The major magmatic events in the Qimantag Mountain of Tibeatan Plateau since Paleozoic and its implications

In this study, four LA-ICP-MS zircon U-Pb ages (405.7±1.3Ma, 420.8±1.6Ma, 423.9±1.5Ma and 421.0±1.7Ma) were obtained in Kucaogou area, Qimantag Mountain, suggesting Late Silurian to Early Devonian. These zircons with high Th/U ratios are typical magmatic zircons, so these ages can present the granite and diorite petrogenetic ages. In combination with previously published results, the authors hold that two major magmatic events occurred respectively in 350~500Ma and 200~350Ma, corresponding to Early Paleozoic and Late Paleozoic-Early Mesozoic, respectively. The Early Paleozoic magma is the major mag-ma (> 60%), which is distributed in the north and west of the Qimantag Mountain. The major magma in the East Kunlun Mountains, which accounts for over 77% of the magma formed since Paleozoic, occurred during Late Paleozoic-Early Mesozoic. The magma formed during Late Paleozoic-Early Mesozoic and distributed in the southeast Qimantag Mountain is close to the East Kunlun Mountains, which means that this magmatic activity was probably influenced by the magmatic activity of East Kunlun Mountains. These results also imply that the activity of the Qimantag Ocean was stronger than that of the East Kunlun Ocean during Early Paleozoic, and the Qimantag Mountain and East Kunlun Mountains gradually formed a united orogenic belt since Late Paleozoic.