Gaohua Zhu, Chinese University of Hong Kong, Earth System Science Programme, Hong Kong 999077, China, Hongfeng Yang, Chinese University of Hong Kong, Earth Science System Programme, Hong Kong, Hong Kong, Jian Lin, Woods Hole Oceanographic Inst, G & G, Woods Hole, MA, United States; Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China and Qingyu You, Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China