ABSTRACT

A geochemical investigation of sediments and their interstitial waters was made on cores taken from the northern Gulf of Mexico slope in 1966. Cores from the top 1,000 feet of sediment were taken in water depths from 677 to 4,777 feet at 36 locations.

Measurements of water content and bulk density show that most of the slope sediments have been compacted under normal overburden pressure. Exceptions are those that were deposited either very slowly or very rapidly.

Away from salt domes, minor changes in the incorporated sea water in sediments have taken place with 1,000 feet of burial, suggesting mainly the loss of water through compaction, and the loss of dissolved sulfate through bacterial action. Near salt domes, interstitial waters have high salinities which are apparently derived from waters moving, in response to compaction near salt bodies and cap rock, past the salt and upward through the sediments over the dome, displacing the original interstitial water.

Interstitial waters of the sediments near salt domes have characteristics similar to those of some deep oil field brines. It is probable that some subsurface waters in deep sediments have developed high salinities by coming into contact with salt bodies and their associated cap rocks.