-dense gradation (HC-SusDG) displays the highest thermal sensitivity, recording an annual temperature amplitude that exceeds that of Section K-II (LC-SDG) and Section K-I by 2.5%–4.0%. This intensifies the phase transition in high-sulfate subgrade soils of Section K-III, where the latent heat released during crystallization slows the temperature decline at the subgrade surface during cooling periods. In Section K-III, pronounced dissolution-crystallization cycles of moisture and salt, coupled with steep thermal gradients, result in excessive moisture-salt accumulation beneath the upper impermeable layer, which is 6.9–15.4 times higher than that in Sections K-II and K-I. Consequently, the subgrade surface experiences a peak soil pressure of 229.6 kPa, cyclic pressure amplitudes of 3.7 kPa, and salt-induced pressure increments of 3.4 kPa in Section K-III. These stresses promote the accumulation of tensile strain, and during the optimal salt heaving period (December–February), the peak reaches only 212.8 × 10−6 at the subbase of Section K-I. The thermal regulation and cement content-optimization of pavement structures are critical for mitigating the deformation of sulfate–saline soil subgrades in cold arid regions. These findings provide theoretical guidance for enhancing regional pavement design and construction techniques.

The traditional “trial and error” microstructural control method, with high cost and low efficiency, has become a key issue restricting the development of ultra-high strength and toughness titanium alloys. This study adopts the molybdenum equivalent (Mo[eq]) method to rapidly design Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys (x=5–9). The as-cast alloys with different Mo[eq] exhibit a single peak of the β phase in XRD. The β grains of 5Mo alloy (the lowest Mo[eq]) exhibit elongated columnar grain characteristics. As the Mo[eq] increases, the β grains transition towards a more equiaxed form, resulting in a decrease in aspect ratio and a reduction in grain size. As the Mo[eq] increases, the α phase content gradually decreases and the α phase is almost unobservable in 9Mo alloy (the highest Mo[eq]). The α phase in 5Mo alloy exhibits short rod-shaped shapes with an average length of about 2.4 µm, while the α phase in 6Mo alloy shows an equiaxed and short rod shapes with the smallest size. The strength, plasticity, and toughness are the lowest in 5Mo alloy, with values of 867 MPa, 7.3%, and 56 MPa·m1/2, respectively. However, it reaches its maximum in 6Mo alloy, where the strength, plasticity, and toughness increase to 984 MPa, 12.8%, and 74 MPa·m1/2, respectively. The mechanical properties of Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys are affected mainly by solid-solution strengthening of Mo element, refinement of β grain, and changes in α/β phase content. This study lays a certain theoretical foundation for the theoretical research and composition development of new ultra-high strength and toughness titanium alloys.