Low-temperature thermochronology data from the eastern South China Block
decipher episodic subduction of the Paleo-Pacific Plate
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.