2. International Centre for Geoscience Ｒesearch and Education in Northeast Asia，Jilin University，Changchun 130026，China

Daerlongcun area of the Jiamusi Block have been presented，with the aim of evaluating their formation age，petrogenesis and tectonic setting． The studied granitoids are composed mainly of granodiorite and alkali-feldspar granite．

The LA--ICP--MS zircon U--Pb dating shows that the granodiorite and alkali-feldspar granite formed during the Early Paleozoic，with ages of 531 Ma and 501 Ma，respectively． Geochemically，they are characterized by high concentrations

of SiO2 ，Na2O + K2O，but low concentrations of total Fe2O3 ，CaO and MgO． They are enriched in large-ion lithophile elements ( LILEs; e. g. ，Ｒb，K) and high-field-strength elements ( HFSEs; e. g. ，Th，U) ，but depleted in HFSEs ( e. g. ，Nb，Ta，Ti) and P． The granodiorite and alkali-feldspar granite belong to the middle-high-K calc-alkaline I-type and highly fractionated I-type granites，respectively． Both of them were derived from the partial melting of a lower crust and subsequently underwent some degrees of fractional crystallization processes． Along with the regional geological data，the authors propose that the Early Paleozoic magmatic rocks in the Jiamusi Massif were emplaced in a post-collisional extensional setting，which was closely related to the collapse of the thickened crust

after the peak granulite facies metamorphism．