The history of the climate is recorded in deep sea sediments and reflection seismology is one of the principal methods of studying these sediments. Yet we have a poor understanding of the relation between observed seismic reflection records and variations in physical properties of deep sea sediments. In order to investigate the relationship between the observed sequence of seismic reflections in the deep ocean and various physical and chemical oceanographic events over the last 30 million years the principal investigators propose to collect high resolution seismic data on the Ontong Java Plateau where water depths range from 2000 meters to 4500 meters and where a series of existing and proposed drill holes provide a detailed record of oceanographic events over this time period. This region is one of the few regions of the world where seismic lines can be run continuously over this depth range without encountering major structural or erosional interruption. This depth range is critical because sediments deposited in depths of 4500 meters will have experienced considerable dissolution of carbonate, a major component of the sediment record; sediments as shallow as 2000 meters will not have experienced this dissolution. It is thought that the seismic reflection record in the deep Pacific Ocean is related to periods of varying degrees of dissolution. It is not known what causes the impedence contrasts that produce the reflection record in shallower waters away from sources of terrigenous sediment. Seismic lines tying directly from the deep ocean to intermediate depths will be important in advancing our understanding of observed seimic records.
