Thermal evolution of Cathaysian block along the south China margin since the Late Cretaceous: Evidence from low-temperature thermochronology

Hongcai Shi^1*Hui Xie^1*Weina Zhao²Tangwei Liu³Deming Kong¹Chuang Bao¹Lijie Liu³

• ¹Guangdong Province Key Laboratory for Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, China
• ²Northwestern Polytechnical University, Xi'an, Shaanxi Province, China
• ³East China University of Technology, Nanchang, Jiangxi Province, China

The Cathaysian Block has undergone complex tectonic transformation since the Mesozoic, with significant topographic and geomorphological changes due to large-scale magmatism, as well as tectonism in the central area. Apatite fission tracking (AFT) and zircon (U-Th)/He (ZHe) data were used to reveal the tectonic-thermal evolution history of the southeastern margin of the Cathaysian Block in the coastal region during the Late Cretaceous in this paper. Thermal history modeling indicated a multi-stage cooling history: (1) Widespread Late Cretaceous to Paleocene cooling across the entire coastal mountain. The Late Cretaceous cooling was coincident with rollback of the subducted paleo-Pacific Plate, which resulted in a negative inversion from compression to extension. (2A) rapid cooling beginning at ~ 60 Ma and at ~ 45 Ma, which was interpreted as temporally coinciding with continental rifting along the Cathaysian coastal margin, considered to have signaled the opening of the South China Sea (SCS); and (2B) a subsequent slow cooling stage with a small temperature change at ~ 50-65°C during the Oligocene to middle Miocene, accompanied by migration of the central rift to the marine basin. (3) A final stage of rapid cooling to surface temperature commencing about 18 and 10 Ma since the Miocene in response to multiple-plates interaction caused by the Tibetan Plateau uplift and the collision of the Philippine Block with the Eurasian continent.