A Comparative Study on Isotopic Geochronology and Tectonic-magmatic Hydrothermal Events of Igneous Rock in Qinghai Province

Based on the age results the project team have gained in recent years, a comparative study is conducted on igneous rocks in terms of distribution and geological evolution of 1346 isotopic ages collected, and conclusions are drawn as follows (1) The peak value of Qingbaikou series thermal event indicates that Proto-Tethys evolution began in the end of Mesoproterozoic Era in Northeastern Margin of the Tibetan Plateau; (2) Magmatism presents a hysteretic nature compared with tectonic movement in the evolution of Paleo-Tethys evolution, which is rather common in the whole Northeastern Margin of the Tibetan Plateau; (3) The Variscan-Indosinian tectonic evolution cycle is not continuous, specifically, interruptions may take place during the late Permian to Early Triassic; (4) All the phenomenon show that East Kunlun Devonian is in a continuous strong extension period, with a large number of elastic basic rock and A-type granite occurrence, which began from 406Ma and ended no early than 380Ma.