LA-ICP-MS zircon U-Pb dating of granite-porphyry from 358 Upland rock gold deposit in Wanda Mountain area, Heilongjiang Province and its geological significance

The 358 Upland rock gold deposit is located at the east edge of the Wanda orogenic belt, being part of the Circum-Pacific metallogenic belt. The authors selected the granite porphyry closely associated with mineralization in the study area to conduct a systematic study of geology, petrography, element geochemistry and LA - ICP-MS zircon U- Pb dating results. According to the results obtained, the granite porphyry is rich in silicon, sodium, potassium, aluminum and poor in magnesium and calcium, the Rittman index (σ) is 1.12 to 2.00（σ＜3.3）, A/NK=1.36~2.00，A/CNK=1.11~1.93 (A/CNK＞1.1). The granite-porphyry is enriched in LILE, relatively depleted in Ba, Nb and Ta, severely depleted in Sr, P and Ti; enriched in LREE, and depleted in HREE, with Eu anomalies. These characteristics reveal that the granite-porphyry is peraluminous, and the S type granite and magma might have been of shell source. LA-ICP-MS zircon dating methods were used to determine the age of the granite-porphyry. It is thus concluded that the gold metallogenic epoch should be late Early Cretaceous. Combined with the tectonic discrimination diagrams, the porphyry-granite shows the characteristics of post-collisional granite, and the formation of the porphyry might have been closely related to the post-collisional extension of the Pacific plate.