Work

The metallogenic age and geodynamic setting of tin deposits in East Junggar, NW China: Constraints from cassiterite and zircon U-Pb geochronology and geochemistry

Year: 2025

Type: article

Abstract: • Tin mineralization in East Junggar occurs as porphyry-type, greisen-type, and quartz vein-type deposits. • The mineralization event is precisely dated at ∼305 Ma by cassiterite U-Pb geochronology. • East Junggar experienced A-type granite emplacement at ∼310 Ma in an extensional regime. • The granites were predominantly derived from partial melting of juvenile crustal material. The East Junggar tin metallogenic belt in Northwest China hosts a variety of tin deposits, including Kamusite, Sareshike, Ganliangzi, and Beilekuduke deposits. Zircon U-Pb ages were obtained for the Kamusite (KMST) biotite granite (309.4 ± 1.3 Ma) hosting greisen-type tin mineralization and for the Sareshike (SRSK) alkaline granite (310.7 ± 1.0 Ma) associated with quartz vein-type mineralization, respectively. Cassiterite U-Pb dating of the Sareshike deposit yielded an age of 305.4 ± 1.4 Ma, indicating a slightly later mineralization event compared to the granite crystallization. The granites related to the tin mineralization were characterized by high silica (77.11–85.90 wt%) and alkali (K 2 O + Na 2 O = 4.04–9.23 wt%) contents but low CaO (0.23 wt% on average) and MgO (0.05 wt% on average) contents. The rare earth element (REE) concentrations range from 68.54 × 10 −6 to 231.15 × 10 −6 , with obviously negative δEu values (average of 0.02) in the chondrite-normalized REE patterns. The HFSE enrichment and high FeO t /MgO and (Na 2 O + K 2 O)/CaO ratios, coupled with remarkably low Ba, Sr, and Eu concentrations, collectively indicate an A-type affinity for the granites. Additionally, positive zircon ε Hf(t) values (with a mean of +13.7) indicated that the granite magmas were likely derived from partial melting of juvenile crustal material. Titanium-in-zircon thermometry reveals that the zircon crystallization temperatures decreased from KMST to SRSK granites during mineralization. The KMST granite was inferred to be more hydrous than the SRSK granite with significantly higher Eu/Eu* ratios. Thus, the magma crystallization temperature, oxygen fugacity, and water content probably jointly controlled the diverse mineralization styles of the tin deposits in East Junggar. Additionally, integrating lithological, petrogeochemical, and comparative analyses, the magmatism which produced the A-type granites occurred in an extensional tectonic setting during the late Carboniferous. The genetic model for the Kamusite and Sareshike tin deposits in East Junggar proposed in this study, provides insights into tin prospecting in the region.

Source: Ore Geology Reviews

DOI: 10.1016/j.oregeorev.2025.106997