///A study of the Early Paleozoic volcanic rocks in Qimantag area reveals that they were formed in the Middle-Late Ordovician period. The volcanic rocks can be assigned to four volcanic rock belts, i.e., Gonglugou-luanshigou belt, Kuangou-Xiaolangyashan belt, Bayan Gol-Suhait belt and Naling Gol belt. U-Pb LA-ICPMS analyses of zircons in basalt and lithoidite yielded the data of (440.2±2.4) Ma and (450.3±1.2) Ma, respectively. The content of TiO2(1.1%) and K2O(0.14%) is low while that of Na2O(2.17%) is high for the rocks of the tholeiite combinations in the third belt. Although the content of TiO2(1.64%) is relatively high, the tholeiite combinations in the fourth belt are very similar to those in the third belt.