Abstract:The amalgamation timing of the Xing’an and Songneng Blocks is still on controversy. The Xinsheng, Xinli and Niuqiuhe intermediate to felsic plutons in the southeast of Xing’an Block were systematically studied using geochronology, petrology and geochemical analysis, with the aim to understand its tectonic and magmatic evolution during the Late Paleozoic. Zircon LA- ICP- MS U- Pb dating results suggest these plutons formed in the Late Carboniferous (315~298 Ma). The Xinli monzogranite has a zircon U- Pb age of 304±2 Ma. The Xinsheng monzogranite and monzonite formed at 312±2 Ma and 303±2 Ma, respectively. The Niqiuhe alkali- feldspar granite and gabrroic diorite were formed at 315±2 Ma and 298±6 Ma, respectively. Geochemical analysis shows that these rocks are high- K calc- alkaline/shoshonite series and metaluminous. The Niuqiuhe gabbroic diorite has high MgO content (68%~8%) and Mg values (64~68), low Al2O3 and TiO2 contents, with affinity of sanukite. The Niqiuhe alkali- feldspar granite has high SiO2 and K2O and low CaO, rich in LREE and LILEs and depleted in Eu, which belongs to A2- type granitoids. The Xinli monzogranite and Xinsheng monzogranite are rich in SiO2, strong REE differentiation, and moderate depletion in Nb, Ta, P and Ti, suggesting the characteristics of highly fractionated I- type granitoids. Furthermore, the Xinsheng monzogranite is characterized by high Sr/Y ratios (132~140). The Xinsheng monzogranite and Niqiuhe alkali- feldspar granite formed likely from partial melting of the lower crust, while the Xinsheng mozonite and Xinli monzogranite were hybid melts by crust- mantle derived magma mixing. The Niqiuhe gabbro diorite originated from slab- derived sediment metasomatized mantle. According to the geochemical difference between Early Carboniferous and Late Carboniferous magmatism, along with regional geological data, it is deduced in this study that the Xing’an and Songnen Blocks had amaglmated together before 315 Ma and these Late Carboniferous intrusions formed in a post- collisional setting.