U-Pb ages, trace elements and Hf isotopes of detrital zircons from the late Permian-early Triassic sedimentary succession in the northern Yangtze Block, South China: Implications for the reconstruction of the South China Block in Pangea

Abstract

It is thought that the North China Block collided with Pangea earlier than the closure of the Mianlue Ocean between the South and North China Blocks. Therefore, the closure of the Mianlue Ocean, which induced the formation of the Qinling-Dabie Orogen, led to the amalgamation of the South China Block and Pangea. Yet, the timing of closure remains poorly constrained. We present detrital zircon U-Pb ages, trace element and Hf isotopic data for an upper Permian-lower Triassic sedimentary succession in the Western Hubei Basin, northern Yangtze Block, South China. One major age population of 250–330 Ma and four minor age populations of 400–650 Ma, 1030–1300 Ma, 1600–2000 Ma and 2300–2800 Ma were identified. Trace element and Hf isotopic data indicate zircons in the major age population may have sourced from active continental margins. When integrated with tectono-magmatic events of adjacent blocks, our data support that these detrital zircons were mainly sourced from the Qinling Orogen in the southern North China Block. Combined with continental subduction-related metamorphic events in the Dabie Terrane and syn-collisional granitoids in the West Qinling Belt, as well as the paleomagnetic data, our data support that the Mianlue Ocean experienced a scissors-like closure from the Late Permian in the east to the Middle Triassic in the west. In the middle of the Qinling-Dabie Orogen, the closure of the ocean took place earlier than ~255 Ma. This study supports the hypothesis that the South China Block became a part of Pangea during the Late Permian-Middle Triassic.