Genetic relationship between W mineralization and granitic intrusion in Nanling Region, South China: Constraints from zircon and cassiterite u-pb age from new drill holes in Shangping deposit

Abstract

The Nanling metallogenic belt is known for the widely development of typical quartz vein type W deposit. These quartz veins that contain wolframite are frequently located in close proximity to granitic intrusions. The genetic relationship between tungsten mineralization and the associated granitic rocks is still a subject of controversy. The Shangping deposit stands out as a historically significant W deposit with a quartz vein type in the region of Nanling. However, the specific time that W mineralization occurred remains enigmatic. Granitic intrusions are absent from the mine and only granite porphyry dike is exposed, so the link between tungsten mineralization and magmatic activity remains unclear. Fortunately, in recent years, a concealed granite intrusive has been exposed in drill holes in the southeastern of the Shangping W deposit. To comprehensively address the connection between granitic magma activity and W mineralization, it is vital to make up a relative deficiency of geochronological information on granite and ore mineral. Here, in order to get the first direct age constraints on the origin of the Shangping W deposit, we use a combination of different techniques, incorporating the Hf isotope geochemistry of zirconium and cassiterite U-Pb assessment using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Based on these robust data, we tentatively evaluated the connection between W mineralization and granitic intrusion.For the granite porphyry, the majority of representative U-Pb zircon assays establish a ²⁰⁶Pb/²³⁸U age of 150.2 ± 0.5 Ma. An inferred emplacement age of ca. 151 Ma for the concealed granite in Kengweiwo is supported by a U-Pb isochron age from zircon. Combined with Hf isotopic characterization, it illuminates the mineralization potential of the Kengweiwo concealed granite. Cassiterite grains from hydrothermal quartz vein are subhedral to anhedral and have a lower intercept ²⁰⁶Pb/²³⁸U age of 153.9 ± 1.0 Ma. For the Shangping W deposit, all of these new geochronological dates provide well-constrained mineralization ages of 150–154 Ma. The dates of the concealed granite in the Kengweiwo area and the tungsten mineralization in the Shangping area are extremely concordant, indicating that they occurred roughly concurrently. The vein type tungsten mineralization in Shangping deposit may has a genetic link with crystallization of uncovered granite present at depth, which requires further investigation. These results emphasize the significance and potential of concealed granitic intrusion to host disseminated W mineralization in the deep part of Shangping deposit.