1. College of Earth Sciences��Jilin University��Changchun 130061��China; 2. Geological Survey Institute of Yunnan Province��Kunming 650051��China

On the basis of systematical studies of Laozuoshan gold deposit��the geochemical analyses (inclu- ding major and trace elements) were further undertaken for the ore-related rocks�� The results show that the ore- related granites are low Ti and high Sr in content��belonging to High-K calcalkaline volcanic arc granites��while the diorite porphyrite appears the feature of metaluminous calc- alkaline rock series�� All the rock samples are character- ized by enrichment in light rare earth elements (L��EEs) and large ion lithophile elements (LILEs)��and relative depletion in heavy rare earth elements (H��EEs) and high field strength elements (HFSEs)��such as Nb��Ta and Ti��with affinities to the igneous rocks formed in island arc or active continental margin settings�� The features of fluid inclusions indicate that the ore- forming fluid mainly came from magmatic water��and the deposit was characterized by formation in the low- medium depth (1.0��7.1 km) under low-medium temperature (125. 6�棭324. 5��)�� Notably��the ore- related magmatic rocks show the characteristics of mantle- derived magma��suggesting that they were likely produced by partial melting of mantle experienced in metasomatism�� According to the distribution of the coeval igneous rocks in the area��it is proposed that the formation of Laozuoshan gold deposit may be closely related to the Late Paleozoic northward subduction of the Paleo- Asian oceanic plate and the Mesozoic westward subduction of the Pacific oceanic plate��respectively��