LA-ICP-MS U-Pb ages of zircons from metamorphic basalt and metamorphic accumulated gabbro in Yilan area, Heilongjiang Province, and their geological implications

In this study, LA-ICP-MS zircon U-Pb method was used to study the geochronology of metamorphic basalt, metamor-phic pillow basalt and metamorphic accumulated gabbro of Heilongjiang complex in Yilan area. The results obtained demonstrate that many zircons in metamorphic basalt originated from basal rocks and their distribution of ages are wide, with their geochronologi-cal ages varying between 3172±24Ma and 176±1Ma. The age of plane textural zircon is 243Ma, which represents the original rock formation age of the metamorphic basalt. Concordant ages of the metamorphic pillow basalt and metamorphic accumulated gabbro are 251±1Ma and 252±1Ma respectively, which represent the formation ages of their original rock. Zircon U-Pb geochronological results demonstrate that an ancient oceanic basin existed between Jiamusi block and Songnen-Zhangguangcailing block during Late Permian. The results obtained by the authors provide important geochronological evidence for studying the tectonic evolution of the Heilongjiang complex.