4-2. Northeast of Hawaii (PC-9 and PC-10) 　　　　　　　　　　

Objectives
There are several potential sources for landslide debris in the area northeast of Hawaii island. Moore et al. (1989) mapped two large landslides there based on GLORIA data: Hana landslide, off the east flank of Maui, and Pololu landslide, which heads east off the northern tip of Hawaii island. In addition, Smith et al. (2001) propose that a landslide may have formed the scarp-like amphitheatre at the distal eastern end of Hana ridge, thought to be the east rift zone of Haleakala volcano (HERZ). Smith et al. also propose that Pololu landslide is smaller than previously suggested, and that it is underlain by an older, larger landslide, termed Laupahoehoe; both of these are thought to have occurred off the flanks of Kohala volcano. No ages are known for any of these events, and piston cores offshore of this complex area may provide both information about timing of catastrophic landslides, as well as information about the geochemical evolution of Haleakala and Kohala volcanoes. PC9 was recovered 130 km NE of Hawaii, and PC10 was 150 km E of the NE coast of Hawaii island. PC9 and PC10 will be studied in conjunction with dives during Leg 2a on Hana Ridge, Laupahoehoe slump, and Hilo Ridge. The dives should provide information about source rocks for landslide events that maybe recorded in the piston cores.

Lithology
Core P9: Moderate brown clay mottled with volcanic sand, and frequent inter-beds of volcanic silt and sand layers between (sec 2- sec 4), 21-53 cm are observed. thick sand layer in sec 6. Inter-bed several volcanic sand -silt layers are observed in sec 7-8. The sand layer in the interval of 15-35 cm in sec 9 shows upward fining.

CoreP10: Sec. 1, 2 and 3 are characterized by the diatomaceous ooze mottled with volcanic sand. 0-45cm of sec 4 is laminated silt. The interval between sec 5 and 45cm of sec 7consists of moderate brown clay with several interbedded volcanic silt layers. From 45 cm, sec 7 to 57 cm, sec 8, a very thick massive sand is normally graded at its base and bears foraminifera. In-flow mud comprises the bottom 250 cm of the core.
On board MS can be used to make a preliminary correlation between PC9 and PC10. A small peak in MS in PC9 70 cm from the top of sec 1 is very similar in magnitude and shape to a peak in PC10 130 cm from the top of sec 1. This is consistent with the presence of diatomaceous ooze at the top of PC10 which is absent in PC9. From the peak mentioned above, the MS profiles of the two cores are similar for the next ~350 cm. The bottom portions of the cores are dissimiliar in lithology and susceptibility profiles. These results suggest that the cores share the recent portion of their depositional histories, but not the earlier portions.

　　　　　　　　　　　　 　　　　　　　　　　　　

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