Abstract:The Hulalin gold deposit in the Upper Heilongjiang Basin is located in the northern margin of the Erguna micro-block in the northern Daxinganling, east of the Xingmeng orogenic belt, and is bounded between the Mongolian-Okhotsk suture zone and the Deerbugan fault. The orebodies occur mainly in the cryptoexplosive breccia, which is closely related to the granite porphyry and quartz porphyry formed by the Early Cretaceous magmatism. Using LA-ICP-MS zircon U-Pb dating method, this study obtained a crystallization age of 141.7±1.1Ma (MSWD=0.086) for granite porphyry, and two crystallization ages of 144.86±0.56Ma (MSWD=0.580) and 142.6±0.74Ma (MSWD=0.077) for two samples of quartz porphyry, both of which were products of early Cretaceous magma activity. The zircon ?Hf(t) values of granite porphyry and quartz porphyry are -4.14 ~ 0.16 and -2.25 ~ 1.37, and most of the data falls below the chondrite evolution line. The two-stage model ages (tDM2) of the two rocks are 987.08~1259.04 Ma and 908.38~1138.56Ma, respectively. The lithogeochemical characteristics show that the granite porphyry has w(SiO2) of 66.21% ~ 66.70%, w (Al2O3) of 15.18%~15.45%, and w(Na2O+K2O) of 7.56% ~ 8.17%, and aluminum saturation index A/CNK of 1.03~1.06, showing weak aluminum high potassium calc-alkaline-potassium rock series. Quartz porphyry has w(SiO2) of 66.34% ~ 68.25%, w(Al2O3) of 13.77% ~ 15.05%, and w(Na2O+K2O) of 6.76% ~ 9.06%, all of which fall in the potassium basalt area of the SiO2-K2O diagram. Granite porphyry and quartz porphyry has total REEs contents of 71.07×10-6~97.92×10-6 and 135.53×10-6~156.15×10-6 respectively, and (La/Yb)N of 24.87~26.81 and 31.33~40.62 respectively, all of which show the relative enrichment of LREE and the relative depletion of of HREE, with distinct fractionation of LREE and HREE. The both rocks have δEu values of 0.65 ~ 0.88 and 0.41 ~ 0.50 respectively, with the latter more abnormal than the former. Both rocks are relatively enriched in incompatible elements such as Rb, K and other large ion lithophile elements (LILEs), LREE and U, and strongly depleted in Nb, Ta, Ti, P and other high field strength elements (HFSEs). The petrogenetic discriminant diagram shows that the Early Cretaceous intrusive rocks of the Hulalin in the Upper Heilongjiang Basin are I-type granite, and formed in the post-collisional setting of Mongolia - China and North Korea continent and the Siberian continent. In such a tectonic setting of transition from compression to extension, the rocks formed from detachment and partial melting of thickened ancient crust due to the continent-continent collsion of Mongolia-Okhotsk orogenic belt, contaminated by mantle material or newly born crust. This further indicates that the Mongolian-Okhotsk ocean was closed completely before 144.9Ma at least.