The Geology and zircon SHRIMP U-Pb dating of the Haigou complex in Antu County, Jilin Province which was proposed to be Mesoproterozoic strata in previous researches was reported in this article. The new data suggest that the different units in the Haigou complex show variable metamorphic grades and formation ages. The Sichazi Formation which is characterized by banded iron formation show upper-amphibolite facies metamorphism and anatexis. A trondhjemite gneiss which intruded into the BIF in the Sichazi Formation yielded formation age of 2 554 ± 3 Ma and metamorphic age of 2 528 ± 11 Ma. This age suggests that the Sichazi Formation is older than 2 554 Ma and is proposed be Neoarchean supracrustal rocks according to the correlation with other areas. However, the Dongfanghong Formation show strong deformation, but only show greenschist facies metamorphism. One meta-rhyolite in Dongfanghong Formation yielded formation age of 178 ± 2 Ma. This age suggests that the rhyolite is an Early-Jurassic volcanic rock with younger deformation. New data suggested that the Haigou complex is not suitable for a lithostratigraphic unit and should be disintegrated and redefined since it includes both Archean basement and deformed Mesozoic strata. The Archean rocks occurred as tectonic slices among the Phanerozoic rocks during the closure of Paleo-Asian Ocean at the end of Paleozoic-beginning of Mesozoic in the northeastern margin of North China Craton and post-orogen tectonic events. The metamorphic zircons which occur as either single grains or overgrowth rims surrounding magmatic cores in the dated trondhjemitic gneiss yielded very high Th/U ratio, and was suggested to be related to the formation of high-U minerals during metamorphism. The examples of high Th/U metamorphic zircons and low Th/U magmatic zircons suggested that the Th/U ratios of zircons only can be used as an assistant tool but not a critical tool during determining the origin of zircons.
Xie Hangqiang Wan Yusheng Zhou Xiaodong Ren Peng Li Yuan. The disintegration of Haigou complex in Antu County, Jilin Province: Evidence from geology and zircon SHRIMP U-Pb dating[J]. Chinese Journal of Geology, 2017, 52(4): 1140-1159.