LA-ICP-MS ZIRCON U-Pb AGE OF BASALT DIKES IN XINGCHENG OF LIAONING, NORTH CHINA CRATON: Geologic Implications

Affected by the subduction of Paleo-Pacific plate in Mesozoic, large-scale lithosphere thinning took place in North China Craton, leading to the significant changes of its physical and chemical properties. To reveal the mechanism of craton thinning and constrain the timing of craton destruction becomes a major scientific problem for geologists. The Mesozoic basalts are widely developed in North China Craton. As the product of magmatism, basalt contains geochronological information that can provide important timing constraint for lithosphere evolution. The Archean-Meso-Cenozoic magmatic rocks developed in Xingcheng area of Liaoning Province in the northern margin of North China Craton are ideal objects for studying the destruction of North China Craton. Although lots of research has been done on these basalts, their end time is still disputed. The Xingcheng basalt dike is selected as the research object, and LA-ICP-MS zircon U-Pb chronology and rutile U-Pb chronology are studied to discuss the diagenetic chronology and its geological significance. The zircon U-Pb dating results show that the age of Xingcheng basalt dike is 104.8 ±6.5 Ma, and the end age of Mesozoic lithosphere thinning in North China Craton can be inferred to about 105 Ma. The chronological information provides constraint on the timing of large-scale lithosphere thinning process in North China Craton in the late Early Cretaceous.