Geologic characteristics, metallogenic age and prospecting potential in the Altyn Shaliangxi lithium polymetallic deposit, Ruoqiang County, Xinjiang

This paper is the results of mineral exploration engineering.

Objective Lithium, as a critical strategic mineral resource, plays an increasingly essential role in the development of the new energy sector. A newly discovered lithium polymetallic deposit in the Shaliangxi area of Ruoqiang County, Xinjiang, has attracted significant attention in recent years. This study aims to elucidate the geological setting, mineralization age, and genetic mechanisms of the deposit, and to assess its exploration potential, thereby providing a theoretical basis for future rare-metal prospecting.

Methods Based on systematic field geological surveys, this research integrates petrographic analysis, geochemical characterization, and U–Pb isotopic dating of multiple zircon and ore mineral types. Laser ablation-inductively coupled plasma mass spectrometry (LA–ICP–MS) was employed to obtain high-precision U–Pb ages for zircons from biotite monzogranite, mineralized pegmatite, and for columbite–tantalite minerals.

Results The study area lies in the foreland zone at the junction of the Altyn Tagh orogenic belt and the southern margin of the Tarim Basin, characterized by intense tectonic activity. Exposed lithologies are dominated by the Changcheng and Jixian systems, composed mainly of biotite quartz schist, siliceous rock, and marble. The stratigraphic sequence exhibits structural inversion and overall southward dip due to regional thrust faulting and nappe deformation. Intrusive granitic bodies are developed in the southern part of the area. Three spodumene-bearing pegmatite dike zones have been identified, delineating 25 lithium−bearing ore bodies. The longest individual ore body extends up to 776 m with a maximum thickness of 7.7 m. Li₂O grades range from 0.80% to 1.84%, accompanied by (Nb,Ta)₂O₅ concentrations of 0.032%~0.091%. The estimated Li₂O resource scale reaches or exceeds the medium-sized deposit threshold. Zircon U-Pb dating indicates an age of (440.9±4.6) Ma for the biotite monzogranite (Early Silurian), while zircons in the pegmatites are predominantly inherited grains older than 736 Ma. The columbite-tantalite U–Pb age constrains the mineralization to (228.8±5.8) Ma (Late Triassic).

Conclusions The Shaliangxi lithium polymetallic deposit is classified as a typical granitic pegmatite-type lithium deposit. Its mineralization age (Late Triassic) is significantly younger than the emplacement age of the Caledonian granites in the region, indicating no direct genetic relationship between the two. The formation of the deposit is likely linked to deep crustal remelting events triggered by tectonic regime transformation during the Indosinian orogeny. These findings define a new temporal window for rare metal mineralization within the Altyn metallogenic belt and highlight the region's considerable exploration potential.