Geodynamics of Late Mesozoic Magmatism in the Eastern South China Block: An Overview

In this paper, we review the petrological and geochemical studies of the late Mesozoic igneous rocks in the eastern part of South China (mainly the southeast coastal area) conducted by our group during the past five years, focusing mainly on the geodynamic process of the Cretaceous magmatism. The main advancements include: (1) The late Mesozoic mafic magmatism in South China recorded the geodynamic processes from subduction to rollback and tearing of the paleo-Pacific slab. During these processes, the mantle sources for the mafic magmas were enriched by the subducted sediments of the upper oceanic crust during the advanced subduction and were then metasomatized by the lower oceanic crust in response to the slab retreat and tearing. (2) The crustal sources for felsic volcanic rocks changed from the low-temperature (700–810 °C) water-rich crust in the advanced subduction stage to the high-temperature (790–860 °C) water-poor continental crust in the rollback-tearing stage. (3) The late Mesozoic crust in the southeast coastal area experienced extensive crustal accretion and subduction-induced replacement, forming the ‘equal-isotope’ and petrochemically bimodal intrusive complexes. We propose that the slab subduction-rollback-tearing model may also be applicable to the geodynamics of the early Mesozoic tectonic-magmatic evolution in the eastern South China Block. © 2022 Science Press. All rights reserved.