Geophysical Observations between Hawaii and Australia

Abstract

A 3.5 kHz high resolution profiling system and a sparker seismic system were utilized along a geophysical traverse from Hawaii to Australia. The delineated sediments range from a total lack of sediment cover on the axis of Woodlark Basin spreading center to a thick pile of biogenic debris beneath the equatorial high productivity zone. The calcareous oozes of the western Darwin Rise and Solomon Rise, the interbedded clays, silts, and volcanic debris of the Hawaiian Arch, and local sediment pockets near topographic highs are discerned by the 3.5 kHz energy source as stratified. The nonfossiliferous deep-sea lutites (red clays) and siliceous oozes in the deeper portion of the central Pacific appear as acoustically transparent sediments. Erosion and redeposition of sediments either in the recent past or at the present time are apparent on the Hawaiian Arch, near the Line Islands, in the central Pacific from 160° to 175° E, between the 2,300 and 2,400 m isobath on the Solomon Rise and along the 4,000 m isobath in the Coral Sea.