Sediment provenance records of the relationship between the southeast margin of the South China Block and Proto-Japan in the Late Triassic

Abstract

The South China Block (SCB) and Proto-Japan (includes Honshu, Kyushu, and Shikoku) are the important geological units in Eastern Eurasia. Their relationship in the Early Mesozoic is contentious, understanding it is crucial for understanding East Asia's evolutionary history and reconstructing the paleo-continent. We present a detrital zircon and provenances study of the Late Triassic Xiaoping Formation, the Genkou Group, and the Wenbinshan Formation on the southeast margin of the SCB. All have similar detrital zircon UPb age distributions, and three main age groups: 200–300 Ma, 400–500 Ma, and 700–1000 Ma. The primary provenances of the study area are the Yunkai Massif to the west, Hainan Island to the south, and northern Fujian, eastern Hunan, Wuyi Terrane, and Jiangnan Orogen to the north. The distribution of detrital zircons in the southeast margin of the SCB and Proto-Japan is further compared by applying various methods such as multidimensional scaling and Chi-square tests, which shows significant differences in the age distribution patterns of detrital zircons between the two areas. Further provenance analysis reveals significant differences between the southeast margin of the SCB and Proto-Japan during the Late Triassic, suggesting a lack of affinity between the two regions. Therefore, the Late Triassic Proto-Japan likely not located to the southeast margin of the SCB and moving closer to its current position.