Details

Autor(en) / Beteiligte

• Zhao, L.
• Tang, H.
• Mitchell, R. N.
• Li, Q. L.
• Zhou, X. W.
• Zhai, M. G.

Titel

The Joining of North and South China During the Permian: Coherent Metamorphic Evidence From East Asia Orogenesis

Ist Teil von

• Tectonics (Washington, D.C.), 2023-08, Vol.42 (8), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2023

Quelle

Wiley Online Library

Beschreibungen/Notizen

• The joining of the North and South China blocks marks the formation of the united East Asian continent, which is an integral part of Pangea. The amalgamation of these two continental blocks also resulted in the formation of the world‐class ultrahigh pressure orogenic belt, namely the Dabie–Sulu orogenic belt. Figuring out the time of the initial collision between the two continents is critical for resolving questions such as the duration and the geodynamic processes of the orogeny. A Triassic joining time has been suggested by the geochronology of the eclogite facies rocks in this orogenic belt. However, paleomagnetic and paleontological studies suggested a Permian docking time for these continental blocks. In this paper, we present new metamorphic ages of rocks from northern Dabie and the Permo–Triassic intracontinental orogen of South China, which are all closely associated with this continental collisional event. New age dating results, as well as a synthesis of recent studies on metamorphic rocks occurring in southeastern North China and the Cathaysia Block of South China, show that the onset of the collisional orogenesis along the eastern part of the orogenic belt dates back to the Middle Permian (270–252 Ma). Considering these data and other geological records, we provide a new tectonic model for the major continents of East Asia, in which we show that the initial collision between North and South China occurred in the east during the Middle Permian, and then propagated westward. Continental collisions forming mountains and closing seaways in East Asia thus apparently occurred before the end‐Permian mass extinction, suggesting these paleogeographic changes might have also preconditioned and facilitated the end‐Permian biospheric crisis in the region. Plain Language Summary Orogenic belts are the loci of convergent plate interactions and they provide a window for observing Earth's deep crustal geodynamic processes. Metamorphic rocks in orogenic belts occur with varying metamorphic grades, whose temperatures, pressures, and ages are critical factors for understanding the history of plate interactions. Previous geochronological studies on eclogite facies rocks in the Dabie–Sulu orogenic belt, which is the result of the continental collision between North and South China blocks, have yielded mainly Triassic metamorphic ages. On the other hand, the paleomagnetic and paleontological data support an earlier collisional age during the Permian. This study targeted metamorphic rocks from the southern margin of North China, the northern Dabie orogen, and South China, all of which escaped deep subduction. They all show Permian metamorphic ages (270–252 Ma), which collectively indicate the Permian continental collision between North and South China. This new constraint on the initial continental collision between the two continental blocks is consistent not only with the paleomagnetic and paleontological data but also with the proposal of a diachronous collisional model for the Central China Orogenic belt with a westward younging trend. Key Points The continental collision between North and South China resulted in the formation of the East Asian continent within Pangea New geochronological results constraining the orogenesis reveal the onset of collision during the Permian The Permian collision might have also preconditioned and facilitated the end‐Permian biospheric crisis in the region