ZIRCON U-Pb GEOCHRONOLOGY OF BASHENGHE PLUTON IN NORTHERN DAXINGANLING MOUNTAINS: Geological Implications

The Bashenghe pluton in Zhalantun area of northern Daxinganling Mountains is composed of alkali-feldspar granite. The zircon LA-ICP-MS U-Pb dating yields the weighted mean age of 297.8±3.6 Ma, indicating the pluton was formed in the Early Permian. The whole rock geochemistry of 4 samples shows that the alkali-feldspar granite is characterized by rich Si, high K and rich alkali, belonging to weak peraluminous shoshonite series. The characteristics of high ∑REE, obvious negative Eu anomalies and enrichment of LILEs are properties of A-type granite. Combined with previous research results and isotopic chronology, it is concluded that the convergence of Xing'an massif and Songnen massif occurred before 298 Ma.