The Heyuan Fault, is one of the main NE-trending faults in the southernmost South China Block and is close to the northernmost South China Sea to the south. The fault features multi-stage deformation and controlled the formation of late Cretaceous to Cenozoic basins. Based on detailed field investigations and comprehensive geochronological research, including zircon U-Pb, Rb-Sr isochron, zircon U-Th-He dating, two episodic tectono-thermal events are recognized. The first occurred during ∼79 Ma to 66 Ma, which is characterized by large-scale quartz-fluid emplacement. The other occurred at ∼34 Ma, which features the eruption of a set of basalts. The two events show a changing on material source from siliceous hydrotherm to basalt magma, supporting obvious lithospheric thinning of the southernmost South China Block, which shed light on the geological evolution and the interaction mechanisms between the SCB and the northern South China Sea since the Late Cretaceous.

中文翻译：

---

华南地块晚白垩世和渐新世河源断裂两期构造热事件及其构造意义

河源断裂是华南地块最南端的主要北东向断裂之一，靠近南海最北端。该断裂具有多期变形特征，控制了晚白垩世至新生代盆地的形成。基于详细的实地调查和全面的地质年代学研究，包括锆石 U-Pb、Rb-Sr 等时线、锆石 U-Th-He 测年，确认了两个幕式构造热事件。第一次发生在～79 Ma 到 66 Ma 之间，以大规模石英流体侵位为特征。另一个发生在~34 Ma，其特征是一组玄武岩的喷发。这两个事件表明物质来源从硅质热液到玄武岩浆的变化，支持华南地块最南端的岩石圈明显减薄，