辽西东南部中生代花岗岩时代

The southeast part of the Western Liaoning Province (Liaoxi) is one of the important areas in the North China Craton in which the Mesozoic granitic magmatism was intensively developed. The well-known Yangjiazhangzi Mo deposit is located in this area. However, the emplacement ages of these granites are not well constrained. Based on the intensive field investigation and systematic sampling, zircon U-Pb isotopic analyses were conducted for various rock types in this area. The obtained U-Pb geochronological data indicate that the Jianchang-Yangjiazhangzi batholiths were emplaced mainly 180 - 190 Ma with some part formed in 150 - 160 Ma. The Haitangshan-Yiwulvshan batholiths in the eastern part were emplaced in 150 - 170 Ma. Therefore, it is concluded that the Jurassic is the main period of the granitic magmatism in area, whereas the Cretaceous granitic magmatism is limited. These data also suggested that the Yangjiazhangzi Mo deposit was formed in the Middle Jurassic, and the Waziyu metamorphic core complex was developed in the early Cretaceous. Comprehensive data compilations of the igneous rocks in the Yanshan-Liaoxi area display that the ages of the granites are not comparable to those of the volcanic rocks. However, a westward youngling trend was found for the Mesozoic granitic magmatism in the Yanshan-western Liaoning area. The inherited zircons indicate that the Early Precambrian magmatisms were developed mainly in the 2.5 and 1.85 Ga.