Objective Rare metals are an important subset of critical strategic metals, and their mineralization is closely related to the granite–pegmatite system. As direct products of mineralization, the crystallization behavior and evolutionary patterns of rare-metal minerals provide an essential basis for understanding metallogenic mechanisms, assessing resource potential, and predicting ore-forming districts. Methods A systematic analysis of rare-metal minerals in different geological and metallogenic settings has been carried out. Results This study identifies (hydro)oxides, silicates, and phosphates as the main types of rare-metal ore minerals and systematically analyzes their mineralogical characteristics. At the global scale, it investigates the evolutionary features of these minerals during key geological periods, revealing the relationship between rare-metal mineralization and supercontinent assembly–breakup cycles. Based on differences in element electronegativity, it establishes the relationship between the chemical behavior of rare elements and their mineralization potential, elucidating the fundamental processes of rare-metal enrichment and mineralization. At the orebody scale, it systematically analyzes the crystallization sequence of lithium minerals and develops a generalized evolutionary framework for lithium mineralization in rare-metal pegmatites. Furthermore, from the perspective of compositional evolution in Nb–Ta and Zr–Hf minerals, it develops a multi-dimensional tracing system for rare-metal mineralization. Conclusions This study establishes a comprehensive mineral system for rare-metal mineralization and develops a mineral-centered mineralization processes, thereby advancing our understanding of the evolutionary patterns of rare-metal mineralization. Significance This work will promote the establishment of a spatial prospecting methodology based on mineralogical responses and offer theoretical support for rare-metal resource exploration.
Objective The Telaaobao uranium deposit is the first super-large uranium deposit hosted in the Lower Cretaceous strata in the northern Ordos Basin. Its sedimentary setting is markedly different from that of the numerous uranium deposits previously studied in the Middle Jurassic Zhiluo Formation. The uranium-bearing sandstone reservoirs in this deposit are notably deficient in traditional reducing agents, such as carbonaceous debris and pyrite. This limited understanding of reducing media has significantly hindered the refinement of uranium metallogenic models and the advancement of successful exploration. This study aims to identify the types and genetic characteristics of reducing media in the Telaaobao uranium deposit and elucidate their roles in uranium mineralization. Methods Optical microscopy, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and electron probe microanalysis (EPMA) were employed, together with fluorescence analysis, sulfur isotope analysis, and acidolysis hydrocarbon analysis to characterize the reducing media and investigate their origins and roles in uranium mineralization. The findings were interpreted within the framework of the metallogenic model of the Telaaobao uranium deposit. Results Four types of reducing media were identified: carbonaceous debris, pyrite, hydrocarbon-bearing fluids, and chlorite. Hydrocarbon-bearing fluids were identified as the predominant reducing medium. The carbonaceous debris was mainly allochthonous and derived from older strata. Sulfur in pyrite primarily originated from bacteriogenic sulfides and organic sulfides. The hydrocarbon-bearing fluids were sourced from deep coal-, oil-, and gas-bearing strata and migrated into the deposit via faults in its vicinity. Chlorite can be subdivided into alteration products of mica and feldspar and authigenic chlorite. Conclusions Based on the Telao Bao metallogenic model, the types and roles of reducing media during different mineralization stages were discussed: (1) During the sedimentary-diagenetic stage in the early Early Cretaceous, the main reducing media were carbonaceous debris and metal sulfides such as pyrite; (2) In the late Early Cretaceous large-scale reduction stage, the principal reducing medium was deep-sourced hydrocarbon-bearing fluids; (3) From the Late Cretaceous to the Oligocene, during the secondary oxidation–mineralization stage, chlorite further enhanced the reducing capacity of the sandstone reservoirs, ultimately leading to termination of redox-driven mineralization. Significance These findings clarify the types, origins, and stage-specific roles of reducing media in the Telaaobao uranium deposit, highlighting the importance of deep-sourced hydrocarbon-bearing fluids in uranium mineralization. The results provide a basis for refining the metallogenic model of the deposit and may inform uranium exploration in comparable geological settings.
