The Sn-W (-Mo) deposits of Myanmar are mostly located in the Western Granite Province that is well known for its world-class Sn-W (-Mo) deposits. Previous studies have constrained the age of the granitic intrusions of the province and the timing of mineralization for a few deposits, but most of the mineralization ages are not well established. In this study, new molybdenite Re-Os dating of two Sn-W-(Mo) regions, Padatgyaung and Dawei, together with their geological setting and mineral paragenesis are carried out to constrain the timing of ore formation and geodynamic setting. In the Padatgyaung region, two weighted average Re-Os model ages of 64.23 ± 0.29 Ma (MSWD = 0.49, 2σ) and of 60.54 ± 0.45 Ma (MSWD = 1.3, 2σ) from vein molybdenites are considerably younger than molybdenite from tin mineralized greisen which has a weighted Re-Os model age of 68.5 ± 2.7 Ma (MSWD = 0.14, 2σ). This demonstrates that the vein-type W-Mo mineralization formed after tin mineralized greisenization. Combining our new age data with previous geochronological data, the Re-Os model age of 63.09 ± 0.17 Ma from the Wagone quartz vein suggests that the Sn-W(-Mo) mineralization in the Dawei region took place at around 70–60 Ma (Late Cretaceous to Paleocene). This study indicates the presence of a significant and discrete granite-related Sn-W(-Mo) mineralization with an age of 75–60 Ma in the Western Granite Province, although the overall age range of Sn-W mineralization in the belt spans from 120 to around 40 Ma emplaced during normal subduction and roll-back of the Neo-Tethyan oceanic crust.

缅甸的Sn-W（-Mo）矿床大部分位于西部花岗岩省，该省以其世界一流的Sn-W（-Mo）矿床而闻名。先前的研究已经限制了该省花岗岩侵入的年龄和少数矿床的成矿时间，但大多数成矿年龄尚不明确。在这项研究中，对两个Sad-W-（Mo）区Padadgyaung和Dawei进行了新的辉钼矿Re-Os测年，以及它们的地质背景和矿物共生作用，以约束矿石形成和地球动力学背景的时间。在Padatgyaung地区，两个加权平均Re-Os模型年龄分别为64.23±0.29 Ma（MSWD = 0.49，2σ）和60.54±0.45 Ma（MSWD = 1.3，脉辉钼矿中的2σ）比锡矿化的格里森岩中的辉钼矿年轻得多，后者的加权Re-Os模型年龄为68.5±2.7 Ma（MSWD = 0.14，2σ）。这表明在锡矿化的格里森化后形成了脉型的W-Mo矿化。将我们的新年龄数据与以前的地质年代数据相结合，瓦格尼石英脉的Re-Os模型年龄为63.09±0.17 Ma，这表明大围地区的Sn-W（-Mo）矿化发生在70-60 Ma左右（晚白垩纪至古新世）。这项研究表明，西部花岗岩省存在与花岗岩相关的明显且离散的Sn-W（-Mo）矿化作用，年龄为75-60 Ma。