1. China University of Petroleum (East China), School of Geosciences, Qingdao, China; China University of Petroleum (East China), Key Laboratory of Deep Oil and Gas, Qingdao, China; and Qingdao National Laboratory for Marine Science and Technology, Laboratory for Marine Mineral Resources, Qingdao, China.
2. China University of Petroleum (East China), School of Geosciences, Qingdao, China; China University of Petroleum (East China), Key Laboratory of Deep Oil and Gas, Qingdao, China; and Qingdao National Laboratory for Marine Science and Technology, Laboratory for Marine Mineral Resources, Qingdao, China. (corresponding author)