Objective Thrust nappe structures are widely developed in the Qiangtang Basin. Clarifying the episodes and structural styles of this tectonic movement is of great significance for oil and gas exploration in the Qiangtang Basin. Methods Detailed field observations combined with integrated interpretation of 2D seismic data reveal two episodes of long-distance southward thrusting in the Shuanghu area of the central Tibetan Plateau, one in the Late Cretaceous and the other in the Paleogene. Results Late Cretaceous southward thrusting formed a huge nappe of the Bilogco–Andarco Paleo-petroliferous System (BAPS) overlying the Upper Cretaceous Abushan Formation (Fm), and rooted in the Dirangbico–South Yaqu Thrust (DST). The minimal displacement of the BAPS–DST thrust system is 116 km, corresponding to more than 54% crustal shortening in the Late Cretaceous. The Paleogene southward thrusting occurring north of the DST formed the Dawoco–Tuco Thrust (DTT) in the Northern Qiangtang Depression. The minimal displacement of the DTT is 38 km, corresponding to more than 53% crustal shortening. Conclusions Both the DST–BAPS and the DTT are thin-skinned thrusts, and thick gypsum layers in the Lower–Middle Jurassic formations act as favorable detachment layers for the long-displacement thrust. The foreland basins and molasse formations of the Abushan and Kangtuo Fms. formed along the BAPS-–DST and DTT thrust fronts in the Late Cretaceous and Paleogene, respectively. Significance Long-displacement thrusting in the Shuanghu area is key to the accumulation and preservation of oil and gas in the central Qiangtang Basin.
Objective Tungsten and tin are strategic critical metals in China. The Northern Jiangxi–Southern Anhui metallogenic belt in the eastern Jiangnan Orogen is a newly recognized world-class tungsten-rich province. This study aims to supplement the traditional understanding that tungsten mineralization is solely controlled by S-type granites, clarify the differences in W-Sn mineralization related to S-, I-, and A-type granites, reveal geodynamic metallogenic mechanisms, establish regional metallogenic models, and support deep mineral exploration. Methods Based on field geological investigations, petrographic observations, U–Pb dating of zircon and other hydrothermal minerals, molybdenite Re–Os geochronology, Sr–Nd–Hf isotopes, in-situ trace-element analysis of minerals, and fluid-inclusion data, typical deposits including Zhuxi, Dahutang, Xianglushan, Yangchuling, Dongyuan and Xiwukou were systematically compared. Metallogenic processes were analyzed under the classification of S-, I- and A-type granites, and the migration-enrichment of ore-forming materials was summarized. Results (1) The total W resources in this belt exceed those in the Nanling metallogenic belt, with major Yanshanian metallogenic ages of 150–130 Ma. (2) S-type granites host the giant Zhuxi and Dahutang W-Cu polymetal deposits, characterized by strongly peraluminous, reduced magmas and skarn-superimposed mineralization. (3) I-type granites host medium-to-large W-Mo polymetal deposits, such as Xianglushan, Yangchuling, and Dongyuan, which formed under medium-to-high temperature conditions in weakly-peraluminous systems with porphyry-skarn mineralization; calcium for scheelite formation derives either from carbonate wall rocks or silicate-mineral (e.g, plagioclase) alteration within plutons. (4) The A-type-granite-related Xiwukou Sn-W-Rb deposit records highly fractionated, F-rich magmatism with the enrichment of Sn, Rb, and other rare metals. (5) A three-stage enrichment model is established: basement pre-enrichment, Mesozoic crust-mantle interaction, and magmatic fluid exsolution and unloading. Regional mineralization is likely driven by Paleo-Pacific slab rollback and lithospheric extension. (6) Four categories of deep prospecting targets, e.g. fault intersections and concealed pluton domes, are proposed. Conclusions The W-Sn mineralization in the Jiangnan Orogen is not restricted to S-type granites; S-, I- and A-type granites constitute differentiated metallogenic systems. The W-Sn-enriched meta-sedimentary rock basement of the Shuangqiaoshan Group provides primary ore-forming materials, while crust-mantle interaction supplies heat and partial components; magma differentiation and fluid evolution dominate metal precipitation. Significance This work improves the regional understanding of W-Sn metallogenesis and provides theoretical support for the deep exploration of strategic critical minerals, not only in Northern Jiangxi-Southern Anhui provinces but also in other areas with similar geological conditions.
