The 358 Upland rock gold deposit is located at the east edge of the Wanda orogenic belt, being part of the Circum-Pacif-ic 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 re-sults 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 porphy-ry-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.%选取黑龙江省完达山地区358高地与成矿关系密切的花岗斑岩,进行系统的地质、岩相学、元素地球化学及LA-ICP-MS锆石U-Pb定年研究.结果显示:花岗斑岩具有富硅、钠、钾、铝,贫镁、钙的特征,里特曼指数(σ)为1.12~2.00(σ<3.3),A/NK为1.36~2.00,A/CNK为1.11~1.93 (A/CNK>1.1);富集大离子亲石元素,亏损Nb、Ta,严重亏损Sr、P、Ti;轻稀土元素富集,重稀土元素亏损,具有负Eu异常.这些特征揭示,花岗斑岩是过铝质的S型花岗岩,岩浆来源可能为壳源.LA-ICP-MS锆石定年获得花岗斑岩的成岩年龄为128±1Ma,推断金矿成矿时代应为早白垩世晚期.构造判别图解显示,花岗斑岩具有碰撞后花岗岩的特征,斑岩体的形成很可能与太平洋板块俯冲作用后的伸展体制有密切关系.
展开▼
