Abstract:The existence of structural system transformation in the Beishan orogenic belt during the Early Devonian has always been a key issue in the study of tectonic evolution in the region. In this paper, the granites from the Huangqiuquan area in the northern belt of Beishan is selected for petrology, zircon U-Pb chronology, element geochemistry and Hf isotope analysis. The results of zircon LA-ICP-MS U-Pb dating for the quartz monzonite and syenogranite are 412±2 Ma and 409±2 Ma respectively. The quartz monzonite and syenogranite in the research area were characterized by quasi aluminous to weakly peraluminous, alkaline to alkaline calcium and iron. The ΣREE is moderate, relatively enriched in LREE and depleted in HREE with weak to moderate fractionation between LREE and HREE. The quartz monzonite display small negative Eu anomalies, whereas the syenogranite show more obviously negative Eu anomalies. The trace elements are rich in Rb, K, U and poor in Sr, Ta, P and Ti. Calculated by zirconium saturation temperature, the crystallization temperature of Huangqiuquan granite is 828-888℃, average 856℃. Combined with the geochemical characteristics above, the Huangqiuquan granite should be defined as A-type granite. The zircon εHf(t) values ranges from -7.02 to - 4.42. tDM2 modle ages from 1.84 to 1.12 Ga, average 1.42 Ga. It indicates that the magma source area is mainly composed of ancient crustal materials, but there is also the addition of new biomass, which may be the product of the upwelling of depleted new mantle derived melts and varying degrees of magma mixing with ancient mafic crustal melts. The tectonic environment discrimination shows that the quartz monzonite is A2 type granite, and the syenite granite is A1 type granite. Based on regional geological data and previous research results, it is believed that the A-type granite in the Huangqiuquan area was formed in a post collision extension environment. The simultaneous occurrence of A1 type granite and A2 type granite indicates that the tectonic system of the Beishan orogenic belt entered a post collision extension environment during the Early Devonian and showed a trend of transition towards intraplate tectonic stage.