Recently, study on crystal morphology, internal texture, chronology and Hf-O isotopes of detrital zircons has been widely used for tracing sediments source. In the lower Mid-Proterozoic sediments, all the previous geochronological data suggest that the detrital zircon U-Pb ages from the Zhaertai Group and the Bayan Obo Group are mainly concentrated in the Late Neoarchean （～2.50 Ga） and the Late Paleoproterozoic （～1.90 Ga）. Moreover, the relative abundance of these two groups of detrital zircons show “oscillatory” changes in sequence. This characteristic is obviously in conflict with the age records from the tectono-sedimentary response in the typical source-to-sink system. In order to better understanding the relationship between the age distribution characteristics of detrital zircons in the Zhaertai-Bayan Obo rift sedimentary sequence and the tectonic evolution of the provenance area, in the study, a large number of previous relevant zircon ages are systematically compiled. In addition, the detrital zircon LA-ICP-MS U-Pb ages from the Shujigou and Zenglongchang Formations from the Zhaertai Group are carried out. The two age groups are consistent with the age of tectonic events recorded in the basement rocks of the Daqingshan-Wulashan orogenic belt. Morever, the detrital zircon internal texture shows that the～2.50 Ga zircons are derived from the Neoarchean magma-metamorphic terrane in the orogenic belt, while, the～1.90 Ga zircons come from the Paleoproterozoic high-grade metamorphic terrane. All the facts present here suggest that the near-horizontal interbedding of Neoarchean and Paleoproterozoic metamorphic rock series is the basic feature of the crustal structure in the lower orogenic belt, which is the direct reason for controlling the changes in detrital zircon assemblage in the basin, and the near-horizontal structural characteristics of the lower crust of the orogenic belt in the source area lead to the lithologic change rate in the vertical direction being much higher than that in the horizontal direction.
Liu Tongjun Liu Yongjiang Li Weimin Gao Fei. The characteristics of detrital zircons from the Zhaertai Group and Bayan Obo Group and its implications for the crustal structure of the provenance area[J]. Chinese Journal of Geology, 2020, 55(2): 459-486.