A Distal Record of Large Hawaiian Submarine Landslides: the Lithology of Sediments Obtained From the Deep-sea Floor Adjacent to the Hawaiian Islands, KR01-K12 Cruise.

To understand the timing and emplacement processes of giant Hawaiian submarine landslide, a series of piston coring was performed in the adjacent area of Hawaii islands by R/V KAIREI, JAMSTEC in the summer of 2001. Long-distance volcaniclastic sediment transport generated by Hawaiian submarine landslides has been suggested by several previous studies (e.g. Garcia and Hull, 1994). Stratigraphical, sedimentological, and geochemical studies on the cores obtained by systematic sampling will make to understand for origins and ages of volcaniclastics emplacement to the ocean-floor. Nine cores were collected from the north of Oahu, the southwest and south of Hawaii Island, the south of Oahu. The major lithology is brown pelagic clay with abundant volcanic sand layers. Off Hawaiian Arch of the north of Oahu, pelagic clay with distinct 195cm-thick volcanic sand layer was recovered. The thick sand should be related to Nuuanu landslide, which debris avalanches were derived from Oahu Island. In the north of Haleakala rift, the alternation of brown colored clay and volcanic sand layer were obtained. Haleakala rift and Kohala slump are possible origins for these frequent occurrences of volcanic sand. In the south of Hawaii Island, we recovered alternations of volcanic sand and pelagic clay. The previous study suggested that volcaniclastic material in this area were derived from the Kilauea and older volcanoes of Hawaii Island. The obtained cores will provide stratigraphic information for volcanic history of Hawaii Island. The lower sequence below the alternation consists of radiolarian ooze, suggest the age of Eocene by on-board inspection. Two piston cores were obtained in the front of Waianae Landslide. The lithology of cores shows that the much volcaniclastics are interbeded in the upper sequence, and the massive clay in the lower.