On December 1, the survey vessel Haiyang Dizhi 6 (Marine Geology 6) of the Guangzhou Marine Geological Survey, China Geological Survey, returned to Guangzhou after completing the second leg of the 15th deep-sea geological survey expedition. The cruise departed on August 29 and lasted 95 days, covering a total of 12,673 nautical miles, and produced a series of results in deep-sea environmental surveying and in the application of key deep-sea exploration technologies and equipment.
First, the expedition acquired a body of marine environmental data along with samples of deep seawater, seabed sediment, polymetallic nodules and marine organisms, providing basic support for deep-sea geological research and marine environmental management.
Second, the application of key deep-sea exploration equipment made new progress: for the first time in Pacific deep water, a 6,000 meter class remotely operated vehicle (ROV) and an autonomous underwater vehicle (AUV) carried out joint high-precision near-bottom test operations.
Third, the expedition carried out seabed mineral geological survey work and identified one polymetallic nodule enrichment area.
Fourth, in the central rift of the western Pacific, the cruise completed the sea trial of seabed electromagnetic receivers developed under a project of the national key research and development program for the 14th Five-Year period, conducting the first electromagnetic profile measurement in a Pacific hadal zone, with a maximum deployment depth of 7,663 meters. The high-quality electromagnetic data obtained will support future research on the evolution of the Earth’s deep structure and on site selection for ocean scientific drilling.
In addition, the cruise introduced hydroponic cultivation on board for the first time, which, combined with the ship’s existing soil-based planting, kept the crew supplied with fresh vegetables for the entire voyage, offering a useful reference for improving living conditions on long ocean research cruises.
