U-Pb zircon and cassiterite geochronology of Sn-W bearing granitoids at the Tagu mining area in the Myeik region, Southern Myanmar: Insight into ore genesis and metallogenic implication

The Tagu mining area, located in the Myeik region of Southern Myanmar, hosts significant Sn-W (tin-tungsten) mineralisation associated with granitoid intrusions. In the Tagu tin-tungsten deposit, mineralized quartz veins, nearly oriented in an east-west direction and either vertical or steeply dipping, are hosted by both Cretaceous to Eocene granite and Carboniferous to Early Permian metasedimentary rocks. Understanding the timing and evolution of these granitoids is crucial for unraveling the ore genesis and metallogenic implications of this economically important mineralized region. Zircon and cassiterite are ideal for geochronological analysis, as they preserve crystallization ages and offer key insights into a region's geological and metallogenic history. This study employed LA-ICP-MS U-Pb geochronology on zircon and cassiterite to determine the emplacement chronology of Sn-W-bearing granitoids, providing critical understanding of Sn-W ore deposit formation in southern Myanmar. LA ICP-MS zircon U-Pb age data of the host granitic rocks of the Tagu W-Sn deposit gave an age of 85.3 ± 1.5 Ma. Two cassiterite samples from the Tagu deposit yielded U-Pb ages of 88.0 ± 3.0 Ma and 75.6 ± 4.9 Ma and the ages are broadly similar to the age of host granite intrusion. Both zircon and cassiterite are well-zoned in the CL images which is suggesting their magmatic affinity. Geochemical characteristics and U-Pb ages of zircon and cassiterite indicate that the timing of the granitoid intrusions and the W-Sn mineralisation of the Tagu area is related to the post-collisional magmatism generated by the Neo-Tethyan Indian Ocean subduction and collision between the western Myanmar Terrane and the Sibumasu Terrane during the Cretaceous.