Strontium isotope stratigraphy and LA-ICP-MS U-Pb carbonate age constraints on the Cenozoic tectonic evolution of the southern South China Sea

The tectonic evolution of the South China Sea is closely associated with multiple sub-duction-collision processes in Southeast Asia. When the collision of the Dangerous Grounds terrane with Sabah-Palawan Is-lands terminated is debated due to poor age constraints at the southern margin of South China Sea. A deep well drilled on Meiji Atoll penetrates Cenozoic carbonate strata in central Dangerous Grounds. Robust stron-tium isotope ages and laser ablation-induc-tively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dates provide critical chronological constraints on the Cenozoic evolution of the southern South China Sea. A middle Miocene hiatus spanning 9 m.y. on Meiji Atoll is thought to be mainly caused by tectonic uplift in the central Dangerous Grounds. The uplift in the central Danger-ous Grounds was accompanied by under -thrusting beneath the southern Palawan margin and orogenic uplifting in north Bor-neo during the middle Miocene. Data inter-pretation indicates an active collision in the southern South China Sea during the middle Miocene. The regrowth of the Meiji Atoll above the middle Miocene hiatus represents the end of this collision event in the southern South China Sea at ca. 11 Ma, after the ces-sation of seafloor spreading, which occurred at ca. 15 Ma.

Automated summary

This study provides important chronological constraints on the Cenozoic evolution of the southern South China Sea by determining the end time of the collision between the Dangerous Grounds terrane and the Sabah-Palawan Islands. The results indicate an active collision event in the southern South China Sea during the middle Miocene.