The Baoshan district in the southwestern Sanjiang Tethyan domain is an important part of the worldclass Southeast Asian tin (Sn) belt. However, the timing and controlling factors of Sn mineralization are poorly constrained. Here, we conducted laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of cassiterite and monazite, and cassiterite trace element analysis on the Shiganghe and Tiechang Sn deposits (Baoshan district) to unravel the temporal evolution of the regional Sn mineralization. The U–Pb dating of two cassiterite samples from Shiganghe yielded Tera-Wasserburg lower intercept ages of 75.5 ± 3.9 Ma and 75.9 ± 4.8 Ma. U-Pb dating on cassiterite and the cogenetic monazite from Tiechang yielded 32.8 ± 1.3 Ma and 32.2 ± 1.0 Ma, respectively. These ages confirm both Late Cretaceous and Oligocene Sn mineralization events in the Baoshan district. Geological characteristics, and age and geochemical data of cassiterite indicate that Shiganghe is a quartz-vein-type Sn deposit, genetically related to the Late Cretaceous granite that intruded the Ordovician Zhibenshan pluton. Tiechang resembles distal skarn Sn deposits related to the ~ 32 Ma magmatism along the Chongshan shear zone. Tin mineralization in the Tengchong-Baoshan district occurred mainly from the Late Cretaceous to Oligocene, corresponding to the Neo-Tethyan subduction and the subsequent India–Asia continental collision.

三江特提斯域西南部的宝山地区是世界级东南亚锡矿带的重要组成部分。然而，锡矿化的时间和控制因素却很少受到限制。在这里，我们对石岗河和铁场锡矿床（宝山区）进行了激光烧蚀-电感耦合等离子体质谱（LA-ICP-MS）U-Pb定年，并对锡石和独居石进行了锡石微量元素分析，以揭示其时间演化。区域锡矿化情况。对石岗河两块锡石样品进行 U-Pb 测年，得出 Tera-Wasserburg 较低截距年龄为 75.5±±3.9 Ma 和 75.9±±4.8 Ma。对锡石和铁场同生独居石进行 U-Pb 测年，结果分别为 32.8±1.3 Ma 和 32.2±1.0 Ma。这些年龄证实了保山区晚白垩世和渐新世锡矿化事件。地质特征、锡石年龄和地球化学数据表明，石岗河是一个石英脉型锡矿床，与侵入奥陶系知本山岩体的晚白垩世花岗岩有关。铁厂类似于与沿崇山剪切带 ~ 32 Ma 岩浆活动有关的远端夕卡岩锡矿床。腾冲-保山地区锡矿化主要发生在晚白垩世至渐新世，对应于新特提斯俯冲和随后的印度-亚洲大陆碰撞。