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Low-temperature thermochronology data from the eastern South China Block decipher episodic subduction of the Paleo-Pacific Plate
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  • Jinghua Wu,
  • Huan Li,
  • Martin Danišík,
  • Kotaro Yonezu,
  • Han Zheng,
  • Zhihan Li
Jinghua Wu
Central South University
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Huan Li
Central South University

Corresponding Author:[email protected]

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Martin Danišík
Curtin University
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Kotaro Yonezu
Kyushu University
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Han Zheng
Central South University
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Zhihan Li
Central South University
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Abstract

Mesozoic subduction of the Paleo-Pacific Plate triggered intense tectonism, magmatism, and metallogeny in the eastern South China Block (E-SCB) and set off long-term tectonic, topographic, and climatic responses. However, contrasting hypotheses have been proposed to interpret the timing, style, and evolution of this oceanic subduction. Unraveling the exhumation history of the E-SCB is crucial to understanding deep subduction processes. To address the poorly documented exhumation history of the E-SCB, we present first zircon and apatite (U-Th)/He dates from eight Mesozoic granitoids distributed in a lateral profile across the intracontinental E-SCB. These data are combined with a compilation of regional thermochronological data, in order to address the evolution of the E-SCB in a tectonic, topographic, and climatic evolution framework. Zircon and apatite (U-Th)/He central ages of the investigated plutons range from 146–30 Ma and 82–31 Ma, respectively, implying long-lived exhumation of the intracontinental E-SCB. Inverse thermal modelling indicates the intracontinental SCB underwent multi-phase exhumation events from the Jurassic, despite variable onset timing and the fact that the far intracontinental E-SCB had been an exhumation center prior to the Early Cretaceous. In addition, a compilation map of regional thermochronological data reveals propagation of the exhumation center from the intracontinental to the epicontinental E-SCB over time (from the Cretaceous to the Paleogene). Based on these results, we propose a refined model of Paleo-Pacific Plate subduction since the Triassic. This model is in good agreement with geological observations in the E-SCB and capable of explaining regional magmatism, metallogeny, tectonism, and exhumation.