摘要
The SHRIMP U-Pb zircon dating result of the Tongshi magmatic complex in western Shandong is presented in this paper. The Tongshi magmatic complex comprises fine-grained porphyritic diorite and syenitic porphyry. Eighteen analyses for fine-grained porphyritic diorite gave two concordia ages, in which ten analyses constitute the young age group, giving ^206Pb/^238U ages ranging from 167.9 Ma to 183 Ma with a weighted mean age of 175.7±3.8 Ma, and the other eight yielded ^207Pb/^206Pb ages of 2502 Ma to 2554 Ma with a weighted mean 2518±11 Ma. Two analyses for syenitic porphyry gave ages of 2485 Ma and 2512 Ma, respectively. The age of 175.7±3.8 Ma indicates that the crystallization of the Tongshi magmatic complex occurred in the Middle Jurassic, whereas that of 2518±11 Ma is interpreted as the age of inherited magmatic zircons in the Neoarchean Wutai period.
The SHRIMP U-Pb zircon dating result of the Tongshi magmatic complex in western Shandong is presented in this paper. The Tongshi magmatic complex comprises fine-grained porphyritic diorite and syenitic porphyry. Eighteen analyses for fine-grained porphyritic diorite gave two concordia ages, in which ten analyses constitute the young age group, giving ^206Pb/^238U ages ranging from 167.9 Ma to 183 Ma with a weighted mean age of 175.7±3.8 Ma, and the other eight yielded ^207Pb/^206Pb ages of 2502 Ma to 2554 Ma with a weighted mean 2518±11 Ma. Two analyses for syenitic porphyry gave ages of 2485 Ma and 2512 Ma, respectively. The age of 175.7±3.8 Ma indicates that the crystallization of the Tongshi magmatic complex occurred in the Middle Jurassic, whereas that of 2518±11 Ma is interpreted as the age of inherited magmatic zircons in the Neoarchean Wutai period.
基金
This study was supported by the Major State Basic Rsearch Program of China(grant G1999043211)
National Natural Science Foundation of China(grant 40272088).
