Abstract:

The siliceous rock zone in Yantong mountain area,central Jilin Province,is the key region for studying the paleoAsian ocean tectonic evolution. The predecessors confirm that piedmontite siliceous rock exists in this area, and combining with the research of peripheral rock characteristics, the paper suggests that this area should be the site of the final closing of the paleo-Asian ocean. According to the lithochemical analysis, the authors find the parent rocks of silicalite are volcanos. In the zircons CL image, the rhythm annulus structure of ziron is obvious,which shows that they are the earlier magma rock zircons. LA-ICP-MS single-zircon U-Pb isotopic age dating indicates the siliceous rock deformation and metamorphism took place at (239±11)Ma.Combining with the metamorphism age of Hulan Group, the authors confirm that the final closing of the paleo-Asian ocean took place in the Mesozoic(Triassic).

Key words: central Jilin, siliceous rock, zircon dating, paleo-Asian ocean, Mesozoic