THE PALEOZOIC-EARLY MESOZOIC IGNEOUS ROCKS IN THE EAST SECTION OF XING'AN-MONGOLIAN OROGENIC BELT: Tectonic assemblage, division of tectonomagmatic stages and tectonic evolution

Based on the 1:50000 and 1:250000 regional geological survey in Jiayin, Yichun, Hegang, Jixi and Mudanjiang areas in recent years, with the concept of tectonic assemblage of igneous rocks, a preliminary plan on the division of Paleozoic tectonomagmatic stage is put forward, according to the zircon U-Pb age of the intrusive rocks. The igneous rocks that are related to oceanic crust subduction are divided into five stages, which are Caledonian Early Cambrian, Early-Middle Ordovician, Middle Silurian, Variscan Late Carboniferous and Late Permian. The igneous rocks that are related to continental collision is divided into two stages:Caledonian Early Cambrian and Variscan Middle Permian. The postorogenic A-type granite is recognized as two stages. On this basis, the Caledonian tectonomagmatic stage and Middle Variscan-Indosinian tectonomagmatic stage are set up. The point, which is different from the traditional view, will provide a new access to understand the tectonic evolution of this region.