To obtain the carbon and oxygen isotope compositions of seep carbonate, samples were ground into powder and send to the Fujian Normal University. About 1 mg powder was reacted with a few droplets of phosphoric acid under 70 °C for two hours. The CO₂ from the carbonate was purified and measured with a Gasbench attached to a Thermo MAT 253 mass spectrometer.

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).