College of Earth Sciences��Jilin University��Changchun 130061��China

To discuss the connection of the formation of Shihu gold deposit with Mapeng granite rock mass and quartz-diorite porphyrite dike��the authors study the U --Pb chronology of granodiorites and quartz-diorite porphy- rites��and analyze the geochemistry of granite diorites��quartz-diorite porphyrites��mineralized alteration rocks and wall rocks��respectively�� The U--Pb zircon age of Mapeng granite is (124. 8 ±1. 4) Ma (MSWD =0. 74) and the age of dioritic porphyrite dike is (127. 3 ±1. 1) Ma (MSWD =1. 15)�� But there are significant differences in their geochemical characteristics��which indicate different origins of them�� Geochemical characteristics show that Mapeng granodiorites and mineralization-alteration rocks have a relatively concordant distribution pattern of rare earth and trace elements��but they are different in wall rocks�� It is proved that the origin of ore-forming fluids of Shihu gold deposit is close to that of Mapeng granodiorites�� Besides��Mapeng granodiorites have high potassium and calcalka- line��which is rich in L��EE and deficient in H��EE with weak Eu negative anomaly�� The high Sr/Y and La/Yb ra- tios show that Mapeng intrusion is formed by mantle-derived magma mixed with granite magma�� The mantle-derived magma invasion and mixed with granite magma that provides the ore-forming fluid and ore-forming materials�� Map- eng intrusion is the carrier of ore-form fluids and materials�� Combined with the features of the ore deposit geology�� the study first proposed that dioritic porphyrite dikes are closely related to ore bodies in temporal and space��that should owe to the diorite porphyry dikes as impermeable layers��which have a certain sealing effect on the ore-form- ing fluids from the Mapeng intrusions and lead to the enrichment of mineralization and alteration near these dikes�� that is��dike closure effect�� Shihu gold deposit formed during lithospheric thinning and craton destruction of Meso- zoic��and it should be a kind of an orogenic gold deposits��