Petrology and U-Pb geochronology of the serpentinite in the Lichi mélange of Eastern Taiwan and their tectonic implications

Lichi Mélange, located along the plate suture between the southeastern Eurasian Plate and the Philippine Sea Plate, is a research focus of the collision of the Luzon Arc with the Eurasian Continent. The serpentinite, as a key component of the Mélange, can provide important information for studying the arc-continent collision. Petrographic study suggests that the protolith of the serpentinite is peridotite and the zircon U-Pb chronology data reveals that the serpentinite was formed 17.7±0.5 Ma. The serpentinite or serpentinised peridotite is supposed to come from a forearc basin in the Manila subduction system, based on their ages and the evolution of the South China Sea and the Philippine Sea as well as their tectonic backgrounds, and became part of the mélange in the second thrust westward. The origin of serpentinite in the Lichi Mélange may provide detailed information and a reliable basis for the study of arc-continent collision orogenic activity and plate tectonic movement.