To obtain the major and trace element contents of seep carbonate, samples were ground into powder and send to the SampleSolution Lab, Wuhan, China. 100 mg powder sample was reacted with 5 volume% acetic acid under 60 °C for 24 hours. The solution was then treated twice in ultrasonic bath for 30 minutes and, subsequently, centrifuged at 4000 r/min for 10 minutes. A certain amount of supernatant was dried at 105 °C. The residue was dissolved with concentrated nitric acid and then dried to remove acetic acid. After the new residue was fully dissolved with concentrated nitric acid at 80 °C for 2 hours, the obtained solution was diluted to suitable concentration and measured with an Agilent 7700e ICP-MS.

Yang Lu gratefully acknowledges the support of K. C. Wong Education Foundation and DAAD. U-Th dating was supported by grants from the National Taiwan University (NTU) Core Consortiums Project (112L894202), Higher Education Sprout Project of the Ministry of Education (112L901001).