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China is rich in lithium resource, among which lithium ore in the Salt Lake has huge reserves, but the development and utilization technology has yet to be developed, and the main target of development is hard-rock lithium ore at present. Hard-rock lithium ore is mainly pegmatitic and concentrated in Xinjiang and Sichuan. The Mesozoic is the most important metallogenic period for pegmatite-type lithium deposits in China. A relatively stable tectonic environment after an orogeny is favored by the formation of pegmatite-type lithium deposits. After a decade of exploration practice and theoretical research, the types of lithium resource in China have shown a great variety. The brine-type lithium resource has expanded from surface brine to both shallow brine and deep brine, and the hard-rock lithium resources from single granitic pegmatite-type to altered granite-type, cryptoexplosion breccia tube-type and sedimentary-type. The metallogenic age has extended from the Meso-Cenozoic to the Paleozoic and other epochs. The metallogenic zones has increased from 12 to 16, and a number of new mineralized areas have been discovered in the Jiajika and Ke’eryin areas in western Sichuan and the Dahongliutan and Shaligou areas in Xinjiang . A new resource pattern of lithium is being formed. Moreover, Prospecting methods and exploration techniques have also developed from single surface prospecting and mapping to an integration of new techniques and methods, e.g., remote sensing to determine the prospective area, geological surveying to determine the type, geochemical prospecting to determine the mineral, geophysical prospecting to determine the location of drilling, drilling to determine the reserves, as well as biological prospecting, deep penetration of the deep exploration. In view of the rigid demand for lithium resources due to the rapid development of strategic emerging industries, it is suggested to strengthen a) the investigation, research, development and utilization of new types of lithium resources with lepidolite as the main industrial mineral and sedimentary-type lithium resources with Li-bearing clay as the main lithium resources; b) the research and prospecting of the Paleozoic and even Precambrian lithium deposits; c) the exploration of new lithium mineralization belts such as Altyn Tagh, Himalaya, Gangdise and western slope of Great Hinggan Mountains; d) the research on new mechanisms of dynamic management of lithium resources under market economy; e) the advanced research and resource reserve on lithium isotope as the raw material of controllable nuclear fusion, for leading the development of high-end mining industry.

Previous studies on the Ke'eryin pegmatite-type lithium ore field in the Songpan–Ganzi Orogenic Belt have explored the characteristics of the parent rock but have not precisely determined its magma source area. This uncertainty limits our understanding of the regularity of lithium ore formation in this region. In this study, to address the issue of the precise source area of the parent rock of lithium mineralization, a detailed analysis of the Li isotope composition of the ore-forming parent rock (Ke'eryin two-mica monzogranite) and its potential source rocks (Triassic Xikang Group metamorphic rocks) was conducted. The δ7Li values of the Ke'eryin two-mica monzogranite, Xikang Group metasandstone, and Xikang Group mica schist are −3.3–−0.7‰ (average: −1.43‰), +0.1–+6.9‰ (average: +3.83‰), and −9.1–0‰ (average: −5.00‰), respectively. The Li isotopic composition of the Ke'eryin two-mica monzogranite is notably different from the metasandstone and aligns more closely with the mica schist, suggesting that the mica schist is its primary source rock. The heavy Li isotopic composition of the two-mica monzogranite compared to the mica schist may have resulted from the separation of the peritectic garnet into the residual phase during the biotite dehydration melting process. Moreover, the low-temperature weathering of the source rocks may have been the main factor leading to the lighter lithium isotope composition of the Xikang Group mica schist compared to the metasandstone. Further analysis suggests that continental crust weathering and crustal folding and thickening play crucial roles in the enrichment of lithium during multi-cycle orogenies. [ABSTRACT FROM AUTHOR]

The saline soils in the Yellow River Delta are primarily affected by seawater intrusion resulting from the intersection of land and sea, which exhibit variations in salinity. The quality of these soils is also influenced by anthropogenic reclamation, including fertilization and irrigation. This study quantitatively evaluated the distinct soil properties and soil quality characteristics of the Yellow River Delta during different reclamation years (i.e., 0a, 1a, 5a, 10a, and 20a) using principal component analysis (PCA) and the Soil Quality Index (SQI). The findings indicated that the soil salt content (SSC) significantly decreased (p < 0.05) from 6.60 g/kg in the initial reclamation year (0a) to 1.63 g/kg in the 10th year (10a) and then slightly increased to 2.85 g/kg in the 20th year (20a). Consequently, the soil salinity level shifted from saline soil to slight salinity and then increased to medium salinity. Ammonium nitrogen (NH4+-N) notably increased by 8.31 mg/kg during the first five years of reclamation (0a to 5a) and gradually decreased by 2.56 mg/kg in the 20th year (20a). On the other hand, nitrate nitrogen (NO3−-N) experienced a significant decrease of 2–5 times after reclamation but continued to increase by 8.96 mg/kg with subsequent reclamation years. The available nitrogen (AN), available phosphorus (AP), and soil organic carbon (SOC) exhibited a significant increase of 24.87 mg/kg, 10.11 mg/kg, and 6.76 g/kg, respectively, with increasing reclamation years. However, available potassium (AK) gradually decreased after reclamation and then increased in the 20th year (20a). The values of SQI for different reclamation years were 0.307 for 0a, 0.339 for 1a, 0.320 for 5a, 0.318 for 10a, and 0.327 for 20a, indicating an increasing trend with increasing reclamation years. It was discovered that long-term reclamation significantly reduced soil salinity and improved soil quality, leading to the sustainable development of reclaimed saline soils in the Yellow River Delta. [ABSTRACT FROM AUTHOR]

Highlights: [·] Granite porphyry and Mo deposit dated at 165.49±0.59Ma and 160±1–162.7±1.1Ma. [·] Western and eastern Keshubei granites mark two discrete magmatic events at ca. 160Ma and 185–195Ma. [·] Ore-forming materials were derived from deep sources and partly from Yuanlingzhai porphyry. [ABSTRACT FROM AUTHOR]