ZIRCON U-Pb DATING AND GEOCHEMISTRY OF THE VOLCANIC ROCKS OF TAMULANGOU FORMATION IN THE SOUTH EDGE OF MOHE BASIN: Geological implication

The paper studies the zircon LA-ICP-MS U-Pb dating and lithogeochemistry of the Mesozoic basaltic andesite of the Tamulangou Formation from the south edge of Mohe Basin in Northern Daxinganling to define its formation age and the relation between volcanic activities and the evolution of Mohe fault basin. The dating result shows that the age of the basaltic andesite ranges from 129 to 147 Ma, belonging to Early Cretaceous. The volcanic rocks of the Tamulangou Formation are mainly of high-K calc-alkaline series, with enrichment in large ion lithophile elements(LILEs)and light rare earth elements (LREE) and depletion in high field strength elements (HFSEs). The magmatic source of the volcanic rocks was originated from partial melting of enriched mantle and probably contaminated by upper crustal materials during the ascending. The geochemical characteristics and tectonic background indicate that the volcanic rocks of the Tamulangou Formation was formed in a continental intraplate extensional environment, and related to the Mesozoic faulted structure of the Mohe Basin.