ZIRCON LA-ICP-MS U-Pb DATING AND ITS IMPLICATION OF UPPER PERMIAN LINXI FORMATION IN JARUD QI, INNER MONGOLIA

The study area is located in the north of Xar Moron River-Changchun-Yanji fault where the huge thick Upper Permian Linxi Formation is developed, with the lithologic assemblage of gray, grayish black and yellow-green sandy slate. The research on its chronological characteristics is of important significance for determination of the geotectonic setting. The authors analyze the sandstone samples from Linxi Formation with zircon LA-ICP-MS U-Pb dating. The results show that the ages are distributed in 5 age ranges: 252-300 Ma, 305-423 Ma, 431-555 Ma, 600-999 Ma and 1037-2460 Ma. The youngest age of 252 Ma indicates the lower limit of sedimentary time for Linxi Formation. The study above shows that the provenance of Late Permian Linxi Formation in Jarud Qi area reflects the information of both the metamorphic basement and following tectonomagmatic event in Northeast China and the northern margin of the North China Plate, suggesting that the Linxi Formation completed the final collision and collage along the northern margin of the Xar Moron River suture zone between North China Plate and the blocks on north in the Late Permian.